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 goldennuclear-powered spacecraftlaunched 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 US$3.26 billion probe, that day is Friday, 15 September, 2017.
During a press conferenceheld 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 manoeuvre will use up the fleeting reserves of Cassini's fuel, putting it on a collision course with Saturn.
"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, saltwateroceanthat Cassini found hiding beneath the icy crust of Enceladus, a large moon of Saturn that spews water into space.
NASA's probe flew through thesecurtain-like jets of vapour and icein 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."
However, 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.
'We're going in, and we're not coming out'
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 ofchances to recordunprecedented 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 kilometres) 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. But in 2010, mission managers decided to keep itaround Saturn, reasoning they could squeeze more science out of the mission there.
However, 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."
Cassini's science-packed finale
The void between Saturn and its rings is about 1,200 miles (1930 kilometres) wide, or roughly the distance from northern Washington state to the southern tip of California.
"As we're skimming close to the planet, we'll have the best views ever of the poles of the planet," Linda Spilker, a Cassini project scientist and a planetary scientist at NASA JPL, said during the press briefing.
"We'll see the giant hurricanes at the north and south poles."
During its final orbits above Saturn, Cassini will get its closest-ever views of the hexagon-shaped feature of Saturn's north pole, which Spilker said is "two Earthdiametersacross" yet poorly understood.
"Perhaps by getting close with Cassini, we'll answer the question, 'What keeps the hexagon there in this particular shape?'" she said.
Spilker said Cassini will also photograph the auroras of Saturn's poles, measure how massive the planet's rings are, 'taste' the icy material they're made of, and even probe deep below its thick clouds to see how big its rocky core is.
Sensitive magnetic and gravitational measurements that Cassini couldn't make before may also answer lingering questions about the internal structure of Saturn, including how big its rocky core is, plus how fast a shell ofmetallic hydrogenaround it spins.
"How fast is Saturn rotating?" Spilker asked. "If there's just a slight tilt to the magnetic field, then it will wobble around and give us the length of a day."
Hours before it takes its final plunge on September 15, 2017, Cassini will beam back its last batch of images - then prepare for the end.
The fiery end of a long-time robotic friend
Cassini is a 2.78-ton robot with delicate instruments that was not designed to ram into icy ring material at 70,000 mph (112,000 km/h). It also wasn't made to plunge into the thick atmosphere of a gas giant and live to tell the tale.
Nevertheless, scientists behind the mission say they are going to do their best to shield its instruments from damage and keep the data flowing until the moment it dies.
They will do this primarily by using the cone-shaped primary antenna as a shield to protect cameras, magnetometers, and more.
"If we get surprised, well, we've got a bunch of contingency plans We'll milk the best out of this," Maize said.
He added that even if icy bits take out Cassini's ability to talk to Earth, the spacecraft "will still finish out exactly where we planned, but we'll have a little less science than we hoped for."
When Cassini begins its final plunge, it will use its last propellant to fight atmospheric drag and keep the antenna pointed at Earth.
During that time, it will 'taste' the composition of Saturn's atmosphere as it descends into the gases, broadcasting its readings in real-time back to satellite dishes on Earth.
But the measurements won't last long.
"It will break apart, it will melt, it will vaporise, and it will become a very part of the planet it left Earth 20 years ago to explore," Maize said.
While members of the Cassini team said they're looking forward to the Grand Finale, they weren't without remorse.
"It's really going to be hard to say goodbye to this plucky, capable little spacecraft that has returned all of this great science," Spilker said.
We've flown together a long time."
This article was originally published by Business Insider.
More from Business Insider:
Follow this link:
Here's how and when NASA will finally destroy Cassini - ScienceAlert
- 2D Laser Profiling Scanner for Detecting Targets - November 8th, 2009 [November 8th, 2009]
- NASA Energy Concept Could Harness the Power of Ocean Waves - November 8th, 2009 [November 8th, 2009]
- Data Acquisition Modules - November 8th, 2009 [November 8th, 2009]
- Dr. Scott Barthelmy, Research Scientist, Laboratory for High Energy Astrophysics, Goddard Space Flight Center, Greenbelt, MD - November 8th, 2009 [November 8th, 2009]
- Laser Tracker Ensures Accurate Alignment of Ares I Components - November 8th, 2009 [November 8th, 2009]
- Dual Cryogenic Capacitive Density Sensor - November 8th, 2009 [November 8th, 2009]
- Advanced Technologies Will Help Hubble Yield More Remarkable Discoveries - November 8th, 2009 [November 8th, 2009]
- Dr. Gerard Holzmann, Senior Research Scientist at the Laboratory for Reliable Software, NASA’s Jet Propulsion Laboratory - November 8th, 2009 [November 8th, 2009]
- NASA Research Will Help Aircraft Avoid Ocean Storms and Turbulence - November 8th, 2009 [November 8th, 2009]
