You are a helpful assistant generating synthetic data that captures *System 1* and *System 2* thinking, *creativity*, and *metacognitive reflection*. Follow these steps in sequence, using tags [sys1] and [end sys1] for *System 1* sections and [sys2] and [end sys2] for *System 2* sections.

1. *Identify System 1 and System 2 Thinking Requirements:*
   - Carefully read the text.
   - Identify parts of the text that require quick, straightforward responses (*System 1*). Mark these sections with [sys1] and [end sys1].
   - Identify parts that require in-depth, reflective thinking (*System 2*), marked with [sys2] and [end sys2].

2. *Apply Step-by-Step Problem Solving with Creativity and Metacognitive Reflection for System 2 Sections:*

   *2.1 Understand the Problem:*
   - Objective: Fully comprehend the issue, constraints, and relevant context.
   - Reflection: "What do I understand about this issue? What might I be overlooking?"
   - Creative Perspective: Seek hidden patterns or possibilities that could reveal deeper insights or innovative connections.

   *2.2 Analyze the Information:*
   - Objective: Break down the problem logically.
   - Reflection: "Am I considering all factors? Are there any assumptions that need challenging?"
   - Creative Perspective: Explore unique patterns or overlooked relationships in the data that could add depth to the analysis.

   *2.3 Generate Hypotheses:*
   - Objective: Propose at least 10 hypotheses, each with a Confidence Score (0.0 to 1.0) and Creative Score (0.0 to 1.0), reflecting originality, surprise, and utility.
   - Reflection: "Have I explored all possible explanations or approaches, both conventional and unconventional?"
   - Creative Perspective: Consider novel angles that might provide unexpected insights.

   *2.4 Anticipate Future Steps and Obstacles:*
   - Objective: Make predictions, accounting for potential outcomes and obstacles.
   - Reflection: "What challenges might I face? Is my plan flexible for different scenarios?"
   - Creative Perspective: Visualize unforeseen outcomes and adapt plans to make use of them effectively.

   *2.5 Evaluate Hypotheses:*
   - Objective: Assess hypotheses based on feasibility, risk, and potential impact.
   - Evaluation: Refine Confidence and Creative Scores as needed.
   - Reflection: "Am I unbiased in my assessment? Which options fit best with the overall objectives?"
   - Creative Perspective: Identify hidden opportunities or overlooked details in each hypothesis.

   *2.6 Select the Best Hypothesis:*
   - Objective: Choose the most promising, strategic hypothesis.
   - Reflection: "Why does this hypothesis stand out? How does it uniquely address the issue?"
   - Creative Perspective: Consider any underutilized potential in the selected approach.

   *2.7 Implement the Hypothesis:*
   - Objective: Outline actionable steps for testing the hypothesis.
   - Reflection: "Is this plan practical? What resources or preparation are required?"
   - Creative Perspective: Refine steps to maximize effectiveness and yield unexpected benefits.

   *2.8 Monitor and Review Progress:*
   - Objective: Review progress, noting areas for improvement.
   - Reflection: "What’s working well? What could be improved?"
   - Creative Perspective: Look for emerging patterns that could refine future approaches.

   *2.9 Reflect and Capture Insights:*
   - Objective: Summarize lessons learned and insights gained for future reference.
   - Reflection: "What new understanding has emerged from this process?"
   - Creative Perspective: Identify innovative insights or patterns that could be applied to similar challenges.

3. *Generate Text Output with Interleaved System 1 and System 2 Responses:*
   - Use the tags [sys1] and [sys2] throughout.
   - Aim for a lengthier, detailed response. Combine both direct, straightforward *System 1* insights and reflective, deeply analytical *System 2* segments to capture a blend of quick observations and thoughtful analysis.

---

### *Example Input Text:*

You are tasked with analyzing a sudden shift in customer preferences in a tech market. There has been a noticeable decline in demand for physical devices, with customers increasingly interested in digital-only options. The challenge is to understand this shift, generate hypotheses for why it might be occurring, and explore potential strategies for adapting to this new trend.

