20 August 2008

Russian expert says nuclear devices can defend against asteroids

Russian expert says nuclear devices can defend against asteroids
RIA Novosti
01/07/2008 18:45
MOSCOW, July 1 (RIA Novosti) - Nuclear explosive devices are the most effective means of protecting Earth from possible collisions with space bodies, including comets and asteroids, a Russian nuclear physicist told RIA Novosti on Tuesday.
Scientists around the world have long been seeking means of protecting the Earth from the threat of dangerous Near Earth Objects (NEOs). Scientists say such collisions pose a threat on average once every 200-1,000 years.
Vadim Simonenko, deputy head of the Russian Federal Nuclear Center, believes that nuclear explosive devices are more energy efficient, compact and less heavy than lasers or the so-called "gravitational tractors" in terms of their practical application as "weapons against NEOs."
"We in Russia have a wealth of experience in the controlled use of nuclear explosions for peaceful purposes," Simonenko said. "A nuclear device in skillful hands is like a scalpel in the hands of a surgeon."
The scientist said special nuclear devices must be created for effective use against NEOs. In order to disperse an asteroid with diameter of up to 100 meters, these devices must have a yield of about one megaton of TNT equivalent, and weigh several hundred kilograms.
"It is a difficult technical task but it can be accomplished. Besides, there is no need for actual testing [of these devices] because it may be done through computer modeling," he said.
Existing nuclear devices, both military and civilian, were created for specific purposes and do not meet the requirements for "precision strikes" against NEOs, especially comets, which are less predictable than asteroids, Simonenko said.
An earlier report at a Moscow scientific conference said 99942 Apophis, or Asteroid 2004 MN4, with a diameter of 350 meters, currently poses biggest space threat to Earth.
In 2029, this NEO will be at a distance of only 36,000 km (22,400 miles) - closer than satellites in geostationary orbit. Earth's gravity could alter the path of Apophis in such a way that it would collide with Earth on its next approach in 2036.
The explosion could surpass the famous Tunguska explosion of June 30, 1908, which affected a 2,150 square kilometer (830 sq miles) area of Russia felling over 80 million trees in the Krasnoyarsk Territory in Siberia.
Some researchers believe, however, that blowing up NEOs in space poses could result in large fragments surviving the fiery passage through the atmosphere and still hitting the planet.
They propose a more cautionary approach toward dealing with NEOs, by deflecting them from their collision path toward the Earth.
"Deflection is the most favorable strategy, but it requires a considerable early warning period - up to a few years," Simonenko said. "We may not have such a luxury because small asteroids [100-150 m in diameter] are hard to detect."

Following are reports on the status of the Russian efforts toward planetary defense. The information has been communicated by Vadim Simonenko and Anatoly Zaitsev of the Russian Federal Nuclear Center at Snezhinsk (Chelyabinsk-70). It is primarily the results of three meetings of the Space Protection of the Earth conference.

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