Hi, Consider a "T" shaped object in space. The top of the T points at the Sun, and the very long leg points away from the Sun, such that it is entirely in the shadow of the flat top. Heat is absorbed by the top of the T and used to heat a fluid. Heat is rejected along the sides of the leg of the T which has a much greater surface area than the top of the T, allowing heat to be rejected at a much lower temperature. The resulting temperature differential can be used to create a very efficient heat engine, because of the very low temperature attainable on the cold side, combined with a very high temperature of the high temperature side if it has a "selective surface".
Regards, Robin van Spaandonk <[EMAIL PROTECTED]>