- NASA Awards 2008 Software of the Year - November 8th, 2009 [November 8th, 2009]
- Here Come The Tricorders - Update - November 8th, 2009 [November 8th, 2009]
- China's View on Space - November 8th, 2009 [November 8th, 2009]
- Milsat Coordination and Tracking Issues - November 8th, 2009 [November 8th, 2009]
- Trash Talking and End Runs at NASA HQ - November 8th, 2009 [November 8th, 2009]
- Ares 1-Y is Toast - November 8th, 2009 [November 8th, 2009]
- Beyond Augustine - November 8th, 2009 [November 8th, 2009]
- Analyzing LCROSS' Plume - November 8th, 2009 [November 8th, 2009]
- Live Event: NASA-Sponsored Power Beaming Challenge - November 8th, 2009 [November 8th, 2009]
- JSC Wants To Build a Replicator - November 8th, 2009 [November 8th, 2009]
- USA: Looking For Ways To Hang On - November 8th, 2009 [November 8th, 2009]
- Lunar Lander Challenge Prizes Awarded - November 8th, 2009 [November 8th, 2009]
- Senate Votes To Restore NASA Budget Cuts - November 8th, 2009 [November 8th, 2009]
- New FAA Regs for Commercial Reentry - November 8th, 2009 [November 8th, 2009]
- TEDxNASA: An Invitation-Only NASA Meeting - Unless You Are Lucky - November 8th, 2009 [November 8th, 2009]
- Close Call For Courtney Stadd - November 8th, 2009 [November 8th, 2009]
- Space: A Waste? - November 8th, 2009 [November 8th, 2009]
- Making NASA Cool - November 8th, 2009 [November 8th, 2009]
- Engaging JSC’s Next Gen: A Leadership Analysis - November 8th, 2009 [November 8th, 2009]
- Dumpster Diving for Rockets - November 8th, 2009 [November 8th, 2009]
- TEDx NASA - November 8th, 2009 [November 8th, 2009]
- Reflections On a Business Trip in Huntsville - November 8th, 2009 [November 8th, 2009]
- Staying the Course - November 8th, 2009 [November 8th, 2009]
- The Economics of Space - November 8th, 2009 [November 8th, 2009]
- Ideas at Work - November 8th, 2009 [November 8th, 2009]
- Blah Blah Blah - Why We Should Care About Social Media - November 8th, 2009 [November 8th, 2009]
- Will White House Speak Soon About NASA? - December 12th, 2009 [December 12th, 2009]
- Software Aids Design of Ares V Composite Shroud Structure - December 13th, 2009 [December 13th, 2009]
- ASDX Series of silicon pressure sensors - December 13th, 2009 [December 13th, 2009]
- Industry Update: Analysis & Simulation Software - December 13th, 2009 [December 13th, 2009]
- Battery Will Provide Backup Power for Space Shuttles - December 13th, 2009 [December 13th, 2009]
- NASA Employee Claims To Have Witnessed Hijacking Planning - December 13th, 2009 [December 13th, 2009]
- Big Party in The Mojave Tonight - December 13th, 2009 [December 13th, 2009]
- Looking at Boulders on the Moon - December 13th, 2009 [December 13th, 2009]
- SpaceBook Featured by White House - December 13th, 2009 [December 13th, 2009]
- New Ways to Use Constellation Stuff - December 13th, 2009 [December 13th, 2009]
- LaRC internal Poll Update - December 13th, 2009 [December 13th, 2009]
- Coalition for Space Exploration Does a (Much Needed) Reboot - December 13th, 2009 [December 13th, 2009]
- Lunar Orbiter: Comparing Old and New Images - December 13th, 2009 [December 13th, 2009]
- Boulder Trails On The Moon - December 13th, 2009 [December 13th, 2009]
- Vote for John Grunsfeld - National Geographic Adventurer of the YeAR - December 13th, 2009 [December 13th, 2009]
- Charlie Bolden at WIA/AIAA - December 13th, 2009 [December 13th, 2009]
- Live Webcast From The Lunar Orbiter Image Recovery Project - December 13th, 2009 [December 13th, 2009]
- Big Aerospace Warns of Job Cut Impact - December 13th, 2009 [December 13th, 2009]
- The Boulders of Copernicus - December 13th, 2009 [December 13th, 2009]
- shame on us - December 13th, 2009 [December 13th, 2009]
- 2009 Space Elevator Games - December 13th, 2009 [December 13th, 2009]
- Random Hacks of Kindness - December 13th, 2009 [December 13th, 2009]
- TEDx NASA Tickets Available to the Public - December 13th, 2009 [December 13th, 2009]
- It’s better in person - December 13th, 2009 [December 13th, 2009]
- Leading Amidst the Disruptive Innovation Storm - December 13th, 2009 [December 13th, 2009]
- Space: What’s NOT to Hope for? - December 13th, 2009 [December 13th, 2009]
- Government in the Digital Age - December 13th, 2009 [December 13th, 2009]
- SpaceUp – A Space Unconference - December 13th, 2009 [December 13th, 2009]
- Starfleet Academy? - December 13th, 2009 [December 13th, 2009]
- Crowdsourcing NASA - December 13th, 2009 [December 13th, 2009]
- Bringing Home The Bacon - December 14th, 2009 [December 14th, 2009]
- Anti-Space Mom with Pro-Space Kids - December 14th, 2009 [December 14th, 2009]
- How Quickly We Forget - December 14th, 2009 [December 14th, 2009]
- WISE Launch A Success - December 14th, 2009 [December 14th, 2009]
- Dynetics Buys Orion Propulsion - December 15th, 2009 [December 15th, 2009]
- New NASA Governance Structure Under Development - December 16th, 2009 [December 16th, 2009]
- Bolden Meets With Obama on Wednesday - December 16th, 2009 [December 16th, 2009]
- MSFC Procurement Doesn't Understand what "Open Source" Means - December 16th, 2009 [December 16th, 2009]
- Bolden Meets With Obama - December 17th, 2009 [December 17th, 2009]
- Parker Griffith AT MSFC Today - December 18th, 2009 [December 18th, 2009]
- Why Your NASA Computer May Not Work Properly - December 18th, 2009 [December 18th, 2009]
- Lakes and Fog on Titan - December 18th, 2009 [December 18th, 2009]
- Waterworld Found - December 18th, 2009 [December 18th, 2009]
- Pandora Could Exist - December 18th, 2009 [December 18th, 2009]
- Laurie Leshin Is The New ESMD Deputy AA - December 18th, 2009 [December 18th, 2009]