On September 15, 2017, the Cassini spacecraft burned up in Saturn's atmosphere. This event united space lovers all over the Earth. Cassini was not just any satellite. He served as one of the main symbols of space research, and science in general. The same symbol as the Hubble telescope or the Large Hadron Collider.

Cassini was launched back in 1997. Just imagine - this is the year Titanic, Quake 2 and the first Fallout were released. During the work of Cassini, an entire generation grew up. Many modern astronomy lovers became interested in space thanks to Cassini. Therefore, today we remember the history of the mission and pay it the tribute it deserves.

From concept to launch pad

In 1980–1981, the pair made a historic flyby of Saturn. They took the first detailed photographs of the planet, its rings and satellites, and analyzed the atmosphere and magnetic field. The results amazed astronomers. It turned out that Saturn's rings consist of hundreds of thin rings forming a complex system. Titan, Saturn's largest satellite, was obscured by a layer of hydrocarbon haze that was opaque in the visible spectrum. The satellite Iapetus looked as if the designer of the solar system had forgotten to paint it: one of its hemispheres shone brightly, like fresh snow, the other was black, like soot.

Cassini assembly

The Voyagers were physically unable to stay near the planet and study it longer. To unravel the mysteries of Saturn and its moons, a fundamentally different mission was required. A device that could go into orbit around the planet and explore it for several years.

In 1982, scientists from NASA and ESA began the first consultations about a joint long-duration mission to the Saturn system. It would consist of an orbiter and a lander that would land on Titan and see what was happening on its surface. The mission was named after Giovanni Cassini, the famous 17th-century astronomer who discovered the four moons of Saturn and the gap in its rings.

The negotiations were not easy. At that time, relations between NASA and ESA were complicated by the cancellation of a number of joint projects. But in 1988, the partners finally agreed on the distribution of responsibilities. NASA was supposed to build the Cassini orbiter, ESA was supposed to build the Huygens descent probe for Titan. It was named after Christiaan Huygens, who discovered the rings of Saturn and Titan itself.

Model of the Huygens apparatus

Cassini's problems didn't end there. The total budget of the project exceeded three billion dollars (80% of the funds were allocated by NASA), and the American Congress has repeatedly threatened to deprive the project of funding. Even at NASA, not everyone supported the mission. But Cassini survived, thanks in no small part to the efforts of ESA lobbyists. Things even went as far as letters to US Vice President Al Gore asking him not to close the program. As a result, although with difficulty, the mission received the necessary funding.

The latest threat to Cassini is the green ones. Shortly before the launch, environmental activists began demonstrations at Cape Canaveral and filed a lawsuit demanding a ban on the launch. Cause? 32 kilograms of plutonium-238 on board the station. The fact is that the vicinity of Saturn reaches 100 times less sunlight than Earth. Therefore, to generate energy, Cassini was equipped with a radioisotope generator.

Environmental activists stated that in the event of an accident there would be radioactive contamination and demanded to “save the Earth” from Cassini. And no matter how much NASA experts explained that even in the event of an accident the plutonium would remain in a protected container, this could not convince the “greens.” Fortunately, the court did not take into account the environmental horror stories and did not cancel the launch.

Launch of the Centaur rocket with Cassini on board

Seven years in flight

Cassini launched on October 15, 1997 and headed towards... Venus. There is no mistake here. The mass of the station was almost six tons, which made it one of the largest interplanetary vehicles in history: only the Soviet Phobos weighed more. The rocket's power was not enough to send such a colossus directly to Saturn. So engineers took advantage of gravity. Cassini flew by Venus twice, then Earth, and finally Jupiter. These gravity maneuvers allowed the vehicle to achieve the required speed.

Flying past Jupiter, Cassini managed to study this gas giant. He discovered several new storms in its atmosphere and took the highest quality photographs of the planet at that time. At the same time, engineers checked the functionality of the station’s instruments.

