Reaching for the Moon - Does the discovery of water pave the way for lunar colonists?
点击量： 时间：2018-02-19 07:02:03
By Mark Ward LUNAR launch pads. Manned bases. Holidays on the Moon. Speculation is rife following NASA’s announcement last week that up to 300 million tonnes of ice could be lurking in the dark craters that pockmark the Moon’s poles. The discovery could transform the economics of lunar settlement and of further exploration of the Solar System, experts agree. But they warn that the difficulty of extracting useful quantities of water means that any permanent human presence on the Moon is decades away. Any future Moon base would recycle nearly all its water (see “Rice with everything…”). The main use for the lunar ice would be for separation into hydrogen and oxygen to make rocket fuel, says Mark Duke, staff scientist at the Lunar and Planetary Institute in Houston, Texas. “This would make the operation of a lunar base much more efficient,” says Hermann Koelle of the Technical University of Berlin, chairman of the International Academy of Astronautics’ subcommittee on lunar development. The running costs of a base, including fuel for round trips, could be cut by 60 per cent, he says. But Francis Rocard, Solar System mission manager at the French space agency CNES in Paris, warns that no one has accounted for the start-up costs. “If you take into account all the infrastructure you have to put on the Moon to make it work, it makes it much more expensive,” he says. Koelle agrees: “It takes a lot of equipment and manpower to establish a factory to produce propellants.” The ice is thought to exist as crystals making up less than 1 per cent of the top metre or so of the ground in some permanently shadowed craters. In theory, it could be harvested simply by shovelling up the soil, putting it in a sealed collecting system, and heating it. The main problem is the location of the ice. A manned base is most likely to be built in a sunny region near the lunar equator—nearly 3000 kilometres away from the polar craters that contain the ice. The logistics might change, however, if a base could be built at a crater rim near the lunar south pole called the Peak of Eternal Light. This area, just a few kilometres across, is thought to be permanently illuminated. Although the temperature never rises above –30 °C, a base could be heated by solar power. The European Space Agency was already planning a mission, called EuroMoon 2000, to put a lander on this peak. Delays mean that the earliest launch date will be 2001, but the proposal includes a tethered robot that will dart off into the permanent shadows of nearby craters to look for ice. Another problem is that the craters involved are some of the deepest on the Moon. Any robot sent to mine them might have trouble climbing back up the crater walls when fully loaded. But Red Whittaker, a roboticist at Carnegie Mellon University in Pittsburgh, is eager to meet the challenge. Last year he sent a proposal to NASA for such a rover, which he now intends to resubmit. Whittaker was one of the developers of the prototype Nomad robot,