Nasa gaffe that rocked the globe

09 January 2005 | 15:22 Code : 4621 Geoscience events
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IT WILL go down as the most extreme example of crying wolf in the history of mankind. Scientists who terrified the life out of millions of people over Christmas by issuing an asteroid strike red alert have now admitted they got their sums wrong.
IT WILL go down as the most extreme example of crying wolf in the history of mankind.

Scientists who terrified the life out of millions of people over Christmas by issuing an asteroid strike red alert have now admitted they got their sums wrong.
While most people prepared for the seasonal festivities, teams from the US and Italy were nervously studying a 440-yard-long chunk of rock in space called 2004 NM4.
After carrying out calculations, and two days before Christmas, the scientists announced to the world that in 2029 there was a one in 37 chance of a hit. Those odds and size of the asteroid made it the biggest threat to the planet ever recorded.
Panicked sky-watchers across the globe debated what could be done in the next 24 years to avert a collision, an event that could wipe out millions of people.

But after carrying out further calculations, the scientists realised they had bungled: the asteroid would sail past Earth at the relatively comfortable distance of 37,000 miles and mankind was safe - for now.

The asteroid was first spotted in June last year before being rediscovered shortly before Christmas, allowing astronomers to calculate its course across the solar system.
Initially, the teams at Nasa’s Jet Propulsion Laboratory and the University of Pisa estimated it had just a 1 in 300 chance of hitting the Earth on Friday, April 13, 2029 but subsequent calculations dramatically narrowed the likelihood of impact.

The risk posed by asteroids to Earth are calculated using a measurement known as the Terino Impact Hazard Scale, which plots the probability of an object hitting the Earth against the energy it will have on impact.

Before Christmas, astronomers had never spotted an asteroid with a Terino number greater than 2, but 2004 NM4 was found to have a Terino risk of 4.

"In terms of the damage this would do, it would cause significant regional devastation," said Kevin Yates from the Near Earth Object Information Centre in Leicester.

"This certainly got everybody quite excited. It was the highest ever probability we have ever had, so there were a lot of people staying in touch over the festive period to see what was happening."
Slamming into the Earth at an estimated 6,000mph, the initial blast from the strike would destroy everything in the immediate area while the shock wave would cause widespread death and destruction for miles. The material ejected from the blast site would enter the Earth’s atmosphere, causing global cooling and unleashing further disaster.
A week after Nasa’s original announcement on December 23, its astronomers around the world were frantically searching for extra data.

Jeff Larson, of the Spacewatch Observatory at the University of Arizona, found the project’s telescopes had spotted the asteroid back in March but it had gone unnoticed.
With the extra data on the asteroid’s orbit around the sun these sightings provided, Nasa was then able to work out 2004 NM4 would slip harmlessly past between the Earth and the Moon.
Scottish meteorite expert Rob Elliot said the US space agency risked crying wolf.
He said: "Nasa has a habit of announcing objects are going to hit the Earth with frightening regularity.
"They hype up a sighting on very little data before carrying out more calculations which diminish the risk.
"Unfortunately some people take these scares to heart and many people are sick and tired of it.
"There is a certain amount of resentment from the meteorite community that they keep doing this. They should only really release a statement if it warrants it."
But Donald Yeoman, manager of Nasa’s JPL, said: "We have to decide if we do these calculations in private whether to release the data when it is definite or put everything out there in real time. We choose to take the latter option as it is in line with our policy of keeping the public informed.

"On this occasion the object got a much higher risk rating than anything else we have seen in tens of years of doing this. Our subsequent computations gave us possible locations of NM4 in 2029 which did not involve either the Earth or the Moon, ruling out a strike."
John Davies, an astronomer at the Royal Observatory Edinburgh, backed Nasa. He said: "It is a difficult situation for astronomers to know when to say something.

"If they say something too early then they can be accused of crying wolf and if they wait too long then people ask if they have been asleep.

"With something that is not predicted to impact for 25 or 50 years though, waiting a week for further calculations is not going to make much difference.
"One thing this high Terino scale rating has done is to focus our attention on making sure the right procedures are in place on how to respond should another one come along."
The asteroid’s estimated size has been worked out from its brightness, which assumes its reflectivity is similar to that of other asteroids that have been observed.
The closest known near miss in recent times happened last March when a 10-yard asteroid came within 4,000 miles of the planet. The same month, an asteroid 33 yards across missed the planet by 16,780 miles.

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