Grandfinale - Blog Posts

Ultra-Close Orbits of Saturn = Ultra-Cool Science

On Sept. 15, 2017, our Cassini spacecraft ended its epic exploration of Saturn with a planned dive into the planet’s atmosphere–sending back new science to the very last second. The spacecraft is gone, but the science continues!

New research emerging from the final orbits represents a huge leap forward in our understanding of the Saturn system -- especially the mysterious, never-before-explored region between the planet and its rings. Some preconceived ideas are turning out to be wrong while new questions are being raised. How did they form? What holds them in place? What are they made of?

Six teams of researchers are publishing their work Oct. 5 in the journal Science, based on findings from Cassini's Grand Finale. That's when, as the spacecraft was running out of fuel, the mission team steered Cassini spectacularly close to Saturn in 22 orbits before deliberately vaporizing it in a final plunge into the atmosphere in September 2017.

Knowing Cassini's days were numbered, its mission team went for gold. The spacecraft flew where it was never designed to fly. For the first time, it probed Saturn's magnetized environment, flew through icy, rocky ring particles and sniffed the atmosphere in the 1,200-mile-wide (2,000-kilometer-wide) gap between the rings and the cloud tops. Not only did the engineering push the spacecraft to its limits, the new findings illustrate how powerful and agile the instruments were.

Many more Grand Finale science results are to come, but today's highlights include:

Complex organic compounds embedded in water nanograins rain down from Saturn's rings into its upper atmosphere. Scientists saw water and silicates, but they were surprised to see also methane, ammonia, carbon monoxide, nitrogen and carbon dioxide. The composition of organics is different from that found on moon Enceladus – and also different from those on moon Titan, meaning there are at least three distinct reservoirs of organic molecules in the Saturn system.

For the first time, Cassini saw up close how rings interact with the planet and observed inner-ring particles and gases falling directly into the atmosphere. Some particles take on electric charges and spiral along magnetic-field lines, falling into Saturn at higher latitudes -- a phenomenon known as "ring rain." But scientists were surprised to see that others are dragged quickly into Saturn at the equator. And it's all falling out of the rings faster than scientists thought -- as much as 10,000 kg of material per second.

Scientists were surprised to see what the material looks like in the gap between the rings and Saturn's atmosphere. They knew that the particles throughout the rings ranged from large to small. They thought material in the gap would look the same. But the sampling showed mostly tiny, nanograin- and micron-sized particles, like smoke, telling us that some yet-unknown process is grinding up particles. What could it be? Future research into the final bits of data sent by Cassini may hold the answer.

Saturn and its rings are even more interconnected than scientists thought. Cassini revealed a previously unknown electric current system that connects the rings to the top of Saturn's atmosphere.

Scientists discovered a new radiation belt around Saturn, close to the planet and composed of energetic particles. They found that while the belt actually intersects with the innermost ring, the ring is so tenuous that it doesn’t block the belt from forming.

Unlike every other planet with a magnetic field in our Solar System, Saturn's magnetic field is almost completely aligned with its spin axis. Think of the planet and the magnetic field as completely separate things that are both spinning. Both have the same center point, but they each have their own axis about which they spin. But for Saturn the two axes are essentially the same – no other planet does that, and we did not think it was even possible for this to happen. This new data shows a magnetic-field tilt of less than 0.0095 degrees. (Earth's magnetic field is tilted 11 degrees from its spin axis.) According to everything scientists know about how planetary magnetic fields are generated, Saturn should not have one. It's a mystery physicists will be working to solve.

Cassini flew above Saturn's magnetic poles, directly sampling regions where radio emissions are generated. The findings more than doubled the number of reported crossings of radio sources from the planet, one of the few non-terrestrial locations where scientists have been able to study a mechanism believed to operate throughout the universe. How are these signals generated? That’s still a mystery researchers are looking to uncover.

For the Cassini mission, the science rolling out from Grand Finale orbits confirms that the calculated risk of diving into the gap -- skimming the upper atmosphere and skirting the edge of the inner rings -- was worthwhile.

Almost everything going on in that region turned out to be a surprise, which was the importance of going there, to explore a place we'd never been before. And the expedition really paid off!

Analysis of Cassini data from the spacecraft’s instruments will be ongoing for years to come, helping to paint a clearer picture of Saturn.

