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Headlines Published on 17 April 2009

Title Keeping track of asteroids gets easier

The identification of meteorites has never been easy. But an international group of researchers recently successfully identified an asteroid in space before it entered the Earth's atmosphere. With the use of computers, researchers can now find out what part of the solar system the asteroid came from and predict the time of entry as well as the site where its shattered remaining parts lie. The results of the study were published in the journal Nature.

A meteorite found in the Nubian Desert, Sudan © NASA/SETI
A meteorite found in the Nubian Desert, Sudan

Team member Dr Mark Boslough from the Sandia National Laboratories in the US said the research shows the astronomers' 'ability to discover and predict the impact of a space object'. He went on to say that the work also tested how quickly a society can respond to a predicted impact.

'In this case, it was never a threat, so the response was scientific,' he explained. 'Had it been deemed a threat a larger asteroid that would explode over a populated area an alert could have been issued in time that could potentially save lives by evacuating the danger zone or instructing people to take over.'

The information collected through this research can contribute to the astronomers' quest to study the orbits of parent bodies that generate the different meteorites found on Earth. According to Dr Boslough, future space missions aiming to explore or mine the asteroids in 'Earth-crossing orbits' would benefit from this latest discovery.

The asteroid assessed in this study, '2008 TC3', was initially sighted by the NASA-sponsored Catalina Sky Survey telescope at the Arizona-based Mount Lemmon last October. Several observatories that were alerted to the four-metre-diameter asteroid about the size of a car then imaged the object.

Scientists and astronomers worldwide tracked and scanned TC3 for 20 hours before its demise. The asteroid had a velocity of about 44 579 kilometres per hour when it entered the atmosphere, and it created a fiery trail 82 km long before exploding about 36 880 metres from the ground, the team said.

Researchers from NASA's Near Earth Object Program said in a statement: 'A spectacular fireball lit up the pre-dawn sky above northern Sudan on 7 October 2008.'

The calculations of where the meteorite would touch ground were right on the money. The scientists had predicted the meteorite would impact the ground in the Nubian Desert of northern Sudan 19 hours after discovery.

The scientists then used a map to find the meteorite fragments. The Jet Propulsion Laboratory (JPL) of NASA gave the recovery team a chart with information on where to search.

Key members of the team were the JPL's Dr Steve Chesley, Dr Peter Jenniskens, a meteor astronomer with the SETI Institute in the US, and Professor Muawia Shaddad of the University of Khartoum in Sudan.

'My work usually begins and ends with trajectories of objects in space,' commented Dr Chesley. 'We had accurately predicted when and where TC3 would enter over the Sudan. '[Dr] Jenniskens was asking for a map of where any surviving fireball fragments could have landed. That was a first for the Near-Earth Object Program Office.'

Following a 3-day search, the researchers recovered 15 samples with a combined mass of 1.24 pounds (0.54 kilogrammes). The fragments, according to the team, were black, porous, rocky and rounded. On two other trips, Dr Jenniskens and Professor Khartoum collected 280 meterorites with a combined mass of almost 5 kilogrammes.

For his part, Dr Boslough said: 'In this post-rational age where scientific explanations and computer models are often derided as "only theories", it is nice to have a demonstration like this.'

Other participants of this study include universities from Canada, the Czech Republic, Ireland, the Netherlands and the UK, as well as the NASA Johnson Space Center in the US.

More information:

  • Sandia
  • Near Earth Object Program
  • 'ESA deals with dangerous natural space debris'

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