thomsona@netcom.com (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 missions). 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 shuttle. 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 __ __^__ __________ | \ +---/ \---+ (========= |____\___________ +---\_____/---+ // >____)| | \__ \ \______//___ >/ |________| \ [ _____\ >|____________________\ \_______/ Roger, go at throttle up CHR$(32) the final frontier