On April 11 this year, the Israeli spacecraft Beresheet was about to land on the moon when it lost contact with Earth and crashed into the moon. Its precious cargo included a DVD-sized archive of 30 million pages of information… and thousands of tardigrades. Tardigrades, also known as “water bears,” are microscopic organisms that can survive under harsh conditions like radiation, extreme temperatures, and dehydration.
So should we be worried?
Without water, the moon is unlikely to support extraterrestrial life. The tardigrades spilled on the moon were dehydrated, meaning that for them to come back from dormancy, they need water - something they can’t get on the moon. (Another source of contamination: Apollo astronauts left 96 bags of human feces on the moon. It’s debated whether the microbes in there are alive or dead.
But for planets like Mars that has potential for supporting life, contamination is more worrisome. A tardigrade spill on Mars could endanger any possible life. This is why space missions to Mars and other moons, such as Europa, undergo sterilization precautions to reduce the chance of microbes from Earth hitching a ride to another celestial body and vice versa.
Yet, can we actually safeguard against interplanetary contamination? Meteorites have bombarded planets for billions of years potentially transferring microbes from one planet to another. Some scientists think that interplanetary contamination has already happened. But it doesn’t hurt to be careful just in case.