posted 09-01-2008 09:31 PM            

The evolution of the shuttle crew size is interesting. The four OFT flights managed some ambitious missions lasting up to a week with only two crew members. STS-5, 6, 7 and 8 were planned with four crew members: commander (CDR), pilot (PLT) and two mission specialists (MSs). (Early in shuttle planning — in the late 1970s, before I arrived at Johnson Space Center — the plan was to have only one MS on routine missions, if I recall correctly.)

In December 1982, one additional MS was added to each of STS-7 and 8, at the direction of the associate administrator of manned space flight, Gen. James Abrahamson, to "solve" the space motion sickness problem, once and for all, under the direction of Dr. Bill Thornton. Interestingly, the first flight, STS-7, went to Thagard (Thornton's "protege") and Thornton himself went on STS-8. This brought the baseline crew size to five. It also didn't solve the motion sickness problem...

About that same time, the STS-9/Spacelab-1 crew was in training, and MS Bob Parker was also being trained as the flight engineer (FE), assisting the CDR and PLT during launch and re-entry. I recall hearing that he was being spread too thin, between FE training and payload training, and there was discussion about adding a dedicated FE to offload Parker. In the end, that didn't happen, but all subsequent Spacelab missions did have dedicated FEs designated MS2. So STS-9/SL-1 was the only Spacelab with six crewmembers; all subsequent ones had seven.

The STS 61-A/Spacelab D-1 (first dedicated German Spacelab mission) carried eight crew members, but after Challenger and the addition of the bailout system and spacesuits, the maximum number flown was always seven.

Before Challenger was lost, except for 61-F and 61-G, the eventual routine seems to have been five career astronauts (CDR, PLT and three MSs) and up to two payload specialists (PSs). After Challenger, the crews were kept to five, with two PSs only on Spacelab missions (the American PS position on STS-47/Spacelab-J was assigned to a MS, but the Japanese flew their own PS). As I recall, STS-39, an unclassified DoD mission, required five MSs to execute all the payload operations, and that seems to have become the standard thereafter.

posted 09-02-2008 11:10 AM               

quote:

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Originally posted by John Charles:
(Early in STS planning — in the late 1970s, before I arrived at Johnson Space Center — the plan was to have only one MS on routine missions, if I recall correctly.)

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posted 11-27-2019 02:10 AM               

Consider that for a spacewalk, two crewmen were needed plus a third to monitor the spacewalkers and use the manipulator arm. Was the idea of seven crewmen to ensure that there was at least one or two seats for ESA astronauts? And if so, was the ESA always paying for those seats each flight?

posted 11-27-2019 09:53 AM               

The understanding I took away was crew size depends on payload requirements (manpower and weight), the mission timeline and crew time required for operational needs on the flight. There was no rule that "the minimum is five astronauts." Five was a minimum required to do a rendezvous, some robotics and EVA with a manageable timeline.

This evolved with technology. The ability to do remote work (working payloads, robotics, P/TV) from the ground in Mission Control and Payload Operations was a game changer. It enabled the planning of the rescue missions and STS-135 flying with a crew of four.

posted 11-27-2019 10:33 AM               

quote:

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Originally posted by Explorer1:
Was the idea of seven crewmen to ensure that there was at least one or two seats for ESA astronauts?

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