NASA develops new hell-resistant electronics for a mission to Venus

By Jessica Hall

“I think that the sun is a flower, that blooms for just one hour.” –Margot, in “All Summer In A Day”

Ray Bradbury’s short story, “All Summer In A Day,” tells of a girl named Margot, and how terribly she misses the sun after her family moved from Earth to Venus. Under the all-enveloping, oppressive Venusian clouds and the constant beating rain, there is nothing for Margot that doesn’t seem to hurt.

It’s hard to think of Venus without thinking of that story, because it captures something essential about Earth’s “evil twin.” Venus is not exactly a comfortable vacation spot. Bradbury knew Venus would be an awful place to live, but he didn’t know how punishing conditions on Venus actually are. It eats spacecraft, almost literally. The place is so awful we gave up going there. Russia’s Venera 12 spacecraft failed after less than two hours on Venus, practically slagged by the hostile atmosphere, corrosive rain and searing heat. There hasn’t been a lander mission to Venus since 1984. But all that could be about to change, thanks to some folks at NASA who have just built a new chip capable of withstanding the hellish surface of Venus for weeks.

Margot would have buried her head in her hands and wept to hear that the Venusian rain isn’t water but sulfuric acid. But it’s worse even than that. It’s actually so hot on Venus that the rain never even hits the ground, evaporating back into fog and clouds because of the hellish heat. The mean surface temp on Venus is a balmy 863° F (461° C). That ambient temperature is enough to melt zinc. If we were settling Venus like we settled the American West in the Oregon Trail, to melt lead for bullets all you’d have to do is fill a smelting cup and hold it out the front of your covered wagon. And the atmospheric pressure at “sea level” on Venus is a mere 90x that of Earth. These combined factors mean that the electronics array on any Venus-bound spacecraft is DOA. Copper traces, and any exposed sensor or metal, are instantly corroded into uselessness.

But NASA wasn’t willing to settle for that. Their Glenn Research Center turned to materials science and found that silicon carbide is capable of doing what silicon transistors currently do, but under Hadean conditions just like those on the surface of Venus. “We demonstrated vastly longer electrical operation with chips directly exposed — no cooling and no protective chip packaging — to a high-fidelity physical and chemical reproduction of Venus’ surface atmosphere,” said Philip Neudeck, project lead. “And both integrated circuits still worked after the end of the test.”
SiC transistors have the power consumption and heat dissipation advantages of conventional CMOS integrated circuits. But compared with conventional ICs, silicon carbide laughs at the Venusian heat and chemical attack. Fun fact: NASA initially started their work on SiC transistors because they needed sensors that could stand up to the temperatures inside a rocket engine. This particular SiC wafer was built for sensors in the engines of ultra-fuel-efficient aircraft. Turns out it’s capable of handling a sortie to Venus, too.

Project scientists built the SiC chip in the custom fab they have at Glenn, and then assembled it into a simple device called a ring oscillator that’s useful for monitoring the effects of pressure and temperature. The wires were insulated with MgO ceramics and the junctions hand-sealed with glass. When they put their new chip inside the Extreme Environments Rig, project scientists got more than 500 hours out of their SiC chip before it finally succumbed. That’s three weeks to do science on the surface of Venus. Hundreds of times longer than the best previous contender. And this is just an alpha test. With some more applied science, who knows what kind of indestructible spacecraft we can build?