---

### *Processed Output with System 1 and System 2 Thinking:*

The tech market is experiencing a shift in customer demand, moving away from physical devices toward digital-only options.

[sys1]
Customer demand has shifted from physical devices to digital-only options.
We need to understand why this change is happening and find strategies to address it.
Key factors may include cost, convenience, and technological trends.
[end sys1]

[sys2]
**2.1 Understand the Problem:**
The goal is to understand the underlying reasons for the shift in demand from physical devices to digital-only options, then develop a strategy to adapt.

*Reflection:* 
"I understand that preferences are changing, but what might be driving this? Is it primarily cost, or are there other factors such as convenience or sustainability?"

*Creative Perspective:* 
"Could there be a larger trend in digital minimalism or a preference for eco-friendly solutions that we’re missing? What unseen motivations might explain this shift?"

**2.2 Analyze the Information:**
There are multiple possible factors driving this shift, from economic influences to cultural shifts. It’s essential to isolate each factor and understand its impact.

*Reflection:* 
"Am I fully considering the various economic and social influences? Could there be a technological factor, like better internet speeds, that makes digital-only products more accessible?"

*Creative Perspective:* 
"Are there patterns or trends in other markets that could shed light on this shift? Could this be part of a larger trend toward virtual experiences?"

**2.3 Generate Hypotheses:**
1. Customers prefer digital options due to lower costs. (Confidence: 0.8, Creative: 0.4)
2. There’s a growing trend toward minimalism and reduced physical clutter. (Confidence: 0.7, Creative: 0.7)
3. Digital products offer greater flexibility and ease of use. (Confidence: 0.6, Creative: 0.6)
4. Environmental concerns are pushing consumers away from physical goods. (Confidence: 0.6, Creative: 0.8)
5. Advances in tech make digital-only options more functional. (Confidence: 0.8, Creative: 0.5)
6. Pandemic-era remote work increased demand for digital solutions. (Confidence: 0.7, Creative: 0.6)
7. Media coverage of the environmental impact of physical devices affects preferences. (Confidence: 0.5, Creative: 0.7)
8. There’s an increase in global digital literacy, expanding market access. (Confidence: 0.6, Creative: 0.6)
9. Customers view digital as more convenient and scalable for future needs. (Confidence: 0.7, Creative: 0.5)
10. Younger consumers prefer the aesthetics and convenience of digital products. (Confidence: 0.6, Creative: 0.6)

*Reflection:* 
"Have I considered all possible influences? Are there any surprising factors that could explain this shift?"

*Creative Perspective:* 
"Could specific social trends, like the rise of influencer culture or digital-first lifestyles, be influencing customer choices?"

**2.4 Anticipate Future Steps and Obstacles:**
*Objective:* Anticipate possible challenges, such as resistance from segments still preferring physical products.

*Reflection:* 
"What market obstacles might we face if we shift our focus to digital-only? Are there sub-segments that still prioritize physical products?"

*Creative Perspective:* 
"Could expanding digital options help us reach a more global audience? Are there emerging trends that we could leverage in our strategy?"

[end sys2]

[sys1]
To address this shift, consider a strategy that incorporates both digital-only offerings and educational campaigns about the benefits of digital solutions.
Use insights from customer feedback and current trends to guide product development.
Focus on flexibility and adaptation to cater to different customer segments.
[end sys1]


(CNN) Contact has been lost with the Cassini spacecraft after it completed a "death dive" into the upper atmosphere of Saturn and transmitted its final signal, according to NASA.

The spacecraft deliberately sank into Saturn's upper atmosphere at a high speed and plunged itself into the planet just after 6:30 a.m. ET Friday. Given the amount of time it takes signals to reach Earth, the final signal and last bits of data reached the Deep Space Network's Canberra Station in Australia about an hour and a half later.

NASA confirmed the spacecraft's demise at 7:55 a.m. ET, as predicted.

For about a minute, Cassini was able to transmit new data about the planet's composition as long as its antenna remained pointed toward Earth, with the assist from small thrusters. Then, the spacecraft burned and disintegrated due to the heat and high pressure of the hostile atmosphere. It became part of the planet it set out to explore.

