QUESTION
What is the material that the solar arrays on Hubble made of?

ANSWER from Mark Kochte on April 30, 1996:
The solar arrays are composed of hundreds of solar cells. The solar cells
themselves are made up of a couple of layers of silicon chips, with one layer
exposed to the sunlight, and the other on the back or dark side. On the exposed
silicon layer is a microfine network grid of metal for electrical contact,
large enough to collect the current from the silicon chips, yet small enough to
not obstruct the incoming light. As light/photon energy/'packets' hit the
exposed silicon chip, an electrical current is set up between the exposed and
>unexposed chips. The metallic grid then takes this building electrical charge
and funnels it off to a battery for storage.