"garbage"

The moon has no people and no other living creatures, but scientists have found a lot of garbage on the surface of the moon, which is very strange, since the moon has no people, why would there be so much garbage?

So far, we have not found any trace of life on Mars. No one knows whether there is life on Mars. However, when we are exploring Mars, sometimes we will see some interesting scenes, even some garbage. It is strange that there is no one on Mars. Why is there garbage? Where does this rubbish come from?