[muir_redwoods]

Why would you need several feet of lead for radiation protection? Surely an inch or so would be more than adequate and more sophisticated shields would require even less.

How does the space between Mars and Earth differ dramatically from the space between Earth and the moon? How about the people who spends months in the orbiting space stations?

Do you seriously feel that such a trifling problem will keep us away from Mars? Really?

[gore3000]

Why would you need several feet of lead for radiation protection?

We don't need it. We did go to the moon and had no radiation problems. The spacecraft had such thin sides that the astronauts could have punched a hole in them if they had been stupid enough to try.