Large
asteroid heading to Earth? Pray, says NASA
NASA
chief Charles Bolden has advice on how to handle a large asteroid
headed toward New York City: Pray.
20
March, 2013
That's
about all the United States - or anyone for that matter - could do at
this point about unknown asteroids and meteors that may be on a
collision course with Earth, Bolden told lawmakers at a U.S. House of
Representatives Science Committee hearing on Tuesday.
An
asteroid estimated to be have been about 55 feet in diameter exploded
on February 15 over Chelyabinsk, Russia, generating shock waves that
shattered windows and damaged buildings. More than 1,500 people were
injured.
Later
that day, a larger, unrelated asteroid discovered last year passed
about 17,200 miles from Earth, closer than the network of television
and weather satellites that ring the planet.
The
events "serve as evidence that we live in an active solar system
with potentially hazardous objects passing through our neighborhood
with surprising frequency," said Representative Eddie Bernice
Johnson, a Texas Democrat.
"We
were fortunate that the events of last month were simply an
interesting coincidence rather than a catastrophe," said
Committee Chairman Lamar Smith, a Texas Republican, who called the
hearing to learn what is being done and how much money is needed to
better protect the planet.
NASA
has found and is tracking about 95 percent of the largest objects
flying near Earth, those that are .62 miles or larger in diameter.
"An
asteroid of that size, a kilometer or bigger, could plausibly end
civilization," White House science advisor John Holdren told
legislators at the same hearing.
But
only about 10 percent of an estimated 10,000 potential "city-killer"
asteroids, those with a diameter of about 165 feet have been found,
Holdren added.
On
average, objects of that size are estimated to hit Earth about once
every 1,000 years.
"From
the information we have, we don't know of an asteroid that will
threaten the population of the United States," Bolden said. "But
if it's coming in three weeks, pray."
In
addition to stepping up its monitoring efforts and building
international partnerships, NASA is looking at developing
technologies to divert an object that may be on a collision course
with Earth.
"The
odds of a near-Earth object strike causing massive casualties and
destruction of infrastructure are very small, but the potential
consequences of such an event are so large it makes sense to takes
the risk seriously," Holdren said.
About
66 million years ago, an object 6 miles in diameter is believed to
have smashed into what is now the Yucatan Peninsula in Mexico,
leading to the demise of the dinosaurs, as well as most plant and
animal life on Earth.
The
asteroid that exploded over Russia last month was the largest object
to hit Earth's atmosphere since the 1908 Tunguska event when an
asteroid or comet exploded over Siberia, leveling 80 million trees
over more than 830 square miles (2,150 sq km).
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