1. AAE450 Spring 2009 Attitude Determination in Low Earth Orbit Description: Research Attitude Determination Systems Filter Pertinent Reference Material from Previous Research 1/22/09 Kris Ezra Attitude

2. AAE450 Spring 2009 Attitude Determination Systems  Task: Identify feasibility of using GPS and/or Earth based telemetry in LEO  Method: Compare GPS and an Earth based system –Trimble Advanced Navigation Sensor (TANS Vector) GPS sensor –Mini Dual Earth SENSOR (MiDES) Horizon Sensor  Results: –TANS Vector: Azimuth accuracy between 0.3 and 0.15 degrees RMS (pitch and roll error multiply by 1.5 to 2 depending on installation) –MiDES: Accuracy better than 0.06 degrees (3 Sigma 98.9%) Kris Ezra Attitude

3. AAE450 Spring 2009 Other Issues and MiDES Specifications  No record of independently flown GPS Attitude Device  High speed of parking orbit is outside specifications of TANS Vector device  MiDES will require other sensing units (i.e., reference gyros)  Performance Accuracy: Better than 0.06 deg. 3 sig.  Operational Range: +/- 5.5 deg.  Weight: <1.4 Kg  Dimension: 5.39” x 5.39” x 5.17” (Roughly Cubic Shape)  Power Consumption : <800mW  Operating Temperature: -20 to +60 deg. C Kris Ezra Attitude

4. AAE450 Spring 2009 MiDES Specifications  Performance Accuracy: Better than 0.06 deg. 3 sig.  Operational Range: +/- 5.5 deg.  Mechanical Interface  Weight: <1.4 Kg  Mounting: Mounting flange at base  Alignment: One unit pre-aligned  Dimension: 5.39” x 5.39” x 5.17”  Electrical Interface  Power Input: 28 Volts DC +7/-6 VDC  Power Consumption : <800mW  Environment  Operating Temperature: -20 to +60 deg. C Kris Ezra Attitude

5. AAE450 Spring 2009 TANS Vector Specifications  Azimuth accuracy: –1 meter baselines: 0.30 deg (RMS), typical, application dependent –2 meter baselines: 0.15 deg (RMS), typical, application dependent  Pitch/Roll accuracy: –1 meter baseline: 0.50 deg (RMS), typical, application dependent –2 meter baseline: 0.25 deg (RMS), typical, application dependent  Position accuracy: –25 meters horizontal, 95% of the time –35 meters vertical, 95% of the time –Differential GPS (SA on or off with base station within 500 km) –less than 5 meters horizontal, 95% of the time –less than 8 meters vertical, 95% of the time  Velocity accuracy: –Steady-state conditions, without SA: 0.2 m/sec, RMS –Differential GPS: 0.1m/sec, RMS Kris Ezra Attitude

6. AAE450 Spring 2009 TANS Vector Specifications  Dynamic capability: –Velocity: 400 m/sec –Acceleration: 4 g (39.2 m/sec2) –Jerk: 2g/s (20 m/sec3)  Temperature: –Operating: -40C to +71C –Non-operating: -55C to +85C  Prime power: –9 to 28 Volts DC nominal (32 Volts maximum), nominal 4 Watts  Dimensions: –RPU: 127 mm x 241 mm x 56 mm (5" x 9.5" x 2.2") –Antenna: 96 mm x 102 mm x 13 mm (3.8" x 4.0" x 0.5" maximum)  Volume: –RPU: 1,714 cc (105 cubic inches) –Antenna: 127 cc maximum (7.8 cubic inches) Kris Ezra Attitude

7. AAE450 Spring 2009 TANS Vector Specifications  Weight: –RPU: 1.42 Kg (3.1 pounds) –Antenna: 0.19 Kg (0.42 pounds)  Predicted Reliability: –The estimated reliability based on guidelines of MIL-HDBK-217F. For ground mobile and transport aircraft environments, calculated mean time between failures is greater than 5000 hours. Kris Ezra Attitude

8. AAE450 Spring 2009 References Trimble Navigation Limited. “TANS VECTOR: GPS Attitude Determination System Specification and User’s Manual,” SunnyVale, CA. May 1995 SERVO.COM. “Mini-Dual Earth Sensor,” Acessed 21 Jan 2009, URL:http://www.servo.com/midestd.htm Cohen, C.E. et al. “Space Flight Tests of Attitude Determination Using GPS,” International Journal of Satellite Communications, Vol. 12, 427-433 (1994). Garrison, James. Personal Interview. 21 Jan 2009. Kris Ezra Attitude