|
 |
|
Esta página no está disponible en español. Study: Moon Does Not Have Expanses Of Ice…Dashes Hopes Of Colonization…Building Moon Base
Study: Moon Does Not Have Expanses Of Ice November 12, 2003 The most exacting analysis yet of the moon's mysterious polar craters found no sign of the vast expanses of ice that scientists had hoped future lunar colonists could someday mine for precious, life-sustaining water. The findings do not mean there is no ice in the permanently shaded craters. But if there is ice, it is probably mixed into the lunar soil in widely scattered flecks or in thin layers. ``It certainly would have been nice to find some sort of lunar skating rink, or thick layers of ice, but it looks like it's just not there,'' said Bruce Campbell of the Smithsonian Institution's Center for Earth and Planetary Studies. He and colleagues at Cornell University used the mammoth radar dish at Puerto Rico's Arecibo Observatory to bounce radio waves off the craters. They probed more deeply than ever before into the craters' floors -- as far as 20 feet down in the soil. Like earlier Earth-based radar imaging that probed only a few feet below the craters, the latest analysis showed no sign of thick ice layers. The findings appear in Thursday's issue of the journal Nature. Campbell said the work supports the idea that any ice in the moon's polar regions is in thin layers or widely scattered crystals mixed in with the lunar soil. That, in turn, means that moon colonists would need equipment to either sort ice particles from the soil or heat up the crater floors and collect the water vapor. Five years ago, NASA's Lunar Prospector orbiter found tantalizing evidence that deep, dark craters at the moon's poles could harbor ice in their sunless depths. Prospector found elevated levels of hydrogen -- a component of water -- around the poles, with the highest readings in the shaded craters. But the evidence for ice was indirect. The moon's orientation means only about 20 percent of its shadowed polar craters can be probed by Earth-based radar, but Campbell said it is unlikely that large slabs of ice are hidden in the inaccessible areas. Astronomers have suspected since at least the early 1960s that the moon's polar craters, miles-deep with raised rims that help keep out the slanted polar sunlight, could have trapped ice from comets over billions of years. The temperature in some craters is about minus-280 degrees. Alan Binder, director of the Lunar Research Institute in Tucson, Ariz., said the only way to determine for sure how much ice is on the moon is to send a human or a robot. ``You've got to go down and stick your finger in it, so to speak,'' he said. NASA has no such missions planned. ********** On the Net: Center for Earth and Planetary Studies: http://www.nasm.si.edu/ceps/ Nature: http://www.nature.com
Water On The Moon? Scientists Await Definitive Answer By Rick Callahan of Associated Press November 12, 2003 INDIANAPOLIS - The latest effort by science to answer whether there's ice on the moon has come up empty. There's no sign of a lunar skating rink in the mysterious polar craters - or even a big slab of ice. The results of the most detailed radar study to date of the moon's shadowy poles don't mean the moon is bone-dry. But the apparent lack of large ice tracts suggests there isn't a big supply of life-sustaining water nearby if people ever wanted to colonize the moon. "It certainly would have been nice to find some sort of lunar skating rink, or thick layers of ice, but it looks like it's just not there," said Bruce Campbell of the Smithsonian Institution's Center for Earth and Planetary Studies. Five years ago, NASA's Lunar Prospector orbiter found tantalizing evidence that deep, permanently shadowed craters at the moon's poles could harbor ice in their sunless depths. Prospector found elevated levels of hydrogen - a component of water - around the moon's poles, with the highest readings in the perpetually shaded craters. But the evidence for ice was indirect. Subsequent experiments that bounced radio waves off these craters revealed no sign of thick ice layers, although those tests penetrated only a few feet below the surface. Now, Campbell and colleagues at Cornell University have used the mammoth radar dish at Puerto Rico's Arecibo Observatory to probe craters more deeply than ever before - as far as 20 feet down. And still there's no sign of thick layers of ice. Campbell and colleagues at Cornell University say their findings support the idea that any ice in the moon's polar regions is in thin layers or widely scattered crystals mixed in with lunar soil. The findings appear in Thursday's issue of the journal Nature. If the moon's poles do have widely dispersed ice, Campbell said that means moon colonists would need equipment to either sort ice particles from the soil or heat up the crater floors and collect the water vapor. Astronomers have suspected since at least the early 1960s that the moon's polar craters, miles-deep and surrounded by raised rims, could have trapped ice from comet impacts over billions of years. Temperatures in some craters hover at about minus 280 degrees Fahrenheit, forming "cold traps" where water could collect even as it escaped into space over the rest of the moon. Alan Binder, the director of the Lunar Research Institute in Tucson, Arizona, said the new results are consistent with the Lunar Prospector's findings suggesting widely scattered ice, perhaps a few hundred million metric tons of it. But the only way to know for sure is to send a human or robot. "You've got to go down and stick your finger in it, so to speak," he said. NASA has no lunar missions planned to address that question, but it is soliciting ideas for lunar spacecraft.
