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MIDSTAR

MIDSTAR. MIDSTAR TEAM. Caleb Bauer Rebecca Baumez Ethan Biter Paul Camp Katherine Groenenboom Cale Johnson Sean Jones Kevin Yost. AGENDA. Introduction—Col. Smith Structure—Rebecca Baumez Command/Data Handling—Sean Jones Power—Paul Camp & Cale Johnson Main Comms—Katherine Groenenboom

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MIDSTAR

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  1. MIDSTAR

  2. MIDSTAR TEAM • Caleb Bauer • Rebecca Baumez • Ethan Biter • Paul Camp • Katherine Groenenboom • Cale Johnson • Sean Jones • Kevin Yost

  3. AGENDA • Introduction—Col. Smith • Structure—Rebecca Baumez • Command/Data Handling—Sean Jones • Power—Paul Camp & Cale Johnson • Main Comms—Katherine Groenenboom • ICSat—Caleb Bauer & Paul Camp • CFTP —Col. Smith • MIDN—James Bowen • MEMS — Matt Beasley • Launch Operations—Paul Camp • Wrap-up—Col. Smith

  4. MIDSTAR OVERVIEW • MIDSTAR1 will serve as a standard bus which will house several experiments. It will also collect data from each experiment and send the data to the ground station to be processed. It is the first in an intended line of future buses.

  5. MISSION STATEMENT • The mission of MidSTAR I is to design a general-purpose satellite bus capable of supporting a variety of space missions by easily accommodating a wide range of space experiments and instruments.  The integration of the experiments with the satellite bus must be accomplished with minimal changes to the satellite bus design. 

  6. MISSION REQUIREMENTS • Power 28V; >25W Avg Communications 38.4 Kbps • Payload General Bus • Mass < 90.871 kg • Attitude & Control None • Orbit 350-400 km • Lifetime > 1 year

  7. MISSION CONCEPT • Mission Architecture: • Single Spacecraft • Single Ground Station • Delta IV Launch on ESPA Ring • Payloads • ICSat • Configurable Fault Tolerant Processor • MEMS • MIDN • Orbit • Altitude (average) - 462 km • Inclination – 46 • ecentricity - 0

  8. MIDSTAR CONFIGURTION CFTP ICSAT PC-104 EPS COMMS MIDN MEMS

  9. MIDSTAR Structure

  10. Launch Vehicle Structural Requirements • Right handed coordinate frame • Origin at outer edge of attachment ring • 120 kg maximum mass • Center-of-gravity must be less than 20” from origin on +X axis • Useable volume is 24”x 28”x 38” • Fundamental frequency must be greater than 35 Hz • Sustain 10.6g in axial and lateral direction with safety factor of 1.25

  11. Payload and Subsystem Requirements • Must carry: • Main Communications System • ICSAT • CFTP

  12. Design Choices • Chose octagonal structure • High surface area • Flexibility to mount exterior antennas • Must stay within the useable volume given • Three interior shelves • Allows mounting of all components • Utilizes interior volume most efficiently

  13. Description • Material: 6061-T6 Aluminum • Five parts: • Baseplate • L-bracket • Panel • Shelf • Stringer

  14. Assembly Concept • Create five sided bottom assembly, match drilling holes, and rivet structure together. (Step 1) • Insert interior shelves and match drill holes for screws.(Step 2) • Create three sided cowling assembly, match drilling holes, and rivet structure together. (Step 3) • Install self-locking nutplates, match drill screws for solar panels. • Add inserts and mount boxes to lower and upper decks. (Step 4) • Add inserts and mount boxes to three interior shelves. (Step 5) • Insert interior shelves and attach with screws.(Step 6) • Bolt cowling assembly. (Step 7) • Install solar panels.

