A new study indicates that there could be life on Venus. Not the Venusian life you might have read about in old pulp fiction novels, but life nonetheless — tiny microbes possibly living and reproducing high above the planet's atmosphere. Sara Seager is a professor of physics and planetary science at MIT, and one of the study's authors. She spoke with GBH All Things Considered host Arun Rath. This transcript has been edited for clarity.
Arun Rath: So we understand that the big clue here that there could be life on Venus is the presence in the atmosphere of a chemical called phosphine. Could you tell us what phosphine is and why that would point to the possibility of life?
Professor Sara Seager: Phosphine is a gas made of a phosphorus atom and three hydrogen atoms. And actually, phosphine is toxic to life that needs oxygen, such as us humans. It was used as a chemical warfare agent in World War I. Now, on Earth, phosphine is only associated with life, either produced by us humans as reagents in a lab or as a pesticide, or by bacteria living in oxygen-free environments.
Rath: So if there is phosphine on Venus, unless we rewrite what we understand about chemistry, that seems like that would be associated with life.
Seager: Well, Venus is a pretty crazy world, so we're not claiming that we have found life or even signs of it on Venus just ahead, to back up a bit. We're saying that we're confident we have a robust detection of phosphine gas on Venus and we're leaving that to equate crazy interpretations out there for further work.
Rath: Well, let's talk about the evidence. I remember enough from high school that you can tell by looking at the light from a planet certain things about the chemical composition of its atmosphere. How are you figuring out that there is phosphine potentially on Venus?
Seager: Well, all molecules rotate, vibrate, interact with light, and they absorb light. Our team used radio telescopes actually to look at Venus, at very long wavelengths we know that phosphine gas absorbs. And specifically, we use two different telescopes. One is the James Clerk Maxwell telescope, atop Mauna Kea in Hawaii. The other is ALMA, the Atacama Large Millimeter Array, a series of about 46 telescopes working together.
Rath: Using radio telescopes in this way to analyze the atmosphere of a planet — is that a fairly common thing?
Seager: Well, it's not super common, but our solar system's planets are bright enough so that we have enough energy coming from them to use radio telescopes.
Rath: Understood. And is there a reason why it hasn't been detected earlier, given how long we've studied Venus?
Seager: You have to understand that the search for life on Venus is an incredibly fringe topic. It's almost laughable, actually. So if you wanted to propose to use a telescope to search for signs of life on Venus, chances are your proposal would be completely rejected. And the team's first proposal was rejected. But thankfully, a telescope allocation committee decided to take a risk.
Rath: And it's considered absurd to think about life on Venus because it's 800 degrees with clouds of sulfuric acid, all the things we learned about in school about the harshness of how things are on Venus.
Seager: Exactly. No life as we know it could survive anywhere on Venus.
Rath: So no one thought to look for phosphine before, thought it would be worthwhile.
Seager: Pretty much. In science and especially in astrobiology and the search for life, the line between what is considered completely crazy and what is considered mainstream is constantly shifting. So I think we've shifted the needle a little bit here. But phosphine itself — most people aren't aware of that gas and it's a pretty niche topic in biology.
Rath: Tell us about where things go from here in terms of research. Where do we pick up on this to find out what this is all about?
Seager: First of all, our team members are hoping and planning to try to confirm the presence of phosphine gas by using the same ALMA radio telescopes again, and also by using ground-based infrared observatories. I actually think we need to go to Venus, to send a space mission with a focused instrument, not only to confirm the presence of phosphine gas, but to search for other gases, other molecules that might be produced by life and maybe even to search for life itself.
Rath: The U.S. and other countries have sent a number of missions to Mars, and I think that the consideration of life is part of that. It seems like you think this could generate that interest and support for robotic missions to Venus?
Seager: I definitely think so.
