Space
10:35 pm
Thu February 7, 2013

Close Shave: Asteroid To Buzz Earth Next Week

Originally published on Thu March 20, 2014 11:36 am

An asteroid the size of an office building will zoom close by Earth next week, but it's not on a collision course, NASA says.

Still, some people think this near-miss should serve as a wake-up call.

"It's a warning shot across our bow that we are flying around the solar system in a shooting gallery," says Ed Lu, a former astronaut and head of the B612 Foundation, a nonprofit dedicated to protecting humanity from asteroids.

The asteroid known as 2012 DA14 was first spotted last year by astronomers in Spain. It's thought to be about 150 feet across and made of rock.

It will whiz past Earth on Feb. 15, going about 5 miles per second. At its closest approach, it will be only about 17,200 miles above the surface of our planet. That's far nearer to us than the moon, and even closer than some weather and communications satellites.

NASA officials say this event is one for the record books — the first time scientists have been able to predict something so big coming so close.

"There really hasn't been a close approach that we know about for an object of this size," says Donald Yeomans, manager of the Near Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

It will come closer than satellites in a geosynchronous orbit around 22,000 miles up, but is extremely unlikely to hit any of those as it goes by.

"This asteroid seems to be passing in the sweet spot between the GPS satellites and the communications and weather satellites," Yeomans says.

Its flight path is well-understood enough to know that there's no chance it will hit the Earth.

That's a good thing, because if an asteroid this size did smack our planet, it could cause a huge amount of destruction — the equivalent of 2.4 million tons of TNT, Yeomans says. Such an impact would be comparable to the famous "Tunguska event" of 1908, when a space object of a similar size collided with Earth over Siberia and leveled millions of trees in an area of more than 820 square miles.

That kind of impact is only expected to happen once every 1,200 years or so, Yeomans says. But next week's close flyby shows that the threat from asteroids is real and can't be ignored, Lu says.

"The fact that this was only discovered a year ago highlights the problem," says Lu, who points out that if this particular asteroid had been headed straight for us, there'd be no time to do something like send up a spacecraft to try to nudge it off course.

"There's no way we could have stopped this. Nothing we could have done," Lu says. "The only thing we could have done, if this was going to hit us, was to evacuate the area."

Our planet orbits the sun in a swarm of space rocks, Lu says, and though NASA does surveys looking for the biggest ones, most of the asteroids out there haven't been discovered.

"We only know the locations and trajectories of about 1 percent of asteroids this size or larger," Lu says. "So for every one of these, there's 99 out there we don't know about."

That's why his group is working to build and launch a private space telescope that would search for asteroids, and find them before they find us.

An official at NASA headquarters said the agency is continually looking for ways to improve its ability to spot smaller asteroids — within the constraints of its budget.

Copyright 2014 NPR. To see more, visit http://www.npr.org/.

Transcript

DAVID GREENE, HOST:

The astrophysicist Neil deGrasse Tyson once said on this program that humans would be the embarrassment of the galaxy if we had the power to deflect an asteroid, and then failed and then went extinct. First things first: There is no risk of this happening anytime soon. That said, a week from today, an asteroid the size of an office building will zoom by relatively close to Earth.

It will be far nearer to us than the moon, and even closer than some weather and communication satellites. Luckily, this asteroid is not on a collision course with our planet. NPR's Nell Greenfieldboyce reports that some people think this near-miss should be a wakeup call, though.

NELL GREENFIELDBOYCE, BYLINE: The asteroid is called 2012 DA14. It's thought to be about 150 feet across and made of rock. On February 15th, it will whizz past Earth, going about five miles per second. And it will pass by only around 17,000 miles above the surface of our planet. NASA officials say this event is one for the record books: the first time scientists have been able to predict something so big coming so close.

DON YEOMANS: And there really hasn't been a close approach that we know about for an object of this size.

GREENFIELDBOYCE: Don Yeomans is manager of the Near Earth Object office at NASA's Jet Propulsion Lab. He says it will come closer than some satellites that orbit around 22,000 miles up, but is extremely unlikely to hit any of those as it goes by.

YEOMANS: This asteroid seems to be passing in the sweet spot between the GPS satellites and the communications and weather satellites.

GREENFIELDBOYCE: And scientists know for sure that it definitely won't hit Earth. That's a good thing, because if it did it, would be like setting off 2.4 million tons of TNT.

YEOMANS: Should something of this size hit, it would be comparable to what happened in June of 1908, the so-called Tunguska event.

GREENFIELDBOYCE: That's when a space object of a similar size collided with the Earth over Siberia.

YEOMANS: And caused significant ground damage, leveling millions of trees for over 820 square miles.

GREENFIELDBOYCE: He says that kind of impact is only expected to happen once every 1,200 years or so. Still, some say that historic event, plus next week's flyby, shows that the threat from asteroids is real and can't be ignored.

ED LU: It's a warning shot across our bow that we are flying around the solar system in a shooting gallery.

GREENFIELDBOYCE: Ed Lu is a former astronaut and head of the B612 Foundation. That's a nonprofit dedicated to protecting humanity from asteroids. He says: Our planet orbits the sun in a swarm of space rocks. And even though NASA does surveys looking for the biggest ones, most of the asteroids out there haven't been discovered.

LU: We only know the locations and trajectories of about 1 percent of asteroids this size or larger. So, you know, for every one of these, there's 99 out there we don't know about.

GREENFIELDBOYCE: Lou notes that asteroid DA14 was only spotted last year, by astronomers in Spain.

LU: The fact that this was only discovered a year ago highlights the problem.

GREENFIELDBOYCE: He says if this asteroid had been on track to collide with us, we wouldn't have had enough time to do something like send up a spacecraft to nudge it off course.

LU: There's no way we could have stopped this, nothing we could have done. The only thing we could have done, if this was going to hit us, was to evacuate the area.

GREENFIELDBOYCE: That's why his group is working to build and launch a private space telescope that would search for asteroids. They have an agreement with NASA to work on it. An official at NASA headquarters said that the agency is continually looking for ways to improve their ability to spot smaller asteroids within the constraints of their budget. Nell Greenfieldboyce, NPR News. Transcript provided by NPR, Copyright NPR.

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