Tardigrades, also known as water bears, are probably the toughest creatures on Earth. The microscopic organisms can survive for decades completely frozen with no moisture and can survive high heat and pressure that would basically make any other living thing explode. And now, reports Daniel Oberhaus at Wired, it’s possible that a colony of them are living on the moon.
The story of the tiny lunar bears began last April, when Israel Aerospace Industries' Beresheet probe and lunar lander—the first object sent to moon by a private company—crashed into the moon’s Sea of Serenity, a lunar plain created by an ancient volcanic eruption. Aboard the lander was a DVD-sized package, called a lunar library, that belonged to the Arch Mission Foundation, a nonprofit focused on creating “a backup of planet Earth.” While the lander was destroyed, Wired’s Oberhaus reports a package aboard the craft is believe to have survived. Within it, were thousands of little tardigrades, stuck to the payload via special tape.
After consulting with technical advisors and viewing imagery of the crash site taken by NASA’s Lunar Reconnaissance Orbiter, it appears the object was probably ejected from Beresheet and is sitting on its own, away from the crash site. American entrepreneur Nova Spivack, founder of Arch Mission, says the heat of the crash was not enough to melt the nickel disks of the library, which are encased in several layers to block cosmic radiation. “Ironically, our payload may be the only surviving thing from that mission,” Spivack tells Oberhaus.
That payload contains much more than water bears. The purpose of the Arch Mission Foundation is to send repositories of human knowledge into strategic locations in space. If humans survive into the future, the libraries can serve as time capsules of days gone by. If humans don’t survive, they will stand as monuments to our species and will give any intelligent life that finds them access to our history, science and literature.
Surprisingly, a large amount of the human experience is crammed into the little library. The gadget is made up of 25 nickel disks. The first four include analog, nano-scale etchings of 60,000 pages worth of information readable using various microscopes. Those documents reveal how to access the digital information on the other 21 discs. Digitally embedded on those disks is all of the English Wikipedia, thousands of classic books, a linguistic key to 5,000 languages, and an Israeli time capsule that includes descriptions of its culture and history among other things.
Oberhaus reports that human DNA samples are also included in the library, sandwiched in layers of epoxy resin between the 40 micron nickel disks with hair and blood from 24 humans embedded as well. There’s also bits of holy sites, including a sample from the Bodhi tree in India, in those layers. For good measure, extra tardigrades were stuck to tape that that was attached to the library.
The question now is, are those tardigrades able to survive on the lunar surface? It’s definitely possible. Brian Resnick at Vox reports that on Earth, tardigrades are able to enter a special state called cryptobiosis, which makes them almost indestructible. In this state they pull in their legs and expel almost all the moisture from their bodies. When they enter this type of hibernation they’re called tuns, and they were in that state when sent to the moon.
But there’s more going on than just pulling in their legs. For starters, their metabolism decreases by 99.9 percent. Then they produce glycerol, which is essentially antifreeze, and also secrete a simple sugar that turns into the equivalent of a suit of armor. It’s enough to survive in space, at least for a little while. In 2007, a European Space Agency satellite exposed tardigrades to cosmic radiation in open space for ten days. When they were returned to Earth and rehydrated, some of the microscopic water bears woke up.
Even if the Beresheet crash was more catastrophic than believed, tardigrade expert Lukasz Kaczmarek, at the Adam Mickiewicz University in Poznań, Poland, tells Ian Sample at The Guardian the animals likely survived. “Tardigrades can survive pressures that are comparable to those created when asteroids strike Earth, so a small crash like this is nothing to them,” he says.
But that does not mean future astronauts will find colonies of the little guys spreading across the moon. As tuns, the animals may live on for years. But they would quickly die if they came out of that special hibernation state. “They cannot colonize the moon because there is no atmosphere and no liquid water,” Kaczmarek says. “But it could be possible to bring them back to Earth and then add the water. They should resurrect.”
Resnick reports that if astronauts ever investigate the Beresheet crash site and find the bear-filled library, it could help researchers answers some questions about life itself. In particular, if the little tardigrades can survive for extended periods on the moon, it might mean life can propagate throughout the universe, spreading via hardy microbes hitching a ride on comets and asteroids.