Mars was not always the cold, barren world we see today. Billions of years ago, rivers flowed across its surface, lake basins were filled with water, and water interacted with rocks, possibly creating conditions favorable for the emergence of life. What happened to transform this world so dramatically? Could studying Mars tell us something about the future of our own planet?
Planetary science is a field of science that has made significant advances in recent years and seeks to answer these and many other questions: How do planets form and evolve? What geological, physical and chemical processes can lead to the emergence of conditions favorable for life? Planetary scientist Dr. Bethany Ehlmann, a former professor at the California Institute of Technology (Caltech), now leads a research center at the University of Colorado: the Laboratory for Atmospheric and Space Physics (LASP). She has spent many years studying the geology of Mars and has played a key role in numerous NASA missions, including those involving the Spirit and Opportunity rovers sent to explore the Red Planet. In addition to studying planets in our Solar System, Dr. Ehlmann is particularly interested in tracing the history of chemical processes involving water, using spectroscopy as a tool to detect minerals and ices.
During the STARMUS VIII festival on the Spanish island of Tenerife, the planetary scientist spoke to Armenpress about what Mars can teach us about Earth’s past and future, whether humans will ever be able to make the Red Planet their second home, whether water can still be found on its surface, and, ultimately, why exploring other worlds is important in helping answer one of humanity’s oldest questions: Are we alone in the universe?
Armenpress: I’d like to start by talking about planetary science as a relatively new field. Why is it important, both for science and for space exploration?
Dr. Bethany Ehlmann: My field of planetary science focuses on the planets in our Solar System, and we’re also beginning to discover planets outside our Solar System.
One of the key questions is simply: How do planets work? How exactly did they form? Can we predict how they’re going to evolve over billions of years? And can we figure out which planets are good for potentially sustaining life?
These are some of the most fundamental questions. Another is: Is there life on any of the planets in our Solar System or beyond?
Much of your research focuses on Mars and its past. When you look at Mars, do you see a possible future for Earth? We know that Mars was once very different, with an atmosphere and liquid water on its surface. Can studying what happened to Mars tell us something about Earth’s future?
Mars today is cold and dry and has a very, very thin atmosphere. But as we look at the rock record from the past, we see that there were lakes and rivers and hydrothermal systems, and these are recorded in the minerals and textures of the rocks.
The big question is: what happened, and why? And what does that tell us about how a planet’s climate can change, and how planets keep water in habitable conditions or not? How do they keep habitats for life or not?
I don’t know that Earth will experience the same thing as Mars, at least not any time in the near future. Maybe several billion years from now. But what we think happened on Mars is that it lost some of its atmosphere. It’s smaller, and so its gravity holds onto the atmosphere less strongly. It lost some atmosphere to space, but it also lost some of its atmosphere through water and CO2 and other things in the atmosphere — oxygen, to the extent that there is a tiny bit on Mars — reacting with rocks. This happens on Earth all the time. That’s why we have soils, actually, and not just a bunch of rocks on our surface.
But on Mars, once that reaction happened, it took some gases and water from the atmosphere and brought them down into the soils and rocks. But then volcanic activity slowed, and there was nothing to replenish the atmosphere. So we think that geology might be important in determining, over the long term, whether a planet can have an atmosphere.
On Earth, we have plate tectonics that cycles plates down into the mantle, and then volatiles like water and CO2 come out again via volcanoes. But on Mars, maybe there are still volcanoes, but they don’t go off very often.
Did Mars also lose its atmosphere and water because its core cooled down and its magnetic field weakened? Is that what ultimately led to the planet’s transformation?
One of the questions I would say about rocky planets with atmospheres generally is whether the magnetic field is important for protecting the planet and helping it keep an atmosphere, or whether, in some cases, the magnetic field can actually help the atmosphere escape. I think the jury’s still out. I think we need to study magnetic fields around Earth more, in fact. Get some more measurements of what’s happening around Earth, and also some more measurements of what’s happening at Mars and Venus, as these are the only three examples in our solar system where we have rocky planets with atmospheres.
I have colleagues who are pretty convinced that, with the right radio telescope measurements, they might be able to see magnetic fields around exoplanets, around other stars. So maybe we’ll get some more data points that way on the question. But I think what is sure is that Mars’s geologic activity — so volcanic activity that releases gases into the atmosphere — things like, you know, earthquakes or Marsquakes, where the ground is shaking — has slowed through time.
