Asteroids harmlessly zip by Earth all the time, but we have some good reasons to worry about asteroid Bennu, which currently has a 1 in 2,700 chance of smacking into our planet in 2135.
There's no need to freak out yet, however. Lawrence Livermore National Laboratory (LLNL), NASA and the National Nuclear Security Administration are on the case, and they're thinking about wielding a big Hammer.
Hammer stands for "Hypervelocity Asteroid Mitigation Mission for Emergency Response," which is an impressive name all on its own. Hammer's a concept at the moment, but if built, it would be a 30-foot-tall (9 meter), 8.8-ton spacecraft that could act as either an asteroid battering ram or as a delivery vehicle for a nuclear device. Let's call it the "nudge or nuke" option.
Bennu is a beast, according to the national lab. It's 1,664 times as heavy as the Titanic and measures more than five football fields in diameter. If it hit Earth, the impact would unleash 80,000 times the energy of the atomic bomb used on Hiroshima in 1945. It would be devastating.
Hammer is designed to launch using NASA's Delta IV Heavy rocket. Researchers at Lawrence Livermore published a paper in the journal Acta Astronautica in February that evaluates the options for using the spacecraft to successfully encourage Bennu to redirect from Earth.
The researchers say ramming the asteroid to change its course would be ideal, but it would need to be a "gentle nudge" that doesn't cause it to break up. It's a complicated proposition.
The team looked at a variety of scenarios. For example, if Earth started launching Hammer missions just 10 years before impact, "it was determined that it could take between 34 and 53 launches of the Delta IV Heavy rocket, each carrying a single Hammer impactor, to make a Bennu-class asteroid miss the Earth," the lab reported on Thursday.
All of this makes it sound like a gentle nudge might not be the best solution for big asteroids.
The lab notes "the findings suggest that the nuclear option may be required with larger objects like Bennu." The researchers are now investigating this approach and plan to release a follow-up study on nuclear scenarios.
LLNL says a nuclear deflection mission would not look like a Hollywood sci-fi film, but would involve detonating a nuclear explosive at a distance from the asteroid to vaporize part of the surface and create a rocket-like propulsion effect to alter its course.
NASA has been working on asteroid deflection plans for some time, notably with the. Hammer, however, would be much bigger and also give the Earth a potential nuclear option.
As 2135 gets closer, we'll get a clearer idea about whether Bennu could actually hit Earth, but it's better to be prepared. Bennu isn't the onlyout there.
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