Reconnaissance Payloads for Responsive Space

Transcription

1 4th Responsive Space Conference RS Reconnaissance Payloads for Responsive Space Stanley Kishner, David Flynn, Charles Cox Goodrich Optical and Space Systems Division Danbury, CT 4th Responsive Space Conference April 24 27, 2006 Los Angeles, CA

2 AIAA-RS RECONNAISSANCE PAYLOADS FOR RESPONSIVE SPACE Stanley Kishner, David Flynn and Charles Cox Goodrich Optical and Space Systems Division, Danbury, CT Abstract A key mission fueling the interest in Operationally Responsive Space (ORS) is optical reconnaissance. Minimizing the cost and delivery schedules of optical reconnaissance payloads having true operational capability will be key to the success of these missions. Modification of existing proven airborne reconnaissance payloads provides a practical path for achieving this Responsive Space capability. In addition to space-based sensors such as the Multispectral Thermal Imager (MTI) developed for Sandia National Laboratories and launched in early 2000 and optical assemblies for the recently launched Japanese ALOS satellite, Goodrich currently provides a range of imaging sensor systems and services for airborne reconnaissance. Goodrich has provided the reconnaissance cameras for the U-2 since 1957, with the current Senior Year Electro-Optical Reconnaissance System (SYERS) electrooptical system providing a robust set of outputs supporting IMINT and MASINT missions. The capabilities of the SYERS system have continually improved through our P 3 I program. From a low earth orbit of 300 kilometers, a SYERS system modified for use in space provides a ground sample distance of approximately 1-meter. It is this system and its functional elements that form the basis for our Responsive Space Reconnaissance (RSR) approach. The Goodrich approach for producing payloads for RSR, as originally described at the 3rd Responsive Space Conference [Cox, 2005], can be visualized as pulling from our product stream of airborne sensors to build an inventory of RSR payloads that can be made available upon short notice. The major effort for adapting the SYERS sensor system for responsive space is associated with the focal plane and electronics. This adaptation can be accomplished with parts and processes compatible with a short duration space mission and aimed at reducing the power consumption for compatibility with a low-cost spacecraft bus. Our vision for RSR Payloads is to establish a pre-positioned, rapid-response process that can adapt our continually evolving product line of high acuity airborne sensors for responsive space missions as the need for such missions is identified. In this paper we describe the SYERS sensor, its modification for use in space and interfaces to candidate spacecraft. We also address the CONOPS that allow a modified SYERS sensor to meet responsive space needs. In summary, optical imaging payloads for RSR can be evolved from our operationallyproven line of tactical and strategic airborne sensors, which have demonstrated ondemand support to our warfighters. These existing airborne systems emphasize operational availability and can be readily adapted for RSR missions. This philosophy and capability is directly aligned with ORS needs. Introduction Goodrich has identified a transformational approach for RSR payloads supporting ORS objectives. This approach leverages US Copyright 2006 by Goodrich Corporation. Published by AIAA 4 th Responsive Space Conference 2006 with permission. 1

