Space Surveillance Contributions to the STS 107 Accident Investigation A Presentation to the AAS/AAIA Space Flight Mechanics Conference 8-12 February 2004

Space Surveillance Space Surveillance Contributions to the Contributions to the

STS 107 Accident STS 107 Accident InvestigationInvestigation

A Presentation to the AAS/AAIA

Space Flight Mechanics Conference

8-12 February 2004

R. Morris, HQ AFSPC/XPY

214th AAS/AIAA Space Flight Mechanics Conference, 2003 February 9

AuthorsAuthors

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

1st Space Control Squadron R.G. Thurston


OverviewOverview

Analysis Contributions Satellite Breakup Debris Campaign Flight Day 2 Piece Flight Day 5 Object

Summary


Satellite BreakupSatellite 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 phase—no close approaches less than 1,000km




Debris CampaignDebris Campaign


Debris CampaignDebris 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)


Flight Day 2 PieceFlight Day 2 Piece


FD2 PieceFD2 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 orbit—none found


FD2 Piece (cont)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


FD2 Piece: Event TimelineFD2 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


Shuttle Orbit

Piece

-1400

-1200

-1000

-800

-600

-400

-200

0

200

17-00:00:00 18-00:00:00 19-00:00:00 20-00:00:00 21-00:00:00

GMT (DAY-HH:MM:SS)

DE

LTA

TIM

E (

SE

CO

ND

S)

.

BEALE

CAPE COD

EGLIN

NAV

SHUTTLE

FD2 Piece: Separation from ShuttleFD2 Piece: Separation from Shuttle

Piece Separation

Track grouping shows CONUS overflights


FD2 Piece: CharacteristicsFD2 Piece: Characteristics

Ballistic coefficient (B = (Drag Coefficient * Area)/Mass) near 0.10 m2/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


FD2 Piece: RCS DataFD2 Piece: RCS Data

Cape Cod Track on 17 Jan, 1857Z

0 10 20 30 40 50 60 70

Seconds

RC

S


0 5 10 15 20 25 30

Seconds

RC

S


0 5 10 15 20 25 30

Seconds

RC

S

17 Jan – slow rotation

18 Jan – 7 sec rotation period19 Jan – 3 sec rotation period

RCS varied from ~0.1 to ~0.7 m2


FD2 Piece: Separation 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


FD2 Piece: Continued AnalysisFD2 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


FD2 Piece: Object Types Examined 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

NASA photo


FD2 Piece: ConclusionsFD2 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 data—along with many other data sources—to formulate final conclusions and report


Flight Day 5 ObjectFlight Day 5 Object


FD5 Object: BackgroundFD5 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)


FD5 Object: COMBO ResultsFD5 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


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 orbit—no possible conjunction with Columbia

FD5 Object: SummaryFD5 Object: Summary

TOP 5 COMBO CANDIDATES


Side View 2

Overhead View - Distant Overhead View - Close

Columbia --> OrbComm OrbComm --> Columbia

Side View 1

Video Animations:

FD5 Object: COMBO VisualizationFD5 Object: COMBO Visualization

Trailing Perspective Top-Down Perspective

Shuttle from ORBCOMM


SummarySummary


SummarySummary

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 NASA’s final determination of the cause of the accident

Documents

Space Surveillance Contributions to the STS 107 Accident Investigation A Presentation to the AAS/AAIA Space Flight Mechanics Conference 8-12 February 2004