Edward S Light asked: > Given the newly-released TLE for object 27713 = 03-003B, "STS > 107 debris", and the actual STS-107 TLEs, could anyone, e.g. > using COLA and/or its kin, determine when the two objects > were coincident? Short answer: Not in this case. Long answer: Based on comments from CAIB (Columbia Accident Investigation Board) members, the object was detected on 2003 Jan 17 by Eglin AFB, on the pass that culminated at 15:44 UTC. The same sources believe that the object came loose about an hour earlier, during one of the few attitude manoeuvres made by Columbia that day. Here is a Columbia elset appropriate for this analysis: 1 27647U 03003A 03017.58333333 .00054755 65718-5 11934-3 0 95 2 27647 39.0149 223.0048 0012360 355.7135 358.5111 15.97626761 143 The one that debris elset issued so far: 1 27713U 03003B 03018.89361124 .04158089 28060-1 63330-2 0 15 2 27713 39.0177 214.2209 0013015 7.8234 352.0943 16.06862990 17 suggests that the separation occurred a little after 17:30 UTC - nearly 2 hours after the first detection by Eglin, and about 3 hours after it is thought to have separated. I attribute this difference to the uncertainty in the rate of decay and/or limitations of the SGP4 model. The rate of decay was very high, and the epoch of the debris elset is more than one day after it separated, so even small uncertainties in the rate of decay will have a large effect on propagated position. Increasing the B* term by less than 2 percent to 0.64500e-2, is sufficient to place the time of separation about an hour before the Eglin pass, as expected. I doubt that the B* term is more accurate than 2 percent, especially when propagating over one day. Ted Molczan ----------------------------------------------------------------- To unsubscribe from SeeSat-L, send a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@satobs.org List archived at http://www.satobs.org/seesat/seesatindex.html
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