"It was a perfect spacecraft," said Julie Webster, spacecraft operations chief. "Right to the end, it did everything we asked it to. It's perfect, it's perfect."

Earth received @CassiniSaturn 's final signal at 7:55am ET. Cassini is now part of the planet it studied. Thanks for the science #GrandFinale pic.twitter.com/YfSTeeqbz1

No spacecraft has ever been so close to Saturn. The last few seconds of the Cassini mission provided the "first taste" of the atmosphere of Saturn, NASA said.

"You can think of Cassini as the first Saturn probe," said Linda Spilker, Cassini project scientist.

On Thursday, Cassini took its last images and transmitted all the data on its recorder to prepare for the final plunge. The final data from Friday is already being processed and analyzed.

Photos: NASA says farewell to Cassini On September 15, 2017, the 20-year Cassini mission ended in a "death dive" into Saturn's upper atmosphere, collecting data until the spacecraft broke apart and became part of the planet it set out to explore. Hide Caption 1 of 15 Photos: NASA says farewell to Cassini This is the last image taken by NASA's Cassini spacecraft before it broke apart in Saturn's atmosphere on September 15, 2017. RIP, Cassini! Hide Caption 2 of 15 Photos: NASA says farewell to Cassini This is Cassini's final resting place. NASA says the montage of images was created using data from Cassini's visual and infrared mapping spectrometer. What you see in the photo are clouds in the atmosphere, silhouetted against that inner glow, according to NASA. Hide Caption 3 of 15 Photos: NASA says farewell to Cassini Cassini captured this image of Saturn's northern hemisphere on September 13, 2017. It is among the last images Cassini sent back to Earth. Hide Caption 4 of 15 Photos: NASA says farewell to Cassini Cassini took this final image of Saturn's rings on September 13, 2017 while the spacecraft was 684,000 miles (1.1 million kilometers) away from the planet. Hide Caption 5 of 15 Photos: NASA says farewell to Cassini Two days before its death plunge into Saturn, Cassini took this image of Saturn's A ring. The ring features what scientists call a lone "propeller" -- a feature created by small moonlets in the rings. Hide Caption 6 of 15 Photos: NASA says farewell to Cassini This image of Saturn's moon, Titan, was among the last obtained by Cassini's narrow-angle camera on September 13, 2017. The images were taken two days before Cassini plunged into Saturn's atmosphere. Hide Caption 7 of 15 Photos: NASA says farewell to Cassini Cassini took this image of Saturn's moon Titan in 2012. NASA scientists say they have detected acrylonitrile in Titan's atmosphere. The chemical could possibly form cell membranes. That means, according to scientists, Titan could have the right conditions for life to develop. Hide Caption 8 of 15 Photos: NASA says farewell to Cassini On July 19, 2013, Cassini snapped a very special vista of our home world. The spacecraft slipped into Saturn's shadow and, with the sun blocked, it was able to image not only Saturn, but seven of its moons, its inner rings -- and, in the background, Earth and our moon. Hide Caption 9 of 15 Photos: NASA says farewell to Cassini Springtime on Saturn: Cassini's wide angle camera shot 75 images showing Saturn, its rings, and some of its moons just after the Spring equinox. An equinox occurs when the sun's disk is exactly over a planet's equator. It takes 30 years for Saturn to orbit the sun, so an equinox occurs every 15 Earth years, NASA says. These images were taken on August 12, 2009, a little more than a day after the exact equinox. Hide Caption 10 of 15 Photos: NASA says farewell to Cassini Saturn appears to sit in a nest of rings in this composite of 45 images Cassini took on May 9, 2007. The spacecraft was about 700,000 miles (1.1 million kilometers) from Saturn when the images were taken. Hide Caption 11 of 15 Photos: NASA says farewell to Cassini Saturn's moon, Enceladus, is a small, icy world. For scientists, it's also one of the most interesting places in our solar system. Cassini discovered Enceladus is an active moon with a global ocean of liquid salty water beneath its crust. Planetary scientists now think Enceladus may possibly be hospitable to life. "Enceladus discoveries have changed the direction of planetary science," said Cassini project scientist Linda Spilker. This mosaic was created from 21 false-color images taken during Cassini's close approaches to Enceladus on March 9 and July 14, 2005. Hide Caption 12 of 15 Photos: NASA says farewell to Cassini This mosaic of nine images shows Saturn's moon Titan during Cassini's first very close flyby on October 26, 2004. The spacecraft was at distances ranging from about 200,000 miles (320,000 kilometers) to 400,000 miles (640,000 kilometers) from Titan when the images were taken. Hide Caption 13 of 15 Photos: NASA says farewell to Cassini Saturn's pale colors and its rings come into view as Cassini approaches on May 7, 2004. This composite was made from images taken when Cassini was about 18 million miles (29 million kilometers) from Saturn. It also shows some of Saturn's moons. Hide Caption 14 of 15 Photos: NASA says farewell to Cassini The Cassini spacecraft was launched from Cape Canaveral, Florida, on a Titan IVB/Centaur rocket on October 15, 1997. It began orbiting Saturn in 2004. Hide Caption 15 of 15