"Portrait" of Jupiter made from several Cassini photographs

In the early summer of 2004, Cassini reached the vicinity of Saturn. On June 11, the craft passed Phoebe, one of the planet's most distant satellites, which orbits nearly 13 million kilometers from the gas giant (that's 36 times the distance between the Earth and the Moon). Cassini had only one chance to visit this unusual moon, and its trajectory was specifically designed for a close flyby.

On July 1, Cassini performed an extremely difficult maneuver, on the outcome of which the fate of the entire mission depended. It was successful. Cassini turned on its main engine for 96 minutes and slowed down so that the planet's gravity could pick it up. So it became the first artificial satellite of Saturn in history.

This is how Cassini saw Saturn

Thirteen years for Saturn

"I've seen things you humans wouldn't believe..." If Cassini could talk, it would definitely quote Blade Runner. From the very beginning of its operation, the device began to make discoveries, one more incredible than the other. For those who love statistics, let's say that during the 13 years of its stay at Saturn, the station took about 400 thousand photographs and sent over 600 gigabytes of information to Earth. Based on their results, about 4,000 scientific articles have already been written - and this number will grow, because Cassini data will be analyzed for many years to come. To describe all the achievements of the mission, a whole collection of essays would be required. We will only briefly mention the main milestones.

One of the mission's priority targets was Titan. In January 2005, the Huygens probe separated from Cassini and made a historic landing on its surface. The Huygens images showed complex terrain with areas resembling river beds and coastlines. Photographs from the surface show rounded stones with traces of liquid exposure.

Titan from both sides in the Cassini photo

Subsequently, Cassini completed over a hundred flybys of Titan. The device scanned the surface of the satellite with a radar, and shooting in the infrared range made it possible to look under its haze. It turned out that Titan has lakes, rivers, seas and even rains. But not from water, but from liquid hydrocarbons - a mixture of ethane and methane. The temperature on Titan is such that these substances can exist in three states at once (liquid, gas, solid) and perform the same role that water plays on our planet. This is the only body in the solar system besides the Earth where there is a full fluid cycle, and permanent bodies of water exist on the surface. More precisely, hydrocarbons.

Huygens landing on Titan, concept art

Recording of atmospheric wind on Titan made by Huygens during landing

Overall, conditions on Titan closely resemble early Earth in the pre-oxygen era. The satellite turned out to be a kind of time machine: it made it possible to study the processes that could lead to the emergence of life on our planet. Some scientists even make cautious assumptions that, despite the low temperatures, the simplest forms of life may already exist on Titan.

Mercator Plateau photographed by Huygens

Video of landing based on photographs from the device

But in the Saturn system there was an even more attractive target for astrobiologists - Enceladus. Before the Cassini mission, it was considered simply one of Saturn's many icy moons of little interest. But after Cassini’s first visit to Enceladus, these ideas had to be radically revised.

Enceladus, planet of giant geysers

It turned out that, despite its relatively small size (the diameter of the satellite is 520 kilometers, almost six times smaller than that of the Moon), Enceladus is one of the most geologically active bodies in the Solar System. Its south pole is densely dotted with geysers that constantly emit water into space. This water forms a separate ring around Saturn. The discovery of Enceladus geysers has become a scientific sensation. The Cassini program was urgently changed, and in subsequent years the device visited the satellite more than once. Several times Cassini flew directly through its emissions, analyzing their chemical composition.

Geysers of Enceladus

Data collected by Cassini showed that beneath Enceladus's icy surface lies a global ocean of liquid water. Its depth is estimated at 10 kilometers, the thickness of the ice above it ranges from 2 to 30 kilometers. Chemical analysis of the ejected water revealed salts, organic compounds and substances in it, indicating that active hydrothermal processes are taking place in the ocean of Enceladus. Now this satellite is considered the most suitable place for life in the solar system outside of Earth.

