Of course, Safer is useful only if the astronaut is conscious. What if an astronaut gets bonked on the head, becomes untethered, and can't operate the jetpack? "A rescue effort could and would be undertaken by the second spacewalker and/or other members of the spacestation crew," says Michael Curie, a spokesman for NASA's space operations. He wouldn't speculate on the exact steps a rescue team would take, because they would depend on the circumstances. But he adds, "we are really happy with the tether-and-Safer approach."