Space power generation with a tether heat engine

A new concept of space power generation is presented that exploits thermal cycles of dilatation and contraction of a spinning tethered system exposed to solar radiation. The concept exploits a lightweight film made of shape memory material directly interacting with sunlight. A temperature variation cycle in the film is created by inducing periodic variation of the tether sun aspect angle. As the film length diminishes due to the increased temperature, the mechanical energy of the system increases and can be used to charge an energy storage device. A preliminary assessment of the system efficiency and power density is conducted. It is seen that in spite of the relatively low efficiency—for present shape memory alloys—of the phase transformation the system can benefit from a very high ratio between collecting surface and overall mass, which could make it an interesting alternative to photovoltaic systems for space power plans in the future. Current limitations appear to be in the design of an efficient power conversion and incident light modulation system.