LAPAN-TUBSAT : FROM CONCEPT TO EARLY OPERATION

Transcription

1 LAPAN-TUBSAT : FROM CONCEPT TO EARLY OPERATION Editors : Soewarto Hardhienata Robertus Heru Triharjanto

2 Table of contents Table of contents... ii List of Tables... iv List of Figures... v Contributors... vii Foreword from Chairman of National Institute of Aeronautics and Space... viii 1 THE STRATEGY OF INDONESIAN SATELLITE TECHNOLOGY DEVELOPMENT INTRODUCTION Satellite System for Indonesian Geographical Condition Strategic Challenges of Indonesian Space Technology Trends of the International Satellite Technology Developments Stimulation of the National Capability Development NATIONAL CAPABILITIES, INTERNATIONAL COLLABORATION OPPORTUNITY, AND DEVELOPMENT STRATEGY National Capability Foreign Collaboration Opportunity Development Strategy DEVELOPMENT PHASES ENCLOSURE CHRONOLOGY OF LAPAN-TUBSAT DEVELOPMENT The cooperation leading to the program Program Implementation LAPAN-TUBSAT MISSION CONCEPT Missions and Constraints Mission Analysis LAPAN-TUBSAT SYSTEM BUDGET LAPAN-TUBSAT MASS PROPERTIES Mass Distribution Coordinate System Center of Gravity Measurement POWER BUDGET LINK BUDGET LAPAN-TUBSAT ATTITUDE DETERMINATION AND CONTROL SYSTEM ATTITUDE CONTROL STRATEGY ATTITUDE CONTROL HARDWARE Fiber Optic Gyro Solar Cells as Sun Sensor Star Tracker Reaction Wheel and Wheel Drive Electronics Air Coil LAPAN-TUBSAT POWER CONTROL AND DATA HANDLING PCDH HARDWARE PCDH SOFTWARE THE PAYLOAD OF LAPAN-TUBSAT MISSION...35 ii

3 7.2 HARDWARE & SOFTWARE mm focal length camera Focus Control System Software mm focal length camera LAPAN-TUBSAT COMMUNICATION SYSTEM 1: ON-BOARD HARDWARE TT & C TRANSCEIVER S-BAND TRANSMITTERS LAPAN-TUBSAT COMMUNICATION SYSTEM 2 : GROUND STATION GROUND STATION ADAPTER GROUND STATION PREPARATION & TEST MECHANICAL AND ELECTRICAL INTERFACE OF LAPAN-TUBSAT LAPAN-TUBSAT STRUCTURE Requirements Design Dynamic Characteristics Testing LAPAN-TUBSAT HARNESS LAPAN-TUBSAT LAUNCH CAMPAIGN LAUNCH PLAN LAUNCH CAMPAIGN EARLY OPERATIONS OF LAPAN-TUBSAT FIRST ACQIUSITION CONTROLLING THE ATTITUDE PAYLOAD DATA RECEIVING iii

4 List of Tables Table 3-1 Orbital parameter of PSLV-C7 launch...13 Table 4-1 Mass LAPAN-TUBSAT Components...14 Table 4-2 LAPAN-TUBSAT Mass Properties...17 Table 4-3 Power consumption for picture mode...18 Table 4-4 Power consumption for full hibernation mode...18 Table 4-5 Power consumption for hibernation mode...18 Table 4-6 Budget for one picture taking operation...19 Table 4-7 Power Production Capability...19 Table 4-8 Recharging Capability...19 Table 4-9 Link Analysis for LAPAN-TUBSAT & UHF Rumpin G/S...20 Table 4-10 Link Analysis for LAPAN-TUBSAT & S-band Rumpin G/S...22 Table 6-1 PCDH attitude control commands...33 Table 6-2 PCDH store-forward communication commands...33 Table 10-1 PSLV sine vibration test requirement...53 Table 10-2 PSLV random vibration test requirement...53 Table 10-3 Result Of Resonance Search Test...54 iv

5 List of Figures Figure 1-1 Milestone of Indonesian Satellite Technology Development... 4 Figure 1-2 Milestone of 2 nd generation satellite development program... 6 Figure 2-1 MoU signature between LAPAN TU Berlin and DLR Figure 2-2 Solar panel testing supervised by Prof. Renner at TU Berlin... 9 Figure 2-3 Test of High Resolution Video Camera and Satellite Engineering Model... 9 Figure 2-4 Component and integration & harnessing of LAPAN-TUBSAT at TU Berlin Figure 2-5 Match-Check of PSLV-C7 rocket adaptor on LAPAN-TUBSAT satellite by ISRO.. 11 Figure 2-6 Packing of LAPAN-TUBSAT satellite in its container before transporting to India.. 11 Figure days passes of LAPAN-TUBSAT and the coverage of Rumpin and Biak G/S Figure 4-1 LAPAN-TUBSAT Coordinate System Figure 4-2 C.G. Measurement of LAPAN-TUBSAT Figure 4-3 C.G. Compensation Figure 5-1 Configuration of Attitude Determination System Figure 5-2 Slew Capability of LAPAN-TUBSAT Figure 5-3 LAPAN-TUBSAT Target Pointing Figure 5-4 Attitude Control System Assembly Figure 5-5 Definition of Gyro Rotation Axis Figure 5-6 Reference Frame Definition Figure 5-7 CMOS Star Tracker Figure 5-8 Reaction Wheel and WDE Figure 5-9 Air Coil Assembly on LAPAN-TUBSAT Structure Figure 6-1 LAPAN-TUBSAT PCDH during component test Figure 6-2 Schematics of LAPAN-TUBSAT computer Figure mm lens, 3 chips camera, lens actuator Figure 7-2 Block Diagram of LAPAN-TUBSAT Focus Control System Figure mm lens, kappa camera, baffle and mounting system Figure 8-1 LAPAN-TUBSAT TTC unit Figure 8-2 LAPAN-TUBSAT UHF antenna Figure 8-3 S-band transmitter and antenna Figure 9-1 LAPAN-TUBSAT/MODIS ground station in Rumpin Figure 9-2 LAPAN-TUBSAT G/S flowchart Figure 9-3 LAPAN-TUBSAT visibility on 22 April :19:00 WIB Figure 9-4 Video frame from DLR-TUBSAT above Indonesia taken from Rumpin Figure 10-1 Upper compartment Figure 10-2 Lower compartment Figure 10-3 Battery mounting Figure 10-4 Exploded view of Sony camera platform Figure 10-5 Normal Mode for frequency Hz Figure 10-6 Normal Mode for frequency Hz Figure 10-7 Test setup for Y axis vibration Figure 10-8 LAPAN-TUBSAT Main harness including battery connectors Figure 10-9 LAPAN-TUBSAT harness installed on Lower Deck Figure 11-1 PLSV-C7 payload bay Figure 11-2 Fitting check with IBL Figure 11-3 LAPAN-TUBSAT separation scenario v

6 Figure 11-4 LAPAN-TUBSAT container being closed prior to shipping...58 Figure 11-5 Integration of LAPAN-TUBSAT to PSLV...59 Figure 11-6 PSLV C7 fairing closure...59 Figure 11-7 Launch of PSLV C Figure 12-1 Orbital Parameter of LAPAN-TUBSAT From ISRO after Separation...61 Figure 12-2 Orbital Elements of New Flying Object by NORAD...62 Figure 12-3 Orbital Elements of LAPAN-TUBSAT by NORAD...62 Figure 12-4 Power Control Unit Telemetry of LAPAN-TUBSAT...63 Figure 12-5 First OBDH Telemetry of LAPAN-TUBSAT...64 Figure 12-6 Power On Time Setting in the First Tracking...65 Figure 12-7 Gyro Measurements of LAPAN-TUBSAT...66 Figure 12-8 Calculation of Nutation Angle (θ) from Gyro Measurements...66 Figure 12-9 Flat Horizon Indicate the Angular Momentum Perpendicular to the Orbit...67 Figure Captured Horizons of Drifting Angular Momentum...67 Figure Saturated Blue Channel on High Resolution Camera...68 Figure High Resolution Camera Image after Adjustment...68 Figure Merapi Volcano, Central Java, May 24 th Figure Jakarta, July 12 th vi

7 Contributors Abdul Rahman is LAPAN s Aerospace Ground Segment Technology Division Head that acted as LAPAN-TUBSAT Project Administrative Manager. He received Master degree in Optoelectronics from Universitas Indonesia. Agus Nuryanto was LAPAN s deputy chairman of Aerospace Technology that acted as LAPAN-TUBSAT program director. He received Doctorate Engineering degree in Polymer Technology, chemical engineering from "Ecole d'application surdes Hautes Polymres (EAHP)", Louis Pasteur University, Strasbourg, French. Ayom Widipaminto started his career in LAPAN as an engineer at LAPAN s Remote Sensing Division. He received Bachelor degree in Electrical Engineering from Institut Teknologi Bandung. He was a member of LAPAN-TUBSAT s Assembly, Integration, and Test team and is currently the team leader for developing LAPAN-TUBSAT-based satellite computer. Eriko N. Nasser started his career in LAPAN in 2001 as an intern Aerospace Electronics Technology Center. He received Bachelor degree in Aerospace Engineering from Institut Teknologi Bandung. He is a member of LAPAN-TUBSAT s operation team and in-charge of the Rumpin ground station. Mahdi Kartasasmita was the chairman of LAPAN during the development of LAPAN- TUBSAT. He received his PhD in remote sensing from University of California Davis, USA, and initiated the application of satellite-based remote sensing system in Indonesia. He is currently the chairman of National Research Council. Mohammad Mukhayadi started his career in LAPAN in 2001 as an intern Aerospace Electronics Technology Center at LAPAN. He received Bachelor degree in Aerospace Engineering from Institut Teknologi Bandung. He was a member of LAPAN-TUBSAT s Assembly, Integration, and Test team and is currently the team leader for LAPAN-TUBSAT operation team. Mochamad Ichsan was an RF engineer for Aerospace Electronics Technology Center at LAPAN. He assisted in the development of LAPAN-TUBSAT TT&C ground station in Rumpin and Biak. He is currently the head of LAPAN-ISRO TT&C ground station in Biak, and currently assisting the development of LAPAN-TUBSAT 2 nd groundstation. Robertus Heru Triharjanto started his career in LAPAN in 1997 as design engineer at LAPAN s Center for Aerospace Vehicle Technology. He received Master degree in Aerospace Engineering from Texas A&M University. He was the Indonesian team leader for LAPAN- TUBSAT Assembly, Integration, and Test. Soewarto Hardhienata was the Director of Aerospace Electronics Technology Center at LAPAN that acted as the Head of LAPAN s microsatellite development team. He received his Doctorate degree in computer science from University of Erlangen-Nuernberg Germany. He is currently LAPAN s deputy chairman of Aerospace Technology. Toto Marnanto Kadri was the Head of LAPAN s Cooperation and Public Relation Bureau, in which he managed the cooperation with TU Berlin during the development of LAPAN- TUBSAT. He is currently the Director of Aerospace Electronics Technology Center of LAPAN. Wahyudi Hasbi started his career in LAPAN in as an engineer for LAPAN-ISRO TT&C Ground Station in Biak. He received Bachelor degree in Physics from Universitas Hasanudin. He was a member of LAPAN-TUBSAT s Assembly, Integration, and Test team and is currently incharge for developing hardware for LAPAN-TUBSAT 2 nd groundstation. vii

8 Foreword from Chairman of National Institute of Aeronautics and Space Indonesia is an extensive country, stretching about one-eigths of the equator, with more than 220 million inhabitants of diverse ethnics and cultures, while the Indonesian maritime continent also contain diverse environment, climate and natural resources. The Indonesian maritime continent is also believed to have an important role to the global environment. With the extensive and diverse geography of the country and need for a sustainable economic growth Indonesia have realized the importance on the utilization space for national development since the relatively early stages. Efforts on development of aerospace research started in the early 60 s particularly by the armed forces and universities. In 1964 Indonesia developed and launched Kartika-I sounding rockets and telemetry to gather data on tropical atmosphere, followed in 1965 by launch of Kappa-8 sounding rockets in cooperation with Japan in participation in the International Sun Quiet Year Acquisition of first satellite telemetry signal from United States TIROS satellite was conducted in Bandung in In 1976 Indonesia started operation of its first Palapa series of domestic communication satellite system, and is the third country in the world to utilize satellite communication system after the United States and Canada. With the need to organize space programs within the government the establishment of National Institute of Aeronautics and Space LAPAN is concluded on 27 November 1963 to implement research and development on space science, technology and application, as well as to formulate national policies in the utilization of space. In consideration to the importance on the utilization of space in Indonesia it is expected that LAPAN develop space technology and its application for the specific requirements of Indonesian national development. LAPAN developed and integrated ground segments for important foreign satellite missions, in particular remote sensing satellites. Space remote sensing data acquisition and processing began with NOAA APT data in Jakarta, Presently, LAPAN have generated the latest NOAA AVHRR, Landsat, SPOT, GMS, ERS-1/2, JERS-1 and MODIS satellite data products from ground stations in Parepare, Jakarta, Biak and Bogor. The application of satellite remote sensing data is extensively used for national development in monitoring and application to natural resources, environment, land use planning as well as disaster mitigation. Furthermore, the provision of space related services by Indonesian private companies have also expanded in many commercial applications, in particular telecommunication and information services as well as broadcasting, with operation of Palapa series, Telkom series, Garuda and Cakrawarta satellites. On the other hand, the costs and complexity on the development of space segment has been an obstacle that needs to be overcome in Indonesia. It is also important for LAPAN to develop space technology for self-sufficiency and sustainability of space applications according to the specific requirements of the Indonesian archipelago and peaceful purposes. The current technology advances in data processing and space communication components provided a possibility for development of cost-effective micro-satellites for remote sensing missions, however the technological obstacle remains. It is important for LAPAN to acquire cooperation with organizations in friendly developed countries to accelerate in the acquisition of advanced satellite technology to start a remote sensing satellite project. In this regard, LAPAN convey its gratitude to the Technische Universität Berlin (TU Berlin) in Berlin, Germany for the cooperation in the transfer of knowledge, skill and experience viii

9 on the design, manufacture, test, launch and operation of LAPAN-TUBSAT remote sensing micro-satellite. LAPAN would also like to give a special appreciation to Prof. Dr.-Ing. Udo Renner and his co-workers for the expertise and supervision to LAPAN engineers, and for the generous advice and consultations provided to LAPAN. LAPAN also convey its gratitude to Indian Space Research Organization for the professional and successful launch of LAPAN- TUBSAT satellite as auxilliary payload to Cartosat-2 and SRE missions on board PSLV C7 launch vehicle on 10 January LAPAN have also enjoyed significant cooperative activities with Deutsche Forschungs und Versuchsanstalt für Luft und Raumfahrt (DFVLR) of Germany in various aerospace applications since 1976, commencing with remote sensing, energy and telecommunications as in the Special Arrangement signed in This bilateral bilateral cooperation have provided LAPAN with a stronger basis for the development on space technology applications. The close relation between LAPAN and German Aerospace Center (DLR) in wider fields of cooperation is continued and strengthened until today. LAPAN-TUBSAT micro-satellite is currently performing excellently in its orbit, providing a wealth of information in video scenes and images of Indonesian land use, environment and natural resource acquired by ground station in Rumpin, Bogor. Although LAPAN-TUBSAT satellite is still in its early stages of in-orbit operation, as demonstration satellite a number of video image application is performed using existing remote sensing image correction and data evaluation methods for various potential applications in vulcanology, municipal and rural development, environment observations and others. The use of both high resolution color video image and wide swath color video image have indicated many advantages in the use of video cameras for earth observation. It is expected that LAPAN shall set-up more LAPAN-TUBSAT ground stations in Indonesia for satellite control and data acquisition in the near future. Similar LAPAN-TUBSAT satellite video scenes could also be acquired in Germany. With the accomplishment of LAPAN-TUBSAT micro-satellite in orbit, LAPAN is now ready and commited to take the responsibility on the design and manufacture of the next remote sensing micro-satellite to be carried out in Indonesia. The satellite mission requirements and technical design are being completed, and it is expected that the development and integration of the satellite could be commenced in 2008 and ready for launch by The design, manufacture, launch and operation of LAPAN-TUBSAT micro-satellite have provided Indonesia with another important milestone in its development of space technology and application for its present and future national development that is made possible with collaboration of friendly partners in Germany and India. Dr. Ir. Adi Sadewo Salatun ix

