Campaigners are planning an asteroid awareness day and concert on 30 June 2015 to highlight the risks of an impact on Earth. Photograph: Andrzej Puchta/Alamy
Ian Sample, science editor
Wednesday 3 December 2014 06.00 GMT
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Rock stars, astronauts and scientists from around the world have joined forces to combat
the existential threat posed by an asteroid strike with plans for a live concert and an awareness day. [existential - a few days after a hit!]
Preparations for Asteroid Awareness Day will be unveiled alongside
a declaration signed by leading figures that calls on governments, private companies and philanthropists to back technologies that spot and track space rocks that might one day slam into Earth.
Signed by Lord Rees, the astronomer royal, Ed Lu, a former shuttle astronaut, and Brian May of rock group Queen, the declaration calls for a 100-fold speeding up of the search for dangerous asteroids and the adoption of Asteroid Awareness Day on 30 June 2015.
“We are in more danger than has been previously realised,” said May, “In fact it might be said that we are on borrowed time because out of the million or so estimated potential impacting asteroids of sufficient size to cause major destruction on Earth we are probably aware of only 10,000 - about 1 per cent.”
Lu, who visited Mir and the International Space Station, said, “We want to get a groundswell of support from people who understand that this is an issue that’s not only important, but one that we can change.”
“We do, at some point, have to solve this problem. There is a clock ticking on us, we just can’t see the clock. We don’t know when the next major impact is going to happen.”
The awareness day, which may involve a Live Aid-style concert,
coincides with the anniversary of an asteroid strike in 1908 which flattened 2000 sq km of conifer forest in Tunguska in Siberia. The inbound space rock, some 80 metres across, exploded in the air with the force of a large hydrogen bomb.
A strike of that magnitude would destroy London as far out as the M25 ring road. But the damage would not end there. Trains would be derailed across central England; people in Oxford would be thrown into the air and badly burned. Those in Glasgow and Edinburgh would suffer the indignity of having their hats knocked off, according to Bill Napier and David Asher at the Armagh Observatory.
Larger asteroids or comets measuring several kilometres wide will strike Earth every 10m years or so, causing destruction on a global scale. The 200km-wide Chicxulub crater in Mexico was caused by a 10km-wide space rock 68m years ago. The impact sparked a global catastrophe and marked the end of larger dinosaurs.
The most common impacts are smaller space rocks that explode in the air, like the 20 metre-wide meteorite that struck Chelyabinsk in Russia last year.
Larger objects, a few hundred metres across, can cause huge regional damage. The worst – and least frequent – are impacts from bodies 10km and larger. These throw vast amounts of dust into the atmosphere which spread around the globe,
inducing a nuclear winter.
Another danger comes as dust heats up as it falls back to Earth. “That heat pulse can be a problem. It is comparable to being in a pizza oven for an hour,” said Gareth Collins, an asteroid expert at Imperial College, London, who helped develop software to calculate the effects of impacts.
Around a million asteroids in the solar system have the potential to wipe out a city, but so far astronomers’ surveys have found only 1% of these, or around 10,000. The declaration aims to speed up global efforts to find asteroids in the hope that, with sufficient notice, they could be nudged on to a harmless trajectory.
A handful of telescopes are due to join the hunt for Earth-threatening asteroids. The Large Synoptic Survey Telescope (LSST), to be built in Chile, will search for asteroids as small as 100 metres across. Another telescope, called Pan-Starrs (Panoramic Survey Telescope & Rapid Response System) in Hawaii is already in operation. Yet another project in the pipeline, run by Lu, is a space telescope called Sentinel that will search for asteroids as small as 140 metres across.
Scientists have come up with a raft of options to protect Earth from asteroids. One is to fly a massive spacecraft into the body, to nudge its trajectory clear of Earth. Another involves a “gravity tractor”, where a spacecraft flies close to the asteroid and uses its meagre gravitational field to deflect the space rock.
“If we could predict a future massive impact enough time in advance, it would be possible to apply a small nudge to the asteroid in question which would be sufficient to modify its trajectory so it would miss the Earth,” said May who hopes that the initiative will unlock more funds to track and deal with the threat.
The recent Rosetta mission to rendezvous with a comet has taught engineers plenty about how to catch up with a cosmic body, and highlighted how tough the challenge is. “If you want to adopt the Bruce Willis approach, the Rosetta mission is a big wake-up call,” said Collins. “Just landing on a comet was an amazing achievement, but
doing that with astronauts, drilling equipment and nukes is complete fantasy.”
Lord Rees was similarly opposed to nuking asteroids:
“Shattering an asteroid or comet would create fragments on unpredictable orbits that could collectively cause even more damage,” he said.
Lu said that with modern technology, humans have an obligation to protect civilisation. “A hundred years ago, if we got hit by an asteroid, that was just bad luck. We’ve now reached a point where if we get hit by a major asteroid it’s not bad luck, it’s bad planning, or worse, stupidity,” he said.
“An asteroid strike of the kind that wiped out the dinosaurs – more energetic than all the hydrogen bombs in the world exploding simultaneously – is inevitable,” said Richard Dawkins.
“The chance that it will happen in any one person’s lifetime is low but the technology to avert it will take a long time to develop. The right time to start developing it is as soon as we are capable of doing so. And that means now.”
_http://www.theguardian.com/science/2014/dec/03/asteroid-strike-warning-campaigners-day-of-rock-awareness-day
