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| Asteroid 2012 DA14: Can we know about every asteroid? | Asteroid 2012 DA14: Can we know about every asteroid? |
| (about 7 hours later) | |
| By Jason Palmer Science and technology reporter, BBC News | By Jason Palmer Science and technology reporter, BBC News |
| Something to note about asteroid 2012 DA14, due to make an attention-grabbing but harmless pass by the Earth on Friday: its name. | Something to note about asteroid 2012 DA14, due to make an attention-grabbing but harmless pass by the Earth on Friday: its name. |
| Near-Earth objects like these have for a number of years been named starting with the year of their discovery. | Near-Earth objects like these have for a number of years been named starting with the year of their discovery. |
| We only found out about this Olympic-swimming-pool-sized rock kicking around in our cosmic neighbourhood a year ago. | We only found out about this Olympic-swimming-pool-sized rock kicking around in our cosmic neighbourhood a year ago. |
| A month before that, one called 2012 BX34 whizzed by at a distance of 65,000km (41,000mi) - that one had only been discovered two days before. | A month before that, one called 2012 BX34 whizzed by at a distance of 65,000km (41,000mi) - that one had only been discovered two days before. |
| And a few years before that, an 80-tonne space rock called 2008 TC3 ploughed into the Earth's atmosphere, largely burning up and scattering fragments over the Sudan - just 20 hours after it was discovered. | And a few years before that, an 80-tonne space rock called 2008 TC3 ploughed into the Earth's atmosphere, largely burning up and scattering fragments over the Sudan - just 20 hours after it was discovered. |
| In 2009, a fireball attributed to a 10m asteroid lit up the skies over Indonesia, completely unannounced. | In 2009, a fireball attributed to a 10m asteroid lit up the skies over Indonesia, completely unannounced. |
| The list goes on. The point is that astronomers say that we don't know anything about 5 or 10% of the near-Earth asteroids that are larger than 1km in size - 20 times larger than this week's visitor. That's possible civilisation-ending stuff. | The list goes on. The point is that astronomers say that we don't know anything about 5 or 10% of the near-Earth asteroids that are larger than 1km in size - 20 times larger than this week's visitor. That's possible civilisation-ending stuff. |
| "People think that in this day and age we've got this problem covered," said Stephen Lowry of the University of Kent. "We're far from covering this problem." | |
| Below that 1km size, the fraction of as-yet undiscovered objects gets a lot larger. The good news is that below a certain size, depending on what they're made of, some near-Earth asteroids don't pose any danger, breaking up as they pass through the atmosphere. | Below that 1km size, the fraction of as-yet undiscovered objects gets a lot larger. The good news is that below a certain size, depending on what they're made of, some near-Earth asteroids don't pose any danger, breaking up as they pass through the atmosphere. |
| But that leaves a considerable gap. The truth is, even if back in 1908 we had the current array of "surveys" that are constantly scanning the skies, we might well have missed the 100m-wide space rock that devastated a region in Siberia as large as Greater London in Siberia - the Tunguska event. | But that leaves a considerable gap. The truth is, even if back in 1908 we had the current array of "surveys" that are constantly scanning the skies, we might well have missed the 100m-wide space rock that devastated a region in Siberia as large as Greater London in Siberia - the Tunguska event. |
| "The key number is objects around a hundred or a few hundred metres," said Dr Lowry. "Those are the ones we need to be really worried about, and trying to observe the skies more so we can catalogue all of them. But we're quite a way off actually doing that." | "The key number is objects around a hundred or a few hundred metres," said Dr Lowry. "Those are the ones we need to be really worried about, and trying to observe the skies more so we can catalogue all of them. But we're quite a way off actually doing that." |
| Some help is potentially at hand - the dedicated Asteroid Terrestrial-impact Last Alert System or Atlas, designed to give at least a few days' notice of impending asteroids by scanning the whole sky every night. | Some help is potentially at hand - the dedicated Asteroid Terrestrial-impact Last Alert System or Atlas, designed to give at least a few days' notice of impending asteroids by scanning the whole sky every night. |
| And as Alan Fitzsimmons of Queens University Belfast points out, the existing surveys are slowly chipping away at the problem. | And as Alan Fitzsimmons of Queens University Belfast points out, the existing surveys are slowly chipping away at the problem. |
| "We must remember that the surveys that are going on are... doing a fantastic job, as we can tell by the fact that we're now at more than 800 new objects every year...without those we'd know of very few of the more than 9,000 objects we have on our books," he told BBC News. | "We must remember that the surveys that are going on are... doing a fantastic job, as we can tell by the fact that we're now at more than 800 new objects every year...without those we'd know of very few of the more than 9,000 objects we have on our books," he told BBC News. |
| Yet, I ask, couldn't we be taken by surprise in the middle of the night by a completely unknown asteroid? | Yet, I ask, couldn't we be taken by surprise in the middle of the night by a completely unknown asteroid? |
| "Yes we could, and in fact the most likely scenario at the moment is that the next impact will occur with very little warning," he said. | "Yes we could, and in fact the most likely scenario at the moment is that the next impact will occur with very little warning," he said. |
| That, luckily, is pretty unlikely. And any notice at all would help, and thanks in large part to the contribution of amateur asteroid enthusiasts who plot out the precise paths of asteroids spotted by those surveys, we know a lot more about how to mitigate the effects of an eventual impact. | That, luckily, is pretty unlikely. And any notice at all would help, and thanks in large part to the contribution of amateur asteroid enthusiasts who plot out the precise paths of asteroids spotted by those surveys, we know a lot more about how to mitigate the effects of an eventual impact. |
| Prof Fitzsimmons recalled the situation with 2008 TC3, which hit less than a day after it was discovered. | Prof Fitzsimmons recalled the situation with 2008 TC3, which hit less than a day after it was discovered. |
| "Although we couldn't do anything in terms of deflecting it - and didn't need to, it was only a few metres across - within a few hours the impact point and the exact time of impact were known incredibly accurately. | "Although we couldn't do anything in terms of deflecting it - and didn't need to, it was only a few metres across - within a few hours the impact point and the exact time of impact were known incredibly accurately. |
| "What that did show us is that if we did spot one of these object on an impact trajectory, we do have the capability to assess its risk." | "What that did show us is that if we did spot one of these object on an impact trajectory, we do have the capability to assess its risk." |
| As Dr Lowry puts it, however, an eventual impact scenario, even if we know ahead of time, is inescapable. | As Dr Lowry puts it, however, an eventual impact scenario, even if we know ahead of time, is inescapable. |
| "It is a mathematical certainty that one of these objects will hit at some point in the future - asteroids have been hitting Earth throughout its history, and we're fairly sure major impacts have been responsible for one major extinction," he said. | "It is a mathematical certainty that one of these objects will hit at some point in the future - asteroids have been hitting Earth throughout its history, and we're fairly sure major impacts have been responsible for one major extinction," he said. |
| "Mankind has always had this gun pointed at its head; we're just lucky we're in a time when we have the technological capability to search for these things and try and develop a way of dealing with them. | "Mankind has always had this gun pointed at its head; we're just lucky we're in a time when we have the technological capability to search for these things and try and develop a way of dealing with them. |
| "But don't lose any sleep about it." | "But don't lose any sleep about it." |