Space Station momentum control and reboost requirements for two power generation concepts

Results are presented of dynamic structural analyses of 75 and 300 kW versions of a solar dynamic (SD) power supply for the Space Station (MSS). The SD is being seriously considered as an alternative to solar panels due to lower areal and mass requirements and higher efficiencies. The functioning principle is to use parabolic concentrators to focus sunlight on a heat engine to boil liquids to drive a turbine. Potential problems are foreseen in terms of the torques which would be experienced by the MSS and the subsequent orbital stability effects. The stability would be altered by changing aerodynmaic drag, altered moment of inertia and angular momentum and the altered center of mass location. The problem is exacerbated by the need to first equip the MSS with solar panels while the SD technology is developed. The analysis shows that the attitude control system will need to be redesigned and resized to accommodate MSS growth with either power system. The effects of the rotating parts of the SD system can be minimized, but further studies are required to determine the effects on the pointing accuracy of the SD, which must be 10 times as precise as that needed by a photovoltaic array.