Mary Beth Wilhelm is a planetary scientist and astrobiologist at NASA Ames Research Center in Mountain View California. She specializes in studying areas on Earth that have climates and landscapes similar to those found on Mars -- and that means some of the driest and most remote parts of the planet. She talked to us about what it's like to travel to the coldest and hottest places in the world where, in some cases, rain only falls once every decade.
What exactly does a planetary scientist do?
My work is a combination of fieldwork and lab work and a lot of writing. Way more writing than I ever expected going into the sciences. In my research, I'm mostly interested in searching for the signs of life on Mars. You could describe me as an astrobiologist -- understanding the origin of life on Earth and looking for it outside of Earth.
How can you find life on other planets by looking at Earth?
Basically I use these really Mars-like places on Earth as a testbed to understand how all of the components that make up life are preserved in those types of environments. One of the most Mars-like places is the Atacama Desert. You can look at dryness as a function of precipitation or you can look at it as the availability of water for life. In Yungay, a region in northern Chile, it only rains there once a decade, about 2 - 5 mm. Barely enough to even form a puddle. There's no plants, no lichens or mosses. I'm doing a study right now and don't even see evidence for activity of soil bacteria. Even the coastal city of Antofagasta in northern Chile, which is on the Pacific Ocean, is about 30 times dryer than the Mojave Desert.
How did it get so dry there?
It has to do with the Andes. They're tall and block the trade winds that go from the Atlantic towards the Pacific. Hot dry air descends on the desert. Offshore on the Pacific Ocean the currents come up from Antarctica they're cold and therefore the air doesn't pick up any moisture. It's' been like this for millions of years. It has been Mojave Desert-level dry for a hundred million years, a couple rain storms per year. And then it's been even drier, 100 times dryer than the Mojave, for 10 to 15 million years.
Has that changed at all as Earth's climate has changed?
As far as we can tell it's the same. Although that's not really what I study. There are people looking into that. It's hard to study because it only rains once a decade. It's never rained when I've been there. The last rainfall happened in 2015. The coastal cities were totally flooded. Nobody I worked with has been there when it rained. The last time before that was 2006.
[Editor's Note: Since the interview was conducted this has changed. According to an update from Wilhelm: "There was recently a big rainstorm that happened in northern Chile. Seventeen mm fell in the driest region, which is unusual and surprising. My collaborators and I will be working on new projects now to understand how the desert responds to the newly wet conditions."]
Do you study any other dry places?
I have recently visited a very windy region in Antarctica in the Gruber Mountains that is very dry. Antarctica is a big polar desert. I went there for the first time this year and there are really no plants. I can't explain how much ice there is, it's incredible. There's endless ice.
The driest region in Antarctica is called the McMurdo Dry Valleys. I hope to visit there someday. There is a high-elevation offshoot of the Dry Valleys called University Valley, which is especially dry because it's so cold. University Valley is the cold analog to Yungay. It's so dry because it only gets above freezing for a few hours every year. Liquid never forms. In these types of places it's really hard to be a microorganism.
How do we know these are analogs to Mars?
Analog is a word that's so poorly defined because people use it in different ways. The Atacama is an analog because of the prolonged dryness all these weird and rare salts have accumulated. For example, there is perchlorate. It's one of those weird salts we've found on Mars that has this weird property: when the humidity gets high enough liquid water can form inside the salt.
So what happens to life when the desert starts to dry out?
First you lose the plants, then you lose lichens, which are a symbiotic relationship between an algae and a fungus. Then you lose colonies of organisms that inhabit rock: there are two types -- endoliths inside rocks and hypoliths that live under rocks. Finally, you have organisms that live in deliquescent minerals in which water vapor in the air can become liquid. We see organisms that are barely hanging on in the Atacama in the driest regions by using these salt habitats. Organisms are surviving inside of salts that can take water vapor and turn it into liquid water.
How do they eat?
They're photosynthesizers. The limiting factor there is water. The microorganisms are going to go to the places in which liquid water hangs around the longest. There's a progressive loss of ecosystems as the climate dries. In the soils in the driest parts of the desert we are not finding evidence for them being active, just evidence of their dead bodies that pile up, preserved by the dryness. We're still trying to understand it.
Do you think there are microbial dead bodies piled up on Mars?
We know that Mars is really dry. It's 100 to 1,000 times dryer than the driest part of the Atacama. We know that ancient Mars was once much more habitable, it had shallow seas, a thicker atmosphere, and was warmer a few billion years ago. It was a pretty nice place to be a microbe. Then it dried out over time and turned into a desert. So if we're lucky maybe we can find these refuges for life. Mars is a pretty unfriendly environment right now.
"The more time I spend in the Atacama the more I think there's some pretty significant challenges for life hanging on in the Martian surface."