10 Foreword from LAPAN-TUBSAT Chief Engineer The Technical University of Berlin is engaged since 1985 in the development of small satellites (TUBSAT) for hands-on education of students but also of engineers from national space agencies like DLR in Germany or CRERS in Morocco. Other universities follow the same approach, some of them with significantly more resources like the University of Surrey in UK or the University of Stellenbosch in South Africa. In this context our University is very proud that we have been selected by LAPAN against international competition for a fixed price contract where a mixed team including 16 Indonesian players had to design, develop, manufacture and test a 50 kg satellite LAPAN-TUBSAT within two years. As promised, two years after the kick-off the satellite was handed over to LAPAN in an impressive ceremony in the presence of the LAPAN Chairman, the University President and the Indonesian Ambassador. The launch happened a little later than expected because not all passengers kept their schedule so strictly but was professionally performed by ISRO. And to our big relief everything works well. We have received and are still receiving live video scenes of selected parts of the earth in high resolution and good quality from the LAPAN Ground Station in Rumpin but also from S-band receive stations in Berlin, Neustrelitz, Kiel and Spitzbergen. They have attracted considerable public attention not only in Indonesia but also on our side. Congratulations to the LAPAN team! You have proven that you can design, manufacture, test, launch and operate a small satellite. You should be ready now to start a second generation under your own responsibility. We wish you good luck, and should you have any questions, please, don t hesitate to ask, we will be happy to assist you. Prof. Dr-Ing. Udo Renner x

11 Forewords from Editors The book is intended for Indonesian college students and professionals interested in LAPAN-TUBSAT project. LAPAN-TUBSAT, the first Indonesian micro-satellite, is finally launched and operates. The LAPAN-TU Berlin join project marks the beginning of the mastering of satellite engineering knowledge in Indonesia. The book on LAPAN TUBSAT is written in English in order to serve International audience as well as English speaking Indonesian academic communities. The book is organized in 12 chapters, starting with the discussion of on the strategy of Indonesian satellite technology development, which is done in several phases and begin with extensive international collaboration. The second chapter details the chronology of LAPAN- TUBSAT development, which is the implementation of the first phase in the satellite technology development strategy. The third chapter discusses the mission concept of LAPAN-TUBSAT, which also detailing its design constraints. The fourth chapter discusses the system budget of LAPAN-TUBSAT, in which is the consequences of its design constraints. Chapter five to chapter ten speak about various subsystem of LAPAN-TUBSAT. Chapter five discusses the attitude determination and control system of LAPAN-TUBSAT, which includes its control strategy and hardware. Chapter six details the hardware and software of LAPAN-TUBSAT s main computer which called Power Control and Data Handling system. Chapter seven explains the payload of LAPAN-TUBSAT, which as according of its mission are video cameras. Chapter eight and nine discusses the communication system of LAPAN-TUBSAT, in which the earlier discusses the system on-board of the satellite, while the later discusses the system on LAPAN-TUBSAT s ground station. Chapter ten details the mechanical and electrical interface of LAPAN-TUBSAT, which includes its structure and harness. Chapter eleven tells about LAPAN-TUBSAT s launch campaign as auxiliary payload for the Indian s PSLV-C7. Last but not least, chapter twelve describes the early operation of LAPAN-TUBSAT, which includes images taken during the first six months of operation We, the editors, certainly hope that the success of LAPAN-TUBSAT mission would ensure the continuation of Indonesian satellite program. It is expected that the book could stimulate collaboration of national potency and support from the various interested individuals and institutions for the success of the program. Rumpin, September 2007 Editors xi

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13 1 THE STRATEGY OF INDONESIAN SATELLITE TECHNOLOGY DEVELOPMENT S. Hardhienata, M. Kartasasmita 1.1 INTRODUCTION Satellite System for Indonesian Geographical Condition Indonesia consists of more than 17,000 islands, ranging from small to big in size. The islands are distributed between Sabang in the west of Indonesia and Merauke in the east. This condition forces Indonesia to use satellite to explore the space for communication applications and other utilizations. The main obstacle for Indonesia in preparing the space utilization for its national development sustainability and national improvement is its dependency on the satellite industries of the developed countries, such as the United States and European Countries. These obstacles are more apparent if the Indonesian geographical range and structure is considered into the satellite-based space utilization system. Because of the wide range and structure of the Indonesian archipelago, it strives for a modern space utilization system which is currently for Indonesia still insufficient. One of the solution which is considered appropriate is by developing a satellite system for Indonesian space utilization, such as for digital data communication, climate data collection, remote sensing, and navigation Strategic Challenges of Indonesian Space Technology Even though Indonesia has experience in operating/using space technology for more than 25 years, Indonesia is left behind several Asian countries such as Japan, India, China, and South Korea in mastering space technology. In order to catch up with this fact of having fallen behind, Indonesia is trying to speedup the activities in mastering space technology through conducting a concrete space development program. To face this strategic challenge, LAPAN as an institution who is responsible in conducting research activities, development, and application of the aerospace system, is currently coordinating the Indonesian satellite development program by gathering the existing national capabilities and international potentials Trends of the International Satellite Technology Developments The small satellite applications, which are mainly positioned in low orbit, such as for communication in isolated areas, earth observation, environmental and meteorological observation has increased moreover these days. This tendency is apparent by the rise of several Asia Pacific countries in producing and developing small satellite system, such as South Korea, Pakistan, Singapore, Malaysia, Thailand, etc. These increasing trends can easily be understood because the production and development of the micro/small satellite is easier and cheaper if compared to the development of big satellites. The low cost occur due to the small production period and launching cost. The small satellite could provide services such us for: 1

14 store and forward data communication services for transportation and environmental management application; remote sensing for natural resource, agriculture and forestry management application; as an instrument for certain space science scientific experiments; as a demo instrument for technological performance in the orbit (small scale). Based on the descriptions mentioned above, it is clear that Indonesia should anticipate the rising trends by joining the trends, namely by conducting national space system research and development Stimulation of the National Capability Development Besides as a space technology development tools, especially in electronics and informatics, the satellite development program can also be applied to stimulate the national capability development and can be used as a promoter to produce commercial products with hitech, modern, and competitive technology. The stimulation implementation effort can be manifested by conducting exploration in three activity areas, which consists of: Technological Development, by promoting the applied electronic technology in space sector and its development to produce hi-tech based products, as is being conducted by several neighboring countries. National Technology Alliance, to develop the national strategic industrial ability which is needed for the national development. Product Fabrication Training, to provide training for the community in the industrial, research institution, and high education sectors, so that they are able to produce hi-tech and modern technology in a short period. All of the exploration fields stated above are expected to spur the interest to improve the institution development, skills, and technology and could be used to establish a national industry which based on hi-tech and modern technology as well as able to produce specific products which are globally competitive. 1.2 NATIONAL CAPABILITIES, INTERNATIONAL COLLABORATION OPPORTUNITY, AND DEVELOPMENT STRATEGY National Capability From the national point of view, there are already several institutions in Indonesia who have development facilities and/or human resources which dealing with satellite sectors. As an example, there exists a Micro Satellite Team in LAPAN who has already developed a satellite system since 1999/2000 and is currently successful in constructing a micro satellite, named LAPAN-TUBSAT. Besides, LAPAN owns several supporting facilities in the form of laboratories and several satellite receiving ground stations. The other institution is the Bandung Institute of Technology, who has several human resources, clean room facility for small satellite integration, and a micro satellite ground station receiver. Meanwhile, the industries in Indonesia who are able to support this program are PT. LEN, PT. INTI, and PT. Dirgantara Indonesia Foreign Collaboration Opportunity 2

15 The development of national satellite system requires a collaboration with institutions or countries that has experience and capability in developing satellite technology. Through this collaboration, a technology transfer from the institutions and countries to Indonesia would be expected. Several institutions that provide collaboration are: Surrey Space Center-UK, DLR- Germany, TU-Berlin, ISRO-India, SATREC Initiative of South Korea, and Sunspace of South Africa. The applied consideration in choosing the most appropriate collaboration comprises the financial, experience, and capability matters of these institution/countries in satellite technology and their hand-on experience as well as the skills offered to the human resource in Indonesia. Besides, it is also considered whether the offered collaboration program is appropriate with the facility and skills owned by Indonesia, so that the development should not be started from zero Development Strategy From several considerations stated above, it is concluded that the most appropriate alternative to start the development of satellite technology in Indonesia is by collaborating with TU-Berlin for satellite manufacturing and with ISRO India for satellite launching. In order to reach the goal and to concretize the satellite technology development and mastery program, the Research and Technology State Minister of Republic of Indonesia has appointed LAPAN to become the lead agency with establishing a National Micro Satellite Team. This team involves several relating institution in Indonesia, both governmental and private institutions. The objective of the establishment of the team is to gather/optimize the available national ability, so that in the future this satellite technology mastery will be a result of national collaboration and will provide wide benefit for the national development as well as spurring the national private role in the satellite industry development in Indonesia. 1.3 DEVELOPMENT PHASES Indonesia began to develop satellite technology trough the National Institute of Aeronautics and Space (LAPAN). LAPAN is a governmental institution for research and development on space science & technology and its application in Indonesia. Generally, Indonesia satellite technology development program can be divided in four phases, namely preparation phase, technology proficiency phase, technology proficiency based application and experimental based application phase, whereas the activities can be divided into two segments, the space segment and the ground segment as shown in Figure

16 Phase 0 Figure 1-1 Milestone of Indonesian Satellite Technology Development Phase 0 is the preparation phase and was conducted from 2000 until The preparation consists of several activities in space and ground segments. The activities in the space segments included the study of satellite international and its development possibilities in Indonesia as well as development of an engineering satellite models. The activities in the ground segments comprised the development of an amateur satellite ground station for Low Equatorial Orbit (LEO) in Rancabungur, West Java Indonesia and the installation as well as operation of TTC ground station in Biak, Papua. During the preparation phase, LAPAN has conducted several workshops, namely LAPAN German Aerospace Center (DLR) Joint Workshop in Small Satellite Development and its Application, LAPAN - Indian Space Research Organization (ISRO) Joint Workshop on Level Aspect of Satellite Technology, and LAPAN Malaysian Astronautics Technology Sdn. Bhd. (ATSB) Joint Workshop in Small Satellite Development. Phase I Phase I is the technology proficiency phase which is the continuation of the first phase and was conducted from 2003 until now (2005). As before, the technology proficiency phase consists of several activities in the space and ground segments. The activities in the space segments include the development of the Indonesia Nano Satellite INASAT-1, the LAPAN- TUBSAT satellite and the preparation of the 2 nd generation satellite. Whereas the activities in the ground segment consists of the SCC ground station preparation and training as well as the installation of LAPAN-TUBSAT ground station. The INASAT-1 is an in-house program and a cooperation project between LAPAN and related institutions in Indonesia, such as PT Dirgantara Indonesia, PT LEN, Institute Technology of Bandung (ITB) and the Indonesia Science Institute (LIPI). The mission of INASAT-1 program consists of flight demonstration, probe/measure of environmental condition, analysis and 4

17 verification of flight model and characterization of environmental and spacecraft temperature as well as characterization of the earth magnetic field. The program objective of INASAT-1 is to obtain a simple hands-on experience in designing and integrating satellite. The LAPAN-TUBSAT is a video surveillance micro satellite that was developed at the Technical University of Berlin Germany, by a team of Indonesian engineers. The satellite is planned to be launched as piggy in early 2007 by a Polar Satellite Launch Vehicle launcher from Sriharikota India, carrying a S-band data transmission system, a high-resolution video camera, a low-resolution video camera, and a short text store and forward messaging. The objectives of LAPAN-TUBSAT development program is to provide the Indonesian engineers with the skill to design, construct, test, and operate LAPAN-TUBSAT class Micro- Satellite as well as to provide Indonesian engineers with the knowledge on the micro satellite off-the-self components. LAPAN will operate two ground stations to control the LAPAN-TUBSAT satellite, namely the Rumpin ground station located in Jakarta and the Biak ground station in Papua, East of Indonesia. The ground station location is chosen in such a way so that the coverage area is large enough to cover the nation archipelago. Figure 3 shows the coverage of the LAPAN- TUBSAT from both ground stations. LAPAN-TUBSAT ground station consists of two systems: one is the S-band system to receive video image from the camera payload, and the other is the TTC system to send command and receive telemetry from the satellite. The scheme of the TTC and S-Band ground station system is illustrated in figure 4. The TTC station consists of steer-able UHF antenna, transceiver and ground station computer. The computer run two programs, one is to determine the pointing direction of the antenna and the other to generate command protocol and interpret the satellite telemetry. The S-band station consists of steer-able S-band antenna, antenna control computer, FM analog video receiver and PAL video recorder/display. An additional computer to convert analog video into digital image frame can be attached to the video recorder. The ground station has 4.5 m S-band disc. Phase II Phase II is the Technology Proficiency based Application Phase and will be conducted from 2006 to 2008/2009. Here the development of the 2 nd generation satellite will be continued from the preparation step in 2005 into procurement of the components and assembling as well as testing the satellite. The 2 nd generation satellite is planned to be launched in the end of 2008 or Since 1999, the Indonesian National Institute of Aeronautics and Space (LAPAN) and Indian Space Research Organization (ISRO) have established Tracking, Telemetry and Command (TTC) station in Biak Island (Biak-I). Biak-I serve as one of the important Down Range Stations (DRSN) for Geo-synchronous Satellite Launch Vehicle mission. Biak-I is also used for monitoring 3rd stage performance, spacecraft (GSAT) injection into orbit and preliminary orbit determination. Besides, Biak-I provides round the clock TTC support for IRS- 1C, IRS 1D, IRS-P3, IRS P4 and TES missions. Installation of the second TTC station Biak-II (S and C-band, CCSDS standard) is currently completed. Biak-II is one of the prime C-Band TTC Stations for GSAT in LEOP phase. Biak-II serves as an alternative to Perth INTELSAT C-Band TTC Station and can be used to 5

18 monitor spacecraft snap signal and propellant venting operations. Biak-II is able to provide back up support to Biak I in Transfer Orbit Phase and will also enhance the visibility coverage requirements for the remote sensing satellite missions of ISRO. With these two stations in Biak, LAPAN and ISRO are ready to support any external agencies that require TTC support from this location. Phase III Figure 1-2 Milestone of 2 nd generation satellite development program The phase III is the experimental based application phase that will be conducted from The phase III consists of operational, application and development activities of the 2 nd generation satellite. During that phase, assembling, tests, and launch activities of the 3 rd generation satellite will be done as well as the commercialization of TTC Biak Ground Station. 1.4 ENCLOSURE Indonesia has already established a National Satellite Team in order to master satellite technology and to decrease its dependency upon other countries. The National Satellite Team is currently conducting the micro satellite development program collaborating with TU-Berlin. This program is implemented by gathering national abilities both from the government and private sectors in Indonesia. The obtained results are the completion of the LAPAN-TUBSAT satellite construction which will be launched in September Meanwhile, Indonesia is currently developing its second generation satellite whose mission is to apply remote sensing technology to support the national food sustainability program. The development of the second generation satellite is expected to be complete in 2008 and planned to be launched in the end of 2008 or With a good planning and a right strategy, as well as consistent commitment from the related parties, it is expected that the Indonesian satellite development program will reach its objective, namely the national capability and independency in satellite technology. 6

