Space Studies Institute Report on Space Shuttle External Tank Applications by J. Alex Gimarc 12-01-1985 copyright Space Studies Institute There are several items of interest with a rotating station. The first is that there are indications that the body cannot tolerate rotation rates much greater than 1-3 rpm (89). Thus the station should be kept large enough to keep the rotation rates small. The second concern is to minimize coriolis forces (13). This is also accomplished by keeping the station large. The third concern is operational. There are docking problems associated with arriving at and leaving a rotating station. The typical proposal is to make the center of rotation the docking port. This is feasable and should work. The last concern is with the very real problem associated with adaptation to zero *G* by visiting crews. If a station is designed for habitation which includes living quarters with artificial gravity, there may be problems when the crew transitions to zero ’G' for the ’workday’. This may or may not be a problem. However, the unhealthy effects of long-term weightlessness on the human body are serious enough that this solution should seriously be studied. B. Momentum Exchange Momentum storage and exchange are related in this context to the raising and lowering of orbits. Due to the forces discussed above, if a tethered mass is released from a stationary orbiting station, it and what it was released from will assume stable orbits with the closest approach seven times the length of the tether. If the release was from rotating tether, the closest approach of the final orbits would be as much as 14 times the length of the tether (13, 56). The equation for mass and orbital radius is also on the diagram. The orbit of any facility or structure can be raised or lowered by momentum exchange procedures alone. If the operation is conducted with enough planning, the station may not require thrusters to keep it in orbit. For example, if an orbiter arrives at a space station, it uses a certain amount of OMS fuel to get there. If the orbiter meets a tether tens of miles below that same station and is winched up into the station that same OMS fuel becomes excess and can be transfered to the station for OTV refueling (16, 37). When the orbiter leaves, it can be winched down to the capture altitude or even lower and released. If is is released far enough away from the station, no OMS burn will be necessary for reentry. The net gain in this operation is the OMS fuel excess delivered to the station. The net loss is the time that the station spends in the lower net orbit due to the winching up of the orbiter.
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