NASA in final preparations for November 8 asteroid flyby
Scientists are treating the flyby of the asteroid as a science target of opportunity, allowing instruments on “spacecraft Earth” to scan it during the close pass.
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Jet Propulsion Laboratory, Pasadena, California —
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October 31, 2011 This radar image of asteroid 2005 YU55 was generated from data taken in April of 2010 by the Arecibo Radar Telescope in Puerto Rico. Credit: NASA/Cornell/Arecibo
Tracking the aircraft-carrier-sized asteroid will begin at 9:30 a.m. PDT November 4, using the massive 230-foot (70m) Deep Space Network antenna, lasting for about two hours. The Goldstone facility will continue to track the asteroid for at least four hours each day from November 6 through November 10. Radar observations from the Arecibo Planetary Radar Facility in Puerto Rico will begin November 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 past 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 (2m) per pixel. This should reveal a wealth of detail about the asteroid’s surface features, shape, dimensions, and other physical properties.
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 or larger.
The last time a space rock as big came this 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.
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