The main reason is that Mars is a very unhealthy place, not just for humans but for all life. Forget the temperature extremes. The biggest problem with Mars for maintaining life is that it has almost no protection against radiation. It has no iron core like Earth and thus it does not have the magnetic field that protects humans from cosmic rays and solar mass ejections.
Read this article for more information.
Six feet of soil can shield against cosmic rays as can a few centimeters of water. Since hauling water to Mars hardly seems practical, unless an ample water supply is found on Mars, the "explorers" will have to be satisfied with living and exploring under the surface.
Also, the human body is so adapted to our level of gravity that almost absent gravity (as in the space station) damages bone density. In a large space craft that rotates, you can use centrifugal force to simulate gravity, but how do you do that on the surface of Mars? Not exactly a vacation and no place anyone would want to live for long.
Terraforming isn't practical unless there's a way to give the planet a magnetic field. Otherwise, the atmosphere will simply be lost to space.
What do you think?
You go ahead, I'll be along shortly --
Why would you expect the universe to have an edge?
The same reason we would assume the world has an edge... we can see it everyday, it's called the horizon.
you're thinking too short-term. the idea isn't to have humans colonize Mars, but one of our evolutionary descendants or cousin/nephews (yes, a long time into the future). Here's my version of the plan: we set up biodomes imitating climates on other planets (bombarding them with solar-type radiation if necessary), then put earthling bacteria in them, to live or die. Over a very long time (and lots of dead organisms), they evolve to be suited to that climate. Then we send probes over with bacteria cultures. Lots of them, since most won't survive. Then we wait a few eons, and voila! Intelligent life elsewhere in the solar system. Not to mention, if earthkind gets wiped out dinosaur-style, we will have spread our earthling seed elsewhere. Evolution!
plus, even if colonization never happens, science happens! think of the wonderfulness of the discoveries, even if they are practically useless!
Andrew - there are some who think that scenario may have happened already, ergo -- us!
Are we so wonderful that we need to "spread our seed" elsewhere in the galaxy or universe? Suppose that compared to the other intelligent life, we actually qualify as a plague! Elsewhere in this thread someone suggested that dollars are the main reason for exploring Mars. Who knows how much it may have in gold, lithium, or titanium?
Maybe it turns out that WE are the aliens who arrive at some peaceful planet intending to rob them of their natural resources!
Of course, that would be far off in the future, but clearly we are capable of that.
RE: "Suppose that compared to the other intelligent life, we actually qualify as a plague!"
There are some who meet that qualification now.
Then we wait a few eons, and voila! Intelligent life
A FEW eons? how long is an eon anyway? To go from bacteria to humans on earth it took 3.5 to 4 billion years I believe...
Yah, and look how smart we became..;p(
For the first humans migrating out of Africa most places on Earth were uninhabitable, and yet in time, many of these places came to be inhabited. Could this first tribe of humans have survived in Greenland? But are there are not people in Greenland now? What made a previously uninhabitable place inhabitable later on? Technology! Could the early humans have conceived of this technology? No, but it did come to be realized. What was true of Greenland could be true of Mars as well.....in time! Our inability to presently conceive of how we can live on Mars should not prevent us from thinking that such a thing should one day be possible.
One might say, well Greenland had some life on it, albeit non-human and Mars had no life on it, and that is the difference! Well, surely that non-human life had its origins in some place other than Greenland, yet it eventually came to inhabit Greenland, so that argument is not a good one. Besides, no living creature other than humans ventured out into space. Space is completely, utterly lethal to all life forms on this planet, but humans still managed to venture out into it with the aid of technology. What is it about inhabitation that makes it very different from visitation? Nothing really. Any difference is essentially parochial! Therefore, just as Mars could be visited by a piece of human technology, so also should it be visitable one day by humans. And since there is no real distinction between visitability and inhabitability, Mars will one day be inhabited by humans (or trans-humans)! That is my argument.
You're aware that Africans didn't suddenly find themselves in Greenland right. The drift was slow. They occupied and adapted to the next area's slightly different climate zone and feeding opportunities over a long period of time. Long enough for naturally selected adaptive traits to occur.
Besides, the conditions on Mars can't be adapted to biologically. It is a poisoned, lethal place. Any earthly life there will be living underground or under water.
If you read the subject line, I'm not saying we'll never go to Mars, just that we'll never colonize it. By colonizing, I mean a permanent population, not a population of people sent there and returning on rotation,
There is quite a lot of water on Mars. "NASA scientists calculate that the volume of water ice in the south polar ice cap, if melted, would be sufficient to cover the entire planetary surface to a depth of 11 metres." (Wikipedia) There is also the northern icecap, and possible underground water. I read recently that Elon Musc is planning to send colonists to Mars, if anyone can do it its him.
It should be added that the solar radiation argument isn't particularly strong. If we send people in their 40ies or 50ies to build habitats, a higher lifetime potential for cancer and other radiation caused diseases isn't a particularly acute danger. They may get cancer at 75 instead of getting cancer or experience cardiovascular issues at 80, which is a price some may wish to pay.
It's also not a particularly well understood problem: http://en.wikipedia.org/wiki/Health_threat_from_cosmic_rays#Human_h.... Note the substantial use of qualifiers: potential, most likely, likely, incomplete, collect more data, estimates, limits advised, poorly known, etc.