LOS ANGELES, July 5 (Xinhua) -- U.S. scientists have
urged the U.S. government to take further defensive measures against near-Earth
objects, The Los Angeles Times reported on Saturday.
The United States was not doing enough to defend the
planet against the dangers posed by near-Earth objects, said a group of
scientists who observed the 100th anniversary of the Tunguska asteroid event
this week in Los Angeles.
"We are not prepared at this time to prevent the
massive death and destruction that would occur if an object from space hit the
Earth as it did in Tunguska" in Siberia, said Republican Congressman Dana
Rohrabacher who joined the scientists in the event.
He was referring to an explosion in the air above
Tunguska, a remote river valley in eastern Russia on June 30, 1908, which
flattened trees over an 800-square-mile (1280-square-kilometer) area, but no one
was killed. Although no one is positive what caused the Tunguska event, most
scientists believe an asteroid about 150 feet across exploded.
If an asteroid the size of the one believed to have
exploded in the air above Tunguska were to explode over Los Angeles, the
destruction would be greater, Rohrabacher told a news conference at the Pasadena
offices of the Planetary Society in Los Angeles.
NASA has established a Near-Earth Object Program
Office at the Jet Propulsion Laboratory in Southern California to monitor
potentially dangerous asteroids. The most scrutinized is Apophis, which has
about a one-in-45,000 chance of hitting Earth in 2036, according to Don Yeomans,
manager of the Near-Earth Object Program Office. Apophis is about five times the
suspected size of the Tunguska object.
But Alan Harris, a senior research scientist at the
Space Science Institute in Boulder, Colorado, said the greatest danger does not
come from the objects we know about but from the ones we haven't identified.
In one example of the lack of attention the issue is
receiving in Washington, Rohrabacher said, funding for the Arecibo, Puerto Rico,
radio telescope, which hunts near-Earth objects, is in danger in next year's
If scientists are able to identify a potential killer
asteroid, the deeper question is how to deflect it.
Theorists have proposed a variety of possible
solutions, including using a nuclear weapon to blow it up or sending a
spacecraft that would use gravity to drag the object off its destructive path.