Asteroid

Death by asteroid may come in unexpected ways

asteroid breakup
asteroid breakup

Every now and then a really big rock from space comes careening through Earth’s atmosphere. Depending on its size, angle of approach and where it lands, few people may notice — or millions could face a risk of imminent death.

Concern about these occasional, but potentially catastrophic, events keeps some astronomers scanning the skies. Using all types of technologies, they’re scouting for a killer asteroid, one that could snuff out life in a brief but dramatic cataclysm. They’re also looking for ways to potentially deter an incoming biggie from an earthboard path.

But if a big space rock were to make it to Earth’s surface, what could people expect? That’s a question planetary scientists have been asking themselves — and their computers. And some of their latest answers might surprise you.

For instance, it’s not likely a tsunami will take you out. Nor an earthquake. Few would need to even worry about being vaporized by the friction-heated space rock. No, gusting winds and shock waves set off by falling and exploding space rocks would claim the most lives. That’s one of the conclusions of a new computer model.

It investigated the likely outcomes of more than a million possible asteroid impacts. In one extreme case, a space rock 200 meters (660 feet) wide whizzes 20 kilometers (12 miles) per second into London, England. This smashup would kill more than 8.7 million people, computers estimate. And nearly three-quarters of those expected to die in that doomsday scenario would lose their lives to winds and shock waves.

Clemens Rumpf and his colleagues reported this online March 27 in Meteoritics & Planetary Science. Rumpf is a planetary scientist in England at the University of Southampton.

In a second report, Rumpf’s group looked at 1.2 million potential smashups. Here, the asteroids could be up to 400 meters (1,300 feet) across. Again, winds and shock waves were the big killers. They’d account for about six in every 10 deaths across the spectrum of asteroid sizes, the computer simulations showed.

Many previous studies had suggested tsunamis would be the top killer. But in these analyses, those killer waves claimed only around one in every five of the lives lost.

Even asteroids that explode before reaching Earth’s surface can generate high-speed wind gusts, shock waves of pressure in the atmosphere and intense heat. Space rocks big enough to survive the descent pose far greater risks. They can spawn earthquakes, tsunamis, flying debris — and, of course, gaping craters.

“These asteroids aren’t an everyday concern,” Rumpf observes. Yet clearly, he notes, the risks they pose “can be severe.” His team describes just how severe they could be in a paper posted online April 19 in Geophysical Research Letters.

Previous studies typically considered individually each possible effect of an asteroid impact. Rumpf’s group instead looked at them collectively. Quantifying the estimated hazard posed by each effect, says Steve Chesley, might one day help some leaders make one of the hardest calls imaginable — work to deflect an asteroid or just let it hit. Chesley is a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. (NASA stands for National Aeronautics and Space Administration.) Chesley was not involved with either of the new studies.

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asteroid Earth
Computer simulations reveal that most of the deaths caused by an earthbound asteroid (illustrated) would come from gusting winds and shock waves.

Land hits would pose the biggest risks

The 1.2 million simulated asteroid impacts each fell into one of 50,000 scenarios. They varied in location, speed and angle of strike. Each scenario was run for 24 different asteroids. Their diameters ranged from 15 to 400 meters (50 to 1,300 feet). About 71 percent of the Earth is covered by water, so the simulations let asteroids descend over water in nearly 36,000 of the scenarios (about 72 percent).

The researchers began with a map of human…

Here’s how an asteroid impact would kill you

asteroid hitting Earth
DEATH FROM THE SKIES Computer simulations reveal that most of the lethality of an earthbound asteroid (illustrated) comes from gusting winds and shock waves.

It won’t be a tsunami. Nor an earthquake. Not even the crushing impact of the space rock. No, if an asteroid kills you, gusting winds and shock waves from falling and exploding space rocks will most likely be to blame. That’s one of the conclusions of a recent computer simulation effort that investigated the fatality risks of more than a million possible asteroid impacts.

In one extreme scenario, a simulated 200-meter-wide space rock whizzing 20 kilometers per second whacked London, killing more than 8.7 million people. Nearly three-quarters of that doomsday scenario’s lethality came from winds and shock waves, planetary scientist Clemens Rumpf and colleagues report online March 27 in Meteoritics & Planetary Science.

In a separate report, the researchers looked at 1.2 million potential impactors up to 400 meters across striking around the globe. Winds and shock waves caused about 60 percent of the total deaths from all the asteroids, the team’s simulations showed. Impact-generated tsunamis, which many previous studies suggested would be the top killer, accounted for only around one-fifth of the deaths, Rumpf and colleagues report online April 19 in Geophysical Research Letters.

“These asteroids aren’t an everyday concern, but the consequences can be severe,” says Rumpf, of the University of Southampton in England. Even asteroids that explode before reaching Earth’s surface can generate high-speed wind gusts, shock waves of pressure in the atmosphere and intense heat. Those rocks big enough to survive the descent pose even more hazards, spawning earthquakes, tsunamis, flying debris and, of course, gaping craters.

While previous studies typically considered each of these mechanisms individually, Rumpf and colleagues assembled the first assessment of the relative deadliness of the various effects of such impacts. The estimated hazard posed by each effect could one day help leaders make one of the hardest calls imaginable: whether to deflect an asteroid or let it hit, says Steve Chesley, a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who was not involved with either study.

The 1.2 million simulated impactors each fell into one of 50,000 scenarios, which varied in location, speed and angle of strike. Each scenario was run with 24 different asteroid sizes,…

Look Up! A Huge Asteroid Is Whizzing Past Earth This Week

Grab your telescope and get ready to duck, because an enormous space rock will be zooming through the sky the night of April 19.

Okay, fine. You won’t actually need to duck. The path of asteroid 2014 JO25 will be a near miss in space terms only, arriving in the sky 1.1 million miles from where we stand. That’s about four and a half trips to the Moon.

While it may not be the most dramatic flyby, 2014 JO25’s appearance is worth celebrating. Discovered just…