Cassini grand finale: Nasa breaks up above Saturn after historic 20-year mission

Cassini grand finale: Nasa breaks up above Saturn after historic 20-year mission  Even as Nasa’s Cassini probe hurtled towards its final, fiery destruction in the atmosphere above Saturn, controllers back on Earth were hoping it would reveal one final secret. The 20-year mission to investigate the ringed planet and its moons had been hailed as one of the dazzling successes of space exploration, yet it had so far failed to solve one of Saturn’s most intriguing riddles: why the northern hemisphere has a shorter day than the southern. Scientists believe the answer lies in the mosaic of magnetic fields near the planet’s surface. The only way to pass through them, however, was as part of a suicide dive. Ligeia Mare, a hydrocarbon sea on Saturn's moon Titan Credit: NASA Yesterday, as the 22-foot craft buffeted through Saturn’s upper layer of clouds, scientists at Jet Propulsion Laboratory in Pasadena, California, were left praying the 20th Century-built machine could keep stable long enough to collect and transmit the vital data. Teams will now spend months poring over the new information, but the early indications look positive – the probe was beaming back information right until the end. “Cassini performed exactly as she was supposed to,” said Professor Jonathan Lunine, from Cornell University, New York, meanwhile Astronomer Royal Lord Rees described the final descent as the “grand finale of the greatest scientific and engineering achievements in space exploration.” Saturn’s out-of-sync hemispheres have baffled scientists since Cassini first spotted the variation when it arrived in 2004. The north pole of Saturn's icy moon Enceladus Credit: NASA While the northern hemisphere completes a full rotation in approximately 10.6 hours, in the south it takes 10.8 hours. Dr Daniel Brown, an astronomer at Nottingham Trent University, said cracking this conundrum would yield insights into the science of planet formation in general. Central to that endeavour was Cassini’s 30-foot protruding boom, housing the magnetometer, which is certain to have been ripped off seconds after the craft lost contact as it spun out of control at 77,000 miles per hour. So important was this information, Nasa prioritised collecting it in the precious final few moments at low altitude in favour of taking pictures, the last of which were transmitted on Thursday. Cassini-Huygens: 20 years of images 01:32 The craft had been low on fuel a decision was taken not to let it indefinitely drift. At mission control, technicians who had devoted decades to Cassini were overcome with emotion when the signal was lost at 12.55pm UK time. Nasa's Earl Maize addressed fellow controllers: "Congratulations to you all," he said. "This has been an incredible mission, an incredible spacecraft and you're all an incredible team. I'm going to call this end of mission. Project manager off the net." Earl Maize speaks during a press conference held after the end of the Cassini Credit: NASA Arriving at Saturn seven years after blast-off from Cape Canaveral in 1997, Cassini was originally only intended to spend three years observing the planet and its moons, before controllers decided they would extend the flight by another decade. Over the course of the mission, Cassini discovered seven new moons, six of which have been named, observed raging storms on Saturn, and shed new light on the planet's famous rings. One of the most significant findings was that of an ocean under the icy surface of Enceladus which may harbour life. The mission made international headlines in 2005 when it landed an orbiter, Huygens, on Saturn’s largest moon, Titan. Hyperion, one of Saturn's outer moons Credit: NASA At almost every stage, the project has been supported by British scientists, including Professor John Zarnecki, President of the Royal Astronomical Society. “I worked on Cassini/Huygens for more than 20 years so of course I feel slightly sad,” he said. “But it’s given me the most wonderful ride and it delivered my instrument to the surface of Titan where it’s still sitting. “It has shown Titan to be even more wonderful than we had ever imagined – we’ve seen seas and lakes and rivers and dune fields and clouds and rain and more. “The data we collected is unlikely to be bettered for many decades to come. “The mission has not only been a wonderful scientific success but has also shown what can be achieved when scientists and engineers from across the world can work together with a common purpose to realise lofty goals.”     Earth appears as a pale blue dot below Saturn's majestic rings in this stunning image taken by the Cassini space probe – can you spot it? Credit:  PA What was the purpose of the Cassini mission? To study Saturn and its moons from close up and in the process learn more about the solar system and how it was formed. Scientists were especially interested in Saturn's giant moon Titan, which has a nitrogen and methane atmosphere and in some ways resembles an early version of Earth. The whole mission cost £2.9 billion. When was Cassini launched and how long did it take to reach Saturn? Cassini was launched from Cape Canaveral, Florida, in 1997 and took seven years to reach Saturn, travelling two billion miles. On the way it made fly-bys of Venus, the Earth, and Jupiter to receive gravitational "kicks" that boosted its speed to more than 42,500mph. Cassini arrived at the ringed planet in July 2004. What was the purpose of the Cassini mission? To study Saturn and its moons from close up and in the process learn more about the solar system and how it was formed. Scientists were especially interested in Saturn's giant moon Titan, which has a nitrogen and methane atmosphere and in some ways resembles an early version of Earth. The whole mission cost £2.9 billion. Read more:  Nasa waves emotional goodbye to Cassini after death plunge into Saturn 



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