The Cassini-Huygens mission is a milestone in the history of space exploration, during which the Cassini orbital station became the first artificial satellite of Saturn, and the Huygens lander made the first soft landing in the Outer Solar System on the surface of Titan.
To learn the secrets of the "ringed" planet
About this sensational space mission, Doctor of Physical and Mathematical Sciences L. Xanfomality wrote the following: “The achievements of modern technology are amazing. The Cassini-Huygens spacecraft, launched in 1997, successfully covered 4 billion kilometers and arrived at the destination of its journey. Along the way, he took color photographs of the surface of Saturn, its most distant satellite, Phoebe, and the rings of the giant planet. And when the Huygens research apparatus, separated from Cassini, landed on the surface of Titan, the largest moon in the solar system, people on Earth heard the wind in the atmosphere of a distant planet, saw mountains, plains and rivers on its surface ... "
The first studies of the distant mysterious Saturn were started by the American Pioneer 11 interplanetary station and continued by the famous Voyagers. As a result, scientists have received a lot of valuable information about Saturn, its rings and satellites, but they have not been able to see the surface of this mysterious planet. There was a proposal to start a new project, filling in the gaps in knowledge about Saturn and his family.
The Cassini-Huygens mission was the epitome of this project, involving NASA, ESA (European Space Agency) and the Italian Space Agency (ASI). The main financial costs ($ 2.6 billion) were undertaken by the Americans, ESA allocated 500 million, and the Italian Space Agency - 160. NASA scientists created the Cassini station, the European Space Agency - the Huygens probe, and Italian engineers designed a long-range antenna communications and radar altimeter (RADAR). It is worth noting that, in general, scientists and engineers from 17 states took part in the creation of Cassini and Huygens.
Cassini Station was named after the 17th-century French scientist Giovanni Cassini, who in 1675 established that Saturn's ring was made up of many concentric rings. The Huygens probe was named after the 17th-century Dutch scientist Christian Huygens, he was the first to see Titan in 1655, and in 1656 he discovered the ring of Saturn.
New satellites, large-scale storms and other discoveries
On October 15, 1997, Cassini was launched with Huygens attached to the station. The device was launched into space using a special launch vehicle "Titan-4 B" and an additional block for overclocking "Centaur". Initially, Cassini aimed at Venus, using the gravitational fields of three planets for two years to accelerate the device. Before arriving at Saturn, all of its systems were in the so-called sleep mode, only in the winter of 2000, Cassini became more active and began to delight scientists with unique data from the depths of the solar system.
On December 30, 2000, the device made a maneuver in the gravitational field of Jupiter, then it approached the giant planet at a minimum distance. Cassini took many color photographs of Jupiter and made a number of scientific measurements. Before the closest approach to Saturn on June 11, 2004, Cassini passed by its satellite, Phoebe, and unique images of the cosmic body were transmitted to Earth. It turned out that this satellite, about 200 km in size, has an irregular shape and is very similar to an asteroid. It was possible to establish that the satellite mainly consists of ice and is closer in its structure to comets than to asteroids. Scientists enthusiastically greeted these first results of the mission, but even more sensational data awaited them ahead.
The most important stage of the mission was the entry of the device into the orbit of Saturn, carried out on July 1, 2004 using a special deceleration maneuver. "Cassini" even managed to pass between the two rings (F and G), however, without avoiding several collisions. Fortunately, the device did not lose its working capacity, successfully approached Saturn as close as possible and became its satellite. In the next four years, he made 74 revolutions, exploring the surface of Saturn and its satellites.
In 2004, while studying images from Cassini, scientists discovered three new moons of Saturn. Of course, they were small in size, at the beginning of 2005 they were given the names of Meton, Pallene and Polydeuces. On May 1, 2005, a satellite named Daphnis was discovered in the Keeler Gap. Like Pan's satellite, its orbit lay inside the rings. Cassini also discovered the moons Anfa, Egeon, and S/2009 S 1.
During the mission, a detailed survey of the surface of Saturn and its many satellites was carried out: Mimas, Rhea, Phoebe, Titan, Tethys, Dione and Hyperion, as well as Epimetheus. With the help of Cassini, scientists were able to examine in detail the system of Saturn's rings and learn a lot about the nature of its moons. The images taken on September 5, 2005 show "spokes" in rings, first discovered by astronomers back in 1977. Later, in the 1980s, their presence was confirmed by the Voyagers. Until now, scientists are puzzling over the mechanism of formation of these "spokes".
