Skip to main content

Don't count 'doomsday asteroid' out yet

By Greg Bear, Special to CNN
January 24, 2013 -- Updated 1346 GMT (2146 HKT)
The March 1966 cover of Analog Science Fiction/Science Fact featured an illustration of an asteroid hitting Earth. J.E. Enever published his ground-breaking article,
The March 1966 cover of Analog Science Fiction/Science Fact featured an illustration of an asteroid hitting Earth. J.E. Enever published his ground-breaking article, "Giant Meteor Impact," in this issue, detailing what such strikes could do, and have done, to the Earth, with vivid prose and terrifying physics.
STORY HIGHLIGHTS
  • Greg Bear: Asteroid Apophis flew by this month and was much larger than expected
  • Named after an evil Egyptian serpent god, Apophis swings by every seven years
  • Bear: We can never be 100% sure how close it will come or if events might change its course
  • If Apophis hit Earth, he says, the blast would be the equivalent of over a billion tons of TNT

Editor's note: Greg Bear is an internationally bestselling science-fiction author of many books, including "Moving Mars," "Darwin's Radio" and "Hull Zero Three." As a freelance journalist, he covered 10 years of the Voyager missions at the Jet Propulsion Laboratory.

(CNN) -- Look up at our nearest neighbor, the moon, and you'll see stark evidence of the dangerous neighborhood we live in. The Man in the Moon was sculpted by large-scale events, including many meteor and asteroid impacts.

In 1994, the comet Shoemaker-Levy 9 dove into Jupiter. The result was awesome. The impact caused a brilliant flash, visible in Earth telescopes, and left an ugly dark scar on Jupiter's cold, gaseous surface.

Greg Bear
Greg Bear

With the recent fly-by of a 1,000-foot-wide asteroid labeled 99942 Apophis, one of a class of space rocks referred to as "near-Earth objects" or "Earth-grazers," scientists have revised their worst estimates of its chances of striking Earth. Current thinking is: We're safe. For the next couple of decades.

But this does not mean the danger is over. Far from it.

Become a fan of CNNOpinion
Stay up to date on the latest opinion, analysis and conversations through social media. Join us at Facebook/CNNOpinion and follow us @CNNOpinion on Twitter. We welcome your ideas and comments.



Named after the evil Egyptian serpent god Apophis, lord of chaos and darkness -- and recently dubbed the "doomsday asteroid" -- it flies past Earth every seven years. This year, its 1,000-foot bulk approached to within 9 million miles. In 2029, it will swoop in close enough to put some of our orbiting satellites in peril -- 20,000 miles. In that year, no doubt Apophis will arouse even more attention, because it will be visible in the daytime sky. In 2036, it will probably pass by at a reassuring 14 million miles.

Yet there's always a possibility we don't have these measurements exactly right. Something could happen at any point in Apophis' orbit to modify its course, just a smidgen. A tiny collision with another object, way out beyond Mars? What could change between now and 2029, or during any orbit thereafter?

Apophis masses at more than 20 million tons. If it hit Earth, the impact would unleash a blast the equivalent of over a billion tons of TNT. That's not an extinction event, but it could easily cause billions of deaths and months, if not years, of climate disruption.

The potential risk is huge. And Apophis is far from alone. Life in our solar system has always been dangerous. As kids we learn about the Barringer Crater in Arizona, a relatively recent formation -- 50,000 years old -- caused by a rock weighing several times more an aircraft carrier. That impact released the equivalent of 20 megatons of TNT and left a crater 4,000 feet wide.

Both Mars and Earth were long ago hit by planet-sized objects, one spinning off our Moon, the other shaping two distinctly different hemispheres on Mars. To this day, a steady rain of meteors falls on Earth -- some of them left-over pebbles and dust from worn-out comets, others from the "asteroid belt," still others from big strikes on the Moon and Mars.

Asteroid to fly between Earth, moon
Debunking doomsday: Killer asteroid
The Number: hazardous asteroids
The Number: hazardous asteroids

Since oceans cover two-thirds of the Earth's surface, it's more likely debris will hit water than land. Scientists believe it was the blast of a 6-mile-wide asteroid off the coast of Mexico some 64 million years ago that changed Earth's weather for years and hastened the departure of the dinosaurs. Ocean hits are worse than land hits, not just because of immense tidal waves, but because of the vast quantities of super-heated water vapor and dust that spread from the impact to shroud the entire Earth.

In March 1966, J.E. Enever published his ground-breaking article, "Giant Meteor Impact," in the periodical Analog Science Fiction/Science Fact. Enever surveyed the available material on meteor and asteroid strikes, then published his own calculations and analysis of what such strikes could do, and have done, to the Earth, with cinematically vivid prose and equally terrifying physics.

