Roughly estimated Progress 59 decay time

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Tue, 28 Apr 2015 12:08:53 -0400
The following *rough* estimates are based on early TLEs and my estimate of the area to mass ratio of a Progress
spacecraft.

Assumptions:

1. A/m = 0.0025 m^2/kg (Progress s/c)
2. Cd = 2.4
3. current space weather

USSTRATCOM has issued orbital elements of two objects from the 2015-024 launch. Normally the "A" object is the payload
and "B" is the rocket body, but the identities assigned to initial TLEs are not always correct; therefore, I have
propagated both orbits to decay, using the above Progress ballistic co-efficient.

For 2015-024A / 40619, GMAT 2014a propagates the epoch 15118.31986774 TLE to decay on 2015 Apr 29 near 08:47 UTC.

For 2015-024B / 40620, GMAT 2014a propagates the epoch 15118.53743509 TLE to decay on 2015 Apr 29 near 07:05 UTC.

The time of decay is especially sensitive to the perigee height, which could be revised in later TLEs. The above
estimates could easily be off by several hours or more.

Ted Molczan


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Received on Tue Apr 28 2015 - 11:09:47 UTC

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