Zipping Through the Neighborhood

Summary (Jan 27, 2008): An asteroid is set to make a rare and close flyby of Earth on January 29. It poses no threat to the planet, but may put on a show in the night sky for amateur astronomers.

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Zipping Through the Neighborhood

Based on a JPL news release

Asteroid to Make Rare Close Flyby of Earth January 29

Asteroid 2007 TU24 taken by the Catalina Sky Survey, Oct. 12, 2007.
Credit: Steve Larson and Ed Beshore, Catalina Sky Survey

Scientists are monitoring the orbit of asteroid 2007 TU24. The asteroid is expected to fly past Earth on Jan. 29, with its closest distance being about 537,500 kilometers (334,000 miles) at 12:33 a.m. Pacific time (3:33 a.m. Eastern time). It should be observable that night by amateur astronomers with modest-sized telescopes.

Scientists at NASA's Jet Propulsion Laboratory in Pasadena, California obtained the first images of asteroid 2007 TU24 using high-resolution radar data. The data indicate the asteroid is somewhat asymmetrical in shape, with a diameter roughly 250 meters (800 feet) in size.

Asteroid 2007 TU24 was discovered by the NASA-sponsored Catalina Sky Survey on Oct. 11, 2007. Scientists at NASA's Near-Earth Object Program Office at JPL have determined that there is no possibility of an impact with Earth in the foreseeable future.

"This will be the closest approach by a known asteroid of this size or larger until 2027," said Don Yeomans, manager of the Near Earth Object Program Office. "As its closest approach is about one-and-a-half times the distance of Earth to the moon, there is no reason for concern. On the contrary, Mother Nature is providing us an excellent opportunity to perform scientific observations."

The illustration from an amateur astronomer shows the asteroid's track on the sky for 3 days near the time of the close Earth approach as seen from the city of Philadelphia.
Credit: Dr. Dale Ireland, Silverdale, WA.

The first radar detection of the asteroid was acquired on Jan. 23 using the Goldstone 70-meter (230-foot) antenna. The Goldstone antenna is part of NASA's Deep Space Network Goldstone station in Southern California's Mojave Desert.

Goldstone's 70-meter diameter (230-foot) antenna is capable of tracking a spacecraft traveling more than 16 billion kilometers (10 billion miles) from Earth. The surface of the 70-meter reflector must remain accurate within a fraction of the signal wavelength, meaning that the precision across the 3,850-square-meter (41,400-square-foot) surface is maintained within one centimeter (0.4 inch).

Steve Ostro, JPL astronomer and principal investigator for the project, plans for his team to conduct more radar observations of asteroid 2007 TU24 using the National Science Foundation's Arecibo Observatory in Puerto Rico on Jan. 27-28 and Feb. 1-4. Scientists working with Ostro on the project include Lance Benner and Jon Giorgini of JPL, Mike Nolan of the Arecibo Observatory, and Greg Black of the University of Virginia.

These low-resolution radar images of asteroid 2007 TU24 were taken over a few hours by the Goldstone Solar System Radar Telescope in California's Mojave Desert. Image resolution is approximately 20-meters per pixel. When the asteroid passes close to Earth, a combination of several telescopes will provide higher resolution images.
Credit: NASA/JPL-Caltech

Asteroid 2007 TU24 will reach an approximate apparent magnitude 10.3 on Jan. 29-30 before quickly becoming fainter as it moves farther from Earth. On that night, the asteroid will be observable in dark and clear skies through amateur telescopes with apertures of at least 7.6 centimeters (3 inches). An object with a magnitude of 10.3 is about 50 times fainter than an object just visible to the naked eye in a clear, dark sky.

NASA detects and tracks asteroids and comets passing close to Earth. The Near Earth Object Observation Program, commonly called "Spaceguard," discovers, characterizes and computes trajectories for these objects to determine if any could be potentially hazardous to our planet.

In the past, asteroids and comets have had a profound influence on Earth's biosphere. Asteroid impacts may have played a role in some of the most catastrophic mass extinctions in our planet's history. However, asteroid and comet impacts on the early Earth may have also delivered water and precursor molecules vital for life's origin. The close encounter with asteroid 2007 TU24 will simply provide scientists with a unique opportunity to study an asteroid from a relatively close distance.

For more information, visit http://neo.jpl.nasa.gov.

Related Web Sites

Analyzing Apophis
Holding Fast to an Asteroid
Two-Way Asteroid Trip
Great Impact Debate I: Benefits of Hard Bodies

Note: Meteors, Comets and Asteroids

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Sunday, January 27, 2008