NASA Admits It May Not Be Able To Stop Bennu Asteroid From Destroying Earth

Friday, 16 March 2018 - 11:34AM
Technology
Space
NASA
Friday, 16 March 2018 - 11:34AM
NASA Admits It May Not Be Able To Stop Bennu Asteroid From Destroying Earth
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Image Credit: Pixabay
Earlier this month, we reported on NASA's new plan to deflect the asteroid Bennu, which involves a new spacecraft called the HAMMER. The idea is that we can knock Bennu off-course by ramming it with HAMMER, which will rely on its 8.8-ton mass to create a powerful impact.

For context, Bennu is: roughly the size of the Empire State Building, weighs about 1,600 times more than the Titanic, and would cause an impact 80,000 times more powerful than the Hiroshima bomb if it hit Earth.



If that doesn't work, then the HAMMER can be equipped with a nuclear bomb to help give it more "oomph." Unfortunately, according to new research from the Lawrence Livermore National Laboratory, there are some problems with this plan.

First, we need to be sure that it makes sense to send out HAMMER to deflect Bennu at all. According to Kirsten Howley, a physicist at the Laboratory, "The push you need to give it is very small if you deflect the asteroid 50 years out. But that far out, you're likely to think the percentage of being hit would be 1 percent. The probability of a Bennu impact might be 1 in 2,700 today, but that will almost certainly change – for better or worse – as we gather more data about its orbit."

For clarity's sake, "1 in 2,700" is a 0.00037037037% chance. If that number stays the same, no problem. But if that probability increases, one HAMMER won't be enough to stop Bennu.

As it stands, it would take 7.4 years to ram a HAMMER into Bennu – including time to plan the mission, build the craft in the first place, and fly it into the asteroid. From there, it would take several more years for the asteroid to actually change course... Meaning that time is not on our side. The LLNL researched potential timelines and found that we'd need to launch seven to eleven HAMMERs if we waited until the impact was 25 years away. But that's not the whole picture according to Megan Bruck Syal, another physicist at the Laboratory:
 
"When many launches are required for a successful deflection, the mission success becomes more difficult, due to the failure rate associated with each individual launch. If we only had 10 years from launch, we would need to hit Bennu with hundreds of tons of HAMMER mass just to barely deflect it off of an Earth-impacting path, requiring dozens of successful launches and impact at the asteroid."

Of course, this doesn't take the nuclear option into account – which may become our only hope if the kinetic impactor method fails. We also have the giant, asteroid-destroying laser beam Russian scientists are working on, but who knows if it could stop a monster like Bennu?

Only time will tell.
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