In 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 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.
Cassini is a spacecraft, an automatic interplanetary station exploring Saturn, its rings and planetary system. Named after astronomer Giovanni Cassini, it was launched towards the giant planet in October 1997. Since then, the probe has been working diligently, taking pictures, measuring the spectrum, the magnetosphere, mapping the surface of Saturn, Titan and its other satellites, and in 2017 it will die when faced with the subject of its studies. Together with Cassini, the 320-kilogram Huygens probe went to Saturn. The Cassini-Huygens mission itself was extremely successful and allowed us to see Saturn and its system from a variety of angles.
Earth and Titan, Saturn's largest moon, have one remarkable similarity - they are the only space objects in the solar system where there are liquid lakes and seas. While on our planet they are filled with fresh or salt water, on Titan they consist of methane and ethane with a temperature of about minus 170-180 degrees Celsius. Recently, two groups of scientists studied data from the "" apparatus and discovered an interesting feature of Titan - it has not only small lakes that quickly dry up, but also deep reservoirs formed thousands of years ago.
For the past 13 years, the 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. On Friday, at 7:55 Eastern Time, the Earth will stop receiving data from Cassini, as the device will fall into the atmosphere of Saturn at the speed of a meteor and will be purposefully destroyed. Astronomers have been preparing for this moment for many years.
The Cassini-Huygens mission is a significant 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 find out the secrets of the “ringed” planet
About this sensational space mission, Doctor of Physical and Mathematical Sciences L. Ksanfomality wrote the following: “The achievements of modern technology are amazing. The Cassini-Huygens spacecraft, launched in 1997, safely 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 rustling 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 interplanetary station Pioneer 11 and continued by the famous Voyagers. As a result, scientists received a lot of valuable information about Saturn, its rings and satellites, but they were never able to see the surface of this mysterious planet. A proposal arose to start a new project to fill the gaps in knowledge about Saturn and its family.
The Cassini-Huygens mission was the embodiment of this project, involving NASA, ESA (European Space Agency) and the Italian Space Agency (ASI). The main financial costs ($2.6 billion) were borne 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 the long-distance antenna communications and radar altimeter (RADAR). It is worth noting that in general, scientists and engineers from 17 countries took part in the creation of Cassini and Huygens.
Cassini Station was named after the 17th-century French scientist Giovanni Cassini, who in 1675 discovered that Saturn's ring was made up of many concentric rings. The Huygens probe was named after the 17th-century Dutch scientist Christian Huygens, who was the first to see Titan in 1655, and in 1656 he discovered the rings of Saturn.
New satellites, massive 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 Titan-4 B launch vehicle and an additional Centaur booster unit. Initially, Cassini aimed at Venus; for its acceleration, the device used the gravitational fields of three planets for two years. Before arriving at Saturn, all its systems were in the so-called sleep mode; only in the winter of 2000 did Cassini become active and began to delight scientists with unique data from the depths of the Solar system.
On December 30, 2000, the device performed a maneuver in the gravitational field of Jupiter, then it approached the giant planet at a minimum distance. Cassini took many color images of Jupiter and carried out a number of scientific measurements. Before its closest approach to Saturn on June 11, 2004, Cassini passed by its satellite, Phoebus, 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 consists mainly of ice and is closer in structure to comets than to asteroids. Scientists enthusiastically greeted these first results of the mission, but even more sensational data awaited them.
The most important stage of the mission was the entry of the vehicle into the orbit of Saturn, carried out on July 1, 2004 using a special braking maneuver. Cassini even managed to pass between two rings (F and G), although without avoiding several collisions. Fortunately, the device did not lose its functionality and successfully approached Saturn as close as possible and became its satellite. Over the next four years, he made 74 revolutions, exploring the surface of Saturn and its moons.
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 Metona, Pallene and Polydeuces. On May 1, 2005, a satellite named Daphnis was discovered in the Keeler gap. Like the moon Pan, its orbit lay within the rings. Cassini also discovered the moons Anfa, Aegeon and S/2009 S 1.