The more time I spend in the Atacama the more I think there's some pretty significant challenges for life hanging on in the Martian surface. It's not exactly good news, but it informs how we might look for modern life.
My research is also focused on understanding what happens to all those chemical compounds that make up life after it dies. How does the desert in its dry state degrade them. It turns out they're very well preserved. It's salty and dry. That's a natural mummification process. So part of my job is digging giant holes to uncover ancient sediments that might have preserved those molecular fossils.
Why do we care about life on Mars?
It's interesting philosophically. Are we alone in the universe? Is life common to the places that can support it or is life in generally rare? From a scientific perspective it would be interesting if we found life, would it be related to Earth life? Would it be totally different? There would be future medical applications, understanding how evolution would operate in that environment, is there a second genesis for life? It would be interesting to find out what it looks like and what is it made out of? How does that chemistry work? It would be totally alien to us.
On Earth, there are places that we can use as our testbed for Mars. It's not a perfect analogy but it's a lot easier then going 100 million miles away.
But we expect chemistry to work the same. The analogy that I'm studying is the dryness and what happens to carbon after it's been baked in the sun, dried out, and exposed to salt for millions of years. We expect the chemical processes to hold up. We try to focus in and control for the parts that are Mars-like.
What kind of gear do you need to bring with you when you go to the desert looking for dead microbes?
It's not so complicated. The hard part about it is, because there's not a lot of stuff growing there, it's really easy to contaminate the soil. So I have to be wearing a white bunny suit to protect the environment from me. Humans are like Pig Pen from Charlie Brown -- we're constantly sloughing off bacteria and organic molecules keep our mess from falling into the soil. Forensic studies say humans emit a million particles per hour. That's a lot of stuff coming off of us constantly.
So I wear clean room suit, goggles, a mask, and sterilized gloves. I put my glass jars in the oven at 550°C [1022°F] overnight. And what that does is bake off every organic compound to keep it super clean. Then I pack them up. I'm more worried about them breaking and getting contaminated after that. Coming back into the country with 200 lbs of dirt and jars crossing three borders is always a small scene. But it's just ancient dirt with nothing living inside of it.
Do you ever have any trouble getting through customs with it?
Border crossing people are pretty interested in it. I show all of my credentials, and products, and all of my letters. But it's always at 5 AM, and I'm groggy trying to explain science. I'm a girl in my 20s wearing my Ugg boots carrying pounds of dirt.
How hot is it there? It must be oppressive in that bunny suit.
When I go it's usually summer. So it's been in the 100s or the 90s. I'm pretty sweaty. It gets pretty toasty. But the bunny suit is good sunscreen.
How do you know where to dig?
I definitely have tried to leverage where other people have done sampling because I want results that are reproducible and comparable. People have been studying the Atacama for a few decades. So if I find a weird or cool result I can put it into context.
How can you make discoveries when you're looking somewhere that other people have already been?
There's so much to be done everybody has a slightly different expertise. People who have done work before me have looked for different biomarkers or what the soil is made out of. It's like standing on the shoulders of people who have come before.
What are the popular locations?
The most popular one is the driest site. There are studies done there a couple decades ago using that to reinterpret the Viking lander result on Mars from 1976 and '77. They took soil from that region to try and understand what they've seen on Mars better.
The Atacama has this really cool property where if you draw a line from North to South -- from the driest part of the desert towards Santiago in the South it gets progressively wetter. It goes from one rain per decade to one rain per year. That changes the DNA of the organisms you find there. The wind does a pretty good job of transporting material around -- if you have bacteria stuck to a dust grain that's how thing's get redistributed.
Do you sleep out in the desert when you're sampling there?
We camp a few miles away from the site. It's not that exotic, it's only an hour away from the town. And it's been an active mining site for more than 100 years in Chile. Now they're mining copper and salt.
When you fly into the town it's mostly mining companies. Scientists stick out in the airport. It's mostly men wearing designer clothes and hiking shoes.
How big is your team?
I went out there for the first time with three people but subsequent years there's a big NASA project that got funded to do rover testing in that area. So this last year we had 40 people. They have a company that supports everyone and help cook. It's nice to have that ground support when you have 40 engineers.
Sometimes the camp is quite populated, but when I go out to do the science I just take one person to help with manual labor. Drilling and digging. It takes a while because they ground is like concrete. Maybe even a little bit harder then frozen ground. We've used some drills that are meant for permafrost and we've destroyed four of them.
I've bent so many bits the easiest thing is to go and buy drills you use for your wall and then get a chisel to loosen the ground and then shovel it. It's not the most elegant approach. Using a backhoe has been a dream of mine. All the cool stuff is only 2 meters [6.5 feet] underground. The preservation is so good in that area you can find 2 million-year-old fragments of plants with really weird root systems. It's amazing that it's still so intact after all this time has passed. But getting down that far is not trivial -- especially when it's 100 degrees. I've worn my fitbit when I drill it's a 1,000 calorie workout.
