Ice on Moon? It Could Open Solar System

Plans to make the moon into an orbiting laboratory for space exploration suddenly seemed much closer to reality with this week’s announcement that frozen water may have been found deep inside a crater on the moon’s frigid south pole.

At a Department of Defense-sponsored news conference in Washington on Tuesday, Rice University’s Paul Spudis called the crater “possibly the most valuable piece of real estate in the solar system. It’s certainly a place we can go . . . and live in an area that’s actually benign environmentally on the moon.”

A base at such a location would mean that scientists wouldn’t have to drag water and fuel out of Earth’s gravity well every time they went into space, saving enormous amounts of fuel and therefore dollars, said Spudis, a member of the science team for the Pentagon space probe Clementine, which discovered the possible evidence of ice during its 1994 moon fly-by.

Planetary researchers are thrilled by the prospect, because water is an essential ingredient of any human outpost in space and because the possible ice may well harbor clues to Earth’s own origins 4.5 billion years ago. “If people are going to be involved in space, it’s almost inevitable that we’ll use the moon as a springboard,” said Brown University geophysicist Carle Pieters.

But scientists cautioned that the evidence is far from conclusive. “It’s a noisy signal. It’s a weak signal,” said MIT geophysicist Maria Zuber. “It’s like the Mars rock findings. It isn’t proven, but it’s sufficiently robust to be published.”

The signs that as much as four football fields worth of dirty ice may be hidden in the moon’s shadows were detected from Clementine, which was designed to test navigation skills for the Star Wars missile defense program. The 500-pound spacecraft took the images as an afterthought, bouncing radar beams off deep craters at the moon’s south pole and back to receivers on Earth.

Researchers have been analyzing the data from that single fly-by since spring 1994, but only now are they sure enough of their findings to announce them publicly.

The results--along with the recently announced evidence that life may have existed on Mars--come at a fortuitous time for the nation’s space agency, whose budget has been cut by hundreds of millions of dollars over the past several years. NASA chief Daniel Goldin was exuberant: “Every time we turn around, there’s another new finding,” he said.

Goldin was adamant, however, that the moon findings were extremely tentative and, in any event, “we should not use any one of these discoveries as an excuse for throwing money at the space program.”

Instead, he saw the recent string of NASA’s successes as the payoff from the “investment we’ve made over the past five years in new tools and techniques.”

The idea that ice lakes might lurk in dark crevices of the moon goes at least as far back as the 1960s. “We proved [using mathematical models] that water molecules bouncing around could get trapped,” said Caltech geophysicist Bruce Murray, who coauthored the first paper.

But because the ice would only collect at the bottom of a dark hole, there would be no way to see it from Earth. The Apollo moon missions didn’t pass by the moon’s poles, but even if they had, Murray said, they couldn’t see a place that the sun never illuminates.

Clementine was already orbiting the moon when researchers got the idea to see if they could find ice in cold spots that never saw the sun. Using the craft’s transmitting antenna as a radar beam, they sent radio signals (low-energy light waves) into a crater that sits inside an already low-altitude basin. The reflected beams were detected by NASA ground telescopes in Arizona.

“It’s very difficult to make that measurement,” said Murray, who remembered that rumors about the finding were circulating among planetary scientists as long as two years ago. The fact that it took so long to get them out means that “the results weren’t obvious,” he said.

Still, if the finding proves correct, the discovery of a water source on the moon could give a tremendous lift to space exploration. Since the moon is practically next door, “it’s not that much harder to get to the moon than to Earth orbit,” Zuber said. Telescopes on the moon, for example, would rise high above the blurring effects of Earth’s atmosphere.

However, without water, the moon is “a horrible place to go,” Murray said. It’s blisteringly hot for two weeks of the month, then frigid cold for two more--requiring power for air-conditioning and heat. It’s bone-dry and has little to recommend it in terms of life-sustaining elements.

