How a popular UT geology professor ended up as a leader on NASA's Mars 2020 mission


Dr. Linda Kah is an incredibly adventurous soul. The University of Tennessee geology professor and paleontologist has traveled to the most remote places searching for the origins of life on our planet. In a Science Forum presentation several months ago, Kah held a local audience spellbound as she described working in the Canadian Arctic, hunting for bacterial fossils on the tundra with her small team.

"Our only visitor was a baby Arctic fox who on a series of incredibly wet, nasty, windy cold days would crawl under the rain fly of our tent and curl up to sleep next to us," Kah said at a presentation back in February.

Her work will go someplace she ever expected to go: Mars.

"No way did I ever think I would end up working on Mars," Kah laughed in a video interview with Knox News. "In fact the only part of science that has never been really interesting to me has been space."

Kah is a lead co-investigator on NASA’s Mars 2020 mission, which is set to launch this week.

Mars 2020 is the mission to send up the rover Perseverance to test key technologies for an eventual crewed mission. It's designed to find evidence of ancient microbial life.

Kah has decades of experience doing similar work on Earth, examining life too small to leave traditional fossil remains. 

"When you're looking at rocks that are a billion years old there's pond scum, there are microbes but they don't have hard parts," she explained. "How does that information get trapped in a rock, and translated to where we can see things, and say something about them?

"When you look at geology, it's the same skill set. I'm just doing it on now on a different planet."

All about Perseverance

For several years, scientists across the world have been building the next generation of Martian rover while planning its mission to the Red Planet. Perseverance is the most advanced, largest and heaviest robotic vehicle NASA has built to date. It’s roughly the size of a car and carries many high-tech instruments, including a laser capable of vaporizing rock for chemical analysis and a ground-penetrating radar system capable of identifying underground water or ice. The rover will also stress-test spacesuit material and demonstrate a carbon dioxide to oxygen converter.

A scaled-up converter could be used to make breathable air and rocket fuel for a crewed mission.

Unlike prior rover missions like Curiosity, Perseverance carries a passenger - a helicopter drone named Ingenuity. The drone will be the first human attempt at powered flight in the thin Martian atmosphere.

The rover’s target is the now-desolate Jezero crater. Located on the western edge of the Isidis Planitia, a giant dusty plain, the Jezero may have held a body of water the size of Lake Tahoe 3 to 4 billion years ago. Scientists hope to find evidence of past water and nutrients that may have supported life here. 

There is good reason to think they might find such evidence. Using telescope and orbital imagery, scientists identified two dry river channels that appeared to flow into the crater. Clay deposits resembling river deltas fan out into the Jezero.

Carbonate minerals like limestone have been detected in these deltas. These minerals are used by living things of all sizes to build hard parts like shells. Carbonate crystals can also trap evidence of ancient bacteria. It's something that happens on Earth right now in hot springs like the Grand Prismatic Spring in Yellowstone National Park.

"It's a really good way of locking organic matter in a crystal, therefore protecting it," explained Kah. "That's what we want to look at if we want to find evidence for life."

Mars 2020's mission for future scientists

If all goes according to plan, Perseverance will land on the remains of the western delta, survey the site and take core samples in and around the delta. NASA hopes the process will take roughly one Mars year, or 687 days. Once the samples are collected, NASA intends to send another mission to recover the core samples and return them to Earth.

But that process will take a while. The samples won't be returned until roughly 2031.

"By the time the full fruits of this mission get back to Earth, it should be 2031, and I'm scheduled to retire in 2032," she said, "so this is really work for future scientists and not me."

The mission almost did not happen due to fallout from the COVID-19 shutdowns earlier this year. The team at NASA’s Jet Propulsion Laboratory finished the rover with not a moment to spare.

"I remember being there to wave it off," said Katie Stack Morgan, the deputy project scientist for Mars 2020. "And in a couple of weeks, we were now all at home."

"I think if COVID had hit even or month or two beforehand, we would have been in a different situation and might have been talking about slipping the launch," she continued.

With Perseverance built there were very few scientists who had to be present to make the final launch preparations. The other members of the scientific team would be working remotely from all over the world anyway. There are also very limited windows for a craft from Earth to make a transit to Mars.

"There are whole regions of time where we cannot even consider launching a rocket to Mars," said Kah. She explained that to get to Mars, scientists basically have to lead a shot far, far in advance so that the rocket will be where Mars will be positioned in up to a year's time.

"When you have a window you do everything in your power to make it," she continued.

The Mars 2020 Perseverance rover mission's disk-shaped cruise stage sits atop the bell-shaped back shell, which contains the powered descent stage and Perseverance rover. Below is the brass-colored heat shield that is about to be attached to the back shell. The image was taken on May 28, 2020, at Kennedy Space Center in Florida. The next time the back shell and cruise stage will separate will be about 6 miles (9 kilometers) above Mars’ Jezero Crater on Feb. 18, 2021.

Rover missions to Mars have been happening more or less continuously since Sojourner landed on the planet 23 years ago. Each new rover builds on the work of previous missions and serves as an avenue for new experiments.

"This is a decade's worth of work by thousands of people to get us here," said Jim Watzkin, director of the Mars Exploration Program. "It's had a half-dozen missions proceeding it as we have learned how to land and survive and work on the surface of Mars."

A bigger goal

Watzkin emphasized that the long-term purpose of Mars 2020, from collecting samples to their eventual return in 2031, was a test run for an eventual crewed mission next decade.

"We're oftentimes looked at as an essential precursor of human exploration," he said.

Every branch of science is to some extent an inter-generational project. Each discovery, each project, each study is in reference to and dialog with earlier work. That’s especially true with interplanetary exploration. Scientists and engineers start projects that they may never live to see finished, hoping the next generation will pick up where they left off.

"There are times when you have to step back from an idea," said Morgan. "Maybe I'm not going to be the one to follow up on it but that's OK."

"Any Mars exploration is a good, positive advance to our understanding of the solar system, regardless of which country is doing it or who has their name on it." she continued.

That intergenerational, optimistic vision is part of Kah's work as well and not just in terms of returning Martian samples to Earth for future scientists.

"I just love the fact that, you know, whatever role I play on this mission I can make that play larger in my community by giving these opportunities to students," said Kah.

Source: Knoxville News Sentinel, by Vincent Gabrielle

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Published July 31, 2020