How do you know how far to dig?
We know we want to get down at least a meter and a half. There's a thick salt layer that acts as a barrier to water. During the rare rain event water doesn't get below that salt layer. So we want to get below it because we know that stuff has been cut off of water for 2 million years.
What do you do once you're done digging?
You don't want to wear the suit when you're digging. So the next day you've come back after taking a camp shower. You put the suit on and get in the hole. I use drill bits I've gotten from Home Depot. It's a one time use. I will remove 2 feet of the wall in the hole to access a clean site we haven't put our fingers all over.
Most of what's there is all chemical. At that point I use another clean drill bit or clean spoon and scoop loosened material into a jar. Then we put it in ice or in a freezer. Just so nothing degrades. It's unlikely it will because it's so dry. But keeping things cold makes the chance that chemistry happens lower. We would probably be fine if we didn't but it's just a precaution. It's the standard for sampling microbes to delay growth or prevent anything from getting eaten or changed.
It's dry and dead but I don't want to take that risk. It's triple sealed. I put the jar in a bag in another bag and then in the freezer. That does a good job keeping the moisture out.
It's not the glamorous part but it's the important part. If you skimp on those details then you invest all that time and money and have contaminated the sample. You've invested months of effort and money to have a bad sample.
How do you know when you have enough dirt?
I pick out which samples are the most interesting based on if I see anything weird in them or if I have a nice distribution of throughout the pit. I want to have backup or extra if another scientist comes along and wants a sample of something interesting. It takes four or five days of work. As you sample the depth you're going farther back in time. So I also look at how the modern day stuff on the surface compares. Maybe you don't study everything in the lab but you have backup in the fridge.
What is life like at camp?
It's a lot like Girl Scout camp. I'm super glad my mom made me do that as a kid. A lot of people are not used to being uncomfortable or not getting great sleep or eating great food. It helps to be relaxed. At night time we play cards. When I went in February we'd been testing and building a rover that can do similar analyses to what I'm doing in the lab. We take the rover out to the desert and try to break it. We have software engineers, hardware engineers, and scientists from all different backgrounds. And the rover is capable of drilling too. The team has adopted my sampling technique -- wearing the cleanroom suits. We take the rover to the site. Everybody will suit up and drive the rover away from where the people are standing at mission control area.
It's a pretty slow process, it drills down to a certain level and eventually the goal is the dirt will be caught and the instruments will search for more complex biomarkers then what Curiosity [the rover currently on Mars] is doing. Next year we'll have the instruments on the back of the rover and we can go from dirt to data.
You can imagine some people have never been camping before and put in this environment. It's hot and really dry. Trying to do something really complicated and technical in an uncomfortable environment is rough. One night we worked from 9 am to until midnight. It's good to have a team that's patient and kind and willing to be uncomfortable.
Do you ever have arguments or trouble getting along? I'd imagine it's not easy since you've never met a lot of these people before.
Field work is interesting for the science and also what plays out for people's personalities. It makes me wonder what it will be like one day to go to Mars.
The Antarctic is the perfect testbed. It's remote there's a real sense of danger. If something bad happens you're a long way from help. When I went down there I experienced that psychologically. You do everything more slowly. Even spraining your ankle or hitting your head is more dangerous.
And there's the isolation. There's no internet. You're eating freeze dried food. How much you change, how much my personality changed to be accommodating to the environment... You're never warm. You're never comfortable. I was the only woman with 10 other men. The thing I missed the most was female camaraderie. I had to have the moment by myself.
But it's different what happens when people go to extreme places and you're not just going for fun. You're trying to accomplish a task. And it's not easy. Watching engineers trying to troubleshoot software in the Atacama wearing their clothes they wear to work every day -- it's a perfect testbed to start studying what it might be like some day going to Mars.
People are chosen because of their skill set not because of their tolerance to discomfort.
Where the conflict resolution comes is the interesting part. Certain people emerge as mediators. And you have to learn how different people tolerate stress and conflict. It's like preschool. It's not complicated. It's an extension of the professional environment so it's still work. Even though you're camping next to each other.
What are you studying in Antarctica?
"The ecosystems [in Antarctica] resemble early Earth. It's totally otherworldly. You would think it's another planet. It's looking back in time and thinking about how life might colonize an icy moon."
I went with a trip organized by Dale Anderson at the SETI institute. He dives in Antarctica. We melted a hole in a lake that's frozen on the top and he puts his entire body in a lake.
This lake we're studying is an analog for early Earth. Only simple organisms can survive there. It's cut off from the atmosphere and fed by glacier water melting. There's no algae or fish -- not even diatoms. The ecosystems resemble early Earth. It's totally otherworldly. You would think it's another planet. It's looking back in time and thinking about how life might colonize an icy moon. I've never seen anything like it.