During the mission, a detailed survey of the surface of Saturn and its many moons was carried out: Mimas, Rhea, Phoebus, Titan, Tethys, Dione and Hyperion, as well as Epimetheus. With the help of Cassini, scientists were able to examine in detail the ring system of Saturn and learn a lot about the nature of its satellites. The images, taken on September 5, 2005, show “spokes” in the rings, first discovered by astronomers back in 1977. Later, in the 1980s, their presence was confirmed by 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 depths of Enceladus made it possible to search for life on the small moons of the giant planets. Cassini also helped solve the mystery of the two-faced nature of Iapetus, which worried scientists for a long time. It turned out that the whole point was the dark dust that covered the front of the moon during Iapetus’ orbital trajectory. The dark area absorbed energy and warmed up, while the uncontaminated area remained cool. Due to the long period of rotation of Iapetus, a corresponding visual effect of the two-faced satellite arose.
On April 15, 2008, NASA announced an extension of the mission until July 2010. The new phase of the mission included 60 additional flybys around Saturn, 26 approaches to Titan, 7 to Enzlad and one each to 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 stage of the mission includes 155 additional orbits around Saturn, 54 approaches to Titan and 11 to Enceladus, which scientists are very interested in.
And it's raining again on Titan...
Well, now it’s time to remember about Huygens, because it’s not for nothing that Cassini “carried” this probe 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 imagine how its landing would go, so the management of the Huygens project said that the main task of the device was to study the atmosphere of the satellite, but as for its “attachment”, it depends on your luck.
However, everything went extremely well; three opened parachutes slowed down the speed of the descent of the device, which lasted 2 hours 28 minutes to 4.5 m/s at the moment it touched the surface of Titan. During the descent, atmospheric parameters were measured and the surface of Saturn's satellite was photographed. 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 became the first Earth 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. For 3 hours and 44 minutes, Huygens transmitted information to Earth. The probe took nearly 350 photographs of Titan and its atmosphere, recorded the sounds of raging winds at the landing site, and even drilled into the soil with a small probe. As expected, the temperature on the surface of Titan turned out to be minus 179 degrees Celsius; because of this, the probe, of course, could not work for long, but it brilliantly completed its task. The image 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 in diameter, filled with liquid hydrocarbons. On March 13, 2007, the mission leadership made a sensational statement about the discovery of real seas in the northern hemisphere of Titan, one of which is even larger in size than our Caspian Sea. Many scientists say that Titan's landscape resembles that of Earth - mountains, lakes, seas... Data obtained by Cassini and Huygens suggest that inside Titan there is a rock or iron core, and its mantle consists of a layer of ice several hundred thick kilometers.
Radar data, of course, does not allow us to establish what hydrocarbons fill the lakes and seas on Titan; scientists suggest that they could be methane and ethane, and they also admit some amount of 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 through them.
Interestingly, apart from Titan and the Solar System, not a single satellite has an atmosphere. Why does Titan have it?
Titan was thought to be promising for discovering life; According to scientists, its dense atmosphere could create a greenhouse effect and a temperature at the surface quite acceptable for living organisms. Add to this the presence of methane and other organic components, and you will understand the increased interest in this satellite on the part of those who are busy searching for life in the Universe.
As on Earth, the main component of Titan's atmosphere is molecular nitrogen (about 85%), the remaining 15% is represented by argon, methane and smaller components. For scientists, the threefold excess, compared to Earth, of the nitrogen-15 isotope in Titan’s atmosphere relative to nitrogen-14 remains a mystery.
There is no doubt that the Cassini-Huygens mission was a complete success. Scientists' assumption was confirmed that Titan is similar to the Earth as it was before life began 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 trip in a time machine.
During its mission, the device made 293 revolutions around Saturn, among which it made 162 passes near its moons and discovered 7 new ones, transmitted 453,048 photographs to Earth as part of 635 GB of scientific data and became the source of 3,948 scientific publications. He discovered an ocean on Enceladus, as well as an ocean, 3 seas and hundreds of small lakes on Titan. About 5 thousand people from 27 countries participated in this project, and its total cost was $3.9 billion, in which the initial shares were distributed as: $2.6 billion from the American agency NASA, $500 million from the European ESA and $160 million from Italian ASI.
