What would an extra-vehicular activity (EVA) be like on a spacecraft which consists of modules along a (100s of meters long) rotating tether that causes simulated gravity? See for example these slides and pdf for Joe Carroll's ideas about this kind of spacecraft/spacestation.

  • Could the astronaut stand and walk on the "roof" of a module?
  • Where does the astronaut go if he/she falls off the side of a module?
  • What would be easier and more difficult respectively, with rotation than in microgravity?

I'd guess that manual handling of tools would be much more Earth like and thus construction work much more efficient. Maybe large construction projects in LEO and beyond should be performed in rotating artificial gravity?


2 Answers 2


Assuming the EVA is at the module end, rather than the center of rotation, several interesting effects happen.

  1. things "fall".
    1. Things fall in an apparent arc, rather than down.
    2. This arc does appear to have a significant bend.
    3. This arc always is to trailing/back/antispin.
  2. Any item has weight varying by distance from center of rotation. This means that the items gain weight when lowered; the mass never changes, but the forces required to move/hold it vary.
  3. Any surface where the spin is to one's advantage is an area where one is likely to be working in a "downward" motion - specifically, down as "away from center of rotation."
  • $\begingroup$ From the standpoint of the guy on the pod, anything dropped falls trailing of where he dropped it. Also, @RoryAlsop, it does NOT fall due away - it falls in a straight line at a right angle to the center - because all its velocity is in fact tangential, and none is actually radial; it's only a centripital force (in this case, the pod itself moving in an arc) that keeps it from moving in the direction of rotation at moment of release. $\endgroup$
    – aramis
    Commented Jun 6, 2014 at 16:59
  • $\begingroup$ I wasn't disagreeing with the apparent arc at all. I am always amused watching my kids fail to catch a ball they throw to each other while spinning on a roundabout. You are correct on the other point though :-) $\endgroup$
    – Rory Alsop
    Commented Jun 6, 2014 at 17:50

Things that get easier:

  • Applying force (linear or rotational). Gravity allows you to have sufficient friction to counteract forces.
  • Storing objects. If you store tools or parts in a basket, they stay there. No more need to tether everything all the time.

Things that get harder:

  • Moving heavy objects.
  • Working in a space suit: EVA suits are heavy.
  • Getting rescued if you fall off the spacecraft.

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