3 Government investments in high quality Airborne Reconnaissance systems by modifying Goodrich s current airborne operational systems to provide reconnaissance capabilities from space to support the ORS vision. In this paper we describe these systems, summarize the utility provided by them, and describe the hardware modifications of the U-2 SYERS electro-optical sensor and corresponding operational scenarios that make the resulting sensors consistent with low-cost space mission requirements. The Goodrich approach has several distinct advantages: Minimizes non-recurring costs and risk by leveraging existing designs of airborne assets that are currently in production Provides a low-cost, capabilitiesbased solution, which avoids the cost and burden of traditional top-down procurements. The low recurring cost and schedule required for RSR can been achieved for the airborne payload using existing processes, facilities, and trained personnel Leverages government investments in launch vehicle/bus/ground station assets by providing compatibility with the JWS-D2 Spacecraft Bus and ORS Command and Tasking Protocols, and providing data processing and storage based on JWS-D1 hardware. Future growth of our RSR approach leverages upgrades in airborne assets (e.g., better resolution, more sensitivity) Our approach incorporates a new, lower cost method of fabricating multispectral TDI Focal Planes that provides tighter spectral band registration. Overview of Goodrich Reconnaissance Products Goodrich Optical and Space Systems Division (OSSD) is a pioneer in modern reconnaissance. Our heritage over the last 50 years began with the design and manufacture of the cameras for the world s first space-based photo-reconnaissance satellite, CORONA. This legacy of Goodrich success in space continues to the present, with examples including the Multispectral Thermal Imager, the x-ray telescope used on NASA s Chandra Observatory, star trackers, the optical systems on the recently launched Japanese ALOS Reconnaissance Satellite, and other complex space payloads. We continue to excel in the development of special purpose EO payloads and subsystems for demanding space applications. As a leader in airborne reconnaissance, Goodrich EO sensors have provided strategic intelligence collection on the U-2 platform since its inception. The Goodrich SYERS-2, a state-of-the-art multispectral sensor, is the Air Force s most advanced real-time long-range EO sensor. We have continually provided enhanced capabilities through successive generations of SYERS sensors. The current version of the Goodrich operational sensor developed for use in the U-2 is the SYERS-2 sensor shown in Figure 1. This multi-spectral sensor system has seven imaging channels, allowing daytime and nighttime intelligence gathering. The SYERS sensor mounts internal to the U-2 aircraft via mechanical, electrical, and data interfaces supporting interchangeability with the Synthetic Aperture Radar sensor system. 2

4 Figure 1. The SYERS-2 Sensor System Integrates Internal to the U-2 Nose. The Goodrich SYERS-2 sensor combines the information from 3 spectral bands into one color image. It currently has three baseline MSI products: All Visible Composite (Pan, Red, Green) All Infrared Composite (MWIR, SWIR1, SWIR2) Mixed Channel Composite (SWIR, Green, Pan) These bands support various intelligence tasks, such as discrimination of man-made from natural materials, camouflage identification and detection, identification of active vehicles and aircraft due to their increased thermal signature, moving Target Indication (EO-MTI), and water penetration. The SYERS-2 sensor has a two-axis gimbal providing precision pointing along-track and cross-track for target selection in search, pinpoint targeting, tracking, and stereo imaging modes. From its typical altitude, it produces images better than NIIRS-7 at Nadir. Goodrich has provided over fifty years of continuous support and service to the U-2, as illustrated in Figure 2. The approach of leveraging the Country s on-going investments in high quality Airborne Sensor systems for use as Operationally Responsive space assets takes maximum advantage of this evolutionary improvement in capabilities. Iris II and III OBC pan SYERS SYERS-2 Research OBC apochromatic pan LSRA EO LOROP pan Figure 2. Interim EO OBC apochromatic pan Delta pan Senior Chevron Goodrich has Provided Continually Evolved Sensor Capabilities to the U-2 for Over 50 Years. 3

5 Goodrich developed the DB-110 sensor as a derivative of SYERS. With a smaller aperture than SYERS, this lightweight sensor is designed for use on tactical aircraft, and is offered in a pod-mounted configuration. This sensor system, shown in Figure 3, has been flying since 1997 and consists of a 2-axis gimbaled sensor, stabilized in pitch and roll, providing simultaneous operation in visible and infrared wavelengths. It has long focal length optics for high altitude standoff operation in both visible and IR wavelengths. Figure 3. The DB-110 System Fits Within a Pod Attached to Tactical Fighter Aircraft. Goodrich integrates and delivers a complete reconnaissance system in an aircraft pod that attaches to tactical fighter aircraft via standard structural, electrical and data interfaces. In addition to the DB-110 sensor itself, this Goodrich pod system includes the sensor electronics, data recorder, data link, power distribution and environmental control system and a Reconnaissance Management System (RMS) that controls all operations of the podded equipment. The RMS is configured to operate with MIL- STD 1553B and MIL-STD 1760 interfaces. The Goodrich reconnaissance pod comprises all the structural, electrical, and communications functions of a space-based payload. Goodrich also provides a mobile ground station with capability for image processing and exploitation. The DB-110 reconnaissance system was developed by Goodrich using internal funds and has been successful in capturing a large share of the highly competitive International market. The DB-110 was designed to balance capabilities and cost, and the Goodrich ORS payload leverages the lessons learned in developing this successful best value system. The Goodrich Approach to Responsive Space Operationally responsive Electro-Optical (EO) imaging capability exists today and is routinely used to provide intelligence information to the tactical warfighter. This capability is provided by Goodrich Reconnaissance systems having plug and play interfaces to strategic (i.e., U-2) and tactical airborne platforms. These operational systems have visible, IR and multispectral capability, and the resulting data products readily interface into an existing infrastructure providing timely information to theater commanders. The ORS vision is to provide the local Theater Commander direct control over a range of assets that can provide capabilities that complement those of existing ground, sea, airborne, and space-based systems. These systems can be interconnected into a flexible architecture that will allow these assets to operate more effectively in a tactical environment. An ORS EO payload provides the Theater Commander with direct dedicated tasking, timely dissemination of tactically significant imagery, and frequent non-provocative access to the entire theater. The data provided by an RSR EO payload can be used to cue other theater assets to provide additional data, or to take direct action. We have developed a concept for a comprehensive E-O payload based on our SYERS-2 Sensor system technologies. 4

