GATEWAY TO SPACE SPRING 2006 PROPOSAL

Transcription

1 Colorado Space Grant Consortium GATEWAY TO SPACE SPRING 2006 PROPOSAL Magnetic Field Detection Written by: Sheldon Coutinho Stephen Lepke Scott Rogers Aaryn Stanway Christian Yoder March 23, 2006 Revision B

2 Revision Log Revision Description Date A Conceptual Design Review 03/02/2006 B Preliminary Design Review 03/23/2006 Illegal Survivors Page 2 of 14

3 Table of Contents 1 Mission Overview Design Parts Power Camera, Mirrors, and Timing Circuit Two-Channel HOBO Data Logger and Instruments HOBO Pressure Data Logger Heater Satellite Box Drawings Functional Block Diagram Subsystem and Overall System Requirements Two-Channel HOBO Subsystem Pressure HOBO Subsystem Heater Subsystem Imaging Subsystem Management Organizational Chart Schedule Budgets Test Plan and Results Structural Test Temperature Test Camera Test Final Test Expected Results Illegal Survivors Page 3 of 14

4 1 Mission Overview Our team, Illegal Survivors, plans to build a BalloonSat that will be able to determine the change in magnetic field strength as a function of altitude. Our BalloonSat will also return data corresponding to relative humidity and temperature as a function of altitude. We also plan to image the earth and the balloon in one photo. 2 Design Throughout the history of the Gateway to Space course, there has been a very common protocol and design for each of the boxes. They each contain an imaging unit, a HOBO data logger, and a personalized science experiment. These likenesses cause the boxes to be constructed very similarly. In honor of tradition, our satellite will mimic those BalloonSats that have been launched in the past. Therefore, our approach to the design will be fairly straightforward and simple. With a camera and two mirrors, the team plans to image the earth and balloon in the same photo. With a magnetometer interfacing with a two-channel HOBO data logger, the team plans to measure the change in the magnetic field related to an increase in altitude. A pressure HOBO will be used to measure the pressure in order to determine the altitude of the satellite. A humidity sensor and internal and external temperature sensors interfacing with the two-channel HOBO data logger will allow us to relate temperature and humidity to altitude. 2.1 Parts In order to complete the flight mission, many hardware components will be required to operate the internal functions of the BalloonSat. Below is a list of the necessary items, as well as a description of their individual functions and their roles in supporting the other hardware items Power There will be five sources of power for this experiment. One is a parallel link of three 9-volt batteries that will power the heater. These 9-volt batteries are large, and have enough energy and wattage to power the heater for the two to three hours that the satellite is in flight. The second power source is a link of three 12-volt batteries that will power the timing circuit for the camera. This circuit will be described in Section , but it draws an intermittent amount of power that is dependent on how often the camera takes picture. The third and fourth power sources are the internal batteries inside each of the HOBO units (the twochannel HOBO and the pressure HOBO). They power the HOBOs and the two-channel HOBO s internal and external instruments. The fifth power source is an internal battery inside the camera. It powers the rolling of the film and the opening of the shutter Camera, Mirrors, and Timing Circuit One requirement for the balloon satellite is to have a working camera located in the box to capture pictures of the horizon during ascent. The camera that will be using is already wired to interface with a timing circuit. We will build the timing circuit in class. The timing circuit will activate the camera to take images during the flight. The hole for the camera to take photos was described in Section However, the group is proposing to image both Illegal Survivors Page 4 of 14

