Pack in what you pack out apparently does not apply to astronauts. While it may seem irresponsible of humanity to leave our junk on extraterrestrial landscapes, it is rather costly to bring it all back. Every pound of stuff we bring back requires that much more fuel. We need more fuel to carry that fuel.
That’s why it is especially easy to leave behind our feces, urine and vomit. Why make room for these stowaways?
As NASA lands its new rover, Perseverance, on Mars today, I still have a childish fascination with the fact that we are actually exploring other planets. How cool is this?!