There’s less of that happening now than there was, you know, 2 or 3 billion years ago, halfway through Mars’s history. But yet Mars is still active today. We know from the InSight lander that there are Marsquakes, which probably means there’s magma moving underground, but not as much as there once was. And I think what we’re learning is how that geological cycle over a very long time helps set whether a planet could be a habitat for life or not.
We sometimes look at Mars and wonder whether it could one day become a second home for humanity if something happened to Earth. Elon Musk and others have proposed colonizing Mars, even suggesting that we could somehow restore its atmosphere. But how realistic are these ideas? Are they science or still largely science fiction?
Well, so to be clear, I’m a big fan of human exploration of the solar system, especially on the Moon and Mars. And I would love us to have scientific research colonies on the Moon and Mars. That’s incredibly exciting to me as a geologist. But I think the idea that Mars is going to be Earth 2.0 is science fiction.
One of the aspects is that one could, on Mars, live within structures. So you could imagine a world where the air was brought, it filled these structures, and there was farming and vegetation grown inside the structures. But you have to stay in the structures.
There’s not enough of the feedstock on Mars for there to be this, like, massive terraforming or anything that would change the planet into Earth. But you could create habitats and live within them. And the Mars dirt would be okay for growing crops.
NASA’s Perseverance rover was traveling in the ancient Neretva Vallis river channel when it captured this view of an area of scientific interest named “Bright Angel”
If you could uncover one missing chapter in Mars’s history, one thing we still don’t know about the planet, what would you most want to discover?
I really want to know whether there’s water on Mars today. And there are two places we need to look. One is we need to look in some of the ice that’s kind of at the mid-latitudes of the planet and see whether there’s small amounts of water that form within it when sunlight hits it and in and around dust grains.
And I think the second place we need to look is underground, because from that ice there could be water underground. we haven’t set instruments with the ability to look yet. We’re really just in the beginning stages of being able to explore Mars as a planet.
Much of your research also focuses on water on other planets. Why is water so important in planetary science? Is it mainly because its presence could point to the possibility of life beyond Earth?
Water is important for so many reasons.
It’s definitely a precursor to life. You have to have the chemistry before you have the biochemistry. We are ourselves mostly water, so the kind of chemistry that supports life involves making organic carbon and other materials with water. So tracing the history of water means tracing the origins of the ingredients for life, the potential for habitats for life, and maybe even finding life.
We rely heavily on robotic missions to explore other planets, partly because human spaceflight is still risky. But is there something a human explorer could observe, recognize or discover on another planet that a robotic mission might miss?
As good as robots and sort of AI perhaps are, there’s an element of human exploration that humans are still so much faster than robots in exploring and in connecting the landscape to prior knowledge, to noticing anomalies, to being able to, you know, even just deal with situations that we don’t think about very much.
But what if the rock is slightly irregular or rough? Right now the robots that we bring can’t operate than some of the rover equipment on it. It’s too rough. So as interesting as it might be, we have to leave it and drive on.
Whereas with the human ability to manipulate with our hands and also with tools, there’s an ability to interact with the environment with a greater degree of flexibility and back and forth. And so that is one reason I’m a big fan of human exploration on the Moon and Mars is that it speeds up the cycle of exploration.
Your research focuses primarily on the planets in our Solar System, but have you also explored data on exoplanets? If so, what are the three strangest or most fascinating exoplanets you have come across?
I’m not sure I could give the three strangest exoplanets because I don’t spend too much of my time thinking about exoplanets.
I can say that what’s most exciting to me as a geologist is that for certain exoplanets we’re now able to see their surfaces, even with the James Webb Telescope using spectra. And these many many hundreds, if not thousands, of wavelengths are important because then you can start to see, well, what is the surface made out of? And then what does that type of rock tell you about the history of the planet and what kind of atmosphere might have come out of those kinds of lavas? And it’s all getting very exciting as these are transformed from points of light to bodies that we can start to understand how and why they work the way they do.
And why is it important to keep asking questions?
I think there’s something very fundamental in humans about asking the big questions of, like, how did we get here and are we alone? And asking these kind of scientific questions is just a way of taking small baby steps toward answering those bigger questions.
What do you consider to be the biggest scientific achievement of the 21st century?
I’d probably say the biggest scientific achievement of the 21st century to be in the realm of DNA sequencing. Rapid sequencing and the ability to manipulate DNA are probably what I would pick.
The Armenpress coverage of the STARMUS festival is supported by Team Telecom Armenia.