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IP: Heavy Leonid meteor shower threatens communications




From: [email protected]
Subject: IP: Heavy Leonid meteor shower threatens communications
Date: Tue, 06 Oct 1998 06:11:35 -0500
To: [email protected]

Source:  San Francisco Examiner
http://www.examiner.com/981004/1004meteor.shtml

Heavy Leonid meteor shower threatens communications

Annual light show biggest in 32 years

By Keay Davidson
EXAMINER SCIENCE WRITER

A spectacular meteor storm will ignite the heavens in mid-November,
possibly "sandblasting" satellites and threatening everyday services from
cell phones to TV shows to data communications.

The last great meteor barrage came in 1966, when space satellites were far
less common - and far less essential to everyday life. Back then, thousands
of meteors per minute shot across the North American sky.

Today, the skies are jammed with satellites that aid in weather
forecasting, relay data communications and TV signals, and enable military
surveillance.

The world's satellite network is a juicy target for the blistering
celestial rain.

Although the meteors are smaller than grains of sand, they travel
tremendously fast - more than 40 miles per second, equivalent to a
10-second flight from San Francisco to Los Angeles. As a result, they could
knock out or disrupt some satellites' delicate electronics.

"This meteoroid storm will be the largest such threat ever experienced by
our critical orbiting satellite constellations," William H. Ailor, director
of the Center for Orbital and Reentry Debris Studies at the Aerospace Corp.
in El Segundo, Los Angeles County, told the House Science Committee on May 21.

The 1966 storm appeared over continental North America, but this year's
main aerial assault will be visible from Japan, China, the Philippines and
other parts of east Asia, and possibly Hawaii. The meteors are debris from
a comet, Tempel-Tuttle.

Scientists from NASA's Ames Research Center in Mountain View hope to study
the shower from aircraft flying out of Okinawa, says Ames principal
investigator Peter Jenniskens. They hope to broadcast live TV images of the
shower over the World Wide Web.

The "Leonid" meteor shower is so named because the meteors appear to
emanate from the direction of the constellation Leo. Actually, the shower
is a cloud of rocky particles orbiting the sun. 

Annual event

Earth crosses the cloud's path every Nov. 17 and 18. At that time, amateur
astronomers enjoy seeing the "Leonids" zip across the sky, sometimes
several per minute.

But every 30-plus years, our planet crosses a particularly dense part of
the Leonid cloud. So the "shower" becomes a "storm," with up to 40 meteors
per second and sometimes 50,000 per hour.

Although very tiny, the particles move so fast that the friction with
Earth's atmosphere will cause them to burn and glow. Visible from hundreds
of miles away, they will make the sky look like fireworks.

NASA plans to turn the Hubble Space Telescope away from the storm so
meteors that hit the giant orbital telescope will miss its super-delicate
mirror, says NASA spokesman Don Savage.

"NASA is taking (the shower) seriously," Savage said. "We have been
assessing what we need to do to ensure our satellites in Earth orbit are
going to be operated in a safe manner during this meteor shower."

Other satellites might be temporarily re-oriented so that they present the
narrowest "cross section" - the smallest target.

"We are concerned, and we have been in meetings and making plans concerning
the Leonid shower," said U.S. Army Maj. Mike Birmingham, a spokesman for
the U.S. Space Command in Colorado, which monitors
American military and spy satellites.

In his congressional testimony, Ailor said that "because of the very high
speed of the particles - they will be moving at speeds of over... 155,000
mph - the storm poses an even greater and somewhat unknown threat."

Most particles tiny

"Fortunately, most of the particles... are very small, smaller than the
diameter of a human hair, and won't survive passage through the Earth's
atmosphere," Ailor said. "Our satellites, however, are (in space and) not
protected by the atmosphere, so they will be 'sandblasted' by very small
particles traveling more than 100 times faster than a bullet. 

"At these speeds, even a tiny particle can cause damage or electrical
problems," Ailor said. "While major holes and physical damage to solar
panels and structures are very unlikely, impacts of small particles will
create an electrically charged plasma which can induce electrical shorts
and failures in sensitive electronic components."

Last month, an immense wave of radiation from a neutron star washed over
Earth, causing at least two scientific satellites to shut down to protect
their electronics.

Astronomers said the star, in a constellation about 20,000 light-years
away, had unleashed enough energy to power civilization for a
billion-billion years. But by the time the radiation found its way across
the cosmos and through the atmosphere, it was no stronger than a typical
dental X-ray, scientists said.

No conflict with space missions

The upcoming meteor shower is not expected to conflict with scheduled space
missions.

The first components of the international space station - a kind of village
in space - aren't planned for launch until late November and December,
after the shower, Savage said.

U.S. Sen. John Glenn, an Ohio Democrat and former astronaut, is scheduled
to rocket into orbit on the space shuttle Oct. 29, returning before the
Leonid shower.

Armed with sensitive monitors, Jenniskens' colleagues will study the
meteors' "spectra" - frequencies of light that reveal the particles'
chemical composition - through portholes in the roof of a plane. Scientists
will also
study the particles' effects on atmospheric chemistry, such as the ozone
layer that shields us from cancer-causing solar radiation.

The scientists hope to measure the particle stream, which may be as dense
as one extremely small particle every 10 square meters. If so, then every
satellite in the sky may get hit, Jenniskens say.

Jenniskens' project - involving some 30 scientists and two aircraft - is
funded by NASA, the U.S. Air Force and the National Center for Atmospheric
Research in Boulder, Colo.

He hopes to transmit high-resolution TV images of the incoming meteors via
TV or the Web across a 30-degree field of sky.

More information on the project is available on the Internet at
www-space.arc.nasa.gov/~leonid/.
-----------------------
NOTE: In accordance with Title 17 U.S.C. section 107, this material is
distributed without profit or payment to those who have expressed a prior
interest in receiving this information for non-profit research and
educational purposes only. For more information go to:
http://www.law.cornell.edu/uscode/17/107.shtml
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