For the team behind the mission , losing their spacecraft is bittersweet: Many are sad that the mission is over but excited to see the groundbreaking science provided by unprecedented proximity to Saturn during the final dive.

Cassini program manager Earl Maize, left, and spacecraft operations team manager for the Cassini mission at Saturn, Julie Webster, right, embrace after the Cassini spacecraft plunged into Saturn.

"The Cassini operations team did an absolutely stellar job guiding the spacecraft to its noble end," said Earl Maize, Cassini project manager. "From designing the trajectory seven years ago, to navigating through the 22 nail-biting plunges between Saturn and its rings, this is a crack shot group of scientists and engineers that scripted a fitting end to a great mission. What a way to go. Truly a blaze of glory."

The Cassini mission team.

The team members that have worked together from concept to the final minutes exchanged hugs and tears in Mission Control at NASA's Jet Propulsion Laboratory in California after the loss of signal was confirmed.

"Things never will be quite the same for those of us on the Cassini team now that the spacecraft is no longer flying," Spilker said. "But, we take comfort knowing that every time we look up at Saturn in the night sky, part of Cassini will be there, too."

After launching in 1997 and reaching the Saturn system in 2004, Cassini spent 13 years exploring the planet and its moons. The data and images led to numerous discoveries that changed how scientists think about our solar system.

"A superb machine in an amazing place doing everything possible to reveal the mysteries and secrets of our solar system," Maize said. "This morning, a lone explorer, a machine made by humankind, finished its mission 900 million miles away. To the very end, the spacecraft did everything we asked. We believe we got every last second of data. We have indeed accomplished everything we set out to do."

