Mars
...advanced. When ground-based telescopes gave way to visiting spacecraft, the myth of intelligent beings on Mars disappeared, and new mysteries evolved.
As the most Earth-like planet, Mars has held special interest, in that it is the most likely place in the Solar System that could have supported at least primitive life. So leaving aside little green men, or H.G. Wells' depressing creatures in The War of the Worlds, the question is posed: "Was there life on Mars?"
Even with the discovery over the past decade of the flourishing of life in extreme environments on Earth, the presence of liquid water remains a prerequisite. So to answer this most profound question, the current space missions have been designed to search for evidence of water on Mars.
There have been many hints, and more recently, evidence that is almost irrefutable, that water existed on the surface of Mars. But, until now, it was unclear whether liquid water was there billions, millions, or tens of thousands of years ago, or even in recent decades.
On Dec. 6, scientists described a discovery made through an intensive effort to compare images of Mars over time taken by the Mars Global Surveyor orbiter. The results led them to conclude that there is liquid water underground today on Mars, which periodically spurts up to the surface.
The high-powered Mars Reconnaissance Orbiter, which has just begun its science mission at Mars, along with the in-service European Mars Express, are using radar to search for reservoirs of ice and/or liquid water under the surface of the planet. More surprises can be expected.
The Long Road to Mars
Two centuries ago, using ground-based telescopes, astronomers could see shades of light and dark material, somewhat fancifully interpreted as structures made by intelligent life forms. Periodic changes in the surface features of Mars led to the idea that...
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