1 / 46

FLIGHT DYNAMICS OPERATIONS FOR THE INTERSTELLAR BOUNDARY EXPLORER

FLIGHT DYNAMICS OPERATIONS FOR THE INTERSTELLAR BOUNDARY EXPLORER. Lisa Policastri Lisa@AppliedDefense.com AGI Users’ Conference Tour, Greenbelt, MD 12 July 2010. IBEX Background. NASA Small Explorer Program (SMEX) Southwest Research Institute, principal investigator

leola
Download Presentation

FLIGHT DYNAMICS OPERATIONS FOR THE INTERSTELLAR BOUNDARY EXPLORER

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. FLIGHT DYNAMICS OPERATIONS FOR THE INTERSTELLAR BOUNDARY EXPLORER Lisa Policastri Lisa@AppliedDefense.com AGI Users’ Conference Tour, Greenbelt, MD 12 July2010

  2. IBEX Background • NASA Small Explorer Program (SMEX) • Southwest Research Institute, principal investigator • Launched from Kwajalein Atoll on 19 October 2008 • Launched on Pegasus with STAR-27 SRM • Highly elliptical orbit, approximate: • Apogee altitude of 48 Re • Perigee altitude of 7,000 km • Period of 8 days • Operational lifetime of at least two years • Three orbit-raising maneuvers to achieve mission orbit • Spinning spacecraft, sun-pointed • Tracked by Universal Space Network (USN) + APL www.AppliedDefense.com

  3. IBEX Orbit www.AppliedDefense.com

  4. IBEX’s Science Objectives • IBEX's sole, focused science objective is to discover the global interaction between the solar wind and the interstellar medium • IBEX achieves this objective by taking a set of global energetic neutral atom (ENA) images that answer four fundamental science questions: • What is the global strength and structure of the termination shock? • How are energetic protons accelerated at the termination shock? • What are the global properties of the solar wind flow beyond the termination shock and in the heliotail? • How does the interstellar flow interact with the heliosphere beyond the heliopause? www.AppliedDefense.com

  5. IBEX Flight Operations Team • Mission Operations Center (MOC) at Orbital Sciences in Virginia • Flight Dynamics (FDG) operations at Applied Defense Solutions in Maryland • Program Management at Southwest Research Institute in Texas www.AppliedDefense.com

  6. IBEX Flight Dynamics Info • Flight dynamics operations at ADS • Three tracking contacts every orbit • One attitude maneuver every orbit • Orbit determination after each contact • Product delivery requirements per orbit • Acquisition files: TLEs and INP2s… • Ephemeris predicts… • Ground station view periods • Star tracker outage predictions • Orbit events information • And more! www.AppliedDefense.com

  7. IBEX Flight Dynamics Group • Lisa Policastri (FD lead) • Ryan Lebois • John Carrico • Marissa Intelisano • Craig Nickel • Mike Loucks (Space Exploration Engineering) • FDG activities 40 hours per week total max! • Must have efficient & reliable tools & software!!! www.AppliedDefense.com

  8. IBEX Flight Dynamics Software • Satellite Tool Kit (STK) 8.1.3 • Astrogator + Professional Edition + Integration + Attitude • Recently added STK/Communications! • Orbit Determination Tool Kit (ODTK) 5.1.2 • Microsoft Excel 2007 • WSFTP 2007 • Scripts & Utilities (custom workflows) AGI software + custom workflows supports all flight dynamics operational needs for IBEX www.AppliedDefense.com

  9. Equipment • Desktop • Antec Quad-Core Xeon Processor • Configured for all flight dynamics activities • Backed up to ADS secure server • Network Connection • SFTP • e-mail • Blackberry • Modem • Communicating with friends at the MOC • Backup laptop • Dell Precision M4300 Laptop www.AppliedDefense.com

  10. Operational Flow Stages “High Level” ODTK STK Utilities • Data Products: • Definitive Ephemeris with Covariance • Predict Ephemeris with Covariance • TLEs & INP2s • View period predicts • Star tracker outage predicts • Orbit events files • Long-term analysis Planned Maneuvers QC Tracking Measurements www.AppliedDefense.com

  11. Planned Maneuvers - Validate • Mother-of-all IBEX STK scenarios • Originally called “IBEX ATS” scenario • Script that reads in ATS files • Models spacecraft attitude www.AppliedDefense.com

