Meenakshi Wadhwa is the first to say she is lucky to be alive.
On August 2, 2017, Wadhwa and colleagues were prospecting for volcanic rocks in the cooled lava fields of Iceland. After collecting some samples of basaltic rock, which they hoped to use as a proxy for Martian rocks, the team hopped in their vehicles to drive back to their lodgings. Wadhwa sat in the back seat of one of the SUVs, snapping pictures out the window.
Their caravan encountered another group of cars, and her driver decided to pass them. As her vehicle overtook the others, one of the other cars swerved, colliding with her SUV and flipping it. Wadhwa was thrown 30 feet from the vehicle. She suffered a broken pelvis, a punctured lung, broken ribs, a broken shoulder, and several other injuries. “I was a mess,” she said.
She was airlifted from Iceland to Massachusetts General Hospital and later moved to Memorial Hermann Hospital in Houston, where she underwent several months of rehab and physical therapy. Last December during her rehab, Wadhwa used a treadmill equipped with assistive devices that simulate lower gravity, easing the burden on her bones. She was enthusiastic about it, imagining herself running on Mars.
Wadhwa, 50, is a meteoritics researcher at Arizona State University who focuses on how meteorites can tell stories about the early solar system. She grew up in Chandigarh, in northern India, in the foothills of the Himalayas. She hoped to attend architecture school, but when she didn’t get in, she began wondering about the mountains — how they formed, and what stories they could tell. She studied geology in college and wound up doing her graduate work at Washington University in St. Louis. There, someone handed her a piece of Mars, and she’s been in its thrall ever since.
The fourth planet may be dry and barren now, but in its past it was much like Earth: a warm, watery world full of mountains like the ones where Wadhwa grew up, and with deserts like the one she lives in now. Wadhwa studies the rocky planets’ shared past, including how Earth and Mars formed and how they got their water. To do this, she uses Earth rocks and meteorites, including some from the asteroid belt and some from Mars and the moon.
Like Earth, Mars is continually pelted by asteroids — leftovers from the early solar system that did not grow up into planets. In the past, big collisions have sheared off chunks of Mars, which then soared into space and, rarely, landed here on Earth. Wadhwa’s research on trace elements inside these meteorites has helped geochemists understand the history of Mars, including its watery past. By comparing these meteorites with Earth rocks, scientists can begin to learn how terrestrial planets begin to form and grow.
Quanta talked to Wadhwa about the hazards of fieldwork, the eerie feeling of holding a chunk of another world, and her efforts to construct a holistic picture of the solar system’s history using the crumbs left over from its formation. The interview has been condensed and edited for clarity.
You grew up at the base of one of this planet’s most impressive geological features. How did you get interested in geology on other worlds?
I grew up in India, and I always loved science. I went to an all-girls school, and I never grew up with the type of peer pressure that you sometimes encounter here in the U.S. among young girls, where you’re afraid to speak in front of your colleagues or friends because you don’t want to look nerdy. We were all trying to do our best.
My freshman year in college was the first time I felt like I didn’t belong. It was an all-male faculty. Someone told me, “Geology is hard for a girl, because you have to do fieldwork, and usually women have a tough time with that.” I was sort of made to feel like I didn’t fit in.
After that, I applied to grad school. I was always kind of fascinated with other planets, and I thought, wouldn’t it be cool to be able to apply my geological insight to learning something about the solar system? I didn’t know how I would go about doing this, but I knew there weren’t many places in India where I could do it, so I started applying to schools in the United States.
Applying from India, at a time when there was no internet, I had the Barron’s guide to graduate schools in the U.S., which was outdated by like 10 years at that point. I didn’t care about geography or any of that. I didn’t care if it was East Coast or West Coast or the Midwest. It was all half a world away.
So I was accepted into Washington University. I wasn’t sure what I wanted to do, and I took a class with my adviser. I hadn’t seen many women faculty in this area at all, besides her. And then she asked me, “Hey, do you want to work on these Martian rocks?” And I was like, “What? Really? We have Martian rocks?” She said, “We are pretty confident they are from Mars.” I was totally intrigued. I thought, “Wow, this is really cool, I can actually do geology on Mars!”
What is it like to hold a piece of Mars or the moon? Why are these samples so special?
It’s kind of like a book chapter in the history of a planet. If you know how to read it, it can tell you a lot about what went on in a particular time and place. There’s a lot of information encoded in these rocks. We’ve got the tools to be able to read that code. To me, it’s a really cool way to be able to see a planet sometime in the past and learn something about how it came to be the way it is now. We use Earth rocks all the time for that purpose. These rocks are no different.
Speaking of bits of Mars, a meteorite from Mars fell to Earth in 2011 and landed in Morocco. You sliced one piece of this meteorite into three chunks and left them exposed to the elements in Arizona’s Sonoran Desert for three years. Did you feel weird about it? Like, “We’re going to throw this fresh meteorite outside and see what happens”?
That was a serendipitous experiment. I’m not going to take credit for the idea. Our collections manager at the Center for Meteorite Studies, Laurence Garvie, is super interested in what happens to things when they are sitting out in the desert. In a half-kidding way, he was like, “Here’s this fresh sample, let’s put it out there.” And I was like, “Huh. You know, that’s actually a great idea.” Because we don’t have anything from Mars that is that fresh. The previous [meteorite] fall happened like 50 years ago. So this was a great way to do a reality check — what’s going on with these samples?