6 Table 1 summarizes the makeup of the payload. Table 1 Features of RSR EO Payload Based on SYERS-2 Sensor SYERS-2 Airborne Sensor with Upgraded TDI Focal Plane 0.42-meter aperture telescope (glass/graphite construction) Wide field-of-view: > 2 (>10.9 km swath width from 300 km orbit) High signal-to-noise ratio (>10X IKONOS) High resolution (1-meter GSD from 300 km orbit) NIIRS 4 High area coverage (58.2 sq km/sec at NIIRS 4) Multispectral sensing (3 bands) Solid State Data Processing and Storage Unit (DPSU) Payload primary control Common Data Link (CDL) interface Spacecraft Command & Control Interface (compatible w/ors Modular bus) Solid state buffer (6000 sq km of uncompressed NIIRS 4 pan imagery) Image compression and file formatting (compression commandable to 16:1) Spacecraft power regulation Payload to Spacecraft Bus Mounting Structure and Interface Thermal Control System Allowing Operation in All Low Earth Orbits Aperture Door Protects Payload from Contamination The Goodrich RSR payload, located in a 300 km orbit, will provide high quality (NIIRS 4) imagery, with about 1 meter ground sample distance (GSD) at nadir, over a wide swath width of 10.9 km. In this orbit the payload provides a high image collection capacity (> 58.2 square kilometers per second at full resolution) comparable to IKONOS. The Goodrich RSR payload can also be used in higher orbits, providing increased collection capacity with reduced image quality. In higher orbits the GSD will increase linearly with the altitude and the collection capacity will increase with the square of the altitude. A high sensitivity PAN channel provides greater than 10 times the signal on a pixel as IKONOS allowing image collection to be performed under the challenging illumination conditions required for tactical reconnaissance. The PAN channel supports a bidirectional readout allowing the payload to perform single pass stereo image collection similar to IKONOS. The payload also has two multispectral bands (Green and Red) with spectral bandwidths optimized for military utility. The Goodrich RSR payload is based on components that were specifically designed for mission critical military remote sensing applications. The two key components of a remote sensor are the optical system and the focal plane. The optical system uses a thermally stable, lightweight, glass/graphite telescope with a large 0.4 meter diameter aperture that has been proven on the U-2 SYERS-2 sensor. The SYERS-2 optical system will require a minor modification to the focal plane interface to allow the use of Goodrich s latest generation multispectral visible focal plane. The onboard processing and data storage electronics will leverage components that were developed for use on the JWS-D1 (Roadrunner) program. The Goodrich RSR payload is designed to be compatible with the Operationally Responsive Space Modular Bus (ORSMB) that is currently being developed by AFRL. Figures 4 and 5 show the Goodrich ORS payload integrated with a notional ORS modular bus in multiple configurations: enclosed in a Falcon fairing, with the fairing removed, and in the operational configuration. 5