  12. Attitude Check www.AppliedDefense.com

  13. Pre-screen Tracking Files • Grab • Load • Preview • Time period? • Correct IDs? • Gaps with file? • Missing files? www.AppliedDefense.com

  14. Pre-Processing Tracking Measurements: ODTK Preview • Measurements are preprocessed in ODTK • Displayed summary information about each measurement file • Tracking station identification • Start and stop times of the measurements • Number of valid measurements in the file • Warning if the measurements are: • Out of order, then run ODTK “Sort UTDF Observation File” Utility • Not valid www.AppliedDefense.com

  15. Pre-Processing Tracking Measurements: UTDF Reader • Read binary measurement files in the UTDF format. • “Tracking and Acquisition Handbook for the Spaceflight Tracking and Data Network,” • Displayed about measurements: • Ground station identification codes • Record date and time • Tracking mode: program track or auto-track • Doppler is valid or invalid • Allows editing of data in binary files, if records showed to be mis-tagged or out of order. • Allows exporting of information • Auto-track records (angle measurements) • Doppler measurements • STK Sensor Pointing files (auto-track) www.AppliedDefense.com

  16. ADS UTDF Reader www.AppliedDefense.com

  17. ODTK Configuration • Continuous ODTK scenario • Ground stations geodetics • Biases and bias sigma estimates • For each measurement type • For each station • From measurement statistics • Refined over time as needed www.AppliedDefense.com

  18. Running ODTK Filter • Run ODTK Filter • ODTK Static Product Builder: custom graph & report product list • Histograms of residual ratios per station, per measurement type • Measurement Residuals per station, per measurement type, +/- 3 sigma • Measurement Residuals all stations, per measurement type, +/- 3 sigma • Residual Ratios (normalized residuals), per measurement type • Position uncertainty • Velocity uncertainty • Measurements locations along orbit as a function of spacecraft altitude • Measurements locations along orbit as a function of spacecraft true anomaly • Measurement summary • Results in histograms, residuals, and residual ratios are examined to determine if the Gauss-Markov parameters needed adjustment www.AppliedDefense.com

  19. Doppler Residual Ratios Example • Bias Sigma, half-life, and white noise sigma adjusted if: • Too much “white space” in the residual ratios graph • Histograms were not showing Gaussian distributions • Measurements with residuals outside of +/-3 sigma were not accepted by filter www.AppliedDefense.com

  20. Example of Histogram of Residual Ratios • Hawaii station • Filtered Doppler measurements (14,835 samples) www.AppliedDefense.com

  21. Filter 3-Sigma Position Covariance Radial uncertainty is blue, in-track is red, cross-track is black www.AppliedDefense.com

  22. Filter 3-Sigma Velocity Covariance Radial uncertainty is blue, in-track is red, cross-track is black www.AppliedDefense.com

  23. Current Measurements by Altitude www.AppliedDefense.com

  24. Running ODTK Smoother • Each successful filter run followed by corresponding smoother run • Smoother refines the state & covariance from the filter • Provides improved orbit accuracy with a smoothed ephemeris & covariance • Solves for maneuvers • Products generated after each smoother run • Smoothed position uncertainty • Smoothed velocity uncertainty • Maneuver summary reports www.AppliedDefense.com

  25. Smoother 3-Sigma Position Covariance Radial uncertainty is blue, in-track is red, cross-track is black www.AppliedDefense.com

  26. Smoother 3-Sigma Velocity Covariance Radial uncertainty is blue, in-track is red, cross-track is black www.AppliedDefense.com

  27. Running Filter & Smoother • Modified State Diff tool installed w/ ODTK • Automates file naming and storage • Automates pointing to various files for: • Smoother (rough file) • Static Product Builder • .Filrun • .Smtrun • .Difrun www.AppliedDefense.com

  28. Filter-Smoother Differencing • Position and velocity consistency tests are an important quality check • If differences in the filtered and smoothed ephemeris solutions were outside of three sigma, go back and re-examine data • Differencing process is handled by the ODTK “State Difference” utility • Position and Velocity Consistency graphs are generated www.AppliedDefense.com

  29. Filter-Smoother Position Consistency Check • 3-sigma bounded • Radial uncertainty is blue, in-track is red, cross-track is black www.AppliedDefense.com

  30. Filter-Smoother Velocity Consistency Check • 3-sigma bounded • Radial uncertainty is blue, in-track is red, cross-track is black www.AppliedDefense.com

