[meteorite-list] NASA Releases Workshop Data and Findings on Asteroid 2011 AG5

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 15 Jun 2012 10:24:41 -0700 (PDT)
Message-ID: <201206151724.q5FHOg01006546_at_zagami.jpl.nasa.gov>


Dwayne Brown
Headquarters, Washington June 15, 2012
dwayne.c.brown at nasa.gov

RELEASE: 12-189


WASHINGTON -- Researchers anticipate that asteroid 2011 AG5, discovered
in January 2011, will fly safely past and not impact Earth in 2040.

Current findings and analysis data were reported at a May 29 workshop at
NASA's Goddard Space Flight Center in Greenbelt, Md., attended by
scientists and engineers from around the world. Discussions focused on
observations of potentially hazardous asteroids (PHAs).

Observations to date indicate there is a slight chance that AG5 could
impact Earth in 2040. Attendees expressed confidence that in the next
four years, analysis of space and ground-based observations will show
the likelihood of 2011 AG5 missing Earth to be greater than 99 percent.

Measuring approximately 460 feet (140 meters) in size, the space rock
was discovered by the NASA-supported Catalina Sky Survey operated by the
University of Arizona in Tucson. Several observatories monitored 2011
AG5 for nine months before it moved too far away and grew too faint to see.

"While there is general consensus there is only a very small chance that
we could be dealing with a real impact scenario for this object, we will
still be watchful and ready to take further action if additional
observations indicate it is warranted," said Lindley Johnson, program
executive for the Near-Earth Object (NEO) Observation Program at NASA
Headquarters in Washington.

Several years ago another asteroid, named Apophis, was thought to pose a
similar impact threat in 2036. Additional observations taken from 2005
through 2008 enabled NASA scientists to refine their understanding of
the asteroid's path, which showed a significantly reduced likelihood of
a hazardous encounter.

"Any time we're able to observe an asteroid and obtain new location
data, we're able to refine our calculations of the asteroid's future
path," said Don Yeomans, manager of NASA's NEO Program Office at the Jet
Propulsion Laboratory (JPL) in Pasadena, Calif. "When few observations
exist, our initial orbit calculation will include a wider swath to
account for uncertainties. With more data points, the knowledge of the
potential positions of the asteroid improves and the swath becomes
smaller -- typically eliminating the risk of an impact."

Observations of 2011 AG5 have been limited to date because of its
present location beyond the orbit of Mars and in the daytime sky on the
other side of the sun. In fall 2013, conditions will improve to allow
space- and ground-based telescopes to better track the asteroid's path.
At that time, 2011 AG5 will be 91 million miles (147 million kilometers)
from Earth but favorably located for observations in the late evening sky.

The level of hazard will gain even more clarity in 2023, when the
asteroid is approximately 1.1 million miles (1.8 million kilometers)
from Earth. If 2011 AG5 passes through a 227-mile-wide (365-kilometer)
region in space called a keyhole in early February 2023, Earth's
gravitational pull could influence the object's orbital path just enough
to bring it back for an impact on February 5, 2040. If the asteroid
misses the keyhole, an impact in 2040 will not occur.

"Given our current understanding of this asteroid's orbit, there is only
a very remote chance of this keyhole passage even occurring," said Johnson.

Although scientists widely expect it to be a safe flyby, they
acknowledge the slight chance that computed odds could rise as a result
of observations to be taken from 2013 to 2016. According to the experts
at the workshop, even if the odds do increase, there is still ample time
to plan and carry out at least one of several viable missions to change
the asteroid's course.

PHAs are a subset of the larger group of near-Earth asteroids. They have
the closest orbits to Earth's, coming within 5 million miles (about 8
million kilometers). They are large enough to enter Earth's atmosphere
intact and cause damage on at least a local scale. Damage from an
asteroid the size of 2011 AG5 could cover a region at least a hundred
miles wide.

NASA established the NEO Program in 1998 to coordinate the agency's
efforts to detect, track and characterize Earth-approaching NEOs and
comets larger than 1 kilometer in size. The program now also searches
for NEOs as small as object 2011 AG5. NASA supports NEO observation,
tracking and analysis activities worldwide. Activities are coordinated
through the NEO Program Office at JPL.

To read the workshop report and findings, visit:


For information about NASA asteroid missions and activities, visit:




The following documents are available with this release:

    * JPL Report on 2011 AG5

    * The Executive Summary of the JPL Report on 2011 AG5

    * The Consensus Summary for the Goddard Workshop held on May 29, 2012

    * Lindley Johnson's slides presented at the Goddard Workshop on May 29, 2012
Received on Fri 15 Jun 2012 01:24:41 PM PDT

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