Cassini design
The Cassini-Huygens apparatus is undergoing testing. The round orange part in the foreground is Huygens landing on Titan, the white part is the 4-meter Cassini antenna/radar
Diagram of the device from different angles:
The probe, named after Giovanno Cassini (who discovered Saturn's moons 2 to 5), is a whopping 6.8 m tall and 4 m wide with a dry weight of 2150 kg (it was the third heaviest interplanetary probe after a pair of Soviet "Phobosov") Saturn reaches only 1.1% of the solar energy available to us in Earth's orbit, so the probe is powered by 3 RTGs of the same huge size as the device itself - they have 32.7 kg of plutonium-238 (this is 3.6 times more than it was both Voyagers at launch have 6.8 times more than Curiosity has and apparently more plutonium available to NASA at the moment:,). The device has 1,630 individual electronic components and 22 thousand wire connections with a total cable length of 14 km, and is controlled by duplicated 16-bit 1750A computers (another of these was controlled by the Titan IV launch vehicle that launched the device into orbit). The scientific equipment includes 12 instruments grouped into three groups, which are intended for 27 separate scientific studies:
Optical range sensors:
1) Composite infrared spectrometer, including cameras of 3 ranges (CIRS); 2) wide-angle and narrow-angle (33 cm in diameter) visible range cameras with a set of several filters for different colors and CCD matrices with a resolution of 1024x1024 pixels. (ISS); 3) ultraviolet spectrometer, including 4 telescopes (UVIS); 4) a mapping spectrometer of the visible and infrared range, dividing the light visible to it into 352 spectral sections (VIMS);
Sensors of magnetic fields and charged particles:
Radio wave sensors:
11) a 4-meter-diameter radar designed for mapping the satellites of Saturn (Radar); 12) scientific radio subsystem, which consists of using the main 4-meter antenna to observe Saturn, its rings and satellites through radio waves (RSS). Saturn's signal delay is 68-84 minutes one way.
Through thorns to Saturn
The weight of the orbital and landing probes was too great for them to be directly launched to Saturn (with Huygens’ 350 kg, the total weight of the device was 2.5 tons) - even taking into account the fact that the Titan IV on which Cassini-Huygens flew had a 40% greater payload load than the Titan IIIE on which the Voyagers flew. Therefore, the devices had to wander a lot around the Solar System, picking up speed with gravitational maneuvers to meet Saturn: after the launch on October 15, 1997, a 5.7-ton bunch of two devices filled with 2978 kg of fuel set off to meet Venus. Having performed 2 gravity assist maneuvers on April 26, 1998 and June 24, 1999 (in which they flew only 234 and 600 km from the planet, respectively), they returned briefly to Earth on August 18, 1999 (flying 1171 km from us) after which We've already set off for Jupiter.
A photograph of the Moon taken by the narrow-angle camera of the device in near ultraviolet, from a distance of about 377 thousand km and a shutter speed of 80 μs.
Flying through the asteroid belt, the device met on January 23 with the Mazursky asteroid: unfortunately, the distance was 1.6 million km, and the asteroid itself was only 15x20 km in size, so the photo was less than 10 by 10 pixels. On December 30, 2000, Cassini-Huygens met with Jupiter and its brother Galileo, whose mission was already approaching its finale (he completed his mission almost 14 years ago with the same selfless feat that Cassini is now going to perform). This 4th gravity assist maneuver finally gave the two vehicles enough speed to rendezvous with Saturn on July 1, 2004, by which time it had already traveled 3.4 billion km.
In order not to waste time, the mission team used the device’s radio antennas to clarify the Shapiro effect (slowing down the propagation of a radio signal as it moves in the gravitational field of a heavy object). The measurement accuracy was increased from previous results of 1/1000 for the Vikings and Voyagers to 1/51000. The results, published on October 10, 2003, were in complete agreement with the predictions of general relativity.
The graph clearly shows peaks of encounters with planets (after which the spacecraft increases speed), a long descent with a slight break near Jupiter (when the device flew towards Saturn, gradually exchanging kinetic energy for potential energy, getting out of the “gravitational well” of the Sun), and a series waves at the end (when the device entered the orbit of Saturn and began to rotate in its orbit).