H2O provides two of the most important elements, however: hydrogen and oxygen. If the ice could be melted, future astronauts could drink it, and they could breathe the oxygen released. What’s more, the hydrogen and oxygen could be used as fuel to generate power. “You could even grow plants,” Murray said--if you brought along carbon, nitrogen and a few other things.

None of this, though, would happen any time soon. As Goldin pointed out, the possible ice sits at the bottom of a cold well hundreds of degrees below zero. “This is a dark hole. You need an energy source to warm it up to liquid, then to [break it apart] into hydrogen and oxygen.”

At present, there is no obvious way to bring a heater up to the moon that could melt that much ice, although, Goldin said, “we have ideas.”

Intriguingly, the dark, icy patches found by Clementine may sit close to a high area that gets nearly constant sunlight--a perfect place to put solar panels to soak up the sun’s power to melt ice.

Even those scientists skeptical about moon-based science were looking forward to a better view of the possible ice itself--because it could contain traces of the primordial cloud that condensed to form Earth.

Since the moon is completely dry, any existing ice must have been brought there by comets, researchers said. And comets are leftover chunks of the original material that made the solar system. “It might be really primordial ice,” said UC Berkeley geophysicist Raymond Jeanloz.

Since ice at very low temperatures is as hard as steel, Murray said, any traces of comet material trapped in the water would be permanently frozen and preserved.

NASA’s next mission to the moon--the Lunar Prospector--is due to pass over the same region late next year. And unlike Clementine, it will carry instruments specifically designed to detect the presence of ice.

Nevertheless, the $75-million Clementine managed to take 1.8 million images of the moon during its serendipitous visit. Goldin and others thinks that its success bodes well for the future of fast, cheap space science.

“This was a low-budget enterprise,” said Dwight Duston of the Ballistic Missile Defense Organization. “So we decided to use a target that Mother Nature had put up for us. That was the moon.”

Times staff writer Art Pine in Washington contributed to this story.

Further information about the moon finding may be found at the following Internet sites:

https://www.nrl.navy.mil/clementine/

clementine.html;

https://www.sciencemag.org/

science/scripts/display/full/ 274/5292/1495.html;

and https://clementine.cnes.fr/

index.en.html

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Moon Ice?

1) A small spacecraft named Clementine bounced radar off the moon’s south pole in 1994.

2) Scientists studying the data noticed that the radar signal was reflected at a higher than expected rate, leading them to speculate that it may have bounced off ice.

3) If the ice exists, is thought to be inside a huge crater straddling the lunar south pole. The crater and ice may have formed when a comet collided with the moon.

Scientists’ reaction:

Confident: “We think we have found ice....It’s possibly the most valuable piece of real estate in the solar system.”

--Paul Spudis, Lunar and Planetary Institute, Rice University, member of science team.

*

Not so confident: “The odds that they’ve found is actually water is less than 50 per cent; they only had one pass to do this....It gives you a place to target on the next mission.”

--Maria Zuber, geophysicist at Massachusetts Institute of Technology

Source: Science magazine

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Moon Ice? (Southland Edition, A19)

* A small spacecraft named Clementine bounced radar off the moon’s south pole in 1994. Scientists studying the data noticed that the radar signal was reflected at a higher than expected rate, leading them to speculate that it may have bounced off ice.

* If the ice exists, is thought to be inside a huge crater straddling the lunar south pole. The crater and ice may have formed when a comet collided with the moon, leaving a deep depression and remnants of the comet’s icy tail.

Scientists have theorized that the poles would be the likely places to find ancient ice, especially the south pole, because the high walls of the crater’s rim casts the interior in permanent shadow. Temperatures there are near minus 380 degrees Fahrenheit.

Confident: “We think we have found ice....It’s possibly the most valuable piece of real estate in the solar system.”

--Paul Spudis, Lunar and Planetary Institute, Rice University, member of science team.

*

Not so confident: “The odds that they’ve found is actually water is less than 50 per cent; they only had one pass to do this....It gives you a place to target on the next mission.”

--Maria Zuber, geophysicist at Massachusetts Institute of Technology