5 the ground and the balloon in the same photo. We will be able to accomplish this task very easily by using mirrors. We will install two mirrors outside the satellite. We will position the edges of both mirrors across the center of the hole and the mirrors will be on a With this accomplished it will look like the mirrors have formed the letter V with the bottom of the V touching the edge of the box. This will allow us to take a picture of the ground and the balloon Camera The camera is a Canon Elph Lt that uses 24 mm Advantix film. It has previously been modified to receive signals from the timing circuit. This modification will allow the camera to take pictures without the presence of a human. The camera also has an auto focus mechanism that will need to be considered when the camera is tested with the mirrors. During our flight we will use 40 exposure film Timing Circuit The timing circuit is a series of potentiometers and timer chips with a magnetic relay. The timing circuit will allow a preset time interval to occur between the signals sent to the camera to take pictures. Essentially, a picture may be taken once every second, minute, or hour, etc. depending on the position of the potentiometers Two-Channel HOBO Data Logger and Instruments During the satellite s flight a large amount of data will be gathered through the various conditions. To do this we will use a two-channel HOBO. The two-channel HOBO is a data collection device that can receive and record voltage. The two-channel HOBO will allow us to obtain the internal temperature and humidity readings throughout the trip. With the attachment of various instruments, we will also use the two-channel HOBO to record external temperature and the data from our magnetometer as a part of our scientific experiment Humidity Sensor The two-channel HOBO is pre-equipped with a humidity sensor. We will program the two-channel HOBO to record readings from the humidity sensor every 15 seconds Temperature Sensors We will be monitoring the temperature both inside and outside the satellite box with a two-channel HOBO stored inside the satellite. The two-channel HOBO is equipped with an internal temperature sensor that will measure the temperature inside the satellite. It is also equipped with ports for other instruments. Into one of these ports we will attach an external temperature probe. This temperature probe will be inserted through a hole in the box so it can generate an accurate reading of the outside temperature. In order to get a seemingly continuous feed of temperature date, the two-channel HOBO will consistently monitor both the internal and external temperature every second, and record the data Magnetometer The KMZ51 magnetometer by Philips will be used for our science experiment. It is a small chip that detects variations in the surrounding magnetic field, and outputs different Illegal Survivors Page 5 of 14

6 voltages according to the strength of the magnetic field. The voltage range of the magnetometer is within the milli-volt range. As the maximum voltage input for the twochannel HOBO is 2.5 volts, the magnetometer will be easily compatible with the requirements of the hobo. Fabricating a system that will interface the magnetometer with the HOBO will be slightly more complicated than simply plugging the magnetometer into the hobo. It will be necessary to construct a small circuit board containing the magnetometer, several resistors, a 5 volt power source, and a few other components. Once this circuit is complete, it will then be able to be attached to the HOBO as an entire system. More information about the magnetometer being used can be found at: HOBO Pressure Data Logger The pressure HOBO will be used to measure the pressure during the flight. We will set the data logger to record the pressure every minute. These readings will be converted to altitude. This data will allow us to plot magnetic field strength as a function of altitude. The altitude data will also be used to find ascent and descent rates Heater Throughout the satellite s ascent to approximately 30,480 meters, it will encounter extreme cold. These harsh conditions could harm or ruin our electronic devices that we have installed inside the satellite. We will remedy this problem by installing a small heater to keep the temperature above 15 0 C for the majority of the flight. The heater that we are planning to build is very simple and contains only three 4Ω resistors, a circuit board, and three 9-volt batteries. The three resistors will be placed on the circuit board and soldered together in series to create one 12Ω resistor which will generate enough heat to keep the inside of the satellite warm enough not to damage the electronic devices. The heater will be powered by three 9-volt batteries that will be connected to the heater by wiring all of the positive leads to one end of the heater and all of the negative leads to the other end of the heater. The batteries will provide power to the heater for the entirety of the flight. The heater is required to keep all of the other pieces of hardware in working order. If the internal box temperature falls below 0 C, the circuits and delicate computers onboard may not function properly, which could potentially lead to mission failure. The heater is simply a series of ceramic-like resistors included in a circuit of three 9-volt batteries. In accordance with the law of conservation of energy, because the resistors block so much current, they output energy in the form of heat. This heat will be enough to keep the inside of the balloon-sat at a safe operating temperature for the duration of the mission Satellite Box The box will be roughly in a 16cm x 11cm x 14cm cube made out of foam core. The box will be assembled using epoxy. The inside of the box will be coated with foam for insulation. The outside of the box will be coated with aluminum duct tape for structural support. There will be an aluminum axle that is 12 centimeters in length installed through the approximate center of the box. The aluminum axle will be hollow and one centimeter in diameter. The string from the balloon will be put through the aluminum axle and a knot will Illegal Survivors Page 6 of 14

