From her home office in Brunswick, Maine, R. Aileen Yingst ’91 spends much of her time gazing out at the dusty crimson landscapes of Mars. As a senior scientist at the Planetary Science Institute, she roams the red planet with the Curiosity rover, helming a camera attached to its arm and scouring the planet’s geology for hints of life. We caught up with the geologist to learn more about rocks, space travel, and (of course), extraterrestrials.
Alumni News: Let’s start with the million-dollar question. Will we find evidence of life on Mars?
Yingst: It depends how hard we look. I suspect we’re not going to find evidence of a fossil sitting on the surface. I don’t think it’s going to be that simple. If it’s something we really want to look for, we’re going to have to invest a lot more time, effort, and careful systematic searching to find it.
I think your underlying question is: Do I think there was ever life on Mars? And I legitimately don’t know! Curiosity has shown that there were areas on Mars that were habitable, should there have been life. We have evidence of rivers, and, more importantly, of lakes—which means there was standing water at one time. Life likes that; it’s an environment where you can get energy from the sun but you’re not getting whopped around by the waves too much.
Alumni News: Ok, but how do we know it was water on Mars and not another substance?
Yingst: There are multiple lines of evidence—it’s a classic demonstration of how science is supposed to work. We found evidence early on from the Mariner spacecraft, which imaged what looked to be dry river beds, with streamlined islands and lakes. (With a streamlined island, a flowing river forms a teardrop shape because sediment is being deposited downstream from it.)
With various spacecrafts we’ve sent since then, we’ve built up more evidence. The Opportunity Rover discovered minerals, like hematite, that can only form with water in their matrix—plus sulfates and other types of salts that get concentrated when water evaporates. Then, Curiosity put the nail in the coffin by finding a mudstone. Mudstone grains settle in quiescent water; that’s why they form in lakes.
Alumni News: Speaking of water, we heard there’s an Occom Pond on Mars?
Yingst: Before Curiosity landed, we did geologic mapping to give us as much context as we could for when we were actually on the surface. We took the landing ellipse and some areas around it, divided that up into one-kilometer squares, and each of us mapped them. We named them after small towns—of course, one of the names I put on the list was Hanover. And so, everything in that quadrangle is named after places or geologic features in New Hampshire—including Occom Pond, Storrs Pond, and Moosilauke Basin.
Alumni News: So, when do you think we’ll get to visit the Hanover on Mars?
Yingst: That would depend on whether we want to invest in it. Do I think we could go right now? Sure! If we put the money towards it. It’s just expensive to leave the planet. But do I think that we could have people walking on Mars within 10 years.
Alumni News: Since we’re stuck on Earth for now, what’s the place we can travel on this planet that feels most like Mars?
Yingst: Mars is familiar and unfamiliar at the same time. It’s a terrestrial body, meaning it’s made up of the types of rocks and minerals—and geologic formations, like mountains and canyons and dry river beds—that geologists are familiar with on Earth. But there are profound differences: the red sky; seeing dust on everything and ne’er a tree anywhere; the fact that the landscape drops away from you more than you’d expect because Mars is a bit smaller than Earth. And even though it looks like a desert, which it is, it’s very, very cold [-80 degrees Fahrenheit on average]. It’s unique in some really profound ways.
In terms of visual similarity, it’s tough because Mars is not homogeneous. You might go with Arizona or the desert areas of Utah. But Mars is really cold, so that wouldn’t be quite right. You could go to Antarctica—that’s a nice dry desert—but it’s not quite right either because you still have vegetation, and areas where there’s ice and snow. You could go to Mauna Loa in Hawaii, which is a big shield volcano that’s kind of a dead ringer for Olympus Mons on Mars. If you went to places in Valles Marineris, a canyon on Mars, they might look like the Grand Canyon—but again, it’s similar yet different.
Mars is unique in some really profound ways, but the similarities remind you that we are creatures of the solar system and of the universe, not just of this one planet!