| Topic: |
Religions > Atheism |
| User: |
"Enkidu the Atheist" |
| Date: |
15 Nov 2005 06:17:15 AM |
| Object: |
OT:2 astronauts devise asteroid collision plan |
2 astronauts devise asteroid collision plan
'Tractor beam' could push rogue rock off its path to Earth
Guy Gugliotta, Washington Post
Monday, November 14, 2005
Two NASA astronauts have figured out a way to create a real-life version
of a Star Wars "tractor beam" to keep an asteroid from crashing into the
Earth.
Simply by hovering nearby for perhaps a year, the astronauts say, the
spacecraft's own gravity could minutely slow the asteroid's progress or
speed it up, a process that 10 or 20 years later would cause the rogue
rock to miss Earth by a comfortable margin.
"The beauty of this idea is that it's incredibly simple," astrophysicist-
astronaut Edward Lu said. Because momentum doesn't dissipate in space,
with enough time only a small early nudge is needed to cause a major
orbital change.
Lu, who has made three trips to space, including a six-month stint aboard
the international space station, and fellow astronaut Stanley Love, who
has not yet flown, describe the design of their "gravitational tractor"
last week in the journal Nature.
The two are in the middle of a spirited debate among space buffs,
astronomers and space agencies worldwide over what to do about "near
Earth objects" -- comets and asteroids like the one that many scientists
say caused the catastrophic extinction that finished off the dinosaurs 65
million years ago.
This discussion, for years a sci-fi giggler among fans of movies like
"When Worlds Collide" and "Deep Impact," suddenly became serious late
last year when astronomers spotted an incoming asteroid whose probability
of hitting Earth on April 13, 2029, rose from 1 chance in 170 to 1 chance
in 38.
By year's end, it was clear that the 1,000-foot-wide space rock,
originally designated 2004 MN4 but now named 99942 Apophis, will miss --
but only by 22,600 miles. And if it gets exactly the right kind of
gravity boost from the 2029 encounter, it will smack into the Earth seven
years later with enough force to obliterate Texas or a couple of European
countries.
With this in mind, former astronaut Russell Schweickart wrote a letter in
June to NASA Administrator Michael Griffin, suggesting the agency send a
mission to plant a radio transponder on Apophis to better monitor its
orbit. Ruling out -- or ruling in -- a future impact requires the best
available orbital data.
Schweickart heads the B612 Foundation, an organization of experts who
advocate developing a spacecraft that can alter an asteroid's speed
enough to keep it from colliding with Earth. The foundation is named
after the asteroid home of "The Little Prince" in the Antoine de St.-
Exupery story.
Schweickart originally advocated a tugboat strategy to dock with an
asteroid and push it gently off its collision course, but he endorsed Lu
and Love's idea as "a delightful way to pull an asteroid instead of
pushing it -- we're all (in the foundation) sort of uncles to the tractor
beam."
Lu and Love's design would use a relatively small 20-ton spacecraft
powered by charged atomic particles called ions, generated by an onboard
nuclear reactor. Such a propulsion system would -- at relatively low
weight -- provide enough power to accelerate the probe to the speeds
needed to run down the target asteroid.
With ordinary chemical fuel, "you'd be talking about a spacecraft that's
20 to 40 times larger," Lu said at Houston's Johnson Space Center. "That
kind of technology doesn't exist."
Once on station, the spacecraft would hover above the asteroid, using its
engines to stay in place. Gravity is a two-way street, noted Love, also
speaking from Houston. Even as the spacecraft counters the asteroid's
gravity, he said, its own gravity will pull the asteroid out of orbit.
"The velocity increment is small -- fractions of a centimeter (hundredths
of an inch) per second," Lu added. "Suppose the asteroid is traveling
60,000 mph. You want to make it 60,001." This, Lu suggested, might take a
year or two years, but that would be enough, for the change would then
accumulate over a decade or more, sending the asteroid harmlessly away.
Bigger asteroids would simply take more time.
Unlike Schweickart's tug, the tractor would work even if the asteroid
rotates or tumbles, and unlike nuking the asteroid -- Bruce Willis'
solution in "Armageddon" -- the tractor is not messy.
"Impacts and explosions are difficult to predict and control," said Love.
"When you're trying to save the Earth, you want them to be both
controllable and predictable."
Unfortunately, Schweickart noted, research on nuclear powered space
vehicles has been cut dramatically to help fund President Bush's
initiative to send humans to the Moon and Mars. But fortunately, he
added, it appears that the Apophis threat can be handled with a
conventional spacecraft.
In an October reply to Schweickart's June letter, NASA Associate
Administrator for Science Mary Cleave outlined a potential response to
Apophis. The critical task, she said, is to ensure that the asteroid does
not pass through a 2,000-foot keyhole in space during its 2029 near-miss.
