/sci/ - Science & Math

>>11849732
>>11849745
Simply by virtue of being on the ground you've already blocked 50% of radiation. In a crater maybe pushing 70%. Although it's a pathetic amount of atmosphere of Mars it's still adds some extra protection.
And then as you say all that's needed after that is regolith which you can get outside with a shovel.
There's simply no comparison between the two. If you can launch enough materials or generate an artificial magnetosphere in orbit you can do the same on the ground.