Lack Of Ice In Craters Dashes Hopes Of Building Moon Base By Charles Arthur, Technology Editor November 13, 2003 (c) 2003 Independent Newspapers (UK) Limited . All rights reserved. This material may not be published, distributed or exploited in any way. HOPES THAT man could set up lunar bases by exploiting the ice that is left behind by smashed comets and asteroids may be dashed. Research now suggests the Moon has little usable water. Futurologists had believed there might be plentiful ice on the Moon that could be mined to support human life. Surveys by a Nasa spacecraft in 1998 suggested there was between 11 million and 330 million tons of ice dispersed across about 25,000 square miles at the satellite's poles. However, a team from the Smithsonian Institute in Washington has carried out radar surveys of craters which never see sunlight and should be the ideal place for ice to gather. They found, disappointingly, that any deposits must be in the form of "distributed grains or thin layers". The research, published today in the science journal Nature, does not put a figure on the amount - although the dispersed nature of any ice would probably put the figure at the lower end of the 1998 estimate. Having water already on the Moon would simplify the process of building a base, because it is so expensive - in rocketry terms - to transport water from the Earth. It is virtually incompressible, and every kilogram of water carried from Earth will use up many times its weight in rocket fuel, as well as pushing out other important items. Dr Ian Crawford, a lecturer in planetary geology at Birkbeck College in London, said: "Water is useful for three reasons: you need it to drink, you can split it using electrolysis powered by sunlight to get oxygen to breathe, and you can recombine its hydrogen and oxygen to create a rocket fuel. Any water at all is extremely helpful if you're setting up a Moon base." The researchers used a radio telescope based at the Arecibo Observatory in Puerto Rico to observe what sort of signals bounced back from the bottom and the edges of craters on the Moon, and compared those with signals from craters on Mercury that are thought to have thick layers of ice. But whereas the craters on Mercury gave one form of reflected signal, those on the Moon did not, even using wavelengths that could probe several metres down into the lunar dust. "Thick deposits of ice ... are not observed within the crater floors visible to the Arecibo system," note the researchers. The only way that could be true, while also confirming results from Nasa's Lunar Prospector mission - which in 1998 detected the presence of ice by the scattering of neutrons - is if the water ice is present as grains amid the dust, or in thin layers. Dr David Rothery, of the department of Earth Sciences at the Open University, said: "I would have been very surprised if there were large sheets of ice. This finding does make colonisation of the Moon that much harder. You could extract it; it's still feasible to get water on the Moon if you want it badly enough." Dr Crawford said: "It would be better if there was a lot of ice, but even if it's present at just 1 per cent, then by taking 100 kilograms of lunar soil and heating it to 100C, you'll get 1 kilo of water as steam. We could have a small base with a handful of people; they wouldn't need much water." He insisted there were still important reasons, both scientific and political, for setting up a permanent Moon base. "Most contemporary planetary science is built on the legacy of the Apollo programme from more than 30 years ago," he said. "And there are geopolitical reasons to go again - we need something that would unite us. Plus, when there's a space race on, then the arms manufacturers tend to make spacecraft rather than arms - and that's got to be a good thing for all of us."
|