NASA Radar Reveals Asteroid Has Its Own Moon

NASA scientists have gathered radar images of asteroid 1998 QE2 and revealed that it is a binary asteroid with a small moon. The images were obtained using the 230-foot (70-meter) Deep Space Network antenna at Goldstone, California. Scientists estimate that the main body (aka the primary asteroid) is approximately 2.7 kilometers (1.7 miles) wide, and it takes less than four hours to rotate. The images of 1998 QE2 also show dark features on its surface. The small body, or moon, is approximately 600 meters (2,000 feet) wide.

Asteroid 1998 QE2 (and its moon) came relatively close to the Earth on May 31, 2013, at 1:59 p.m/ Pacific (20:59 UTC). The asteroid approached at a distance of about 5.8 million kilometers away, which is about 15 times the distance between Earth and the Moon.

This is closer to Earth than the asteroid will get in the next 200 years, so it was a great chance for scientists to gather data on the binary object.

Some interesting facts:

  • Of all the near-Earth asteroids known so far that are 200 meters or larger, about 16 percent are binary or triple systems.
  • Asteroid 1998 QE2 was discovered on Aug. 19, 1998, by the Massachusetts Institute of Technology Lincoln Near Earth Asteroid Research (LINEAR) program near Socorro, N.M.
  • Radar is a powerful technique for studying an asteroids and with radar data scientists can predict an asteroid’s orbit much further into the future.
  • Asteroids 1998 QE2 is a success for NASA’s Near Earth Object Program, which aims to identify objects that may pose a threat for Earth.
First radar images of asteroid 1998 QE2 were obtained when the asteroid was about 3.75 million miles (6 million kilometers) from Earth. The small white dot at lower right is the moon, or satellite, orbiting asteroid 1998 QE2. Image Credit: NASA/JPL-Caltech/GSSR
First radar images of asteroid 1998 QE2 were obtained when the asteroid was about 3.75 million miles (6 million kilometers) from Earth. The small white dot at lower right is the moon, or satellite, orbiting asteroid 1998 QE2. Image Credit: NASA/JPL-Caltech/GSSR

You can visit the JPL Small-Body Database Browser at http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=285263;orb=1 for detailed information about the orbital trajectory of asteroid 1998 QE2. Credit: JPL
You can visit the JPL Small-Body Database Browser at http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=285263;orb=1 for detailed information about the orbital trajectory of asteroid 1998 QE2. Credit: JPL

Why is this research important to Astrobiology?

NASA tracks near Earth objects, like asteroids and comets, to assess whether or not they could collide with planet Earth. Impact events can be devistating, and may have been responsible in part for numerous extinction events in Earth’s history. Future impacts could affect the habitability of our planet, and determining factors that affect the future of life on Earth is an important goal of the Astrobiology Program at NASA.

Check out some other Near Earth Objects that have recently made the news:

 

 


Radar data of asteroid 1998 QE2 obtained on May 29, 2013. The small moving white dot is the moon, or satellite, orbiting asteroid 1998 QE2. Available at: http://www.nasa.gov/multimedia/videogallery/index.html?media_id=163878681


Astrobiology Magazine contacted Dr. Donald K. Yeomans, Manager of the NASA Near Earth Object Program Office at the Jet Propulsion Laboratory with some additional questions:

Astrobiology Magazine: How much damage would QE2 cause if it struck a city?  How does the damage compare to the recent meteor that struck Russia?

Don Yeomans: 2008 QE2, at about 3 km in extent, is one of the larger near-Earth asteroids and in the very unlikely event that an object this size should hit the Earth it would do far more damage than taking out a city (assuming it hit in a populated area of the Earth).  It would cause serious global problems and possibly an extinction event.  I don’t like the term "city killers" but an object of about 30 meters would be expected to destroy a city-sized region if it were to hit Earth at the right place.  There are millions of 30 meter and larger objects in near-Earth space. 

There is no comparison between a hit by a 3 km sized object and one the size of the object that hit the Earth’s atmosphere over Chelyabinsk (about 20 meters).  The Chelyabinsk object created an impact energy equivalent to 440 kilotons of TNT explosives while a 3 km asteroid hit would be expectd to create an impact energy of about 2 million megatons of equivalent energy.  The 3 km object’s impact energy would be 4.5 million times larger than the Chelyabinsk event.  Having said that, there are only about 1000 near-Earth asteroids larger than one kilometer and 95% of them have been found.  None represent a threat to Earth in the foreseeable future.

AM: The asteroid has carbon and amino acids. Is this typical for asteroids that would have struck the early Earth? >How important would such asteroid impacts have been for the development of life on Earth?

Yeomans: 2008 QE2 is a C-type asteroid and would be expected to contain carbon-based materials and amino acids.  The amino acids are inferred because meteorites that are thought to arrive from C-type asteroids have been found to contain amino acids.  I think it is fair to say that an early bombardment of the Earth by comets and asteroids laid down a veneer of carbon-based organics and water, with the water coming from cometary ices or the ices (or hydrated minerals) in asteroids.

AM: Would binary asteroids such as QE 2 be more difficult to deflect from than single asteroids?

Yeomans: Deflecting a binary asteroid would not be more difficult than deflecting a solitary object.  Just gently deflect the primary and the secondary will follow along.


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