19 2 CHRONOLOGY OF LAPAN-TUBSAT DEVELOPMENT A. Nuryanto, T. M. Kadri, A. Rahman 2.1 The cooperation leading to the program Indonesia has been developing satellite technology during the last few years through the National Institute of Aerospace and Space (LAPAN) which has been appointed as the executing agency according to its task and function. The activity was commenced by conducting international satellite assessment and the possibility to be developed in Indonesia as well as by undertaking satellite Engineering Model development from 2000 to During this period, LAPAN together with its foreign partners also organized several workshops, namely: LAPAN German Aerospace Center (DLR) Joint Workshop in Small Satellite Development and its Applications, held in Jakarta. LAPAN Indian Space Research Organization (ISRO) Joint Workshop on Level Aspect of Satellite Technology in Bogor. LAPAN Malaysian Astronautics Technology Sdn. Bhd. (ATSB) Joint Workshop in Small Satellite Development in Bogor. The outputs of these workshops were of great importance, because it produced several opportunities to perform collaboration on satellite technology development which might be followed by a satellite construction. Figure 2-1 MoU signature between LAPAN TU Berlin and DLR. Throughout the mentioned assessments above, it was concluded that there are three satellite development strategies for implementation in Indonesia, namely: making efficient use of national capacity, collaborating with foreign partners, design-to-cost strategy development. One the option in the execution of this program was by performing collaboration with Germany because Indonesia (LAPAN) and Germany (DLR) have a long history in scientific collaboration research. Collaboration was established between LAPAN and the Technische Universitaet Berlin (TU-Berlin) considering the university s experience in developing micro satellites such as TUB-Sat, MAROC-SAT etc. Two Memorandum of Understanding (MoU) 7

20 were signed on July 21, 2003, namely between LAPAN and DLR Germany, and between LAPAN and TU-Berlin. The MoU opened the way for the development of the LAPAN-TUBSAT micro satellite. The satellite is a video surveillance satellite, carrying a S-band transmission data system, one high resolution color video camera (up to 5 m resolution), with swath width of 3,5 km, and one low resolution camera video 200 m with swath width 81 km. It is also equipped by telemetry and telecommand transmission for store and forward communication, using UHF frequency with 1200 bps of baud rate. As a surveillance satellite, LAPAN-TUBSAT can be directly utilized for earth monitoring such as to monitor forest fire, volcanoes, flooding etc. The store and forward data communication might be used for remote area communication and mobile communication. The satellite has an attitude maneuver capability trough interactive commandment from the ground, so that monitoring in certain location can be controlled while it passes above Indonesia. The satellite maneuver attitude utilities an attitude control system that comprises 3 reaction wheels, 3 gyros, 2 sun sensors, 3 magnetic coils and 1 star sensor for satellite navigation. The required power is provided by 5 batteries with 12 Ah capacity and 4 solar panels. 2.2 Program Implementation The development of LAPAN-TUBSAT provides experience for Indonesian engineers especially in satellite designing, testing, integrating, operating and procuring satellite component in the market (off the self component). The Indonesian engineer team is composed of 4 LAPAN s engineers who actively participate in the satellite development at TU-Berlin under the supervision of Professor Udo Renner of TU-Berlin for a period of 18 months, covering the designing, testing, integrating and operating of the satellite. In addition, there were 10 engineers from several institutions namely LAPAN, ITB, LIPI, PT.DI, and PT.LEN who have also been involved in the satellite development. They stayed in TU-Berlin for a replacement period of every 3 months, according to the development step of the micro satellite. The engineers have been directly involved in the satellite s development process as well as in the manufacturing, commencing from the design, component level testing, integrating, satellite level testing, launching preparation and the establishment of ground station in Indonesia. They also obtain satellite technology lectures, so that their experience will be very useful for the development of the next satellite. The LAPAN-TUBSAT development was undertaken in three stages, namely: Testing and integration of sub-system component, Structure manufacturing, Satellite level testing. All the development process were commenced in 2003, and completed in July 2005 according to the schedule. The satellite is ready for launch by using the Indian PSLV launcher. 8

21 Figure 2-2 Solar panel testing supervised by Prof. Renner at TU Berlin Figure 2-3 Test of High Resolution Video Camera and Satellite Engineering Model 9

22 Figure 2-4 Component and integration & harnessing of LAPAN-TUBSAT at TU Berlin LAPAN-TUBSAT will be launched by using the PSLV-C7 launcher, owned by the Indian Space Research Organization ISRO and based on the existing collaboration. The collaboration was performed considering the previous experience between the two parties during the establishment and operation of TT&C ground station in Biak, Papua, Indonesia. In connection with the launch plan, several Interface Control Document meetings between LAPAN as the satellite owner and India as the launching provider should be performed as a preparation of the satellite launching. According to its first planning, LAPAN-TUBSAT would be launched in October 2005, as a secondary payload, by means of Piggy Back, together with the Cartosat-2 Satellite and the Indian SRE Module Re-entry. However, due to some technical problems, the launch will be delayed until January The micro satellite LAPAN-TUBSAT was manufactured in the TU-Berlin Germany, and was completed in July In April 2006, the satellite has been transported to India. From April - September 2006 LAPAN-TUBSAT was stored in ISAC/ISRO clean-room Bangalore, India. The satellite was transported to Shriharikota launching site in October During the storing, the satellite battery is regularly maintained by LAPAN engineers via remote monitoring developed by LAPAN and TU-Berlin. 10

23 Figure 2-5 Match-Check of PSLV-C7 rocket adaptor on LAPAN-TUBSAT satellite by ISRO Figure 2-6 Packing of LAPAN-TUBSAT satellite in its container before transporting to India. 11

24 3 LAPAN-TUBSAT MISSION CONCEPT R.H. Triharjanto, M. Mukhayadi 3.1 Missions and Constraints The highest level constraints in LAPAN-TUBSAT development are : 1) Piggyback compatibility; As the satellite is LAPAN s 1 st experimental satellite. The launch opportunity for satellite is defined to be a piggyback payload. This determines the maximum dimension and weight of the satellite; the constraint then derives very strict power budget for the satellite. 2) Financial support; LAPAN provide the cost of the satellite, i.e. for the procurement of the satellites components and for the expertise of TU-Berlin human/engineering resources in design and manufacture of the satellite. The constraint derives that most of the components should be off-the-self since the budget and development time are very limited. The mission of the LAPAN-TUBSAT are : 1) Attitude determination and control test platform; the mission was defined by TU-Berlin for the flight proofing of the attitude determination and control system such as the IRE reaction wheel 303, in which the wheel are slightly bigger than the previously used in DLR-TUBSAT and MAROC-TUBSAT, Vectronic CMOS star sensor, which is a new development star sensor. The new star sensor uses the experience of the star sensor development from MAROC-TUBSAT, which used CCD technology. The new star sensor will have bigger aperture and therefore bigger baffle. 2) Video surveillance; the agility of the micro satellite made it possible for surveillance of object in which the location is not pre-defined. Based on their experience with DLR- TUBSAT, in which an interactive video surveillance has been proven, LAPAN- TUBSAT design chose to fly CCD color video camera as main payload. 3) Short message store and forward The traditional remote sensing approach, which uses nadir pointing with linear CCD and sun synchronous (polar) orbit, takes about days to repeat the same image in the equatorial region. Meanwhile, some event that could be monitoring from satellite, such as forest fire, flood, landslide, earthquake, volcano eruption, ship or aircraft accident could not wait for such long delay. The repeat is even worse in microsatellite, since the swath is very narrow due to constraint in the use of swivel mirror (as in the scanning-type payload). Therefore, LAPAN-TUBSAT chose to have a unique mission strategy, in which its attitude can be manipulated off-nadir. 3.2 Mission Analysis LAPAN-TUBSAT is expected to be launched by PSLV, in which the main payload is Indian cartographic satellite, Cartosat-2, and therefore, the expected mission geometry is as follows : 12

25 Table 3-1 Orbital parameter of PSLV-C7 launch Altitude, H (km) 630 Inclination, I (deg) 97.9 Period (min) Longitude shift per orbit (deg) Ground track velocity (km/s) Angular velocity (deg/s) Circular velocity (km/s) Number of revolution per day The first Indonesian ground station is located in Rumpin, Bogor ( S; E), which would cover the western part of Indonesia. Another ground station is planed to be built so that the whole country s territory could be covered. Figure days passes of LAPAN-TUBSAT and the coverage of Rumpin and Biak G/S 13

26 4 LAPAN-TUBSAT SYSTEM BUDGET R.H. Triharjanto, M. Mukhayadi, W. Hasbi The main system budget for LAPAN-TUBSAT is mass properties, power, and communication link. The first one is to serve the dynamic characteristics of the satellite that was design for momentum bias attitude stabilization. The second one is to calculate the recovery time after picture taking operation. The third is to ensure that the quality of communication channel between the satellite and the ground station is sufficient. 4.1 LAPAN-TUBSAT MASS PROPERTIES Mass Distribution The mass properties of LAPAN-TUBSAT depend on the mass of the satellite s components. The mass of each component is listed below. Table 4-1 Mass LAPAN-TUBSAT Components Component Mass (gr) Mass (gr) POWER SUBSYSTEM 6880 Battery Unit 5200 Solar Panel Z, +X, -X, -Y 4 x 420 ACS 8236 Gyro X, Y, Z 3 x 140 Wheel X, Y, Z 3 x 1368 WDE X, Y, Z 3 x 264 WDE Holder 200 Coil X 440 Coil Y 360 Coil Z 460 CMOS Star Sensor 1020 Base of Star Sensor 440 PAYLOAD 8240 Kappa Camera 440 Sony Camera+electronics+damper 7800 PCDH & COMM SUBSYSTEM 2637 PCDH 1055 S Band Transmitter 292 S Band Antenna 160 UHF Antennas+conectors at X and -Y 2 x 180 TTC 1 & 2 2 x 385 STRUCTURE Middle Plate 4800 Z plus 2600 Z minus 3050 X plus 3150 X minus 3150 Y plus 5400 Y minus 5650 Harness and connectors 907 TOTAL

27 4.1.2 Coordinate System The coordinate system is defined as in Figure 4-1. This coordinate system is used as reference for placing of the components and mass properties calculation. 15 Figure 4-1 LAPAN-TUBSAT Coordinate System Center of Gravity Measurement The measurement of the center of gravity (C.G.) of LAPAN-TUBSAT uses the edge balancing method. The method is chosen due to the geometry of the satellite at which the C.G. needs to be measured (X-Z axis), which is a rectangle of 450 x 450 mm. The tolerance of C.G. measurement as requested by ISRO is 5 mm. The method based on the principle that if the C.G. is aligned (line perpendicular to the horizontal base) with one of the corner of the rectangle, the moment at that corner would be zero. Meaning that the object would be balanced (having to tendency to fall to the right or left). A thin rubber mat is put underneath the satellite to prevent the corner from sliding on the table. A camera tripod, which has capability also to tilt (has a ball joint) and has a worm gear elevator, is used to jack up one of the satellite side the slowly until the satellite is balanced on one edge. The balancing process started with the satellite laid its weight on the tripod. The heavy side is then slowly elevated. The elevation is stopped just as the satellite heavy side is move to another side (a finger is placed on the satellite top to justify the movement). As the satellite is approximately balanced, the pin-ruler is used to draw the line from the base edge to the C.G. (see Figure 4-2). The measurement is repeated using another edge of the satellite and the intersection of the lines is the location of the C.G.

28 Figure 4-2 C.G. Measurement of LAPAN-TUBSAT When the satellite C.G. is measured, all the satellite components have been installed except the solar panel, to avoid the risk of damaging the panels. Since the panels would be mounted on both sides of X-axis (X-plus and X-minus), the panels contribution to the C.G. would be self eliminating. On Z axis, however, which only Z-minus is to be installed with a panel, therefore, a compensation calculation needs to be performed as illustrated in Figure 4-3. The measurement result on the C.G. is at 217 mm from Z minus and 219 mm from X minus. The measurement of the satellite weight minus its solar panel is kg. Therefore, the compensation due to the missing of solar panel (weight 420 gr; thickness 2 mm) at Z minus 1.7 mm Since the measurement accuracy is in the order of mm, the number to be used to compensate the C.G. is 2 mm. Therefore the LAPAN-TUBSAT C.G. is at 215 mm from Z minus 219 mm from X minus. The C.G. value is to be used in to determine the mounting points on the satellite-pslv interface system. 16

29 Figure 4-3 C.G. Compensation Based on the information above and the location of each component, the mass properties are then calculated as. The highest cross product of inertia, which only 5% of the lowest major inertia would ensure minimal nutation of the satellite during its momentum bias mode. Table 4-2 LAPAN-TUBSAT Mass Properties Properties Direction Value Unit Total Mass 54, 7 kg C.G. X: 219 mm Measured Z: 215 mm X: 215 mm C.G. Y: 129 mm Estimated Using Solid Edge Z: 218 mm MOMENT OF INERTIA Estimated Using Solid Edge PRINCIPAL AXES Estimated Using Solid Edge PRINCIPAL AXES ORIENTATION Estimated Using Solid Edge Ixx 1,386 kg.m 2 Iyy 2,062 kg.m 2 Izz 1,441 kg.m 2 Ixy 0,035 kg.m 2 Ixz 0,063 kg.m 2 Iyz -0,003 kg.m 2 I1 2,064 kg.m 2 I2 1,481 kg.m 2 I3 1,344 kg.m 2 X -0,05 1,00 0,01 Y -0,54-0,04 0,84 Z 0,84 0,04 0,54 17

30 4.2 POWER BUDGET The power consumption for pictures taking operation, which duration of operation is 15 minutes, is as follows. Table 4-3 Power consumption for picture mode Device No Voltage[V] Current[mA] Duty-Cycle[%] Mean Power[W] PCDH ,84 TTC , ,60 Wheels electronics ,12 Wheels ,56 Gyro ,82 Star Sensor ,50 Coil ,50 S-Band ,16 Kappa Camera ,20 Sony Camera ,34 Stepper Motor , ,05 Total 47,09 Table 4-4 Power consumption for full hibernation mode Device No Voltage[V] Current[mA] Duty-Cycle[%] Mean Power[W] PCDH ,84 TTC ,68 Total 180 2,52 Table 4-4 and Table 4-5 show that the power consumption for standby mode without attitude control (full hibernation) is only 2,52 W, and standby mode with momentum bias attitude control (hibernation) is 4,76 W. Therefore, for one picture taking operation, the depth of discharge is only 8,5% of battery capacity as detailed in Table 4-5 Power consumption for hibernation mode Device No Voltage [V] Current[mA] Duty-Cicle[%] Mean Power[W] PCDH ,84 TTC ,68 Wheel+WDE ,24 Total 280 4,76 18

31 Table 4-6. Since, LAPAN-TUBSAT power production capability is 900 ma, as detailed in Table 4-7, the power required for 1 picture taking operation can be recovered in 2,3 hour in hibernation mode (see Table 4-8). Table 4-5 Power consumption for hibernation mode Device No Voltage [V] Current[mA] Duty-Cicle[%] Mean Power[W] PCDH ,84 TTC ,68 Wheel+WDE ,24 Total 280 4,76 19