He was the first to put it all together and publish in a respected and widely available forum. Although geology was still reluctant to admit to any form of "catastrophism," eschewing biblical explanations, many read and pondered ... seriously.

In the decades since Enever's article, writers, scientists, and engineers have proposed various ways to avert such disasters. Some have suggested we strap rocket motors to a threatening rock and nudge it away. A steady pulse of projectile "paintballs" could also do the trick.

Others have suggested we use nuclear weapons to "kick" an asteroid from its orbit, or even to shatter it into smaller debris -- a rather dim idea that misleads us into believing a single bullet is worse than the blast from a shotgun. Our atmosphere provides little protection against meteors larger than a truck.

Moreover, many asteroids are chunky masses of rock and dust loosely held together by very little gravity, like loosely packed peanut clusters. Attempting to attach a rocket to one of these might merely dislodge a few "peanuts," leaving the rest to do the dirty work.

Wrap one of these peanut clusters in a giant steel net, then drag it off its deadly course? Intriguing, but for now -- like deploying tractor beams from the starship Enterprise -- it's just so much super-science.

Follow @CNNOpinion on Twitter.

Join us at Facebook/CNNOpinion.

The opinions expressed in this commentary are solely those of Greg Bear.

ADVERTISEMENT
Part of complete coverage on
July 11, 2014 -- Updated 1315 GMT (2115 HKT)
Michael Werz says in light of the spying cases, U.S. is seen as a paranoid society that can't tell friends from foes.
July 11, 2014 -- Updated 1317 GMT (2117 HKT)
Eric Liu explains why in his new book, he calls himself "Chinese American" -- without a hyphen.
July 11, 2014 -- Updated 1512 GMT (2312 HKT)
John Bare says hands-on learning can make a difference in motivating students to acquire STEM skills.
July 11, 2014 -- Updated 1320 GMT (2120 HKT)
Karl Alexander and Linda Olson find blacks and whites live in urban poverty with similar backgrounds, but white privilege wins out as they grow older.
July 10, 2014 -- Updated 1620 GMT (0020 HKT)
Frida Ghitis says a poll of 14 Muslim-majority nations show people are increasingly opposed to extremism.
July 10, 2014 -- Updated 1828 GMT (0228 HKT)
Ruben Navarrette says spending more on immigation enforcement isn't going to stop the flow of people seeking refuge in the U.S.
July 10, 2014 -- Updated 2048 GMT (0448 HKT)
Faisal Gill had top security clearance and worked for the Department of Homeland Security. That's why it was a complete shock to learn the NSA had him under surveillance.
July 10, 2014 -- Updated 1841 GMT (0241 HKT)
Kevin Sabet says the scientific verdict is that marijuana can be dangerous, and Colorado should be a warning to states contemplating legalizing pot.
July 9, 2014 -- Updated 2047 GMT (0447 HKT)
World War I ushered in an era of chemical weapons use that inflicted agonizing injury and death. Its lethal legacy lingers into conflicts today, Paul Schulte says
July 10, 2014 -- Updated 1137 GMT (1937 HKT)
Tom Foley and Ben Zimmer say Detroit's recent bankruptcy draws attention to a festering problem in America -- cities big and small are failing to keep up with change.
July 10, 2014 -- Updated 1201 GMT (2001 HKT)
Mel Robbins says many people think there's "something suspicious" about Leanna Harris. But there are other interpretations of her behavior
July 9, 2014 -- Updated 1753 GMT (0153 HKT)
Amy Bass says Germany's rout of Brazil on its home turf was brutal, but in defeat the Brazilian fans' respect for the victors showed why soccer is called 'the beautiful game'
July 9, 2014 -- Updated 2107 GMT (0507 HKT)
Aaron Carroll explains how vaccines can prevent illnesses like measles, which are on the rise
July 9, 2014 -- Updated 0008 GMT (0808 HKT)
Aaron Miller says if you think the ongoing escalation between Israel and Hamas over Gaza will force a moment of truth, better think again
July 8, 2014 -- Updated 1903 GMT (0303 HKT)
Norman Matloff says a secret wage theft pact between Google, Apple and others highlights ethics problems in Silicon Valley.
July 8, 2014 -- Updated 2237 GMT (0637 HKT)
The mother of murdered Palestinian teenager Mohammed Abu Khder cries as she meets Palestinian president Mahmoud Abbas in Ramallah, West Bank on July 7, 2014.
Naseem Tuffaha says the killing of Israeli teenagers has rightly brought the world's condemnation, but Palestinian victims like his cousin's slain son have been largely reduced to faceless, nameless statistics.
ADVERTISEMENT