7 Falcon Payload Fairing Dynamic Envelope Thermal Shroud (Aluminum) Aperture Door, One Shot, Captive (Aluminum) Strawman Bus (0.8 x 0.8 x 0.6 meters) Payload Separation Adapter (Aluminum) Separation Plane RSR Payload in Falcon Fairing RSR Payload on ORS Modular Bus Figure 4. Goodrich RSR Payload fits Within Falcon Fairing with Ample Margin. SYERS-2 Camera Flight-Proven, High Resolution Aperture Door (Deployed) Protects Payload During Storage, AI&T and Launch Thermal and Contamination Control Shroud Allows Operation in all LEO Orbits Payload Support Structure Provides a Modular Interface Data Processing and Storage Unit Provides an Interface Compatible with JWS-D1 Strawman Bus Strawman High-Gain Antenna Notional Payload Separation Adapter Strawman Solar Arrays (Deployed) Figure 5. Goodrich RSR Payload in Operational Configuration. 6

8 Goodrich RSR Payload Optical Multispectral System Focal Plane Focus Control Image Compression Focal Plane Electronics Instrument Controller DPSU Shroud Heater & Aperture Door Control Solid State Buffer (SSB) SPA-U Interface Spacecraft Bus Figure 6. Goodrich RSR Payload Functional Block Diagram. A functional block diagram of the Goodrich RSR payload is shown in Figure 6. The optical system images the scene onto the three spectral channels (PAN, Green, and Red) of the focal plane. The image data for each band is then digitized to 12 bits and sent to the focal plane electronics for data formatting and preconditioning prior to data compression. The formatted data is sent to the data compressor where a compression algorithm is selectively commanded to provide variable levels of data compression. The data is then sent to an on-board solid state buffer. An Instrument Controller is present to parse commands to and from the sensor payload through an ORS modular bus compatible SPA-U plug and play interface. All commands and housekeeping data on the payload are conveyed to and from the payload via this interface. A dedicated high speed interface from the solid state buffer to the communications downlink is also provided. The image compression provided by the Goodrich RSR payload is compatible with the Multi-Band Integrated Satellite Terminal (MIST) followed by a MIST Interface Module (MIM) containing a data recorder to receive the down loaded imagery. The MIM provides for interfacing the MIST to the Remote Tasking Terminal (RTT) which would process the imagery similar to the JWS-D1 experiment. The RTT provides for the conversion of the JPEG compressed files into JPEG-2000 image files for display on the RTT, and into National Imagery Transmission Format (NITF 2.1) files suitable for transfer via CD or DVD to a Tactical Exploitation System Lite (TES- Lite) workstation for intelligence processing and dissemination. It is assumed that minor software modifications would be required for the command and control of the Goodrich payload from the RTT. Modification for Space Goodrich has been engaged for decades in the development and production of high quality space-based EO sensors for a wide variety of applications. These include star trackers, earth sensors, and ultraviolet, visible and infrared telescopes. A recent example of one of Goodrich OSSD s custom-developed Space payloads is the Multispectral Thermal Imaging System (MTI) launched in early 2000, pictured in Figures 7 and 8. Another example of Goodrich technology and infrastructure for space-based EO systems is our product line for high quality star trackers and attitude sensors. Goodrich has provided over 90 star trackers, with 33 7

9 units currently operational on-orbit, each one consisting of an optical system, a stable opto-mechanical structure, a thermoelectrically cooled focal plane, electronics, and software. This product line, developed under internal funding, has successfully captured a large share of the competitive star tracker market, a market that requires the delivery of firm fixed price hardware to challenging schedule requirements. Examples of Goodrich star trackers are shown in Figure 9. The technologies and capabilities that are currently used to develop, build, qualify, and deliver our space-based payloads can be applied to our airborne sensor line to achieve the Responsive Space Surveillance objective. Figure 7. The MTI Satellite Provides Detailed Multi-spectral Images of Ground Targets. Figure 8. Goodrich Developed and Delivered the MTI Payload. Figure 9. Goodrich Star Trackers are Used on a Variety of Spacecraft. 8

