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  1. PDR-Preliminary design review 2 May 2012 Luis Carrillo Vanessa Elleson Ian Neel Sam Mutschler Andrew Tucker David Wallace

  2. Table of Contents Concept of Operations Work Breakdown Structures (WBS) Communications Structures Power Systems Guidance Navigation and Control Command and Data Handling Visual Data Configuration Management Project Schedule Cost Budget

  3. Concept of Operations • Launch • Initialization • Simultaneous release of Texas A&M satellite and Target • Stop “moving” within two minutes of release from ESPA Ring (3.5.1) • Rotational Rates: ±0.5 [deg/sec] • Translational Rates: ±2 [cm/sec] • GPS Functionality • Calculate Relative Navigation Solution and Absolute Position • Maneuver 1-RCS Test (3.5.2) • Maneuver 2-Approach Target (3.5.3) • Maneuver 3-Move around Target (3.5.4) • Maneuver 4-Dock with Target (3.5.5)

  4. Concept of Operations 7. Maneuver 2-Approach Target (3.5.3) 0 5m -vbar +vbar

  5. Concept of Operations 8. Maneuver 3-Move around Target (3.5.4) +rbar + 5m + 5m Target Zelda -vbar +vbar - 5m -rbar

  6. PHASE A: WORKBREAK DOWN STRUCTURE

  7. PHASE B: WORKBREAK DOWN STRUCTURE

  8. Communications Andrew tucker

  9. System Overview Spacecraft UHF Downlink/Crosslink (LDR) VHF Uplink (LDR) S-Band Downlink (HDR)

  10. Low data rate (ldr) system • Astrodev Helium 100 • VHF/UHF Amateur Frequencies • Up to 38.4 kbps data rate • 3 W RF output • AX.25 Packet Acknowledgement • Flexible monopole antennas released by burning through monofilament wire • Two Units, VHF Up, UHF Down/Crosslink • Either can function as uplink in emergencies • 18.7 dB UHF / 14.4 dB VHF Link Margin with Ground Station at 250 mi (400 km) altitude, 10o elevation 10

  11. high Data rate (hdr) system • ClydeSpace CPUT-STX-805-001 • 2.4 GHz Amateur Frequencies • 1 W RF output • Up to 2 Mbps data rate (1/8 will be used) • High Gain Patch Antenna (8 dBi) • 4.0 dB Link Margin with Ground Station at 250 mi (400 km) altitude, 10o elevation

  12. Download budget assumptions • 12 min 43 sec available ground pass time per day, calculated with orbit tracking software • 20 % Packet Loss Rate (PLR) • 50% Ground Passes Missed

  13. Download budget [2]

  14. Communications on the move • New application of satellite telephone technology currently under development by AggieSat Lab • Utilizes Iridium Satellite Communications Network • Communicate without line of sight • Iridium model 9523 Internet Modem • > 21% orbit coverage at 250 mi (400 km) altitude • Approximately 6600 Mb data over estimated mission lifetime (4.2-6.4 months, 41.5 Mb/day)

  15. Download times • Thumbnails generated to downlink all images captured • Thumbnails used to select Full Resolution Images for Downlink

  16. FMEA

  17. Structure David wallace

  18. Launch Vehicle • Falcon 9 Launch vehicle • Circular orbit from 200 – 2000 km • Inclinations from 28.5 – 51.6o • LEO Mission accuracy • Perigee/Apogee ± 10 km • Inclination ± 0.1o • Right Ascension of Ascending Node ± 0.15o

  19. Launch Environment • Maximum axial acceleration 6 g • Maximum lateral acceleration 2 g • Fundamental bending mode greater than 10 Hz • Fundamental axial mode greater than 25 Hz • Temperature exposure up to 200 oF

  20. Launch Environment

  21. Separation system • Lightband Separation system by Planetary Systems Corporation • 15” diameter Lightband • 6 springs

  22. Material selection • Aluminum 6061-T6 for all structural components • High strength to weight ratio • Low cost • Easy to machine • Standard satellite bus material • Parts ordered from onlinemetals.com

  23. Mass Budget

  24. Spacecraft Overview Iridium Patch Antenna LDR Uplink Antenna Top View Isometric View LDR Downlink/Crosslink Antenna GPS Antenna Rear View Left View HDR Patch Antenna

