After almost 20 years in space, the final countdown has started for Saturn mission spacecraft Cassini.
Faced with running out fuel, NASA scientists have decided to crash and burn the Cassini in the gas clouds of Saturn.
Controllers in charge of the mission have set in motion a death spiral that will take the spacecraft on a series of loops between the giant planet and the mysterious rings that surround it.
The mission will end around September 15, when Cassini plunges to destruction, burning up in Saturn’s atmosphere.
This grand showdown solves two problems for mission control – what to do with a spacecraft no longer responding to orders because it has no fuel and giving scientists answers to questions like how old the planet’s rings of ice are, how long a day is on Saturn and more information about what lies beneath the choking gas clouds.
“We sort of know the day lasts about 10.5 hours,” said Prof Michele Dougherty, the Cassini magnetometer principal investigator from Imperial College, London.
“It changes depending on if you’re looking in the northern hemisphere or the southern hemisphere. And depending on whether you’re looking in the summer or winter seasons – it changes as well.”
Cassini is almost seven metres high and four metres wide.
The inside is packed with scientific instruments, such as radar, imaging systems, infrared mapping tools and equipment for analysing cosmic dust.
The spacecraft was launched from Cape Canaveral, Florida, on October 15, 1997 and travelled 2.2 billion miles to reach Saturn. On the way, the mission flew by Venus and Jupiter to gather data.
Crash landing risk
The mission was planned to last just four years, but was extended twice in 2008 and 2010.
Cassini has cost the US and European space agencies $3.22 billion and provided 5,000 jobs in 17 countries.
“If Cassini runs out of fuel it would be uncontrolled and the possibility that it could crash-land on the moons of Titan or Enceladus and pollute the environment are unacceptably high,” said Dr Earl Maize, NASA’s Cassini programme manager.
“We could put it into a very long orbit far from Saturn but the science return from that would be nowhere near as good as what we’re about to do.”