  15. Fasteners • Rivet • 1/8” diameter • 2117-T4 aluminum alloy solid rivets • MS 20426AD countersunk head • MS 20470AD round head • Nutplate • NAS 1773 • Self-locking • Stainless steel • Socket head cap screws • NAS 1352 • A-286 Stainless steel

  16. Mass Budget

  17. Center of Gravity & Moments of Inertia

  18. Finite Element Model • Proved natural frequency is above 35 Hz • Based on skeleton assembly of structure Meshed: • Lightband • Eight side panels • Two interior shelves • Exterior end shelf

  19. Validity Checks • Free edge checks • Indicate misalignment • Indicate location of coincident nodes • Coincident node check • Combined or eliminated duplicates to increase quality of FE model • Mass properties information • Mass properties of mesh matched the mass properties of the structure

  20. Boundary Conditions • Clamped at lightband side of structure • Simulates attachment to ESPA ring • Other surfaces were rigidly attached to each other • Simulates bolts and rivets throughout the structure

  21. Results: Mode 1 • Frequency: 150.1631 Hz (lowest frequency) • Displacement: 1.93 E –01 mm • Comments: Drumming effect

  22. Mode 2 • Frequency: 162.846 Hz • Displacement: 2.18 E –01 mm • Comments: Cantilever beam effect

  23. Mode 4 • Frequency: 165.7479 Hz • Displacement: 1.93 E –01 mm • Comments: Drumming effect

  24. Mode 6 • Frequency: 335.3364 Hz • Displacement: 6.91 E –02 mm • Comments: Drumming effect, significantly higher frequency than natural frequency

  25. Mode 8 • Frequency: 349.5273 Hz • Displacement: 1.04 E –01 mm • Comments: Torsion

  26. Mode 10 • Frequency: 351.9548 Hz • Displacement: 7.24 E –02 mm • Comments: Torsion/Drumming

  27. Backup Slides

  28. MidSTAR-1 COMMAND AND DATA HANDLING SYSTEM

  29. Command & Data Handling: Requirements • 50 MHz processor • 32 MBytes of RAM • 50 MBytes of storage • Synchronous Serial Ports • Asynchronous Serial Ports • 128 Analog Inputs • 32 Digital Control Lines

  30. Command & Data Handling: Implementation • 133 MHz PowerPC processor • 128 MBytes of ECC SDRAM • 384 MBytes of storage • 2 Synchronous Serial Ports • 6 Asynchronous Serial Ports • 128 Analog Inputs • 56 Digital Control Lines

  31. Requirements on Bus • 5V Power • Room for 2 10”x10”x4” weighing 5 kg ea. • -40 - + 80 degrees Centigrade • 10% - 80% humidity

  32. Hardware Block Diagram

  33. Software Block Diagram

  34. Network Flow Diagram

  35. Power Budget

  36. Fiscal Budget

  37. MidSTAR-1 ELECTRICAL POWER SYSTEM

  38. Power System Requirements • General Purpose Bus • 28V; >25W Avg Power • Have 6.5”x28” available per side for solar panels • Battery Capacity: 42W-hr • Battery charging system • Power distribution system with: • ability to supply various voltages • commandable switching and short-circuit protection Solar World Space-Rated Cells

  39. Power Flow Schematic T/V: Telemetry/Voltage T/C: Telemetry/Current

  40. Power Budget / Duty Cycle(Main Comms X-mit)

  41. Power Budget / Duty Cycle(ICSat X-mit)

  42. Design Decisions • 2 6.5”x14” panels per side; 16 total • 1 GaAs: 27% efficiency • 1 Silicon: 15% efficiency • 8 GaAs cell panels, 8 Silicon cell panels. • 24 Sanyo NiCd cells in each battery; all cells lined in series • D size, 4.4A-hr • Thermal Interface between panels and structure • Battery board designed with PCB Express

  43. Solar Panel Arrangement Si Si GaAs GaAs GaAs Si

  44. Parts List / Budget

  45. MidSTAR-1 COMMUNICATIONS

  46. Main Comms Requirements • Accommodate experiments • BER: 2x10^-5 (CFTP) • Data rate: 100 kbps (CFTP) • Temperature: -20° C to 70° C (ICSat) • Humidity: 30% to 80% (ICSat) • Frequencies • Uplink is 1.767 GHz • Downlink is 2.20226 GHz • Use NPS for back-up ground station

  47. Link Budget

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