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?
Early 70's, our high school had a visiter to the science department that was researching the use of radiation for food preservation. During that talk he mentioned the discovery of a bacteria that could survive very high radiation exposures. The bacteria was red, and if memory serves, produced a mercaptan like compound in the cell membrane that had a very large shielding capacity. I think the reseacher's name was Jessy Bone, of OSU. He also said that he was a science fiction writer. He mentioned that his last book was titled 'Nobel Red Man'.
I did some Googling and didn't find anything hopeful in regards to mercaptan and radiation shielding for humans. Anyway, if the radiation didn't kill ya, the low gravity would.
The memory was from about 40 years ago, but it 'felt' ok when I wrote it. It is doubtful that Dr. Bone is still alive, and I don't know if his work has been classified or just an interesting little datum.
I find it interesting that no permanent, self contained, sealed human environment has ever been constructed on this planet, how can we expect to do so on another?
Well Obama is not convinced with the plan for a man mission by 2030. That all will change depending on the outcome of the next election. The absence of an iron core does preclude terraforming outside an enclosure. Thus enclosures must be built to maintain biospheres. Glass could be manufactured on the planet to create enclosures over creators. Glass enclosed craters have been observed on the moon, albeit, natural (or maybe unnatural.)
Mars does not have a steady precession like earth. it has an erratic wobble which could wreak havoc on any seasonal dependencies.
But what is motivating missions is the search for extraterrestial life. Carbonate in former water basins would suggest life in the past.
Michael! Good to see you participating in a purely secular discussion. Bienvenido!
All of the things that could provide aid and succor to people on Earth, in the probably vain attempt to determine if there's some bacteria below the surface of Mars.
Get real, masses of people in Europe were starving when the expeditions that resulted in the discovery of the Americas was financed, we are explorers, and financial gain has always been the bottom line.
YES, you are right on the ball my friend