Hitomi: debris-shedding tracked by Eglin radar as it occurred?

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Fri, 1 Apr 2016 13:23:53 -0400
In an effort to learn more about the debris-shedding event associated with the change of orbit of Hitomi (16012A /
41337), I have computed conjunctions between what appears to be its last known pre-event orbit - that of the epoch
16085.39655986 TLE - and the subsequent 16 clearly post-event TLEs. I found that conjunction times ranged between 2016
Mar 26 00:52:44 UTC and 02:48:50 UTC. Six fell within the approximate time of the debris-shedding event reported by
JSpOC: 01:42 UTC +/- 11 min. The wide range of the times is due to the sensitivity to small errors in the orbital
elements, especially in mean motion and rate of decay, but also the eccentricity and argument of perigee.

In the course of the analysis, I noticed that the approximate time of the event reported by JSpOC coincides with a pass
within range of USSTRATCOM's radar tracking site at Eglin AFB. 


Hitomi was above 2 deg elevation between 01:38:51 UTC and 01:50:24 UTC, which falls within the 22 min. time range of the
debris event reported by JSpOC. 

Hitomi culminated at 01:44:37 UTC, 34 deg above the SSE horizon of Eglin. At that time, the separation between the
pre-event TLE and the post-event TLEs ranged between 1 km and 14.3 km. Mean was 4.8 km; median 3.8 km. Based on this and
the range of conjunction times, it seems possible that Eglin may have captured the event in progress. I asked Dr. T.S.
Kelso whether a record by Eglin of the debris-shedding event in progress, could yield any more useful data for the
investigation of the incident than otherwise? He responded as follows:

"I believe that if the HITOMI debris event occurred when JSpOC reported that it is highly likely that Eglin was tracking
it when it happened. If that's the case, we should have very good data which could be of great value to the HITOMI team
in their efforts to figure out what might have happened to their satellite and how best to recover it."

Ted Molczan

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Received on Fri Apr 01 2016 - 12:24:47 UTC

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