[meteorite-list] Big New Asteroid Has Slim Chance of Hitting Earth (2006 HZ51)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed May 3 18:54:44 2006
Message-ID: <200605031538.IAA09939_at_zagami.jpl.nasa.gov>

http://www.newscientistspace.com/article/dn9095-big-new-asteroid-has-slim-chance-of-hitting-earth.html

Big new asteroid has slim chance of hitting Earth
David Chandler
New Scientist
02 May 2006

A newly discovered asteroid is now the biggest thing known with a
possibility of hitting the Earth in this century - and it is also the
one that could hit the soonest.

But the odds of impact currently stand at just one in six million,
reducing the fear factor somewhat, and these odds should further
diminish with additional observations. This latest addition to
NASA-JPL's list of potentially hazardous asteroids was discovered on 27
April 2006.

The asteroid, called 2006 HZ51, has an estimated diameter of about 800
metres and is the one of the largest objects ever to make the list. An
object of that size would cause widespread devastation if it did strike
the Earth.

HZ51 also has one of the shortest lead-times to a potential impact of
any such object yet found, and the shortest of any potential
Earth-impactor currently on the list. The earliest of its 165 possible
impact dates is just over two years away, on 21 June 2008.

Hollywood movies

Dan Durda, an asteroid expert and president of the B612 Foundation -
which aims to anticipate and prevent such impacts - thinks the discovery
of HZ51 highlights that at present there are no good options when faced
with so little time to prepare. "There really isn't a whole lot we could
do," he told New Scientist. "Most of the options that don't resemble a
Hollywood movie involve deflection techniques that require many years or
decades."

Other than stockpiling food and supplies and evacuating the regions most
likely to be affected, he said, we would have to "hunker down and take
the impact".

But this is an unusual case, statistically speaking. It is far more
likely that Earth's nations would benefit from a much greater lead time
before a potential impact, allowing more time for planning.

For example, the second-most imminent threat now on the list is the
asteroid Apophis, which has about a 1-in-6000 chance of hitting Earth in
2036 - plenty of time to prevent it.

Altering orbits

The B612 Foundation has been pushing for a mission to place a tracking
device on Apophis sometime in the next decade, so that the possibility
of impact can be definitively proved or ruled out. The foundation also
wants to send a mission to test ways of altering the orbit of a
non-threatening asteroid, to test the viability of such methods.

But the chance of an impact by Apophis might be ruled out as early as
this weekend, which will be the last chance until 2013 to observe it by
radar, from the Arecibo radio telescope in Puerto Rico.

As for the newfound 2006 HZ51, the orbit calculations so far are based
on just over 24 hours of observations, and so are likely to change
quickly and should not be seen as a serious concern. As Clark Chapman of
the Southwest Research Institute in Boulder, Colorado, US, explains:
"Almost certainly, observations from one or two more nights will put
this to bed as a zero probability."
Received on Wed 03 May 2006 11:38:27 AM PDT