7 be tied in the string on each end of the axle to hold our BalloonSat in place. There will be a two-centimeter diameter hole on one side of the box to accommodate the camera lens. The mirrors used to take the image the ground and the balloon will be installed beyond the hole on the outside of the box. There will also be a small hole to accommodate the external temperature sensor for the two-channel HOBO. 2.2 Drawings The following is a diagram of our satellite box. The only thing not drawn to scale is the exterior casing. It is two centimeters wide. This is because one centimeter accounts for the foam insulation (not shown in diagram) and one centimeter accounts for the thickness of the foam core. Illegal Survivors Page 7 of 14

8 2.3 Functional Block Diagram 2.4 Subsystem and Overall System Requirements As denoted by the diagram in the previous section, there are four subsystems contained in our BalloonSat: the two-channel HOBO subsystem, the pressure HOBO subsystem, the heater subsystem, and the imaging subsystem. As shown in later sections, our box will be less than 750 grams in mass and we will not exceed our monetary budget of $ Two-Channel HOBO Subsystem The two-channel HOBO contains an internal power source. The two-channel HOBO subsystem records data from its internal instruments: the internal temperature sensor and the humidity sensor. The first channel will record data from the external temperature sensor. The second channel will store the voltage output from the magnetometer. We will convert the voltage readings to magnetic field strength. This subsystem gives us the required data corresponding to internal and external temperatures and relative humidity. It also assists in gathering data for our required science experiment Pressure HOBO Subsystem The pressure HOBO contains an internal power source. This HOBO will record the barometric pressure at certain time intervals during the flight. We will later convert the barometric pressure readings to altitude. This subsystem will allow us to find altitude as a function of time and will allow us to determine the corresponding altitude for each reading in the previous section as well as ascent and descent rates. Illegal Survivors Page 8 of 14

9 2.4.3 Heater Subsystem The heater s power source consists of three 9-Volt batteries. This creates enough power to run the heater for the whole of the flight. The power switch for the heater subsystem will be located on the outside of the box so we can easily activate it on launch day. This subsystem will keep the inside of our box above 0 C during the flight Imaging Subsystem The camera contains an internal power source. The timing circuit s power source consists of three 12-Volt batteries. This creates enough power to run the timing circuit for the whole of the flight. The power switch for the imaging subsystem is located on the outside of the box so we can easily activate it on launch day. This subsystem will allow us to image the both the earth and balloon throughout the flight. 3 Management This section contains our mass and monetary budgets, predicted schedule of events, dedication to safety, as well as information about each team member and which tasks they have committed to. 3.1 Organizational Chart Aaryn s production role will be constructing the satellite box with Stephen. She will also be programming and testing the two-channel HOBO with the humidity and temperature sensors. Stephen will be constructing and testing the camera, mirrors, and timing circuit mechanism with Aaryn. Stephen is also in charge of the budget. Scott s production role will be programming and testing the pressure HOBO. He will also be working with Christian and Sheldon to make the magnetometer interface with the two-channel HOBO. Sheldon will also be testing the heater. Christian will also be working on the CAD diagrams. The following is a chart that depicts the above production roles. 3.2 Schedule The following table outlines the extremely detailed schedule we hope to follow for the whole of the semester. The schedule will be updated as the project progresses. Date Task 02/03/2006 Team 12pm discuss and begin Proposal 02/07/2006 In-class build timing circuit 02/09/2006 In-class build heater during class Illegal Survivors Page 9 of 14

