Five Canadarm robotic arms were built. Five space shuttle orbiters were flown to space.

Did each orbiter have its own dedicated Canadarm? Or were they rather moved around from orbiter to orbiter, based on whatever equipment was ready at the moment?


1 Answer 1


No, they were not dedicated (except for 302 to Challenger, but that was a fluke, it was not the original arm on that Orbiter).

They swapped 'em around but not at random - if it made sense to leave them on an orbiter, they did.

I won't go through the whole history, but look at some early flights:

  1. Arm 201 flew on missions 2, 3, 4 (Columbia), then 7, 8, 41-B (Challenger)....
  2. Arm 302 flew on missions 41-C, 41-G, 51-F, 61-A, then was lost on 51-L (Challenger) (so it only flew on Challenger)
  3. Arm 301 flew on 41-D, 51-A, 51-C, 51-D, 51-G, 51-I, 31, 41, 39, 48 (Discovery), 52 (Columbia), 56 (Discovery)....
  4. Arm 303 flew on 61-B (Atlantis), 49 (Endeavour)....
  5. Arm 202 flew on 66 (Atlantis) and 80 (Columbia)....

Space Shuttle Missions Summary

Orbiter scheduling was complicated and they wouldn't leave an arm sitting in Palmdale while the Orbiter was down for extensive maintenance. Some of the complications of scheduling are discussed in the answer to this question: Why was Space Shuttle Atlantis selected for Mir docking so frequently? (You can see RMS annotations in the charts in that answer as well - in the second chart you can see Discovery fly with 301, 201, 201, 303, 301 - excerpt below, purple arrows).

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    $\begingroup$ Were the arms different? (Would they use a specific arm when a specific task was needed, or did any arm do?) $\endgroup$ Aug 31, 2020 at 20:22
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    $\begingroup$ @Speedphoenix at any one time they were intended to be identical, the differences were just due to manufacturing tolerances. The design changed over time though, becoming more computerized than the original. $\endgroup$ Aug 31, 2020 at 20:47
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    $\begingroup$ @Speedphoenix see space.stackexchange.com/a/36398/6944 for some details on managing the different arms. $\endgroup$ Aug 31, 2020 at 20:51

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