Today astronauts perform maintenance and experiments outside of the orbital shuttle frequently... and one has to question, "What is NASA's rescue plan if an astronaut floats away?" Because astronauts are usually safely tethered to the exterior of the spacecraft or ISS, NASA feels confident that this scenario is unlikely... and if the braided steel tethers do fail, the endangered astronaut has a backup plan with jetpacks...! Each astronaut has a built in emergency nitrogen-jet pack called the SAFER 'Simplified Aid For Extra-vehicular activity Rescue' to help propel them back to safety.
In a worst-case situation, the only rescue option, according to Oberg, would be for a second astronaut to link together several tethers end-to-end, attach them to the station, and then use his SAFER pack to jet over to his crewmate and haul him in. Certain conditions could make a rescue easier, he says. If an astronaut floated away more or less at a right angle from the station's orbit, orbital dynamics (which require too much math to explain here) dictate that he would float back toward the station in about an hour.via gizmodo