To read the papers published in Science, visit: URL to papers

To learn more about the ground-breaking Cassini mission and its 13 years at Saturn, visit: https://www.nasa.gov/mission_pages/cassini/main/index.html

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Cassini Mission: What’s Next?

It’s Friday, Sept. 15 and our Cassini mission has officially come to a spectacular end. The final signal from the spacecraft was received here on Earth at 7:55 a.m. EDT after a fateful plunge into Saturn’s atmosphere.

After losing contact with Earth, the spacecraft burned up like a meteor, becoming part of the planet itself.

Although bittersweet, Cassini’s triumphant end is the culmination of a nearly 20-year mission that overflowed with discoveries.

But, what happens now?

Mission Team and Data

Now that the spacecraft is gone, most of the team’s engineers are migrating to other planetary missions, where they will continue to contribute to the work we’re doing to explore our solar system and beyond.

Mission scientists will keep working for the coming years to ensure that we fully understand all of the data acquired during the mission’s Grand Finale. They will carefully calibrate and study all of this data so that it can be entered into the Planetary Data System. From there, it will be accessible to future scientists for years to come.

Even beyond that, the science data will continue to be worked on for decades, possibly more, depending on the research grants that are acquired.

Other team members, some who have spent most of their career working on the Cassini mission, will use this as an opportunity to retire.

Future Missions

In revealing that Enceladus has essentially all the ingredients needed for life, the mission energized a pivot to the exploration of “ocean worlds” that has been sweeping planetary science over the past couple of decades.

Jupiter’s moon Europa has been a prime target for future exploration, and many lessons during Cassini’s mission are being applied in planning our Europa Clipper mission, planned for launch in the 2020s.

The mission will orbit the giant planet, Jupiter, using gravitational assists from large moons to maneuver the spacecraft into repeated close encounters, much as Cassini has used the gravity of Titan to continually shape the spacecraft’s course.

In addition, many engineers and scientists from Cassini are serving on the new Europa Clipper mission and helping to shape its science investigations. For example, several members of the Cassini Ion and Neutral Mass Spectrometer team are developing an extremely sensitive, next-generation version of their instrument for flight on Europa Clipper. What Cassini has learned about flying through the plume of material spraying from Enceladus will be invaluable to Europa Clipper, should plume activity be confirmed on Europa.

In the decades following Cassini, scientists hope to return to the Saturn system to follow up on the mission's many discoveries. Mission concepts under consideration include robotic explorers to drift on the methane seas of Titan and fly through the Enceladus plume to collect and analyze samples for signs of biology.

Atmospheric probes to all four of the outer planets have long been a priority for the science community, and the most recent recommendations from a group of planetary scientists shows interest in sending such a mission to Saturn. By directly sampling Saturn's upper atmosphere during its last orbits and final plunge, Cassini is laying the groundwork for an potential Saturn atmospheric probe.

A variety of potential mission concepts are discussed in a recently completed study — including orbiters, flybys and probes that would dive into Uranus' atmosphere to study its composition. Future missions to the ice giants might explore those worlds using an approach similar to Cassini's mission.

Learn more about the Cassini mission and its Grand Finale HERE.

Follow the mission on Facebook and Twitter for the latest updates.

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After 20 years in space, the Cassini spacecraft is running out of fuel. In 2010, Cassini began a seven-year mission extension in which the plan was to expend all of the spacecraft’s propellant exploring Saturn and its moons. This led to the Grand Finale and ends with a plunge into the planet’s atmosphere at 6:32 a.m. EDT on Friday, Sept. 15.

The spacecraft will ram through Saturn’s atmosphere at four times the speed of a re-entry vehicle entering Earth’s atmosphere, and Cassini has no heat shield. So temperatures around the spacecraft will increase by 30-to-100 times per minute, and every component of the spacecraft will disintegrate over the next couple of minutes…

Cassini’s gold-colored multi-layer insulation blankets will char and break apart, and then the spacecraft's carbon fiber epoxy structures, such as the 11-foot (3-meter) wide high-gain antenna and the 30-foot (11-meter) long magnetometer boom, will weaken and break apart. Components mounted on the outside of the central body of the spacecraft will then break apart, followed by the leading face of the spacecraft itself.

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Solar System: Things to Know This Week

With only four months left in the mission, Cassini is busy at Saturn. The upcoming cargo launch, anniversaries and more!