  25. Internal Layout Upper Face Iridium Radio Right Face STX HDR Radio He 100 Radio (x2) Front Face Bottom Face Rear Face ECB GPS IMU Left Face CDH Unit Sun Sensor

  26. Analysis Assumptions • Structural mass of 72.18 lbs and applied mass distributed over fuel tank of 71.12 lbs • 14 g axial acceleration, 4 g lateral acceleration • Factor of safety: 2

  27. Static Analysis • Results • Max stress of 34.394 ksi • Max displacement of 0.214”

  28. Vibrational Analysis

  29. Thermal Analysis • Spacecraft Energy Balance Qout Qin, Earth albedo Qin, Earth Qin, Sun Qinternal

  30. Failure Mode and Effects Analysis (fmea)

  31. Future Developments • Include internal plumbing and wiring • Refine static and dynamic analysis with greater computing power • Thermal analysis • Insulation design and passive thermal controls • Design docking mechanism

  32. Power system Ian neel

  33. Power Generation • Solar Cells • Spectrolab UTJ Gallium Arsenide cells • Max power output 31.5 W/ft^2 • Body mounted panels with active solar alignment for optimal energy harnessing

  34. Power Generation Y X Z Theta (rotation about the Z axis) Phi (rotation about the X Axis)

  35. Power Distribution • Clyde Space SmallSatmodular electrical power system • Provides benefits such as maximum power point tracking for solar panels • Power distribution unit featuring dc-dc converters for conversion from solar power to supply power to other subsystems • Safety circuitry for over voltage and over current protection. • Expected efficiency of 95% • Modular for addition of various supply voltages

  36. Power bUDGET

  37. Power Storage • Secondary Batteries • Lithium ion cells • Panasonic CGR-18650E • Typical capacity 2500 mAh, 3.7V • Maximum charge rate 0.7C • Battery of 8 cells in series for desired 30V, • Two of these strings in parallel to increase capacity and limit Depth of Discharge for increased battery life. • Two batteries included for redundancy

  38. Power Storage • Battery Performance • Operational temperature range • Charge (32º to 140º F) Discharge (-4º to 140º F) • Battery monitored and heated by power supply system to maintain optimal charging and discharge rates

  39. SYSTEM OVERVIEW Load Solarpanels Battery charge regulators (approx. 6) PowerDistributionmodule Battery Battery BCM shunt

  40. Fmea

  41. Future Work • Battery duty cycles for better battery sizing • Simulation of system in orbit to more accurately determine power requirements for various flight phases • Current estimates are worst case scenario Battery box design and placement • Design of battery enclosure and insulation

  42. Guidance, navigation, and control Vanessa elleson

  43. Sensors • Surrey Satellite Technology • Sun Sensor, • Magnetometer • GPS • Gyroscope • Magnetorquers • Servo Corporation • Horizon Sensor • Sinclair Interplanetary • Reaction Wheels • Vernier Software and Technology • Accelerometer

  44. Thruster Components Self Manufactured • Tank • Fuel • Regulator • Isolation Valve • Drain Valve Moog Inc. • Thruster Valve

  45. Fuel Assumptions: • Pressure in tank: 3872.4 [psia] • Temperature in tank: 67.7 [F] • Mass of spacecraft: 143.3 [lbs] • Density of Nitrogen: 17.7 [lb/ft^3] • Distance to target: 780.8 [ft] Calculations: Velocity exit = 2163.7 [ft/s] mdot = 8.1 [lbs/second] Isp = 67.2320 [seconds] deltaV = 308.4 [ft/s] Mass of fuel = 15.77 [lbs] Volume Total = 0.777 [ft^3] Tank Mass = 6.99 [lbs]

  46. Design

  47. FMEA

  48. Future Work • Orbital Simulations • Control Law

  49. Command and data handling & Visual Data Luis carrillo

  50. CDH Requirements • Autonomous Program • Components • Accelerometer • Sun Sensor • GPS • Magnetometer • Horizon Sensor • Gyroscope • Magnetorquers • Reaction Wheels • Infrared Camera • 4 antennae/Radio • Port Types • 1 – RS422 Serial Ports • 2 – DB15 • 1 – DB9 • 1 – SCSI • 2 – PCI Bus • Data Requirements • Total Sensor Rate • 38 kb/s • Infrared Camera Rate • 2 MB/s • Memory Needed • 8 GB