Click on image for full size
NASA
Related links:
Headlines declare (12/2/96): Ice patches seen on Earth's moon
Radar images of the Moon's surface taken by American Defense Departments's Clementine lunar probe have pointed to the possibility of finding water on the Moon. The images of the Moon's south pole region show a patch of ice about 16 feet thick and roughly the size of four football fields.
"People had speculated since the early 1960s that ice might collect in the permanent shadow of the Moon," said Dr Stewart Nozette, an astrophysicist at the Lawrence Livermore Laboratory and head of science team on the Clementine spacecraft program. "We realized that we could use the spacecraft's communications antenna to shine like a flashlight into the lunar south pole. Ice reflects radar waves differently from rock, bouncing it around inside the frozen water molecules before it emerges."
One theory suggests that the source of ice was a comet which hit the Moon's surface some 3.6 billion years ago. Water from the icy comet was collected in the bottom of the crater where temperatures fall as low as -230 C. Because moon has no atmosphere, comets which are nine tenths water, do not burn up as they approach its surface. Upon impact with the Moon's surface, gaseous matter from comets hangs around as a cloud. Water molecules from this cloud get trapped in extreme cold regions, finally depositing as ice. The scientist now theorize that vapor from comet impacts drifted towards the pole where it got trapped in extreme cold and turned into ice.
The possibility of finding water on the Moon's surface has stirred speculations that by 2046 humans may be able to colonize the Moon or set up a lunar rocket refueling station. Using electric power provided by solar panels on the crater's sunlit rim, mined ice could be split into hydrogen and oxygen to provide rocket fuel, or to make your own air.
"This may be the most valuable piece of real state in the solar system," said Paul Spudis, one of the scientists who made the discovery.
If the Moon could be used as an interplanetary filling station, it would reduce the cost of transport to and from it by a factor of 10. It would make space exploration easier by relieving the problem of limited fuel and food which is one of the major obstacles in today's space missions.
The discovery was made two years ago (~1994), but was hushed until now as the data were being analyzed. The evidence of water was collected by a satellite designed to test technology for tracking and intercepting hostile missiles. The Clementine mission used the Moon as a mock target to test missile sensor equipment, but during its two-month lunar orbit it collected 1.8 million images of over 99.9 per cent of the Moon's surface. Six visits to the equatorial region of the Moon by Apollo spacecraft turned up no trace of water. Twelve astronauts, all from the U.S., have walked on the surface of the moon, which is about 239,000 miles from the Earth.
