The Cassini spacecraft, which launched toward Saturn in 1997, is running low on fuel. To avoid accidentally crashing into and contaminating a close-by moon that will harbor alien life, NASA goes to destroy the robot. But before Cassini perishes, it'll fly between Saturn and its rings and record the maximum amount of new data as possible. For nearly three decades, researchers have worked to style, build, launch, and operate an unprecedented mission to explore Saturn.
Called Cassini-Huygens — or Cassini, for brief — the golden nuclear-powered spacecraft launched in October 1997, fell into orbit around the Jovian planet in July 2004, and has been documenting the earth and its dizzying form of moons ever since.
But all goodies must come to an end. And for NASA's $3.26 billion probes, that day is Friday, September 15, 2017.
During a group discussion held by the US space agency on April 4, researchers explained why they're killing off their cherished spacecraft with what they call the "Grand Finale." The maneuver will use the fleeting reserves of Cassini's fuel and put the robot on a collision course with Saturn.
False-color image showing plumes erupting from Enceladus' surface.NASA/JPL/Space Science Institute
"Cassini's own discoveries were its demise," said Earl Maize, an engineer at NASA's reaction propulsion Laboratory (JPL) who manages the Cassini mission.
Maize was pertaining to a warm, saltwater ocean that Cassini found hiding beneath the icy crust of Enceladus, an oversized moon of Saturn that spews water into space. NASA's probe flew through these curtain-like jets of vapor and ice in October 2015, "tasted" the fabric and indirectly discovered the subsurface ocean's composition — and it's one which will support alien life.
"We cannot risk an inadvertent contact therewith pristine body," Maize said. "Cassini possesses to be put safely away. And since we wanted to remain at Saturn, the sole choice was to destroy it in some controlled fashion."
But Maize and a collaboration of researchers from 19 nations aren't visiting let their plucky probe go down without a fight.
They decide to squeeze all byte of knowledge they'll from the robot, right up until Cassini turns into a superb radioactive comet above the swirling storms of Saturn.
Long before Cassini began orbiting Saturn in 2004, mission managers carefully intended its orbits to squeeze in as many flybys of the superior planet, its moons, and its expansive icy rings as possible.
Their goal: Get plenty of chances to record unprecedented new images, gravitational data, and magnetic readings without putting the spacecraft into harm's way or burning up an excessive amount of its limited propellant.
But after 13 years of operation at nearly 1 billion miles (1.45 billion kilometers) removed from Earth, Cassini's tank is running near empty."We're coming to the tip. because it runs out of fuel, the items it can do are quite limited — until we selected a brand new approach," Jim Green, the leader of NASA's planetary science program, said during the conference.
NASA could have propelled Cassini to another planet — perhaps Uranus or Neptune. In 2010, however, mission managers decided to stay it around Saturn, reasoning they might squeeze more science out of the mission there. But this effectively doomed the spacecraft to a fiery death.
Cassini's death spiral will officially begin on April 22, 2017. That's when it'll, for the last time, fly by Titan: an icy moon of Saturn that's bigger than our own, contains a thick atmosphere, seas of liquid methane, and even rain.
Titan's gravity will slingshot Cassini over Saturn, above the planet's atmosphere, and — on April 26 — through a narrow void between the earth and therefore the innermost fringe of its rings.
"That last 'kiss goodbye' will put Cassini into Saturn," Maize said. "This may be a roller-coaster ride. We're entering into, and that we aren't starting — it is a one-way trip.
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