The long-awaited meeting and the main mission
On May 27, 2004, Cassini turned on its main engine for the first time since December 1998 to give the apparatus an impulse of 34.7 m/s, which was needed to correct the trajectory, which took it on June 11 2068 km from Phoebe, a very distant satellite of Saturn, which supposedly formed in the Kuiper Belt and was subsequently captured by the gravitational pull of Saturn. Due to the huge orbital radius of this satellite (averaging about 12.5 million km), this was Cassini's only encounter with this satellite.On July 1, the main engine of the device was turned on again (for 96 minutes) to reduce the speed to 626 m/s to enter Saturn orbit. On the same day, Methone was discovered and Pallene was rediscovered, which was discovered in another one of the Voyager 2 images, but since it was not in the other images, the orbit of the celestial body could not be established and for 25 years it received the designation S/1981 S 14. The very next day, Cassini made its first flyby of Titan, on October 24 another satellite (Polydeuces) was discovered, and on December 24 the Huygens landing probe was dropped.
On January 14, 2005, Cassini acted as a relay for the landing probe (discussed below), and the next day the device came as close as possible to Titan and, using its radar, discovered a 440-kilometer crater on its surface. On May 6, the satellite Daphnis was discovered, which lives on the edge of the Keeler gap:
At the edges of the 42-kilometer gap, waves were discovered caused by the very weak attraction of Daphnis (whose weight is only 77 billion tons, which creates an attraction 25-100 thousand times lower than that of Earth):
Saturn's equator and the plane of its rings are tilted 27° relative to the ecliptic, so we can observe both poles of Saturn as well as observe its rings from the upper and lower sides. But since they are observed at a large angle and from enormous distances (1.2-1.66 billion km depending on the relative position of the Earth and Saturn), it was simply impossible to see anything there, so let’s say the hexagon of Saturn was only discovered Voyagers flying past.
A natural color photograph of Saturn, consisting of 36 Cassini images taken on January 19, 2007, using three filters (red, green and blue). The exposure of the images was taken with the expectation of visibility of the dark areas of the rings, so the surface of Saturn turned out to be greatly overexposed.
In 2005, it was found that about 250 kg of water vapor leaves it every second through the geysers of Enceladus at a speed of up to 600 m/s. In 2006, scientists were able to establish that they are the source of material for the penultimate and widest ring - the E ring.
On July 22, 2006, the device flew over the northern latitudes of Titan and on the radar map made by the device, dark areas were first discovered, indicating that in these places there are methane lakes on the surface. During the 127 flights of this satellite, many areas of its surface were studied in detail, some of which showed dynamic changes. Among these was the Ligeia Sea, which has dimensions of 420x350 km and an average depth of about 50 m with a maximum of more than 200 m (maximum depth recorded by radar):
The most likely causes of such measurements are considered to be waves, solids below or above the surface, or bubbles in the liquid (which affect the reflectivity of the surface).
On May 30, 2007, the 2-kilometer Anfa satellite was discovered, and on September 10, the device passed only 1,600 km from Iapetus, but already while transmitting the images, a particle of cosmic rays hit the device’s computer, which caused it to go into safe mode. Fortunately, no pictures were lost. Shortly before this event, Arthur C. Clarke’s video congratulations on this event arrived (according to one of his famous novels - “2001: A Space Odyssey” - there was one of the monoliths on the surface of Iapetus).
Video greeting and its translation
Hello! This is Arthur Clarke joining you from my home in Colombo, Sri Lanka.
I'm glad to be part of this event with the Cassini spacecraft flyby of Iapetus.
I send my greetings to all friends - known and unknown - who have gathered on this important occasion.
I'm sorry I can't be with you as I'm wheelchair bound with polio and don't plan to leave Sri Lanka again.
Thanks to the World Wide Web, I have been able to follow the progress of the Cassini-Huygens mission since its launch several years ago. As you know, I have more than just an interest in Saturn.
And I was really scared in early 2005 when the Huygens probe transmitted sound recordings from the surface of Titan. This is exactly what I described in my 1975 novel Earth Empire, where my character listens to the winds blowing across the desert plains.