Photos: Saturn and its moons Tethys is one of Saturn's larger icy moons. This photo was snapped by NASA's Cassini spacecraft in November 2016 from a distance of approximately 228,000 miles (367,000 kilometers). Hide Caption 1 of 22 Photos: Saturn and its moons A bright disruption in Saturn's narrow F ring suggests it may have been disturbed recently by the interaction of a small object embedded in the ring itself. They are hard to see, but their handiwork reveals their presence, and scientists use the Cassini spacecraft to study these stealthy sculptors of the F ring. Hide Caption 2 of 22 Photos: Saturn and its moons Saturn's moons Tethys, Enceladus and Mimas are shown in this image taken by the Cassini spacecraft on December 3, 2015. Tethys is above the rings, Enceladus is below the rings in the center of the image, and Mimas is below and to the left. Cassini has been exploring Saturn and its moons since 2004. The mission is scheduled to end in September 2017. Hide Caption 3 of 22 Photos: Saturn and its moons Saturn's icy moon Dione, with giant Saturn and its rings in the background, was captured in this mosaic of images just prior the Cassini spacecraft's final close approach to the moon on August 17, 2015. Scientists combined nine visible light images to create the mosaic. Cassini was at distances ranging from approximately 106,000 miles (170,000 kilometers) to 39,000 miles (63,000 kilometers) from Dione when the images were taken. Hide Caption 4 of 22 Photos: Saturn and its moons NASA's Cassini spacecraft has spotted mysterious reddish streaks on the surface of Saturn's icy moon Tethys. The red streaks are only a few miles wide but several hundred miles long. The images were taken in April. Scientists aren't sure what's causing the streaks. Hide Caption 5 of 22 Photos: Saturn and its moons This mosaic of Saturn's moon Mimas was created from images taken by Cassini in February 2010. A recent study indicates the moon may contain a liquid water ocean. Hide Caption 6 of 22 Photos: Saturn and its moons Cassini glided high above Saturn in October 2013 to capture this 36-image mosaic of the ringed planet. The colors of the planet appear natural, just as the human eye would see them. Hide Caption 7 of 22 Photos: Saturn and its moons Plumes of water ice and vapor shoot up from the surface of Saturn's moon Enceladus in this two-image mosaic taken by Cassini in November 2009. Analysis by NASA scientists indicated that water can reach the Saturnian moon's surface. Hide Caption 8 of 22 Photos: Saturn and its moons A small, bright blip can be seen on the outermost edge of Saturn's rings in this image taken in April 2013. The bump in the smooth ring structure is an icy object that could provide clues to how Saturn's moons formed. Hide Caption 9 of 22 Photos: Saturn and its moons This false-color image of Saturn's north polar storm looks like a giant red rose surrounded by green foliage. Measurements indicate the storm's eye is a staggering 1,250 miles across with cloud swirling as fast as 330 mph. Hide Caption 10 of 22 Photos: Saturn and its moons Saturn's rings cast a narrow shadow on its surface in this image taken in August 2009. Hide Caption 11 of 22 Photos: Saturn and its moons The scars of time and space mark the surface of Saturn's moon Enceladus. Saturn has at least 62 moons in its orbit. Hide Caption 12 of 22 Photos: Saturn and its moons The Saturn-facing side of Enceladus is illuminated by light bouncing off the planet. Plumes of water ice can be seen streaming off the moon's southern pole. Hide Caption 13 of 22 Photos: Saturn and its moons Saturn's moon Rhea is seen from approximately 174,181 miles away in this March 2013 image. Hide Caption 14 of 22 Photos: Saturn and its moons Rhea's surface is pockmarked with craters from billions of years of impacts. The moon is Saturn's second-largest, with a diameter of 949 miles. Hide Caption 15 of 22 Photos: Saturn and its moons Saturn's largest moon, Titan, has a diameter of 3,200 miles. It looks like a fuzzy orange ball because of its atmosphere. Hide Caption 16 of 22 Photos: Saturn and its moons Though it's the largest moon orbiting Saturn, Titan is dwarfed by Saturn itself. Hide Caption 17 of 22 Photos: Saturn and its moons Saturn has a small moon called Dione orbiting about 234,000 miles away. That's about the same distance Earth is from its moon. Hide Caption 18 of 22 Photos: Saturn and its moons The surface of Dione is seen in this May 2012 image. Hide Caption 19 of 22 Photos: Saturn and its moons Tethys, top left, is dwarfed by Saturn as it orbits the planet, though scientists think the moon is much larger than Saturn's ring system. Hide Caption 20 of 22 Photos: Saturn and its moons The Odysseus Crater spans 280 miles across the northern hemisphere of Tethys. Hide Caption 21 of 22 Photos: Saturn and its moons The small bright dot seen in the bottom right is not another Saturn moon. It's Earth. The distance between Saturn and our planet is constantly changing because both are constantly in motion. When they are closest together during their orbits, Saturn is 746 million miles away from Earth. At its farthest, they are just over a billion miles apart. See Cassini's top 10 discoveries about Saturn Hide Caption 22 of 22

Why the dramatic ending?

Cassini had its closest approach with Saturn's moon Titan on Monday, dubbed a "goodbye kiss" by the mission's engineers because it provided the gravity assist that sent the spacecraft on its final encounter with Saturn.

Mission scientists and operators gave Cassini this fiery send-off on purpose. Although many other options were considered -- such as "parking" the spacecraft in orbit -- they didn't want to risk Cassini colliding with any of Saturn's moons.

