Lunar Ice

Clementine Data Suggest Moon Harbors Ice

Special to Space News

LOS ANGELES--Scientists poring over data transmitted last year from the Clementine spacecraft as it orbited the moon believe they have found water on that barren world. The discovery, they say, could have a profound impact on future lunar exploration plans.

While orbiting the moon, Clementine scanned the lunar terrain and returned to Earth nearly 2 million separate images, observing the moon uniformly in 11 different wavelengths with its sensors. Following a year of study, data gleaned from the spacecraft's radar sweep of the moon's south pole region suggests it is the site of water in the form of ice, said U.S. Air Force Col. Pedro Rustan, the former Clementine mission manager at the Ballistic Missile Defense Organization (BMDO). Rustan is now director of small satellite systems in the Office of the Secretary of the Air Force for space technologies.

"The data strongly suggests the presence of ice," Rustan said Oct. 7 at the Space Frontier Foundation's Frontiercon 4 conference. Radar pulses transmitted by Clementine and reflected back from the moon's large south pole basin are indicative of water ice. "The data looks very encouraging," Rustan said.

Eugene Shoemaker, scientist emeritus with the U.S. Geological Survey in Flagstaff, Ariz., told Space News that complete details of the Clementine finding are being submitted to Science, a professional scientific journal, for peer review and publication. Shoemaker coordinated the Clementine imaging program.

While cautious in not disclosing particulars of any Clementine water ice observations, Shoemaker said the finding of such a reservoir would open the door to utilizing the moon as a stepping stone for deeper space exploration.

"An easily extractable reservoir of water ice can be used not only at a base, but by hydrolyzing water you've got rocket fuel. You could then really think in terms of the moon as a staging area," Shoemaker said.

Paul Spudis, a staff scientist at the Lunar and Planetary Institute in Houston, said that from a scientific point of view, the detection of water ice on the moon is not startling. "However, from a space development, and a human space travel point of view, it is an enormously significant discovery,'' Spudis said in an Oct. 9 phone interview.

"Even after Clementine, we're not going to know for sure if ice is there. You need to follow that up with another mission to really confirm if it's there and how much of it is there," Spudis said.

The 500-pound spacecraft we built for BMDO by the Naval Research Laboratory and designed to test lightweight sensor hardware that might be useful for ballistic missile defense.

The large basin at the moon's south pole is considered by Clementine scientists to be a likely locale for water ice. Deep craters there are permanently shadowed from the sun's warming rays and could hold ice from comets that struck the moon long ago.

At the rim of that same basil area, a range of mountains jut high into the lunar sky. "Some spots on the summits of those mountains are in permanent sun shine. That's an advantage as you can draw solar power all the time," Shoemaker said. A source of solar energy near a source of water ice has a range of potential applications, he said.

"You can let your imagination go a little bit . . . you can see what the possibilities are," Shoemaker said.

John Lewis, professor of planetary sciences and co-director o the Space Engineering Research Center at the University of Arizona at Tucson, was somewhat less convinced of the significance of the discovery. The Clementine data "is extremely tantalizing,' he said, "but whether it can be unambiguously linked to water remains to be seen." Lewis also said any water ice at the moon' south pole "is sort of in the wrong place." Hauling water to more equatorial lunar bases would be expensive and a logistics problem, he said.

"I think people are going to have to think really hard about how to use that water [at the lunar south pole]," Lewis said. "My calculations lead me to view that [finding water on the moon] is a rather marginal bonanza," said Lewis, adding that the scientific information about ice at the pole might exceed the economic value.

Again, opinions differ greatly. Philip Chapman, a former NASA astronaut now with the Center for Enterprise in Space of Scottsdale, Ariz., told conference attendees that lunar ice could be worth as much as $9 trillion, when calculating its value for life support, energy storage, agriculture and industry at some future lunar base.

Chapman said rules should be formulated governing the rights to lunar ice. Furthermore, the U.S. Lunar Prospector mission that will begin orbiting the moon in a few years should not provide treasure maps for U.S. rivals in a possible cold rush, he said.

Shoemaker said the Clementine spacecraft also has provided a wealth of data on the moon's composition useful in determining its origin. He said information from Clementine argues that the moon is not a piece of the primitive Earth as some scientists have theorized in the past. More likely, the moon is leftover material from a very large body that hit the Earth in the past.

"Something about the size of Mars hit the Earth and . . . was left as debris in orbit around our planet" to form the moon, Shoemaker said.

Reprint courtesy of "Space News"
Copyright by Army Times Publishing Company
Springfield, Virginia


Wednesday, 31-Dec-1969 18:00:00 CST