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What a decade of Curiosity has taught us about life on Mars

A self-portrait of NASA's Curiosity Mars rover on Vera Rubin Ridge.
AP
A self-portrait of NASA's Curiosity Mars rover on Vera Rubin Ridge.

Ten years ago, engineers at NASA's Jet Propulsion Lab celebrated the successful landing of its fourth robot on Mars, The Curiosity rover.

Now old enough to enter the fifth grade, the Curiosity rover was set on its mission in 2012 to determine whether the red planet could have ever supported life.

The robot is about the size of a car, and is decked out with scientific instruments used to study the planet's climate and geology. So, how did the mission go? And what can the Curiosity rover teach us about the past, and potential future of space exploration?

Engineers work on a model of the Mars rover Curiosity at the Spacecraft Assembly Facility at NASA's Jet Propulsion Laboratory in 2012.
Damian Dovarganes / AP
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AP
Engineers work on a model of the Mars rover Curiosity at the Spacecraft Assembly Facility at NASA's Jet Propulsion Laboratory in 2012.

Clear signs of habitability

Dr. Ashwin Vasavada is the head scientist of the Curiosity team, and says that the mission was a huge success.

"[We learned] it was not only habitable at one moment in time in Mars' history, but probably habitable for millions, or tens of millions, of years," he said.

While the rover was able to detect minerals and water that could have supported life, that doesn't necessarily mean that Mars itself harbored life. Vasavada said that their initial goal was to find out if life was simply even possible there.

"We've explored Mars enough to know that there are no dinosaur footprints, no big life forms around today," he said. "So if life ever did take hold, it probably never got beyond kind of a microbial stage."

A sharp change

So, why did Mars become uninhabitable?

Vasavada thinks it's likely a combination of events.

"You can see evidence that rivers once coursed along the surface, that maybe even an ocean existed at one point. So early Mars, we're talking three or four billion years ago, was a much more Earth-like place than Mars is today," he said.

This image provided by NASA, assembled from a series of January 2018 photos made by the Mars Curiosity rover, shows an uphill view of Mount Sharp, which Curiosity had been climbing.
/ AP
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AP
This image provided by NASA, assembled from a series of January 2018 photos made by the Mars Curiosity rover, shows an uphill view of Mount Sharp, which Curiosity had been climbing.

And it seems that the size of the planet may have been the main factor in ending the development of life.

"Ultimately, it's a smaller planet than Earth, [so] that allowed it to cool faster. Once it cooled faster, it lost its ability to generate a magnetic field," he said. "Once the magnetic field stopped, the atmosphere was stripped away by radiation in space. And that led to its inability to, at that point, stay warm and have liquid water."

From that point on, the planet became the cold and inhospitable desert that it is known as today.

A unique landing point

Even the spot that the Curiosity rover initially descended on 10 years ago was able to provide new insights for the team working to understand Mars.

The rover landed in an area called the Gale Crater. Known as an impact crater, the cavity was formed when a large space rock hit the surface of the planet. Later on, it was filled with sediment deposited in lakes, and formed layers of mud that built up over time into the sides of a mountain.

"What this meant is that we could land there, and see if that sediment really was deposited within liquid water environments, like lakes and streams," Vasavada said. "We could read the early history of Mars by driving up these rock layers, and determining whether any of those periods of Mars' time had these habitable conditions."

After 10 years, the success of the mission still surprises the scientist.

"We've now driven up over 2,000 vertical feet on the mountain, and for the most part, every layer we've looked at formed in a wet environment and had conditions that would have been favorable to life."

Copyright 2022 NPR. To see more, visit https://www.npr.org.

Ailsa Chang is an award-winning journalist who hosts All Things Considered along with Ari Shapiro, Audie Cornish, and Mary Louise Kelly. She landed in public radio after practicing law for a few years.
Kai McNamee