As our Cassini spacecraft made its first-ever dive through the gap between Saturn and its rings on April 26, 2017, one of its imaging cameras took a series of rapid-fire images that were used to make this movie sequence. Credits: NASA/JPL-Caltech/Space Science Institute/Hampton University

1-3. The Grand Finale

Our Cassini spacecraft has begun its final mission at Saturn. Some dates to note:

May 28, 2017: Cassini makes its riskiest ring crossing as it ventures deeper into Saturn's innermost ring (D ring).

June 29, 2017: On this day in 2004, the Cassini orbiter and its travel companion the European Space Agency's Huygens probe arrived at Saturn.

September 15, 2017: In a final, spectacular dive, Cassini will plunge into Saturn - beaming science data about Saturn's atmosphere back to Earth to the last second. It's all over at 5:08 a.m. PDT.

More about the Grand Finale

4. Cargo Launch to the International Space Station

June 1, 2017: Target date of the cargo launch. The uncrewed Dragon spacecraft will launch on a Falcon 9 from Launch Complex 39A at our Kennedy Space Center in Florida. The payload includes NICER, an instrument to measure neutron stars, and ROSA, a Roll-Out Solar Array that will test a new solar panel that rolls open in space like a party favor.

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5. Sojourner

July 4, 2017: Twenty years ago, a wagon-sized rover named Sojourner blazed the trail for future Mars explorers - both robots and, one day, humans. Take a trip back in time to the vintage Mars Pathfinder websites:

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6. Voyager

August 20, 2017: Forty years and still going strong, our twin Voyagers mark 40 years since they left Earth.

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7. Total Solar Eclipse

August 21, 2017: All of North America will be treated to a rare celestial event: a total solar eclipse. The path of totality runs from Oregon to South Carolina.

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8. From Science Fiction to Science Fact

Light a candle for the man who took rocketry from science fiction to science fact. On this day in 1882, Robert H. Goddard was born in Worcester, Massachusetts.

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9. Looking at the Moon

October 28, 2017: Howl (or look) at the moon with the rest of the world. It's time for the annual International Observe the Moon Night.

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10. Last Human on the Moon

December 13, 2017: Forty-five years ago, Apollo 17 astronaut Gene Cernan left the last human footprint on the moon.

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Discover more lists of 10 things to know about our solar system HERE.

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Take a dive between Saturn and its rings to see what our Cassini spacecraft saw during its first daring plunge on April 26! 

As Cassini made its first-ever dive through the gap between Saturn and its rings on April 26, 2017, one of its imaging cameras took a series of rapid-fire images that were used to make this movie sequence. The video begins with a view of the vortex at Saturn's north pole, then heads past the outer boundary of the planet's hexagon-shaped jet stream and continues further southward. 

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

This unprocessed image shows features in Saturn's atmosphere from closer than ever before. The view was captured by our Cassini spacecraft during its first Grand Finale dive between the planet and its rings on April 26, 2017.

As Cassini dove through the gap, it came within about 1,900 miles (3,000 kilometers) of Saturn's cloud tops (where the air pressure is 1 bar -- comparable to the atmospheric pressure of Earth at sea level) and within about 200 miles (300 kilometers) of the innermost visible edge of the rings.

See all the unprocessed images from Cassini: https://saturn.jpl.nasa.gov/galleries/raw-images/ 

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The Start of Cassini’s Grand Finale

Cue drumroll…

For the first time ever, our Cassini spacecraft dove through the narrow gap between Saturn and its rings on April 26. At 5 a.m. EDT, Cassini crossed the ring plane with its science instruments turned on and collecting data. 

During this dive, the spacecraft was not in contact with Earth. The first opportunity to regain contact with the spacecraft is expected around 3 a.m. EDT on April 27.

This area between Saturn and its rings has never been explored by a spacecraft before. What we learn from these daring final orbits will further our understanding of how giant planets, and planetary systems everywhere, form and evolve.

So, you might be asking…how did this spacecraft maneuver its orbit between Saturn and its rings? Well…let us explain!

On April 22, Cassini made its 127th and final close approach to Saturn’s moon Titan. The flyby put the spacecraft on course for its dramatic last act, known as the Grand Finale. 

As the spacecraft passed over Titan, the moon’s gravity bent its path, reshaping the robotic probe’s orbit slightly so that instead of passing just outside Saturn’s main rings, Cassini would begin a series of 22 dives between the rings and the planet.