10 02/10/2006 Team 12pm discuss and finish Proposal 02/14/ pm Proposal In-class begin Conceptual Design Review Presentation 02/15/2006 Solo finish Conceptual Design Review Presentation 02/16/ pm Conceptual Design Review Presentation slides In-class Conceptual Design Review Presentation 02/17/2006 Team 12:00pm begin Design Document Revision A 02/24/2006 Team 12:00pm finish Design Document Revision A 02/28/2006 In-class complete concrete design 03/02/ pm Design Document Revision A 03/03/2006 Team 12pm acquire all hardware and begin prototyping 03/04/2006 Solo prototyping 03/09/ /10/2006 Team 12pm discuss prototyping progress and modify design begin construction begin Design Document Revision B 03/11/2006 Solo construction 03/16/ /17/2006 Team 12pm discuss construction progress and modify design finish Design Document Revision B 03/18/2006 Solo continue construction 03/20/ /21/2006 In-class begin Critical Design Review Presentation 03/22/2006 Solo finish Critical Design Review Presentation 03/23/ pm Critical Design Review Presentation slides 12pm Design Document Revision B In-class Critical Design Review Presentation 03/24/2006 Team 12pm discuss construction progress begin Design Document Revision C 03/27/2006 Spring Break 03/31/2006 Solo finish construction 04/07/2006 Team 12pm Testing 04/08/2006 Solo fixing components and more testing 04/12/2006 finish Design Document Revision C 04/13/ pm Design Document Revision C In-class bring all hardware 04/15/2006 In-class pre-launch inspection, bring all hardware 04/16/2006 Team 12pm changes after inspection 04/15/2006 Solo last-minute fixes or changes 04/19/ /20/ pm Launch Readiness Review Presentation slides In-class Launch Readiness Review Presentation 04/21/2006 Team 12pm add contact info and US flag to BalloonSat begin Design Document Revision D begin Final Presentation Illegal Survivors Page 10 of 14

11 4:30pm BalloonSat weigh-in and turn-in 04/22/2006 Launch Windsor, CO (leave 5:15am) Team 12pm recover BalloonSat and data 04/23/2006 Solo develop photos and analyze data 04/27/2006 continue Design Document Revision D 04/28/2006 Team 12pm finish Design Document Revision D finish final presentation 05/02/ pm Design Document Revision D Final Presentation slides In-class Final Presentation and Report 4 Budgets The following table includes the estimated mass and monetary budget for this proposed BalloonSat mission. The team will notify Stephen and obtain his approval before any purchases will be made. Stephen will keep all purchase receipts with him and will organize this information on Microsoft Excel to keep track of the monetary budget. Stephen will also organize the mass budget for the satellite. All items have or will be weighed by him in order to make sure that the team stays under the maximum mass requirement. The mass budget will only keep track of the mass actually being flown in space, not the extra parts and testing materials. Part Estimated Mass Estimated Cost Quantity 2-Channel HOBO H g Provided by Space Grant 1 External Temperature Sensor 9.5g Provided by Space Grant 1 Pressure HOBO 18.9g Provided by Space Grant 1 Magnetometer 5g $10 1 Camera 129.3g Provided by Space Grant 1 Film 30g Provided by Space Grant 1 Mirror -5cm x 5cm 10.5g $5 2 Timing Circuit 27.3g Provided by Space Grant 1 12-Volt Battery 4g Provided by Space Grant 3 12-Volt Battery Holder 11.8g Provided by Space Grant 1 Switch (white) 2.8g Provided by Space Grant 1 Heater 16g Provided by Space Grant 1 9-Volt Battery 47.3g Provided by Space Grant 3 Switch (red) 2.7g Provided by Space Grant 1 Foam Core sheet 100g Provided by Space Grant 1 Insulation cm 2 17g Provided by Space Grant 1 Aluminum Duct Tape -169 cm 22.4g Provided by Space Grant 2 Epoxy 5g Provided by ITLL 1 Machining Center Aluminum Axle (20 cm) 50g $10 1 Wires 10g $5 1 Spare Parts 20g $40 NA Illegal Survivors Page 11 of 14

