Radiation tolerant, extreme temperature capable electronics are needed for a variety of planned NASA missions. For example, in-situ exploration of Venus and long duration Europa-Jupiter missions will expose electronics to temperatures up to 500 Deg.C and radiation of 3 Mrad (Si) total dose. During this program, United Silicon Carbide will extend the capability of its SiC JFET integrated circuit fabrication technology to produce electronics compatible with such extreme environments. Silicon Carbide (SiC) junction field effect transistor (JFET) based electronics are ideal for these environments due to their excellent radiation tolerance and high performance and reliability over an extremely wide operating temperature range. SiC electronics can be used in applications ranging from low power, low noise mixed signal electronics for precision actuator control, sensor interfaces, and guidance and navigation electronics to power electronics for power management and distribution and power processing units. Systems built with SiC based electronics will have longer storage and operating lifetimes when compared to systems built with existing silicon electronics. Use of SiC integrated circuits will also lower system mass, volume, and power by reducing or eliminating the need for cooling and radiation shielding. In Phase I, we will perform measurements and modeling to show the feasibility of extending the capability of our SiC integrated circuit (IC) technology to meet NASA's extreme environment needs. In Phase II, we will fully develop the extreme environment capable SiC IC technology and demonstrate it through test and delivery of a high temperature, radiation hard, mixed signal sensor and control circuit. Following Phase II, we will provide access to the process technology and related design intellectual property through a commercial fabrication service so that NASA and others can fully leverage its capability.