Perhaps it was a foretaste of things to come! On September 10, if all goes according to plan, Cassini will take our closest look at Iapetus, one of Saturn's most interesting moons.
Half of Iapetus is as dark as asphalt, while the other half is as light as snow. When Giovanni Cassini discovered Iapetus in 1671, he could only see the bright side. We took our best sneak peek when Voyager 2 flew past it in August 1981 - but that was almost a million kilometers away.
On the other hand, Cassini is going to pass just over a thousand kilometers from Iapetus.
This is a particularly exciting moment for fans of 2001: A Space Odyssey, because the Saturn monolith discovered by lone astronaut David Bowman has become a gateway to the stars.
The 35th chapter of the novel, entitled “The Eye of Iapetus”, contains the following fragment:
Discovery approached Iapetus so slowly that the movement was almost not felt and it was impossible to notice the moment when an elusive change occurred and the cosmic body suddenly became a landscape some eighty kilometers below the ship. The reliable verniers gave their final corrective pushes and fell silent forever. The ship entered its last orbit: the turnaround time was three hours, the speed was only one thousand three hundred kilometers per hour. Greater speed was not required in this weak gravitational field. Discovery became a satellite of Sputnik.More than 40 years later, I can't remember why I placed the Saturn monolith on Iapetus. At the beginning of the Space Age, ground-based telescopes could not discern the details of this celestial body. But I've always had a strange fascination with Saturn and its family of moons. By the way, this “family” was growing at a very impressive pace: when Cassini was launched, we only knew about 18 of them. I understand that there are now 60 of them, and their number continues to increase. I can't resist the temptation to say:
My God, there are a lot of satellites there!
However, in the film, Stanley Kubrick decided to place all the action in the Jupiter system rather than Saturn. Why this change? Well, on the one hand, it made the plot more straightforward. More importantly, the special effects department was unable to produce a model of Saturn that Stanley found convincing.
This was done correctly, because otherwise the film would have become obsolete with the flyby of the Voyager mission, which presented the rings of Saturn in a way that no one could even imagine.
I've seen plenty of examples of Neptune being depicted in art, so I'll keep my fingers crossed when Cassini flies past Iapetus.
I want to thank everyone associated with the mission and the entire project. It may lack the glamor of manned spaceflight, but the science project is extremely important to our understanding of the solar system. And who knows - perhaps one day our survival on Earth will depend on what we discover there.
This is Arthur Clarke, I wish you a successful flight.
Map of Iapetus with a resolution of 400 m per pixel (original 5 MB):
Approximately 40% of the surface of this satellite is occupied by dark areas with an albedo 10 times less than the light areas. Now the source of such a big difference is considered to be the effect of separation of dust and ice, when ice evaporates from dark areas and deposits on light areas, thereby making light areas even lighter and dark areas becoming darker. The reason that the remaining satellites behave “normally” is that they have a shorter day length, during which the surface does not have time to warm up sufficiently.
Extension and Cassini Equinox mission
On July 1, 2008, Cassini's extended 27-month mission began, which included 21 additional flybys of Titan, 8 Tethys, 7 Enceladus, 6 Mimas, and one flyby each of Dione, Rhea, and Helena.On August 15, 2008, Aegeon was discovered, which, although it was named after a monster with 100 arms and 50 heads, was an almost harmless “pebble” 500 m in diameter (it was so small that its dimensions had to be determined by brightness, so that the exact we do not know the shape of this satellite). And on October 9, Cassini performed its most dangerous maneuver - a flyby just 25 km from Enceladus (and this at a speed of 17.7 km/s!). The mission team took such a risky step in order to directly analyze the composition of the water vapor of its geysers.
During its 23 flybys of Enceladus during the entire mission (in 10 of which the device approached at a distance of less than 100 km), it was found that the subsurface ocean was 11-12 units (which is unsuitable for terrestrial life forms), but in Nitrogen (4±1%), carbon dioxide (3.2±0.6%), methane (1.6±0.6%) as well as traces of ammonia, acetylene, hydrocyanic acid and propane (which speaks of the active formation of organic substances under the surface of Enceladus). Unfortunately, the device does not contain special instruments for recording complex organics (since they could not even imagine that the device would find such during mission planning), so the answer to the question “is it possible for life to exist under the surface of Enceladus?” Cassini left it for his followers.
