How fast do astronauts move while spacewalking?Jared Olson:

Their speed is limited mainly by how often they have to do "tether swaps." To prevent floating away, astronauts must have a tether attached to a handrail at all times in addition to their safety tether line, which moves along with them and extends to a max length.

So you attach to the next handrail, detach from the previous, move to the end and repeat. As Calvin Sissel mentioned, their path is planned out and rehearsed and they are trained to move slowly and deliberately. His 0.5 m/s is a good top estimate. If there was an emergency, they could detach their other tethers and simply pull themselves along their safety tether back to the airlock as fast as they could go hand over hand.

When they enter the foot restraint on the station robotic arm and are moved around by it, the arm programming is set to limit its max movement rate to less than eight inches per second.

While, theoretically, things could be done faster, everything is doneĀ very slowly to minimize risk.

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