May 30, 2013

Big Asteroid Flyby

May 30, 2013: Here we go again. Another asteroid is paying a visit to the Earth-Moon system.

Asteroids have been a hot topic since February 15th  when one small asteroid exploded over Russia and another larger one, 2012 DA14, made a record setting close approach to Earth on the same day. This time the interloper is 1998 QE2, a potentially hazardous asteroid 2.7 km in diameter.  Astronomers are preparing to study the space rock as it harmlessly passes by on May 31st.

"This is a big asteroid that's going to be one of the best radar imaging targets of the year," says Lance Benner of NASA's Jet Propulsion Laboratory.

Big Asteroid Flyby (splash)
A new ScienceCast video previews the near-Earth flyby of massive asteroid 1998 QE2. Play it

"As my old friend, radar astronomer Steve Ostro used to say, spaceship Earth is making a flyby of the asteroid, so we're going to exploit the capabilities of the radars to understand as much as possible."

At closest approach on May 31st, the asteroid will be 5.8 million kilometers from Earth, about 15 times farther than the Moon.

"At that range, both the Goldstone and Arecibo radars should be able to make detailed images of 1998 QE2," says Benner. "The radar maps should rival images of other asteroids obtained by spacecraft during flyby missions."

Big Asteroid Flyby (moon anim, 200px)
On May 30th, NASA's Goldstone radar detected a moon orbiting asteroid 1998 QE2. More

One thing that intrigues Benner is the asteroid's dark complexion. According to measurements by the Spitzer Space Telescope, 1998 QE2 reflects only 6% of the sunlight that falls on it, which makes it blacker than coal. "Consequently, it could have a composition similar to that of 101955 Bennu, the target of NASA's OSIRIS-REx mission," he says.

Due to launch in 2016, the OSIRIS-REx spacecraft will travel to near-Earth asteroid Bennu, study it from orbit, and ultimately bring back a sample for laboratory study on Earth. Near-Earth asteroid Bennu interests researchers for two reasons:  First, it is a carbon-rich asteroid that could harbor amino acids and other organic molecules essential to primitive life. Second, it's the kind of asteroid that NASA ultimately might want to capture. Indeed, the OSIRIS-REx mission is considered to be a vital part of NASA's plans to find, study and relocate an asteroid for exploration by astronauts.

Perhaps 1998 QE2 will give researchers a sneak preview of this fascinating space rock.

Although the closest approach is on May 31st, the best time to observe 1998 QE2 will be during the first week of June when the asteroid enters northern skies. At that time, its sunlit side will face Earth, making it an easy target for large backyard telescopes.  At maximum brightness on June 3rd and 4th it is expected to glow like an 11th magnitude star.

While amateur astronomers watch the space rock glide through the constellations Libra and Ophiuchus, NASA radars will be pinging the space rock with powerful bursts of radio energy, revealing an alien landscape that no one has ever seen before.

Stay tuned for updates.


Author: Dr. Tony Phillips Production editor: Dr. Tony Phillips | Credit: Science@NASA

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