How to take out an asteroid and save Earth

“Ground truth” information from NASA’s OSIRIS-REx rendezvous could save Earth from a killer asteroid.

Bringing rock samples back from asteroid Bennu on the OSIRIS-REx mission will help computer modelers refine plans for deflecting an asteroid or comet on target for Earth.



NASA scientist warns we’re not prepared for surprise asteroid or comet strike

Asteroid deflection | Los Alamos National LaboratoryWhat would happen if the “big one” were heading towards Earth, like the life-threatening asteroid in the movie Armageddon? Apparently, we are vastly ill-prepared to deal with it.

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NASA scientist warns we're not prepared for surprise asteroid or comet strike

What would happen if the “big one” were heading towards Earth, like the life-threatening asteroid in the movie “Armageddon”? Apparently, we are vastly ill-prepared to deal with it, according to Dr. Joseph Nuth, a prominent researcher with NASA’s Goddard Space Flight Center.

Nuth was speaking at a meeting with nuclear scientists in San Francisco Monday when he made headlines for saying that “the biggest problem, basically, is there’s not a hell of a lot we can do about it at the moment,” when discussing the possibility of a civilization-ending asteroid or comet smashing into the planet, The Guardian reports.

The researcher’s bleak prediction came at the annual meeting of the American Geophysical Union. Nuth noted that, while these kinds of cataclysmic collisions are rare in Earth’s history, they aren’t unprecedented.

“But on the other hand, they are the extinction-level events, things like dinosaur killers, they’re 50 to 60 million years apart, essentially,” The Guardian reports him as saying. “You could say, of course, we’re due, but it’s a random course at that point.”

Nuth noted that our planet had a “close encounter” in 1996 when a comet whirred into Jupiter. Astronomers captured images of another such impact on Jupiter earlier this year. And one of our nearest planetary neighbors experienced a relatively close call in 2014, when a comet came “within spitting distance of Mars.” What makes that especially scary is that the comet was only discovered a mere 22 months before it buzzed the Red Planet.

If that had been Earth, 22 months would would not be nearly enough time to prepare, Nuth stressed.

Nuth said he has suggested that NASA build an “interceptor rocket” that could be stationed at the agency’s new planetary defense office. A ready-to-launch rocket that could be deployed within a year’s notice “could mitigate the possibility of a sneaky asteroid coming in from a place that’s hard to observe, like from the sun,” he said.

Of course, this kind of mission would require Congressional approval, Nuth added; it’s not just something NASA could do on its own.

NASA created a Planetary Defense Coordination Office (PDCO) earlier this year to coordinate efforts to track so-called near-Earth objects — asteroids and comets that could cross into our cosmic neighborhood.

The space agency estimates that it has spotted about 90 percent or more of the near-Earth objects larger than a kilometer in size. These would be the potentially catastrophic objects that science fiction often warns about. Smaller objects still pose a threat as well, and Nuth said Earthlings have to be vigilant about these potential threats.

So, how could we defend against these objects? At the talk, The Guardian reports Dr. Cathy Plesko of the Los Alamos National Laboratory said our options could include deploying “a kinetic impactor” — which she described as “basically a giant cannonball” — or perhaps a nuclear warhead.

But both would come with serious risks, and it would take years of preparation to figure out how to do it right. “We are very carefully doing our homework before finals week,” Plesko said. “We don’t want to be doing our calculations before something is coming. We need to have this work done.”

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Never fear, an oceanic asteroid impact wouldn’t cause apocalyptical tidal waves

Asteroid deflection | Los Alamos National LaboratoryWhen a team of LANL scientists modeled what would happen if an asteroid struck Earth, they discovered a Hollywood-worthy tsunami wouldn’t be the problem. Long-term effects on the climate might. logo

Never fear, an oceanic asteroid impact wouldn't cause apocalyptical tidal waves

But it could have long-term effects on the climate

By Danny Lewis

Fans of apocalyptic disaster movies are probably familiar with the scene: a rogue asteroid spiraling in from outer space lands in the middle of the ocean, triggering massive tidal waves and throwing the world into chaos. But when a group of scientists decided to put this scenario to the test, they found that a real life Deep Impact would have very different results, Maddie Stone reports for Gizmodo.

A team of data scientists at the Los Alamos National Laboratory (LANL) modeled what would happen if an asteroid struck Earth’s vast oceans. They found that while one might expect a giant hunk of space rock to trigger enormous, Hollywood-worthy tsunamis, big waves aren’t the problem to fear.

