National Aeronautics and Space Administration

Glenn Research Center

Spacecraft

Artist Conception of Exploration Spacecraft Orbiting Planet Mercury

Increased Satellite Functionality at Lower Launch Cost

Compact and lightweight silicon carbide high efficiency power electronics will reduce spacecraft launch weights and increase satellite functional capacities.

It is now well-demonstrated that silicon carbide power devices can enable substantial improvements to the size, weight, and efficiency of power management and distribution circuits and systems. The faster switching speed of high-voltage silicon carbide power devices compared to similarly rated silicon power devices enables the practical use of much higher internal switching frequencies in power conversion circuits. The higher internal switching frequency in turn enables power conversion circuits to employ much smaller transformers and capacitors that are almost always the vast majority of the size and weight of a power converter circuit. While the amount of benefit is always application-specific, some silicon carbide converter demonstrations have cut the volume and weight by more than 5-fold compared to correspondingly rated converters implemented with standard silicon power devices.

Spacecraft often require thermal radiators to dissipate heat generated by the spacecraft’s functional electronics. These electronics, currently based on silicon or gallium arsenide semiconductors, would fail if they were not properly cooled by the spacecraft’s thermal radiators. Because silicon carbide electronics can operate at much higher temperatures than silicon or gallium arsenide, the size and weight of such radiators on a spacecraft could be greatly reduced or even elimated.

The above silicon carbide electronics system benefits will enable substantial weight savings on a satellite, or at least allow greater functionality (i.e., more scientific instruments or communications transponders) by utilizing the space and weight formerly occupied by the larger silicon-based power and thermal management subsystems. Given the exorbitant per pound costs of launching payloads into earth orbit, the weight savings gained by using silicon carbide electronics could have large economic and competitive implications in the satellite industry.

Solar System Exploration

Spacecraft with high temperature, radiation hard silicon carbide electronics will enable challenging missions in both the inner and outer solar system.

Radiation hard high temperature silicon carbide electronics will play a key role in future missions to the hostile environments near the sun and on the surfaces of the inner planets. Long-term operation of probes within Venus’s scorching 450 C atmosphere will require the use of uncooled silicon carbide electronics. For spacecraft operating near the Sun, silicon carbide electronics would enable significant reductions in spacecraft shielding and heat dissipation hardware, so that more scientific instruments could be included on each vehicle.

Space nuclear power is expected to play a key role in the advanced exploration of the outer solar system. Future space nuclear power systems will require control and monitoring circuits for safe and optimum reactor performance. Use of heat-tolerant radiation hardened SiC circuits will greatly reduce the shielding needed to protect the reactor control electronics, and enable placement of the electronics in close proximity with the reactor, both of which will trim considerable weight from the power system.

Advanced Launch Vehicle Sensor & Control Electronics

Silicon carbide electronics and sensors that could function mounted in hot engine and aerosurface areas of advanced launch vehicles would enable weight savings, increased engine performance, and increased reliability.

Complex electronics and sensors are expected to enhance the capabilities and efficiency of advanced space launch vehicles. Many of these electronics and sensors monitor and control vital engine components that operate at high temperatures. Since today’s silicon-based electronics technology cannot function at high temperatures, these electronics must presently reside in environmentally controlled areas. This necessitates the use of long wire runs between the sheltered electronics and the hot-area sensors and controls or the fuel-cooling of the electronics and sensors located in high-temperature areas. Both of these low-temperature-electronics approaches suffer from significant drawbacks of added weight and increased system complexity.

A family of high temperature silicon carbide electronics and sensors that could function in hot areas of the launch vehicle would alleviate the above-mentioned technical obstacles to enable performance gains. Silicon carbide based distributed control electronics and sensors that could operate in very harsh environments would eliminate wiring and connectors needed in conventional sheltered-electronic control systems. Furthermore, uncooled operation silicon carbide high-power electronics could save launch vehicle weight by replacing hydraulic actuator systems and fluids with fluid-free electromechanical controls.

SiC-based sensors are being developed for launch vehicle applications by the NASA Glenn Gas Sensors team, as well as the NASA Glenn Physical Sensors team.