Earth must make sure rocks on Mars are free of alien germs: NPR


NASA’s Perseverance rover took this “selfie” next to a rock where it drilled for samples. NASA wants to bring samples collected by this rover back to Earth.

NASA/JPL-Caltech/MSSS


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NASA’s Perseverance rover took this “selfie” next to a rock where it drilled for samples. NASA wants to bring samples collected by this rover back to Earth.

NASA/JPL-Caltech/MSSS

NASA is planning its first-ever mission to bring dirt and rocks from Mars back to Earth – but before that momentous event happens, the space agency must figure out exactly how to protect our home planet from any alien microbes that might hitchhike .

This week, the agency is holding public meetings and seeking feedback on its plan to land a spacecraft carrying Mars specimens at a US Air Force testing range in Utah in the early 2030s.

“This may be the most important environmental assessment humans have ever made,” says Peter Doran, a geologist at Louisiana State University who studies life in extreme environments.

“I think there’s a very low probability that there’s anything living on the surface of Mars,” says Doran, who also sits on an international committee dedicated to planetary protection. “But there is a possibility.”

Having a rock sample from Mars here on Earth would allow scientists to perform exhaustive laboratory tests to seek evidence of whether this cold, harsh, rocky world was once habitable and possibly even inhabited.

For scientists, this is a long-held dream

Such a mission has been talked about for decades, and it will cost billions of dollars to accomplish. Still, Doran says no one has thought through exactly how to handle the Martian specimens. Questions like how to contain potential microbes? Or what specific features are needed for the secure lab (or labs) that will house the stones?

“Until recently, we didn’t focus much on the details of the sample return setup and all that,” he explains, “because we didn’t think it was going to happen.”

Now, however, the effort appears to be on a fast track, with NASA officials collaborating with the European Space Agency and planning to launch a set of recovery spacecraft as soon as 2027 and 2028. To prepare, the Perseverance rover from NASA, which landed on Mars last year, drilled cylindrical samples of rock and sealed them inside metal tubes.

“We now have eight samples on board the rover,” says Jim Bell, a planetary scientist at Arizona State University who is part of the Perseverance rover team.

He explains that the rover explored an ancient crater on Mars that appears to have once had water. Occasionally, the rover drills a cylindrical core of rock the size of a dry-erase marker. The core is then hermetically sealed in one of the rover’s 42 metal sample tubes.

Bell says a long-standing joke among planetary scientists is that “the return of samples from Mars has always been delayed by 10 years.” But hey, it really seems like 10 years from now, he says.

“I’m optimistic, aren’t we? We cache them and prepare them for fetching,” Bell says. “And so it’s further than the planetary science community has ever been before.”

Critics say Martian rocks carry risks

NASA officials hatch a plan to collect the samples safely: A spacecraft would land on Mars and launch a container filled with previously collected rock samples into orbit around the planet. Once in orbit, this container could be swallowed up by another container – like a big fish eating a small fish – to keep everything inside that touched Mars.


This conceptual illustration shows a container carrying rock samples exploding on the surface of Mars.

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This conceptual illustration shows a container carrying rock samples exploding on the surface of Mars.

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It would then be sealed, and the seal would be heat-sterilized, says Brian Clement, a planetary protection expert at NASA’s Jet Propulsion Laboratory who works on the mission.

“We’re applying very high heat. It’s going to exceed 900 degrees Fahrenheit,” he says. “We want to be able to separate out any biomolecules that might have activity of concern.”

It’s technically difficult, however, because scientists also want to keep the rock samples cold, like they were on Mars. “I liken it to welding your lunch box to metal while trying to keep your lunch chilled inside,” says Clement.

The sanitized container would then go into another container, which would also be sealed and placed in the Earth Entry Vehicle, which would eventually land in the Utah desert, without a parachute.

“We like to call it a 90-mile-per-hour fastball, where the landing site is the glove,” says Clement. “That 90 mph landing, just like with a baseball, is well within the capabilities of Earth’s entry system.”

However, some observers find this proposal disturbing.

“We’re just going to take it back and bring it back to the Utah desert, much like the Genesis solar sample return mission, which of course broke open on impact” says Barry DiGregorio, a science writer with a group called the International Committee Against Mars Sample Returns, which has long opposed plans to bring Martian rocks directly to Earth.

“You can imagine what would happen if you had pathogenic organisms from another planet and this kind of thing happened,” says DiGregorio.

But Clement says that several panels of scientific experts have weighed in on the risk of returning samples from Mars over the years and that “these panels have all agreed that the potential danger is very, very low.”

Even so, he says, NASA takes a conservative approach. “Anything that has come into direct contact with Mars will be contained or sterilized before being sent back,” Clément explains.

And Bell says he’s not worried about the possibility that Martian germs mixed in with the rocks could escape into the environment and cause problems or illnesses, “despite the fact that many sci-fi fans s ‘probably worry about it’.

Any life on Mars would be ill-suited to survive on Earth, Bell says, because it would have evolved in a separate biosphere, or environment that supports life. “We’re talking about a completely different ecosystem, a completely different potential biosphere,” he says. “And, of course, we don’t know at all if there is or was a biosphere on Mars.”

According to him, the main danger of a rupture or a leak would be to contaminate the precious Martian samples with terrestrial material. That’s why the samples will likely need to be opened in high-tech facilities capable of replicating the environment and atmosphere of Mars, Bell says.

Audience reaction to a special Mars delivery

While Mars’ surface is currently dry, very cold, and blasted with harsh ultraviolet rays, LSU’s Doran says it’s still possible for microbes to survive in shielded cavities and holes or under dust.

“The possibility is not zero,” Doran says, though he thinks it’s “highly unlikely.”

“We definitely need to take this position of protecting Earth, at least in the early missions, until we know what’s out there,” he says.

One of the few efforts to determine what the public thinks of bringing home Martian rocks was done in the 1990s. This study found that “public perception of the biological hazards associated with a return mission of samples on Mars is not considered a significant risk compared to other technological and environmental risks and hazards, such as nuclear technologies, food hazards and ozone layer depletion.”

But public perceptions might be different now, in part because of the coronavirus pandemic, says Margaret Race, one of the researchers involved in this 1990s study, who worked on planetary protection with the SETI Institute.

“What we’re talking about is bringing it to Utah in a big desert and then you pick it up and take it somewhere else, a lab,” Race says, pointing out that people are going to want to know where this is. laboratory. will be and exactly what protections will be in place.

“I can expect there to be a lot of questions,” she says.

Even with many details to iron out, the prospect of a Martian rock being brought to Earth is nothing short of exciting to scientists like ASU’s Bell, who have been studying Mars for years.

“I just want to see this stuff with my own eyes,” Bell says. “We’ve been looking at this world through robotic eyes for so long, and I want to see this famous red dust and I want to see inside some of these rocks and little grains that may have formed in a watery environment 3 or 4 billion years ago.”

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