Home Science Asteroid detection: Expert reveals how astronomers track rogue space rocks

Asteroid detection: Expert reveals how astronomers track rogue space rocks

The number of discovered near-Earth asteroids totalled more than 22,000 as of last year, according to US-based space agency NASA. And with an average of 30 new space rock discoveries added each week, the importance detecting potentially deadly asteroids continues to grow.

NASA has consequently been readying planetary defence from asteroid strikes for years.

steroids passing much nearer to the Earth actually can be seen moving across the background stars

Professor Alan Harris

Alan Harris, Emeritus Professor and senior scientist at the German Aerospace Center (DLR) has revealed really do pose a real, if small danger to life on Earth.

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He told Express.co.uk: “It’s a very small risk compared to other risks that we face these days, but it is potentially totally catastrophic.”

“Asteroid and comet impacts occur very infrequently but there are big objects capable of hitting Earth that have the potential to virtually wipe out complete countries, especially smaller, say European-size countries.

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Asteroid detection: An expert has revealed how astronomers track rogue space rocks (Image: NASA/Getty)

Asteroid news: Asteroids impacts remain one of the greatest existential threats to mankind (Image: Express)

“Fortunately, these sorts of impacts take place at every few hundred thousand years also so normally we don’t have to worry about it.

“But the problem is it’s a statistical phenomenon and it could virtually happen at any time without a lot of warning.”

Professor Harris also revealed the difficulties of asteroid detection, even when armed with cutting-edge technology.

He said: “There are several observatories, mainly funded by the Americans, who have quite a large Planetary Defence program.

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Asteroid detection: Some space rocks are very valuable (Image: Express)

Asteroid detection: Four asteroids could one day collide with Earth (Image: Express)

“They look for objects which are moving fairly rapidly against the background of stars because stars don’t appear to move because they’re so far away.

“But asteroids passing much nearer to the Earth actually can be seen moving across the background stars even during a single night.

“And so they take the exposures of as much of the sky as they can per night.

“And they compare, say, a couple of exposures at one time, and then they return minutes later and look at that part of the sky again.

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“They have special software that detects moving objects – you can very easily see if you compared to pictures, what has moved in that picture.”

They can sort of join the dots if you like and calculate a track across the sky, which they can calculate an orbit from the positions the object moves through during during the night.

“And if the object possibly could hit the Earth, you obviously need to have as accurate an orbit as possible and therefore it is important to keep on tracking this newly-discovered nearest object for as long as possible.”

However, ground-based telescopes alone have limitations – for instance, they can only survey the skies at night and in clear skies.

Based on statistical population estimates, about two thirds of NEOs larger than 460 feet still remain to be discovered.

Asteroid news: Pictured is a meteor crater in Arizona (Image: Alan Harris)

NASA is proposing the Near-Earth Object Camera to detect asteroids (Image: NASA)

NASA Near-Earth Object Camera:

NASA is accelerating plans to launch an infrared telescope capable of detecting asteroids on a collision course with Earth.

The launch could arrive by the middle of the next decade, Thomas Zurbuchen, NASA’s associate administrator announced last year

The Near-Earth Object Surveillance Mission, which will cost $ 500 million to $ 600 million, grows out of long-gestating plans for the Near-Earth Object Camera (NEOCam), first proposed by NASA’s Jet Propulsion Lab (JPL) in Pasadena, California, nearly 15 years ago.

Such a scope is essential for meeting a congressional requirement that NASA detect 90 percent of all potentially hazardous asteroids and comets of at least 450ft (140m) in diameter by the end of the year.

What is NASA’s Planetary Defence program?

Planetary defence is the term used to encompass all the capabilities needed to detect the possibility and warn of potential asteroid or comet impacts with Earth, and then either prevent them or mitigate their possible effects.

This involves finding and tracking near-Earth objects that pose of hazard of impacting Earth.

Once an asteroid is discovered, the agency determine its orbit, trajectory, size, shape, mass, composition, rotational dynamics and other parameters.

This allows experts to determine the severity of the potential impact event, warn of its timing and potential effects, and calculate the means to mitigate the impact.

Measures can then be taken to deflect or disrupt an asteroid on an impact course with Earth, or to mitigate the effects of an impact that cannot be prevented.

Mitigation measures that can be taken on Earth to protect lives and property include evacuation of the impact area and migration of critical infrastructure.

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