32 Table 4-6 Budget for one picture taking operation Budget Unit Batt. Nominal Voltage (5x 2.75 V) 13,75 V Batt. Rated Capacity 10 Ah Mean Power for Operation 47,09 W Time of Operation 900 S Energy for Operation Ws Max. Batt.Energy Ws Dept of Discharge for Operation 8,5 % Table 4-7 Power Production Capability Unit Power Output: Si with 13,7% efficiencies (BOL) P BOL = 13,7% x 1367 W/m 2 187,28 W/m2 Power Production Capability at EOL(5yr) P EOL = P BOL L d 155,32 W/m2 Input Power of Solar Array 34x (42mm x 58 mm) P SA = A SA P EOL 13,55 W Input Current of Solar Array, Power max at 15,4 V I SA = P SA /V PMAX 900,45 ma Note: L d - Lifetime degradation, for Si in 5 year = 0,826 Table 4-8 Recharging Capability Stby Mbias Unit Worst Case EOL Average Input Current, 900,45 900,45 ma Continuous Current 180,00 280,00 ma Average Battery Charge Current 410,00 114,00 ma Average Battery Charge Power (13.5 Volt) 5,5 1,5 W Battery Charge Efficiency 90% 90% Battery Recharging Time after 1 Operation 1,3 2,3 Hours

33 4.4 LINK BUDGET Link budget is calculated to know theoretically the RF link quality between the satellite and ground station. LAPAN has prepared ground station for TTC function and video reception from LAPAN-TUBSAT located in Rumpin ( S; E). This link calculation calculated the RF link assuming LAPAN-TUBSAT orbit is 630 km SSO and the ground station is in Rumpin. These calculations consist of UHF Up & Downlink calculation also Video downlink calculation in S-band frequency. For UHF Uplink calculation with assumption that EIRP from ground station about 23,98 dbw then the margin to the satellite would be about 15,6 db. Downlink calculation for UHF with EIRP satellite about 3,94 dbw, and G/T G/S about -10 db/k then the margin at the G/S would be 17,55 db. Both of calculations used maximum range between satellite and G/S and others loss parameters. Concerning the S-band video downlink calculation from LAPAN-TUBSAT satellite to G/S Rumpin, calculation is carried out using 5 0, 10 0, 20, 45 0, 90 0 elevation, EIRP of satellite about 13,06 dbw and G/T of G/S about 15,32 db/k, others parameters of the G/S and losses parameters assumption. The calculation result that available margin for the video receiver is between 4,4 to 16,87 db for 5 to 90 0 elevations. Above calculation results theoretically mentioned that the link for all communication systems from LAPAN-TUBSAT satellite to G/S or vice versa for operation is in enough margins. However observation of the RF link during operation of the satellite should be carried out to compare with these calculations. It is to be noted that many interference or disturbance sources in real condition which could cause the RF link may not good. Table 4-9 Link Analysis for LAPAN-TUBSAT & UHF Rumpin G/S UHF UPLINK Transmitter RF output 25 Watt (db) 13,98 Antenna Gain (db)* 11 Cable Loss 1 Effective Isotropic Radius Power (EIRP) (dbw) : 23,98 Maximum range to Satellite (Km) 2900 Frequency (MHz) 437,325 Free Space Loss (Path Loss) (db): -154,50 Atmospheric Loss (db)* 0,7 G/T of Sat Receiver (db/k)* -32 Boltzman Constant (db) -228,59 Bandwidth (7,6 KHz) (dbhz) 38,81 C/No (dbhz) 65,38 C/N (db) 26,57 Data Bit rate (bps) 1200 Receive Eb/No (db) 34,59 Required Eb/No (Db) 15 Implementation loss (db)* 4 Available Link Margin (db) 15,59 21

34 UHF DOWNLINK Transmitter RF output 3,5 Watt (db) 5,44 Antenna Gain (db)* -1 Cable Loss 0,5 Effective Isotropic Radius Power (EIRP) (dbw) : 3,94 Maximum range to Satellite (Km) 2900 Frequency (MHz) 436,075 Free Space Loss (Path Loss) (db): -154,50 Atmospheric Loss (db)* 0,7 G/T of G/S Receiver (db/k)* -10 Boltzman Constant (db) -228,59 Bandwidth (7,6 KHz) (dbhz) 38,81 C/No (dbhz) 67,34 C/N (db) 28,53 Data Bit rate (bps) 1200 Receive Eb/No (db) 36,55 Required Eb/No (db) 15 Implementation loss (db)* 4 Available Link Margin (db) 17,55 *) Assumption 22

35 Table 4-10 Link Analysis for LAPAN-TUBSAT & S-band Rumpin G/S Downlink Video Video Video Video Video Modulation FM FM FM FM FM Polarization RHCP RHCP RHCP RHCP RHCP Downlink Frequency (MHz) 2220,0 2220,0 2220,0 2220,0 2220,0 Satellite Altitude (km)* Data Bandwidth (MHz) EIRP (dbw) 13,06 13,06 13,06 13,06 13,06 Satellite AR (db)* 1,5 1,5 1,5 1,5 1,5 Elevation Angle Nadir angle (deg,) 65,05 63,67 58,78 40,06 0,00 Elevation Angle (km) 2400, , ,64 854,09 630,00 Free Space Loss (db) 167,10 165,51 162,72 158,12 155,48 Atmospheric Loss (db) 0,37 0,03 0,03 0,03 0,03 Receive Isotropic Power (dbm) -124,40-122,48-119,69-115,09-112,44 Antenna Diameter (meters) 4,50 4,50 4,50 4,50 4,50 Antenna Efficiency (%) 48,49% 48,49% 48,49% 48,49% 48,49% Antenna Gain (db) 37,37 37,37 37,37 37,37 37,37 Ohmic Losses (db) 1,00 1,00 1,00 1,00 1,00 Feed Temperature (C) 23,00 23,00 23,00 23,00 23,00 Net Antenna Gain (db) 36,36 36,36 36,36 36,36 36,36 Sky Temperature (K) 38,4 27,4 21,7 18,7 17,9 Antenna Noise Temperature (K) 97,29 89,09 84,84 82,60 82,00 Receive System Temperature (K) 42,79 42,79 42,79 42,79 42,79 System Noise Temperature (K) 140,08 131,88 127,63 125,39 124,79 Calculated System G/T (db/k) 14,90 15,16 15,31 15,38 15,40 Antenna AR (db max,) 1,50 1,50 1,50 1,50 1,50 Polarization Loss (db max,) 0,13 0,13 0,13 0,13 0,13 Pointing Loss (db) 0,25 0,25 0,25 0,25 0,25 Receive Signal (dbm@lna input) -88,42-86,49-83,70-79,10-76,46 Ktb (dbm) -102,82-103,08-103,23-103,30-103,32 S/N (db) 14,40 16,59 19,52 24,20 26,87 Minimum required S/N (db) by RCVR 10,00 10,00 10,00 10,00 10,00 Clear Sky Margin calculated G/T 4,40 6,59 9,52 14,20 16,87 Elevation angle (deg,) 5,0 10,0 20,0 45,0 90,0 Receive Signal (dbm@lna input) -88,4-86,5-83,7-79,1-76,4 LNA Gain (db) 37,5 37,5 37,5 37,5 37,5 LNA out to RJ Loss (db) 1,0 1,0 1,0 1,0 1,0 RJ Loss (db) 0,5 0,5 0,5 0,5 0,5 RJ loss to Pedestal Base (db) 1,0 1,0 1,0 1,0 1,0 30-M 1/2' FF Cable Loss (db) 3,5 3,5 3,5 3,5 3,5 Receiver input Power Level (dbm) -56,9-55,0-52,2-47,6-45,0 23

36 5 LAPAN-TUBSAT ATTITUDE DETERMINATION AND CONTROL SYSTEM M. Mukhayadi 5.1 ATTITUDE CONTROL STRATEGY The attitude control strategy of LAPAN-TUBSAT is based on the angular momentum management concept. The attitude control is done via 3 reaction wheels and 3 magnetic torquers. For attitude acquisition, 4 solar panels and 2 solar cells are used as coarse sun sensor. Star tracker is employed to provide attitude determination more accurate especially to find the direction of momentum vector. The schematic of the system is illustrated below: Figure 5-1 Configuration of Attitude Determination System The attitude strategy for LAPAN-TUBSAT can be divided into 4 main categories: 1. Hibernation/Momentum Bias Mode, in which the angular momentum is maintained in Y axis which is perpendicular to flight direction. Here the reaction wheel on Y-axis is set to absorb 90% of the angular momentum so that the satellite will rotate at the same direction as the wheel 2. Nadir Pointing Mode, in which the satellite is 3-axis stabilized and the +Z axis is pointed to nadir along the ground track. The spacecraft also has slew capability to point at a certain object on the Earth off-track 3. Interactive Mode, in which the satellite could be rotated in three axis to achieve certain target pointing 4. Tumbling Mode, in which all system is switch OFF except the OBDH and TTC The figure below illustrate a scenario of acquiring an images of region located at some lateral distance from the ground track. The 1 st in the sequence is prior to entering the region to be imaged in which the satellite is out of its hibernation mode and therefore, terminating its rotation around Y axis. Once the rotation has been zeroed, the +Z axis is pointed to nadir. The 2 nd in the 24

37 sequence is rolling the satellite to certain angle to make the camera point to the designated region. The 3 rd in the sequence is putting the satellite back to its hibernation mode by returning the angular momentum absorption back to Y axis and put the Y- axis back to get good sun angle. Such advantage make the revisit time, the interval of time the satellite can make the same picture of a certain area, become shorter than the conventional nadir-pointing satellite. North pole 1 Ground track 2 +Z -Y 3 Region to be shot Sun equator Figure 5-2 Slew Capability of LAPAN-TUBSAT Z trajectory Ground track Region to be imaged Figure 5-3 LAPAN-TUBSAT Target Pointing Figure 5-3 illustrates the scenario of the satellite keep its camera pointing to a certain region in its ground track. Here the satellite initial pitch and pitch rate ( y) is managed so that +Z 25

38 axis would be pointed to the designated point. Application of such picture mode is for example recording moving object in the area or producing stereographic images. The combination of pitch and roll maneuver can also be done to record moving object in or acquire stereographic image of region at some lateral distance from the ground track. During the hibernation mode, except Y-axis wheel, all the attitude control system is switched OFF. Therefore, the power consumed is only to run Y-axis wheel to absorb 90% of the angular momentum. The nutation in this mode would be very minimal since the satellite rotate at very close maximum inertia axis and it is designed to have very small cross product of inertia. LAPAN-TUBSAT also has a free tumbling option (deep sleep mode), in which all system is switch OFF except the OBDH and TTC. Such mode would draw very minimal power from the satellite and the satellite still could be used for store and forward mission. LAPAN-TUBSAT use magnetic torquers as actuation devices together with three reaction wheels. These devices are integrated in three axes of the spacecraft. These torquers use magnetic coils (air coils) to generate magnetic dipole moments. They can compensate for the spacecraft residual magnetic fields or attitude drift from minor disturbance torques. The primary task of these air coils are pointed below: 1) Generating the angular momentum; when the satellite is separated from PSLV, it would have negligible angular momentum. The angular momentum desired is about 80% of the maximum angular momentum controllable by the wheels. The accumulation of angular momentum is done by providing current to the magnetic torquer perpendicular to Earth magnetic field at the equator. 2) Compensating the disturbance torque; the main disturbance torque anticipated in LEO is the effect of Earth magnetic field. Some parts of the satellite, such as the battery casing could be magnetized, and therefore would act like a permanent magnet. Moreover, other devices such as reaction wheel motor employs permanent magnet for rotor. The magnet would be affected by Earth magnetic field and therefore causes attitude disturbance. The magneto-torquers would be activated to compensate such permanent magnet. 5.2 ATTITUDE CONTROL HARDWARE LAPAN-TUBSAT involves several sensors and actuators to run the attitude control strategy explained above. The hardware should meet the requirement for micro satellite that enumerate below. 1) Small mass, small dimensions 2) Low power consumption 3) Electrical interface +12 V and +5 V 4) Low complexity 5) Serial data interface 6) Modular hardware and software 7) High agility of the system The mass and dimension limitation of a micro satellite is also applied to the attitude control system. The smaller dimension of the satellite does not only limit the primary power available, but also the bus tension which is generally has 12 V due to lower number of solar cells per stringer. In order to avoid the applying potential transformers which is made the bus voltage 26

39 worst, the actuators and sensors are required not only have low power absorption, but should be have electrical interface of 12 V or 5 V. The small complexity is achieved by the use as few as possible of a microprocessors with clear architecture which is connected by serial interfaces. By this way, the microprocessors particulars can be assigned task packages. Whereby, the use of only one processor, the complexity would be shifted into the software. There microprocessors generally not over parallel interfaces, so the gyroscope should has serial data interface. The modularity of the hardware gives optimal utilization of the small volume of a micro satellite, whereby the components of attitude control system can be individually integrated. That modularity of the software allows reaction wheels as an actuator in connection with an additional sensor make an acquisition maneuver. The reaction wheels should have several operating modes, such as current control and speed regulation. High Agility of the attitude control system is reached by use of a combination of three gyroscopes and three reaction wheels. They are attached in pairs in the three body-fixed axes of the satellite. The reaction wheels make the unrestricted rotation possible for the spacecraft around three axes. In other hand, the gyroscopes can do independent measurement of the angular speed from one of sources of light (stars, sun, Earth). The other sensor such as a star sensor can be dazzled by albedo of the Earth. The very much important maneuvers for the inertial stabilization of the satellite at the beginning of the over flight is reliable and fast, thereby it is done in less than 10 seconds. Also for maneuvers that commanding by operator in the ground station, those are only reduced by the adjustment of the antenna for video pictures transmission. Figure below show all types sensor and actuator that used by LAPAN-TUBSAT Fiber Optic Gyro Figure 5-4 Attitude Control System Assembly LAPAN-TUBSAT use fiber optic gyroscopes µfors-6 made by company LITEF as a sensor for attitude control system. The specifications of the gyro mention that the gyro is able to read rotation up to 900 o /s which is necessary in satellite application. It has a drift of less than 6 o /s, in which our subsystem level test has indicated that it is actually 3 o /s. In non continuous operation as in LAPAN-TUBSAT, the gyro initialization time become important parameter, in which the specification mention that it is less than 100 ms. The gyro is relatively compact, measuring 9x7x2 cm and only weight 150 gr. The gyro is also consuming relatively low power of 27

40 only 2 W and has RS485 interface. Even though the gyro is designed for aviation purposed, the gyros have been flown in on DLR-TUBSAT and Maroc-TUBSAT, and perform well until today. The gyro utilizes the laser beam transmission in fiber optic spool. One end of the spool is the laser generator and the other end is the receiver sensor. If the gyro is rotated the time for the light to travel from the one end to the other would change proportional to the rate of the rotation. The definition of the positive rotation axis is represented by figure below. Figure 5-5 Definition of Gyro Rotation Axis The variable data interface of fiber-optic gyroscope µfors-6 would be read out by programming or setting one configuration to internal EEPROMS. For LAPAN-TUBSAT application, operation mode of the gyros is configured as Hardware Trigger Impulse. In the selected operating mode (hardware trigger impulse), the gyroscope is triggered by an externally clocked trigger signal, whereby the measuring interval will varies without change the configuration. After that trigger the gyroscope transfers signal with transmission rate Baud. Its signal contains 16 bit angle increment and other information about the asynchronous interface (8 Data bit, parity Odd, 1 Stop bit). This angle increment is referred as angles on the measuring interval. Since the selected utilizable data capacity of 16 bits and the measuring range of ± 8 deg the resolution of measurement is 0, deg/bit Solar Cells as Sun Sensor LAPAN-TUBSAT has 4 solar panels for power generation which are placed on X+, X-, Y-, and Z- side. These solar panels also can be used to determine orientation of spacecraft. Additional solar cells have to be placed on Z+ and Y+ side for monitoring the illumination on all side of the spacecraft. The direction of sun could be estimated by knowing the side which has maximum current. Solar panels and solar cells configuration has been shown in fig. 1. However, this configuration still has ambiguity because it is rather difficult to determine between sun and albedo. Additional data from camera or star tracker are needed to assist sun sensor determine spacecraft orientation Star Tracker Star tracker provides fully autonomous attitude determination. In order to achieve this purpose, it integrates generally an image sensor to take picture from the sky and micro controller to processes and analyses this stellar information. The result of the processing is attitude parameter of the satellite in different format such as Euler Angle or Quaternion. This format has accuracy mentioned by the vendor is 18 arc sec in X axis and 122 arc sec Y/Z (imager axis). The 28