Cassini was able to solve the mystery of the “underpainted” Iapetus. It turned out that the differences in the color of the satellite are due to dust: meteorite impacts knock it out from the distant moons of Saturn, and it settles on the leading hemisphere of Iapetus (this is the hemisphere with which it moves “forward” in its orbit). Dust-covered areas heat up more than neighboring regions. As a result, ice evaporates from them and condenses where the surface temperature is lower: on the trailing side and in the circumpolar regions. A positive feedback is formed: dark areas become even darker, and vice versa.

Cassini also discovered another unique feature of Iapetus - the ring-shaped mountain range "Wall of Iapetus" that stretches along its equator. The unusual formation has a height of up to 13 kilometers, a width of up to 20 kilometers and a total length of about 1,300 kilometers. According to one theory, Iapetus once had a ring, and its particles fell to the surface and formed a wall.

Black and white Iapetus in Cassini images

But, of course, Cassini studied not only the satellites of Saturn, but also the planet itself. Over the years of the mission, the device captured several changes of seasons. They manifested themselves especially clearly in the hexagon - this is the name given to the amazing hexagonal-shaped vortex located at the north pole of the planet. The width of this formation is 25 thousand kilometers, approximately two diameters of the Earth. Cassini recorded how, with the arrival of summer in the northern hemisphere of Saturn, the hexagon changed color from dark blue to golden. The intensity of ultraviolet radiation increased, this triggered photochemical reactions, and compounds (tholins) began to be synthesized at the north pole, which changed the color of the storm.

Saturn's hexagonal vortex in 2016

Cassini has photographed Saturn's ring system many times. The images demonstrated their extraordinary complexity and variability. Numerous satellites of Saturn exert their gravity on the rings of the planet, which is why vortices, waves, kinks, loops and other structures are formed in them. Some small moons orbit directly within the rings. Their gravity accelerates the particles of the rings, which is why ruptures form in them. Other satellites play the role of “shepherds”. For example, the orbits of Prometheus and Pandora pass inside and outside the F ring. The gravity of a pair of satellites holds the particles of the rings in the same orbit, preventing them from scattering in different directions.

The highest quality photo of Saturn's rings

We must not forget about Cassini’s goal of popularizing space research. It turned out to be easy. Saturn is perhaps the most beautiful planet in the solar system, and its photographs have probably inspired many people to connect their lives with space.

One of Cassini's most famous images was taken on July 19, 2013. On that day, the device performed panoramic photography of the planet and its surroundings. At the time of photography, the Sun was exactly behind Saturn, effectively highlighting its rings. One of the pictures also showed our planet. From a distance of 1.5 billion kilometers, it appears as a pale blue dot.

“The Day the Earth Smiled”: the famous photo underwent extensive color correction to make the planets more visible. The earth is a barely noticeable point on the lower right under the rings

Cassini's final adventure

Cassini is often called the ideal space mission. The device operated well beyond its nominal four-year lifespan and completed all tasks without major incident. But, alas, any technology has a factor that limits its operating time. In the case of Cassini, these were the fuel reserves necessary for course corrections. Without it, control of the device would have become impossible. An uncontrolled station could crash into one of Saturn's moons and carry terrestrial microbes there. To exclude such a scenario, NASA decided to burn Cassini in the planet’s atmosphere.

But before this, the device had to survive the final adventure - 20 orbits at the outer edge of Saturn's rings, and then another 22 orbits between the planet's atmosphere and the inner edge of its rings. No vehicle has ever dived into this gap. The maneuver was considered very dangerous, but since the mission was already close to completion, NASA decided to take the risk.

Artist's impression of Cassini's final flight

As before, Cassini brilliantly completed all its tasks. He collected data that should solve the main mystery of Saturn - the age and origin of its rings. According to one version, they formed along with the planet. According to another, the rings are much younger and appeared as a result of the recent (by cosmic standards) destruction of one of Saturn’s moons. Cassini data will be analyzed for many more months, but preliminary results so far speak in favor of the second version.