With the help of Cassini, it was possible to discover a hot plume on Enceladus and the presence of water ice on this satellite. The discovery of signs of the existence of a water ocean in the bowels of Enceladus made it possible to search for life on the small moons of the giant planets. Cassini also helped unravel the mystery of the two-facedness of Iapetus, which worried scientists for a long time. It turned out that it was all about the dark dust that covered the front of the moon on the orbital trajectory of Iapetus. The dark area absorbed energy and warmed up, while the unpolluted area remained cool. Due to the long period of rotation of Iapetus, a corresponding visual effect of the satellite's two-facedness arose.
On April 15, 2008, NASA announced an extension of the mission until July 2010. The new leg of the mission included 60 additional flybys around Saturn, 26 close encounters with Titan, 7 with Enzlad and one each with Dione, Rhea and Helena. Cassini was supposed to continue studying Saturn, its rings and magnetosphere. On February 3, 2010, another mission extension was announced until September 2017. The second new phase of the mission includes 155 additional orbits around Saturn, 54 encounters with Titan and 11 with Enceladus, which is of great interest to scientists.
And it's raining again on Titan...
Well, now it's time to remember the Huygens, because it was not in vain that Cassini “dragged” this probe on itself for such a long time. In mid-December 2004, Huygens successfully separated from the orbiter and began its independent journey. On January 14, 2005, he began his descent to the surface of Titan. Of course, it was difficult to guess how its landing would go, so the Huygens project management said that the main task of the apparatus was to study the satellite’s atmosphere, but as for its “titanization”, it’s all about luck.
However, everything went extremely well, three opened parachutes slowed down the speed of the descent of the apparatus, which lasted 2 hours 28 minutes, to 4.5 m / s at the moment of touching the surface of Titan. During the descent, atmospheric parameters were measured and the surface of Saturn's moon was surveyed. At an altitude of 25 km, the surface was almost invisible, hidden by methane fog. At an altitude of 19 km, the fog disappeared, but rather dense clouds appeared. But below 18 km, visibility became quite decent.
It is worth recalling that Huygens was the first terrestrial probe to land on a satellite of one of the planets, not counting the Moon, as well as the first apparatus to land on the surface of a celestial body on the periphery of the solar system. 3 hours 44 minutes "Huygens" transmitted information to Earth. The probe took almost 350 pictures of Titan and its atmosphere, recorded the sounds of the raging wind at the landing site, and even drilled the ground with a small probe. As expected, the temperature on the surface of Titan was minus 179 degrees Celsius, because of this, the probe, of course, could not work for a long time, but it brilliantly completed its task. The picture of the surface of Titan, transmitted by Huygens, is somewhat similar to the rocky desert of Mars.
On Titan, there were lakes ranging in size from one to tens of kilometers across, filled with liquid hydrocarbons. On March 13, 2007, the mission leadership made a sensational announcement about the discovery of real seas in the northern hemisphere of Titan, one of which even exceeds our Caspian Sea in size. Many scientists say that the landscape of Titan resembles the earth's - mountains, lakes, seas ... The data obtained by Cassini and Huygens suggest that there is a stone or iron core inside Titan, and its mantle consists of a layer of ice several hundred kilometers.
Radar data, of course, does not allow us to determine what hydrocarbons fill the lakes and seas on Titan, scientists suggest that they may be methane and ethane, they also admit some liquid nitrogen. A number of photographs show branched channels flowing into local lakes and seas; it is possible that rivers or temporary streams could flow along them.
Interestingly, apart from Titan and the solar system, not a single satellite has an atmosphere. Why does Titan have it?
Titan was supposed to be promising for discovering life; according to scientists, its dense atmosphere could create a greenhouse effect and a temperature at the surface that is quite acceptable for living organisms. Add to this the presence of methane and other organic components, and the increased interest in this satellite from those who are engaged in the search for life in the Universe becomes clear.
As on Earth, the main component of Titan's atmosphere is molecular nitrogen (about 85%), the remaining 15% are argon, methane and smaller components. For scientists, the three-fold excess, compared with the Earth, of the content of the nitrogen-15 isotope in the atmosphere of Titan in relation to nitrogen-14 remains a mystery.
Undoubtedly, the Cassini-Huygens mission was a complete success. Scientists have confirmed the assumption that Titan is similar to the Earth, as it was before the birth of life on it, 4 billion years ago. Thus, by studying Titan, scientists will be able to look into the distant past of our planet, one might say, make a kind of journey in a time machine.