41 star sensor had placed its focal axis corresponds to the X axis and its base plane is parallel to the Z axis and the connector is upturned as shown in figure. 29 Figure 5-6 Reference Frame Definition This star tracker use 512 x 512 pixels radiation tolerant CMOS active pixels as image sensor. Its optical system has 50 mm focal length, so it gives field of view about 14 o x 14 o. The CMOS image sensor STAR250 transform star images through the lens into analogue electrical information. The device is directly controlled by the Hitachi SH7045 microcontroller which also provides a possibility to influence the image generation such as adaptation of the exposure time or the analogue gain. The output of the CMOS sensor is converted to a digital signal before acquisition by the microcontroller. In order to process the new acquired pattern data efficiently, a reference image already stored in memory to eliminate fixed pattern noise. As experience with the micro satellites TUBSAT-A and MAROC-TUBSAT, it is advantageous to compare the actual image with an up to date dark image to correct pixel-blemish and transients caused by radiation effects. This procedure however presumes that there is little coincidence between the actual image and the reference image i.e. the attitude of the spacecraft has slightly changed in the time between two subsequent images by at least 0.15 o (approximately 5 pixel) in the axes perpendicular to the optical axis and approximately 1 o along the optical axis. Bright stars provide clear advantage in the determination accuracy for the calculation of the center of intensity distribution. The STAR250 and subsequent A/D conversion deliver 512 x 512 x 14 bits data for internal image processing by microcontroller. The coordinates of the brightest stars calculated by the microcontroller are based on the average value of all adjacent pixels, which belong to the same star. The star recognition is done by the microcontroller per comparison between the star database and the actual acquired star image. After power on reset, the camera and all control variables are initialized and the star sensor turns automatically in a mode called First Acquisition Mode. In this mode the sensor performs one image of the sky and the whole data in the field of view of the star sensor is processed. At angular rates lower than 0.6 o /s, it has acquisition probability >99.7%. This First Acquisition Mode is activated only for the first attitude calculation and takes generally 900 ms.

42 After First Acquisition Mode is successfully passed over and the attitude of the satellite is known, the sensor turns automatically into a second mode, Tracking Mode. In this mode the image sensor is continuously and completely read out (approximately every 250 ms). Figure 5-7 CMOS Star Tracker The star sensor has a unique unregulated power input interface. The minimum and the maximum input voltage are 9 V and 18 V respectively. The unregulated input power is directly connected to two DC-DC converters, which deliver 6 V analogue and 5 V digital voltages respectively. The 6 V analogue voltages is further filtered and reduced to 5 V. Maximal power consumption during operation is 2.5 W Reaction Wheel and Wheel Drive Electronics The reaction wheel is the actuator of the attitude control system. The reaction wheel essentially consists of a brushless direct current motor with a flywheel, electronics for control of the engine (Wheel Drive Electronics) and housing for installing those components. LAPAN- TUBSAT employs three Reaction Wheels RW303 manufactured by IRE. 30

43 Figure 5-8 Reaction Wheel and WDE These reaction wheels are considerably small for only take dimension of 100 x 100 x 70 mm and weight of 1.2 kg. The reaction wheel has moment inertia of kg.m 2 and can be run up to 6000 rpm. They are controlled by the Wheel Drive Electronics, which could control the amount of current supplied to the wheels, the speed of the wheels, the torque generated by the wheels angular acceleration, or coupled with the gyro sensors could control the angular velocity of the satellite or angular change in pointing direction Air Coil LAPAN-TUBSAT has three air coils that integrated with the main structure. The air coils are used to generate angular momentum in the early orbit phase and compensate disturbance torques during daily operational. The three air coils had been made using enameled cooper wire and wrapped by Teflon. Each coil has number of winding 280, 150, 265 in the X, Y, and Z axis respectively. Since the magnetic induction at altitude 630 km above equator around Tesla, the maximum torque would be generated by coil X, Y, and Z respectively are 1.3 x10-4, 1.6 x10-4, and 1.2 x10-4 Nm. 31 Figure 5-9 Air Coil Assembly on LAPAN-TUBSAT Structure

44 6 LAPAN-TUBSAT POWER CONTROL AND DATA HANDLING A. Widipaminto 6.1 PCDH HARDWARE LAPAN TUBSAT computer system is designed in star configuration with the main computer, called Power Control and Data handling (PCDH), as the central device on the satellite. The PCDH, which is especially design by TU Berlin and Vectronic Aerospace for LAPAN- TUBSAT, consists of a Power Control Unit and a Data handling Unit. The Power Control Unit (PCU) is a module which provides and controls the power for other devices. It provides the circuit for charging the satellite battery, converts unregulated power form battery to +5, +12, -5, and +29 Volt, has 8 fuses, 19 switches, 3 current control systems for the magnetic coils, analog data acquisition (3 inputs for sun sensors, 16 inputs temperature sensors) and a switching port for 2 video inputs. In addition to that, the PCU also have the Main Satellite Switch, which is a voltage limiter to switch ON whole system. The Data Handling Unit controls the switches and fuses via software, obtain telemetry data from data acquisition system, query data/status from system/operation other devices, as well as a central system which handle an interpret commands of other devices. The PCDH features include auto-reset system, system time and timer/delay for switches, as well as delay on stored command and specific user command execution. The PCDH s interfaces for data communication to other devices are eight TTL, four RS232, and four RS422. The processor in the Data Handling unit is a 32 bit SH microcontrollers. The main computer memory capacity is 524 kb external and 4 kb internal RAM, 524 kb EEPROM, and 16 kb PROM. The computer contains the satellite operation system software, which allows direct control of all functionalities via ground station as well highly autonomous operation controlled by time or even triggered tasks. Figure 6-1 LAPAN-TUBSAT PCDH during component test 32

45 The housing of PCDH, which is made from nickel coated aluminum alloy, is electrically connected to common ground of the PCDH system. The housing, which is a box with the outer dimension of 150x150x50.5 mm, is made of three part : Lower Shell, Mid Shell, and Cover to contain the electronics. With the total mass of 1,040 kg, the mechanical interface with the satellite is four mounting trough holes for M4 screws at each corner. During operation mode, the PCDH consumes 53 ma at 14 V. Meanwhile, its recommended operating temperature is -20 to 70 o C. At room temperature (20 o C) the auto-reset system will reset the computer every days. 6.2 PCDH SOFTWARE LAPAN TUBSAT computer use star configuration with PCDH as Central Terminal Unit (CTU) and the other devices as Remote Terminal Unit (RTU). CTU and RTUs each have ID device and command to communicate with each others. The command for RTU (except for Telemetry and Telecommand/TTC unit) always delivered via CTU (to be interpreted and send to the target RTU). LAPAN TUBSAT computer uses 4 bytes protocol for communication between subsystem and devices, which includes getting telemetry data, controlling devices and communicating between the ground station and the satellite. Therefore, the standard for handshaking between RTUs and CTU is the 4 byte protocol. RTU (Camera) From Ground RTU (TTC) CTU (PCDH) RTU (Wheel Drive Electronic) RTU ( Star Sensor) RTU (.) Figure 6-2 Schematics of LAPAN-TUBSAT computer The 4 byte protocol consists of 4 bytes and data. The first byte is the device ID and command. The second and the third byte is the address/memory area from the device. The fourth byte is number of byte which will be read or stored. The communication 4 bytes protocol use half duplex mode so the respond of the commands will be handled after the command has been successfully received. The subsystem or devices in LAPAN TUBSAT which have device ID includes the Ground Station Computer, GS Adapter (Black Box), TTC1 (Telemetry and Telecommand unit 1), TTC2 (Telemetry and Telecommand unit 2), PCDH, WDE1 (Wheel Drive Electronic unit 1), WDE2, WDE3, star sensor, Camera 1 (Sony), Camera 2 (Kappa), Stepper 1 (Sony Camera lens focusing mechanism). 33

46 The main routine in PCDH software consist of two parts : the first initializes the PCDH (both hard and software) and the second part is the main loop. The initialization of PCDH consist of three types : Power Up, Software Reset and Hammer/undetermined resets. The main loop contains the handling interrupt for data request (checking whether any TTCs or EGSE receive any command; if yes masking other input channel and process the command), the command device interpreter and also the power switches timer controller. PCDH as the CTU from star configuration LAPAN TUBSAT have basic commands (Low Level command) and specific commands (High Level command). The Low Level command is to execute basic functions, such as resetting and initializing the system, execute command that has been stored at specific address, and reading data from or storing data to the specific address in RAM or Flash. Meanwhile, the High Level commands are specific commands to obtain telemetry, switch on/off fuse and switches, including setting timer for the on/off time, and access or control other devices (RTU). Highlights of the PCDH s RTU control commands for attitude control system and for store and forward communication are in Table 6-1 and Table 6-2: Command All wheels damping mode All wheels ACS Telemetry All wheels RW Telemetry Read every 10 seconds the Euler angles from STS1 and store them in memory Table 6-1 PCDH attitude control commands Description This command is used to set all wheels on damping mode, to get control loop for all wheel in omega mode (3 axis stabilization) This command is used to get all ACS telemetry data, all mode in control loop (gyro switch on) This command is used to gel all wheels telemetry, only for wheels operation Boot program, This command is used to get euler angle from STS1 every 10 seconds in 6 minutes and store the data in the RAM area. Table 6-2 PCDH store-forward communication commands Command Erase Complete Flash Erase Block nn of Flash memory Check if complete flash is empty Check if nn block flash is empty Read/Write-Test Flash Read/Write-Test RAM Description This command is used to erase all flash memory This command is used to erase block number n fro flash memory This command is used to check if flash empty This command is used to check if block number n of flash empty This command is used to test read/write Flash, if the answer FF Flash is OK, if 00 test failed This command is used to test read/write RAM, if the answer FF Flash is OK, if 00 test failed The telemetry in LAPAN-TUBSAT is classified in 5 categories 1) Power control unit & the analog channels telemetry. The telemetry present the status of power switches and fuses in the satellite, the voltages and current of the battery (main bus) 34

47 and each solar panels and the power consumption (ampere reading) at components of the satellite. The telemetry also presents the reading of temperature sensors on the structure, battery and OBDH. In addition to that the telemetry also presents the current reading of the sun sensors. 2) On-board data handling telemetry. The telemetry presents the status of the system, i.e. total operating time, time since the last bi-weekly reset, and the number of irregular reset since then. The telemetry also presents the timer setting for each component (i.e. when they were supposed to be switch ON and for how long). 3) Attitude control system telemetry. Several modes are set for the ACS telemetry, so that the operator would be to access a. all wheels at one time or one specific wheel. The wheel telemetry consist of the speed (actual and target) and temperature b. all wheels-gyro couples at one time or one specific wheel-gyro couple. In addition to the wheel information, the telemetry consist of the satellite angular speed (actual and target). c. standard information or extended information (including the PID control parameter used in the case of wheel-gyro couple and the I-signal loop in the case of wheel) d. the ACS system register, flag status, software address 4) Star sensor telemetry. The telemetry presents the temperature of the sensor, process log (i.e. process time and flags that may indicate error and time out), as well as parameters that could determine the quality of the reading (i.e. number of recognized star, number of triangle used in the attitude recognition). 5) Stepper system telemetry. The telemetry displays the temperature of the lens and the position of the actuator, which is the necessary information prior to adjusting the lens s focus. 35

48 7 THE PAYLOAD OF LAPAN-TUBSAT A. Widipaminto 7.1 MISSION According to the mission of LAPAN TUBSAT, the payload operation mode consists of scanning mode (plane mode) and interactive mode (helicopter mode). The scanning mode is set by a program (boot program, controlled by PCDH) to control the attitude of the satellite so that the camera will shoot the target on the earth. The satellite will scan target on the earth and move like the plane. The program will be uploaded to the PCDH and will be executed to control the ACS system to keep the camera scanning target on the earth. The accuracy of this mode depends on the reading of the attitude sensors like Star sensor and Sun Sensor. On the interactive mode the attitude satellite is controlled in real time by user/operator with the interactive software from the Ground-Station. The satellite will maneuver interactively so that the camera could shoot the target that the operator desired, analogues to a helicopter hovering over a target. The software interactive could command the ACS system so that the camera will be directed the target and the user will monitor the satellite s respond via the video streaming. The main command in interactive mode is step up/down the pitch/roll angle or the pitch/roll rate of the satellite. The user friendly interface designed for the operator to command the up and down is the PC s cursor. The accuracy/fineness of the interactive mode depends on the flight-hours/experience of the operator, duration contact of the satellite and the link budget communication. 7.2 HARDWARE & SOFTWARE mm focal length camera Figure mm lens, 3 chips camera, lens actuator 36

49 The camera is a Sony Color Video Camera DXC-990P. DXC 990P is analog video camera, which have 3 chip CCD with prism beam splitter as color filter and Exwave HAD Technology, which could enhancement video signal/picture. The CCD chips have 752x582 active pixel area, which with the 1000 mm lens is translated into ground resolution of 6 m and 3,5 km swath. The power consumption of the camera is 7,6 Watt (12 V; 0,66 A). The camera is designed for medical system application and industrial application (i.e. product inspection) and remote surveillance system. The camera electronics components are not dedicated for space environment. Therefore, the C Electrolyte component in the camera is replaced by C Tantalum so that the camera would work in vacuum condition. In addition to that some soldering tin is added to the mounting of the prism so that the rigidity of the connection is stronger for the camera to survive launch vibration. Three chips color cameras used a prism which divides the incoming light rays into their red, green and blue components. Each chip then receives a single color at full resolution. In a three-chip design, light that enters the camera housing is first split into three beams and then focused onto three CCD arrays, each of which has a color filter laminated to the light sensitive side of the array. Therefore, the spectral response function characteristics of the color filters resulted in simple signal processing, very accurate color reproduction and control, and high resolution. The system, however, might have poor low-light sensitivity due to the lower signal levels obtained from beam splitting. Sony has developed the Exwave HAD CCD sensor since in monitoring and surveillance applications, camera sensitivity is one of the most important factors in obtaining an adequate picture in low light conditions. Therefore, low smear levels are necessary, especially for surveillance of areas where bright lights might disturb the image. Smear is caused by the leakage of unwanted light on to the vertical shift register. The smear level of the Exwave HAD CCD is reduced to 1/50th that of the Hyper HAD CCD. This leakage is dramatically reduced because the improvement of the unit cell structure minimizes the unnecessary reflection of the light onto the CCD surface. The conventional sensor structure has an OCL (on chip lens) located over each pixel. The result is that light is concentrated on the photo sensor areas and the sensitivity of the camera is improved. The Exwave HAD takes the Hyper HAD sensor technology a giant step further. The OCL of the Exwave HAD CCD is a nearly gap-less structure, eliminating the ineffective areas between the microlenses. This enables the hole accumulated layer to receive the maximum amount of light. The operation mode of the camera will be in all auto modes, meaning that the gain, white balance and shutter speed will be adjusted automatically by the camera to achieve optimum pictures. The highest (electronic) shutter speed is 0, second, which make it possible for the camera to compensate the blooming/overexposure when flying over cloudy area. The signal format will be set for PAL, which will show 850 TV lines. The salient feature of LAPAN-TUBSAT high resolution camera is that the 1000 mm lens s focal plane can be adjusted in orbit. From the experience of DLR-TUBSAT flight, the focal plane of the high number Cassegrain optics is highly affected by the temperature of the lens s assembly. On DLR-TUBSAT, the lens collimation is fixed on the ground (at room temperature. The temperature on orbit, which is about 10 C less than the room temperature created thermal deformation effect on the lens assembly. As result the focal place is no longer fell at the CCD chip, and therefore, the images taken is slightly blurred. A stepper actuator system is built on the lens, so that its focal plane can be adjusted forward and back by 0,6 mm, which mean that the position of focal plane could be adjusted by total of 3,6 mm. This has guarantee that the lens can be set to infinity focus at temperature range of -50 C to 50 C. When 37

