Cassini, one of Nasa's most important spacecraft, slams into Saturn and gets destroyed

The planet Saturn is seen in the first color composite made of images taken by NASA's Cassini spacecraft on its approach to the ringed planet, October 21, 2002 NASA/Getty Images

Cassini, one of Nasa's most important spacecrafts, has crashed into Saturn and been destroyed.

The agency sent the craft to burn up on the planet's surface to stop it spreading alien bacteria carried there from Earth. To avoid that, Cassini fell into Saturn's atmosphere and burnt up like a meteor, spreading itself across the planet it has been exploring since it set off from Earth in 1997.

Cassini was actually destroyed more than an hour before the last signal reached Earth, but the messages take so much time to spread across the solar system that Nasa only just saw the signal drop off. When it did, the radio waves that engineers were watching live dropped off, as the equipment required to send them back to Earth burnt up.

"The signal from the spacecraft has gone, and within 45 seconds so will the spacecraft," the project manager of the Cassini mission said. "I hope you're all as deeply proud fo this amazing accomplishment. Congratulations to you all. This has been an incredible mission, an incredible spacecraft, and you've all been an incredible team."

The engineers working in Nasa's control centre then applauded.

The destruction of the craft went entirely to plan, Nasa said. It had been forced to send it to Saturn where it would burn up and avoid accidentally landing on another moon – like Titan or Enceladus – which it might accidentally end up populating with aliens.

Scientists have described the loss of the craft with a mix of pride and sadness. It managed to learn much more than was expected, but researchers describe the sadness of losing the craft and so receiving no more information from it.

But work will continue using all the data that has already been transmitted back from the craft. That includes the pitures it sent right up until the end, taking last photos of the system over Thursday and then sending back samples of Saturn's atmosphere at the same time as it was being destroyed by it.

And researchers say that one of Cassini's most lasting legacies will be as an argument for going back to see Saturn and its moons.