It was a journey ten years in the making as the spacecraft Rosetta became the first ever to catch up with a comet.

For scientists, it was a landmark moment. .

(SOUNDBITE) (German) HEAD OF THE SATELLITE CONTROL CENTER AT THE EUROPEAN SPACE OPERATIONS CENTER, THOMAS REITER, SAYING:

"Of course it is a relief, it was a long journey and now this is a really emotional moment that it has now arrived at the comet."

Scientists like Thomas Reiter of the European Space Operations Center hope Rosetta will help unlock some of the secrets of the solar system. But first, there's an even greater challenge to overcome. In November they will attempt to land the probe on the comet's surface.

(SOUNDBITE) (German) HEAD OF THE SATELLITE CONTROL CENTER AT THE EUROPEAN SPACE OPERATIONS CENTER, THOMAS REITER, SAYING:

"We hope of course to find organic molecules on the comet but perhaps also molecules which are relevant for the creation of life on earth. That would be specta