1446
In just a few hours, the Cassini spacecraft, which has orbited Saturn since 2004, will photograph our planet. Of course, the Earth is not the only and not even the main goal of today's study, but I think it would be interesting for many to look at the small blue dot from a distance of 1.44 billion kilometers. Interestingly, almost simultaneously with Cassini, on July 19 and 20, the Earth will be photographed by the MESSENGER spacecraft orbiting Mercury.
Some might even want to tonight/night (shooting starts at 21:27 GMT) to go outside and wave to Cassini. In the meantime, we can recall the best photos of this mission, which has been going on for over 15 years.
Before Saturn, Cassini visited Jupiter and took a number of pictures of the largest planet in the solar system. In the presented photo, one of the most famous satellites of the gas giant Io, famous for its volcanic activity.
Two Titans. The largest satellite of Saturn against the background of the planet.
The tiger stripes of Enceladus, one of the most geologically active and unusual bodies in the solar system.
A huge shadow from the planet falls on the rings of Saturn.
A flash of sunlight reflected off a methane lake on Titan.
Saturn's moon Prometheus photographed from a distance of approximately 34,000 kilometers. Prometheus is also called the "shepherd" of the F ring. The gravitational field of Prometheus creates kinks and loops in the rings, and the satellite, as it were, "steals" material from them.
Prometheus creates a disturbance in the F ring.
Equinox on Saturn.
Ice eruption on Endelalad. It is believed that the material ejected from the satellite is the source that feeds the outer ring of Saturn, known as the "F Ring"
Saturn's moon Mimas. The huge Herschel Crater, left over from an ancient cataclysmic collision that almost split the satellite in half, makes it somewhat similar to the Death Star.
Saturn's moon Hyperion. The unusual appearance is due to the consequences of several catastrophic collisions at an early stage in the formation of the solar system. The density of Hyperion is so low that it probably consists of 60% ordinary water ice with a small admixture of stones and metals, and voids make up the bulk of its internal volume.
Shadow from the rings of Saturn on the surface of the planet.
Storm on Saturn.
Mimas against the background of the rings of Saturn.
The shadow of Titan on the surface of Saturn.
Four satellites of Saturn and its rings in one image.
Titanium. Before the Cassini-Huygens mission, we didn't know much about what was happening on its cloudy surface.
Saturn and its rings.
→In the development of the device many scientists from NASA and ESA took part. It was created in order to study Saturn and its satellites in more detail.
Cassini is the most complex, largest and most expensive of the American automatic interplanetary spacecraft (the project budget is over $3 billion). Its weight was 6 tons, and its height was more than 10 meters. On board were 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 is powered by 3 radioisotope thermoelectric generators containing a total of almost 33 kilograms of radioactive plutonium. More than half of Cassini's starting weight was occupied by fuel. Attached to Cassini is the Huygens probe, designed to land on Titan. It is also designed to photograph the surface of Titan.
Flight of Cassini
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 apparatus was launched into space, it was directed not at all towards Saturn, but rather towards Venus. The thing is that it was decided to use gravitational maneuvers, i.e. take advantage of the gravitational field of the planets. Thus, in 1998 and 1999, Cassini turned around Venus, in August 1999 passed near the Earth at a speed of 69,000 km / h, in the winter of 2000 flew past Jupiter, transmitting his 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.
Pictures of this strange satellite transmitted to Earth turned out to be sensational. Before the eyes of scientists appeared an asteroid of irregular shape, dotted with craters. When examining the craters, layers of some kind of white matter were found on some of them. They assumed it was ice.
In order to finally be in orbit around Saturn, Cassini performed a deceleration maneuver. This maneuver was a very important and significant calculation, which was previously placed in the computer of the device. 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 brake motors turned on. He 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 research 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 carefully studied. Scientists want to know their composition, gravitational and electromagnetic effects. Great attention will be paid to the atmosphere of the planet. 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 be enough for another 200 years, so it is possible that he will be able to return to Titan and other satellites more than once. The scientists had an idea, then send the device towards the Kuiper belt, but most likely they will not do this, because. and Saturn and its satellites still keep a lot of secrets.
On September 15, 2017, at about 2:55 pm Moscow time, Cassini completed its long-term mission, the spacecraft that has compiled the most detailed picture of Saturn to date. Now, thanks to Cassini, we know about new moon-worlds where life could have arisen, about the structure of huge and amazing rings, as well as about the colossal storms that exist on the gas giant. The device has collected a huge amount of data on the only satellite in the solar system with its own atmosphere - Titan. In memory of one of the most complex, expensive and successful interplanetary missions, we propose to recall its main results.
