Mark, I understand mass=protection - that's not the problem -

If you want to live underground you can do it here on Earth - the problem is exposure times on Mars, if you're talking about either human explorers or colonists. And then you have to consider the thickness required for any clear domes needed for agriculture - and shielding in surface vehicles - and suit mass -

(By the way, the Apollo moon suits were way massive, and that's in 1/6 Earth gravity, not the 1/3 gravity of Mars - given the similarity in conditions, I don't think that a Mars suit can be made much lighter than the Moon suits were... in other words, it may be possible that no suit can be designed so that people can work on the surface of Mars - but that's another issue)

I reported what the symposium participants thought and said. The two whose comments I reported were both professionals who are intimately familiar with the data on Mars' radiation...

Now if you can dig up detailed data showing otherwise I won't have to do a re-write on some sci-fi I have sitting around - and there are other Conference participants who would also be delighted to hear of it...

EP