If you were on Mars, for example, you would not want to have to contact Earth every single time you wanted to load a web page. And so you would contact Earth the first time to load it. And then it would be saved locally.

Don’t ISPs already do something like this to save on bandwidth on their side? Just saving local copies of commonly accessed files.

At least I remember hearing about that a decade ago, I wonder if that can still happen now that there’s basically https everywhere.

But at any rate, I believe there are at least well established methods for that.