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What is GEONS?

What is GEONS?. Russell Carpenter. GEONS Performs Onboard Navigation. Flight-proven Award-winning NPR 7150.2 Compliant UD-Factorized Extended Kalman Filter ANSI standard C with object-oriented techniques GPS, TDRSS, DSN/USN/GN, Crosslink, Celestial Object, Accelerometer measurements

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What is GEONS?

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  1. What is GEONS? Russell Carpenter

  2. GEONS Performs Onboard Navigation • Flight-proven • Award-winning • NPR 7150.2 Compliant • UD-Factorized Extended Kalman Filter • ANSI standard C with object-oriented techniques • GPS, TDRSS, DSN/USN/GN, Crosslink, Celestial Object, Accelerometer measurements • One or more user satellites, alone or simultaneously • Earth, Moon, LPOs, Deep Space

  3. GEONS Core Algorithms and Software have 20+ years of Flight Heritage • Ground-based experiments on Landsats 4 & 5, COBE (1980s) led to series of experiments onboard EUVE (1990s) • EUVE code formed basis for • TDRSS Onboard Navigation System (TONS) now providing operational OD for Terra • Enhanced Onboard Navigation System (EONS) that was integrated into the Command Receiver (forerunner to GD’s MMT) • Celnav that was tested on the ground with POLAR and SOHO data • TONS modified for GPS Enhanced Orbit Determination Experiment (GEODE) on Lewis (1996) • GEODE “Lite” developed for EO-1 Autocon formation flying (2000) • GEODE software licensed to Orbital and Ball, has flown on numerous missions including Microstars, Orbviews, SORCE, CALIPSO • GEODE embedded in ITT Low Power Transceiver and flown on STS-107 CANDOS experiment • GEONS = GEODE + EONS + Celnav (2001 - present) • Simplified software maintenance with one set of source code; compile with only options needed • Integrated with Navigator GPS for MMS and GPM

  4. Recognition and Compliance • Awards • 2000 Runner-up for NASA Software of the Year • 2004 Federal Laboratory Consortium Mid-Atlantic Regional Excellence in Technology Transfer Award • 2007 NASA Software Release Award • NPR 7150.2 Compliance • Development of all core capabilities occurred prior to NPR 7150.2 (see previous slide) • High-level requirements were documented in the “Software Requirements Specifications” • Detailed requirements were documented in the “Mathematical Specifications” • “As-built” design was documented in the “System Description & User’s Guide” • 7150.2 Compliant Software Maintenance Plan currently in effect • Automated SCM, document repository, and issue tracking database in use by all project personnel

  5. More Details Performance

  6. Navigator Flight Unit 1A HWIL Testing for MMS Phase 2B 12 10 8 6 4 2 0 Number of GPS MMS Phase 2b, 1.2 x 25Re

  7. CislunarNav with GPS and Translunar Relay Spacecraft receives GPS pseudorange enroute to Moon Pair of Relay Satellites at L2 provides one-way Doppler

  8. Celestial Navigation with ACS Sensor Data from HEO Spinner (POLAR) • 1.8 x 9 Re Orbit, 10 RPM • Limited data: four 1-2 hour contacts over 4 days • “Truth orbit” • Ground-based 2-way Doppler solution • Accuracy ~1 km • Attitude • Ground-based definitive • Accuracy ~6 arcmin • Simulated sensitivity to attitude bias: Horizon Sensor Measurement Sun Sensor Measurement

  9. More Details Algorithms

  10. Dynamics Models

  11. Estimator Models

  12. Measurement Models and Cold Start

  13. Other Models

  14. Benchmarks for GEONS 2.1 (~2003) • GNU Profiler used to obtain average number of FLOPs per state update call over 10 samples in various configurations, compiled with full optimization • Four user satellites in 1.2 x 12 RE orbit with 24-hour period • Up to 12 GPS available below 3 RE; fewer than 4 GPS above 9 RE • All cases used 10-sec propagation time-step and 35 day time span

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