10 The main adaptation required to the SYERS- 2 sensor system for responsive space is associated with the electronics. The functionality and architecture must be implemented with parts and processes compatible with the space environment. Operation in the vacuum of space influences the means by which the electronics are cooled, and the choice of non-outgassing materials. Exposure to radiation in space is also a concern and parts with known radiation susceptibility must be avoided. Additionally, the modified design must provide power consumption compatible with a low-cost spacecraft bus. We estimate an orbital average power of less than 200 watts for a modified SYERS-2 sensor. The Goodrich RSR payload has been designed to be used in a strap-down configuration on an agile spacecraft; therefore the self-contained pointing and stabilization capability of the airborne sensors is eliminated reducing cost, weight, and power. Interface Compatibility A number of enabling technologies that are required to achieve the ORS vision are currently being developed. The Goodrich RSR payload is designed to be compatible with these technologies. The Goodrich RSR payload interface characteristics, as shown in Table 2, are compatible with the preliminary interface requirements for Operationally Responsive Space Modular Bus (ORSMB) being developed by AFRL for the JWS-D2 program. Table 2 Interface Compatibility Interface Type Mass Properties Envelope Pointing Knowledge Agility and Stability Power Payload Processing and Data Storage Thermal Payload Data Downlink Goodrich RSR Payload Mass < 150 kg C.G. = 0.6 meters from Bus I/F Ample margin within FALCON fairing dynamic envelope Payload field mapping error to within 1 pixel (3.4 µrad) RMS will not drive geolocation accuracy Full Resolution (1 m GSD) scan rates: 1 st pass: 0.2 to 1.2 deg/sec 2 nd pass: 1.2 to 2.2 deg/sec 2x2 Binning (2 m GSD) scan rates: 1 st pass scan: -0.8 to 1.2 deg/sec 2 nd pass scan: 1.2 to 3.2 deg/sec 2 scans required for single orbit stereo. Pointing Jitter < 1 µrad <250 Watts 28 VDC <200 Watts orbital average power for 10 minutes operation per orbit Payload processor provides a plug and play interface and controls all payload functions. Solid State Data Buffer (64 Gbits) can store up to 6000 square kilometers of uncompressed full resolution PAN imagery. Electronics dissipate <75 Watts to S/C. Payload incorporates a Thermal Control System to radiate heat and provide thermal control allowing operation in all LEO orbits CDL interface compatible with JWS-D1 9

11 Image Quality The SYERS-2 airborne sensor on which the Goodrich RSR payload is based is capable of providing imagery with a NIIRS rating greater than 7 from the U-2 [Leachtenauer, 1997 and Maver, 1995]. The Goodrich RSR payload is capable of providing tactically significant image data (NIIRS 4) from a 300 km orbit, which is comparable to the image quality provided by the IKONOS commercial remote sensing satellite (NIIRS 4.5). A system with a NIIRS rating of 4 or higher can provide a theater Commander with data products that can be effectively used for target acquisition, identification, and that can be used to cue other theater assets. For an RSR system it is questionable if a NIIRS rating higher than 5 justifies the additional cost given the capabilities of other theater assets to provide high quality imagery. Figure 10 shows a sample of imagery from a Goodrich airborne sensor that has been numerically degraded to simulate a NIIRS rating comparable to the Goodrich RSR payload in a 300 km orbit. Image quality is a strong function of the ground sample distance (GSD), which is the projection of a detector pixel on the ground. The GSD in Figure 10 is 1 meter. Image quality is also a function of the signal-tonoise ratio of the sensor. The Goodrich RSR payload has a high throughput optical system and a high sensitivity detector that provides 10 times the signal on a pixel as IKONOS. This allows the collection of imagery in the challenging illumination conditions required for tactical reconnaissance. Unclassified Crown Copyright/MOD The Goodrich RSR Payload Provides NIIRS 4 Imagery from a 300 km Orbit Figure 10. A Sample Scene with Image Quality Comparable to the Goodrich RSR Payload in a 300 km Orbit. 10

