NASA Releases Workshop Data and Findings on Asteroid 2011 AG5

June 15, 2012

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown@nasa.gov

RELEASE: 12-189

NASA RELEASES WORKSHOP DATA AND FINDINGS ON ASTEROID 2011 AG5

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:

http://neo.jpl.nasa.gov/

For information about NASA asteroid missions and activities, visit:

http://www.nasa.gov/asteroids

EDITOR'S NOTE: Lindley Johnson and Don Yeomans are available for media
interviews. To coordinate a time and date, email Dwayne Brown at
dwayne.c.brown@nasa.gov.


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