Humans Could Kill Life On Mars, If It Doesn’t Kill Us First

A human visitor to the Red Planet could bring along a devastating microbe on his spacesuit, or bring one back to Earth when he returns.

Humans may some day visit Mars, but if (when?) we do, we run the risk of bringing a bacterium or virus that could wipe out all life on the Red Planet, is reporting. What’s worse, when we return home from Mars, we may bring a deadly pathogen home with us that could wipe out all life on Earth.

The microbiology community has known for a century or so that organisms’ immune systems don’t always respond very well to “foreign” microbes to which they’ve never had exposure. That’s why when Europeans first visited the Western Hemisphere, they brought with them smallpox, a devastating disease that had been in their own populations for millennia, but which were new to the Native American tribes. By some accounts, smallpox killed up to 1.5 million Native Americans.

And in the case of a literal alien organism, the effects could be much, much worse.

A spacecraft is, in some ways, a vector of human and other Earth-bound diseases. That’s why NASA sent the Cassini probe to a fiery death in Saturn’s atmosphere after it had completed its mission; scientists were concerned that the craft might have brought along some Earthly microbes that could infect whatever rock it landed on. Instead, they sent it to its certain death, according to .

HiRISE 4K: A Dark Area in a Crater Floor

Similar regions observed by the THEMIS instrument onboard Mars Odyssey have proven interesting, revealing dunes and bedrock.https://t.co/ZprweSZaMu

NASA/JPL/University of Arizona#Mars#sciencepic.twitter.com/n3IbNUDISo

— HiRISE (NASA) (@HiRISE) December 17, 2018

The problem is magnified exponentially when it comes to Mars. Already scientists take great care to sanitize and disinfect any craft that winds up there, lest it introduce a fatal disease into the Martian ecosystem (if there is or ever was one, that is). Pardis Sabeti, professor of immunology and infectious diseases at Harvard University, says that, even unintentionally, an Earth microbe could devastate Mars.

That’s why we’ve been sending robots up there: besides being cheaper, they’re also cleaner. Indeed, Sabeti notes that a Mars-bound spacecraft is subjected to high heat for days to kill off all microbes, something that can’t be done with humans. And when we do figure out a way to send humans up there, each one will be bringing along with them literally trillions of bacteria and viruses.

Even worse, an astronaut or spacecraft returning from Mars could bring with it a potentially-lethal Martian microbe, says Sabeti.

That’s why any returning Martian spacecraft, or human visitor, will have to spend days in a containment lab once they get back. But if we do manage to bring back a sample of a living Martian organism, it will all be worth it, says said Casey Dreier, chief advocate and senior pace policy adviser at The Planetary Society.

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