Is it dry there?
The lake is slowly drying up. Mounds of simple organisms get instantly freeze dried when they get exposed to the surface. I'm studying the preservation process and trying to understand the molecular components. How they might get preserved so we might understand what biomarkers we could find on the martian surface.
We went to Lake Untersee. If you draw a line straight down from Cape Town it's 100 miles inland on the continent of Antarctica. It's super windy. There's not a lot of snow and when it does precipitate, it's a sublimation-driven system, the snow and ice gets turned into vapor very quickly because of the wind. There's a nearby valley that used to be connected and as the water level dropped the lake dried up really fast. You can imagine that all those organisms living at the bottom were instantly freeze dried. It's like walking around the bottom of the old lake. Their structure is preserved. I don't have any results yet.
Who else was on your team?
We went down with the Russians. It was a totally unusual way as an American to go the Antarctic. We go with a company called Antarctic Logistics Expeditions. You board Aleutian jets and they have them outfitted to land on the ice. It's a six hour flight to Novo Station [the Russian Antarctic research station Novolazarevskaya]. It's in the Eastern part. When I got on the plane it was 10 of us on our team and 65 Russian men. Plus a couple of Canadian pilots.
The Russians were a mix of geophysicists and guys that operate the machinery to clean the runway -- white collar and blue collar people. Some of them spend a few months down there and some spend a year or more. There are really interesting personalities attracted to that job.
Down at McMurdo [the US Antarctic research station] I've heard that's it's caused conflict in the past -- the division of people. I was anticipating that but it wasn't like that at all.
What is it like to be surrounded by only men for that long in such isolation?
You just blend in. Keep your head down. There were no problems. Dale Anderson is such a veteran that I felt very safe. I've never been on a trip that was so well organized and so easy. He had a handle and control of the situation. I spent 2 months down there and I was less tired than I am after 10 days in the Atacama. We had down time so you never feel overloaded.
How do you travel around Antarctica? Do you stay at the station or do you have to travel out to the research site?
They have these big ice runways and it's really weird going from Cape Town to Antarctica. We spent a few days at Novo Station packing up all our gear. We drove 100 miles on these big sleds pulled by Pisten Bullies. They look like tanks. They can cross the big cravasses that form in the ice. So it's a series of tanks, one tank pulling a huge salad with propane and all of our fuel and then on the back with a little cabin where we sat. It's a 9 hour drive in this tank/sled situation to go 100 miles. I listened to my whole iPod twice.
Then we camp out there. That was interesting. The temperatures were pretty good for Antarctica -- they were just barely below freezing. I was really cold for the first two weeks but then your body adapts. As a rookie there's a huge learning curve. The one perk of being the only woman is I get my own tent. Because of the Antarctic Treaty you have to pack out all your waste. I peed in a bottle for two months. There was a poop tent. They have special containers and nothing is left behind. "Stuff" management in Antarctica is such a pain it's incredible that it's not polluted. There's no roads and it's never been inhabited by people so there's a great effort to keep it that way.
What does the research site look like there?
We had little snowmobiles that we would drive around the lake. We melted a huge hole in the ice, which took a couple days. Dale would dive, take samples, and bring them topside, I would seal them so I could study the stuff that's still alive at the bottom of the lake and the 10,000-year-old stuff that's been freeze dried on the surface.
It's not really well studied. People usually study stuff that's still alive or been dead for a long time and been degraded so this is a cool little niche.
Science research and funding isn't being favored by our government these days -- do you have any suggestions about how everyday folks can help support science?
It's really important to focus on getting kids interested. I benefited from outreach and education that came out of NASA. I grew up in the Bay Area, close to a NASA center. Getting kids excited about science is so important. It really doesn't matter when they're young what the science is. Just getting them to be engaged lays the groundwork for them to pursue it later in their lives. And whether they pursue the career or not, everybody at some level is curious about nature and about science. People who are talented should have the opportunity to pursue it as a career. NASA does a great job with kids, it's the gateway drug for careers in science or engineering fields.
I started working here when I was in high school. I worked part time for a scientist that was studying Mars. She had 20,000 images for me to look through from a Mars satellite. I would leave school, come here, and help her look through them. I never left.
Not all science is done in a lab by guys in white coats staring into microscopes. Lots of discoveries require brave men and women to put their boots on the ground and get down and dirty in dangerous environments. Every month we'll profile one of these field scientists, tell you how they do their job, and explain the science behind what they do. If there's a scientist or field of science you're dying to hear more about shoot us an email or a tweet: erin at erinbiba dot com, @erinbiba
Photos courtesy Mary Beth Wilhelm