Research led by a Kent-based space scientist has uncovered new evidence of meteor particles reaching the Antarctic ice sheet 430,000 years ago.
The findings highlight the importance of reassessing the threat of medium-sized asteroids, with the potential for “destructive” consequences, the team said.
Researchers recovered extra-terrestrial particles on the summit of Walnumfjellet within the Sør Rondane Mountains in east Antarctica. The discovery indicated a so-called low-altitude meteoritic touchdown event – where a jet of melted and vaporised material from an asteroid at least 100 metres in size reached the surface at high velocity.
The research, published in the Science Advances journal, said finding evidence of such events “remains critical to understanding the impact history of Earth and estimating hazardous effects of asteroid impacts”.
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Dr van Ginneke said while it is “highly unlikely” that such an event would happen over a densely-populated area – with less than 1 per cent of the surface of the earth considered densely populated – its effects can be widespread.
“Severe effects of such an impact can be felt over hundreds of kilometres,” he said. “Therefore, even if such an impact were to occur hundreds of kilometres away from a densely populated area, the amount of devastation would not be negligible and would need to be taken into account.”
Dr van Ginneken said the study could help improve knowledge of the rate of such impacts in the past and therefore how often these might happen in the future.
The paper states: “These events are potentially entirely destructive over a large area, corresponding to the area of interaction between the hot jet and the ground.
“Touchdown events may not threaten human activity, apart from the formation of a large plume and the injection of ice crystals and impact dust in the upper atmosphere, if these occur over Antarctica.
“However, if a touchdown impact event takes place above a densely-populated area, this would result in millions of casualties and severe damage over distances of up to hundreds of kilometres.”
Reader Q&A: How can we tell that a meteorite has come from a particular planet?
Asked by: Rodney Minns, Liphook, Hampshire
Rocks, including meteorites, can be dated by looking at the ratios of certain radioactive isotopes (a method analogous to ‘radiocarbon dating’). Most meteorites turn out to be about 4.56 billion years old, because they come from asteroids that date from the creation of the Solar System. Anything younger must be from a planet or moon.
Scientists have found that the ratios of oxygen isotopes in meteorites are different for each parent body. Furthermore, some meteorites are found to have trapped gases whose isotopic composition exactly matches what has been measured for the atmosphere on a particular planet. Together, these strands of evidence make the origin of most meteorites pretty certain.
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