Searching for potentially
Earth-destroying asteroids today isn't easy.
They're dark, difficult to see
from the surface of the planet, and there are a lot of them floating in the
solar system. Scientists are now looking into new, higher-tech ways to find and
track near-Earth objects, but for now, much of the hard work of asteroidtracking
is done the old-fashioned way: with a telescope on a clear night.
NASA scientists, astronomers
around the world and amateur observers with backyard telescopes devote their
lives and free time to seeking out potentially hazardous near-Earth objects
(NEOs). [Photos:
Potentially Dangerous Asteroids]
"It all begins with an observer
making observations," Gareth Williams, of the Minor Planet Center, the
clearinghouse for asteroid and other minor-planet documentation, told SPACE.com
"They can be observing known objects, or they can be searching for new
objects, but even if they're searching for known objects — just to take a
pretty picture or some reason — new objects can come into the field. About one
in 1,000 of these new objects turn out to be an object that's moving
anomalously when compared to other objects in the frame."
Hunting asteroids
Anomalous motion — when an object
moves in a different way than other bodies in a frame — can signal something to
a keen observer. The skywatcher then reports his or her findings to the Minor
Planet Center (MPC), located in Cambridge, Mass., and officials with the MPC
search the organization's database to try to find a match with known,
already-tracked objects.
If the new observation doesn't
match any known object, the MPC puts it onto the NEO confirmation page — a
database where observers can find information about asteroids with orbits that
have not been sufficiently traced.
The MPC functions as the central
database for all information about NEOs. The astronomers of the MPC — run by
the International Astronomical Union — collect and help verify all of the
space-rock sightings that are reported.
An interconnected group of
observers and sky surveys work to validate claims of near-Earth-object
sightings on a daily basis. This month alone, observers have discovered 80 NEOs
out of 656,546 observations.
Tip of the asteroid iceberg
So far, observers around the
world have found and tracked more than 10,000
near-Earth objects. Astronomers have found more than 90 percent of
the possibly "world-ending" cosmic objects that could threaten Earth,
but tracking anything smaller than 0.6 miles (1 kilometer) across is more
difficult.
"NASA has not even come
close to finding and tracking the 1 million smaller asteroids that might only
just wipe out a city, or perhaps collapse the world economy if they hit in the
wrong place," Ed Lu, CEO of the B612 Foundation, a nonprofit working to
buildSentinel
asteroid observatory, a NEO-hunting space telescope, said in April.
In all, less than 10 percent of
asteroids measuring about 459 feet (140 meters) across have been found, whereas
about 1 percent of asteroids measuring 131 feet (40 m) in diameter have been
tracked. While an impact caused by these relatively small space rocks wouldn't
cause a worldwide disaster, they could induce some regional issues.
The Sentinel space telescope is
designed to hunt for these small potentially city-destroying objects. The
spacecraft would scan the solar system in infrared light, making dark asteroids
easier to see.
Finding near-Earth objects could
also make it easier for asteroid mining companies and NASA engineers to devise
strategies to launch future manned or unmanned missions to NEOs.
Earth occasionally captures a
cosmic object in its gravity, creating a transitory "minimoon"
before the space rock zips off to another part of the solar system. The tiny
asteroids, usually only about 3 feet (1 m) in diameter, can get caught in the
planet's orbit for about a year, possibly allowing scientists to launch a
mission aimed at investigating (or even mining) the space rock.
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