Even setting aside that it's 95% CO2 and incredibly cold, most people have no appreciation for how thin the Martian atmosphere is. Surface pressure is 0.6% tha

Even setting aside that it's 95% CO2 and incredibly cold, most people have no appreciation for how thin the Martian atmosphere is. Surface pressure is 0.6% that of Earth, with maximum density 2% that of Earth's. It's not like Martian explorers could get away with just a respirator.