A Non-Conservative Retrieval of a Tethered Passive Astronaut.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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A non-conservative angular momentum is not conserved procedure is developed to safely retrieve a tethered passive astronaut on an extravehicular assignment EVA. The safe retrieval of a tethered astronaut by conservative procedures has been shown to be impossible unless the conditions upon initiation of retrieval are exceptional. Safe recovery is defined as a max rotation rate of 0.5 radsec, a max impact velocity of 5.0 ftsec, and a max centripetal acceleration of 8.0 ftsec squared. This last requirement is treated by limiting the tether tension to 100.0 lfb as the astronauts mass is taken as 13.04 slugs. To ensure the max impact velocity is not exceeded, the astronaut is reeled in at a constant rate of 5.0 ftsec. A safe recovery is achieved by insisting that the space vehicle track the astronaut during the EVA. Then, when retrieval is initiated, a force is applied through the center of mass of the space vehicle to null the angular acceleration of the astronaut with respect to the space vehicle.