There's only so much time left to look for life on Mars before life comes from Earth

STANFORD, Calif. – NASA has been searching for life on Mars for more than 40 years, but the search could get much more complicated when earthly life arrives en masse, perhaps in the next decade.

"There is" Princeton astronomer Chris Chyba said at the Breakthrough Discuss conference last week, held at Stanford University.

The problem has the potential to pit scientists like Chyba against rocketeers such as billionaire SpaceX Elon Musk, who wants to start sending settlers. to Mars in the mid-2020s. When humans and all the supplies they need start arriving by the ton, there is a risk that their biological signature could crush any trace of ancient or modern life on the Red Planet.

In the last week, the CEO of Boeing Dennis The president of Muilenburg and SpaceX, Gwynne Shotwell, said they have hopes that humans will reach Mars in a decade. And Shotwell made it clear that once that happens, the planet will probably never be the same. "It's a superior fixative planet," he said at last week's TED conference in Vancouver, BC

Jeff Greason, a longtime space entrepreneur and chairman of the Tau Zero Foundation, presented the topic in Breakthrough Discuss in the form of an application: "If all you want to do with the solar system is look at it, the rest of us would like to borrow it for a while." … There are things to do with these bodies in addition to science. "

Chris McKay, a planetary scientist at NASA's Ames Research Center, took a different turn to Greason's request for the benefit of his fellow scientists. "How long do scientists try to keep pollutants out of our planet?" He asked, half jokingly.

Carol Stoker, a colleague of McKay at NASA Ames, responded that there would have to be "a finite" number of investigations : a minimum of one ", using the advanced life detection tools that are being developed for interplanetary missions. Such research should sample "some well-chosen sites" where Martian life can lurk beneath the surface of the planet's radiation.

"If it's not life, then we're pretty confident that we really do not have life on Mars, and there's no conflict," Stoker said. "If it's there, then we need to understand it better."

Astrobiologists would like to learn about the biochemistry of Martian life, and whether it is so different from earthly life that it represents a truly alien genesis rather than a case of exchange of planetary crossover microbes. They would also want to see how it interacts with the organisms on Earth, and if such interactions have negative effects.

Discovering what one life form does to the other would be crucial for planetary protection, not only for Martian organisms, but also for humans and other Earth-based life as well. No one wants to see the kind of scenario depicted in movies that range from "The Andromeda Strain" to "Life."

On one side of the debate, some would say that the risk of damaging Martian life is so great that the human habitation should never be allowed on the red planet. They can point to the 51-year-old Outer Space Treaty, which obliges the United States and other signatories to avoid the "noxious contamination" of other celestial bodies.

On the other hand, the supporters of the settlement of Mars say that the niches where Martian life could most likely exist underground and so isolated that human activities would represent a small risk. "You could terraform Mars, and the microbes on Mars would survive," said Robert Zubrin, founder and president of the nonprofit Mars Society.

Some argue that terrestrial life has already reached Mars, through meteorites and NASA landers and rovers. There is even a hypothesis that states that earthly life had its origin in the Martian microbes transported by space traveling the other way. Therefore, it is too late to worry about another biological invasion, they say.

Chyba of Princeton advocates a middle ground, which he calls the Smokey the Bear argument: "Until we know more, let's be careful"

. "Once we start sending humans to Mars, we should not just admit that's okay, let's ruin the biosphere now, "he told GeekWire. "First of all, there must be steps that we can take to minimize our impact, and that will have to do with where we landed and also with technology, we should consider that we should try to minimize the number of microbes that we are expelling from our structures and that they are escaping our space suits. "

If scientists rule out the existence of the indigenous Martians "Life is good, then safeguards do not need to be so tight," Chyba said.

The good news for astrobiologists is that the clock may not be working as fast as Shotwell and Muilenburg make it sound. The timelines for Mars missions are notorious for slipping to the right, as evidenced by the return missions of Mars samples that were supposed to have flown more than a decade ago. The first trip with crew to the Red Planet may well be delayed until the 2030s, which is more in line with the program established by NASA for the exploration of Mars.

Who knows? By the time the first astronauts on Mars enter the BFR SpaceX rocket, NASA's Orion deep space capsule or some other spacecraft, there will have been multiple robotic missions to solve the question of life on Mars once and for all, and enough time for space officials, scientists and settlers to agree on the rules of the road.

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