Why Haven't we Returned to Venus' Hellish Surface?

It was 40 years ago this month that Venera 9 transmitted the first surface images from Venus, a hellish world that is not only hot, but also under high pressure at the surface.

The Soviet Union sent several spacecraft to the surface in the 1970s and 1980s. The longest any of them survived was just two hours. Could we do better now? NASA’s Geoffrey Landis has hope that new technologies could get more surface science out of Venus, eventually.

Landis is a researcher in advanced concepts and a Venus advocate at the NASA Glenn Research Center who has several streams of Venus research ranging from astrobiology to atmospheric flights. He’s also been tinkering with several concepts over the years, such as a “Zephyr” wheeled rover that would sail across the parched surface using Venus winds. Most recently, he and colleagues at NASA Glenn began work on the Glenn Extreme Environment Rig (GEER) that would be big enough to test spacecraft in a Venus-like environment.

“Venus has been tremendously difficult to land on,” Landis acknowledged in an interview with Discovery News, adding that the surface is hotter than a conventional oven. One key challenge facing robotic explorers is conventional silicon electronics would not work. Silicon degrades in the acidic, hot environment because there are so many electrons from the atmosphere flowing across the “band gap” across which electric current flows.

He suggests a couple of ways around it. One idea: silicon carbide is a semiconductor that has a high-energy band gap and performs well at high temperatures. Or, one could refrigerate the electronics and leave the rest of the spacecraft exposed to the elements — as long as the spacecraft was made of a tough, light material like a titanium pressure shell.

Or perhaps future robotic explorers could avoid the surface altogether. Another group at the NASA Langley Research Center has speculated that airships — even airships with humans — could easily work in the more temperate latitudes about 35 miles (50 kilometers) above the surface. The atmosphere is at a more Earth-like pressure there. As for composition, it is mostly carbon dioxide — meaning that an oxygen balloon would float because it is lighter than the surrounding atmosphere.

While Landis says there is real value to going all the way down to the surface — “we’ve learned so much on Mars by sending rovers to the surface” — Venus is full of mysteries no matter what altitude one studies. The upper atmosphere is full of ultraviolet-absorbing particles, but nobody knows exactly what those particles are. Some scientists speculate they could even be microbes, a form of life on Venus.

Even the lower atmosphere of Venus is dynamic, with winds flowing at hundreds of miles an hour. Getting a better picture of how the entire atmosphere works would tell us more about the greenhouse effect generally, Landis says.

Read more at Discovery News