I work remotely — on Mars

Nicolas Randazzo is proud of his unusual title: Mars 2020 Perseverance rover postdoctoral scientist. He’s based at the University of Alberta in Edmonton, Canada, where he works with meteorite geologist Chris Herd. But Randazzo also collaborates with NASA’s Mars rover science team at the Jet Propulsion Laboratory (JPL) in Pasadena, California, and the Johnson Space Center (JSC) in Houston, Texas. Team members work together to collect and analyse remote visual and chemical data sent to Earth by the car-sized Perseverance rover, which landed in Jezero crater on 18 February 2021. He dreams of the day when samples of rocks and soil can be physically returned to Earth, allowing for more-detailed analysis to address questions including whether mineral samples hold evidence of life.

To prepare for the sample return, Randazzo also works on NASA’s analogue, or simulation, research. He is part of a team that orchestrates sample collection from Martian-like habitats on Earth, such as the Pilbara desert in Australia, to help refine understanding of how precious Mars samples should be handled in the future. Randazzo tells Nature about working with material from another planet and how he is planning for his career’s future, knowing that decades could pass before Martian samples get shipped back to Earth.

How does Perseverance help us to understand the Martian surface?

Planning for life on Mars

Every day, we’re moving along with the rover, exploring new environments and samples. I’m involved in studying Martian chemistry and sedimentology to better understand the ancient water flows and climate of the red planet, and gain clues about whether it held ancient life. The rover’s multiple instruments enable multidisciplinary exploration. The PIXL instrument uses X-ray fluorescence to determine the microscopic make-up of rocks. High-resolution cameras MastCam-Z and Supercam take zoomed in and out views of the Martian surface, atmosphere, rocks and soils. SHERLOC uses cameras, spectrometers and a laser to search for organic molecules and minerals altered by water. Wonderful high-resolution cameras allow us to look at geology in context and ask simple questions, such as, ‘Why is this mineral white or this mineral red?’ Wonderful people on the team stitch images together to make 3D models. You can put on a virtual-reality headset and simulate touching an outcrop of rock. There are a lot of great instruments, and a lot we can learn, but it’s always a team effort.

What have you found recently?

An exciting find a few months ago was a surface covered in leopard-like spots. We discovered that their chemistry indicates the possibility of redox reactions — chemical reactions, involving the exchange of electrons, that are common and vital to life functions such as photosynthesis and respiration, but also to abiotic processes that are nothing to do with life, like corrosion or rusting. We also found a chemical signature suggestive of vivianite, a mineral often found in fossil shells, and other compounds that could suggest there is life — or was life. But we can’t say for sure. There are also potential non-life explanations. We don’t want to jump the gun, as happened in 1996 with the Allan Hills meteorite, which looked as if it contained worm-like fossils. Then-US president Bill Clinton announced in a speech that NASA had found possible evidence for Martian life. It turned out that the rock contained structures created by abiotic processes.

Why do we need to bring Martian samples back to Earth?

As wonderful as Perseverance’s instruments are, nothing beats actually having samples here, to run analyses in laboratories, with higher precision. For example, none of the instruments on Mars are doing stable isotope analyses, which could tell us more about how warm and wet Mars was in the past, using oxygen and carbon isotopes. To look at isotopes of carbon, oxygen, hydrogen, sulfur and strontium, you must bring rocks here. The same goes for radiometric dating to estimate when a rock was deposited. We can’t do that work on Mars. Bringing samples home is infinitely more valuable than anything remote science can tell us.

When will a mission bring samples back?

There is more than a bit of uncertainty about that. The original plan for Mars Sample Return was the early 2030s. Now it seems it’s been pushed to the 2040s and it’s going to be more expensive than originally predicted. Plus, there is competition with other missions. It’s always a balance between finances and time, and there’s been an open call to industry partners to see if they’re willing to invest in making it happen.

How do you plan for your future work, given that sample return could be 20 years away?

Is there life on Mars? What a cave on Earth can teach us

A lot of research questions come up minute-by-minute, as we see the remote samples. We’ll be driving the rover, find something interesting, scrape the rock’s surface to get a sample and then see what it looks like geologically and chemically by doing a PIXL scan. Then, if it’s deemed worthwhile, the rover collects a physical sample that is stored in a titanium tube. Some of the sample tubes are stored inside the rover and, just in case of catastrophic losses, back-up samples are also placed on the Martian ground in a cache at the Three Forks sample depot in Jezero Crater.

Much of the Perseverance work here on Earth focuses on: how do we handle samples if and when we get them back? What’s the order of analyses we’re going to do?

In some ways, there are advantages to the samples’ return being far into the future. Right now, we can detect sulfur compounds at the parts per billion or parts per trillion level — something that, decades ago, was almost unimaginable. So, 10–15 years from now, there will be more-precise techniques.

A lot of careers will open up because of materials brought back. In 2022, scientists opened a tube from the 1972 Apollo 17 mission to the Moon. I had the opportunity to hold that tube in my hands during a recent tour of the Apollo lab at the JSC. The Apollo missions came back more than 50 years ago, but there are studies being done now on the material they brought that weren’t possible then. The same will happen with Mars samples — there will be analyses and work for decades to come.