The waves themselves would likely quickly dissipate out in the ocean. Imagine dropping a rock into a lake—the first ripples might be large, but as they spread out they get smaller and smaller. The same thing would happen in the case of an asteroid or comet impact, Stone reports, but it would still have a larger effect than dropping a pebble into a pond.

But while waves may not be the biggest threat from an asteroid impact, that doesn’t mean it wouldn’t affect our planet.

“The most significant effect of an impact into the ocean is the injection of water vapor into the stratosphere, with possible climate effects,” study leader Galen Gisler said while presenting his results at the American Geophysical Union meeting this week, Stone reports.

An asteroid impact in the ocean could vaporize hundreds of megatons of water, much of which would end up in the atmosphere. While a fair amount of that water vapor would likely turn into rain, some of it could linger slightly higher in what is known as the stratosphere. “And because it’s a potent greenhouse gas, this could have a major effect on our climate,” writes Stone.

Of course, this isn’t the only scenario possible. Many asteroids never make it to the ground, and the water would absorb much of the blast from even a fairly large asteroid exploding, Robinson Meyer reports for The Atlantic.

While that wouldn’t harm human civilization too much, an explosion over a coastal city would be a very different thing. Either way, it might not be a bad idea to figure out ways to stop space rocks before they get too close.

This article originally appeared on

Published Research

Three-dimensional simulations of oblique asteroid impacts into water

By Galen Gisler, Catherine Plesko, et al

Waves generated by impacts into oceans may represent the most significant danger from near-earth asteroids and comets. For impacts near populated shores, the crown splash and subsequent waves, accompanied by sediment lofting and high winds, are more damaging than storm surges from the strongest hurricanes. Asteroids less than 500 m in diameter, impacting deep water far from shores, produce waves that may be detectable over large distances, but are probably not significantly dangerous. We present new three-dimensional simulations of oblique impacts into deep water, with trajectory angles ranging from 27° to 60° (where 90° is vertical). These simulations are performed with the Los Alamos Rage hydrocode, and include atmospheric effects including ablation and airbursts. These oblique impact simulations are specifically performed in order to help determine whether there are additional dangers from the obliquity of impact not covered by previous two-dimensional studies. Water surface elevation profiles, surface pressures, and depth-averaged mass fluxes within the water are prepared for use in propagation studies.


Options and uncertainties in planetary defense: Mission planning and vehicle design response

By Galen Gisler, Catherine Plesko, et al

This paper is part of an integrated study by NASA and the NNSA to quantitatively understand the response timeframe should a threatening Earth-impacting near-Earth object (NEO) be identified. The two realistic responses considered are the use of a spacecraft functioning as either a kinetic impactor or a nuclear explosive carrier to deflect the approaching NEO. The choice depends on the NEO size and mass, the available response time prior to Earth impact, and the various uncertainties. Whenever practical, the kinetic impactor is the preferred approach, but various factors, such as large uncertainties or short available response time, reduce the kinetic impactor’s suitability and, ultimately, eliminate its sufficiency.



How we are going to deflect an asteroid
Crashing a spacecraft into an asteroid could shift its orbital path. The spacecraft DART will be test-crashed on an asteroid, providing insight into future deflection.

Visualization of Threats from Asteroid Ocean Impacts
Here's what would it would look like if an asteroid struck the ocean—and what would happen to the planet as we know it.

OSIRIS-REx, bringing back a bit of an asteroid
The OSIRIS-REx mission will help determine the timeframe within which we must launch a kinetic impactor or a nuclear explosive carrier.

Los Alamos Asteroid Killer
LANL scientists use a supercomputer to model what would happen if we used nuclear energy to deflect an Earth-threatening asteroid.


    Black download iconScientists from Los Alamos National Laboratory are using high performance computing to investigate how an asteroid’s kinetic energy is transferred to the atmosphere and ocean. (Download an animation by astrophysicist Galen Gisler.)

    Black download icon How would the detonation of a nuclear energy source affect an incoming asteroid? 3D supercomputer simulations help address ways to prevent objects in space from colliding with Earth.


    Cathy Plesko  is a computational geophysicist with Los Alamos National Laboratory.

    Cathy Plesko

    Cathy Plesko is a Research Scientist in Applied Physics
    at Los Alamos National Laboratory. She uses the hydrodynamic codes on supercomputers to study what happens when asteroids and comets hit a planet and how to prevent them from hitting Earth.


    Charles Poling, (505) 257-8006,

    Nick Njegomir, (505) 665-9394,