Cassini had one last task to complete. During re-entry, the vehicle used thrusters to keep its antenna pointed at Earth for as long as possible. Already falling apart, Cassini still continued to transmit data on the composition of the gas envelope and the magnetic field of Saturn. Even here, the device managed to exceed the target, surviving in such extreme conditions 30 seconds longer than the simulations predicted. At 11 hours 55 minutes 46 seconds universal time, NASA's deep space communications complex in Canberra received the last signal from Cassini. By that time, the device itself had already disintegrated into fragments and turned into a flaming meteor.

NASA said goodbye to Cassini without mourning. Still, this is not a disaster, but the end of a successful mission (NASA/Joel Kowsky)

The ending of the mission evoked conflicting emotions: pride, admiration, sadness and emptiness. Cassini has been in operation for so long that it is difficult to remember a time when it was not there. You can imagine what the mission participants, who had been working on the project since the 1980s, experienced as they watched the device’s signal disappear.

It becomes even sadder when you realize that you will have to wait at least a decade for the next such expedition to the distant planets of the solar system. Unfortunately, space exploration is a slow business, and there is no mission on the horizon comparable to Cassini's ambition. One can only be consoled by the fact that many new discoveries will be made based on the data collected by the station.

Cassini's legacy will live on for a very long time. The photographs he took of Saturn and its moons will remain with us forever. Thanks to Cassini, we were able to see in all their glory these cosmic bodies that were previously just dots in the sky for us.

Clouds over Saturn. Photo: NASA/JPL-Caltech/Space Science Institute

NASA announced the termination of its 20-year mission to explore Saturn. The Cassini probe (named after the Italian astronomer Giovanni Cassini - ed.) sank into the planet's atmosphere and burned up. The last signal from the device lasted 83 minutes and reached the Earth at 14:55 Moscow time.

The Cassini-Huygens mission began in 1982 and was developed by a joint working group of the US National Academy of Sciences and the European Science Foundation. In October 1997, the device was launched from Cape Canaveral. The device spent almost 13 years in Saturn orbit, during which time it transmitted 635 gigabytes of data and 453 thousand images to the ground.

The spacecraft reached the orbit of the planet only in 2004, having previously made maneuvers around Venus, Earth and Jupiter. It was previously planned that the mission would end in 2008, but it was decided to extend it until 2010. The final decision to end the mission was made in 2017 due to a lack of fuel.

One of the most important achievements of the mission was the landing of the Huygens probe on Titan (the largest moon of Saturn - ed.) January 14, 2005. The device studied the atmosphere of the satellite.

Methane clouds over Titan. Photo: NASA/JPL-Caltech/Space Science Institute

The probe took photographs of Saturn's rings, which are made of ice and dust particles. It is still not known when they formed and why. Cassini images helped scientists discover a new ring of Saturn - the Janus-Epimetheus ring. The device studied the previously unknown satellites of the planet - Polydeuces, Pallene, Methona, Antha, Aegeon and Daphnis.

Photo: NASA/JPL-Caltech/Space Science Institute Cassini image shows the wave structure of Saturn's rings, taken June 4, 2017. Photo: NASA/JPL-Caltech/Space Science Institute
Photo: NASA/JPL-Caltech/Space Science Institute

The device also studied another satellite of Saturn, Enceladus. From the Cassini images, it was clear that the satellite had 250-kilometer plumes of water gushing from ice fractures on the surface of the satellite. Scientists have found that under the ice there is an ocean 45 kilometers deep. The thickness of the ice can reach from two to twenty kilometers.

Enceladus. Photo: NASA/JPL-Caltech/Space Science Institute

In 2015, Cassini performed its most dangerous maneuver yet—flying through the plumes of Enceladus. Thanks to this, scientists have found that the satellite's emissions contain chemical elements that may indicate the formation of organic substances under the surface.

Plumes of Enceladus. Photo: NASA/JPL-Caltech/Space Science Institute

The last mission of the probe was called Grand Finale, it consisted of a controlled fall of the device into the planet’s atmosphere. During this time, Cassini flew between the surface of Saturn and its rings 22 times (the distance is approximately 2 thousand kilometers).

