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Re: (meteorobs) Re: Leonids meteor shower
To Lew, Ron and Luigi,
I did not read a news release but an article on ABC New Com Science on
the WWW
http://www.abcnews.com/sections/science/DailyNews/satellites980427.html
I just posted the headline for the list comment. I profess no specific
knowledge on the subject nor do I say I have sufficient knowledge of
this or any meteor showers I defer to you experts Lew and Ron for the
valid interpretation of the science of the news articles. I am just a
lay person interested in knowing the truth of the matter.
When Lew writes "And one final point, Victor: you did not read the news
releases closely enough (or with sufficient knowledge)..."
I plead guilty. I do not have sufficient knowledge. Please inform me
and the list.
The following is the complete article please address your critical
analysis for the author and the astronomers mentioned in the artilce.
Please.
The ABC News Article:
The particles, known as meteoroids, are vastly smaller than the
asteroids that could one day slam into Earth, and none are expected to
come anywhere near the surface of the planet when they strike this
November and again in November 1999.
Astronomers predict the Leonid meteor shower, which comes about every 30
years, will create a spectacular display over China in November 1998,
and could threaten the safety of spacecraft. (Reuters)
By Jane E. Allen
The Associated Press
M A N H A T T A N B E A C H, Calif., April 27 In November, the
Earth's atmosphere will be hit with the most severe meteor shower in 33
years, a bombardment of debris that could damage or destroy some of the
nearly 500 satellites that provide worldwide communications, navigation
and weather-watching.
The debris consists only of particlessome thinner than a hair and
most no larger than a grain of sandbut they are hurtling through space
so fast that they can have the destructive power of a .22-caliber
bullet.
As a result, about 200 commercial and military satellite operators,
insurers and scientists began brainstorming here today about what they
can do to prepare, such as turn off spacecraft or turn them away from
the stream of particles. The two-day gathering is called the Leonid
Meteoroid Storm and Satellite Threat Conference.
"The consequences are still virtually unknown. There has not been a
meteor storm since the onset of the modern space age. Nobody planned for
it," said Peter Brown, a physics and astronomy graduate student at the
University of Western Ontario who advises satellite operators.
The particles, known as meteoroids, are vastly smaller than the
asteroids that could one day slam into Earth, and none are expected to
come anywhere near the surface of the planet when they strike this
November and again in November 1999.
But before the particles burn up in Earth's atmosphere, they could
poke holes in solar panels, pit lenses, blast reflective coating off
mirrors, short out electronics with a burst of electromagnetic energy,
even reprogram computers, said Edward Tagliaferri, a consultant to the
Aerospace Corp., a nonprofit organization.
In 1993, for example, a meteor struck the European Space Agency's
Olympus satellite and destroyed its directional control, rendering it
useless.
"What if you get unlucky?" Delbert Smith, a Washington lawyer who
represents international networks and satellite operators, asked at the
conference. "Who's going to explain to the major corporations your
satellites aren't there anymore?"
Damage Will Be Widespread
While only a couple of satellites might get disabledand some cost as
much as $500 millionall of them will suffer surface damage, said David
Lynch, a scientist with the Aerospace Corp.
Military satellites are better shielded because most are built to
withstand nuclear assault. But unlike commercial spacecraft that can be
turned off temporarily, military satellites "can't afford to be off the
air," Tagliaferri said. The Hubble Space Telescopewhich suffered minor
surface damage in the 1993 showerwill move to protect itself against
Leonid damage by turning away from the stream of particles, an option
being considered by many satellite owners.
First reported by Chinese astronomers back in 902, the Leonid
meteoroid stormsso-named because they are found in front of the
constellation Leobecome intense every 33 years. They occur when Earth
passes through a trail of dust left behind by the comet Tempel-Tuttle.
Scientists aren't sure when the heaviest showers will occurNov.
17, 1998, or Nov. 18, 1999.
The spectacular showers will be visible this year across the
Western Pacific and Eastern Asia; the 1999 showers will be visible in
the Middle East, Eastern Europe and Central Asia. Storms last 90 minutes
to two hours.
Back in 1966, when fewer than 100 satellites circled the Earth, the
comet produced peak showers of 144,000 meteors each hour and no major
damage. This year, with more than five times the number of circling
spacecraft, some experts think the rate could be 5,000 to 100,000 an
hour.
But astronomer Donald Yeomans of NASA's Jet Propulsion Laboratory
in Pasadena put the rate as low as 500 to 2,000 particles per hour. And
Brown agreed that the rate won't be as high as it was in 196
>From majordomo@latrade.com Wed May 6 05:35:10 1998
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>Message-Id: <355057D7.2781@fisbat.bo.cnrdot it>
>Date: Wed, 06 May 1998 14:30:15 +0200
>From: Luigi Foschini <L.Foschini@fisbat.bo.cnrdot it>
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>To: meteorobs@latrade.com
>Subject: Re: (meteorobs) Re: Leonids meteor shower
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>Lew Gramer wrote:
>
>> And one final point, Victor: you did not read the news releases
closely enough
>> (or with sufficient knowledge)... The danger to artificial satellites
from any
>> putative Leonid storm is NOT due to a "bombardment of debris":
rather, it is
>> due to the possibility of extremely high levels of ionized particles
in the
>> Earth's upper atmosphere that might occur during a storm.
>
>I would like to point out that the damages from a meteoroid impact are
>of several types, such as the pure mechanical damage, the plasma
>production, and electromagnetic interferences. During last years
several
>authors underlined that the catastrophic impact is a rare event, but
>high meteoroids fluxes can weaken the satellite structures. Moreover,
>McDonnell et al. (University of Kent) showed that the plasma production
>is more dangerous than the pure mechanical impact. During a
>hypervelocity impact, the meteoroid and part of satellite material
>vaporize and plasma is produced. The free electric charge of the plasma
>can be injected into electronic circuits, making a short-circuit.
>
>If you are interested, I have written a review paper on this argument
>(with several related references) and you can freely download it from
>xxx Eprint server (http://xxx.lanldot gov/), that has mirrors all over the
>world. The preprint has number: physics/9804026, but you can also read
>the preprint physics/9804027.
>
>Greetings,
>
>Luigi Foschini
>
>
>--
>dr. Luigi Foschini
>CNR - FISBAT Institute
>Via Gobetti 101, I-40129 Bologna (Italy)
>tel. +39 51 639.9620/9622; fax +39 51 639.9654
>E-mail: L.Foschini@fisbat.bo.cnrdot it
>WWW: http://www.fisbat.bo.cnrdot it/homepp/dinamica/foschini.html
>
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