Dissecting Space Debris Events Dr. T.S. Kelso

Overview Three notable events Recognizing event triggers IRIDIUM 47, 2014 Sep 26 IRIDIUM 91, 2014 Dec 3 DMSP 5D-2 F13, 2015 Feb 25 Recognizing event triggers Performing orbital forensics Conclusions

Event Trigger TLEs released via Space Track Typically not added to their SATCAT for days/weeks No event time or cause provided Only identifies International Designator (launch) 1 40248U 97082H 14261.40478706 .00020115 00000-0 70980-2 0 13 2 40248 85.8794 309.1223 0091517 88.3200 272.8474 14.32278588 18 Data posted to CelesTrak within 8 hours Perform initial analysis and tweet results (@TSKelso) Goal to provide awareness and starting point for other analysts

Post-Trigger Analysis Obtain TLEs for all objects Check debris for nodal drift & alignment with pre- existing objects Refine event time by plotting range to parent Generate relative velocity using STK Viewer Provides insight into type of event Can be limited by data quality and number of pieces

IRIDIUM 47 Event First public TLEs: 2014 Sep 26 10 TLEs for 1997-082

Debris aligned with IRIDIUM 47 and 49 Separation of debris planes correlated to time since event

Separation of debris planes, 2014 Mar 24 to Sep 25 Suggests event occurred around 2014 Jun 12

Separation of debris planes, 2014 Jun 5-18 Suggests event occurred around 2014 Jun 12

Debris range to IRIDIUM 47, 2014 Jun 5-19 Suggests event occurred around 2014 Jun 12

Debris range to IRIDIUM 47, 2014 Jun 11-14 Suggests event occurred on 2014 Jun 12

Debris range to IRIDIUM 47, 2014 Jun 12 Suggests event occurred around 1900 UTC

IRIDIUM 47 Results TLE analysis suggests event time of 2014 Jun 12 around 1900 UTC JSpOC-reported event time 2014 Jun 7, 0330 UTC Shows limitations of TLE data for long propagation No public statement from Iridium regarding event Only stated IRIDIUM 47 still operational Optical observations confirm stable attitude

Separation of debris planes from IRIDIUM 47, 2014 Jun 5-15 No clear event time apparent

IRIDIUM 47 and debris at JSpOC-predicted event time

IRIDIUM 91 Event First public TLEs: 2014 Dec 3 4 TLEs for 2002-005

2002-005 orbits and debris at TLE release Clear alignment with IRIDIUM 91 & 95

Debris range to IRIDIUM 91, 2014 Nov 28-Dec 3 Suggests event occurred on Nov 30

Debris range to IRIDIUM 91, 2014 Nov 30 Suggests event occurred on Nov 30 @ 1615 UTC

IRIDIUM 91 and debris at predicted event time

IRIDIUM 91 Results TLE analysis suggests event time of 2014 Nov 30 @ 1615UTC JSpOC-reported event time agrees No public statement from Iridium regarding event Only stated IRIDIUM 91 still operational Optical observations confirm stable attitude IRIDIUM 91 was the spare moved into IRIDIUM 33’s slot after the collision with COSMOS 2251 on 2009 Feb 10

DMSP 5D-2 F13 Event First public TLEs: 2015 Feb 25 26 TLEs initially (eventually 160 objects)

1995-015 orbits and debris at TLE release Debris does not line up with known orbits

Separation of debris planes, 2015 Jan 24-Feb 26 Suggests event occurred around 2015 Feb 1

Separation of debris planes, 2015 Jan 29-Feb 5 Suggests event occurred around 2015 Feb 1

Debris range to DMSP 5D-2 F13, 2015 Jan 30-Feb 5 Suggests event occurred on 2015 Feb 3

Debris range to DMSP 5D-2 F13, 2015 Feb 3 Suggests event occurred on 2015 Feb 3 @ 1723 UTC

DMSP 5D-2 F13 and debris at predicted event time

Gabbard plot of all 160 pieces of debris Ranges from perigee of 350 km to apogee of 1,200 km

Relative Velocity of Debris Use to further illuminate event circumstances Start with all 160 debris objects Propagate to event time and filter to within 100 km Eliminates all but 52 objects Calculate velocity of each debris piece relative to pre- event orbit of main payload

Distribution of 52 pieces of debris within 100 km

Relative velocity distribution in satellite frame

Largest components vertical and in velocity direction

DMSP 5D-2 F13 Results Analysis showed event time of 2015 Feb 3 @ ~1723 UTC 50th Space Wing Review Board stated: “Post event analysis indicated that a major kinetic event occurred at ~1720z.” Attributed cause to Battery 1 rupture Thermal runaway detected on pass prior to kinetic event at 1634 UTC Successfully safed and decommissioned satellite

Conclusions No events attributed to collisions All events occurred in high-density debris convergence zones near the poles Analysis hampered by delayed release of orbital data and lack of transparency Some suggestions this may be improving Cases represent opportunities to improve safety of flight Probably won’t be the last examples

Polar debris convergence zones Correlated to inclination of large constellations

Polar debris convergence zones Correlated to inclination of large constellations

Questions?