Post by Deleted on Dec 1, 2012 14:49:44 GMT
From the print edition of The Economist, by Benjamin Sutherland
Humans will ponder fate as an asteroid just misses them
Towards the end of 2013, with any luck, Comet ISON will light up the night sky-and even, possibly, the daytime sky-as it screeches round the sun and back out to the outer reaches of the solar system, its tail streaming out ahead of it. But it is an earlier heavenly encounter, far less spectacular but much, much closer, that is enthralling the small band of space scientists interested in keeping the Earth safe.
On the evening of February 15th an asteroid called 2012 DA 14 will pass so close to the Earth that, although it is only the length of an Olympic swimming pool, it will be visible through good binoculars. Never has the orbit of a rock that big been calculated to pass so near: 2012 DAl4will be flying lower than the satellites which beam down television programmes. Were it on a trajectory that actually hit the Earth, its speed of nearly 13km (8 miles) a second would generate a detonation-on or above the ground, depending on the rock's exact size and composition-that could flatten an area the size of Greater London.
Somewhat worryingly, no one even noticed the asteroid during its previous close approach in February 2012. It was only discovered with a dash of luck by Spain's La Sagra Observatory after receding from Earth for a week to a distance of 4.3m kilometres. The observatory's "mediocre means" would have missed it were it not for a $7,695 grant to buy a better camera for the telescope in 2010, says Jaime Nomen, an astronomer there.
The fly-by in 2013 will be a boon for several reasons, says Andrea Milani Comparetti, head of NeoDyS, a team at Italy's University of Pisa that calculates asteroid trajectories. First, it will enable astronomers to calculate more precisely the slim odds that 2012 DA 14 will smash into Earth the next time it comes close, in 2026. Data available today suggest a one-in-27,000 chance of a collision in 2026. More precise measurements will probably reveal a future impact to be even less likely. But if 2012 DA 14 passes through a roughly 500-metre-wide "keyhole" strip of space that happens to be about 28,100km from Earth, gravity could tug its orbit just enough for it to hit the Earth 13 years later on February 13th, a Friday. In that event, a spacecraft would surely be scrambled to nudge the rock back into a harmless orbit.
Secondly, the fly-by will help scientists determine if 2012 DA 14 is made of dry silicate rock, like most asteroids, or of something more interesting, such as minerals that might be mined for water and rocket fuel. Finding such things on near-Earth asteroids could make space exploration a lot easier, since the costs of lifting water and fuel from the Earth remain stubbornly high.
A third benefit will be money: the approach of 2012 DA 14 is boosting funding for planet defense, says Bill Nye, executive officer of the Planetary Society, an American charity that has awarded about $250,000 to 33 "primarily hard-core amateur" asteroid hunters, La Sagra among them. Such efforts are important, says Ed Lu, who, as a NASA astronaut on the International Space Station for 206 days, saw the streaks of flame as small space rocks burned up below him in the atmosphere.
Mr Lu is now chairman of the B612 Foundation, an American non-profit organisation which is seeking donations to build an asteroid spotting orbiting telescope called Sentinel. He hopes the close encounter will energise fund-raising. While comet ISON may thrill the crowds, 2012 DA14 will be a reminder that the solar system offers more than spectacle: humanity is still subject to cosmic fate, and needs to keep its eyes open.
Humans will ponder fate as an asteroid just misses them
Towards the end of 2013, with any luck, Comet ISON will light up the night sky-and even, possibly, the daytime sky-as it screeches round the sun and back out to the outer reaches of the solar system, its tail streaming out ahead of it. But it is an earlier heavenly encounter, far less spectacular but much, much closer, that is enthralling the small band of space scientists interested in keeping the Earth safe.
On the evening of February 15th an asteroid called 2012 DA 14 will pass so close to the Earth that, although it is only the length of an Olympic swimming pool, it will be visible through good binoculars. Never has the orbit of a rock that big been calculated to pass so near: 2012 DAl4will be flying lower than the satellites which beam down television programmes. Were it on a trajectory that actually hit the Earth, its speed of nearly 13km (8 miles) a second would generate a detonation-on or above the ground, depending on the rock's exact size and composition-that could flatten an area the size of Greater London.
Somewhat worryingly, no one even noticed the asteroid during its previous close approach in February 2012. It was only discovered with a dash of luck by Spain's La Sagra Observatory after receding from Earth for a week to a distance of 4.3m kilometres. The observatory's "mediocre means" would have missed it were it not for a $7,695 grant to buy a better camera for the telescope in 2010, says Jaime Nomen, an astronomer there.
The fly-by in 2013 will be a boon for several reasons, says Andrea Milani Comparetti, head of NeoDyS, a team at Italy's University of Pisa that calculates asteroid trajectories. First, it will enable astronomers to calculate more precisely the slim odds that 2012 DA 14 will smash into Earth the next time it comes close, in 2026. Data available today suggest a one-in-27,000 chance of a collision in 2026. More precise measurements will probably reveal a future impact to be even less likely. But if 2012 DA 14 passes through a roughly 500-metre-wide "keyhole" strip of space that happens to be about 28,100km from Earth, gravity could tug its orbit just enough for it to hit the Earth 13 years later on February 13th, a Friday. In that event, a spacecraft would surely be scrambled to nudge the rock back into a harmless orbit.
Secondly, the fly-by will help scientists determine if 2012 DA 14 is made of dry silicate rock, like most asteroids, or of something more interesting, such as minerals that might be mined for water and rocket fuel. Finding such things on near-Earth asteroids could make space exploration a lot easier, since the costs of lifting water and fuel from the Earth remain stubbornly high.
A third benefit will be money: the approach of 2012 DA 14 is boosting funding for planet defense, says Bill Nye, executive officer of the Planetary Society, an American charity that has awarded about $250,000 to 33 "primarily hard-core amateur" asteroid hunters, La Sagra among them. Such efforts are important, says Ed Lu, who, as a NASA astronaut on the International Space Station for 206 days, saw the streaks of flame as small space rocks burned up below him in the atmosphere.
Mr Lu is now chairman of the B612 Foundation, an American non-profit organisation which is seeking donations to build an asteroid spotting orbiting telescope called Sentinel. He hopes the close encounter will energise fund-raising. While comet ISON may thrill the crowds, 2012 DA14 will be a reminder that the solar system offers more than spectacle: humanity is still subject to cosmic fate, and needs to keep its eyes open.