By July 26, 2009, the last of the satellites discovered by Cassini was discovered - the 300-meter S/2009 S 1, which was discovered thanks to the 36-kilometer shadow it casts on the far edge of the B ring along which its orbit lies:
Second extension and Cassini Solstice mission
In February 2010, a decision was made to further extend the mission, which began in September and was supposed to last until May 2017, when the final fate of the device was to be decided. It included another 54 flybys of Titan and 11 flybys of Enceladus.The efforts of Cassini and his team, who managed to secure an additional allocation of about $400 million for the next 7 years of the mission (bringing the cost of the program to almost $4 billion), were not in vain: already in December 2010, during the flyby of Enceladus, the device established the presence of an ocean under the north pole (later it was found that the ocean is not limited only to the polar region). In the same year, the Great White Spot appeared again on the surface of Saturn - a huge storm that appears in the atmosphere of Saturn approximately every 30 years (Cassini was very lucky with this, and it managed to register such storms twice - in 2006 and 2010). On October 25, 2012, the device recorded a powerful discharge inside it, which raised the temperature of the stratospheric layers of the atmosphere by 83°C above normal. Thus, this vortex became the hottest storm in the solar system, even surpassing Jupiter's Great Red Spot.
"The Day the Earth Smiled"- a project organized on July 19, 2013 by the head of the Cassini imaging team, during which Cassini took a picture of the entire Saturn system, which also included the Earth, Moon, Venus and Mars. A total of 323 photographs were taken, of which 141 were further used to compile the mosaic:
The ground is in the lower right corner, and the original without signatures is (4.77 MB).
In parallel with this, NASA launched a campaign "Wave to Saturn" during which 1,600 photographs were collected, from which a mosaic was assembled on November 12, which appeared on the cover of the New York Times on the same day (beware, the original weighs 25.6 MB):
From 2012 to 2016, the device recorded changes in the color of Saturn’s hexagon (photos from 2013 and 2017, original 6 MB):
"Huygens"
The landing probe, named after Christiaan Huygens (discoverer of Titan in 1655, on which the probe landed), is a 318-kilogram apparatus with a diameter of 2.7 meters with 6 sets of instruments:
1) a constant frequency transmitter designed to measure wind speed using the Doppler effect (Doppler Wind Experiment - DWE);
2) sensors for the physical properties of the atmosphere that measure the density, pressure and electrical resistance of the atmosphere, as well as acceleration sensors on all three axes, which, together with the previous device, allow you to set the density of the atmosphere (Huygens Atmospheric Structure Instrument - HASI);
3) cameras of the visible and infrared spectra, in parallel with obtaining images, measuring the spectrum and illumination at the current altitude of the device (Descent Imager / Spectral Radiometer - DISR);
4) a pyrolyzer of aerosol particles that heats samples taken from two different heights and redirects them to the next device (Aerosol Collector and Pyrolyser - ACP);
5) a gas chromatography-mass spectrometer measuring the composition and concentration of individual components of Titan’s atmosphere, and at the last stage, also the top layer of soil evaporated by the heater (Gas Chromatograph Mass Spectrometer - GCMS);
6) a set of instruments for measuring surface properties, which includes an acoustic sensor that measures the density/temperature of the atmosphere in the last 100 m of descent based on the properties of sound reflected by the surface (Surface-Science Package - SSP).
Huygens separated from Cassini on December 24, 2004, and reached Titan's atmosphere by January 14. The descent in the atmosphere took 2 hours and 27 minutes, during which the thermal protection of the device and its three parachutes were sequentially activated, and after landing it transmitted data from the surface for another 72 minutes (until the Cassini probe, which acted as a signal relay, went beyond the horizon).
