Science & Technology

The HAMMER Spacecraft Could Save the World from Killer Asteroids

Space is a shooting gallery, with rocks (also known as asteroids) flying in between the planets — and sometimes dangerously close to Earth. If a killer asteroid comes towards our planet, scientists have a new plan to push it on a different path. And this plan doesn't involve somebody like Armageddon's crew of oil drillers. Instead, it relies on an impressively named spacecraft. It's hammer time.

Bashing into Bennu

A spacecraft concept called HAMMER (Hypervelocity Asteroid Mitigation Mission for Emergency Response vehicle) could be dispatched to nudge rogue space rocks out of the way. HAMMER's possible mission is to deflect asteroid 101955 Bennu, which is also the target of an upcoming NASA survey mission called OSIRIS-REx.

Bennu might slam into Earth on September 25, 2135. While the chances are slight (just 1 in 2,700), the impact would wreak devastation. Its kinetic energy would be roughly 80,000 times the energy of the Hiroshima bomb that exploded over Japan in 1945.

"The chance of an impact appears slim now, but the consequences would be dire," said Kirsten Howley, a co-author of a new paper on HAMMER that recently appeared in Acta Astronautica, in a statement. "The ultimate goal is to be ready to protect life on Earth," added Howley, who is also a physicist at the Lawrence Livermore National Laboratory in California.

HAMMER would slam a device called a kinetic impactor into Bennu, which would alter the asteroid's path in space. The trick is, it would take several blows to work effectively. Even if scientists planned 25 years ahead of the impact, it would take at least seven HAMMER spacecraft to deliver enough energy, the scientists said.

Researchers also outlined a more extreme option where they detonate a nuclear bomb in space, nearby Bennu. The goal isn't a Hollywood-like explosion, though. Instead, X-rays from the explosion would wash over Bennu's surface and vaporize the top layer. The vaporization would give Bennu a kick, just like a rocket, and the asteroid would be pushed into a new orbit away from Earth.

The 8.8-ton conceptual HAMMER spacecraft (right) is designed to fit within the Delta IV Heavy, the world’s second highest-capacity launch vehicle in operation, surpassed only by SpaceX’s Falcon Heavy rocket.

Planetary Protection Watchers

But before you lose any sleep, rest assured that NASA is always scanning the skies. Their network's telescopes regularly look at Bennu with radar to evaluate its threat. They are on the hunt for other dangerous space rocks, too. NASA-funded telescopes tirelessly search for asteroids, especially for any nearby ones that are larger than 460 feet (140 meters) wide. Asteroids of this size would cause widespread devastation if they slam into water or land.

NASA keeps looking, but so far it's good news for Earth: they found no Armageddon-like asteroid that will slam into Earth, with 100 percent probability. You can see the results for yourself at the agency's Small Body Database Browser. Unfortunately, NASA's network isn't optimized to find smaller asteroids, so from time to time, one will skirt through the agency's safety net. If you're upset about that, it might be time to ask for more NASA funding.

The HAMMER study was led by Brent Barbee, an aerospace engineer at NASA's Goddard Space Flight Center. This paper is part of a multi-agency collaboration to protect the Earth from asteroids. The agency team plans more case studies soon. Future papers will look at Didymos B (a candidate for asteroid deflection missions), as well as a smaller version of Comet Churyumov-Gerasimenko (the target of the European Space Agency's Rosetta mission, which ended in 2016).

NASA's Plan to Save Earth from a Giant Asteroid

Written by Elizabeth Howell April 20, 2018

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