50 the temperature is high, the lens would experience thermal expansion, so that the focal plane might move behind the CCD. To accommodate the phenomena the actuating rod is extended, the potentiometer reading decrease and the lens is shortened, so that the focal plane could be brought forward. The inverse is for low temperature. The Focus Control System is the controller for adjusting focus of Sony Camera. This device consist of microcontroller as main controller, stepper motor as actuator and the sensors for monitoring status temperature and status current position of focus and joint arms (to translate the movement from one axis to another). The Block Diagram of the Focus Controller System is illustrated bellow : Temperature Sensors : LM335 Position Sensor : Potentiometer Waycon LZW1 ADC Bytes from PCDH SCI OutputPins Power Transistor Stepper Motor : HSI Actuator Controller Hitachi SH7145 Figure 7-2 Block Diagram of LAPAN-TUBSAT Focus Control System Actuator Focus Controller System used Processor Hitachi 32 bits SH 7145 as main controller for command handling, set step the motor stepper and read data from the sensors. The System connected with PCDH via Serial Communication Interface (SCI) which internally built in the processor and have standard communication setting for devices in the 4 byte protocol (Asynchronous, bps, 8, N, 1). The system has two kinds of sensors, first is the temperature sensors used LM355 and second is position sensor used Potentiometer Waycon LZW1. 5 temperature sensors (LM335) placed on several places in the platform. The temperature sensors distributions are on the stepper electronic, on the Sony, camera, on the rear part of the lens, on the middle part of the lens, and on the front part of the lens. The sensors connected with Analog Digital Converter (ADC) that also built in the processor. The Actuator used stepper motor HSI which could deliver of maximum 23 N actuating force. The system set the motor stepper to move right step or left step by sending a sequence of bit (high/low) as phase sequence of motor stepper via output pins from the microcontroller Focus Control System Software In LAPAN TUBSAT, the Focus Control System will receive command via PCDH. If the bytes/command is valid (checked by the software) then the command will be interpreted and executed. 38

51 There are two kinds of commands in the systems, i.e. actuation request and telemetry request. In the actuation request, the number of steps to be executed is defined in 3 modes, i.e. 8,, and Before the actuation is executed, the target/final position is checked whether it will exceed the maximum position or not. If the target position is higher that indicated numeric (from potentiometer position) unit of 840 or less than 320 then the command will be not executed and the status register will record the command is not executed. The long telemetry data describe the temperature of Stepper Electronic, temperature of Sony Camera, temperature of Stepper/Motor, temperature of Objective (Rear), temperature of Objective (middle), temperature of Objective (front), Potentiometer Position and Status Register. Meanwhile the short telemetry data only describe the Potentiometer Position. The operation mode of the stepper motor is : 1. ask for stepper telemetry, which include the last actuator s position and the temperature of the lens 2. based on the temperature, the operator would know that the lens have expanded or contracted and therefore could made necessary adjustment In order to survive the space condition, the lubricant in the bearing of the DC motor is replaced by vacuum grease (fluorinated fomblin). Other moving parts contact area in the lens and the actuator system is covered by Teflon ring/layer to reduce friction (as bushing) mm focal length camera The 50 mm focal length camera is to get the wide angle view before a particular site is needed for more detailed picture is taken (zoom in). Figure mm lens, kappa camera, baffle and mounting system The camera is a KAPPA Video (PAL) Camera CF 142. CF 142 is analog video camera, which have 1 chip CCD with color filter and Exview HAD CCD, which could enhancement video signal/picture. The CCD chips have 752x582 active pixel area, which with the 50 mm lens would translate ground resolution of 200 m and 81 km swath. The operation mode for the camera is in all-auto mode (gain, white balance and shutter speed). The maximum (electronic) shutter speed is 0, second. The PAL video format produce will have 480 horizontal lines. The power consumption of the camera is 3 Watts at 12 V. 39

52 8 LAPAN-TUBSAT COMMUNICATION SYSTEM 1: ON- BOARD HARDWARE W. Hasbi Communication system of satellite is an important system in the satellite. The function of the system is to transmit data to the ground station or receive command or data from ground station to perform the satellite mission. Therefore, the design of the communication system, i.e. frequency, type of modulation, or data rate, etc is highly depend on the mission. The frequencies used for satellite communications should be selected from bands that are most favorable in terms of power efficiencies, minimal propagation distortions and reduced noise and interference effects. These conditions tend to force operation into particular frequency regions that provide the best trade-offs of this factors. Based on the LAPAN-TUBSAT satellite mission, there are two type of communication for the satellite. The first is for the interaction with the ground station so that command can be received by the satellite and telemetry or housekeeping data of the satellite can be received by the ground station. This system is also used for data store and forward mission. The second is for the surveillance mission, in which video streaming will be transmitted to the ground station. These two missions of LAPAN-TUBSAT are communicated via UHF and S-band frequency. The usage of UHF frequency as communication gateway is due to the simple protocol of LAPAN-TUBSAT and its efficient house keeping data, so that it is enough to use lower frequency, which means lower data rate, even in half duplex mode for communication reliability. Such simplicity of communication gateway gives benefit for efficiency in power budget and also reduces complexity in component, which eventually reduce cost of development. In the ground station side, only a simple modem and decoder called ground station adapter is needed to decode data from LAPAN-TUBSAT. For its video surveillance mission, LAPAN-TUBSAT uses S-band frequency, since the mission s data should be communicated in real time so that satellite operator could directly aware on the events happening on the subject observed. Again, to for simplicity an S-band transmitter with analog FM modulation is used for the data transmission purpose. Such communication system is similar to the typical television broadcasting, so that in the ground station side, only S- band receiver and an analog PAL TV decoder, and a TV set are needed to display the video from the satellite. 8.1 TT & C TRANSCEIVER The devices generate and analyze the code of command, modulate, demodulate and send & receive command via RF signal from LAPAN-TUBSAT satellite to Ground Station or vice versa. The hardware/software is derived from the TTC of TUBSAT generation. In the previous TUBSAT generation, the TTC device also functions to collect telemetry data from other devices and Power Control Unit (PCU) function. Such function, however, is no longer used in LAPAN- TUBSAT. That telemetry of devices and PCU function, instead, is done directly by PCDH device of LAPAN-TUBSAT. These TTC has internal command which consist of, reset, execute, read & store (4 byte protocol). TTC has feature for changing frequency and codeword with change the value in RAM area of TTC. However it s recommended to not changing the frequency to far from its default frequency due to antenna VSWR. If frequency is changed too far then it may cause problem with TTC s transmitter as reflected power will be too high also. These TTC always be automatically 40

53 switched on by PCDH every 10,5 hours. This is to make sure so that TTC will always ON, even after drop of its fuse. Figure 8-1 LAPAN-TUBSAT TTC unit LAPAN-TUBSAT has two units of TTC which work simultaneously. However, once one of the TTC works (i.e. receive command), it will send a command to the other TTC to mask its function. When operators send a command via ground station to satellite, the command will be received and demodulated by TTC. Then, the TTC will check its CRC and code word. If those steps were passed, then TTC will send acknowledge confirmation ( beep tone ) code to Ground Station so that operator would know that command is received. After that TTC will check device ID number of the command whether this command for TTC or not. If command is for TTC then command will be executed in TTC it self. If the command is not for TTC then command will be passed to PCDH. The PCDH will then process and forward the command to appropriate device based on its ID. If the command request answer or telemetry of any device, then device will send its answer to PCDH. After that PCDH then forward the data or telemetry to same the TTC in which the command to PCDH came from. The TTC then add CRC, code word, modulate and send the telemetry data to the ground. The TTC hardware consists of a 16 bit Hitachi H8/536 processor, FFSK modem and UHF transceiver. RF power output of TTC is about 3,5 watts up to maximum 5 watts at 50 Ohm impedance. Mass of the TTC per unit is 515 grams with the dimension of 92 x 93 x 38,5 mm. The RF side in TTC uses frequency of 437,325 MHz. This frequency is used based on IARU (International Amateur Radio Union) and Indonesian Frequency Authority recommendations in amateur frequency band. Communication between ground station and satellite is done in Half Duplex mode. The RF power output about 3,5 watt. Modulation of TTC is in FFSK modulation which 1200 Hz as 1 and 1800 Hz as 0 for its modulation. 41

54 Figure 8-2 LAPAN-TUBSAT UHF antenna The UHF antenna was made of stainless steel rod of 2,5 mm diameter and total length (including connector part) 128 mm. The antenna was designed for carrier freq of 436,075 MHZ. The polarization of the antenna is linier, the gain 0 dbi, and the antenna pattern is toroid in horizontal plane. The return loss of this antenna is about 25 db at 436,075 MHz, however since IARU requested to change the frequency to 437,325 MHz then the return loss will be about 24 db (VSWR 1,13:1) or only 0,0160 db transmission loss or only 0,375% power will be reflected. Test of the TTC devices were done with measurement of the power output of the TTC, TTC functional test with data communication, simplify near field & far field test and also temperature & vacuum test. Based on test result, it is concluded that the TTC was function properly and ready to launch. 8.2 S-BAND TRANSMITTERS Figure 8-3 S-band transmitter and antenna The S-Band Transmitter transmits the video PAL signal from LAPAN-TUBSAT camera to the ground station for real time visualization of one location on earth. This S-band transmitter operate in frequency 2220 MHz. Modulation which is used to transmit the video signal in Frequency Modulation (FM) with deviation of 8,5 MHz. Input for the transmitter come from multiplexer of PCDH (Power Control & Data Handling) of LAPAN-TUBSAT which select video signal from two cameras should be transmitted. The video signal is PAL standard which have frequency from 10 Hz to 5,5 MHz. Based on this then occupied bandwidth which is used is 27 MHz. RF power output from this transmitter is 3 watt. 42

55 Frequency which is used for LAPAN-TUBSAT video transmission is 2220 MHz. This frequency was acknowledged by ITU (International Telecommunication Union) and Indonesian Frequency Authority recommendations in space scientific band. Modulation of the transmitter is in analog frequency. The S-band antenna is a helix antenna, designed for frequency of MHZ. The polarization is RHCP; the gain is 8 dbi and the antenna beamwidth is For this helix antenna, return loss about 25 db (VSWR 1.12:1) in which only db transmission loss or 0.324% power will be reflected. S-band transmitter and its antenna devices were tested with measurement of the power output of the transmitter, functional test with video transmission, simplify near field & far field test and also temperature & vacuum test. Based on test result, it is concluded that the S-band transmitter system was function properly and ready to launch. 43

56 9 LAPAN-TUBSAT COMMUNICATION SYSTEM 2 : GROUND STATION A. Rahman, E. Nasser, W. Hasbi, M. Ichsan The first ground station for LAPAN-TUBSAT satellite in Indonesia is developed in Rumpin. Rumpin Ground Station is the primary station for operation and controlling LAPAN-TUBSAT satellite. Figure 9-1 LAPAN-TUBSAT/MODIS ground station in Rumpin 9.1 GROUND STATION ADAPTER Ground Station adapter is one of the devices of LAPAN-TUBSAT system. The function of the device is as modem and buffer, which together with the RF systems in the G/S, communicating to LAPAN-TUBSAT. In the system configuration, the ground station adapter stand between the PC on the G/S and TTC on satellite side. The G/S adapter consists of FFSK Modem, Analog Packet Data Interface and 16 Bit H8/536 Microprocessor, which includes data and program memory. The modem is configured at 1200 bps and half duplex setting, and the Microprocessor control modem and analog data interface. The G/S adapter also uses reset generator and voltage generator to control the power supply in its system. The adapter use RS232 interface with baud rate bps, 8 bit, 1 stop bit and none parity. The DB9 connector only uses 3 pins for Rx, Tx and Ground. For the Analog Data Interface to the UHF transceiver, a DB9 connector is used, with 3 pins as Packet Data, Push-to-Talk (PTT) and Receive 1200 bps. The G/S adapter receives input command from G/S PC via serial communication interface. The command is then handled by H8/536 microprocessor, which its software base on four byte protocol also. After the data and command packed with byte synchronizer, code word 44

57 and CRC code, then data will be sent through synchronous communication to FFSK Modem. The modem will modulate the packet and in parallel the microprocessor control the Analog Packet Data Interface to enable the PTT to transmit the data through Transceiver radio. If G/S adapter receive data from TTC, data and command will be demodulated by modem, and checked for codeword and error code (CRC). If the data and command is valid, data will be stored temporarily in buffer before being sent to G/S PC. After validating the communication protocol (handshake) between G/S adapter and G/S PC, then G/S adapter send the data to G/S PC for visualization. G/S adapter device was functionally tested in the Ground station system with data communication to LAPAN-TUBSAT satellite. Based on test result, it is concluded that the G/S Adapter was function properly. 9.2 GROUND STATION PREPARATION & TEST According to LAPAN-TUBSAT satellite mission and requirement, block diagram of the ground station is prepared as follow: Figure 9-2 LAPAN-TUBSAT G/S flowchart Both of the ground station has prepared and tested. Test of the ground station is done using DLR-TUBSAT satellite which has similarity of communication system with LAPAN- TUBSAT satellite. Test of ground station using DLR-TUBSAT satellite was to make sure that ground station will be ready to receive LAPAN-TUBSAT satellite. The tests were done on 22 nd April 2005, in which the visibility is as follows when DLR-TUBSAT attitude (camera axis) set for anti-sun pointing. 45

58 Figure 9-3 LAPAN-TUBSAT visibility on 22 April :19:00 WIB Figure 9-4 Video frame from DLR-TUBSAT above Indonesia taken from Rumpin The video frame is received from 50 mm black & white camera of DLR-TUBSAT, which is transmitted in real time to Rumpin Ground Station on 22 nd April Most of the picture is white due to over exposure of the camera because of cloudy situation above Indonesia which reflect light from the sun. For LAPAN-TUBSAT satellite this over exposure problem is prevented with higher shutter speed compare with DLR-TUBSAT camera and also with higher f/d of the camera s lens to limit incoming light intensity. This end to end test from LAPAN Ground station and DLR-TUBSAT also verified link budget according to above link budget calculation. 46

