The Mars 2020 mission addresses high-priority science goals for Mars exploration including learning more about the potential for life on Mars. Tech Briefs spoke with NASA’s Ken Williford, Mars 2020 Deputy Project Scientist, to learn more about the science capabilities of Perseverance.

Tech Briefs: Perseverance will be landing at Jezero Crater, where it will explore a site that is likely to have been habitable. How does this focus build on the “follow the water” theme that guided previous Mars Exploration missions?

Ken Williford: The focus for this mission is more complicated than that. It’s about determining evidence for habitability in a way that went beyond the simple “follow the water” for Spirit and Opportunity, where we were charged with just looking for a confirmation that there was water at all. And for Curiosity, we wanted to understand whether there was water but also how long that water had been there and the chemistry of that water. MSL [Mars Science Laboratory] was very successful doing that, starting in Yellowknife Bay early in the mission.

Tech Briefs: What are the four core objectives for Perseverance?

Williford: The first one is determining if life ever existed on Mars, the second one is astrobiology, the third is geology, and the fourth is preparing for human exploration.

The first one is understanding if there was one or more habitable environments in our exploration area using an approach very similar to what MSL did and asking those same questions: Were there different types of habitable environments? Were there different habitable sub-environments? Was the shore of the lake different from the middle of the lake where there’s some surface habitable environments? After asking all those questions, we take the next step in astrobiology and we are directly seeking signs of ancient life.

Perseverance will use its drill to core rock and soil samples that will be collected and stored on the Mars surface for future missions to retrieve and return to Earth. NASA and the European Space Agency are solidifying concepts for a Mars sample return mission.

We’re doing that very explicitly. Where MSL has some great capabilities to detect signs of life if it encountered some, it is not as much of a core focus of the mission. Curiosity’s mission was really about determining for the first time if there were habitable environments. With Mars 2020, we’re looking for evidence of past life in a way that I think hasn’t really been done since Viking.

Tech Briefs: Tell us about the sample collection process. What makes a sample scientifically compelling?

Williford: As you can imagine, there’s a lot to that. Right after we land, the first thing we’re going to do is try to understand in a basic sense what that environment was. Of course, we chose the site because we’re fairly sure that there was a lake there in the crater. We’re going to start to use the tools of field geology to understand right where we are.

If those rocks had water and then got hit with a giant rock from space, all that energy would have set up what we call impact-generated hydrothermal systems. The water would start to flow through fractures in the rocks and dissolve different minerals, setting up little micro environments where microbes could possibly survive. That’s a type of habitable environment. Given the environment, the conditions under which a rock formed, and given what we think we know based on the evidence we see, we’ll understand more about the history of that rock.

Many things happened to that rock in the billions of years since it was deposited and all of those things have an impact on that rock. All the processes have affected whether any signs of life could be preserved — whether they’re organic molecules or inorganic concentrations of biologically important elements, relationships between biologically important minerals, and other sorts of things.

Tech Briefs: So, the environment of Mars has a lot to do with the types and quality of samples.

Williford: The environment, of course, has to be habitable for there to be signs of life but then on top of that, we need to analyze and preserve those signs of life. And there are certain things working against us, like the harsh radiation environment. Mars lost its atmosphere a very long time ago, so the surface of Mars is much more hammered by cosmic rays and other kinds of radiation that tend to destroy signs of life.

The locations we choose are the ones that would have the best chance of preserving signs of ancient life. As we combine all those things, we look for little niches where habitability is maximized. We want to know that the rocks have been protected from some of the processes that destroy biosignatures and those spots make the best samples.

This image shows a concept model of NASA’s orbiting sample container, which will hold tubes of Martian rock and soil samples to be returned to Earth through a Mars sample return campaign. At right is the lid; at bottom left is a model of the sample-holding tube. The sample container will keep contents at less than about 86 °F (30 °C) to preserve the Mars material in its most natural state. (NASA/JPL-Caltech)

Mars sample return is much bigger than astrobiology. It gives us our first opportunity to scientifically choose samples from another planet and study them. Our only other opportunity to study pieces of extraterrestrial bodies came from either samples brought back from the Moon or meteorites that fell on Earth. It’s incredibly valuable to understand the evolution of the solar system in various ways.

A great thing about Mars is that it preserves rocks from a time when most of the rocks there have been destroyed. On Earth, it’s extremely rare to find rocks older than say, three and a half billion years. On Mars, many of the rocks on the surface are older than that including the rocks we’ll explore with Perseverance. That’s a time when life was starting to take hold on Earth. The ability to just understand what the geology was like and what the conditions were like on the surface of another terrestrial planet during that time is a huge bonus.

Tech Briefs: Perseverance will house science instruments for mineralogy, environmental measurement, and chemical measurement. How will they be used to investigate Mars’ geologic record?

Williford: There are two main instruments on the rover’s turret. PIXL is a micro-focused x-ray fluorescence spectrometer that sends an x-ray beam that can focus on rock features as small as a grain of salt and builds a map of the elemental composition of the rock.

On the other side of the turret, SHERLOC uses a UV laser of the same spot size (100 micrometers). It is a fluorescence and Raman spectrometer. It hits the surface with that laser across the same area that PIXL does. But now instead of measuring the elemental composition, it measures the light color composition. The molecules that are being measured can be minerals or organic matter.

SuperCAM uses laser-induced breakdown spectroscopy that involves shooting a laser at a rock that can be up to 7 meters away. It’s really a telescope with a laser beam coming out of the middle of it. That telescope mirror is collecting all the light that comes back. It has a spectrometer that provides elemental composition of the rock, similar to PIXL, but from a longer distance away.

Tech Briefs: What environmental information will Perseverance be looking for that could affect future human exploration of Mars?

Williford: In addition to the desire of the scientific community to just better understand the current weather on Mars, every time we get to the surface with weather instruments, it really improves our dataset about speeds and temperatures. That is very important to future human exploration and understanding those conditions.

Tech Briefs: What’s next for Mars exploration after this mission?

Williford: The next giant step is Mars sample return. We’re collecting samples that will be returned to Earth; however, none of those follow-up missions are officially fully funded yet. We still talk about it as a plan and a hope, but it’s being taken very seriously and NASA and ESA [European Space Agency] are cooperating on plans to get the samples back to Earth.


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This article first appeared in the June, 2020 issue of Tech Briefs Magazine.

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