This is the slide show from our preliminary design review for our Junior Engineering Project.

1. Preliminary Design ReviewTeam ESAT Caleb Carroll Marc Cattrell Elliot Chalfant Luke Dornon Zach Vander Laan David Zilz Advisors: Dr. Hank Voss Mr. Jeff Dailey Taylor University Junior Engineering Project PicoSatellite 1

2. What is a PicoSatellite? Satellite some where between 0.1-1 kg Often flown in groups of 3 or more How Does is differ from a regular satellite? Lower Orbit Able to reach unexplored areas of Atmosphere Lower Cost Introduction 2

3. TubeSat Able to fit into tube for InterOrbital Flight Deployable from tube ready for orbit Withstand launch conditions CubeSat Constellation of PicoSatellites Fit 4-5 smaller satellites into CubeSat Project Scope 3

4. Why are we doing this? Small Size/Weight/Cost Modular (Compatibility w/ other system) Stability Control Power Management Solution for Thermal Problems Scientific Instruments Project Requirement 4

5. Work Breakdown Structure 5

6. Block Diagram 6

7. System Requirements 7

9. Sensor orientation (Plasma Probe, Magnetometer)

10. Power constraints (Solar Panels)

11. Aerodynamics1.7 Attitude Control 8

12. Permanent Magnet 2 Permanent Magnets (perpendicular orientation) Motor-controlled Magnet Permanent Magnet with Magnetic Torquer Magnetic Torquers for 3 axes Reaction Wheels / Thrusters Gravity Gradient Boom Attitude Control - Options 9

13. Solar panels on both sides of satellite From power standpoint do not need to control satellite’s roll Advice from Taylor Engineering alum Strongly urged us to scale back scope of project Simple magnetic stabilization would be sufficiently difficult for semester - long project  Use permanent magnet as method of attitude control Attitude Control – Narrowing the Scope 10

15. Magnetic torque due to interaction between permanent magnet and Earth’s magnetic field

16. Need magnetic torque to be greater than any other torque on satellite

17. Satellite will track the magnetic field of the Earth, rotating twice per orbit.[1] [2] 11

18. At orbit of r=310km and T=1000K: For altitudes below 500km, drag force dominates all other forces (such as radiation) [3] Permanent magnet controls 2 axes (pitch and yaw) but roll appears to be unconstrained. While satellite may be able to roll over equator, it will not be able to do so near the poles  Drag force constrains the 3rd axis Two surfaces of satellite will be in Ram direction during different parts of orbit These surfaces due to drag force are working against magnetic torque How large are these torques in a worst case scenario? Attitude Control – The Drag Force 12

19. Worst case scenario for torque due to drag force: 10’’ x .583’’ surface Highly concentrated group of molecules hit only one half of the surface Magnetic torque must be greater than this torque for optimal attitude control at this altitude Attitude Control – Calculating Drag Force Torque 13

21. Experimental Refinement Oscillation Damping Viscous fluid Hysteresis Rod Magnetic Placement Orbit Simulation Time Spent / Usefulness tradeoff Attitude Control – Issues to Consider 15

22. [1] http://oceanexplorer.noaa.gov/explorations/05galapagos/logs/dec22/media/magfield_600.html [2] Bopp, Matthew, and Jonathan Messer. An Analysis of Magnetic Attitude Control of Low Earth Orbit Nano-satellites with Application for the BUSAT. BUSAT. Attitude Control and Determination Subsystem. Web. 01 Mar. 2010. [3] Fundamentals of Space systems [4] Physics for Scientists and Engineers (Giancoli) Works Cited 16

25. TWIN HINGED BOARDS

28. TWIN HINGED BOARDS

30. CASING (E&M SHIELDING)

32. PRESERVE ENCLOSURE SYMMETRY

34. What We Expect to Find Current From Charged Particles Graph Shows Current vs. Swept Bias Voltage 23

35. Plot of a Log Scale Electron Temperature Temperature of Given Electron Distribution Plasma Potential Average Electric Potential Between Particles What Do We Use This For? 24

37. Built on Individual Circuits

38. Ease of Transferability

39. Redundant SystemTo Command Interface Magnetic Field Readings Plasma Readings 25

40. Deployable Sensor Booms Fiberglass Rod Langmuir Plasma Probes Magnetometer Folding Sensor Booms Plate Plasma Probes 1cm x 3cm Gold Plated Units Coaxial Cable Directly Through Wall Opposite Corners of Satellite History of Design 26

41. Electrical Schematic 27

42. Past: Decide on Final Design of Probes Right Now: Have Electrical Schematic Have most of the parts Next Step: Assemble Circuitry Test Circuitry Timeline 28