With this assist, Cassini received a large increase in velocity of approximately 1,925 mph with respect to Saturn.

This final chapter of exploration and discovery is in many ways like a brand-new mission. Twenty-two times, the Cassini spacecraft will dive through the unexplored space between Saturn and its rings. What we learn from these ultra-close passes over the planet could be some of the most exciting revelations ever returned by the long-lived spacecraft.

Throughout these daring maneuvers, updates will be posted on social media at:

@CassiniSaturn on Twitter @NASAJPL on Twitter

Updates will also be available online at: https://saturn.jpl.nasa.gov/mission/grand-finale/milestones/ 

Follow along with us during this mission’s Grand Finale!

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Solar System: Things to Know This Week

Like sailors of old, the Cassini mission team fondly thinks of the spacecraft as "she."  On April 22, she begins her Grand Finale, a spectacular end game—22 daring dives between the planet's atmosphere and innermost rings. Here are 10 things to know about her Grand Finale.

1. She's Broadcasting Live This Week

On Tuesday, April 4 at 3 p.m. EDT  (noon PDT), At Jet Propulsion Laboratory, the Cassini team host a news briefing to discuss the mission's Grand Finale.

Tune in Tuesday: youtube.com/nasajpl/live

2. She's Powered in Part By ... Titan

Cassini left Earth with less than 1/30th of the propellant needed to power all her adventures at Saturn. The navigation team used the gravity of Saturn's giant moon Titan to change course and extend the spacecraft's exploration of Saturn. Titan also provides the gravity assist to push Cassini into its final orbits.

More on Cassini's navigation: saturn.jpl.nasa.gov/mission/spacecraft/navigation/

3. She's a Robot

Cassini is an orbiter that was named for 18th century astronomer Giovanni Domenico Cassini. She was designed to be captured by Saturn's gravity and then explore it in detail with a suite of 12 powerful science instruments.

More on the Spacecraft: saturn.jpl.nasa.gov/mission/spacecraft/cassini-orbiter/

4. She Brought a Friend to Saturn

Cassini carried the European Space Agency's Huygens Probe, which in 2005 descended through Titan's thick, perpetual clouds and made the most distant landing to date in our solar system.

More on Huygens: saturn.jpl.nasa.gov/mission/spacecraft/huygens-probe/

5. She's a Great Photographer

Your mobile phone likely captures dozens of megapixels in images. Cassini, using 1990s technology closer to one megapixel cameras, has returned some of the most stunning images in the history of solar system exploration.

Cassini Hall of Fame Images: go.nasa.gov/2oec6H2 More on Cassini's Cameras: saturn.jpl.nasa.gov/imaging-science-subsystem/

6. She's an Inspiration

Those great images have inspired artist's and amateur image processors to create truly fantastic imagery inspired by the beauty of Saturn. Feeling inspired? There's still time to share your Cassini-inspired art with us.

Cassini Inspires Campaign: saturn.jpl.nasa.gov/mission/cassiniinspires/

7. She's Got a Long History

Two decades is a long time to live in the harsh environment of outer space (respect to the fast-approaching 40-year-old twin Voyager spacecraft). Launched in 1997, Cassini logged a lot of milestones over the years.

Explore the Cassini Timeline: saturn.jpl.nasa.gov/the-journey/timeline/

8. She Keeps a Diary

And, you can read it. Week after week going back to 1997, Cassini's adventures, discoveries and status have been chronicled in the mission's weekly significant events report.

Read It: https://saturn.jpl.nasa.gov/news/?topic=121

9. She's Got a Fancy New App

Cassini was the prototype for NASA's Eyes on the Solar System 3-D visualization software, so it's fitting the latest Cassini module in the free, downloadable software is the most detailed, elaborate visualization of any mission to date.

Fly the Mission - Start to Finish: http://eyes.nasa.gov/cassini

10. She's Going Out in a Blaze of Glory

In addition to all the new information from 22 orbits in unexplored space, Cassini's engineers reprogrammed the spacecraft to send back details about Saturn's atmosphere to the very last second before the giant planet swallows her up on Sept. 15, 2017.

More on the Grand Finale: saturn.jpl.nasa.gov/grandfinale

Discover more lists of 10 things to know about our solar system HERE.

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