for National Geographic News
As rovers and orbiters continue to scour Mars for more signs of water and the potential for extraterrestrial life, space scientists and enthusiasts are champing at the bit to put humans on the red planet.
In recent months, spacecraft roaming and orbiting Earth's closest neighbor have identified regions where large supplies of water may be accessible from the surface. They have also located areas where gases such as methane could support oxygen-producing bacterial life.
Such discoveries are raising the possibility that life lives on Mars today, did so in the past, and with the help of humans, could do so in the future. To find out for sure, space scientists and enthusiasts say humans need to travel to Mars.
"There's no question we'll ultimately go there. It's a matter of when, not if," said Lynn Rothschild, an astrobiologist at the NASA Ames Research Center in Moffett Field, California. (Astrobiology is a branch of biology that searches for extraterrestrial life-forms.)
Robert Zubrin is the president of the Mars Society, a Colorado-based organization that promotes human exploration and settlement of the red planet. He said the technology exists to put humans on Mars within a decade.
"We are much closer to being able to send humans to Mars today than we were to being able to send men to the moon in 1961, when [United States President John F. Kennedy] started the Apollo program," Zubrin said.
Under the leadership of Kennedy, humans first set foot on the moon July 20, 1969. Given similar visionary leadership, Zubrin said, humans can walk on Mars within the decade and begin the process of colonization.
The surface temperature of Mars is 81° Fahrenheit (63° Celsius). The planet is bombarded by ultraviolet radiation, and its atmosphere is about 95 percent carbon dioxide.
While such conditions are less than ideal for Earthlings, there's "nothing about Mars today except [ultraviolet] radiation on the surface that would preclude life from surviving there," Rothschild, the NASA astrobiologist, said.
Any life would need to be shielded from the high levels of ultraviolet radiation on the surface and presumed oxidants, she added.
Rothschild noted that surviving is different from thriving, multiplying, and spreading. For humans to thrive on Mars and to have a continued presence there, they will need to transform the atmosphere and climate to suit human needs: The atmosphere needs to be full of breathable oxygen and the climate warm enough for liquid water.
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