The U.S. space agency, NASA, plans to crash a rocket into a crater on the south pole of the moon on Friday in hopes of detecting water in the debris produced by the impact. An empty rocket will slam into the lunar surface followed by an inspection by the Lunar Crater Observation and Sensing Satellite or LCROSS, which will later also slam into the moon. If the probe shows the presence of water, it could boost U.S. plans to establish a lunar base. But finding water on the moon is only the first step.
The LCROSS mission is being watched with great interest by manned exploration planners at the Johnson Space Center here in Houston. The probe's mission is to find out whether there is water in deep, dark craters near the moon's poles that could be used by astronauts at a lunar base.
Such a plan is part of NASA's Constellation program, whereby bases on the moon would be used for launching more ambitious manned missions to Mars.
Wendell Mendell, Chief of Lunar and Planetary Exploration for the program says LCROSS is an essential first step.
"It is a bit of a crap shoot to see if we can do this. Part of the reason is there is not really any other good way to know exactly what is there. You have to, in some sense, go there," he said.
The theory being tested is that water, in the form of ice, has collected in deep craters in polar regions of the moon, where the sun's rays never reach. Water that might have come to the moon from comets, for example, would have been turned to vapor by the intense sunlight hitting most of the lunar surface. But Mendell says there is a good chance that there is some form of water in the craters.
"It is probably not really ice in that sense. It is probably minerals that have a water component to them," he said. "Then the water component has to be extracted from the minerals somehow. And probably, you want to do the extraction up near the base instead of down in the middle of the crater and so you have a transport issue," he said.
But Paul Spudis of the Houston-based Lunar and Planetary Institute, is optimistic. He works with NASA on exploration plans and says there might be water in a purer form.
If sufficient quantities can be extracted for use at a base near the top of the crater, Spudis says it could provide drinking water for humans and be broken down into hydrogen and oxygen.
"You can take water and pass an electric current through it that might be generated by a solar panel and then turn it back into its gaseous form as well," he said. "Now when it is in its gaseous form, it can be condensed into an extremely cold version, the cryogenic version, of liquid oxygen and liquid hydrogen, which is also a rocket propellant," he added.
Water also can be used in other ways to create energy. Fuel cells on the Apollo missions provided astronauts with energy and drinking water.
Spudis says there is yet another use for water on the moon.
"The other thing you can use it for is for radiation shielding. Water is a very good shielding material. It stops a lot of high-energy particles and you can jack your inflatable habitat with a water bladder that would effectively act as a radiation shield," he said.
Spudis says no matter what the LCROSS mission reveals, NASA will have to follow up with more missions, involving robotic rovers, to confirm the results and test the material in the crater.
"You can do a lot with robotic missions before people arrive. You can land and you can survey what the physical state of the stuff is," he explained. "You can even dig up soil and experiment with extracting it [water] from the soil and see how difficult that is. A lot of that can be done robotically because the moon is very close, so we can tele-operate machines that are on the moon from Earth with a minimal amount of time delay," he said.
In addition to the data that will be provided by the LCROSS spacecraft flying through the several-kilometer-high debris cloud created by the empty rocket crash, astronomers here on Earth will be watching the impact and looking for evidence of water. NASA's Hubble space telescope is also being directed at the moon for the event, so there should be a great deal of data to analyze after the experiment is over.