Schweickart explained that the Earth's gravity at close quarters will
slingshot Apophis into a wider orbit, putting it in "resonance" with
Earth -- the two bodies will meet up every sixth Apophis orbit and every
seventh Earth orbit. If Apophis hits the keyhole in 2029, the result will
be impact in 2036.
Cleave noted, however, that by analyzing Apophis's orbit during detailed
observations next year and in 2013, scientists will have a much better
idea of the asteroid's 2029 trajectory. If the threat still exists, a
simple interception mission -- with chemical propellant -- would send a
spacecraft in the early 2020s to smack into the asteroid like a celestial
shotgun shell, changing its velocity by a few thousandths of an inch per
second -- much more than enough to move it 2,000 feet by 2029.
--
Enkidu AA#2165
EAC Chaplain and ordained minister,
ULC, Modesto, CA
PGP ID: 0xC4CE8CF0
As a set of cognitive beliefs, religion is a speculative hypothesis of an
extremely low order of probability.
-- Sidney Hook, The Partisan Review, March 1950
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| User: "Denis Loubet" |
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| Title: Re: OT:2 astronauts devise asteroid collision plan |
15 Nov 2005 10:13:06 PM |
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"Enkidu the Atheist" <enkidu@leaddogs.org> wrote in message
news:Xns970EE2BE55366255229@130.133.1.4...
2 astronauts devise asteroid collision plan
'Tractor beam' could push rogue rock off its path to Earth
At first I thought the plan made no sense, since pushing or pulling, the
fuel requirements are the same. But the benefit comes if the asteroid is
tumbling, the gravity scheme means you don't have to waste energy
controlling the tumble.
Cool plan.
--
Denis Loubet
dloubet@io.com
http://www.io.com/~dloubet
http://www.ashenempires.com
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| User: "Harry F. Leopold" |
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| Title: Re: OT:2 astronauts devise asteroid collision plan |
15 Nov 2005 11:07:42 PM |
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On Tue, 15 Nov 2005 16:13:06 -0600, Denis Loubet wrote
(in article <7MydnRGibLvzwOfenZ2dnUVZ_tGdnZ2d@io.com>):
"Enkidu the Atheist" <enkidu@leaddogs.org> wrote in message
news:Xns970EE2BE55366255229@130.133.1.4...
2 astronauts devise asteroid collision plan
'Tractor beam' could push rogue rock off its path to Earth
At first I thought the plan made no sense, since pushing or pulling, the
fuel requirements are the same. But the benefit comes if the asteroid is
tumbling, the gravity scheme means you don't have to waste energy
controlling the tumble.
Cool plan.
As well it would allow them to handle asteroids (and comets) that are made up
of loose piles of rubble.
--
Harry F. Leopold
aa #2076
AA/Vet #4
The Prints of Darkness
(remove gene to email)
"But it could also be a new troll being born. (Do they form by accretion?)"
-Chuck Taylor
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| User: "Denis Loubet" |
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| Title: Re: OT:2 astronauts devise asteroid collision plan |
16 Nov 2005 02:23:52 AM |
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"Harry F. Leopold" <hleopold@coxyx.net> wrote in message
news:0001HW.BF9FC65E00342267F0284550@news.central.cox.net...
On Tue, 15 Nov 2005 16:13:06 -0600, Denis Loubet wrote
(in article <7MydnRGibLvzwOfenZ2dnUVZ_tGdnZ2d@io.com>):
"Enkidu the Atheist" <enkidu@leaddogs.org> wrote in message
news:Xns970EE2BE55366255229@130.133.1.4...
2 astronauts devise asteroid collision plan
'Tractor beam' could push rogue rock off its path to Earth
At first I thought the plan made no sense, since pushing or pulling, the
fuel requirements are the same. But the benefit comes if the asteroid is
tumbling, the gravity scheme means you don't have to waste energy
controlling the tumble.
Cool plan.
As well it would allow them to handle asteroids (and comets) that are made
up
of loose piles of rubble.
That too! :-)
--
Denis Loubet
dloubet@io.com
http://www.io.com/~dloubet
http://www.ashenempires.com
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| User: "Jim07D5" |
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| Title: Re: OT:2 astronauts devise asteroid collision plan |
15 Nov 2005 09:35:47 AM |
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Enkidu the Atheist <enkidu@leaddogs.org> said:
2 astronauts devise asteroid collision plan
'Tractor beam' could push rogue rock off its path to Earth
Guy Gugliotta, Washington Post
Monday, November 14, 2005
Two NASA astronauts have figured out a way to create a real-life version
of a Star Wars "tractor beam" to keep an asteroid from crashing into the
Earth.
<...>
Depiction:
http://antwrp.gsfc.nasa.gov/apod/ap051110.html
--- Jim07D5
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