Courtesy of the Jonathan Space Report at http://www.planet4589.org/jsr.html, Jonathan McDowell is reporting that the Fengyun 1C satellite (1999-025A) was in an orbit of 862 x 843 km inclined 98.7 degrees prior to the ASAT intercept on January 11, 2007. And based on the post intercept debris orbital data he is reporting, "a wide range of heights indicating an energetic fragmentation with delta-Vs of -190 to +550 m/s. Of course, we are missing the tail of dV significantly less than -190 since those objects would reenter immediately."As of 1430 UTC this morning, the catalogued piece I saw in the lowest orbit was 1999-025E in a 746 x 167 km orbit inclined at 99.443 degrees. The debris piece in the highest orbit was 1999-025AM in a 3499 x 845 km orbit inclined at 100.158 degrees.
A quick check of my database shows the biggest threat from this debris field at this point is to the polar orbiting, sun-synchronous DoD DMSP weather satellites. These satellites are basically in the same orbit height and inclination (850 x 840 km inclined 98.8 degrees) as some of the debris from the Fengyun 1C. I should also note that our KH-12 photo imaging satellites in both the east and west planes could have a very small threat of collision.
Current sat track prediction runs of the known debris and the few satellites in the vicinity which we have info on show no immediate danger of collision. But if reports by CNN and other agency are accurate, we may have a much larger number of objects in this debris field that have not been catalogued yet.
The CNN story estimated the debris field at 40,000 pieces, which seems a bit excessive. If there are that many objects from this event, then the NORAD space catalog will more than double in size and they will be passing out the Excedrin in the granite mountain for some time to come. But based on everything I have seen so far, I am not convinced we are dealing with as many objects as CNN is quoting in their report.
I might add that there has been one instance of a collision in this portion of orbital space. On January 17, 2005, at 0214 UTC, there was a collision between a DMSP 5B F5 rocket body (Thor-Burner 2A final stage) 1974-015B/07219 (885 x 775 km, 99.1 deg inclination)
and debris from a Chinese CZ-4 third stage 1999-057CV/26207 (895 x 700 km, 98.2 deg inclination). The CZ-4 debris was created during an explosion on 11 March 2000. Orbit at the time of this collision was 895 x 700 km.
There were more than 300 objects cataloged from the CZ-4 propellant-induced breakup. As of 17 Jan 2005 there was a total of 176 pieces remaining in orbit. This collision created two new pieces of debris from the DMSP rocket body according to the Orbital Debris Progam Office at the Johnson Space Center.
So it looks like this retrograde orbital area already has quite a few objects from a previous encouter.
