Asteroid collision threat prompts Nasa to boost defensive measures
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A report from the US government’s National Science and Technology Council has called for improved asteroid detection, tracking and deflection in order to prevent damage from celestial impacts.
While there are no major asteroid collisions anticipated in the near future, they are often detected at a very late stage and could cause major destruction to entire regions or even continents.
The report calls for a coordinated approach between agencies in detecting asteroids and modelling and simulating their approach as they come near the Earth.
“Nasa will lead development of technologies for fast-response near-Earth object (NEO) reconnaissance missions and timely missions to deflect or disrupt hazardous NEOs,” the report said.
“Developing these technologies before an imminent threat arises will strengthen our ability to prevent NEO impact disasters.”
NEOs are defined as celestial bodies that range in size from small “meteoroids” only a few metres across, to much larger bodies several kilometres wide.
While smaller objects harmlessly fragment and disintegrate, larger objects can cause local damage or even global devastation.
“The direct effects from an NEO impact depend on its size, composition, and impact speed,” the report states.
“Small, rocky NEOs are likely to explode before hitting the ground, resulting in an airburst that could produce a wider area of moderate damage compared with a similarly sized metallic object that would strike the ground and cause heavier, more localised devastation.”
Nasa’s planetary defence officer Lindley Johnson said scientists have found 95 per cent of NEOs that measure a kilometre or bigger, but the hunt is on for the remaining 5 per cent and smaller rocks that could still inflict big damage.
It has catalogued 18,310 objects of all sizes. Just over 800 of these are 140 metres or bigger.
There is no quick solution if a space rock is suddenly days, weeks or even months from striking, according to Johnson, but such short notice would give the world time to evacuate the area it might hit.
Ground telescopes are good at picking up asteroids zooming into the inner solar system and approaching from the night side of Earth, Johnson said. What is difficult to detect are rocks that have already zipped past the Sun and are heading out of the solar system, approaching from the day side.
That is apparently what happened in 2013 when an asteroid about 20 metres in size suddenly appeared and exploded over Chelyabinsk, Russia, damaging thousands of buildings and causing widespread injuries.
An asteroid double or even triple that size exploded over Tunguska, Russia, in 1908, levelling 2,000 square kilometres of forest. According to the report released on Wednesday, casualties could be in the millions if a similar event struck New York City.
A giant space rock wiped out the dinosaurs when it smacked into Mexico’s Yucatan peninsula 65 million years ago.
Johnson stressed it would take years to attempt to turn away a potential killer asteroid – several years to build a spacecraft then another few years to get it to the target. Ideally, he would like at least 10 years notice.
A mission to defend Earth could involve hitting the asteroid or comet with big, fast-moving robotic spacecraft in the hope of changing its path, or, in the worst case, launching a nuclear device not to blow up the asteroid but to superheat its surface and blow off enough material to divert it.
Concern over threats from space, both manmade and pre-existing, have been ramping up in recent weeks.
Earlier this week US President Donald Trump ordered the Pentagon to create a new branch of the military to defend American interests in space.
France’s defence minister has also called for greater investment in surveillance of outer space to ensure it never becomes an arena for future wars.
“We must be able to invest more in space than we do today so that we can monitor it and prevent it from becoming a theatre for major confrontations,” Florence Parly told France 2 television.
Parliament is currently debating France’s 2019-2025 military planning law, which states that “space is of prime strategic interest”.
“In the face of increasing risks and threats, the continued strengthening of new space assets and the systems using them is needed,” the draft legislation states.