Saturn Probe Cassini is incinerated

The American-led Cassini space mission to Saturn has just come to a spectacular end.

Controllers had commanded the probe to destroy itself by plunging into the planet’s atmosphere.

It survived for just over a minute before being broken apart.

Cassini had run out of fuel and Nasa had determined that the probe should not be allowed simply to wander uncontrolled among Saturn and its moons.

The loss of signal from the spacecraft occurred pretty close to the prediction. At mission control, at the Jet Propulsion Laboratory in Pasadena, California, the drop-off was timed at 04:55 PDT.

Nasa’s Earl Maize addressed fellow controllers: “Congratulations to you all. This has been an incredible mission, an incredible spacecraft and you’re all an incredible team. I’m going to call this the end of mission. Project manager off the net.”

The statement brought restrained applause and some comforting embraces.

The loss of signal indicated that the probe was tumbling wildly in the planet’s gases. Travelling downwards at over 120,000km/h, it could have survived the violence for no more than about 45 seconds before being torn to pieces.

Incineration in the heat and pressure of the plunge was inevitable - but Cassini still managed to despatch home some novel data on the chemical composition of Saturn’s atmosphere.

This moon was seen to spurt water vapour into space from cracks at its south pole. The H20 came from an ocean held beneath the icy shell of Enceladus.

When Cassini flew through the water plumes, it showed that conditions in the sub-surface ocean were very probably suitable for life.

Today, scientists are already talking about how they can go back with another, more capable probe to investigate this idea further.

A great many of those researchers have been gathered this week at the nearby campus of the California Institute of Technology. They watched a feed from the control room at JPL on giant screens.

Jonathan Lunine, from Cornell University at Ithaca, New York, spoke for many when he said: “I feel sad but I’ve felt sad the whole week; we knew this was going happen. And Cassini performed exactly as she was supposed to and I bet there is some terrific data on the ground now about Saturn’s atmosphere.”

And Linda Spilker, the Nasa Cassini project scientist, added: “When I look back on the Cassini mission I see a mission that was running a 13-year marathon of scientific discovery. And this last orbit was just the last lap. And so we stood in celebration of successfully completing the race. And I know I stood there with a mixture of tears and applause.”

Although the probe has gone its science lives on. It has acquired a huge amount of data that will keep researchers busy for decades to come. A lot of it has barely even been assessed.

“Linda Spliker and I were joking earlier that those last few seconds of the Cassini mission - our first ‘taste’ of the atmosphere of Saturn - might be a number of PhD theses for students to come,” observed Michael Watkins, the director of JPL. “So, even in those last few seconds, it will continue its re-writing of the textbooks.”