Progress 59 decay estimate

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Mon, 4 May 2015 19:43:52 -0400
Using the numerical integrator in GMAT 2014a, I found that Cd=2.2 and A/m=0.00259 m^2/kg are sufficient to account for
the decay over the span of USSTRATCOM's TLEs of epoch 15122.85272294 and 15124.87998146. 

Allowing the propagation to continue until decay, results in impact (10 km altitude) on 2015 May 08 near 21:03 UTC. The
uncertainty is 19 h, based on the rule of thumb of 20 percent of the estimated time remaining to decay, measured from
the epoch of the latter of the two TLEs.

The estimated time to decay has been trending earlier each day, mainly due to an increase in the 10.7 cm solar flux.

I converted the epoch 15122.85272294 TLE for propagation by GMAT using TLE Analyzer 2.12. I configured GMAT to use the
Dormand-Prince 78 numerical integrator, with the EGM-96 gravity model (degree 90, order 90), and the MSISE90 atmosphere
model. For the solar flux and geomagnetic index inputs required by MSISE, I used the daily mean values from May 02
through May 04 UTC.

Ted Molczan


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Received on Mon May 04 2015 - 18:44:42 UTC

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