Twenty years ago
The development of the Cassini-Huygens mission began in 1982 by a joint working group of the US National Academy of Sciences and the European Science Foundation. 19 countries and three space agencies (NASA, ESA and the Italian Space Agency) participated in the creation of the device. By that time, three vehicles had already visited the ringed planet - Pioneer 11 (1979), Voyager 1 (1980) and Voyager 2 (1981). One of the major discoveries of previous missions was that Saturn's largest moon, Titan, has an extremely dense atmosphere that makes it impossible to directly explore its surface. In addition, it became clear that the poles of the planet's magnetic field coincide surprisingly exactly with the geographic ones - this unusual find greatly complicated a seemingly simple task: to find out the length of the day on Saturn.
The new joint mission was supposed to tell more about the features of the Saturn system. Initially, it was supposed to last about three years, and the main attention of scientists was paid to the atmosphere of Titan and Saturn, the magnetosphere of the gas giant, the geology of its satellites and the analysis of the composition of the ring system.
On October 15, 1997, the spacecraft took off from Cape Canaveral. The journey to Saturn lasted more than six years - Cassini made gravitational maneuvers near Venus (twice), Earth and Jupiter, and only in the summer of 2004 reached the goal. Subsequent discoveries were the reason to extend the mission three times: first for two years in connection with the Saturnian equinox, then for another six years during the change of seasons, and, in the end, for the “Grand Finale” (Grand Finale) - the final four-month stage .
landing on titan
One of the most impressive results of the mission was the landing of the Huygens lander on Titan on January 14, 2005. This is a unique satellite with a dense atmosphere (one and a half times denser than the earth), the only such object in the entire solar system. When developing the probe, the researchers took into account a number of theories that Titan could be covered in a methane ocean, Huygens was ready for both splashdown and landing on solid ground. As it turned out later, there really are liquid reservoirs on Titan - ammonia-methane seas, but they occupy a relatively small part of the satellite.
Huygens not only studied the composition of the atmosphere (near the surface, the proportion of methane reaches five percent, otherwise it consists of nitrogen), but also measured the speed of winds near the surface of the satellite - it turned out to be about several meters per second, which is comparable to weak terrestrial winds. The probe also transmitted images from the surface of Titan and even recorded sounds surrounding him during the descent. Subsequent joint analysis of data from Huygens and Cassini suggested that there is a huge water ocean under the surface of the satellite.
Scientists also showed that Titan has its own analogue of the water cycle in nature, only methane plays the role of water in it. Just as water rains on Earth, methane rains periodically occur on Titan, and the relief and shape of the rocks on the surface of the satellite indicate the existence of liquid flows.
Huygens' activity on Titan is the only successful landing in the outer solar system to date.
Clouds over Saturn from afar look like cosmic brush strokes - this is the effect of the interaction of liquid components in the planet's atmosphere
Geysers of Enceladus
In 2005, photographs and other data collected by Cassini revealed that at least one of Saturn's moons is geologically active. Previously, it was believed that this was impossible, since the satellites had cooled down and were located too far from the Sun, however, over the south pole of Enceladus, the apparatus "saw" clear traces of geysers - 250-kilometer plumes of water gushing from under the surface. Their sources turned out to be long faults on the icy surface of the satellite - the so-called "tiger stripes".
In subsequent years, a significant part of the mission's efforts was devoted to the study of these plumes. First, the researchers proved that their source is not an isolated reservoir, like a subglacial lake, but a global ocean that covers the entire satellite. Its depth is estimated at 45 kilometers, the thickness of the ice above it ranges from two to twenty kilometers.
Almost two years ago, the device made a dangerous maneuver, flying through water plumes at an altitude of only 49 kilometers above the surface of the satellite. His mass spectrometers recorded a large amount of hydrogen in the emissions, as well as methane and carbon dioxide. Their concentrations, as well as the very fact of their presence, indicate that hydrothermal processes are taking place at the bottom of the ocean, which may well provide energy to living organisms. Today, Enceladus is considered one of the most promising places in the solar system for the origin of extraterrestrial life.
Saturn at Solstice
The birth of the rings
The rings are perhaps the most recognizable feature of Saturn. This is a system of dust rings stretching for hundreds of thousands of kilometers, the thickness of which in some places is only tens of meters. So far, neither the age of the rings nor their exact origin is known. Astronomers consider this system as a prototype of the young solar system, in which the planets were just beginning to form.
