NASA scrambles for better asteroid detection
US: NASA, universities and private groups in the US are
working on asteroid warning systems that can detect objects from space
like the one that struck Russia last week with a blinding flash and
mighty boom.
But the US space agency reiterated that events like the one in the
Urals, which shattered windows and injured nearly 1,000 people, are
rare.
“We would expect an event of this magnitude to occur once every 100
years on average,” said Paul Chodas of NASA's Near-Earth Object Program
Office at the Jet Propulsion Laboratory in Pasadena, California.
NASA estimates that before entering the Earth's atmosphere above
Russia, the asteroid measured 17 meters (56 feet) in diameter and
weighed 10 tons.
Fragments of the asteroid caused an explosion equivalent to 500,000
tons of TNT when they hit.
The same day, a 45-meter in diameter asteroid known as 2012 14
whizzed harmlessly past the Earth, its passage overshadowed by the
bright arc drawn across the Russian sky that same day.
But had it hit ground, 2012 DA14 could have obliterated a large city.
Ten years ago, NASA would not have been able to detect 2012 DA14,
said Lindsey Johnson, near earth object (NEO) project manager at NASA
said recently.
But he said NASA has made progress on learning how to detect small
asteroids.
Johnson said there are many of these objects flying around near the
Earth -- say, half a million -- and they are hard to track because of
their small size.
In line with a goal set by Congress in 1998, NASA has already
discovered and catalogued around 95 percent of the asteroids of a
kilometer or more in diameter that are in the Earth's orbit around the
sun and capable of causing mega-destruction.
The NEO program at NASA currently detects and tracks
Earth-approaching asteroids and comets with land-based and orbiting
telescopes. Scientists estimate their mass and orbit to gauge whether
they pose a danger.
With this system, the Arecibo radio telescope in Puerto Rico, which
has an antenna 305 meters in diameter, can observe with great
sensitivity a third of the night sky and detect asteroids that are on
the large side. All asteroid observations made anywhere in the world by
telescopes, even by amateur star gazers, must be passed on to the Minor
Planet Center, which is financed by NASA and run by the Smithsonian
Astrophysical Observatory for theParis-based International Astronomical
Union.
But in times of tight budgets like these, NASA is trying to develop
other systems specifically capable of tracking small objects in space.
It is financing to the tune of $5 million a project at the University
of Hawaii called Atlas, or Asteroid Terrestrial-Impact Alert System.
Researchers say ATLAS, which will monitor the entire visible sky
every night, will be able to detect objects 45 meters (yards) in
diameter a week before they hit our planet.
For those measuring 150 meters (yards) in diameter, the system --
which could be operational in late 2015 -- will give a three week heads
up.
The goal is to find the objects and give enough advance warning for
measures to be taken to protect people, said John Tonry, the principal
investigator at ATLAS.
The system has enough sensitivity to detect a match flame in New York
City when viewed from San Francisco, for instance. “That's enough time
to evacuate the area of people, take measures to protect buildings and
other infrastructures and be alert to a tsunami danger generated by
ocean impacts,” according to the ATLAS website. But NASA's efforts are
deemed insufficient by former agency astronauts and scientists who last
year launched a project designed to finance, build and launch the first
private space telescope to track asteroids and protect humanity.
The foundation called B612 is trying to raise $450 million to build
and deploy a space telescope that would be called Sentinel and placed in
orbit around the sun, at a distance of 273 million kilometers from the
Earth to detect most objects that are otherwise not visible.
AFP |