12 Film Development Not Flown $7 3 Film (testing) Not Flown $5 2 Magnetometer (testing) Not Flown $ Volt Battery (testing) Not Flown $ Volt Battery (testing) Not Flown $3 4 Strong Magnets (testing) Not Flown Borrowed from Mike Curl 5 Dry Ice (testing) Not Flown $10 1 Total 701.4g $169 5 Test Plan and Results Many different testing strategies will be applied prior to the launch date. We will need to test the structural integrity of the foam core shell, the cold temperature immunity, and the overall functionality of the satellite. Ideally, we will conduct these four tests two weeks the launch date. 5.1 Structural Test The structural test is one of the most important tests, as it will determine the survivability of the payload, and the structural integrity of the box itself. There are a few techniques and precautions that we must keep in mind while we are testing the box. Our preliminary testing procedure will be a mass simulation method which will include the approximate masses and locations of the hardware inside the box, without actually including the real hardware. During a preliminary design discussion we accidentally discovered an ideal method to simulate the mass. It turns out that a single skittle weighs almost exactly 1 gram. Therefore, for our mass test, we will place the correct amount of skittles in the box prior to performing the test. In this way, we will be able to create a very close approximation of the true conditions of the satellite upon impact with the earth. The actual testing will include the following procedures: Dropping the box from a height of 15 meters. (5 trials) Rolling the box down the stairs to simulate continual impact on the ground. (5 trials) Exerting centripetal forces on the box to simulate the whipping motion the box undergoes during balloon burst by attaching a string through the center tube and swinging it around. (5 trials) 5.2 Temperature Test After being fully assembled with its hardware, the satellite will be placed in a cooler full of dry ice and will stay there for two to three hours. This test will determine the dependability of the heater and will also test the functionality of temperature sensors. We will need to monitor the following things during this temperature test: The time that passes while the object undergoes the test. The internal temperature of the box. (Recorded by HOBO) The external temperature outside the box. (Recorded by HOBO) Illegal Survivors Page 12 of 14

13 A plot of internal temperature vs. time will be overlaid by a plot of external temperature vs. time so that the two can be compared. In this way we will determine the functionality of the HOBO temperature unit, the heater, and a reliable battery life of the heater. 5.3 Camera Test In order to get the types of pictures that we desire, and with a high enough quality to capture good photographs, we will need to test the camera setup. This will include the manipulation of many elements of the imaging system. The mirrors that we will be attaching to the box will not be very far away from the aperture of the camera. In fact, the mirrors will be within a few centimeters of the box. This is where there becomes a potential for bad imaging. The camera itself has an auto-focus characteristic, and we do not want the pictures to be of the mirrors, but rather the light that is reflected off the mirrors. We must therefore determine the optimal distance to place the mirrors from the box. We will try many positions between 3 cm and 9 cm, and record that position with the corresponding exposure number, so that we will know how far away to place the mirrors once we develop the film. 5.4 Final Test The final test will be a run-through of all the functions that will take place during the actual launch of the box. This test will be about 2 hours long, and we will accomplish the following tasks in this order: Switch on box Allow timing circuit to take pictures every 5 minutes Do not move box for 30 minutes as to obtain a constant value from the magnetometer. Drive the box up to Nederland Drive the box back to Boulder. After the above tasks are complete, we must then analyze the data just as if we were analyzing the data of the box post-launch. During the analysis part of the test, the following tasks must be completed: Determine a conversion from the voltage output of the magnetometer to 9.81 m/s 2 Use this conversion to find the acceleration due to gravity in Nederland Determine a conversion from barometric pressure to altitude Use this conversion to make a plot of altitude/time Use this plot to make another plot of acceleration due to gravity vs. altitude 6 Expected Results The science experiment that will be flown on the BalloonSat will be testing the magnetic field strength of the earth as the balloon ascends into the atmosphere. We predict our results to follow the inverse square law that states that the strength of the field is proportional to 1/r 2. Since the balloon is only traveling about 30 kilometers into the air, there Illegal Survivors Page 13 of 14

14 will not be a significant change in magnetic field strength. However, there will be a measurable change that we will be able to calculate with our magnetometer. To discover this change, we will implement the methods described in section 5.4 of this document. Based on currently known equations, the acceleration due to gravity should be approximately 9.6 m/s 2 rather than the near earth value of 9.81 m/s 2. We also expect the max altitude given by the barometer to be very close to 30.5 kilometers. Of course, there is always an evident margin of error when using barometric pressure to determine altitude as it is not a constant value at any altitude. The value is constantly fluctuating at any given point based on the weather. However, the amount that the value of barometric pressure changes is quite negligent when compared to the actual change in altitude that will be present during the mission. Therefore, we must accept that the value will be slightly off, but because the mission is so short, we can use the values to fabricate an accurate plot of altitude vs. time to use with the rest of our calculations. Illegal Survivors Page 14 of 14