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How to Target an Asteroid
Wednesday, April 17, 2013 8:06
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Like many of his colleagues at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., Shyam Bhaskaran is working a lot with asteroids these days. And also like many of his colleagues, the deep space navigator devotes a great deal of time to crafting, and contemplating, computer-generated 3-D models of these intriguing nomads of the solar system.
But while many of his coworkers are calculating asteroids’ past, present and future locations in the cosmos, zapping them with the world’s most massive radar dishes, or considering how to rendezvous and perhaps even gently nudge an asteroid into lunar orbit, Bhaskaran thinks about how to collide with one.
“If you want to see below the surface of an asteroid, there’s no better way than smacking it hard,” said Bhaskaran. “But it’s not that easy. Hitting an asteroid with a spacecraft traveling at hypervelocity is like shooting an arrow at a target on a speeding race car.”
The term hypervelocity usually refers to something traveling at very high speed — two miles per second (6,700 mph / 11,000 kilometers per hour) or above. Bhaskaran’s hypothetical impacts tend to be well above
“Most of the hypervelocity impact scenarios that I simulate have spacecraft/asteroid closure rates of around eight miles a second, 30,000 miles per hour [about 48,000 kilometers per hour],” said Bhaskaran.
In the majority of our solar system, where yield signs and “right of way” statutes have yet to find widespread support, hypervelocity impacts between objects happen all the time. But all that primordial violence usually goes unnoticed here on Earth, and almost never receives scientific scrutiny.
“High-speed impacts on asteroids can tell you so many things that we want to know about asteroids,” said Steve Chesley, a near-Earth object scientist at JPL. “They can tell you about their composition and their structural integrity — which is how they hold themselves together. These are things that are not only vital for scientific research on the origins of the solar system, but also for mission designers working on ways to potentially move asteroids, either for exploitation purposes or because they may be hazardous to Earth.”
Hypervelocity impacts by spacecraft are not just a hypothetical exercise. Scientists have taken the opportunity to analyze data from used spacecraft and rocket stages that have impacted the moon and other celestial bodies since the Apollo program. On July 4, 2005, NASA’s Deep Impact spacecraft successfully collided its dynamic impactor with comet 9P/Tempel 1 — it was the first hypervelocity impact of a primitive solar system body.
More information about asteroids and near-Earth objects is at: http://www.jpl.nasa.gov/asteroidwatch , and on Twitter: @asteroidwatch .
