Satellite to Track Shifts in Earth’s Surface

Compared to the dazzling weather, communications and spy satellites circling the Earth, the new moonlet awaiting launch aboard the shuttle Columbia is notably inelegant. It has no computer, no camera, no power supply, no communications gear.

It is nothing but a 900-pound ball, a brass core, surrounded by an aluminum shell covered with 426 reflectors.

But scientists are counting on the dimpled sphere resembling a huge golf ball to help them accurately record movement of the massive plates that underlie the planet’s surface. The shifting of the plates over millions of years is believed to have brought the continents to their present sites. Their continuing movement provides the geneses of earthquakes and volcanoes.

Designed to circle the planet for centuries, LAGEOS II--which stands for laser geodynamics satellite--will serve as a reflector for laser beams fired from stations spread around the Earth. With its position in space pinpointed within a fraction of an inch, scientists will be able to detect tectonic plate movements of a few inches a year. More than that, they will be able to discern subtle changes in the Earth’s gravitational field and even record the way that the planet’s crust rebounds after the withdrawal of glaciers.

Columbia astronauts, preparing for launch Thursday, are scheduled to deploy the Italian-built reflector as they cross the Indian Ocean on the second of 10 days in space. Forty-five minutes after it is lifted out of the cargo bay, the satellite will be boosted from the release altitude of 184 miles to 3,666 miles and maneuvered into a circular orbit that will take it for centuries over seismically active areas such as California and the Mediterranean basin.

The satellite will work in conjunction with an identical device, LAGEOS I, whose near-polar orbit since its 1976 launch has enabled scientists to identify movements over part of the Earth’s surface. The first LAGEOS has enabled scientists to see that the Hawaiian island of Maui is moving northwest toward Japan at the rate of about three inches a year, confirming a prediction of plate tectonics theory.

Because the paths of the two satellites intersect at almost a 90-degree angle, they will cover nearly all of the Earth’s surface. The two LAGEOS devices are among more than a dozen satellites used for laser-ranging measurements and are perhaps the most effective because they were designed for extraordinary stability in orbit.

LAGEOS I is losing altitude at the rate of a little more than one millimeter a day, meaning that it will continue on its present course for millions of years. LAGEOS II is expected to be similarly stable.

The satellite to be launched by Columbia was developed in a cooperative venture begun in the early 1980s with the Italian Space Agency.

Seeking a niche in the U.S. manned space flight program, Italian officials proposed developing a small interim stage rocket to transfer payloads from the shuttle to higher altitudes. U.S. officials identified a second LAGEOS as a potential payload and an agreement was struck for the Italians to provide the satellite as well. Such an agreement would not be possible today. In the wake of the Challenger shuttle disaster, regulations were approved that prohibit use of shuttles to launch payloads that could instead be carried into orbit by expendable rockets.

LAGEOS II does not require the shuttle as a launch vehicle but the project will go forward because the agreement predates the new regulations. LAGEOS I was put in orbit by a Delta rocket. If there is a LAGEOS III, it will be launched by an unmanned booster as well, officials said.

The delivery of LAGEOS II is only one of 25 major mission objectives for the Columbia crew on their upcoming flight.

Besides the reflector-covered satellite, Columbia will carry 11 other payloads when it lifts off on its 13th trip to orbit. Among them is a Canadian package outfitted with 10 varied experiments, including a space vision system designed to aid future astronauts in tasks such as space station construction.

And as have other shuttle crews, Columbia’s astronauts will conduct investigations seeking to determine why many astronauts experience back pain and motion sickness.

Besides Canadian payload specialist Steven MacLean, 37, all six members of Columbia’s crew have flown on previous shuttle operations. Mission commander James D. Weatherbee, 39, a U.S. Navy commander who has been an astronaut since 1984, will be making his second trip into orbit. Other crew members are Michael A. Baker, 38, a Navy captain and shuttle pilot, and mission specialists Charles L. Veach, 48, William M. Shepard, 43, and Tamara E. Jernigan, 33. Plans call for a landing at Kennedy Space Center after 159 orbits of the Earth.