Because diamonds can withstand extremely high temperatures and corrosive conditions, and because they are transparent to most forms of light and electromagnetic radiation, they are ideal for use as windows in industry and in space probes, including the 1978 Pioneer space probe to the surface of Venus. Eight of the windows were sapphire and one was a diamond. (source)
|CLEAR VIEW of Venusian atmosphere was possible on Pioneer Venus probe because of this diamond window the size of two pennies stacked together.|
Mal Meredith, NASA Systems Division associate manager, inspects the window during probe assembly in El Segundo last February.