re: USA 31 orbit?

Philip Chien (
Mon, 29 Jul 1996 09:18:59 -0400 (Allen Thomson) asks:
>   Is there any information available on the orbit, particularly
>the inclination (high or low), of the USA 31/1988-077 Titan 34D
>payload launched from Cape Canaveral on 2 September 1988?

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.  A couple of years after that I
was talking with Martin Marietta commercial Titan folks about the
reliability of the Titan, and they indicated that the Transtages which
failed were fairly old units (implying that they didn't have the best
technology available and were no longer in use, but not specifying which

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!)

If the VORTEX was intended for geosynchronous (or a near geo) orbit (as I
believe it was) then normal operation would be two Transtage burns - one
for the perigee burn to change the Titan parking orbit to GTO, and an
apogee burn several hours later to circularize the orbit at GEO altitude.

If this is the case, and if it's true that the second Transtage burn failed
then the satellite would have been left in an elliptical orbit (e.g. e >
.3) -- and clearly well beyond the shuttle's maximum rendezvous altitude
(about 311 nautical miles).

The only way I could see any potential shuttle rescue would be to burn all
of the spacecraft's maintenance propellant to reduce its orbit to a
shuttle-compatible orbit.  The problem with this theory is that it implies
an extremely large propellant load, and larger engines than would be
reasonable for a GEO satellite without a built-in apogee engine.

So we have an apparent contradiction ...  Was the VORTEX in an orbit which
could have been reached by the shuttle, or is the Covert report wrong?

I'm leaning towards the later.  From what I can see the report looked at
every type of launch vehicle/satellite failure including ones which clearly
could not be salvaged (e.g. launch vehicle explosion, satellite failure in
GEO) and it correctly indicates that those were not feasible shuttle
salvage missions.  Of the potential 'yes' cases, the key criteria appeared
to be orbital inclination (e.g. is it within the shuttle's limitations).

The key observational evidence we have is lack of sighting reports for the
payload.  If it was stranded in any orbit which could have been reached by
the shuttle - it should have been seen, even with its relatively low
inclination.  If the satellite was standed in a GTO then it would have been
much more difficult to observe.

Philip Chien, Earth News - space writer and consultant  PCHIEN@IDS.NET
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