We’re pretty close to destroying the Earth, but good news! We might soon have the chance to transform another planet into “an immense pile of filth” — NASA announced today that it has discovered evidence of liquid water, the kind that could potentially support human life, on Mars.

Actually, they’re not one hundred percent sure it’s actually water just yet. All they have right now are some photos captured by the Mars Reconnaissance Orbiter that suggest there’s something there that looks and acts like water — streaks that “appear to flow down steep slopes during warm seasons, and then fade in cooler seasons.”

Great! So, we’ll just send the rovers over to confirm, right? Ha! Funny thing about that, Rich Zurek, chief scientist for NASA Mars program, says: actually, we can’t, for reasons including but not limited to the fact that scientists are afraid Curiosity and Opportunity maaaaybe carrying microbes from our dirty, disgusting planet.

As Zurek put it in a Reddit AMA earlier today, “These regions are considered special regions where we have to take extra precautions to prevent contamination by earth life. Our current rovers have not been sterilized to the degree needed to go to an area where liquid water may be present.”

But don’t worry — NASA’s got samples of any microbes they may have already contaminated Mars with “so we can compare with any future discoveries,” Zurek said.

At least they know those microbes they’ve got samples of won’t do damage! Right? ...Right?

Actually, deputy project scientist Leslie Tamppari says “We don’t know what Earth life could do to any potential life on other worlds. That’s why we try to clean our spacecraft very carefully.”

Listen Leslie, I don’t want to be the one to tell you this, so I’ll let Master Yoda do it: