And, if a robot arm were to swing out towards you, for safety reasons you would want to be able to immediately stop it and push it back without harming yourself, reverse that motion instantly. For one thing, that requires a back-driveable actuator.
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It was not supposed to be used until they got to the Moon. It had no heat shield, so could not be used to re-enter the Earth's atmosphere. But it could keep them alive until they got there.
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