We left it in a part of the desert that is not traversed so much. But every so often during monsoon season, there are these gully washers that go through there. We put it under a steel wire mesh, but that wouldn’t have kept it from being washed away in a really big rain. We did the best we could in terms of placing it in a place where it was a little out of the way. But we were lucky we were able to locate it again after two or three years.
What is fieldwork like for you? Can you tell me about your car accident? Did it change anything about how you approach your work?
This was one of these projects I had been waiting to do for a while, and I was super excited about it. I had done some fieldwork in Antarctica to collect meteorites, but this was going to be the first fieldwork where we would be collecting Icelandic volcanic rocks as analogues of Martian volcanic materials, with the goal of understanding the role of water and hydrogen.
It was a total fluke accident. We were in a very remote part of Iceland, and I would be hard-pressed to imagine there would be more than two cars on the road at any given time. We had lunch and we were heading back, and there was a caravan of cars right in front of us. My colleague who was driving decided to pass them. We were doing it at high speed when one of the cars from the caravan pulled out into us. The whole thing just kind of rolled over three times. I had been taking photographs out the back window and hadn’t put my seat belt on. I ended up being ejected. I was super lucky to have survived it.
I had to be airlifted out of Iceland. There was not a single orthopedist in the country who could deal with the level of trauma I had experienced. I was pumped full of morphine lying there for three days before they were able to airlift me out. I don’t really remember a whole lot of it. I spent much of the last fall in a wheelchair recovering and doing lots of physical therapy.
But I hope to be able to go back. My colleague from Iceland was able to send us most of the rocks we had collected. So we have the samples, and we are working on them now and hope to be able to go back and collect a few more to finish out the project.
I think I would feel some form of PTSD working on those rocks. I wouldn’t want anything to do with them.
Well, the accident itself is completely erased from my memory. My doctor tells me that is not uncommon in traumatic accidents like that. I just remember waking up in the ER, and obviously all the pain and discomfort afterward. But for a geologist, Iceland is a magical place. It looks like another world to me. Where we were doing fieldwork, it was mostly dark basaltic rock, and it was like a volcanic wonderland.
You’ve done a lot of work on geochronology — determining the age of rocks. How has this changed our view of how planets are made?
The two thrusts that are important are trying to understand the origin of water, and understanding the timescales of the solar system — the chronology of when and how planets were starting to form. When did planets start to accrete, differentiate, melt, form a crust? In terms of the formation history of the solar system, there are three ways you can get a handle on that. There is the theoretical aspect, and astrophysical observations that constrain that, but the only way we can really get a handle on planetary formation at the level of precision we really want is through samples. The materials we have in our meteorite collection are one way to do it.
What do these rocks tell us about the solar system, and how we all got here? What do we learn about ourselves from them?
There’s a lot of commonality. The way we understand processes on Earth, you really can apply that to processes on other planets. And there are some fundamental differences, in terms of how much water there might have been, how the history may have diverged early on, in terms of loss of an early atmosphere, or impacts. As a case in point: Venus, Earth and Mars, if you think about them in the context of other solar systems, all three of these planets would fall in what we call the habitable zone. But they are so different! For Venus, certainly we don’t imagine there is any kind of life currently on that planet. For Mars, maybe there was in the past, and maybe still in the subsurface, but clearly it’s a different place than it used to be. History is different in these places. And in some ways that [history of life] has fundamentally changed the way these planets evolved over time.
The common thread is, if you have a sample of rock, you can pull it apart, atom by atom, and get into some really detailed information, which you can’t do by remote sensing. It’s telling how much more we know about the moon, for example, just by having so many rocks from there.
How often do you get to study newly fallen meteorites? How many of them are falling on us?
We get something like 100 tons of stuff falling on the Earth every single day. Spread over the entire planet, it’s not all that much if you think about it. Most of that is sand-size particles — tiny, tiny particles. Things that are about the size of a car, or van-size bolides, they hit a few times a year. Something the size of the Chelyabinsk meteor [which exploded over Russia in 2013], that’s a few times a year.
We just found a new meteorite that fell in Phoenix a couple months ago. It was really funny because it happened during one of these monsoon rainstorms, and I think people missed the fireball because they thought it was lightning. A person called us and said, “Hey, I found this rock in my backyard.” Most times when we get people contacting us, it’s not a meteorite. But this one was.
I imagine you get a lot of people calling about “meteowrongs.”
Yes! We had to suspend our meteorite ID program, because we just get so many requests. We don’t have enough people to really address it. We have a couple open-door events, and we encourage people to bring them by.
What is it like when they’re right? Or when you’re right? Have you ever walked onto the ice in Antarctica and found one?
It is the weirdest feeling in the world. As someone studies this and comes to understand a little bit about meteorites and why they are where they are, it is still amazing and just astounding. You are sitting on top of the ice, and it’s like, a space rock, wow. It’s surreal. Sometimes we find hundreds of them in an area the size of a football field. You realize there has to be some concentration of these because of how the ice flows and ablates in certain regions. But it’s still really kind of astounding when you actually find them. It’s magical, really.