NASA's JPL Caltech science team has spent years analyzing and researching data about Mars. The hope is that there is life beneath the Red Planet's surface and that this will further scientists' understanding of planetary evolution and, ultimately, of our galaxy.
In an interview with Interesting Engineering, Jesse Tarnas, a planetary scientist at JPL Caltech and NASA post-doctoral fellow, discussed where we currently are in the search for life on Mars, the future of Martian habitation, and what that means for us here on Earth.
Tarnas explained that part of his motivation comes from, "The idea of us living in a future where humans are collectively inhabiting Earth in a much more honorable and sustainable way." He believes that many of the ways this could be possible, and how we could learn to do so, come from exploring space, and from learning to inhabit other planets, like Mars.
How NASA's planetary scientists figure out if Mars was, and is, habitable
Tarnas is part of the Mars Rover Perseverance 2020 team that looks at the rover's data as it comes in. The team uses a blend of the rover's current data, orbital data gathered from planetary satellites floating above in orbit, and data from past rovers and landers to try and evaluate different aspects of the planet's history and the potential of using space resources.
To gather that data, the team works hard to optimize a solution for exploration that gets the maximum scientific benefit out of the rover, for example, by planning out the rover's next ports of call.
For instance, the Perseverance rover is currently in the Jezero Crater on Mars, looking for as diverse a rock sample as possible to bring to Earth for further analysis, which the team is hoping will be some time in the 2030s. The hope is that the samples will enhance our understanding of the kind of environments the crater supported in the past, as well as its potential for habitability, and whether or not those rocks could host biosignatures that give scientific evidence of past or present life.
Looking further beneath Mars' surface, Tarnas' research also involves working on the science behind the Mars subsurface, and the potential for life on the Martian subsurface if there's ground water. He pointed out that he's not looking for fossilized life but life that could currently exist there today if there's groundwater.
So, why is it important to know if there has been life on Mars?
"It's really interesting from the standpoint of planetary evolution in general," explained Tarnas.
On Earth, the fact that we have living organisms has fundamentally affected the way the planet has evolved, and this, in turn, has impacted Earth's climate and atmospheric composition, among other factors.
There are lots of different directions that planetary evolution can take if organisms are present where planets are habitable. "In fact, there are potentially many habitable objects in our solar system — largely in the subsurfaces of those objects — and so far, Earth is the only object with a habitable surface environment that we know of," said Tarnas.
It’s time to start my search for ancient microbial life. I’m heading south to survey some of the oldest geologic features of Jezero Crater. My team will then work to bring my auto-navigation and sample systems online before I start collecting rock cores. https://t.co/gHYwiqqLmW pic.twitter.com/aykaGbkd4q— NASA's Perseverance Mars Rover (@NASAPersevere) June 9, 2021
We already know that there were past environments on Mars that could have harbored life, so really the question is, "Were they inhabited?" said Tarnas.
Answering that question could help us to determine the probability that life exists on planets where similar environmental conditions occur. This can then help researchers to determine the conditions necessary for life to exist in other worlds and the mechanisms by which biochemical systems involving rocks, water, and life interact together.
This would allow researchers to fundamentally map out a planet's evolution, depending on what types of gases it's producing, for instance.
Is it possible to inhabit the Moon or Mars?
"I definitely think it's possible," per Tarnas.
He continued by explaining that "We've had people living up on the ISS (International Space Station) now for decades. That's a controlled environment where you're constantly exposed to some pretty harsh conditions in space, but they're able to pull off doing it."
However, he also pointed out that there are constant resupplies sent up to the ISS from Earth. The more we can figure out ways to generate resources in situ, and to use the materials from a planetary surface, the less necessary sending supplies from Earth becomes.
"The ISS has no on-site resources that the team can use, but if you're on the Lunar or Mars surface, there are potential creative ways you can come up with to extract water, bulk materials, and to construct habitats," Tarnas assured us.
For Tarnas, one of the things that really inspires him to work in this field is finding ways for humans to inhabit planets other than Earth. He is also motivated to do so in a way that's based on the very nature of space exploration: Being frugal with your resources without wasting anything.
"You can't just depend on extracting more resources from your environment, you have to make sure you're reusing everything to the greatest extent possible, and I think there are a lot of lessons that can be learned from that process," he stated.
Tarnas hopes that ethics can then be brought back to Earth to help us inhabit this planet in a more efficient and sustainable way. Exploring ways of sustaining life on Mars will eventually feed back into finding ways to sustain life on Earth.
Water is crucial for humans to be able to inhabit Mars
Water would not only be necessary for humans to be able to drink and breathe on a future Mars base, but it would also be used to develop fuel for the rockets that will land and launch from the base. The key is finding enough water on the planet for these uses.
There are a few different ways to do so based on the available data from Mars. Tarnas explains that we can either try and draw water from regoliths and hydrated minerals, which may contain a great deal of water in the form of molecules bound to other minerals in the soil, or we can try and collect it from nearby frozen ice-cements, some of which may be as much as 40% water.
The key next step is to search for deep groundwater on Mars and explore the subsurface. Radar including @RIMFAX2020 on @NASAPersevere is doing this now. Dedicated missions to study underground Mars would unlock its full science potential. https://t.co/qh1ik0l0s2— Jesse Tarnas (@jdtarnas) April 23, 2021
However, before jumping in and choosing a focus for the first missions, there are many considerations to be made. There are a number of restrictions NASA and other space agencies have to adhere to, such as not taking too many big risks with as pricey a piece of equipment as the Perseverance rover.
Mars rovers have mobility limitations, but that doesn't deter Tarnas and the team. "That's what games are," explained Tarnas. "We have these restraints and then we have to figure out a way to win the game given the restraints. So it's just another rule that the game has that makes it exciting and interesting. But it does make you realize how much benefit you can get from mobile human exploration on Mars and how much exploration from Mars can be done via helicopters like the Ingenuity."
Ultimately, having humans inhabit Mars would hugely add to the exploration of the planet, just like we are able to do here on Earth.
The future of inhabiting Mars and other planets
"I think it's very exciting to think of a future where humans do become multi-planetary, where we understand the impact that life has on objects and planets inside and outside of the solar system," said Tarnas.
"I'm not an advocate for, 'We've learnt everything we can on Earth, we've got to go explore these other planets; or we've already messed up Earth, so we've got to live on these other planets,'" he explained. "I really think that both the exploration part and the inhabiting part of Earth and other planets has to be a synergistic effort, and it will only succeed as a synergistic effort."