  31. Ephemeris with Covariance • Each ODTK filter run & smoother run produced ephemeris files • With 6 x 6 position & velocity covariance • STK .e file format • Contain definitive and predict points • Smoother ephemeris files contain: • Definitive ephemeris from filter restart point until time of the last measurement • Four orbits of predictions • Smoother ephemeris files imported into STK • Spacecraft position graphically displayed • Position covariance ellipsoids displayed in 3-D • Compare differences in solutions • Graph the angle between spacecraft position • Look for covariance in ground station FOV www.AppliedDefense.com

  32. Smoother Definitive & Predict Ephemeris with Covariance www.AppliedDefense.com

  33. Predict Ephemeris Delivered • Smoother (or filter) ephemeris files used for generating the official delivery of predicted ephemeris • State at last measurement used in STK/Astrogator for initial state • Prediction files needed for scheduling ground station contacts • Prediction files used to create acquisition data for the ground stations • INP2 angle files • TLEs • SPICE www.AppliedDefense.com

  34. Acquisition Data Types • TLEs primary (initially) • Selected years ago for pointing antennas • Tested for a typical nominal operations cases • INP2 angle files • Contain azimuth & elevation angles at specified time steps over a period of time • Highly elliptical orbits • STK Access Custom report style • SPICE predict ephemeris for APL station • IIRV for NASA stations www.AppliedDefense.com

  35. Current Acq Data Deliveries • Always deliver a TLE and INP2 file set • INP2 near perigee (270 to 110 degrees true anomaly) every 1 second • INP2 for all other locations, every 5 sec • All Q/C against predicted ephemeris • TLE only valid when angle from the ground station between the predict ephemeris and the TLE is less than 0.2 degrees • INP2 must match with original ephemeris to within 0.2 degrees from the ground stations • Deliver IIRV to NASA when needed for NASA Ground Network contacts www.AppliedDefense.com

  36. TLE Generator Utility • Allow for easy generation of multiple TLEs from the same ephemeris file • Sets up satellite object with TLE for quality checking www.AppliedDefense.com

  37. TLE Quality Check Example • STK Chain “Angle Between” graph • TLE only valid:10 Apr 2009 23:00 to11 Apr 2009 06:30 UTC www.AppliedDefense.com

  38. INP2 Angle Generator Utility • Allow for easy generation of multiple INP2s • Sets up sensor objects for quality checking www.AppliedDefense.com

  39. INP2 Angle File Quality Check Example • Angle between ground station sensor boresight & satellite • Alaska INP2: 10 Apr 2009 23:00 to 11 Apr 2009 06:30 UTC www.AppliedDefense.com

  40. Example #1, Nominal Case www.AppliedDefense.com

  41. Example #2 (…Not Nominal) www.AppliedDefense.com

  42. Orbit Events Reports from STK • IBEX Crossing Times Report • At what time does each integer Re altitude occur? • Astrogator Stop & Continue for each Re integer • Astrogator Summary Report • Convert to txt format • Needed for scheduling contact times and attitude/ Sun repointing maneuvers • IBEX Apogee & Perigee Times Report • At what time does IBEX go through Apogee & Perigee? • STK satellite Apogee and Perigee Times custom report • Needed for scheduling contacts and science www.AppliedDefense.com

  43. Tracking Schedule Variations • Varies uniquely for each orbit • Based on both the visibility times and when the ground stations are available • If contacts were simply not possible near perigee, the orbit uncertainty will increase dramatically • Antenna nulls www.AppliedDefense.com

  44. Additional Reporting from STK • View Periods • Star Tracker Outages www.AppliedDefense.com

  45. Long-Term Analysis • Come to Toronto in August! www.AppliedDefense.com

  46. Where is FDG? • The FDG configuration is mobile (Thanks Jason)! • Besides the ADS MOR and Orbital MOC: • Southwest airlines flight #2892 on March 18 2009 • “Superprom 16”, Baldwin MD • Red Sky Grill/Hooters, Laurel MD • Point Mugu CA (NAVSOC) • My parents’ house, Baltimore MD • Mountain View CA (NASA Ames) • BWI Airport • Spaceflight Mechanics Meeting 2009, Savannah GA • Greene Turtle, Laurel MD • Las Vegas Airport • Game Sports Bar, Fulton MD • Many many hotels!!!! www.AppliedDefense.com

More Related