Washington: Lowa State University engineers are developing ideas and technologies to save the Earth from potentially hazardous asteroids.
Recent events have certainly highlighted the threat of asteroid strikes. There was the 15-meter (49-foot) meteor that exploded an estimated 12 miles over Chelyabinsk, Russia, on Feb. 15, damaging buildings and injuring more than 1,000 people. That same day, the 45-meter (148-foot) asteroid 2012 DA14 passed within 17,200 miles of Earth.
"It's not a laughing matter," said Bong Wie, the director of the Asteroid Deflection Research Center at Iowa State University and the Vance D. Coffman Faculty Chair and professor of aerospace engineering.
"DA14 was a serious near miss," Wie said. "If that impact had happened, it would have been the equivalent of 160 Hiroshima nuclear bombs.
Wie's studies lead him to believe it will take a one-two nuclear punch to break an asteroid into harmless pieces when there isn't sufficient warning to use non-nuclear defenses.
Here's how it would work:
A satellite carrying a nuclear device would be launched into orbit.
The satellite's trajectory would intercept an incoming asteroid that's 50 to 300 meters (164 to 984 feet) across, the typical size that threatens Earth. The satellite could travel up to 30 days to reach the asteroid.
The satellite would hit the asteroid at a speed of 10 kilometers (6.2 miles) per second, creating a large crater in the asteroid.
Just before impact, the nuclear device would be released from the back of the satellite, creating a slight delay in detonation and allowing the device to fly into the middle of the crater.
The explosion from inside the crater would blast the asteroid apart.
"The overall effect of an explosion under the surface is 20 times larger than an explosion on the surface," Wie said.
The asteroid chunks would spread into a large debris cloud. By the time Earth reached the cloud, Wie said less than 0.1 percent of the chunks would enter the atmosphere. And those should only be 5-meter (16-foot) pieces that aren't likely to do much harm.
We have all the technology to make it work, Wie said.
"We don't need anything new. But we need to engineer, integrate and assemble these technologies. And we need practice," he said.
To date, Wie, his Iowa State research team and Brent Barbee of NASA's Goddard Space Flight Center in Maryland have been working with data generated by computer simulations.
Wie said it's time to integrate the necessary technology, build an unarmed prototype satellite and launch an actual test to see if a target asteroid can be hit.
NASA engineers and scientists have already accomplished a very similar mission.
In July 2005, the impactor from NASA's Deep Impact Mission crashed into Tempel 1, a comet that measures 7.6 by 4.9 kilometers (4.7 by 3 miles). The impact was designed to create a crater 25 meters deep (82 feet) and 100 meters wide (328 feet), exposing the comet's interior. The mission's flyby spacecraft passed over the crater to take pictures and collect spectroscopy data.
"We have done that with a large comet," Wie said, "but not with a 300-meter or a 50-meter asteroid."
So, Wie is writing up a proposal for a 500-million-dollar test mission.
"Now is the time to talk about a test mission. It is time to develop a plan and demonstrate this concept," he said.
Wie has just been invited to show off his research as part of NASA's Technology Day on the Hill in Washington, D.C., on April 17.
First Published: Friday, March 08, 2013, 11:31