this doesn't sound terribly plausible. I mean, it seems like a good idea, but think about it this way. Suppose you select an asteroid, get your space shuttle up there, and then start excavating. What do you do if you find the asteroid has some of the wrong kind of material inside, or something else is wrong? Scrap the mission and cut your losses?

If you can remotely investigate the meteor before you excavate it, then that means it's transparent to stuff like x-rays or gamma rays or high energy particles, something you can watch interact with the asteroid, and if it's transparent to that stuff then it can't protect the astronauts or payload.

How do you qualify your comments? As far as all I have read forever, they know the exact composition of these asteroids based on the light that passes through them.

There are plenty of reasons that this would never work but the radiation shielding aspect is quite solid.

im reminded of a certain scene in starwars...

Seems to me that, by the time you finished excavating an asteroid, you'd already have been to Mars and back... at least if they used the same calibre of construction crew, as are most roadbuilding outfits.

A mars mission is wasteful bullshit in any form. They need to get a working space station and then a colony on the moon.

here is an interesting read about such things.

If you could get the asteroid spinning a little you would have a 'rock and roll bus to mars'.