National Aeronautics and Space Administration
Analysis and Consequences of the Iridium 33- Cosmos 2251 Collision
Phillip Anz-Meador1 and J.-C. Liou2 1 ESCG Jacobs, Houston, Texas, USA 2 NASA Johnson Space Center, Houston, Texas, USA National Aeronautics and Space Administration Outline • The spacecraft • Circumstances of the collision event • Physical characterization of the debris clouds – Characteristic size, mass, and area-to-mass (A/m) – Directionality and ∆v distributions – Momentum transfer • Comparisons with the NASA Standard Breakup Model • Long-term evolution of the debris clouds • Conclusions
2/17 National Aeronautics and Space Administration The Spacecraft I Cosmos 2251 • The Strela-2M series utilized the versatile NPO-PM KAUR-1 standard bus (Kosmicheskiy Apparat Unversalnogo Ryada-1, (Космический Аппарат Универсального Ряда), which can be translated as Spacecraft Bus from the Standardized Line (Group)-1). In addition to the LEO communication constellation Strela-2/-2M, the KAUR-1 bus has served as the basis for navigation (Tsiklon/Parus military series and Tsikada civil series and Nadezhda civil COSPAS/SARSAT subseries), geodesy (Sfera and GEO- IK/Musson), and science (Ionosfernaya, Cosmos 381 ionospheric topside sounder) spacecraft. • Background: family album of spacecraft using the KAUR-1 bus; middle inset: cross section of a Nadezhda spacecraft*; top inset: a Strela-2M spacecraft**
* after Russian Space News, issue 24 (1994), p. 24 ** FROM: http://www.astronautix.com/craft/strela2m.htm
3/17 National Aeronautics and Space Administration The Spacecraft II Iridium 33
•The Iridium first-generation constellation utilized the Lockheed-Martin LM700A bus, shown in exploded view (left) and with Iridium nadir payload module (above) From: Rudiger et al., Application of Existing Satellites to Space and Earth Science Missions, 1997.
4/17 National Aeronautics and Space Administration The Spacecraft III physical & operational characteristics
Cosmos 2251 Iridium 33 bus KAUR-1 LM700A dry mass [kg] 900 (estimated) 556 Shape Cylinder with boom Triangular prism with panels
Stabilization Gravity gradient 3 axis Size 2 m x 2 m (body) 3.6 m long onboard energy Core cylinder may Hydrazine tanks
sources have been for thrusters; NiH2 pressurized battery Initial orbit 800x776 km, 74° 779x776 km, 86.4° inclination inclination status derelict operational
5/17 National Aeronautics and Space Administration The collision event Estimated collision parameters:
Event time: 10 February 2009, 16h 55m 59.8s GMT Location: 72.50° N latitude 97.86° E longitude 778.6 km altitude Relative velocity: 11.647 km/s Directionality: from the viewpoint of the Iridium 33 spacecraft, Cosmos 2251 approached at an elevation of -2.6° and an azimuth (measured from North) of 231° Orbital distribution: see Gabbard charts on next 2 pp.
6/17 National Aeronautics and Space Administration Cosmos 2251 Gabbard diagram
1800 C2251 apogee series, June 2010 1600 C2251 perigee series, June 2010
1400 C2251 apogee srs, June 2009
C2251 perigee srs, June 2009 1200
1000
altitude km] 800
600
400
200
0 85 95 105 115 period [min]
7/17 National Aeronautics and Space Administration Iridium 33 Gabbard diagram
1800
Iri33 apogee srs, June 2010 1600 Iri33 perigee srs, June 2010 1400 Iri33 apogee srs, June 2009 1200 Iri33 perigee srs, June 2009
1000
800 altitude [km]
600
400
200
0 85 90 95 100 105 110 115 period [min]
8/17 National Aeronautics and Space Administration Physical characterization of the debris clouds I characteristic size distribution Size Distributions of Iridium 33, Cosmos 2251, and FY-1C Fragments 10000
FY-1C
Iridium 33 1000 Cosmos 2251
100 Cumulative Number Cumulative
10
1 0.01 0.1 1 10 Diameter (m)
9/17 National Aeronautics and Space Administration Physical characterization of the debris clouds II mass distribution
10000 Cosmos 2251
] Iridium 33 1000 power law fit, C2251 power law fit, Iri33
100
“step” indicative of 10 objects with no size cumulative number [ - [ number cumulative (RCS) data
1 0.0001 0.001 0.01 0.1 1 10 100 1000 mass [kg] Masses estimated using median A/m and characteristic lengths; power law slope is -1.2, considerably steeper than standard breakup model.
10/17 National Aeronautics and Space Administration
A/M Distribution of Iridium 33 Fragments (1/2)
A/M Distribution of Iridirm 33 Fragments 120
NASA Breakup Model Prediction 100 TLE Data (17 May 2010)
80
60 Number
40
20
0 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
2 Log10(A/M m /kg)
11/17 National Aeronautics and Space Administration
A/M Distribution of Iridium 33 Fragments (2/2)
A/M Distribution of Iridirm 33 Fragments 120
NASA Breakup Model Prediction 100 TLE Data, A/M/3 (17 May 2010)
80
60 Number
40
20
0 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
2 Log10(A/M m /kg)
12/17 National Aeronautics and Space Administration
A/M Distribution of Cosmos 2251 Fragments
A/M Distribution of Cosmos 2251 Fragments 0.25
NASA Breakup Model Prediction
0.2 TLE Data (17 May 2010)
0.15
0.1 Number (Normalized)
0.05
0 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
2 Log10(A/M m /kg)
13/17 National Aeronautics and Space Administration
Comparison of the Two Fragment Clouds
14/17 National Aeronautics and Space Administration
Physical characterization of the debris clouds IV • SSN Catalog data analysis ∆v and directionality distributions have been estimated for both clouds, but are currently under review – Little or no momentum transfer observed in cataloged clouds • Haystack/HAX data analysis – Both clouds were observed by the Haystack and Haystack Auxiliary (HAX) radars shortly after the event – Analysis ongoing
15/17 National Aeronautics and Space Administration
Long-term evolution of the debris clouds
Percent of Cosmos 2251/Iridium 33 Collision Fragments Still in Earth Orbit as a Function of Calendar Year 100
90 % of Cosmos 2251 fragments 80 % of Iridium 33 fragments 70
60
50
40
30 Percent of Objects Still in Orbit
20
10
0 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 2060 2065 2070 2075 2080 2085 2090 2095 2100 2105 2110
Year
16/17 National Aeronautics and Space Administration
Conclusions
• A very large, very energetic event: – C2251: 1267 fragments cataloged; 1212 on orbit as of 10 June 2010 SSN catalog – Iri33: 521 fragments cataloged, of which 498 are on orbit – History indicates that cataloging may continue for some time – Impact velocity highest of known intentional & accidental collisions • These debris clouds will influence the LEO environment for decades to come • Significant work remains to be done to understand origin of A/m distribution (Iri33), mass and size distributions in context of the NASA standard breakup model
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