One of the last images from Cassini, taken on September 13, 2017. Photo: NASA/JPL-Caltech/Space Science Institute
The last photo of the device. Photo: NASA/JPL-Caltech/Space Science Institute

“This is the final chapter of an amazing mission, but it is also the beginning. "Cassini's discovery of ocean worlds on Titan and Enceladus changed everything, upending our understanding of amazing places to look for potential life beyond Earth," said Thomas Zurbuchen, associate administrator for NASA's Science Office.

Cassini mission control center after receiving the last signal from the probe. Screenshot from NASA Jet Propulsion Laboratory broadcast

The Cassini spacecraft, which was sent to Saturn in 1997, uses very little fuel. However, NASA plans to destroy it to avoid an accidental collision with one of Saturn's moons and its contamination, since this could affect alien life, if it exists, of course. But before Cassini is destroyed, it will continue to fly between Saturn and its rings and record as much new data as possible.

How long is the mission to explore Saturn?

Researchers have been working to design, build, launch and operate a mission to study Saturn for the past three decades.

The nuclear-powered Cassini spacecraft was launched in October 1997, but did not enter orbit around the gas giant until July 2004 and has since been collecting data about the planet itself and its moons. But all good things come to an end sooner or later. And for NASA's $3.26 billion space probe, that day will be September 15, 2017.

What caused the need to destroy the device?

During a press conference held at the US space agency on April 4, the researchers explained why they want to destroy their spacecraft and how they plan to carry out a plan called the Grand Finale. To destroy Cassini, NASA researchers will use the remaining fuel reserves on it and send it on a collision course with Saturn.

"It was Cassini's discoveries that led scientists to decide to destroy it," said Earl Maze, an engineer at NASA's Jet Propulsion Laboratory who is leading the mission.

Maze was referring to the ocean of warm salt water that was discovered by the apparatus. This ocean hides under the icy crust of Enceladus, a large moon of Saturn, and its vapors are sent into space. A NASA probe flew through this plume of steam and ice in October 2015, analyzed the material and indirectly studied the composition of the subsurface ocean. It turned out that it is capable of supporting extraterrestrial life.

"We can't allow the craft to inadvertently collide with this pristine object," Maze said. - Cassini must remain at a safe distance. And since we would like to send it to Saturn, the only choice is to destroy the probe ourselves, controlling this process.” But Maze and researchers from 19 countries aren't going to let their probe go down without a fight. They plan to get the last bytes of data the robot can collect before Cassini meets its end on Saturn.

The purpose of the spacecraft

Long before Cassini entered Saturn's orbit in 2004, mission scientists were analyzing its trajectory so that the vehicle could move freely and safely past the giant gas planet, its moons and icy rings. Their goal is to obtain as many new images, gravity data, and magnetism readings as possible without putting the ship in danger or using too much of its limited rocket fuel.

Fuel shortage

But after 13 years of operation at a distance of almost 1.45 billion kilometers from Earth, Cassini's fuel tank was almost empty. This means that the mission is nearing completion, but once the fuel runs out, scientists' ability to control the vehicle will be very limited. This was stated by Jim Green, head of NASA's planetary science program, during a press conference.

NASA may send Cassini to some other planet, perhaps Uranus or Neptune. In 2010, however, mission managers decided to keep it in orbit around Saturn because they thought it would make the mission more scientifically efficient. But this effectively dooms the spaceship to a fiery death.

How scientists plan to destroy the device

The mission will officially begin on April 22, 2017. It is then that the device will fly for the last time near Titan - the icy satellite of Saturn, which has a denser atmosphere than our planet, seas of liquid methane, and even rain.

Titan's gravity will act like a slingshot for Cassini. The device will fly over Saturn (its atmosphere) and on April 26 will pass through the narrow space between the planet and the inner edge of its rings.

This maneuver will be the “farewell kiss” of the device, since scientists do not intend to return it back to the planet’s orbit.

