A few rule for the cleanroom where NASA’s new InSight Mars lander waits for launch. One, if you must sneeze, sneeze away from the spacecraft. Two, if you drop anything, let one of NASA’s escorts pick it up for you. Three, do not under any circumstances cross the black-and-yellow-striped tape and touch the spacecraft.

Oh also—an engineer tells a dozen media in a conference room at Vandenberg Air Force Base—do not lick the spacecraft. There’s always that one rebel, I suppose.

The reasons to behave ourselves are many, and they are serious. For one, InSight costs nearly a billion dollars, and although it’s engineered to survive the punishing journey to Mars, it’s not engineered to be licked. And two, this conference room is loaded with planetary protection specialists, whose oh-no-big-deal job is to make sure Earthling microbes don’t end up colonizing Mars. And not just for the solar system’s sake—NASA is obligated by international treaty to keep other planets clean. In just a month, it’ll fire InSight to the Red Planet, where the lander will drill to unravel the geological mysteries of our solar system’s rocky bodies.