[meteorite-list] Earth Flyby of 'Space Peanut' Captured in New Video (Asteroid 1999 JD6)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 31 Jul 2015 15:22:21 -0700 (PDT)
Message-ID: <201507312222.t6VMMLhs004685_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?feature=4675

Earth Flyby of 'Space Peanut' Captured in New Video
Jet Propulsion Laboratory
July 31, 2015

[Images]
Radar images of asteroid 1999 JD6 were obtained on July 25, 2015. The
asteroid is between 660 - 980 feet (200 - 300 meters) in diameter. Image
credit: NASA/JPL-Caltech/GSSR

NASA scientists have used two giant, Earth-based radio telescopes to bounce
radar signals off a passing asteroid and produce images of the peanut-shaped
body as it approached close to Earth this past weekend.

The asteroid appears to be a contact binary -- an asteroid with two lobes
that are stuck together.

The images show the rotation of the asteroid, named 1999 JD6, which made
its closest approach on July 24 at 9:55 p.m. PDT (12:55 a.m. EDT on July
25) at a distance of about 4.5 million miles (7.2 million kilometers,
or about 19 times the distance from Earth to the moon).

"Radar imaging has shown that about 15 percent of near-Earth asteroids
larger than 600 feet [about 180 meters], including 1999 JD6, have this
sort of lobed, peanut shape," said Lance Benner of NASA's Jet Propulsion
Laboratory in Pasadena, California, who leads NASA's asteroid radar research
program.

To obtain the views, researchers paired NASA's 230-foot-wide (70-meter)
Deep Space Network antenna at Goldstone, California, with the 330-foot
(100-meter) National Science Foundation Green Bank Telescope in West Virginia.
Using this approach, the Goldstone antenna beams a radar signal at an
asteroid and Green Bank receives the reflections. The technique, referred
to as a bistatic observation, dramatically improves the amount of detail
that can be seen in radar images. The new views obtained with the technique
show features as small as about 25 feet (7.5 meters) wide.

The individual images used in the movie were generated from data collected
on July 25. They show the asteroid is highly elongated, with a length
of approximately 1.2 miles (2 kilometers) on its long axis. The movie
spans a period of about seven hours, 40 minutes.

This week's flyby was the closest approach the asteroid will make to Earth
for about the next 40 years. The next time it will approach Earth this
closely is in 2054, at approximately the same distance of this week's
flyby.

Data from the new observations will be particularly useful to Sean Marshall,
a graduate student at Cornell University in Ithaca, New York, whose doctoral
research on 1999 JD6 is funded by NASA's Near-Earth Object Program. "I'm
interested in this particular asteroid because estimates of its size from
previous observations, at infrared wavelengths, have not agreed. The radar
data will allow us to conclusively resolve the mystery of its size to
better understand this interesting little world," he said.

Despite the uncertainty about its size, asteroid 1999 JD6 has been studied
extensively and many of its physical properties, as well as its trajectory,
are well known. It rotates in just over seven-and-a-half hours and is
thought to be a relatively dark object. Asteroid 1999 JD6 was discovered
on May 12, 1999, by the Lowell Observatory Near-Earth-Object Search, located
in Flagstaff, Arizona.

Radar is a powerful technique for studying an asteroid's size, shape,
rotation, surface features and surface roughness, and for improving the
calculation of asteroid orbits. Radar measurements of asteroid distances
and velocities often enable computation of asteroid orbits much further
into the future than would be possible otherwise.

NASA places a high priority on tracking asteroids and protecting our home
planet from them. In fact, the U.S. has the most robust and productive
survey and detection program for discovering near-Earth objects (NEOs).
To date, U.S. assets have discovered over 98 percent of the known NEOs.

In addition to the resources NASA puts into understanding asteroids, it
also partners with other U.S. government agencies, university-based astronomers,
and space science institutes across the country, often with grants, interagency
transfers and other contracts from NASA, and also with international space
agencies and institutions that are working to track and better understand
these objects.

NASA's Near-Earth Object Program at NASA Headquarters, Washington, manages
and funds the search, study and monitoring of asteroids and comets whose
orbits periodically bring them close to Earth. JPL 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 available at:

http://neo.jpl.nasa.gov

http://www.jpl.nasa.gov/asteroidwatch

and via Twitter at

http://www.twitter.com/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


Media Contact

DC Agle / Preston Dyches
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011 / 818-354-7013
agle at jpl.nasa.gov / pdyches at jpl.nasa.gov

2015-254
Received on Fri 31 Jul 2015 06:22:21 PM PDT