Sometime within the next five years or so, NASA plans on sending humans back to the Moon. Looking to the future, NASA is laying the groundwork for crewed trips to Mars as well, and all of this exciting space exploration has inevitably led many to question just how long before humans set up shop on another world.

Michel Mayor, a Nobel Price winning scientist in the field of physics, isn’t too keen on talk of humans leaving Earth for greener pastures. In fact, in a recent interview with AFP, Mayor says he doesn’t see any way that humans will ever colonize Earth-like exoplanets, and that we should be spending our considerable resources keeping Earth healthy rather than dreaming of leaving it.

Mayor makes his case by noting that the distance between our planet and neighboring solar systems is absolutely massive. He’s right, of course, and even those exoplanets that appear potentially habitable from our vantage point are still far too distant for us to be sure.

Even if we knew for certain that a planet was habitable and that humans could exist freely and safely on its surface, we have no real way of getting there. Distance, time, and safety are all prohibitive factors, and uprooting our civilization in favor of somewhere new isn’t even a remote possibility.

“These planets are much, much too far away. Even in the very optimistic case of a livable planet that is not too far, say a few dozen light-years, which is not a lot, it’s in the neighborhood, the time to go there is considerable,” Mayor told AFP. “We are talking about hundreds of millions of days using the means we have available today. We must take care of our planet, it is very beautiful and still absolutely liveable.”

Mayor takes particular issue with the notion that when humans fully ruin Earth, we can simply move on, accurately calling it “completely crazy.”

Humanity doesn’t have a lifeboat right now, and it’s possible we never will. Technology may allow us to explore other worlds and eventually even other solar systems, but it’s incredibly unlikely that mankind will ever just pack up and leave. With that in mind, it’s probably best we keep our only planet in working order.