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Why would you ever search for life on a planet which is surrounded by clouds of lethal sulfuric acid above a surface hot enough to melt lead?
Venus hasn’t nearly gotten the headlines Mars has when it comes to the possibility of microbial life-forms inhabiting (or at least having once inhabited) it, but a team of researchers at MIT are out to challenge that. They believe that Venus is underrated when it comes to astrobiology. There are microbes on Earth that thrive in sulfuric acid, so hypothetically, it’s not impossible for life like to have developed on Venus — but no one ever looked for it.
MIT researcher Sara Seager thinks Venus deserves more attention. She and her team have figured out a concept for a series of privately funded missions that involve probes being sent to Venus to make out how habitable the clouds of Venus could be, scour them for signs of alien life, and maybe even discover actual microbes. Some chemical anomalies could suggest life, and the instruments on Seager’s first Venus Life Finder Mission probe are made to find it.
“This mission’s main science instrument is an autofluorescing nephelometer,” she said. “It will shine a laser through a window in the probe to hit cloud particles, look for fluorescence, and measure the backscattered light. Nothing scatters equally, so the way a particle scatters light as a function of angle gives clues to its composition.”
If something is creeping around in those clouds, it could be similar to the Earth microbe Ferroplasma acidiphilum. This single-celled extremophile does’t even have a cell wall to protect itself and can still survive in sulfuric acid. What sets it apart from just about every other organism on the planet is that it can use the iron it metabolizes to organize most of its proteins. This might be a primordial ability that existed when life first spawned on Earth. It is possible life awakened on substances made of iron and sulfur, such as pyrite, and ate iron for its innards.
Venus might have once been Earthlike. While that is still being debated, F. acidiphilum is one organism that could give us a glimpse into what life could be like if it actually exists in Venusian clouds. Every living thing on Earth metabolizes sulfur to some extent. Some organisms are capable of processing much more than others, such as bacteria like Bacillus subtilis and certain types of E. coli, and there are also bacteria that can oxidize sulfur and produce sulfuric acid. Whether that might explain the high levels of sulfuric acid in Venus’ atmosphere is unknown.
“We are mostly looking for evidence that the Venus cloud particles are not pure concentrated sulfuric acid — extremely harsh for life — but contain organic molecules. We won’t be able to identify which molecules are present, just that there is rich, unexpected chemistry, of the kind that life both needs and makes.”
Just like on Mars and some really alien places on Earth, organics don’t always mean life. The presence of these carbon-based substances excites astrobiologists so much because they are part of the chemistry that life, at least as we know it, needs to get going. We are carbon-based life forms. There could be others out there if extraterrestrial life is anything like the life we know of. However, we also have to watch out for life as we don’t know it and possibly need imagined it. Hypothetical microbes in the atmosphere of Venus may use sulfur in some bizarre way.
The Venus Life Finder probe will be loaded onto Rocket Lab’s Electron rocket, which will take five months to zoom 38 million miles to Venus so the probe can fly through the swirls of toxic clouds for three glorious minutes. What it could find out in that time may give more momentum to future Venus missions. Seager isn’t expecting to find any obvious signs of life on the first mission. Maybe if larger space agencies start paying more attention to this poisonous planet, an actual sample return mission could happen, and we could seek out microbes in a lab on Earth.
“Space agencies are already supporting small missions in the form of CubeSats,” Seager said. “Hopefully ,everyone can continue to grow together to see the power in small focused space science missions.”