Formation Flying

1. Formation Flying Rachel Winters Matt Whitten Kyle Tholen Matt Mueller Shelby Sullivan Eric Weber Shunsuke Hirayama Tsutomu Hasegawa Aziatun Burhan Masao Shimada Tomo Sugano

2. Design • A satellite that will fly escort to the space shuttle • Satellite provides visual inspection of shuttle exterior for 24 hour period of time • Satellite will be transported into space on shuttle • Satellite must meet University Nanosat requirements Rachel Winters (2/30)

3. Previous Work • AERCam “Sprint” • Successfully tested on STS-87 for 1.25 hours around Orbiter • Live video feed • Remote controlled • Mini AERCam • Successful ground tests • Live video feed, including orthogonal view • Remote and supervised autonomous control options http://spaceflight.nasa.gov/station/assembly/sprint/index.html http://aercam.jsc.nasa.gov/ Rachel Winters (3/30)

4. Improvements Our design is... • Completely autonomous • Powered sufficient to operate for 24 hours • Supervision is only necessary for launch and retrieval Rachel Winters (4/30)

5. Systems Integration & Management Rachel Winters, Matt Whitten Major Tasks: • Expendable vs Recoverable spacecraft • Recovery method design • Determine shuttle-interface requirements • Determine picture order Rachel Winters (5/30)

6. Relative Orbit Control & Navigation Kyle Tholen, Matt Mueller Major Tasks: • Determine relative orbit to meet mission requirements • Determine major disturbances from orbit and counteract them • Single vs Multiple spacecraft trade study • Determine thruster equipment • Find Tank size • Determine navigation method Rachel Winters (6/30)

7. Configuration & Structural Design Shelby Sullivan, Eric Weber Major Tasks: • Find camera and lens • Camera field of view analysis • Design structure (material, shape) • Configure component positioning • Mass budget • Solidwork components Rachel Winters (7/30)

8. Attitude Determination & Control Shunsuke Hirayama, Tsutomu Hasegawa Major Tasks: • Determine method of attitude control • Single vs Multiple cameras • Determine pointing accuracy necessary • Determine torque disturbances Rachel Winters (8/30)

9. Power, Thermal & Communications Aziatun Burhan, Masao Shimada, Tomo Sugano Major Tasks: • Determine power needed by satellite • Battery only vs Solar Cell + Battery • Define thermal environment (outside and inside sources) • Determine method of heating • Determine transmission method • Determine differential drag • Integration for CPU Rachel Winters (9/30)

10. Trade Studies • Expendable vs Recoverable Satellite • less expensive to reuse • viable method of recovery • reasonable amounts of extra fuel needed • Single vs Multiple Satellite(s) • amount of extra fuel needed for plane transfers • ability to “see” entire shuttle with only 1 satellite Rachel Winters (10/30)

11. Trade Studies continued • Solar cells + Battery vs Battery only • Amount of power solar cells can provide in 24 hr period • Amount of power needed by satellite components • Size of battery needed to compliment solar cells vs size of battery needed with no recharge • Single vs Multiple camera(s) • Ability to control attitude • Camera size Rachel Winters (11/30)

12. Design Walkthrough • Assumptions and Requirements • Mass restricted to 50 kg • Volume restricted to 60x60x50 cm3 • Necessary to operate for 24 hours, power source must last this long • Assumed an earth-relative orbit that was the same as the ISS orbit • Assumed our shuttle-relative orbit was within safety standards (rp = 118 m, ra = 237 m) Rachel Winters (12/30)

13. Orbit Design • Accuracy of known location/velocity was important • Maintain a “safe” distance away from the shuttle • Remain within camera range Created a general orbit Rachel Winters (13/30)

14. Orbit Design continued • Determined orbital disturbances • J2 disturbances • Drag differences in Low Earth Orbit • This determined the amount of thrust needed to maintain desired orbit Rachel Winters (14/30)

15. Orbit Design continued • Plane change decided • Used a plane change to keep the number of satellites to 1 (Trade Study) • Affects the amount of cold gas needed Rachel Winters (15/30)

16. Satellite Design • We determined the type of attitude control we wanted: zero-momentum • It allows us to control all three axes of rotation • We needed to be able to point at the shuttle at all times • This determined the mode of control: Reaction Wheels • We already needed control to counteract torque disturbances • Aerodynamic torque • Gravity-Gradient torque • Solar radiation pressure torque Rachel Winters (16/30)

17. Satellite Design continued • To simplify the process of calculating torque, we chose to design the center of mass to be in the center of the satellite • We chose to make the satellite a 50x50x50 cm3 cube to simplify the thermal analysis Rachel Winters (17/30)

18. Satellite Design continued We modeled the components and satellite in Solidworks to map out what we wanted it to look like Rachel Winters (18/30)

19. Satellite Design continued • Thermal control designed • Found the temperature range of the environment • Found the temperature tolerance of hardware • Used the mass-based layout to determine necessary thermal control within satellite Rachel Winters (19/30)

20. Satellite Design continued • Power subsystem • Approximated power drain with major components • Made early approximation on battery/solar requirements • Determined number of solar cells we can support • Found power demand including all components • Determined back-up battery requirements Rachel Winters (20/30)

21. Hardware determination • Camera • Small mass, weight; operable in space conditions • This determined an orbit range to stay within Rachel Winters (21/30)

22. Hardware continued • Star tracker • For accurate attitude control, 2 sensors needed • Very accurate (within .001 degree) • Must not be exposed to sunlight Rachel Winters (22/30)

23. Hardware continued • Gyro • Adds accuracy to attitude determination • Included in Reaction Wheel System Rachel Winters (23/30)

24. Hardware continued • Reaction wheel • Used to keep shuttle in field of view • Able to induce up to 50 mNm of Torque Rachel Winters (24/30)

25. Hardware continued • GPS • Differential GPS used for location/velocity information • Light weight • Includes two antennas, two receivers Receiver Antenna Rachel Winters (25/30)

26. Hardware continued • CPU • Provides computer processing for hardware components • Includes several USB ports Rachel Winters (26/30)

27. Hardware continued • Transmitter (wifi) • Able to transmit large amounts of data over orbit range • Connects with USB port • Orbiter must also be connected to wireless network http://www.amazon.com/802-11G-Wireless-Adapt-FROM100-Meters/dp/B000MN8MV4 Rachel Winters (27/30)

28. Hardware continued • Thrusters • Needed to make orbital changes • Cold gas thruster system • Nitrogen Thruster Tank Rachel Winters (28/30)

29. Hardware continued • Battery • Satellite needs power to operate for 24 hours • Use solar cells  minimize battery demand Rachel Winters (29/30)

30. Hardware continued • Heater • Some devices are temperature sensitive • Maintains temperature of satellite within allowable range Rachel Winters (30/30)

31. Demonstration

32. Recommendations for Future Work

33. FMEA

34. Thank you! For all your time and assistance. Mr. Surka Joe

35. Questions? Comments? Formation Flying