NASA, the US Naval Research Laboratory and Georgia Tech researchers are working on a joint project to make the next generation of space circuits immune to radiation. These chips will be made from silicon germanium and will not require shielding like current-generation spacecraft chips. Silicon germanium is naturally resistant to ionizing radiation, and the researchers are now designing circuitry that can withstand cosmic rays.
"The holy grail in this field is getting sufficient radiation hardness without resorting to any of the high-overhead schemes, such as shielding, process hardening or triple modular redundancy," said principal investigator John Cressler, an EE professor at the Georgia Institute of Technology. "We are closing in on that goal, using silicon germanium electronics."
Most of the advanced electronics now used in space were designed for the relatively benign atmosphere of Earth. When used in spacecraft, conventional electronics often require heavy shielding to prevent radiation damage, as well as triple redundancy to compensate for exposure to cosmic rays.
SiGe is naturally resistant to ionizing radiation, which comprises smaller particles, such as electrons and protons, that move at high speeds but do not deeply penetrate circuits. Cosmic rays, however, involve heavy ions moving at speeds so fast that no medium can stop them. When cosmic rays rip through a circuit, they affect charge distribution, causing a local error in the circuit. So Cressler's group is designing its SiGe circuitry to withstand such errors.