1. NASA Johnson Space Center Orbital Debris Program Office Accidental Collision of DMSP R/B and Chinese Debris on 17 January 2005 7 February 2005 Summary

2. NASA Johnson Space Center Orbital Debris Program Office 2 Executive Summary The second known accidental collision between two Earth satellites from different missions occurred on 17 January 2005, involving a 1974 US rocket body and debris from a Chinese rocket body which exploded in March 2000. Both objects were in similar retrograde orbits. The collision occurred at an altitude of 885 km. Only two debris from the US rocket body had been detected within three weeks of the event. The only other known accidental collision between two Earth satellites from different missions occurred on 24 July 1996, involving the 1995 French CERISE spacecraft and debris from a French rocket body which exploded in November 1986.

3. NASA Johnson Space Center Orbital Debris Program Office 3 Collision Summary Time and Location of Collision: 0214 GMT, 17 January 2005 80.6 S, 306.8 E Altitude of Collision:885 km Satellites Involved in Collision:US DMSP 5B F5 R/B (Thor-Burner 2A final stage) Sat. No. 07219, Int. Designator 1974-015B Launched 16 March 1974 Orbit at time of collision: 775 km by 885 km Chinese CZ-4 Third Stage Debris Sat. No. 26207, Int. Designator 1999-057CV Created during Explosion on 11 March 2000 Orbit at time of collision: 700 km by 895 km New Debris Created:Two pieces from DMSP R/B tracked (Sat. No.s 81057 and 87876)

4. NASA Johnson Space Center Orbital Debris Program Office 4 Location of Collision Groundtracks +/- 30 minutes of 0214 GMT, 17 January 2005 DMSP R/B CZ-4 Debris

5. NASA Johnson Space Center Orbital Debris Program Office 5 Location of Collision, Alternate View DMSP R/B CZ-4 Debris 775 km by 885 km 99.1 deg inclination 700 km by 895 km 98.2 deg inclination Collision Altitude: 885 km

6. NASA Johnson Space Center Orbital Debris Program Office 6 Colliding Objects plus 2 Debris Graphic by AFSPC/1SPCS

7. NASA Johnson Space Center Orbital Debris Program Office 7 New Debris from DMSP R/B Graphic by AFSPC/1SPCS

8. NASA Johnson Space Center Orbital Debris Program Office 8 Perturbation of CZ-4 Debris Orbit Graphic by AFSPC/1SPCS

9. NASA Johnson Space Center Orbital Debris Program Office 9 Breakup of CZ-4 in March 2000 (1999-057C, Sat. No. 25942) CZ-4 third stage suffered a post-mission, propellant-induced breakup on 11 March 2000. More than 300 debris were officially cataloged. A total of 176 cataloged debris remained in orbit on 17 January 2005.