59 10 MECHANICAL AND ELECTRICAL INTERFACE OF LAPAN-TUBSAT R.H. Triharjanto, W. Hasbi 10.1 LAPAN-TUBSAT STRUCTURE Requirements LAPAN-TUBSAT structure is the main mechanical interface. The general functions of the satellite structure are to mechanically integrate the satellite components and to protect the components from the load or environment during the launch and orbit. The load during the launch is mainly mechanical, static and dynamics. Meanwhile in orbit, the main load comes from the effects of radiation (thermal and charged particles). The structure of the satellite has to be stiff enough to ensure the fixed position and pointing of each component of the satellite. For example the pointing direction of the star sensor, reaction wheels, gyros and coils, as according to the operational specification of the satellite. Since LAPAN-TUBSAT is to be launch by pigyback system, in which it will be seated in space available in the electronics bay of a rocket that will launch a big satellite, the volume and mass constraint is one of its main provision. For pigybak launch with PSLV, the mass limit is 150 kg and the outside envelope of the satellite (including all its protruding elements) should be less than 700 x 700 x 850 mm. In addition that, the satellite s center of gravity should be higher than 450 mm from the rocket adapter and has to be within the radius of 5 mm from the center of the axisymetric adapter. The provisions for the strength and stiffness of the satellite structure are also based on PSLV flight load. Those are able to withstand acceleration up to 7 g in the rocket s longitudinal axis and 6 g in the rocket s lateral direction. As for the stiffness, the lowest natural frequency of the satellite should be more than 90 Hz in the rocket longitudinal direction and more than 45 Hz in the rocket s lateral direction. In addition to all the mentioned requirements, the operation mode of LAPAN-TUBSAT require the satellite structure to be designed so that the satellite would have maximum moment of inertia in the satellite s Y axis and minimal cross product of inertia. This provision is to minimize the satellite nutation during the angular momentum transfer operation. LAPAN-TUBSAT relies on its structure to control the temperature of its components. Therefore, the structure is designed to conduct heat from elements that generate heat or being heated by radiation to cooler pats of the satellite. The last provision of the design of LAPAN-TUBSAT structure is that its components should be able to be manufactured in moderate manufacturing facilities Design The design of LAPAN-TUBSAT structure is performed following the requirements mentioned above, in which the optimal result is the dual compartment system. The function of the compartments is to house the components of the satellite. It was made of a box with 450 mm in length (x axis) and 450 mm (z axis) in width, which is became the baseline of the structural design. The dimension is chosen to accommodate the longest 47

60 component, i.e. the Sony camera mounted with 11/1000 mm Casegrain lens and still left some envelope for the protruding UHF antenna in the PSLV s piggyback envelope. In order to fit all the components inside, which has various dimensions, 2 shelves system, called upper compartment and lower compartment (based on its position on the launcher) is created. This design is made to provide maximum access to the component while harnessing and testing. The upper compartment is design for the thinner components and the lower compartment is designed for the thicker components. The height constraints for the lower compartment is the height of the lens and its mounting platform, meanwhile the height constraint on the upper compartments is the diameter of the battery plus its mounting system. Figure 10-1 Upper compartment The main structure consists of 7 aluminum alloy plates of 10 mm thick. The plates are black anodized for thermal characteristic purposes. Several cut outs is made so that the harness could go from one compartment to the other and to provide windows for the cameras to look outside the satellite as well as for the power and signal cables to go through. The upper compartment contain the battery, power control and data handling system (PCDH), a camera with its 50 mm lenses, one telemetry-and-telecommand (TTC), and an air coil. In addition to that, two more air coils (placed orthogonally) will occupy some space on the lower and upper shelf. The lower compartment contains the attitude control system, one (TTC) system, a payload camera with its 1000 mm lenses and S-band system. The launch adapter will be placed on the lid of the lower plates (or called y minus plate). 48

61 49 Figure 10-2 Lower compartment The placements of the components are done to get the center of gravity as much as possible at the center of x-z geometry and to minimize the length of its harness, especially signal cables. For example, the reaction wheels and batteries are placed on the opposite sides from Sony camera platform for center of gravity purposes. The placement of S-band transmitter and TTCs are governed by their antenna locations. The components of attitude control systems are held close to each other to minimize wiring. The gyros are directly connected to the structure so that the heat generated could be dissipated via conduction. The three wheel drive electronics, which a have thin shape, are stacked to minimize volumetric used. The design of the 3 air coils required the use of maximum space for the coil s loops. Therefore, special cut outs on the middle plate is made to accommodate the X and Z coil to run from one compartment to the other. The joining of the main structure s plates use M5 bolts and for reinforcing the joins against shear loading, shear pins are allocated, four on each joins side that considered being critical and two on the rest of the joins. From the structural load point of view, the most critical part is on the join between the middle plate and the four vertical plates and the joins on the corners the lower plates. With the estimation of 6 g static lateral load, using steel pins of 5 mm diameter, which protrude 5 mm to Y plus plate and 10 mm to X and Z plates, it was found that the use of 16 pins on Y plus joins

62 would give theoretical safety factor of 3.5. Meanwhile, using the same pins and 7 g static longitudinal load, it was found that 4 pins on each side of the middle plate would give theoretical safety factor of 5. The battery mounting has to ensure that the batteries, which have pressure vessel shape, would be rigidly attached in the satellite, while at the same time allows some tolerance for the volumetric expansion of the vessel in which the pressure would build up during charging. It is desirable that the heat generated during charging can be removed from the batteries so that its live could be prolonged. However, the batteries casing is not electrically insulated and therefore could not be grounded. Meanwhile a thermally conducting material such as metal is also electrically conductive. Therefore, the battery mounting is made of fiberglass, which is less stiff than the batteries stainless steel casing and an electrical insulation. For heat dissipation purposes, the batteries are painted black (maximum heat radiation). Figure 10-3 Battery mounting The mounting for Sony camera and its 1000 mm lens is the most complex part of LAPAN-TUBSAT structure. The purpose of the platform is to damp the vibration and shock load during transportation and launch so that the sensitive optics can be protected and accommodate the focusing mechanism. The mechanism is designed to adjust the focal plane of the lens in orbit, which may be shifted due to the thermal expansion/contraction effect on the lens mounting. The focus adjustment is done by rotating the middle part of the lens, which sat on thread from the front and aft part, so that the distance between the primary and secondary mirror can be changed. For that, the lens mountings have Telfon bushings (painted gold in figure). The coupled rotatingaxial sliding action on the middle part of the lens is produced by converting axial displacement from a servo drive via series of joins, again, with Telfon bushing. The selection of Teflon is made since conventional lubricant would outgas in vacuum. The damping action in the platform is done by a number of steel springs attached on the bottom and left side of the platform, which are connected to the main structure of LAPAN-TUBSAT. 50

63 Figure 10-4 Exploded view of Sony camera platform In order to see stars the star sensor has to point its camera to space and away from the bright light, which could become a reading noise. The component specification mentions that the direction of incoming bright light source should be more than 30 o from normal. Since the only side that does not have solar panel and does not designated to point to Earth is plus Y side, which has the upper part of PSLV separation attach to it, special platform is designed to elevate its position so that the sensor s field of view is not obstructed. This platform also designed to make the star sensor view axis inclined 30 o from y plus axis to guarantee that the sensor will not be blinded by Earth s albedo when the angular momentum of the satellite is placed perpendicular to the orbital track. The mounting of the sun sensors are to elevate the sensor to avoid being in the shadows from other protruding parts, which the camera baffles the plus Z side and the upper part of PSLV separation ring on the plus Y side. To reinforce the strength and stiffness the mounting of the Wheel Drive Electronics, which their housing mount only depend on 4 long screws to accommodate 3 stacked Wheel Drive Electronics, a steel C-clamp mounting is made. The harness is attached to the structure using screws and Teflon cable ties. The gap between the components is designated to be used to attach the harness to the structures. Several cut out is made on the middle plate so that the harness can run from one compartment to the other Dynamic Characteristics The structural dynamic design constraints of the mechanical system of the satellite are able to accommodate structural requirement for PSLV, which are 1st resonance frequency in the rocket longitudinal axis > 90 Hz and 1st resonance frequency in the lateral axis > 45 Hz. Therefore, the structural dynamic characteristic data of the satellite needs to be evaluated are the natural frequencies and mode shapes of the satellite structures. From the design above, the satellite s structure dynamic characteristic analyzed and tested. 51

64 In the FEM modeling, the main structures of TUBSAT-LAPAN is made by Al-Alloy 2024 T351 material (E = 7.6x10 10 N/m 2, Poisson ratio = 0,33, density = 2768,4 kg/m 3 ). The satellite components in upper compartment are replaced by 9,3 kg dummy load made by Al- Alloy 2024 T351. The components in lower compartment are replaced by 17,02 kg dummy load with the same material. Using dimension based on 293,44 x 293,44 mm, we find the height of the both dummy loads are 39,42 mm and 72,15 mm, respectively. The modeling for both the UHF antenna uses Stainless Steel materials, which is their real material. The dimension of UHF antenna is 20 mm diameter in the root (30 mm height) and 3 mm diameter for the rest (200 mm height). Meanwhile, the cylindrical dome cover for S-band helical antenna has 65 mm diameter and 88 mm height, and is modeled using Al-Alloy 2024 T351 material. The rest of the protrusion elements such as the lens baffles both cameras sun sensor mounting as well as are also modeled in FEM by Al-Alloy 2024 T351 material. The FEM model of the satellite structures consists of 1982 elements and 2812 nodes. This model is shown in Figure Since the joins in LAPAN-TUBSAT structural components are made with large safety margin, in the FEM modeling it is regarded as the material is perfectly joined or sharing nodal points. The launch adapter is placed on the lower plates of satellite (Y minus plate) and fixed using 12 bolts. Therefore, the modeled constraints is fixed supported (6 DOF lock) on 12 nodes at the 12 bolts location. The normal mode analysis is carried out using Nastran software and the result for the 1 st seven resonance frequencies are at 52,29 Hz (1 st natural freq. for UHF antenna at Y + plane in xy direction), at 52,292 Hz (1 st natural freq. for UHF antenna at Y + plane in xz direction), at 52,30 Hz (1 st natural freq. for UHF antenna at X + -plane in xz direction), at 52,31 Hz (1 st natural freq. for UHF antenna at X + plane in xy direction), at 104,09 Hz (1 st natural freq. of satellite structures in lateral direction, x axis), at 106,41 Hz (1 st natural freq. of satellite structures in lateral direction, z axis) and at 151,47 Hz (1 st natural freq. of satellite structures. in longitudinal direction, y axis). V1 C1 Y Z X Output Set: Mode 1, Hz Deformed(19.13): Total Translation Figure 10-5 Normal Mode for frequency Hz 52

65 V1 C1 Y X Z Output Set: Mode 5, Hz Deformed(0.258): Total Translation Figure 10-6 Normal Mode for frequency Hz The analysis results depict that the lowest frequency occurs at UHF antenna structure. The lowest natural frequency is Hz in lateral direction and Hz in longitudinal direction. From these results, it is concluded that the satellite structures can accommodate structural dynamic requirement for PSLV, which 1st resonance frequency in longitudinal axis >90 Hz and 1st resonance frequency in lateral axis > 45 Hz, and therefore, the components in satellite compartments will be safe from the resonance frequency of launch vehicle. The normal mode shapes of the 1st natural frequency of TUBSAT-LAPAN micro-satellite structures in lateral direction as well as in longitudinal direction are shown in Figure Structural dynamic characteristic of TUBSAT-LAPAN micro-satellite in free flying condition is also evaluated for separation clearance analysis. Therefore, the normal modes analysis is made for no-constraint condition. The results show that the 1 st natural frequency for satellite structures is less than 0,00032 Hz. The FEM model is also used to perform Coupled Load Analysis, so that the load on the satellite can be estimated. The study is made by the launch authority Testing The purpose of the test is to verify whether LAPAN-TUBSAT will survive the mechanical load during the launch in PSLV. In addition to that, the test equipment is used to measure the natural frequency of the satellite, so that the satellite could be accepted by the launch authority. The test is done on DLR/Astrofeinwerk facility in Berlin, in May

66 Figure 10-7 Test setup for Y axis vibration The test requirement is specified by the launch authority, ISRO, as mentioned in the interface control document, i.e. Table 10-1 PSLV sine vibration test requirement Frequency (Hz) Level Axial axis (y) 5 8 mm (0 to peak) ,5 g Lateral axis (x & z) 5 10 mm ,5g Sweep rate 4 octave/min Table 10-2 PSLV random vibration test requirement Axis Frequency level 20 0, ,002 x, y, z 250 0, , ,009 level 6,7 g rms duration 1 min/axis In addition to that, for LAPAN-TUBSAT to be accepted in the PSLV mission, its natural frequencies have to demonstrated to be higher than 90 Hz in PSLV s longitudinal axis and higher than 45 Hz in PSLV s lateral axis. 11 accelerometers were installed on the body of the satellite to read its structural dynamic responses. Since LAPAN-TUBSAT Sony camera platform has a special damper, one accelerometer is installed on the Sony camera lens Natural frequency (resonance) test were done on the test subject prior and after every test sequence, in order to detect the changes in the inertia system of the test subject (any structural 54

67 failure or deformation the satellite would change the inertia system). The resonance test were done using Hz with level of 0,2 g and sweep rate of 2 oct/min. Axis X Y Z Table 10-3 Result Of Resonance Search Test Accelerometer Position Before Sine test After Sine / Before Random test After Random test Main Structure f0 = 79 Hz/ Q = 4 f0 = 74 Hz/ Q = 4 f0 = 75 Hz/ Q = 4 Camera Baffle f0 = 82 Hz/ Q = 9 f0 = 78 Hz/ Q = 10 f0 = 78 Hz/ Q = 10 Main Structure f0 = 148 Hz/ Q = 6 f0 = 148 Hz/ Q = 5 f0 = 148 Hz/ Q = 5 Camera Baffle f0 = 99 Hz/ Q = 10 f0 = 102 Hz/ Q = 15 f0 = 100 Hz/ Q = 14 Main Structure f0 = 73 Hz/ Q = 3 f0 = 72 Hz/ Q = 3 f0 = 72 Hz/ Q = 3 Camera Baffle f0 = 52 Hz/ Q = 5 f0 = 53 Hz/ Q = 5 f0 = 53 Hz/ Q = 5 The result shows that there are no structural deformations or failure in LAPAN-TUBSAT. Minor change in the natural frequency of Sony camera platform on the x-axis test is due to the damper settle at slightly different configuration, which is known to be its function. Visual observation also confirmed that there is no structural changes happen in the satellite. Resonance at about 28 Hz is noted on the reaction wheels, in which the wheels manufacturer confirmed that it is the frequency that the wheels damper system is designed for. Both the FEM modeling and the resonance test show that LAPAN-TUBSAT structure has fulfilled the requirement of PSLV launch. The difference in the frequencies from the modeling and the test is due to the simplification in the modeling (i.e. components modeled as 2 solid blocks rigidly attached to the middle plate and the use of one material property) LAPAN-TUBSAT HARNESS LAPAN-TUBSAT harness is the main electrical interface. The function of the harness is to connect the satellite s components or subsystems so that the system could function properly. The harness should ensure the connection for all of the satellite components are acceptable, even though it has to withstand the vibration, G-loads, vacuum and thermal cycling imposed by space environment. The harness should ensure that the signal cables are well insulated from noise and the length is minimal to avoid signal loss. It is also designed to avoid inducing magnetism in the satellite which could affect the satellite s attitude. In LAPAN-TUBSAT, there are total of 149 connectors to from various components and subsystem to be connected by harness. The harnessing activities include cable routing design, soldering, and testing. The cable routing in the satellite structure was design so that it would accommodate the load/stress during launch while having optimal length of the cable and avoid power loop to prevent inducing magnetic field. To ensure good quality of contact, the soldering of the cables into the connectors use controllable temperature soldering tools, standard tin solder, flux, glue and other tools. Also to assure proper and satisfactory quality of soldering and connection there are few step of quality control mechanism, which includes series of connectivity tests and functional tests. 2 mm Teflon cable is used for the signal and power cable and Teflon coated signal cables for the RF and video signal. The connectors used are mainly military specification (Mil-spec) Sub-D connectors. Teflon cable mounts and Teflon cable ties also are used to attach the harness to the satellite s structure. The RF cable used to connect high power signal from the transmitter to the antenna based on criteria of impedance, losses and flexibility for routing. In order to further minimize the loss and the stress from launch load to the cable, they are cut exactly the length of the needed connection. 55

