Baku, February 10 (AZERTAC). It is not entirely clear when exactly the last major asteroid impact on Earth occurred. But there are plenty of examples of impact craters, such as the Nordlinger Ries in Bavaria. That there will be other collisions in the future is something of which Alan Harris, asteroid researcher at the German Aerospace Center, is certain.

Over the next three and a half years, he will be heading the NEOShield (Near Earth Object Shield) international collaboration, established in January 2012.

In total, 13 partners from research institutions and industry will jointly investigate the prevention of impacts by asteroids and comets. The investigations will include the impact of a space probe with the asteroids to deflect them from their threatening courses. The European Union is supporting the project with four million Euros. The partners are contributing another 1.8 million Euros.

When asteroids approach the Earth, they typically do so at a speed of between five and 30 kilometres per second. “In order to modify their orbit and prevent a collision with Earth, a force must be exerted on them,” explains Alan Harris. “And at the precise time, as well.”

Existing examples of asteroids that have followed their natural course towards Earth include the Barringer Crater in Arizona, with a diameter of 1200 metres, or the Tunguska Region in Siberia, where an asteroid explosion in 1908 uprooted millions of trees. Smaller asteroids or comets could also cause this sort of damage.

“The crater in Arizona was caused by an object about 50 metres in diameter.” There are numerous near Earth objects, or NEOs. Thousands have been discovered in the last 20 years.

“This means that a dangerous collision with Earth is likely every couple of hundred years,” the asteroid researcher estimates.

Scientists will also study a method to deflect asteroids on course for Earth without physically contacting them, if they are discovered years before their potential collision.

If a spacecraft is guided into the direct vicinity of a potentially dangerous NEO, the added gravity might have an effect on the asteroid and, as if hauling it in on a rope, gradually drag it off course. But a period of several years would be required to achieve a significant change in the asteroid`s orbit.

“To date, this method only exists on paper, but it could work.” The research to be conducted over the next three and a half years should show how realistic it is to drag threatening asteroids off track using gravity tractors.