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Satellites Brace for Space Storm

November 14, 1998

WASHINGTON (AP) _ The most intense meteor shower in 33 years is threatening to sandblast America’s multi-billion dollar satellite fleet, including military spacecraft that provide vital support for the U.S. military deployment in the Persian Gulf.

On Tuesday, the Earth will pass through the Leonid meteor storm, a cloud originating from the dusty passage earlier this year of comet Tempel-Tuttle.

A blizzard of meteor particles, some the size of sand, but mostly smaller, will rain down on the planet for about 10 hours. The most intense part of the storm peaking at about 2:45 p.m. EST.

There’s no threat to people because the space particles burn up in the atmosphere before reaching the ground. In fact, in Asia and the western Pacific, where it will be nighttime, the storm will create a spectacular celestial show of light streaks and ``shooting stars.″

But in the vacuum of space, where the nation’s satellite fleet orbits the earth, particles from the Leonid meteor storm will flash past vulnerable spacecraft at more than 155,000 miles an hour. At that speed, a small grain can have the destructive force of a .22-caliber bullet.

The most likely damage could be electrical. The high speed impact of a tiny meteor creates a sudden electrical discharge that can cause the satellite to short out. If the electrical charge is big enough, it could permanently disable the craft.

Actual collisions are expected to be rare, but operators of some 300 U.S. military, commercial and scientific satellites are crossing their fingers.

``We rate the possibility of anything catastrophic as being minimal, but we can’t rule it out,″ said Air Force Maj. Perry L. Nouis of the U.S. Space Command at Peterson Air Force Base, Colo., the mission control center for the nation’s 150 or so military satellites.

He said military experts estimated that one or two of the world’s 600-plus satellites will be destroyed by a meteor during the Leonid storm.

Nouis said that all the U.S. military satellites will continue to operate through the meteor storm. The satellites facilitate communication, navigation, surveillance and missile warning worldwide.

With American forces in the Persian Gulf poised to attack Iraq, there is a heavy demand for the satellite services, but Nouis said ``we are prepared to carry out our mission″ through the Leonid storm. Even if a single craft is lost, he said, there are back-up spacecraft for each system.

Among the satellites most at risk are communications satellites, typically stationed at 22,300 miles above the Earth, and the Global Positioning Satellites which are 11,000 miles out.

``Those satellites pretty much have to fend for themselves,″ said Nouis. ``The defensive measures have to have been built into the systems.″

Most U.S. military satellites have been ``hardened,″ shielded against the effects of nuclear radiation. They are expected to withstand all but the most unlucky hits by the speeding meteors.

The 22 satellites controlled by NASA, however, are more vulnerable.

``We are taking some precautions with all of them,″ said Phil Liebrecht, chief of the satellite control office at the Goddard Spaceflight Center.

Six $500 million Tracking and Data Relay System satellites will alter their position so they present the smallest possible target to the speeding meteor dust.

Liebrecht said other satellites will rotate solar power panels so that they face the storm edge-on.

And other spacecraft will be powered down for at least part of the 10-hour passage through the Leonids.

Liebrecht said NASA is most concerned about two satellites that are stationed one million miles from the Earth toward the sun. Both craft are designed to study the sun and were placed where they get the best view. Now they will be in the most intense part of the Leonid meteor storm, he said.

``It looks like there is about a one percent chance that they will get hit and have something go wrong,″ said Liebrecht.

All high voltage instruments on the two craft will be shutdown to minimize the risk of an electrical short. Solar arrays will be rotated to a protective attitude.

For NASA craft in lower orbits, such as the Hubble Space Telescope, the odds of damage from a meteor impact are calculated at about one in 10,000, Liebrecht said.

Even so, the Hubble, filled with delicate optics, will be turned so that its back is toward the Leonids.

Meteor showers from the dusty wake of comets are fairly common. In fact, the Earth annually crosses the path of Comet Tempel-Tuttle and encounters the Leonids.

What makes this year exceptional is that Tempel-Tuttle sped passed the Earth’s orbit last February, leaving behind a fresh wake of dust and gas. This only happens every 33 years.

Liebrecht said that the last time Tempel-Tuttle went by, in 1966, it left an even denser path of debris, setting off a spectacular show of shooting stars.

At the time, though, the space age was in its infancy and only a handful of satellites orbited the Earth.

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