Nah you just need a bunch o rocks. Bombard Mars for 50 years with every chunk of rock and ice you can strap a couple engines and fuel tanks to, aka a used Stars

Nah you just need a bunch o rocks. Bombard Mars for 50 years with every chunk of rock and ice you can strap a couple engines and fuel tanks to, aka a used Starship second stage, and it’ll be plenty warm and wet.