|
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 will 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.
|
|
Increased Satellite Functionality at Lower Launch Cost
|
|
Silicon carbide high temperature electronics will reduce spacecraft launch weights and increase satellite functional capacities.
|
|
|
Present-day commercial satellites 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. This would enable substantial weight savings on a satellite, or at least allow greater
functionality (i.e., more transponders in a communications satellite) by utilizing the space and weight formerly occupied by the termal management
system. Furthermore, SiC electronic devices have also been shown to be less susceptible to radiation damage than corresopondingly rated silicon devices.
Therefore, SiC electronics could also reduce the size and weight of shielding normally used to protect spacecraft electronic components from space
radiation. Given the exorbitant per pound costs of launching payloads into earth orbit, the weight savings gained by using SiC electronics could have
large economic and competitive implications in the satellite industry.
|
|
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 and aerosurfaces 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 serious drawbacks, as the wire runs add a substantial amount of
weight, fuel cooling has harmed aircraft fuel efficiency, and both have negatively impacted aircraft reliabiltiy.
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. Uncooled operation of 300 - 600 C SiC electronics and sensors mounted would save weight
and increase reliability by replacing hydraulic controls with "smart" electromechanical controls. SiC-based distributed control electronics would
eliminate wiring and connectors needed in conventional sheltered-electronic control systems.
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.
Additional Background Information
Second International High Temperature Electronics Conference, Session I, Charlotte, NC, June 5-10, 1994.
Proceedings of the 9th Symposium on Space Nuclear Power Systems, January 12-16, 1992.
|
|
