麻豆约拍

Femi talks to two satellite designers, Trevor and Simon, about the expansion of metals in space. The SOHO satellite, which is always in view of the Sun, has a hot side at 80掳C and a cold side at -10掳C. Ordinarily, this temperature difference would cause the satellite to warp.

Femi investigates a low-expansion metal called Invar which has a very low coefficient of expansion. However, it is much heavier than the aluminium used in the satellite. In practice, the satellite is artificially heated and cooled to even out its temperature.