Nuclear One-Two Punch Could Knock Out Dangerous Asteroid
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Destroying a dangerous asteroid with a nuclear bomb is a well-worn trope of science fiction, but it could become reality soon enough.
Scientists are developing a mission concept that would blow apart an Earth-threatening asteroid with a nuclear explosion, just like Bruce Willis and his oilmen-turned-astronaut crew did in the 1998 film "Armageddon."
But unlike in the movie, the spacecraft under development — known as the Hypervelocity Asteroid Intercept Vehicle, or HAIV — would be unmanned. It would hit the space rock twice in quick succession, with the non-nuclear first blow blasting out a crater for the nuclear bomb to explode inside, thus magnifying its asteroid-shattering power.
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"Using our proposed concept, we do have a practically viable solution — a cost-effective, economically viable, technically feasible solution," study leader Bong Wie, of Iowa State University, said Wednesday (Nov. 14) at the 2012 NASA Innovative Advanced Concepts (NIAC) meeting in Virginia. [5 Reasons to Care About Asteroids]
When, not if
Earth has been pummeled by asteroids throughout its 4.5-billion-year history, and some of the strikes have been catastrophic. For example, a 6-mile-wide (10 kilometers) space rock slammed into the planet 65 million years ago, wiping out the dinosaurs.
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Earth is bound to be hit again, and relatively soon. Asteroids big enough to cause serious damage today — not necessarily the extinction of humans, but major disruptions to the global economy — have hit the planet on average every 200 to 300 years, researchers say.
So humanity needs to have a plan in hand to deal with the next threatening asteroid, many scientists stress.
That plan should include deflection strategies, they say. Given a few decades of lead time, a threatening space rock could be nudged off course — perhaps by employing a tag-along "gravity tractor" probe, or even by painting the asteroid white and letting sunlight give it a push.
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But humanity also needs to be prepared for an asteroid that pops up on scientists' radar just weeks before a potential impact. That scenario might demand the nuclear option that Wie and his colleagues are working to develop.
A one-two punch
NASA engineers identified 168 technical flaws in "Armageddon," Wie said. But one thing the movie got right is the notion that a nuke will be far more effective if it explodes inside an asteroid rather than at its surface. (At a depth of 10 feet, or 3 meters, the bomb's destructive power would be about 20 times greater, Wie said.)
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So Wie and his team came up with a way to get the bomb down into a hole, without relying on a crew of spacewalking roughnecks to bore into the space rock.
The HAIV spacecraft incorporates two separate impactors, a "leader" and a "follower." As HAIV nears the asteroid, the leader separates and slams into the space rock, blasting out a crater about 330 feet (100 m) wide.
The nuke-bearing follower hits the hole a split-second later, blowing the asteroid to smithereens. Simulations suggest the explosion would fling bits of space rock far and wide, leaving only a tiny percentage of the asteroid's mass to hit Earth, Wie said.
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This is no pie-in-the sky dream: The researchers have received two rounds of funding from the NIAC program, and they say their plan is eminently achievable.
"Basically, our proposed concept is an extension of the flight-proven $300 million Deep Impact mission," Wie said, referring to the NASA effort that slammed an impactor into Comet Tempel 1 in 2005.
Demonstration mission coming?
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The HAIV project is still in its early stages, and much more modeling and developmental work is needed. But Wie and his colleagues are ambitious, with plans for a bomb-free flight test in the next decade or so.
"Our ultimate goal is to be able to develop about a $500 million flight demo mission within a 10-year timeframe," Wie said.
The team's current work involves analyzing the feasibility of nuking a small but still dangerous asteroid — one about 330 feet (100 m) wide — with little warning time. However, it wouldn't be too difficult to scale up, Wie said.
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"Once we develop technology to be used in this situation, we are ready to avoid any collision — with much larger size, with much longer warning time," Wie said.