NASA has updated its Planetary Protection Policies to reduce the spread of Earth germs in the vastness of space. Though space is seemingly endless compared to the Earth, a mere speck of dust in comparison to the size of the universe, NASA wants to ensure that humans aren’t dirtying up the place with our germs as people travel to the moon and beyond. In any case, no matter how small we — and especially our germs — are compared to the cosmos, dirt is dirt, and the US’s National Aeronautics and Space Administration wants to keep outer space contamination to a minimum. To prevent humans from ever getting into a spat with extraterrestrial street cleaners that could very well possibly be out there, NASA has updated the Planetary Protection Policies for Robotic and Human Missions to the moon, Mars and eventually beyond. The first modification “addresses the control of forward terrestrial biological contamination associated with all NASA and NASA-affiliated missions intended to land, orbit, or otherwise encounter the Moon.” To simplify, the organization requires that no biological matter is left on or around our moon, not even microscopic beings. The second addition specifies that when people travel to Mars in the future, neither forward nor backward contamination should occur, meaning that humans should not contaminate Mars with biological materials, and when they come back, they likewise must not contaminate Earth with Martian biological materials. Associate Administrator of NASA’s Science Mission Directorate Thomas Zurbuchen explained that such precautions should be taken to protect these sites, as they “have immense scientific value in shaping our understanding of the history of our planet, the Moon and the solar system.” Both these changes were officially published Thursday.