DW.DE: How surprised were you when you heard about the meteorite that exploded over Russia?

Heiner Klinkrad: I was very surprised. We had been monitoring Asteroid 2012 DA14 very closely because it is set to pass the Earth very closely (Eds: the interview was held before the asteroid passed the Earth), and I never would have thought that a meteorite would enter the atmosphere over the Ural Mountains at about the same time.

Could this incident be related to the asteroid's passing?

No, I think it was just a coincidence. I think it is safe to exclude any connection between the two events, because the geometry of the meteorite's flight does not correspond with the trajectory of Asteroid 2012 DA14.

Is it possible to predict the explosion of a meteorite?

Meteorites are actually asteroids. They are only called meteorites once they enter the Earth's atmosphere and their parts reach its surface. As long as they are moving in space, they are asteroids.

And does the European Space Agency (ESA) observe asteroids?

Yes, we do. But we are not capable of examining and tracing each and every asteroid. That works best for larger objects. We are trying to create a catalogue of objects that are larger than a kilometer in diameter – because they can cause considerable damage.

And how big was the meteorite that crashed in Russia?

We estimate that it was about five meters large.

Would it have caused even greater damage if it had not exploded?

No. In general, meteors [reaching the Earth] in one piece cause less damage than the ones that explode. The problem is that even if these objects are only a few meters big, they heat up considerably when entering the atmosphere. With a nickel-iron-meteorite, the metal begins to melt and parts of it crash to the Earth. A smaller stone meteorite, like the one we very likely had in Russia, explodes.

Would you be able to destroy dangerous asteroids, for instance by shooting them down?

Shooting them down is difficult. But there are different concepts on how to change their trajectory. That can be done by changing the speed. The earlier you start doing that, the less the trajectory has to change in order to protect the Earth.

And how do you do that?

An asteroid travels at a speed of more than 50,000 kilometers per hour. The change in speed can be very, very small, just a couple of millimeters per second. If that can be done before, it can cause a great shift in the asteroid's position and prevent the Earth from being hit.

And how can you do that technically?

For instance by causing a nuclear explosion on the surface of a large asteroid. That leads to material evaporating, and the vapor causes leads to a change in the asteroid's speed. And that changes the trajectory of the asteroid, preventing a collision course with the Earth . Another way is to send out an object to the asteroid and cause it to crash on it with high speed. That, too, would change the asteroid's speed.

And how prepared are you to change the course of an asteroid?

We would be able to bring about a collision. The rest is more of a vision for the future.

But you haven't actually tried that out, have you?

No.

Professor Heiner Klinkrad heads the Space Debris Office at the European Space Agency (ESA) in Darmstadt, Germany.

Interview conducted by: Judith Hartl / ar