The Characteristics and Consequences of the Break-up of the Fengyun-1C Spacecraft

Transcription

1 The Characteristics and Consequences of the Break-up of the Fengyun-1C Spacecraft N. Johnson, E. Stansbery, J.-C. Liou, M. Horstman, C. Stokely, D. Whitlock NASA Orbital Debris Program Office NASA Johnson Space Center 58 th International Astronautical Congress September 2007

2 Outline Background of Breakup Event Debris Cloud Characterization U.S. Space Surveillance Network data Special Haystack radar observations Changes in the near-earth Environment Near- and Long-term Collision Effects Conclusions 2 58 th International Astronautical Congress

3 Breakup Event Summary The Fengyun-1C spacecraft ( A, U.S. Satellite Number 25730) was the target on 11 January 2007 of a ground-launched, direct ascent ballistic missile equipped with a kinetic kill vehicle. Fengyun-1C orbit: ~ 850 km, 98.6 deg inclination Fengyun-1C mass: ~960 kg Impact velocity: ~ 9 km/s 3 58 th International Astronautical Congress

4 SSN Observations of Debris Cloud Six months after the breakup, a total of 1967 pieces of debris had been officially cataloged by the U.S. Space Surveillance Network. ~ 400 additional debris were being tracked but not yet cataloged Apogee Perigee 11 July 2007 Orbital Period of Parent Altitude (km) Slight posigrade asymmetry (60/40) in the heart of the cloud Period (min) 4 58 th International Astronautical Congress

5 SSN Observations of Debris Cloud (continued) A greater asymmetry is seen in the debris inclinations; approximately 80% of the debris have inclinations greater than those of Fengyun-1C prior to the intercept Inclination (deg) Period (min) 5 58 th International Astronautical Congress

6 SSN Observations of Debris Cloud (continued) Preliminary analysis of 1600 debris indicates area-to-mass ratios on average greater than predicted by the NASA standard breakup model for a hypervelocity collision. Verification of conversation from RCS to characteristic length is continuing. 1.E+02 1.E+01 1.E+00 A/M (m 2 /kg) 1.E-01 1.E-02 1.E Characteristic Length (m) 6 58 th International Astronautical Congress

7 Haystack Observations of Debris Cloud The Haystack radar observed the debris cloud for 1.9 hours in a special orbit plane tracking mode ~24 hours after the breakup. Some sub-centimeter debris were observed Count Altitude (km) Characteristic Length (m) GMT Time of Day (hrs) 7 58 th International Astronautical Congress

8 Haystack Observations of Debris Cloud (continued) During January through May, Haystack observed the debris in a normal staring mode for 184 hours Approximate time of parent orbit plane crossing Inclination (deg) Haystack not operated during this time window GMT Time of Day (hrs) 8 58 th International Astronautical Congress

9 Changes in the near-earth Environment The number of tracked objects in LEO increased ~ one-third as a result of the breakup of Fengyun-1C. The debris now represents a significant portion of conjunction assessments for many operational spacecraft. A least two U.S. spacecraft have maneuvered to avoid very close approaches of tracked debris, and the ISS canceled a planned collision avoidance maneuver when the estimated miss distance increased to an acceptable value shortly before the conjunction Effective Number of Objects per 50 km Bin Tracked objects (1 June, 2007) Tracked objects (1 January, 2007) Fengyun-1C fragments Altitude (km) 9 58 th International Astronautical Congress

10 Evolution of Debris Orbit Planes th International Astronautical Congress

11 Projected Debris Decay Rate Due to the apparent higher than expected debris area-to-mass ratios, the orbital decay rates will likewise be accelerated. However, the greater than expected number of large debris yields a lifetime large debris collision risk for the cloud of essentially the same magnitude. For smaller debris collision risks may be greater than model predictions. 100 Percent of Debris Cloud Remaining in Orbit Projected decay based upon standard model Projected decay based upon preliminary observations Years since the Event th International Astronautical Congress

12 Long-term Effects on the Environment NASA s evolutionary satellite population model LEGEND was employed to predict the possible increase in the long-term large object population resulting from the Fengyun-1C debris cloud Effective Number of Objects (>10 cm) in LEO With Chinese ASAT debris Without Chinese ASAT debris th International Astronautical Congress

13 Summary The breakup of Fengyun-1C stands as the most severe satellite fragmentation of the space age, and its detrimental effects will be very longlasting. In analyses to date, the number of debris greater than 10 cm produced appears to markedly exceed the number predicted by the NASA standard breakup model for hypervelocity collisions. An assessment of the number of actual debris 1 cm and larger is still underway. Both the IADC Space Debris Mitigation Guidelines and the UN COPUOS Space Debris Mitigation Guidelines explicitly recommend the avoidance of any intentional destruction which would result in long-lived debris. The test involving Fengyun-1C is non-compliant with those recommendations th International Astronautical Congress