NASA in Final Preparations for Nov. 8 Asteroid Flyby

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DC Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

Feature: 2011-332 Oct. 26, 2011

NASA in Final Preparations for Nov. 8 Asteroid Flyby

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-332&cid=release_2011-332

NASA scientists will be tracking asteroid 2005 YU55 with antennas of the agency's Deep Space Network
at Goldstone, Calif., as the space rock safely flies past Earth slightly closer than the moon's orbit on Nov.
8. Scientists are treating the flyby of the 1,300-foot-wide (400-meter) asteroid as a science target of
opportunity – allowing instruments on "spacecraft Earth" to scan it during the close pass.

Tracking of the aircraft carrier-sized asteroid will begin at 9:30 a.m. local time (PDT) on Nov. 4, using the
massive 70-meter (230-foot) Deep Space Network antenna, and last for about two hours. The asteroid
will continue to be tracked by Goldstone for at least four hours each day from Nov. 6 through Nov. 10.
Radar observations from the Arecibo Planetary Radar Facility in Puerto Rico will begin on Nov. 8, the
same day the asteroid will make its closest approach to Earth at 3:28 p.m. PST.

The trajectory of asteroid 2005 YU55 is well understood. At the point of closest approach, it will be no
closer than 201,700 miles (324,600 kilometers) or 0.85 the distance from the moon to Earth. The
gravitational influence of the asteroid will have no detectable effect on anything here on Earth, including
our planet's tides or tectonic plates. Although 2005 YU55 is in an orbit that regularly brings it to the
vicinity of Earth (and Venus and Mars), the 2011 encounter with Earth is the closest this space rock has
come for at least the last 200 years.

During tracking, scientists will use the Goldstone and Arecibo antennas to bounce radio waves off the
space rock. Radar echoes returned from 2005 YU55 will be collected and analyzed. NASA scientists hope
to obtain images of the asteroid from Goldstone as fine as about 7 feet (2 meters) per pixel. This should
reveal a wealth of detail about the asteroid's surface features, shape, dimensions and other physical
properties (see "Radar Love" - http://www.jpl.nasa.gov/news/news.cfm?release=2006-00a ).

Arecibo radar observations of asteroid 2005 YU55 made in 2010 show it to be approximately spherical in
shape. It is slowly spinning, with a rotation period of about 18 hours. The asteroid's surface is darker
than charcoal at optical wavelengths. Amateur astronomers who want to get a glimpse at YU55 will
need a telescope with an aperture of 6 inches (15 centimeters) or larger.

The last time a space rock as big came as close to Earth was in 1976, although astronomers did not know
about the flyby at the time. The next known approach of an asteroid this large will be in 2028.

NASA detects, tracks and characterizes asteroids and comets passing close to Earth using both ground-
and space-based telescopes. The Near-Earth Object Observations Program, commonly called
"Spaceguard," discovers these objects, characterizes a subset of them, and plots their orbits to
determine if any could be potentially hazardous to our planet.

NASA's Jet Propulsion Laboratory manages the Near-Earth Object Program Office for NASA's Science
Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

More information about asteroids and near-Earth objects is at: http://www.jpl.nasa.gov/asteroidwatch .

More information about asteroid radar research is at: http://echo.jpl.nasa.gov/ .

More information about the Deep Space Network is at: http://deepspace.jpl.nasa.gov/dsn .

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