Cassini showed the extraordinary complexity and variability of this system. Thus, the numerous moons of Saturn cause various turbulences in the rings with their gravity, as happens in the F-ring under the influence of Pandora and Prometheus. Some of the rings are still forming, such as the E-ring, which is ejected from the geysers of Enceladus.
Thanks to Cassini, a new object was discovered in this system - the Janus-Epimetheus ring, formed from dust and rock particles thrown out in collisions of Janus and Epimetheus with various celestial bodies. Also, images from the device made it possible to detect amazing structures on the border of the B-ring - a kind of "mountains" rising 2.5 kilometers above the plane of the rings.
In addition, the device discovered at least eight new moons of Saturn by studying the rings. Among them are Polydeuces, Pallene, Methone, Anthas, Aegeon and Daphnis. The diameter of these celestial bodies does not exceed several kilometers.
Seasons of Saturn
One of the main advantages of Cassini is the long duration of the mission. For 13 years of being near Saturn, the device saw several changes in the planet's seasons - from winter to summer in the northern hemisphere (the Saturnian year lasts almost 30 Earth years). Even though the giant is ten times farther from the Sun than Earth, changes in light exposure still lead to significant changes in the gas giant's atmosphere. For example, the giant hexagon, a regular hexagonal storm that rages at the north pole, changed its color from blue to gold during the mission. Scientists attribute this to chemical transformations occurring in the atmosphere under the influence of an increasing amount of sunlight in connection with the onset of summer.
The north pole of Saturn in the rays of the sun. Giant hexagon above the pole - storm
Seasons are associated with another phenomenon on the gas giant - the formation of "spokes" in the rings of Saturn. These are oblong wedge-shaped objects that rotate with the rings, but are located at some height above them. Spokes were discovered by the Voyagers, but thanks to Cassini, it became clear that this, apparently, is a periodic phenomenon that occurs at the end of the Saturnian winter.
A year after the Saturnian equinox, with the advent of spring in the northern hemisphere of the giant, the researchers found a huge storm in the Cassini images. Its area is eight times the surface area of the Earth. According to the readings of the instruments, up to ten lightning flashes per second flashed in the storm. Its driving force also turned out to be changing lighting.
A magnetic field
One of the tasks facing Cassini turned out to be too tough for him. According to the daily changes in the magnetic field of Saturn, the apparatus had to find out what the true length of the day on the planet is. Usually such fluctuations are observed when the magnetic field is slightly deviated from the axis of rotation of the planet. But in the case of Saturn, the deviation between the magnetic field and the poles turned out to be less than 0.06 degrees.
Direct attempts to measure the rotation speed from magnetic field fluctuations gave a rather large spread - from 10.6 to 10.8 hours, depending on the season of measurements and the hemisphere over which the apparatus was located. A number of additional measurements are planned for the "Big End" of the mission.
And, of course, not to mention hundreds of thousands of pictures made by Cassini (we have already published some of them earlier - and), and gigabytes of scientific data transferred, still awaiting processing. In the last act of the mission, the device made a number of dangerous measurements that were previously inaccessible. In close (only a few thousand kilometers above the clouds) approaches of the past four months, the probe studied in detail the gravitational and magnetic fields of Saturn, collected information about the material that makes up the inner rings. Until the loss of the signal, Cassini continued to transmit in real time information from the mass spectrometer, which makes it possible to determine what substances surround the device. It will take a long time to analyze them, and it is quite possible that its results will bring new discoveries - for example, the riddle of the age of Saturn's rings will finally be solved. We can only wait for new publications from the mission team and hope for a speedy continuation of research in the system of a ringed planet.
Vladimir Korolev
View of Saturn's C and B rings from the inside
For the past 13 years, the Cassini spacecraft has been silently changing our understanding of the solar system. The Cassini mission, a $3.62 billion joint project between NASA and the European Space Agency, was to study the gas giant Saturn and its many moons. But tomorrow this mission will come to its literally burning end. At 7:55 pm ET on Friday, the Earth will stop receiving data from Cassini, as the device will fall at the speed of a meteor into Saturn's atmosphere and will be purposefully destroyed. Astronomers have been preparing for this moment for many years.
All of the spacecraft's instruments are still working fine, but the long mission has used up nearly all of the propellant needed to correct the probe's orbital path around Saturn. But instead of just letting the craft get out of hand and possibly crash somewhere else, the mission control team programmed the probe's computer to re-enter Saturn's atmosphere in order to save the planet's moons and any likely life forms on them.
