While it has been speculated that microbial life may exist elsewhere in the solar system such as Mars or Europa, only on Earth are the conditions habitable for complex life. If humans were to go to Mars now, they could not walk freely on the surface. Despite what is depicted in much of science fiction, humans could not get by with just a breathing apparatus and a warm coat. The atmosphere is so thin that a full spacesuit would be required. Explorers would need to live inside a pressurized, heated structure, be it the spacecraft in which they arrived or a habitat they built. Eventually colonies might develop. Entire cities could be build under giant domes inside of which would be Earthlike conditions.
The colonists in these domes would live forever enclosed. Few humans can endure such conditions for long periods of time. Even in the relatively hosptitable environment of Antarctia, scientists at the South Pole Station suffer claustrophobia. And these people can venture out of doors and stay for less than a year. Launch windows between Earth and Mars occur only once every two years, and on Mars there is no outside air to breathe.
The true dream of space explorers is terraforming, changing the environment to be earthlike. This is not such an outlandish goal; it's been done at least once before -- on Earth. The primeval atmosphere of Earth was rich in methane and carbon dioxide with virtually no free oxygen, a place totally unsuited for animal life. Two billion years ago that all changed as photosynthetic organisms produced oxygen, creating the atmosphere we know and breathe today.
Mars is the next best candidate. It lies within the Habitable Zone and may have at one time had water flowing on its surface. If terraforming happened once, it can happen again. Especially if we help it along.
Why Mars? In the Volatile Content page, I describe exactly what Mars has to offer, and why it isn't suitable for complex life now. In the Atmospheric Evolution section, I describe how it started and what changed it to its current state. The Goldilocks paradox is also addressed and Mars's evolution is compared with Earth's."
However, as with so many problems, there is more than one interpretation. I will mention the White Mars model in which carbon dioxide played the part of water on early Mars and no liquid water is ever required.
The Terraforming section contains information on what changes need to be made to Mars in order to make it Earthlike, and addresses the tecnological issues associated with it. The Planetary Protection page discusses how terraforming may affect any indigenous microbes, and how they may affect us.
Understanding the Martian atmosphere and how it relates to Earth is critical for establishing a human civilization on the Red Planet and for continued space exploration.
These pages designed by James
Roberts
Last updated: 06 May 2002
http://anquetil.colorado.edu/~jhr/terraform/intro.html