Projects to Employ Resources of the Moon and Asteroids Near Earth in the Near Term
Lunar Prospector home page
Lunar Ice Discovery Home Page
The ice probably arrived as a comet -- which exists mostly of water ice -- that plowed into the Moon. As there is little or no sunlight in craters at the South Pole it remained there in a frozen state. It was estimated to be about 8 metres thick and to have the size of a small lake or pond.
Well, there was in fact no news under the Sun. The discovery of ice at the lunar South Pole was already foretold in the Dutch travel guide De Maan which was published March 1993 -- long before Clementine entered lunar orbit. This travel guide was translated into English and published February 1996 as the Moon Handbook: A 21st-Century Travel Guide.
Anyway, Clementine discovery of ice on the Moon and its March, 1998 corroboration by Lunar Prospector means a major impetus to return to the Moon! So have a look at the above mentioned travel guide and be sure to book your future trip in time!
The news on Clementine's original discovery was reported on CNN.The full scientific story can still be read on-line in Science magazine
Full explanation and various links to related subjects were reported by the December 4, 1996 Astronomy Picture of the Day.
An illustrative picture of the lunar South Pole -- with the areas containing ice painted red -- can be found on Sky & Telescope's Weekly News Bulletin of December 6, 1996.
From "Moon Handbook: A 21st-Century Travel Guide" (February, 1996):
The dark parts of Amundsen are the coldest on the Moon. But a great deal
of activity goes on here, for this is where American and Japanese
robot prospectors discovered a nearly inexhaustible supply of ice in
1997. Two months after the Lunar Prospector of NASA and the Space
Studies Intstitute in Princeton came across the ice, the Japanese sent
their Lunar A to the Moon to investigate further. It plunged a probe equipped
with scientific instruments into the site, and it relayed a complete chemical
analysis back to Earth. The analysis confirmed the presence of ice.
As water can be broken down into oxygen and hydrogen, the discovery of ice meant that these two gases no longer had to be transported from the Earth to the Moon. Of course it was long known that oxygen could easily be extracted from lunar rocks. But lunar rocks contain little or no hydrogen, and a mixture of oxygen and hydrogen is needed to produce a high-grade rocket fuel.
The discovery of ice provided the impetus for the joint Return to the Moon project. Several years later, in the year 2000, Earth's space agencies launched the International Lunar Quinquennium, a five-year program proposed by the Europeans. The program tested key technologies ans sent a host of scientific missions to the Moon. The Moon was settled beginning in the year 2009, and Amundsen's ice is distributed to water-processing plants in the lunar bases and to the factories in Moon City that produce rocket fuel.
Long ago, a comet consisting predominantly of ice must have crashed here. In the eternaly dark Amundsen Valley, the ice never felt the heat of the Sun, but awaited the arrival of humankind.
A revival of lunar exploration came unexpectedly with the Clementine
mission to the Moon. Clementine, an unmanned spacecraft that orbited the
Moon for 71 days in 1994, was a military mission that piggybacked astronomical
experiments. Clementine recorded about 1.5 million images in 11 visible
and near-infrared colors. A mosaic of 1,500 images of the lunar South Pole
was particularly intriguing. it revealed for the first time a depression
four billion years old and 2,500 km wide near the pole.
The depression is christened the South Pole-Aitken Basin. Within the basin is an impact crater 12 km deep - more than seven times as deep as the Grand Canyon - and 300 km wide. It's by far the deepest impact crater in the solar system.
Part of the basin stretches to the South Pole itself. There, at Amundsen crater and the Mountain of Eternal Light, sunlight never penetrates. Since it remains at a frigid -230°C, it became a perfect icy storehouse for water that comets brought to the Moon.
"This is the place on the Moon where you would go to get ice for your cocktail," joked Clementine investigator and geologist Eugene M. Shoemaker when he saw the photographs.
Later missions did find ice deposits, though they were too dirty for immediate use in cocktails. But after purification the ice proved to be a most valuable source of drinking water. The ice's oxygen and hydrogen molecules are also used in the production of spacecraft fuel.