Latest data

The space between Saturn and its rings is just under 2 thousand kilometers wide. "Once it gets this close to the planet, it will give scientists a better view of its poles than ever before," said Linda Spilker, Cassini project scientist and NASA planetary scientist. It will be possible to see giant hurricanes at the north and south poles of Saturn.

During its final flight over Saturn, Cassini will be able to get very close to the planet's north pole, which remains poorly understood. This pole has a hexagonal shape, and perhaps by approaching it, scientists will be able to understand what contributes to its clear parameters.

Cassini will also take photos of the glow at Saturn's poles, determine what material the planet's massive rings are made of, and even study what's hiding beneath its clouds.

Sensitive magnetic and gravitational measurements, which Cassini could not previously make from the planet's orbit, will help answer questions about Saturn's internal structure, including how large its rocky core is and how quickly the shell of metallic hydrogen spins around it.

“How fast does Saturn rotate? - asks Spilker. “If the inclination to the magnetic field is small, this will help us calculate the length of its day.” A few hours before its final dive on September 15, 2017, the device will send the last batch of images to Earth and then be ready for destruction.

Farewell to Cassini

Cassini is a 2.78-ton robot equipped with delicate instruments that are not designed to plow through the icy material of Saturn's rings at speeds greater than 112,000 kilometers per hour. Moreover, it was not designed to plunge into the atmosphere of a gas giant and continue to work, sending data to scientists.

Still, the scientists leading the mission say they are going to do everything possible to protect the instruments from damage and preserve data until the final moments of the craft's operation. First of all, they are going to do this with the main cone-shaped antenna, using it as a shield for the camera and other important parts of the device. But even if the device loses contact with the Earth, it will still fall where scientists planned. The only difference is that they will not be able to obtain new data, as they are currently planning.

Grand finale

As Cassini begins its final drive, it will use its last propellant to fight atmospheric drag and keep its antenna pointed at Earth. During this time, it will study the atmosphere of Saturn, broadcasting readings of the composition of gases in real time to Earth. But the measurements will not last long at all. The device will begin to disintegrate, evaporate, and eventually become part of the planet for which it left Earth 20 years ago to explore. While Cassini crew members say they are looking forward to the Grand Finale, they still can't help but feel a sense of regret.

"It's really going to be hard to say goodbye to this little spacecraft that was able to do so much for science," Spilker said. "We've been together for a long time."

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In development of the device Many scientists from NASA and ESA took part. It was created in order to study Saturn and its moons in more detail.

Cassini is the most complex, largest and expensive of the American automatic interplanetary spacecraft (project budget more than $3 billion). Its weight was 6 tons, and its height was more than 10 meters. On board it was installed 12 scientific instruments and a retractable rod for a magnetometer. Communication with the Earth is provided by a 4 meter Italian antenna. The device does not have solar panels, because at such a great distance from the Sun they are ineffective. Cassini's energy is provided by 3 radioisotope thermoelectric generators containing a total of almost 33 kilograms of radioactive plutonium. More than half of Cassini's launch weight was fuel. Attached to Cassini is the Huygens probe, intended to land on Titan. It is also designed to photograph the surface of Titan.

Cassini flight

Cassini launched on October 15, 1997. An American Titan 4B rocket was used to launch it into space. But an interesting fact is that when the device was launched into space, it was not directed towards Saturn at all, but rather towards Venus. The thing is that it was decided to use gravity maneuvers, i.e. take advantage of the gravitational field of the planets. Thus, in 1998 and 1999, Cassini orbited Venus, in August 1999 it passed near the Earth at a speed of 69,000 km/h, and in the winter of 2000 it flew past Jupiter, transmitting its photographs to Earth. In January 2004, specialists began to activate the Cassini equipment. Even when approaching Saturn, the device flew 2068 km from one of its satellites, Phoebe.

The photographs of this strange satellite transmitted to Earth turned out to be sensational. An irregularly shaped asteroid dotted with craters appeared before the eyes of scientists. When examining the craters, layers of some kind of white substance were discovered on some of them. They assumed it was ice.