12 The previous discussion on image quality focused on the utility of high resolution panchromatic (PAN) imagery. The ability to simultaneously collect image data from multiple spectral bands has proven to be useful in a number of applications. For example, spectral data can be used to acquire partially hidden or camouflaged targets and to identify targets and materials. The effectiveness of spectral data is very application specific; a few well placed spectral bands can perform better than many narrow spectral bands in some applications. Spectral bands that are useful for mapping natural resources may not be useful for discriminating between natural and manmade objects. Many operational airborne sensors and commercial remote sensing satellites have a multispectral (MS) capability. For example the IKONOS and Quickbird commercial remote sensing satellites have four MS bands (Blue, Green, Red, and Near IR) in addition to a PAN band. The Goodrich RSR payload retains the 3 visible spectral bands (PAN, Green, and Red) from the SYERS-2 payload with spectral bandwidths optimized for military utility. The Goodrich RSR payload can be modified in the future to include additional visible or IR spectral bands (which are already fielded in the SYERS-2 sensor) if required. Other theater assets also have the capability to provide multispectral, or hyperspectral, imagery so a more cost effective solution may be to use the Goodrich RSR payload to cue these assets if additional spectral data is required. Concept of Operation (CONOPS) Overview The Goodrich RSR payload is derived from proven airborne systems that provide data products currently used by theater commanders to make real-time decisions. Our approach provides the tactical theater Commander with EO intelligence from space using assets proven in airborne operations, and using the existing command and control infrastructure. Figure 11 shows an example of the ORS sensor ground track for a 300 km circular orbit, and the corresponding field-of-regard (FOR) and instantaneous field-of-view (IFOV) of the sensor. The Goodrich RSR payload provides Intelligence, Surveillance and Reconnaissance (ISR) capabilities that augment and complement those of other theater assets (space, near-space and airborne). Table 3 compares the capabilities of the Goodrich RSR payload to airborne/near-space assets and commercial remote sensing satellites. 11

13 Figure 11. The Goodrich RSR Payload Provides the Theater Commander with Non- Provocative Access to the Entire Theater with Multiple Revisits Each Day. Capability Non-Provocative Access to Denied Areas Short Term Continuous Persistence Over Limited Areas Long Term Periodic Persistence Over The Entire Theater Image Collection Capacity Image Quality Near Real Time Tasking and Data Dissemination Call Up to Theater Tasking Table 3 Summary of ISR Capabilities of Theater Assets Airborne and Near Space Assets Limited penetration at borders with cooperative host nations UAVs can loiter over limited areas for up to 24 hours. Near-Space airships can loiter for longer periods The revisit rate over entire theater limited by low collection capacity and vehicle rates Low < 1 km 2 /second Limited by vehicle rate High NIIRS: SYERS > 7 Global Hawk > 6 Direct control by the theater Commander. Near real time tasking within small field of regard. Near real-time data download via CDL. Days if the support infrastructure (e.g. airfields) is in place. Requires cooperation of a host nation Commercial Remote Sensing Satellites Unlimited No short term loiter capability The average revisit rate for a commercial remote sensing satellites is 1 to 3 days High IKONOS > 58.6 km 2 /second Moderate meter GSD NIIRS: IKONOS 4.5 Assets support multiple users and are not under the direct control of the theater Commander. It takes years to build and launch new systems Goodrich RSR Payload Unlimited No short term loiter capability A single ORS satellite can provide multiple revisits per day. 3 to 4 ORS satellites can provide 90 minute revisit rates continuously. High > 58.2 km 2 /second Moderate 1-meter GSD NIIRS 4 Direct control by the theater Commander. Near real time tasking within a wide field of regard during an overpass. Near real-time data download via CDL. ORS goal is seven days 12

