[meteorite-list] Astronomers Survey Sky For Big Asteroids

From: E.P. Grondine <epgrondine_at_meteoritecentral.com>
Date: Thu Apr 22 09:55:47 2004
Message-ID: <20020115085537.37987.qmail_at_web11606.mail.yahoo.com>

Somebody needs to tell Clark Chapman that an asteroid
or comet impacted at Rio Cuarto, and that this was
just one of a number of fatal impacts which occured
within recorded human history. My old list of fatal
impacts may be found in the meteorite list archives,
and some additions to this list may be found here:

http://abob.libs.uga.edu/bobk/ccc/ce010702.html

EP

--- Ron Baalke <baalke_at_zagami.jpl.nasa.gov> wrote:
>
>
>
http://www.floridatoday.com/!NEWSROOM/localstoryA8730A.htm
>
> Astronomers survey sky for big asteroids
>
> Researchers try to increase alert time for such
> objects
>
> By Steven Siceloff
> FLORIDA TODAY
> January 13, 2002
>
> CAPE CANAVERAL -- The odds of dying from an asteroid
> impact are better than
> winning the lottery, researchers said, but the
> nation puts little effort
> into preparing for the possibility.
>
> The search for asteroids is critical if humans are
> to get a chance to rescue
> themselves, officials said. That's why Congress
> ordered NASA to identify
> almost all the objects two-thirds of a mile or
> larger by 2008. So far, more
> than 300 have been identified as possible threats to
> Earth.
>
> "We're running as fast as we can with the technology
> we have," said
> astronomer Stephen Pravdo, project manager for the
> Near Earth Asteroid
> Tracking project.
>
> But by allocating only a few million dollars a year
> to an effort that must
> identify 90 percent of the objects over six years,
> Congress is playing the
> odds, betting scientists will win.
>
> They face a daunting task. The hazard was
> highlighted Jan. 7, when a
> 300-yard-long rock missed Earth by 520,000 miles.
> The asteroid, named YB5,
> would have destroyed an area the size of France had
> it hit this planet.
>
> Researchers had almost no warning, and spotted it
> only two weeks before its
> closest approach.
>
> Increasing the alert time for such objects is the
> sole goal for the fewer
> than 100 astronomers who have turned their attention
> to so-called near-Earth
> objects. They hope to give earthlings enough time to
> divert an asteroid in
> case one is found headed this way, even though the
> chances are slim there
> will be a major impact during their lifetimes.
>
> "I don't think there is a right answer for how
> seriously to take it," said
> Clark Chapman, an asteroid impact specialist at the
> Southwest Research
> Institute in Boulder, Colo. "A big asteroid hasn't
> hit in recorded human
> history, but it could happen next year. The chances
> are the same as dying in
> an airplane crash, with or without terrorists."
>
> Congress authorized as much as $7 million a year for
> a survey of the solar
> system near Earth that hopes to find 90 percent of
> all the objects larger
> than two-thirds of a mile, but only half of that is
> ever allocated, David
> Morrison said. He heads NASA's asteroid and comet
> impact research effort at
> Ames Research Center in California.
>
> The money has provided technological leaps for
> asteroid astronomers.
>
> Working each year with slightly more than 1/10th the
> cost of the Odyssey
> robotic mission to Mars, astronomers have developed
> computers that turn
> telescopes into celestial sentries.
>
> "Up to the early 1990s, it was a couple (asteroids
> found) per year," Pravdo
> said. "Now it's hundreds per year, sometimes 30 a
> month."
>
> So far this month, the team has found four new
> objects, one of which passes
> close enough to Earth to be considered dangerous,
> though it is not expected
> to hit the planet. Researchers have spotted 1,739
> near-Earth objects, the
> majority since 1997. More than 500 of them are
> larger than two-thirds of a
> mile, with 367 classified as potential threats.
>
> Don Yeomans, manager of NASA's Near Earth Objects
> program, estimated there
> are about 1,000 asteroids in the solar system larger
> than two-thirds of a
> mile. There could be 100,000 rocks big enough to
> chew up a state if they hit
> Earth.
>
> When Pravdo and astronomers around the world find a
> new object, other
> astronomers use special devices and radar telescopes
> to determine what it is
> made of and calculate the exact path it will take.
>
> The objects of most concern are the relatively large
> rocks that could
> explode over a city and asteroids almost a mile wide
> that could spell a new
> extinction. Earth's atmosphere absorbs the impact of
> countless small objects
> daily.
>
> There are few signs of past meetings with asteroids.
> One of the most famous
> is a mile-wide crater in Arizona. A 100-foot meteor
> traveling 40,000 mph is
> thought to have excavated the desert 50,000 years
> ago.
>
> Mexico's Yucatan Peninsula is thought to be part of
> the crater left by a
> massive boulder from space that eliminated the
> dinosaurs 65 million years
> ago.
>
> "We're dealing with this hazard that is very
> unlikely to happen, but if it
> does happen, it will be the biggest event to happen
> to humanity since we
> emerged from the caves," Chapman said.
>
> Morrison puts the odds of dying from an asteroid
> impact at 1 in 20,000
> during a typical lifetime -- the same as dying in a
> plane crash.
>
> The only way to know with relative certainty is to
> look for the objects and
> figure out where they are going.
>
> "The issue is not statistics, but when the next hit
> will take place,"
> Morrison said. "That is why Spaceguard is finding
> and tracking real objects,
> not trying to improve the statistics."
>
> Many in the space community argue for more funding
> to quicken the pace of
> discovery, and then work on finding smaller but
> lethal objects.
>
> "If we could get the budget up to $10 million a
> year, we could accomplish
> what we need to accomplish," said Marc Schlather,
> director of the
> Washington, D.C.-based ProSpace grass-roots
> organization.
>
> Morrison said the Earth needs 10 to 20 years warning
> to deal with an
> incoming object. That is possible with a thorough
> survey of the heavens. The
> country needs the time to develop rockets,
> spacecraft and plans to divert
> the asteroid.
>
> Bob Farquhar, who led the NEAR mission that landed
> on the asteroid Eros last
> year, said the space program should develop a small
> shuttle craft that can
> travel from space station Alpha to deep space on
> short order. With that
> capacity, a crew could intercept a killer asteroid
> years before it has a
> chance to threaten the planet.
>
> Shuttle astronauts could attach a small rocket motor
> that gradually would
> push the object's orbit away from Earth. The
> Hollywood solution -- nuclear
> warheads shot at or detonated inside an asteroid --
> would not likely solve
> the problem, most agree
>
> "That might break it up into smaller pieces, and I'm
> not sure if that's good
> or bad," Farqua said.
>
> For now, Farqua said it is important the country
> understand there is a
> danger that can be averted, but the risk is small
> during this lifetime.
>
> "The rate they're going, the politicians are still
> not taking this threat
> very seriously," he said. "I don't know what it's
> going to take, maybe a
> small one hitting us first."
>
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Received on Tue 15 Jan 2002 03:55:37 AM PST