To find signs of life on Mars, scientists visit the harshest places on Earth
For years, scientists have picked apart data transmitted from Mars probes to find signs of life on the red planet. But since the Martian landscape is too harsh to support most kinds of life, some scientists in St. Louis travel to remote places to study life that thrives in extreme environments.
If life exists on Mars, scientists think it’s likely in the form of tiny organisms that live underground, because the surface receives large amounts of radiation. Mars missions have also revealed that the planet has large concentrations of a toxic, salty substance called perchlorate. Life on Mars would likely be able to tolerate dry, salty environments, so researchers have looked for similar places on Earth.
The locations include the Qaidam Basin in Tibet, the Atacama Desert in Chile and the hot springs in the Arctic. Pablo Sobron, a St. Louis-based researcher who works at the SETI Institute — the Search for Extraterrestrial Intelligence — has gone to all three places to collect samples from the environment.
“We’re trying to catalog extreme life on Earth so we have a better idea of what to look for on Mars,” Sobron said. “The more we go to the field, the more we learn about life that happens there and how it’s affected by the environment, the more ready we’re ready to find life elsewhere.”
Sobron conducts some of his research in collaboration with Alian Wang, a planetary scientist at Washington University. In a white-walled, windowless laboratory inside Wash U’s Rudolph Hall, they use lasers, sensors and other instruments to analyze samples collected from the field and synthetic samples made in the laboratory.
On Mars, rovers use lasers to break down materials in the environment to study what elements they’re made of. In the laboratory, Sobron and Wang demonstrate a laser hitting a pellet made from a sample collected from a hot spring in the Canadian Arctic.
“On Mars, you cannot touch [the samples], you cannot smell it, you cannot look at it,” Sobron said. “The more you practice in the lab, the more you build your expertise in the field and you can compare the stuff on Mars.”
The researchers also place samples into a complex machine that Wang calls the “PEACH,” which stands for Planetary Environment Analysis Chamber. It's able to simulate conditions that exist on other planets and moons. She’s configured the PEACH to recreate the electronic storms that occur during a Martian dust storm to understand the role that storms play the formation of perchlorate salts on Mars.
In 2020, NASA, the European Space Agency and the China National Space Administration will launch three missions to advance exploration on Mars. Wang and Sobron’s research will support the ESA’s ExoMars Mission that’s focused on finding signs of life on Mars.
“Every time we send a rover there, there are new discoveries and it raises more questions,” Sobron said.
“It’s never boring,” Wang added. “It’s so exciting to see new things.”
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