Mars and Antarctica

One of the loopier ideas that regularly makes the rounds is colonizing Mars.  For one thing, a few individuals with more money and notoriety than sense are proponents and are able to keep drawing attention to the concept.  The most fundamental objection, of course, is that no one has ever been able to think of a convincing reason for sending humans to Mars.  Collection of scientific data can be (and is being) done far more cheaply and safely by machines.  No resource available on Mars would be worth the staggering cost of transporting it back to Earth.  As for the claim that we need a human population somewhere else to guarantee species survival in case something happens to Earth, I addressed that nonsense here.

To understand why colonizing Mars is never going to happen, look at Antarctica.  It's the only continent humans have never colonized in the sense of establishing a permanent self-sustaining population (though there are a few small bases there).  Why not?  Obviously, because the environment is too inhospitable.

But compare Antarctica with Mars.  Yes, Antarctica is cold, but Mars normally gets even colder at night.  Antarctica is somewhat remote, but Mars never gets closer than forty million miles away.  The cost of travel to Antarctica is not prohibitive.  NASA estimates that a manned expedition to Mars -- sending a few people for a brief stay, comparable to the Apollo Moon missions -- would cost $450 billion (yes, with a B).  That's two-thirds of the annual US military budget.  It's more than the annual economic output of most countries.  Now imagine what it would cost to set up a permanent colony.  Then imagine what voters would think of diverting such vast sums to that endeavor, given what the same money could accomplish if applied to ongoing problems on Earth.

Antarctica has breathable air and Earth-normal gravity, and while some dream of changing Mars's atmosphere to make it more Earthlike (a far from simple or easy process, if it's even possible), we will never be able to change its gravity.

Gravity is important.  There have been cases of astronauts spending periods of up to a year in zero gravity in space, and we know that it causes several serious health problems, such as vision disturbances and loss of bone and muscle mass.  Mars's surface gravity is only one-third as strong as Earth's.  Given the problems caused by a few months in zero gravity, it seems impossible that an entire lifetime lived in Martian gravity wouldn't also have serious detrimental effects.  For example, if pregnancy (a stressful process even under ideal conditions) cannot proceed normally in Martian gravity, then humans will never be able to reproduce naturally there.

The only solution I've seen proposed for this problem is to build human habitat inside a huge permanently-spinning wheel so that centrifugal force would mimic Earth's gravity.  This might work for a small base comparable to those that exist in Antarctica, but it would be completely impractical for the normal towns and cities which talk of "colonizing Mars" implies.

Carl Sagan was right.  "Like it or not -- for the moment, the Earth is where we make our stand."

Humans have managed to live permanently and even thrive in environments as hostile as the deserts of Arabia and Australia or the highlands of Tibet and Peru.  We have not done so in Antarctica, not even with modern technology, not even in the fringes of the continent which have exposed soil (not ice) which could conceivably be made arable.  If we haven't done it there, we're not going to do it on Mars either.