68 Figure 10-8 LAPAN-TUBSAT Main harness including battery connectors Figure 10-9 LAPAN-TUBSAT harness installed on Lower Deck Including in the main harness system is the satellite temperature sensors. The 9 sensors, LM335 TO-46 type, are located at the middle plate, battery, S-band transmitter, and all the 6 side plates of the satellites. The objective of the sensors is to monitor the temperature in the satellite. The harness was been verified and tested with functional test as well as with vibration test according to PSLV requirement. Based on the test result, the quality of harness is satisfactory. 56

69 11 LAPAN-TUBSAT LAUNCH CAMPAIGN R.H. Triharjanto, S. Hardhienata, A. Rahman, W. Hasbi 11.1 LAUNCH PLAN The launch of LAPAN-TUBSAT is piggyback on Indian PSLV (Polar Satellite Launch Vehicle) mission number C7. The launch contract was signed on September 2004 between LAPAN and ANTRIX (Indian Space Research Organization/ISRO s commercial branch). The payload for the mission is Cartosat-2, a high resolution remote sensing satellite, and SRE (Space- Capsule Recovery Experiment), a spacecraft to perform micro-gravity and Earth re-entry experiment. C7 mission is the first time that the ISRO launch two main payloads. The launch is done from Sriharikota (Satish Dawan Space Center 13 47'North 80 15'East). The intended orbit is 635 km Sun-synchronous orbit (inclination 97,9 o ), and the equatorial crossing is about 10 AM. The launch configuration is as follows. Figure 11-1 PLSV-C7 payload bay 57

70 The launch is initially set for September 2005, and therefore the satellite is made to be ready on July However, technical problems on the main payload (SRE and Cartosat-2) made the launch to be delayed. Further, delay is announced in the 1 st quarter of 2006, as the main payloads are not ready until 2 nd quarter of The mounting configuration has also changed from originally tilted 15 o at the issuance of launch contract to 45 o in the mid of 2005, when LAPAN-TUBSAT has been completed. In the new configuration, the radial clearance between LAPAN-TUBSAT and acoustic blanket in PSLV s fairing is 85 mm. Such changes resulting into significant change in the mechanical load during launch; fortunately, LAPAN-TUBSAT structure was over-designed in the terms of strength to accommodate the heat capacity and inertia requirement. LAPAN-TUBSAT is mounted to PSLV using IBL-298, ISRO s ball-lock separation system for auxiliary payload under 100 kg. Fitting check of LAPAN-TUBSAT mounting holes with rocket interface is done in Berlin on September Figure 11-2 Fitting check with IBL-298 As piggyback payload, LAPAN-TUBSAT is to be ejected the last from PSLV s upper stage. The first to be separated is Cartosat-2, followed by opening the DLA (dual launch adapter), after performing collision avoidance maneuver. The attitude maneuver is then repeated for SRE separation, and finally for LAPAN-TUBSAT. 58

71 11.2 LAUNCH CAMPAIGN Figure 11-3 LAPAN-TUBSAT separation scenario Special container is designed to transport the satellite from Berlin, Germany to Shriharikota, India. The container design uses the heritage of TUBSAT and BIRD container made by Astro-und Feinwerktechnik. The main function of the container is to provide vibration and impact damping as well as contamination during transport. Figure 11-4 LAPAN-TUBSAT container being closed prior to shipping Since the launch is delay for considerably long time, LAPAN-TUBSAT has to be stored at ISAC (ISRO s satellite center) in Bangalore, India, for several months. During its stay in India, the satellite undergoes storage maintenance mode since the satellite s power system has been closed as it is prepared for launch in September As all the spacecrafts are ready at the end of November 2006, cyclone season hit Sriharikota. The launch window is then decided to be January, Another nanosatellite from Argentine, Pehuensat, has been added to PSLV C7 payload. The satellite is bolted to the DLA. 59

72 Since LAPAN-TUBSAT launch mode is with the condition of open circuit due to battery drained, the satellite battery is discharged on December 27 th, LAPAN-TUBSAT is moved to PLSV s assembly building on the morning of December 29 th, 2006, in which ISRO s engineers performed good-luck function to the satellite by breaking of coconuts in front of the satellite s transporting truck and distributing sweets. After 41 m crane ride, LAPAN-TUBSAT finally made it to PSLV-C7 equipment bay. Figure 11-5 Integration of LAPAN-TUBSAT to PSLV Figure 11-6 PSLV C7 fairing closure 60

73 LAPAN-TUBSAT is assembled to PSLV on December 30 th, 2006, and the payload fairing id closed on January 2 nd, The launch 50 hours countdowns began on the morning of January 8 th, Exactly on 9:23 morning at January 10 th, 2007, PSLV C7 lifted-off, flying initially to South-East before turning to 190 o direction, bringing the four satellites into orbit. Figure 11-7 Launch of PSLV C7 Carosat-2 is separated from PSLV 16 minutes after the lift-off and LAPAN-TUBSAT is separated about 3 minutes after that. At the moment of separation, LAPAN-TUBSAT was flying at the altitude km, over the Indian ocean (38 o 21 South, 72 o 39 East), at the speed of 7,5 km/s. 61

74 12 EARLY OPERATIONS OF LAPAN-TUBSAT M. Mukhayadi, E. N. Nasser, A. Rahman, R.H. Triharjanto 12.1 FIRST ACQIUSITION On January 10 th 2007 LAPAN-TUBSAT was launched into sun synchronous orbit at an altitude of 642,5 km with 97,9 degree inclined. The satellite travels at approximately 7,5km/s and orbits the Earth approximately 14,8 times per day. It is enabling communication with a ground station for maximum period of 13 minute per pass. The mission control facility is situated at Rumpin, Bogor i.e. 6,37 o South and 106,6 o East. Since the control station is located at equator region, this satellite can be accessed at least 3 4 times per day. In order to get complete in-orbit monitoring and maintenance, this condition needs for supported from other ground station. Therefore, two control station are located at Berlin, Germany (52.52 o North and o East) and Spitzberg, Norway (78.20 o North and o East). By using the network within those control stations, all satellite passes can be accessed. After the satellite was separated from the PSLV C7 on January 10 th :12:31.59 UTC, ISRO sent the orbital parameter of LAPAN-TUBSAT when it was injected into its orbit. However, this orbital parameter was out of date after 24 hour. The control station could not use this set of orbital elements for tracking anymore. SUBJECT : POD RESULTS FROM CLG-INS : PSLV-C7 / LAPANTUBSAT MISSION REFERENCE FRAME : Earth Mean Equator and Equinox of J2000 EPOCH : :12: (UTC) Injection Parameters ALTITUDE LOCAL (KM) = LOCAL RADIUS OF EARTH (KM) = VELOCITY (KM/SEC) = FLIGHT PATH ANGLE (DEG) = AZIMUTH INERTIAL (DEG) = GEODETIC LATITUDE (DEG) = EAST LONGITUDE(DEG) = Orbital Elements SEMI-MAJOR AXIS (KM) = ECCENTRICITY = INCLINATION (DEG) = ARGUMENT OF PERIGEE (DEG) = RIGHT ASC. OF ASC. NODE (DEG) = MEAN ANAMOLY (DEG) = State Vector X (KM) = Y (KM) = Z (KM) = XD (KM/SEC) = YD (KM/SEC) = ZD (KM/SEC) = PERIGEE ALTITUDE (KM) = APOGEE ALTITUDE (KM) = Figure 12-1 Orbital Parameter of LAPAN-TUBSAT From ISRO after Separation 62

75 On January 11 th 2007, NORAD published five new flying object that tracked by its radar. Those are the objects that orbited by PSLV C7. LAPAN-TUBSAT should be the lowest one since it was injected to backward during separation maneuver ª U 07001A B U 07001B C U 07001C D U 07001D E U 07001E Figure 12-2 Orbital Elements of New Flying Object by NORAD On January 13th 2007, NORAD has already identified the elements orbit of LAPAN- TUBSAT. LAPAN-TUBSAT U 07001A Figure 12-3 Orbital Elements of LAPAN-TUBSAT by NORAD First acquisition of LAPAN-TUBSAT was done at January 10 th :49 UTC via Spitzberg control station. It was second apparent of LAPAN-TUBSAT from Spitzberg. Since the satellite is launched with empty battery, the control station let the satellite to gather the power using its solar panels before it was commanded. In the first telemetry, the switch register show that everything is zero. It means all of sub system is switch off. The battery is fully charged as the voltage level reach 14,2 V. The temperature around the satellite sides do not differ significantly showing that the satellite is slowly nutating and therefore, no side is expose to the sun for too long. The OBDH telemetry gives information more detail on the satellite status. It shows that the main computer has been activated for 2 hour 53 minutes and all subsystem timer value are still in default. In the LAPAN-TUBSAT power control, there is procedure to limit the duration of power supplying to the devices. It is named power on time. The power on time should be set in the small number to save the power. During early orbit phase, it was set 1800 second. In the default setting of OBDH, it is set to infinities, shown by number of s. 63

76 ## LAPAN SERVER ############################################################## 2007/01/10 06:51:52 PCDH high level command [0xB5 0xAB 0xEE 0x0A 0xFF 0xFF 0xFF 0xFF 0x00 0xEE 0xEE 0xEE 0xEE 0xEE] PCU Telemetry Switch Register : Status Fuse/TTC : System Time : 10424s = 0d 2h 53min 44sec Solar Panel +X : 1.1V 12mA Solar Panel -X : 14.6V 133mA Solar Panel -Y : 14.6V 167mA Solar Panel -Z : 14.7V 894mA Sun Sensor +Y : 1mA Sun Sensor +Z : -0mA Main Power Bus : 14.22V 180mA Voltage 29V/12V/-5V : 26.52V 0.02V -4.99V Current TTC1/TTC2 : 64mA 62mA Current Gyros/Wheels : 14mA 44mA Current Coils/STS : 5mA 12mA Current Stepper+Cam/S-Band: 20mA 22mA Temp PCDH CPU/Housing/DCDC: 13 C 12 C 16 C Temp Battery/Middle Plate : 12.3 C 8.9 C Temp +X/-X : 2.6 C 6.0 C Temp +Y/-Y : 1.1 C 3.0 C Temp +Z/-Z : 2.1 C 4.5 C Temp S-Band : 9.4 C Target Current Coil X/Y/Z : -0mA -0mA -0mA Figure 12-4 Power Control Unit Telemetry of LAPAN-TUBSAT 64

77 ## LAPAN SERVER ############################################################## 2007/01/10 06:52:01 PCDH high level command [0xB5 0xAB 0xEE 0x0A 0xFF 0xFF 0xFF 0xFF 0x10 0xEE 0xEE 0xEE 0xEE 0xEE] OBDH Telemetry Hammer Counter : 0FE0 * 324s = 15d 5h 45min 36sec Reset Counter : 0 Flag Register : System Time : 10434s = 0d 2h 53min 54sec Command Counter : 2 Com Enable : ON Time (remaining power-on time) Wheel X/Y : s (OFF) s (OFF) Wheel Z : s (OFF) Gyro X/Y : s (OFF) s (OFF) Gyro Z : s (OFF) Stepper : s (OFF) Cam 1/2 : s (OFF) s (OFF) S-Band : s (OFF) STS / Coils : s (OFF) s (OFF) Timed Switch ON Time: s Timed Switch ON Reg.: Timed Exec Time : s Timed Exec Address : 0x Event Log Pointer : 0x0047E0A4 Telemetry Pointer : 0x Error Code : 0x08D48000 Error Stack Ptr : 0x Error Address : 0x Status Register : Figure 12-5 First OBDH Telemetry of LAPAN-TUBSAT 65

78 ## LAPAN SERVER ############################################################## 2007/01/10 06:56:47 PCDH high level command [0xB5 0xAB 0xEE 0x0A 0xFF 0xFF 0xFF 0xFF 0x10 0xEE 0xEE 0xEE 0xEE 0xEE] OBDH Telemetry Hammer Counter : 0FDF * 324s = 15d 5h 40min 12sec Reset Counter : 1 Flag Register : System Time : 10719s = 0d 2h 58min 39sec Command Counter : 30 Com Enable : ON Time (remaining power-on time) Wheel X/Y : 1800s (OFF) 1800s (OFF) Wheel Z : 1800s (OFF) Gyro X/Y : 1800s (OFF) 1800s (OFF) Gyro Z : 1800s (OFF) Stepper : 1800s (OFF) Cam 1/2 : 1800s (OFF) 1800s (OFF) S-Band : 1800s (OFF) STS / Coils : 1800s (OFF) 1800s (OFF) Timed Switch ON Time: s Timed Switch ON Reg.: Timed Exec Time : s Timed Exec Address : 0x Event Log Pointer : 0x0047E27C Telemetry Pointer : 0x Error Code : 0x08D48000 Error Stack Ptr : 0x Error Address : 0x Status Register : Figure 12-6 Power On Time Setting in the First Tracking 12.2 CONTROLLING THE ATTITUDE The attitude stabilization of LAPAN-TUBSAT is based on momentum bias method. The angular momentum is maintained in Y axis which is perpendicular to flight direction. The angular momentum is desired to be equivalent with rpm of wheel speed. After separation from launch vehicle, satellite has already had angular momentum about 0.19 Nms or equal with 2079 rpm of wheel. To achieve desired condition, LAPAN-TUBSAT makes coil (magneto-torquer) maneuver on Y axis to raise magnitude of angular momentum and to drive its vector. The angular momentum was established perpendicular to the orbit at January 28 th According to the measurement on January 23 rd 2007, LAPAN-TUBSAT has property of nutation angle about 3 deg when all wheels are switched off. 66

79 Figure 12-7 Gyro Measurements of LAPAN-TUBSAT Figure 12-8 Calculation of Nutation Angle (θ) from Gyro Measurements 67

80 The angular momentum has to be maintained perpendicular to the orbit. Drifting of its vector will cause shifting on camera pointing. The drifting on angular momentum vector will be seen while the satellite is rotating and cutting horizon. The maintenance of angular momentum is done using the coil in Y axis. Figure 12-9 Flat Horizon Indicate the Angular Momentum Perpendicular to the Orbit Figure Captured Horizons of Drifting Angular Momentum 12.3 PAYLOAD DATA RECEIVING First video of LAPAN-TUBSAT was taking on January 12 th At the first capturing, the blue channel of the high resolution camera has been saturated. It gives result of blue image. The camera is initially set to operate in full auto modes, meaning that the gain, white balance and shutter speed will be adjusted automatically by the camera to achieve optimum pictures.. However, this full auto mode does not work every time. Manual setting of the camera has to be done to solve the problem, such as to remove the blue tinge from the images of the high resolution camera. 68

81 Figure Saturated Blue Channel on High Resolution Camera Figure High Resolution Camera Image after Adjustment Hundreds of images have been captured by LAPAN-TUBSAT ever since. Some of them can be seen on the figures below. 69

82 Figure 13 Changi Airport of Singapore, April 22 nd

83 71 Figure Merapi Volcano, Central Java, May 24 th 2007.

84 Senayan Monas Cengkareng Airport Tanjung Priok Figure Jakarta, July 12 th 2007 With its ability to perform cross-track maneuver (pitch and roll), LAPAN- TUBSAT is able to widen its swath significantly, in figure above for example, demonstrate that the swath for high resolution camera can be extended to more than 20 km, to observe all necessary objects in Jakarta in one pass. 72