14 The Goodrich RSR payload provides a combination of capabilities that cannot be matched by airborne or commercial space assets alone. It augments the ISR capabilities currently available to the theater Commander, especially during the critical periods of theater build-up and theater operations. It also has the capability to collect timely imagery over the entire theater. The data from the Goodrich RSR payload can be used to cue other space, airborne, or ground assets so they can be used more effectively. Table 4 shows an example of the how the capabilities of airborne assets, commercial space assets, and the Goodrich RSR payload can be used together during a theater operation. Stage of Operation Prior to Conflict Conflict Identification Theater Buildup (weeks, months) Theater Operations Prior to Control of Air Space (weeks, months) Theater Operations Once Control of Air Space Achieved (months) Stabilization and Peace Keeping Table 4 Utility of ISR Assets During a Theater Operation Airborne and Near Space Provocative Requires cooperation of a Host Nation Provocative Requires cooperation of a Host Nation Provocative Requires cooperation of a Host Nation Vulnerable to hostile actions Able to loiter Provides high quality imagery over limited areas Unlimited Use Able to loiter Provides high quality imagery over limited areas Provocative Able to loiter Provides high quality imagery over limited areas Commercial Remote Sensing Satellites Data used for long term global intelligence and strategic planning Existing assets can be tasked to identify initial conflict indicators Non-Provocative Provides infrequent ISR data over the entire theater Provides infrequent ISR data over the entire theater No ability to replenish or augment if required Provides infrequent ISR data over the entire theater No ability to replenish or augment if required Non-Provocative Provides infrequent ISR data over the entire theater Goodrich RSR Payload Not Available (High revisit rate and timeliness are not required) Requires 7 days to call up Non-Provocative Provides timely ISR data over the entire theater Can cue other space assets Provides timely ISR data over the entire theater Can cue other space, airborne, or ground assets Rapid replenishment capability if required Provides timely ISR data over the entire theater Can cue other space, airborne, or ground assets Rapid replenishment capability if required Non-Provocative Provides timely ISR data over the entire theater Can cue other space, airborne, or ground assets 13

15 Theater commanders require dedicated command and control, and the timely direct downlink of imagery to make tactical decisions. One of the goals of the ORS concept is to provide the theater Commander with dedicated space-based systems that provide the flexible command/control, and the timeliness of data, currently available from airborne platforms. For example, one of the technologies that is being demonstrated on the JWS-D1 program is the use of a modified tactical Common Data Link (CDL) that provides in-field tactical command, control and communications of the JWS-D1 satellite. The space-based CDL is compatible with the airborne CDL that is currently used to operate UAVs including Global Hawk and Predator. The CDL can provide a high rate downlink of 274 Mbps and an uplink rate of 200 kbps. Figure 12 shows a typical timeline for an overpass of an RSR asset over a theater. From a 300 km orbit there are approximately 8 minutes when the satellite will be above the local horizon. When the satellite is nominally 5 degrees above ground elevation, a condition that is met for about 6.5 minutes during an overpass, the upload of tasking commands via a CDL ground station in theater is possible. Tasking commands, which control the spacecraft attitude slewing and payload data collection, can also be uploaded using the existing space system support infrastructure (e.g. ground stations outside of the theater or from communications satellites). A hemispherical antenna is used to support the low bandwidth upload of commands so slewing the satellite to point toward the ground station is not required during upload. Imaging is performed when the target area is approximately within 30 degrees of nadir. This preserves the design ground resolution, and avoids the deleterious effects of atmospheric haze on image quality. From an altitude of 300 km, this condition is satisfied for about 45 seconds of the orbit for any given target location. Each orbital pass provides several minutes of near-nadir access to a wide-area theater of interest. Opening up the field-of-regard beyond 30 degrees can increase coverage at the cost of lower image quality. By using an agile spacecraft, multiple targets can be collected during an overpass for a region from nadir to ±30 degrees, both along-track and crosstrack. Orbital Period CDL Upload Access Period CDL Download Access Period 6.5 minutes 3.5 min 90.5 minutes CDL Command Upload Pointing Sequence Imaging Sequence CDL Image Download Figure 12. Goodrich RSR Payload Field Tasking via CDL. 14

