1. Space Surveillance Contributions to the STS 107 Accident Investigation A Presentation to the AAS/AAIA Space Flight Mechanics Conference 8-12 February 2004 R. Morris, HQ AFSPC/XPY

2. 2 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Authors HQ AFSPC Space Analysis Division T.S. Kelso, Col USAF retired (now with Analytical Graphics, Inc.) R.F. Morris, G.T. DeVere, J.C. Randolph, B.R. Bowman, R.A. Racca, N.L. Ericson 1 st Space Control Squadron R.G. Thurston

3. 3 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Overview Analysis Contributions Satellite Breakup Debris Campaign Flight Day 2 Piece Flight Day 5 Object Summary

4. 4 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Satellite Breakup

5. 5 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Satellite Breakup NASA requested details of satellite breakup on 29 Jan Processed data on satellite breakup during STS 107 mission to help NASA determine risk of impact to Columbia Russian COSMOS 1849 (1987-048A) source of breakup 62º inclination, apogee height 7,439km, perigee height 94km Recovered and processed all SSN debris observations Used specialized in-house processing algorithms & software Generated element sets for 51 debris objects Analysis showed breakup debris not close to Columbia 39º inclination, apogee height 280km, perigee height 263km Out of phaseno close approaches less than 1,000km

6. 6 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Satellite Breakup

7. 7 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Debris Campaign

8. 8 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Debris Campaign NASA requested analysis of data collected during Inter- Agency Space Debris Coordination Committee (IADC) Debris Campaign for close approaches to STS 107 Supported 2003 IADC Debris Campaign on 20 Jan 2003 using Cobra Dane (L-band radar) at high power Collected added data on objects not in satellite catalog Processed several thousand metric observations Generated over 900 new element sets No debris assessed to present serious collision threat Only 9 objects had orbits crossing STS 107 orbit regime None were found to have close approaches (out of phase)

9. 9 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Flight Day 2 Piece

10. 10 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD2 Piece Worked with 1 SPCS to discover unexpected piece had separated from Columbia on Flight Day 2 (FD2, 17 Jan 2003) Sensors and 1 SPCS did not process piece in real time Common practice to use NASA vectors exclusively Eliminated need for manual scrutiny by sensor operators Limited sensor data–few tracks initially sent to Space Control Center Cape Cod and Eglin down on parts of 17 Jan Post-processing discovered a small object in shuttle orbit High interest in the FD2 piece by NASA, CAIB, and DCIST Searched for additional objects in shuttle orbitnone found

11. 11 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD2 Piece (cont) Used SSN data to form initial orbit on FD2 piece Determined that orbit was very similar to shuttle No other satellites or objects in similar orbit 39º inclination, 90-minute period Collected data from additional sensor tracks Requested sites to recover any/all data on FD2 piece Obtained data during sensor downtimes Obtained data below normal thresholds Extensive work done to recover & process raw radar data

12. 12 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD2 Piece: Event Timeline 17 Jan, 1442Z: Shuttle attitude reoriented Moved from tail-first to right wing-first orientation 17 Jan, 1517Z: Shuttle attitude reoriented Returned to tail-first orientation 17 Jan, 1500Z-1615Z: Piece separates 17 Jan, 1857Z: First confirmed SSN sensor track 19 Jan, 2146Z: Last confirmed SSN sensor track 20 Jan, 0145Z-0445Z: Piece decayed from orbit

13. 13 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Shuttle Orbit Piece FD2 Piece: Separation from Shuttle Piece Separation Track grouping shows CONUS overflights

14. 14 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD2 Piece: Characteristics Ballistic coefficient (B = (Drag Coefficient * Area)/Mass) near 0.10 m 2 /kg Suggests a relatively lightweight piece Physical size of piece estimated to be ~0.4m by ~0.3m Object was non-spherical Wavelength of UHF radars (0.7m) is very close to piece size Introduces uncertainty in size assessment Piece was initially semi-stable or in a slow rotation on 17 Jan Approximately 24 hours later, piece was in a tumble

