Safety and security

Fraunhofer-Gesellschaft

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Intercepting asteroids to avoid Armageddon

It sounds like the script for a Hollywood film: a giant meteorite from outer space heading straight for the Earth and threatening the destruction of mankind. And yet such a scenario does represent a real threat to our planet, as researchers reckon that we can expect an asteroid to collide with Earth every few hundred years.

In real life, though, nobody wants to rely on a rescue plan hastily improvised at the last minute. That is why the European-funded research project NEOShield was set up, with research scientists from Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI in Freiburg among those contributing to the work on the asteroid impact avoidance system. The teams of researchers are working to develop concepts designed to help avert these impacts and to alter asteroids’ orbits as they race toward Earth.

In the case of an asteroid on a collision course for Earth, scientists refer to the point in time and space when the asteroid will impact with the Earth. To prevent the impact, the asteroid has to be speeded up or slowed down so that the Earth has either passed by or is yet to arrive when the asteroid reaches the hypothetical point of collision.

»One solution would be to launch a relatively solid space probe designed to hit the asteroid at high speed,« says Professor Alan Harris from the German Aerospace Center’s Institute of Planetary Research as he explains the basic concept. Professor Harris leads the EU-funded NEOShield project. Meanwhile, scientists from Fraunhofer EMI are helping to research the foundations of this technique. »Asteroids are typically made of porous materials, so the first step is to build up a basic understanding of what happens when materials like that are hit by a foreign object,« says Dr. Frank Schäfer, head of the spacecraft technology group at Fraunhofer EMI.

To do this, he and his team use a light gas gun – one of the fastest accelerator facilities in the world. Within the gun’s approximately one-and-a-half-meter barrel, millimeter-sized pellets are accelerated to speeds of almost 10km per second. That equates to a speed of around 36,000 kilometers per hour.

The Fraunhofer scientists use what is known as a target chamber to bombard stone blocks used to approximate asteroids with a high-velocity mini projectile. The aim is to analyze with as much precision as possible how the material reacts. High-speed cameras document the experiment by taking up to 30,000 pictures per second. As in the crash testing of vehicles, the Fraunhofer researchers are interested in quantifying the force of the collision. Data are adjusted to account for actual scale and are imported continuously into computer simulations.

In the long term, NEOShield project leader Professor Harris would like to see the defense techniques that are the subject of this research tested in international space missions: »This kind of test mission is bound to throw up a few surprises, and will teach us a great deal.«

Incidentally, Harris reckons that averting an oncoming asteroid from its collision course by means of a huge explosion – just like in a Hollywood film – could in fact be an option in an emergency. Time would have to be pressing though, or the object concerned at least a kilometer in diameter.

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