I was reading the Mission Safety Evaluation Report for STS-32 and I noticed the following passage:

The STS-32 rendezvous was one of the most complex the Space Shuttle had ever attempted, requiring 11 major firings of Columbia's maneuvering engines.

That seems pretty high to me. Now my space flight experience only extends to Kerbal, but through those simulations I found that you can generally get into any rendezvous orbit in just 4-5 burns. Why did it take 11 this time?

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    $\begingroup$ While I don't have an authoritative answer, in this case, the rendezvous target was a payload designed to test exposure to space. I would imagine the rendezvous profile was especially designed to minimize the risk of contamination from thruster plumes, far more so than other cases. $\endgroup$
    – Tristan
    Feb 15 '17 at 15:53

First of all, remember that report is really old. A quick review of the wonderfully informative History of Space Shuttle Rendezvous shows that 9 or 10 burns* are not unusual for a rendezvous (see, for example, the writeups on STS-49 and STS-130).

* depending on whether you include OMS-2 in the count or not

STS-49 shuttle relative motion profile (May 1992)

There were some off-nominal events with the STS-32 rendezvous, however. As detailed in Lessons Learned from 7 Space Shuttle Missions, problems with the onboard radar resulted in flying a trajectory different from that planned, and additional braking towards the end. This may account for the additional burn(s).

Relative motion plot illustrating the planned and actual trajectories

  • $\begingroup$ I haven't tracked down the mission report yet, but as the mission included both a satellite deployment and a rendezvous, it seems likely that there would be a plane change in between, accounting for another burn or two. In addition, the mission continued for a few days after the collection of the LDEF, and they may have wanted to establish a different orbit after the pickup. $\endgroup$ Feb 15 '17 at 20:41
  • $\begingroup$ I agree with all you say, however, the context of remark in the Mission Safety Evaluation Report implies that the 11 burns were solely related to the LDEF rendezvous. "STS-32 rendezvous was one of the most complex the Space Shuttle had ever attempted, requiring 11 major firings of Columbia's maneuvering engines. All burns were completed, and LDEF was grappled by the RMS at 10:16 a.m. EST on January 12 at a distance of approximately 35 feet from Columbia." $\endgroup$ Feb 15 '17 at 20:44
  • $\begingroup$ Ah, yeah, my misread again. $\endgroup$ Feb 15 '17 at 21:37
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    $\begingroup$ STS-49 was a much hotter mess than was STS-32. Multiple rendezvous failures on flight day 4, followed by multiple failures on flight day 6, and by flight day 7, when STS-49 finally did capture Intelsat VI, the pluming from all those failed attempts had pushed the Intelsat 90 degrees off from expected attitude. I need to incorporate this into my talk on software testing tomorrow. $\endgroup$ Feb 16 '17 at 4:01

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