misscrabtree456: Whoa, nice idea. Please share the info if you get it. There has been some controversy over naming your avatar.
The offline name is hardcoded in the .exe file.
Changing it is very easy, just search for the ASCII string "Explorer" in the NMS.exe file using any decent Hex editor (some advanced text editor might also work but I wouldn't recommend it) and overwrite the letters with the name of your choice.
If your name is shorter than "Explorer" you need to overwrite any existing letters of that string with NULL characters.
If its longer than "Explorer" you should be careful not to overwrite the data after that string, it seems like there is space for a maximum of 15 letters (excluding the final NULL character).
I can't guarantee if this works reliably or if any issues might arise with an existing savegame (at least your name in the menu screen changes properly) so you should be doing this at your own risk.
Also this is probably obvious but you'll need to redo this every time you patch the game (or if the .exe file gets updated).
And it might not work for the Galaxy/Steam version if the integrity of the file gets checked every time you launch it (but this shouldn't be applied to those anyway).