International cooperation of the Huygens probe
"Grand Finale"
In May 2017, the future fate of the device was being decided: by the end of the second extended mission, it had very little fuel left, and 19 possible options for completing the mission were considered, including a collision with Saturn, its main rings or icy satellites, removal from Saturn’s orbit to a heliocentric one orbit or stable orbit around Titan/Phoebe (and even the option of a collision with Mercury). As a result, it was decided to send the device into the atmosphere of Saturn in order to thus protect the satellites of Saturn from their possible biological contamination. To accomplish this task, the device performed a maneuver near Titan on April 22, which redirected it into the 2000-kilometer gap between Saturn and its nearest ring.Since then, it has made 21 orbits at a distance of only 1600-4000 km from the Saturian clouds, all the while approaching Saturn's atmosphere, and is currently on its last 22nd orbit. The device will take its last pictures before entering the atmosphere, after which it will deploy its 4-meter antenna towards the Earth, and will transmit data on the composition of the Saturian atmosphere from its spectrometers until it can fend off atmospheric disturbances. Soon after losing contact with it, it will collapse and burn up in the dense layers of Saturn’s atmosphere - somewhere there, in the constellation Ophiuchus, 1.4 billion km from us.
Thanks to the space station, we got the opportunity to see Saturn and its moons almost live
Moscow. September 15th. website - On Friday at 14:54 Moscow time, the almost 20-year mission of the Cassini space probe ended. After several final flights, the interplanetary station was sent into the atmosphere of Saturn, in the dense layers of which it burned up.
The probe transmitted data about the atmosphere of the second largest planet in the solar system until its end. The collected information is enough for many years of research: the device transmitted 453,048 photographs to Earth during its life, which is 635 GB of scientific data. All new images taken by Cassini are presented on a special page on the NASA website. The total cost of the project was $3.9 billion.
The Cassini station, which has shown enviable longevity and endurance, has a solid track record: 293 orbits around Saturn, of which 162 passes near its satellites, 7 discovered new satellites of the planet: Methone, Polydeuces, Pallene, Daphnis, Antha, Aegeon and S/2009 S 1 The probe discovered an ocean on Saturn's sixth-largest moon, Enceladus, as well as an ocean, three seas and hundreds of small lakes on Titan.
The probe was named after the Italian astronomer and engineer Giovanni Cassini. Its mission began on October 15, 1997 with the launch of a TitanIVB/Centaur rocket. It carried NASA's Cassini probe and the European Space Agency's Huygens probe, which was attached to it and was designed to study Titan, Saturn's largest moon.
In 2004, Cassini flew to the gas giant and separated from Huygens - he headed towards Titan. Huygens' mission lasted until January 14, 2005 and ended an hour after landing on Titan, however, during this relatively short time he made many discoveries.
Cassini's mission included studying the structure of the rings, as well as the dynamics of the atmosphere and magnetosphere of Saturn.
On October 9, 2008, Cassini was forced to do its most dangerous maneuver - flying at a speed of 17.7 km/s 25 km from Enceladus. This was necessary in order to analyze the composition of the water vapor of its geysers.
During the entire mission, the probe made 23 flybys of Enceladus. In ten of them, the device approached at a distance of less than 100 km. He found that the subsurface ocean of the satellite is unsuitable for terrestrial life forms, but in the secretions of geysers he discovered chemical elements that may indicate the formation of organic substances under the surface of the satellite.
The probe's mission was extended several times - first after the completion of the main mission in 2008, and again in 2010. However, the device’s life has nevertheless come to an end; its fuel reserves have almost run out. On April 4, 2017, the mission was announced to end on September 15, 2017.
Scientists have calculated that if the spacecraft falls on Enceladus, terrestrial bacteria may end up on the satellite. Therefore, the decision was made to send Cassini to Saturn.
The final mission of the probe was called Grand Finale. It consists of a controlled fall into the planet's atmosphere after several final flybys. During this time, the station followed a spiral trajectory and made 22 “dives” in the 2000-kilometer space between the surface of the planet and its rings.
The probe took its last pictures several hours before entering the atmosphere. When approaching the planet, the station’s antenna turned toward the Earth transmitted data collected by spectrometers about Saturn’s atmosphere. As a result of the final mission, scientists will receive a large amount of information about the planet itself and its ring system.