FW: USA 31 orbit?

Ted Molczan (molczan@fox.nstn.ca)
Mon, 29 Jul 1996 12:35:23 -0400

Phil Chien wrote the following in response
to Allen Thomson's question regarding the
orbital inclination of USA 31:

>My records indicate that the transtage (liquid bi-prop upper stage before
>the IUS entered operation) failed to ignite for its second burn, stranding
>the payload in a lower than planned orbit.


>What's interesting is an unclassified report from the Task Force for the
>NASA Advisory Council.  After the STS-49 fiasco the task force researched
>whether or not satellite rescues should be done in the future.  The "Report
>of the Group Task Force on Satellite Rescue and Repair" a/k/a The Covert
>report (29 September 1992) lists many satellites which could have
>potentially be rescued and salvaged by the shuttle.

>It lists the 1988 77A satellite as "VORTEX" and is my source for the
>reference on the Transtage failure.  What's interesting is that it lists
>the satellite as one which could have _potentially_ been rescued by the

>The report's fine print states "Please note that the determination of which
>satellites could be rescued by the Shuttle is based on the best estimates
>of the Group Task Force."  I have noticed several mistakes in the chart,
>including misidentification of some unclassified satellites, but overall
>it's a fairly accurate document, so I'm assuming that its identification of
>the classified satellites is correct until I get a more reliable source.
>(And media speculations and sound-byte artists don't count!)

I decided to consult Jonathan McDowell's compilation 
of debris orbits supplied by] various countries to 
the U.N., and low and behold it provides what seems to
me to be conclusive proof that USA 31 was not stranded 
in a 151 x 14103 km transfer orbit:

1988-77A  [USA 31]  99.8     151 x  14103 x  29.3  1C
1988-77B            99.8     151 x  14103 x  29.3  1D
1988-77C            99.8     151 x  14103 x  29.3  1D
1988-77D           708.9     465 x  39449 x  26.7  1D
1988-77E           707.7     461 x  39396 x  26.7  1D
1988-77F           669.6     385 x  37564 x  27.3  1D
1988-77G           718.8     830 x  39573 x  26.9  1D
1988-77H           718.8     830 x  39573 x  26.9  1D
1988-77J           718.8     830 x  39573 x  26.9  1D
1988-77K           718.8     830 x  39573 x  26.9  1D
1988-77L           718.8     830 x  39573 x  26.9  1D
1988-77M           717.7     807 x  39527 x  26.9  1D

The debris items, 88077D - M, clearly show that at 
least one more manoeuvre occurred, which changed the
apogee, perigee and the inclination. There would have
been one more manoeuvre to circularize the orbit and
reduce the inclination to zero. Although this proves
that the object was not stranded in the 151 x 14103 km
orbit, it does not prove that it reached its final
GEO destination.

So Phil's concerns about inaccuracies in the task force
report he cited were justified - another example of how 
difficult space sleuthing is. Fortunately, in this case
a reliable source of information could be found - that
is more the exception than the rule.

Finally, note that the orbital period of the objects
88077A-C are incorrect. McDowell has noted that many
such errors are present in the U.N. data.

Ted Molczan