Tardigrades, known to many as water bears or moss piglets, may be the cutest organisms you need a microscope to see. They're also remarkably tough: The miniscule creatures are capable of producing glass shields in their cells to protect themselves in extreme conditions, and they can survive almost anywhere, including space. Now, as BBC News reports, their resilience is being put to the test. Last April, an Israeli spacecraft crashed and dumped thousands of tardigrades on the Moon, and mission officials say their chance of survival is "extremely high."

The spacecraft that crash-landed on the moon last spring had been carrying a "backup of planet Earth." The mission was organized by the Arch Mission Foundation, a nonprofit that aims to amass libraries of human knowledge and history and store them in various spots around the solar system for safekeeping. This particular collection contained human DNA samples, a CD-ROM-like disc inscribed with 30 million pages of information, and dehydrated tardigrades.

The lunar library hitched a ride aboard Israel Aerospace Industries' Beresheet spacecraft in what was to be the first-ever private Moon landing. The endeavor failed at the last minute when the lander's main engine malfunctioned as it approached the Moon's surface, resulting in a collision. The Beresheet spacecraft may not have survived the journey, but according to Arch Mission Foundation CEO Nova Spivack, its thousands of tardigrades passengers likely did.

When tardigrades are dehydrated, they're virtually indestructible. In the face of danger, they enter this near-death state on their own and manage without food, water, or even air until conditions improve. They can live this way for decades without an issue, and when they're rehydrated, they instantly resume life as normal.

Spivack's prediction that the tardigrades are doing fine on the Moon is more than just a hunch: The creatures have been brought to space before and survived. This case, however, isn't a controlled experiment, and introducing a new species to the surface of the Moon could have unforeseen consequences. Humans have left objects on the Moon before—like golf balls, art, and even feces—but never such complex living organisms.

If the lunar library remained intact through the crash, it may be possible for future missions to retrieve it and conduct tests on the tardigrades once they are brought back to Earth. Until then, there's a strong likelihood that Earth is no longer the only celestial body in our solar system that's supporting life.

[h/t BBC News]