15. 15 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD2 Piece: RCS Data 17 Jan – slow rotation 18 Jan – 7 sec rotation period 19 Jan – 3 sec rotation period RCS varied from ~0.1 to ~0.7 m 2

16. 16 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD2 Piece: Separation Generated best possible orbit on piece using high- accuracy special perturbation (SP) theory and SSN observations Determined separation time/velocity using COMBO (Computation Of Miss Distance Between Orbits) Separation time window between 1500Z and 1615Z Results favor 1530Z–1600Z timeframe as most likely Separation velocity was between 0 and 1.5 m/s Low separation velocity makes exact separation direction and time more uncertain Results favor ~0.3 m/sec

17. 17 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD2 Piece: Continued Analysis Initial results on FD2 piece generated much interest at NASA, CAIB, and DCIST Further analysis performed to determine if FD2 piece was from the left wing and possibly associated with the accident Examined many candidate pieces from the shuttle to understand their area/mass ballistic characteristics Compared candidate B terms with that generated on FD2 piece from SSN data AFRL was involved to conduct radar tests of candidates Compared candidate radar cross sections with SSN data

18. 18 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD2 Piece: Object Types Examined Items from inside Shuttle Bay Thermal Blankets (beta cloth) Thermal Blankets (aluminized) Beta Cloth, logo panels Items from exterior of Shuttle Thermal Blankets (FRSI, AFRSI) Heat Tiles (HRSI) Items from Shuttle wing RCC panel (wing leading edge) Ear muff (space under RCC panel) Carrier panel + Horse Collar seal (surface of wing, behind leading edge) RCC T-seal (wing leading edge) RCC segment (wing leading edge) NASA photo

19. 19 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD2 Piece: Conclusions FD2 Piece: Conclusions SSN Area/Mass Analysis integrated with AFRL RCS test data (candidate must pass both tests) RCS testing further narrowed candidate list RCC panel fragment is leading candidate for FD2 piece Damage to Reinforced Carbon-Carbon (RCC) wing leading edge panel would almost certainly result in wing burn- through during reentry FD2 piece probably associated with left wing problems CAIB used dataalong with many other data sources to formulate final conclusions and report

20. 20 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Flight Day 5 Object

21. 21 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD5 Object: Background Review of NASA log entries prompted request Flight Day 5 (21 Jan) at 08:51:30Z, crew saw a bright object that seems to be moving with them… at a long distance. JSC-DM submitted request for a COMBO analysis COMBO: Computation Of Miss Distance Between Orbits Identify all objects within a NASA specified box around Columbia Compute miss-distances Time period of analysis: 08:39Z to 08:54Z (16-minute span)

22. 22 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 FD5 Object: COMBO Results Performed COMBO Analysis Used the complete elset catalog to identify all candidate objects 250+ objects identified within box during specified time interval Minimum miss distance for all objects: ~370 km (Cerise debris) More than 75% were in box for less than 5 minutes Only 6 objects were in box for 10 minutes or greater 5 candidates identified based on: Object size Visibility from Columbia (accounting for shuttle attitude) Illumination angles (beta angle) Orbit trajectory Length of time in specified box

23. 23 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Most likely candidate is the ORBCOMM satellite Paralleled shuttle trajectory for duration of time interval Visible from overhead windows in crew cabin Bright reflection likely: Two 42 solar arrays that follow the sun Optimal beta angle at ~08:42Z (43°) Stable satellite attitude (steady light source) Higher orbitno possible conjunction with Columbia FD5 Object: Summary TOP 5 COMBO CANDIDATES

24. 24 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Video Animations: FD5 Object: COMBO Visualization Trailing PerspectiveTop-Down Perspective Shuttle from ORBCOMM

25. 25 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Summary

26. 26 14th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9 Summary Conducted various analyses: COSMOS 1849 breakup IADC 24-hour Debris Campaign Flight Day 2 Piece Flight Day 5 Object Observed by STS 107 Crew Contributed to NASAs final determination of the cause of the accident