Despite all the merits of this spacecraft, Cassini, so to speak, has always been an outsider. Its mission was not as spectacular as the New Horizons mission that flew past Pluto, or any other Mars-related mission, where the US agency has sent more than one lander and rover over the past couple of decades. Saturn-related topics rarely made headlines. However, the lack of hype in no way diminished the degree of scientific importance of the discoveries that Cassini made.
If we discard the formalities, then it began on October 15, 1997, when Cassini was launched into Earth orbit aboard the Titan IVB / Centaur launch vehicle. The launch was joint - the launch vehicle also put into orbit the Huygens probe, built by the European Space Agency. This vehicle was designed to land on Saturn's largest moon Titan, from where it could transmit scientific data to researchers on Earth.
The launch was not without incident. There were people who protested against the launch of Cassini for fear of contamination of the environment by plutonium fuel, on the basis of which the spacecraft is powered. Before the launch of Cassini, physicist Michio Kaku said that if the launch fails and the rocket explodes, radioactive material will rain down on people near the launch complex. NASA and government agencies were quick to assure everyone that such a situation is simply impossible. Fortunately, in the end, the launch did indeed pass without any problems.
Two spacecraft arrived at Saturn 7 years after they were launched from the launch complex at Cape Canaveral. Huygens landed on Titan on January 14, 2005. Since then, Cassini has made many orbits around the planet and its moons. Thanks to him, we got the opportunity to take a fresh look at this system, to understand the features of the rings of the planet.
satellites
From the giant Titan to the tiny moon Daphnis, Cassini's observations have revealed a lot about the moons of this giant ring planet. Saturn and its moons can literally be viewed as a miniature solar system.
Epimetheus
Elena
Hyperion
Mimas, a moon similar to the Death Star
Pandora
Titan and Tethys (foreground)
Daphnis creating waves inside Saturn's rings
Pan (similar to a dumpling)
Top 5 Cassini discoveries
It is difficult to enumerate all the contribution to planetary science that Cassini has made over the 13 years of its mission, but it is not at all difficult to understand how much this mission means to scientists on Earth. Below are just a few of the most important discoveries made by this probe in more than a decade of its operation.
Geysers on Enceladus
Cassini not only spotted, but flew through the ejecta of liquid water shot into space from the subsurface ocean of Enceladus. The discovery was amazing. The moon's ocean may well have the right chemistry for life, making it one of the most desirable targets for finding extraterrestrial life inside the solar system.
Titan's "Earth-Like" Environment
By watching Titan, we were able to learn more about ourselves. Exploration of one of Saturn's largest moons has revealed to us the complex world of lakes of liquid methane and dunes of hydrocarbons. To the untrained observer, Titan may appear similar to Earth, but it is clearly an alien planet, providing a perfect example of the diversity among planetary bodies.
Many moons of Saturn
Until the launch of Cassini to Saturn in 1997, scientists only knew about the existence of 18 moons orbiting the ring giant. While the spacecraft has been moving towards this planet for seven years, the researchers have discovered 13 more satellites. However, today, thanks to Cassini, we were able to find out that Saturn is the "father" of as many as 53 moons.
Saturn Hexagonal Storm
Cassini has captured some truly impressive images of Saturn over the course of its history, but perhaps the most impressive yet unique are the photographs of the planet's poles. We were able to see in detail the hexagonal flow of atmospheric currents surrounding a powerful storm raging at the north pole of Saturn. According to NASA, the area of this hurricane is 50 times larger than the area of the average hurricane on Earth.
Empty space between the rings of Saturn
Before the climax of the mission, Cassini took a position between the planet's rings and Saturn itself. And as it turned out, it is incredibly calm here. Instead of the expected dust swirls tossing between the planet and the rings, Cassini has found absolutely empty space as part of its latest orbital flybys.
A mission to be missed
Although, as noted above, the Cassini mission was not as bright as the Martian ones, it proved to be very useful for modern astronomy. Each month, the probe sent truly unique, never-before-seen images and new scientific data back to Earth. Many aspiring astronomers have built their careers around this data.
Completion of the mission will be a real loss for the scientific and pseudo-scientific community. Especially given the fact that, apart from the probe that will study Jupiter's moon Europa, NASA and other space agencies have no plans, at least in the visible future, to continue studying the horizons of the distant worlds of the solar system like Saturn, Neptune and Uranus.
