Pure, Frozen Water in Mars
Pure, Frozen Water in Mars 火星上发现纯净冰水!NASA has discovered evidence of water on the Red Planets surface. The finding, made by the Mars Global Surveyor spacecraft, fuels hopes that there may be life on Mars. 如今地球人在火星上发现了水，那么，火星人是否也要在不久的将来露出庐山真面目了呢？我们拭目以待更多更为伟大的科学发现！
Sources close to the Mars program said the discovery involves evidence of seasonal deposits that could be associated with springs on the planets surface.
NASA plans to make the blockbuster announcement during a press conference scheduled for June 29,sources said.
The discovery, if confirmed, would mark the achievement of a primary goal in NASAs program toexplore Mars.
NASAs ambitious plans forMars focus on gaining an understanding of the potential for either past or present life on the planet. The program also aims to improve sciences understanding of Mars climate and its resources.
Key to all three themes is water: Where and when it may have flowed in the past, where it might lurk today and in which forms and what quantities.
NASA scientists on the Mars Global Surveyor team declined to comment, pending the press conference and subsequent publication in the journal Science of a paper on thediscovery.
Ed Weiler, NASA associate administrator for space science, told the National Academy of Sciences Space Studies Board on June 14 that the Mars program needs a clear-cut vision. Thereal reason to go is to find out if life is there or not, he said.
"To meet that long-term mission requires that you follow the water. Without water there is notlifethere was not life," Weiler said. "By following the water, itall fits together. So for the first time, we have a really good, clear,long-term vision for Mars."
Water most likely flowed in the distant past on Mars, carving channels and other features clearly visibleon its surface. But other than in the form of clouds and ice, liquid water cannot exist on the planets surface today, thanks to the thinness of its atmosphere.
Scientists have hypothesized that vast stores of water could still persist beneath the surface of Mars.
NASA has suggested that certain martian features, as seen in this 1997 image, may indicate fluid seepage.
In a 1997 Mars Global Surveyor image, shown above, scientists proposed that water could have seeped from the walls of this unnamed crater in the planets southern hemisphere, and perhaps even pooled at the bottom of the impact basin.
At the time NASA originally released the image, it urged caution about adopting any one hypothesis explaining its details. Although the labeled version shown here listswater-related sources for the craters features, NASA stressed they could also be explained by the flow of lava.
Although the features could be explained by the presence of water, as in this labeled image, they could be volcanic in origin.
Finding water on Mars will likely put spurs into future mission planning: The American space agency will in upcoming weeks announce whether it will send an orbiter or lander spacecraft to Mars in 2003. (In 2001, it plans to send only an orbiter to the planet.)
"It's not like peopledont suspect there's water on Mars. We certainly know there was probably water in the past in fairly good quantities with all these older features," said Jack Farmer, an astrobiologist in the Department of Geology at Arizona State University, Tempe.
"But actually finding a place where water might make it to the surface, or at least some expression of it such as gases emitted into the atmosphere that would be a big deal,"he added.
The finding of upwelling water could mean striking biological pay dirt, Farmer said.
"In that situation,where you have water coming up from depth, into the surface, you might be replenishing the ground ice there on a fairly regular basis. Even if you never got liquid water to the surface you might be able to sequester organic materials, prebiotic chemistry or life, whatever, in the ground ice inventory,which you could access then by shallow drilling," Farmer said.
By finding liquid water near the surface, or actually part of the surface environment, "you could really move the whole question of searching for life ahead significantly, I think," Farmer said. "You could do some sort of shallow drilling program in a robotic sense, well in advance of any human missions," he said
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