43. Collecting Good Data Staying Out of Wake Far enough away from craft Transmitting Data Back to Earth for Analysis Long Enough Orbit for Good Results Stable Flight Thanks to Attitude Control Issues/Risk Assessment 29

44. Power management concept Energy supplied by GaAs solar panels Energy stored in batteries Energy provided to entire electrical system for in-flight operation 1.5 Power Management 30

45. Goals: Determine power supply capabilities of solar panels and batteries Regulate power usage in the satellite for maximum data acquisition/transmission Requirements Supply sufficient power for operation of essential satellite systems Sustain power supply for estimated 3 month flight Power Management Objectives 31

46. Power Supply Diagram 32

47. Power Usage Diagram 33

48. Batteries 4V Batteries Rated for 875mAhr (3500mWhr) Solar Cells Rated for 14mA/ square cm at 2V Our cells can provide 400mA max (800mW) Power Supply Specifications 34

49. Assumptions used to create a baseline power supply estimate: Solar panels produce full current when pointed at the sun within a 45 degree angle. Atmospheric reduction of solar energy is negligible. Satellite follows a polar orbit. Satellite attitude is primarily controlled by a fixed magnet aligning with earth’s magnetic field. Solar Panel Power Estimation 35

50. Baseline Solar Power For a noon-midnight orbit satellite magnetic control causes solar panels to point away from the sun for a portion of a noon-midnight orbit in addition to the significant portion of orbit behind the earth’s shadow. For a dawn-dusk orbit the sun’s rays come out of the screen and thus hit the satellite for its entire orbit. Sunlight Earth’s Shadow Orbital Path 36

51. Baseline Solar Power II Sunlight Direction of Satellite Magnetic Field Line Solar Cells Parallel to Sunlight Solar Cells Perpendicular to Sunlight With a single fixed magnet to control attitude, the satellite is free to rotate around magnetic field lines. Even when the field is perfectly perpendicular to the panels the rotation could cause the cells to see sunlight only 50% of the time (two sides have panels giving a 90 degree angle of effectiveness). 37

52. Using all the previously discussed estimation factors, the baseline or minimum expected solar power can be calculated. Baseline Solar Power III 38

53. Based on our Solar Power estimates, the average solar power supply should be roughly 0.5W, but this will not be continuously available. Our batteries must store power and supply it when the solar panels are inactive. The number of batteries launched will depend on the space and weight restrictions of our satellite after other components are installed. Batteries 39

54. Power Usage Specifications Total = 510 mW 40

55. Our solar power estimates may prove to be too high for our real orbit. Our transmission hardware requires large amounts of power compared to our supplies. Aerodynamic forces may prevent rotation around the magnetic field lines resulting in solar cells never facing sunlight for up to a three month period. Potential Issues 41

56. Refine Power Supply Estimate Measure actual solar cell power output over varying solar incidence angles Refine orbit model following finalized attitude control design Scheduled for the first 2 weeks of April Optimize component duty cycles Construction/Integration Install power supply systems Test functionality Scheduled for final 2 weeks of April, first 2 weeks of May Future Work 42

57. 1.3 ESAT Communications System Primary Link Axonn satellite module Frequency range: 1611.25 – 1618.75 Mhz ( Globalstar ) Data rate: 9600 144 Byte packet burst mode. Antenna: Compact microstrip patch antenna L1 band Gain: 5.7dB 25mm x 25mm x 2mm Current: 500mA (Tx) Secondary Link Maxstream spread spectrum module Frequency range: 902 – 928Mhz ( ISM band ) Data rate: 9600 – 57.6kb Data encryption: 32bit Antenna: Collinear 7.5dB RF Power: 1W Current: 700mA (Tx) Inventek GPS Module Firmware: Taylor HankEYE V2.1E ( No restrictions ) Channel: 20 Update rate: 20Hz Data rate: 115.2kb Current: 25mA Antenna: Active patch L1 band 28db gain 25mm x 25mm x 2mm 43

58. ESAT Communications System Globalstar satellite network 1611Mhz ESAT 900Mhz Globalstar Ground Station Internet Taylor Ground Station 44

59. ESAT Communications System Taylor ground station Communications: Dual Maxstream 900Mhz ISM Module Tracking: Az / Elv satellite antenna tracking system Antenna: 47dB Axial mode helical stack Software: Sequel server database / LabView user interface / AGI satellite interface Communications protocol HawkEYE packet structure ( high speed micro burst packet ) Packet size: 44 Byte CRC: 16 Bit GPS position Instrument data System data 45

60. ESAT Control Module 46

61. Next Steps Attitude Control Magnet Finalization Experimental Refinement Mechanical Drawing Finalization Enclosure Sensors Circuitry Finalization Power Management Final Power Calculations Circuitry Construction Communication Circuitry Design and Testing 47