LOS ANGELES, CA (Catholic Online) - Scientists are very interested in Mars for two reasons. First, the planet was once wet with large quantities of water flowing over the surface, but today it appears to be much drier. Certainly, nearly all of the surface water is gone, both evaporating into space and seeping into the frozen ground. What little remains is locked in the polar caps and in pockets of underground ice. Why this happened, and what are the implications for Earth is an important question, if we can answer this, then we can better understand the Earth.

The second reason is to ask if Mars can support human colonization sometime in the future. If water still exists on Mars, then where can it be found and can it be extracted to support colonization? It is thought by scientists that at some point, the future of humanity lies amongst the stars. To prepare the way, pioneering work must be done. This is part of that work.

Incidentally, the search for life is more of a secondary quest, with the best hopes being that some form of microbial life once existed on the planet during its warmer, wetter past. However, the likelihood of such a discovery varies from virtually nil to almost certain depending on which scientists are asked and their perspective on the data. Nonetheless, this is not the primary focus on Mars.

The great "river-like structure" as scientists describe the canyon in the image, is Reull Vallis, a broad, dry river flanked by ancient bluffs. Measurements suggest the river would have been 4 miles wide and as much as 1,000 feet deep, meandering for 900 miles before empyting into the vast primeval Hellas basin.

The river, like any other on Earth, was fed by smaller tributaries, which also appear in the high-resolution photographs. They also say the region shows evidence that it was once covered with glaciers.

Water likely flowed though Reull Vallis somewhere around 3.5 to 1.8 billion years ago, before Mars finally became a dry planet. Mars didn't become dry all at once, but gradually lost its surface moisture and became cold over a long period spanning millions to billions of years. Why this happened remains a mystery.

For scientists, seeing that Mars had a more Earth-like climate than previously thought encourages them to redouble their research. Dedicated as ever, they hope to decipher to the silent testament of Mars's dry rivers and to learn what they have to say about Earth's future. 

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