In order to finally be in Saturn's orbit, Cassini performed a braking maneuver. This maneuver was a very important and significant calculation, which was placed in advance in the device’s computer. The day of July 1, 2004 has arrived. At 2:11 GMT, Cassini passed the ascending node of the trajectory and overcame the plane of Saturn's rings. After 24 minutes, one of the two braking engines turned on. It worked for 97 minutes, during which time Cassini passed the lowest point above the clouds of Saturn (20,000 km to the clouds). In addition to Phoebe, 8 more satellites were planned for research: Mimas, Dione, Hyperion, Tethys, Rhea, Enceladus and Titan, which became the main object of study among the satellites of Saturn.

Of course, over the 4 years of the mission, Saturn itself will also be studied, because it still holds many mysteries. The rings of Saturn are also being carefully studied. Scientists want to know their composition, gravitational and electromagnetic effects. Great attention will be paid to the planet's atmosphere. This planet has the lowest density among the planets of the solar system. In general, the study project is designed for 4 years, but Cassini’s energy will last for another 200 years, so perhaps it will be able to return to Titan and other satellites more than once. Scientists had an idea to then send the device towards the Kuiper belt, but most likely they will not do this, because... and Saturn and its satellites still keep many secrets.

The first artificial satellite of Saturn, the Cassini probe, has completed its mission. It burned up in the planet's atmosphere. The probe transmitted images to Earth that will allow scientists to learn more about Saturn, its rings and satellites. The brightest of them are in the RBC photo gallery.

The Cassini interplanetary probe was created by NASA, the European Space Agency and the Italian Space Agency. It launched from Earth in October 1997 and was intended to study Saturn, its rings and moons.

(Photo: NASA/JPL/University of Colorado)

The probe reached Saturn in 2004. The Cassini orbital station is part of the complex. ​It consisted of an orbital station and a descent module with the Huygens automatic station, intended for landing on Titan, which took place on January 14, 2005.

(Photo: NASA/JPL/Space Science Institute)

The final part of the Saturn exploration began in April 2017. The probe was supposed to fly between Saturn and its rings, which no human-made device had ever done before. After 22 such flybys, as expected, Cassini ran out of fuel (it was powered by three radioisotope thermoelectric generators using plutonium-238), and it was sent into the dense layers of the planet's atmosphere, where it burned up.

(Photo: NASA/JPL/Space Science Institute)

Signals from Cassini on Earth were received within 83 minutes after the death of the spacecraft. Scientists hope that before his death he managed to convey information that will give a more complete understanding of the structure of Saturn’s atmosphere.

(Photo: NASA/JPL/Space Science Institute)

In total, 17 countries are involved in the research program. More than 250 scientists around the world are involved in processing the data coming from Cassini.

(Photo: ESA/NASA/JPL/University of Arizona)

Cassini began flying around the rings of Saturn from the North Pole, and as it moved, the flight altitude decreased from 72.4 thousand km above cloud level.

“No spacecraft has ever been this close to Saturn. We could only rely on predictions based on our knowledge of Saturn's other rings, our ideas about what the gap between the rings and Saturn was like. “I’m pleased to report that Cassini made it through this gap as we planned and returned in excellent shape,” Cassini mission director Dr. Earl Maze in April 2017.

(Photo: NASA/JPL/Space Science Institute)

The mission was originally scheduled to close in 2008. However, it was subsequently extended.

The Cassini probe became the first artificial satellite of Saturn, and the Huygens probe became the first spacecraft to make a soft landing in the outer region of the Solar System (starting outside the orbit of Mars and the asteroid belt).

(Photo: NASA/JPL-Caltech/Space Science Institute)

In 2004, when the probe reached Saturn, it was winter in the northern hemisphere and it was in the shadow.

(Photo: NASA/JPL-Caltech/Space Science Institute)

The total cost of the mission was more than $3.26 billion.