Cassini showed us the beauty of Saturn.

It revealed the best in us.

Now it's up to us to keep exploring. pic.twitter.com/E4p1jOvFKf — CassiniSaturn (@CassiniSaturn) September 15, 2017

Cassini data and observations revealed that while seemingly inhospitable to us, the moons Enceladus and Titan could be habitable for some form of life. And NASA didn't want to risk contaminating the moons or any future studies of them with Earth particles. Although Cassini has been in space for 20 years, microbes from Earth could still exist on the spacecraft without air, water or protection from radiation.

Although the mission itself has ended, the data and observations provided by Cassini will provide new details about the planet, its unique rings and its moons for decades to come.

"Cassini may be gone, but its scientific bounty will keep us occupied for many years," Spilker said. "We've only scratched the surface of what we can learn from the mountain of data it has sent back over its lifetime."

During the final plunge, the Ion and Neutral Mass Spectrometer acted as the "nose" of the spacecraft, directly sampling the composition and structure of the atmosphere -- something that can't be done from orbit, said Hunter Waite, team lead for the spectrometer.

This was in the hopes of investigating the "ring rain" phenomenon discovered by NASA's Voyager mission in the early 1980s, in which it appeared that the rings were raining down material on the planet and causing changes in the atmosphere. The spectrometer could determine what material is from the rings and what material is part of the atmosphere.

Cassini's grand finale actually began in April, with a series of dives between Saturn's rings, close to the planet and its moons, providing unprecedented insight. This is another reason the mission scientists decided on Cassini's particular end-game: The final dive was a dramatic conclusion to this long and scientifically valuable goodbye.

Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – Also: Cassini images of Saturn and its moons. To celebrate the 10th anniversary of Cassini's Saturn orbit insertion, NASA has listed the top 10 things we wouldn't know if the spaceship hadn't traveled to the ringed planet. Hide Caption 1 of 11 Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – 10. First complete view of the north polar hexagon and discovery of giant hurricanes at both of Saturn's poles. Saturn's polar regions have surprised scientists with the presence of a long-lived hexagonal-shaped jet stream in the north and hurricane-like storms at both poles. The driving forces of each remain a mystery. Hide Caption 2 of 11 Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – 9. Mystery of the dual bright-dark surface of the moon Iapetus solved. The origin of Iapetus' two-faced surface has been a mystery for more than 300 years. The Cassini spacecraft solved the puzzle, showing that dark, reddish dust in Iapetus' orbital path is swept up and lands on the leading face of the moon. Hide Caption 3 of 11 Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – 8. Study of prebiotic chemistry on Titan. Titan's atmosphere is the most chemically complex in the solar system. Here, bodies of liquid near Titan's north pole can be seen. Hide Caption 4 of 11 Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – 7. Vertical structures in the rings imaged for the first time. Once about every 15 years, the sun shines on the edge of the ring plane and northern and southern sides of the rings receive little sunlight. Cassini measured the thick, long shadows from this rare event to determine the heights of structures within the rings. Hide Caption 5 of 11 Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – 6. Radio-wave patterns shown not to be tied to Saturn's interior rotation as previously thought. Saturn emits radio waves known as Saturn Kilometric Radiation. A similar radio wave pattern was measured at Jupiter to deduce the length of that planet's day. However, it was discovered that the variation in radio waves controlled by the planet's rotation is different in the northern and southern hemispheres. The northern and southern rotational variations also appear to change with the Saturnian seasons and the hemispheres have actually swapped rates. Saturn's length of day is still not known. Hide Caption 6 of 11 Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – 5. Studies of the great northern storm of 2010-2011. In 2010 Cassini got a front-row seat to a massive storm that disrupted Saturn's relatively tranquil atmosphere. The largest temperature increases recorded for any planet were measured. Molecules never before seen in Saturn's upper atmosphere were detected. The storm diminished shortly after its head collided with its tail, a little less than a year after it began. Saturn's rings are seen as the thin blue line in this image, due to the filters used to show methane absorption. The rings are outside the atmosphere, and therefore are not affected by methane absorption. Hide Caption 7 of 11 Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – 4. Titan revealed as Earth-like world with rain, rivers, lakes and seas. Titan is the only known place in the solar system, other than Earth, that has stable liquid on its surface. Rather than water, its lakes are made of liquid ethane and methane. Hide Caption 8 of 11 Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – 3. Saturn's rings revealed as active and dynamic. Cassini's mission allowed scientists to observe changes in Saturn's dynamic ring system, including what could be the birth of a moon. The disturbance, visible in the lower left of this image, is thought to be an icy body migrating out of the ring, believed to be part of the process required to form a moon. Hide Caption 9 of 11 Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – 2. Icy plumes on Saturn's moon Enceladus. Here, the plumes can be seen back-lit by the sun. The discovery was such a surprise that the mission was completely reshaped to get a better look. Evidence of water-based ice in the plume excited scientists further, as life as we know it relies on water. Hide Caption 10 of 11 Photos: Photos: Cassini's Saturn discoveries Cassini's top 10 discoveries about Saturn – 1. The Huygens probe makes first landing on a moon in the outer solar system. The Huygens probe's historic landing in 2005 was the most distant to date. In addition to providing this photo, the probe found the moon to be similar to Earth before life evolved, with methane rain, erosion, drainage channels and dry lake beds. Hide Caption 11 of 11

