Typically the reason is often the need for radiation hardening. Operating in space, or on the surface of Mars, outside the radiation shield that is the earth's

Typically the reason is often the need for radiation hardening. Operating in space, or on the surface of Mars, outside the radiation shield that is the earth's magnetic field, is a very different, and very harsh, environment for electronics. http://en.wikipedia.org/wiki/Radiation_hardening http://en.wikipedia.org/wiki/Radiation_hardening Pertinent quote from the above Wikipedia article: > Due to the extensive development and testing required to produce a radiation-tolerant design of a microelectronic chip, radiation-hardened chips tend to lag behind the cutting-edge of developments.