NASA Will Destroy A $3.26 Billion Saturn Probe This Summer To Protect An Alien Water World - Physics-Astronomy.org

NASA Will Destroy A $3.26 Billion Saturn Probe This Summer To Protect An Alien Water World

The Cassini spacecraft, which launched toward Saturn in 1997, is running low on fuel.To avoid accidentally crashing into and contaminating a nearby moon that may harbor alien life, NASA is going to destroy the robot. But before Cassini perishes, it will fly between Saturn and its rings and record as much new data as possible.For nearly three decades, researchers have worked to design, build, launch, and operate an unprecedented mission to explore Saturn.

Called Cassini-Huygens — or Cassini, for short — the golden nuclear-powered spacecraft launched in October 1997, fell into orbit around the gas giant in July 2004, and has been documenting the planet and its dizzying variety of moons ever since.
But all good things must come to an end. And for NASA's $3.26 billion probe, that day is Friday, September 15, 2017.
During a press conference 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 up 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 Jet Propulsion Laboratory (JPL) who manages the Cassini mission.
Maize was referring to a warm, saltwater ocean that Cassini found hiding beneath the icy crust of Enceladus, a large 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 material, and indirectly discovered the subsurface ocean's composition — and it's one that may support alien life.
"We cannot risk an inadvertent contact with that pristine body," Maize said. "Cassini has got to be put safely away. And since we wanted to stay at Saturn, the only choice was to destroy it in some controlled fashion."
But Maize and a collaboration of researchers from 19 nations aren't going to let their plucky probe go down without a fight.

They plan to squeeze every last byte of data they can from the robot, right up until Cassini turns into a brilliant radioactive comet above the swirling storms of Saturn.
Long before Cassini began orbiting Saturn in 2004, mission managers carefully plotted out its orbits to squeeze in as many flybys of the gas giant planet, its moons, and its expansive icy rings as possible.
Their goal: Get lots of chances to record unprecedented new images, gravitational data, and magnetic readings without putting the spacecraft into harm's way or burning up too much of its limited propellant.

But after 13 years of operation at nearly 1 billion miles (1.45 billion kilometers) away from Earth, Cassini's tank is running close to empty."We're coming to the end. As it runs out of fuel, the things it can do are quite limited — until we decided on a new approach," Jim Green, the leader of NASA's planetary science program, said during the press conference.
NASA could have propelled Cassini to some other planet — perhaps Uranus or Neptune. In 2010, however, mission managers decided to keep it around Saturn, reasoning they could 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 will, for the last time, fly by Titan: an icy moon of Saturn that's bigger than our own, has 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 planet and the innermost edge of its rings.
"That last 'kiss goodbye' will put Cassini into Saturn," Maize said. "This is a roller-coaster ride. We're going in, and we are not coming out — it's a one-way trip."

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