16 When the satellite is nominally 15 degrees above ground elevation, a condition that is met for about 3.5 minutes during an overpass, the high bandwidth download of image data via the CDL to a ground station in theater is possible. During high bandwidth download the satellite must slew to point the high gain antenna at the ground station. The Goodrich ORS payload will include a solid state data recorder that will have the capacity to store 6000 square kilometers of high resolution panchromatic image data. The download of image data can also be performed using the existing space system support infrastructure (e.g. download to ground stations outside of the theater or to communications satellites). The ability to upload tasking commands within minutes of an overpass, and to provide decision quality image data to the field in near-real time, allows the theater Commander to effectively act on the data. For example, imagery from the Goodrich RSR payload can be used to cue space, airborne, or ground assets to collect higher resolution imagery of a target or to take offensive action, before the target has time to take evasive action. In this example the Goodrich RSR payload acts as a force multiplier, increasing the effectiveness of available theater assets. Coverage/Revisit Time The coverage of a desired theater can be optimized by choice of orbit parameters and the number of sensors/spacecraft for an ORS mission. The orbits selected for ORS missions may be significantly different than those used by legacy space assets, e.g. commercial remote sensing satellites such as IKONOS, where the orbital parameters are optimized for global coverage with infrequent revisits. For example all the current commercial remote sensing satellites (e.g. IKONOS, ORBVIEW, and Quickbird) are in high inclination Sun synchronous orbits that on the average revisit a target area once every 1 to 3 days. By selecting a low Earth orbit (LEO) Repeat Coverage Orbit [Wertz, 2005] with an inclination a few degrees above the latitude of the target area, an ORS satellite can provide 4 to 5 overpasses of a target per day. For some proposed ORS missions, multiple ORS spacecraft may be used to further improve coverage. For example, 3 or 4 ORS satellites can provide 90 minute revisits over a target continuously. The Goodrich RSR Payload can provide high resolution imagery within 30 degrees of the nadir ground track. From a 300 km orbit a 346-km-wide field of regard is accessible as the spacecraft passes over the target area. Imagery can also be collected beyond 30 degrees field of regard; however the image quality will degrade as the slant range increases. The GSD will increase as a function of the off-track range and will limit the useful field of regard for an airborne platform. In addition to the increase in GSD, a low altitude airborne sensor with a large slant range must stare through a longer atmospheric path than a space-based platform. ISR from space avoids the issue of long atmospheric paths allowing a large field of regard. The Goodrich RSR payload can scan out swaths that are greater than 10.9 km wide for orbits greater than 300 km. The length of the image swath is a function of the time spent collecting data for a particular target. During the available imaging time, multiple swaths can be collected at various alongtrack and cross-track locations. The maximum collection capacity at full resolution, assuming no time for re-pointing is 58.2 square kilometers per second. This is comparable to IKONOS which provides a maximum collection capacity of 58.6 square kilometers per second at full resolution. The Goodrich RSR payload is also capable of providing twice the collection capacity, up 15

17 to square kilometers per second, with a lower resolution (2 meter GSD) on command. Collection efficiency is driven by the agility of the spacecraft, the separation between the desired target areas, and the required signal to noise ratio (SNR). In a remote sensing application there is a tradeoff between the SNR of the imagery and the collection capacity of the sensor. By reducing the scan rate we can increase the effective integration period and increase the SNR, but the collection capacity will decrease. The Goodrich RSR payload provides a high SNR image, allowing a high collection capacity in challenging illumination conditions. Considering re-pointing, we would expect to collect less than 1250 square kilometers of full resolution imagery during an overpass. The Goodrich RSR payload incorporates a Solid State Buffer with a memory capacity of 64 Gbits. It can store up over 6000 square kilometers, 4.8 overpasses, of full resolution imagery with a 12 bit dynamic range, without data compression. The Goodrich RSR payload also features data compression with compression ratios up to 16:1. Downloading to a ground station in the theater via the CDL of a typical overpass, 1250 square kilometers of uncompressed full resolution imagery with a 12 bit dynamic range can be transmitted in under a minute. Summary Existing high acuity airborne reconnaissance sensor designs and manufacturing infrastructure can be leveraged to deliver low-cost space reconnaissance sensors that meet the needs of Responsive Space. Modification of existing Goodrich sensors for use in space preserves their legacy of quality and reliability while minimizing the need for investment in new designs, tooling and facilities. Extra program costs stemming from establishing, flowing and monitoring top-driven requirements are eliminated. References C. Cox, et. al, Reconnaissance Payloads for Responsive Space, Paper No. AIAA-RS , presented at 3 rd Responsive Space Conference, Los Angeles, CA, April 26-28, J.C. Leachtenauer, et. al. General Image- Quality Equation: GIQE. Applied Optics 36, pp (1997). L.A. Maver, et. al. Imagery Interpretability Rating Scales, in Digest of Technical Papers: International Symposium of the Society for Information Display (Society for Information Display, Santa Ana, CA, 1995), vol. 26, pp James R. Wertz, Coverage, Responsiveness and Accessibility for Various Responsive Orbits, Paper No. AIAA RS presented at 3rd Responsive Space Conference, Los Angeles, CA, April 26-28,