Earth Looks Back to Moon for Exploration

SACRAMENTO, Calif. (December 6, 1997 01:35 a.m. EST http://www.nando.net) - Earth's most familiar celestial neighbor gets fresh scrutiny next year in the first space mission dedicated solely to the moon in 25 years.

A small spacecraft dubbed Lunar Prospector is scheduled to be launched on Jan. 5 from Florida. A spinning cylinder that looks like a drum, the satellite will circle the moon from pole to pole for a year or so, its instruments searching for frozen water and elements that could support a permanent human base.

The craft will be controlled by a Bay Area team based at the National Aeronautics and Space Administration's Ames Research Center at Moffett Field.

To those who would ask, "Don't we already know a lot about the moon?" the scientists say, "Not really."

The Apollo missions that put astronauts on the moon six times focused on a belt around the equator, the safest place for people should they require an emergency trip home, said G. Scott Hubbard, mission manager for Lunar Prospector.

"We know a great deal about that part of the moon, but we don't have the global picture," said Hubbard, who is deputy director of space at Ames. "We don't know for sure that those things are typical of the moon as a whole. It's like we have rocks from Texas and you assume from that that you know what the rest of the Earth is made of."

The most intriguing question that Lunar Prospector is meant to answer is whether the moon has water.

Common images of the moon show an arid surface, but a scientist as far back as 25 years ago postulated that a crater permanently in shadow would hold water ice. In 1994, scientists analyzing data from a U.S. Department of Defense lunar satellite called Clementine saw suggestions that ice left by passing comets might be contained at the south pole in a crater that never sees sun.

Scientists reading the shape and strength of radio waves beamed into a dark depression said the waves may have bounced off water ice. Other radio probes since then have produced conflicting information. Lunar Prospector's team hopes to settle the matter.

Hubbard said the craft will use a neutron spectrometer to take a direct reading. The tool will measure the movement of neutron masses present everywhere on the moon. Created by the continuous bombardment of cosmic rays on the moon's surface, neutrons travel quickly through dry material, and slowly through water.

If frozen water exists in the quantity some suspect, the neutron spectrometer should be able to detect it unambiguously, Hubbard said. "People say there could be a billion tons of ice."

If that's true, "people can have dreams about making a lunar base, manufacturing water and oxygen and so forth," Hubbard said.

While there are no solid plans for colonizing the moon, NASA's 1996 Strategic Plan includes this goal: "Explore and settle the solar system. ... Enrich life on Earth through people living and working in space."

Michael J. Drake, director of the University of Arizona's Lunar and Planetary Laboratory, called the moon a natural base.

"While Mars is a very exciting place, and ultimately the place, that people will want to go and live, we will want to go to the moon first. It's only five days away."

Besides looking for water, Lunar Prospector will watch for volcanic eruptions and quakes; record the moon's fields of gravity and patches of magnetism; and identify and measure geologic elements. The information will allow scientists to draw maps of the moon in unprecedented detail, and give them clues to the origins of the moon and Earth.

It's not that the moon has been ignored since the heady days of moonwalks in the late 1960s and early '70s. There was the Clementine mission in 1994 - which had a primary goal of testing Star Wars technology - and four years before that, a flyby by the spacecraft Galileo, on its way to Jupiter.

The appeal of a new moon mission was in large part a desire to demonstrate NASA's new motto, "Faster, Cheaper, Better."

Costing $63 million, Lunar Prospector was the first of the so-called Discovery-class missions chosen in competition against other proposals for trips to space priced at $200 million or less.

Showing that worthy space exploration can be done without breaking the treasury is, in fact, the prime goal of Alan Binder, Lunar Prospector's chief scientist.

"I believe the demonstration of this small, simple project is the main point," said Binder, a planetary scientist affiliated with Lockheed Martin in Sunnyvale, maker of the launch vehicle. "Clearly, I have to get good scientific data to prove the point."

Ultimately, Binder would like to see lunar exploration done commercially. He recently founded the Lunar Research Institute, based for the moment in his Gilroy home, toward that goal.

But first, Lunar Prospector must fly successfully. Binder said going low-budget means forgoing some measure of reliability. Normally, he said, NASA demands 99 percent reliability. For Discovery missions, the standard is 95 percent - meaning one out of 20 can be expected to fail.

Binder said the launch vehicle is the main potential weak point, because it is relatively untested and employs new software.

To keep the mission cheap, he said, only one version of the spacecraft was built, with no backups of anything. Prospector is made with technology that has been used before, though in different configurations.

Powered by batteries recharged by the sun, the craft is so simple that it won't even carry a computer on board. A "command-data handling unit" will take directions from Mission Control, one command at a time.

By EDIE LAU, the Sacramento Bee