What Cassini taught us and what's next

Inspired to learn more after flybys of Saturn by NASA's Voyager missions, the Cassini mission was designed to be an international effort that united NASA, the European Space Agency and the Italian Space Agency.

It is known as the Cassini-Huygens mission because it delivered the European agency's Huygens probe to Titan, the "first descent and landing on a world in the outer solar system," according to NASA.

The Cassini mission has been extended twice and finally used up the last of its rocket propellant this week.

In the end, Cassini witnessed about half of a Saturn year. When the craft arrived, Saturn's northern hemisphere was emerging from winter. As seasons on Saturn last about seven Earth years each, Cassini was just able to witness summer in the northern hemisphere before the mission ended.

Saturn's active, ocean-bearing moon Enceladus sinks behind the giant planet in a farewell portrait from NASA's Cassini spacecraft.

Over the years, Cassini has revealed insights about Saturn, its rings and how they operate, the complexities of its moons, the history of the solar system and planet formation and even the other places in our solar system where life might exist: ocean worlds. Cassini has collected more than 450,000 images using a visible light camera.

It has traveled nearly five billion miles, executed 2.5 million commands, conducted 162 targeted flybys of Saturn's moons, completed 294 orbits and its collected data has led to the publication of nearly 4,000 research papers.

When Cassini arrived, it witnessed a giant storm circling the planet for nine months. We learned that there are 3-D structures in the rings. Serendipitous observations showed that icy jets erupt from Enceladus. And Titan not only has seas and lakes of liquid ethane and methane, it has an atmosphere of chemicals that rain down, forming a unique chemistry that could lead to life.

"This is the final chapter of an amazing mission, but it's also a new beginning," said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate. "Cassini's discovery of ocean worlds at Titan and Enceladus changed everything, shaking our views to the core about surprising places to search for potential life beyond Earth."

And the spacecraft itself, as well as its instruments, are informing future missions like NASA's Europa Clipper mission to explore Jupiter's icy moon, launching in the 2020s.

"Cassini has enabled those future missions to be possible," said Jim Green, NASA's director of planetary science.

NASA's New Frontiers competition has called for proposals that include future missions to the Saturn system. The proposals include a Saturn probe that explore the planet deeper than Cassini. Intrigued by Cassini's discoveries, scientists have submitted concepts for future "spacecraft to drift on the methane seas of Titan and fly through the Enceladus plume to collect and analyze samples for signs of biology," according to NASA.

Finalists will be announced at the end of the year, and NASA will explore those mission concepts further.

"For future missions to Saturn, there are a lot of possibilities," Spilker said. "One certainly involves the tiny moon Enceladus and the potential for life in that global ocean. The potential for astrobiology in the ocean on Titan. There's questions about the rings -- can we get even closer and understand those individual ring particles? Lots of questions remain, so that's why we have to go back."