Memories of the Cassini probe: all about the mission to Saturn

22 last turns - and the end. On April 26, 2017, the Cassini interplanetary probe made the first of a series of flights through a 2400-kilometer gap between the sparkling rings of Saturn at a speed of 125 thousand km / h, hiding from small fragments by the antenna. On September 15, he will deploy an antenna to Earth and go on his last leap into the abyss of the atmosphere of the gas giant. Another minute - and that’s it: now, until several weeks remain until this moment, scientists do not hope that the signals from the device will come longer. But it will be new data about one of the most amazing worlds of the solar system. Flying between the planet and its rings, the device will measure their gravity and determine the mass of ice in the rings. This will help determine their age and resolve the issue of origin. Billions of years ago, together with the planet itself? Or, on the contrary, relatively recently, from other celestial bodies, as Cassini showed for ring E, filled with emissions of Enceladus? Suddenly the probe will even consider a suspicious object in ring C, which may be the nucleus, the rest of the body, broken by rings? With each turn, approaching the atmosphere of Saturn, Cassini will turn his attention to it, take a picture of the storms and follow the composition - perhaps discovering the riddles of some strange steady storms. Scientists expect that after another two minutes of silence the probe will finally evaporate, but we will have answers and memories.

Saturn

Gas giant with a system of ice rings and numerous satellites. 95 times heavier than the Earth and 9.5 times further from the Sun, the local year lasts 29.4 of our years. It consists mainly of hydrogen, the average density is less than water (0.69 g / cm3). Very stormy atmosphere (winds at the equator can blow faster than 500 km / h) and a powerful magnetic field that creates auroras. Cassini made 294 orbits around the planet.

Rings

Flat and thin, from particles of ice and dust ranging in size from micrometers to meters. The densest are rings A and B, separated by a Cassini gap. The inner ring D reaches the atmosphere, the outer rarefied ring of Phoebe stretches millions of kilometers from it. Passing through the rings and their slots, Cassini turned the antenna plate forward, using it as a shield against possible collision with random particles.


Hex Storm

At the north pole of Saturn, clouds form an unusual hexagonal storm with a diameter of about 25 thousand km. As shown by Cassini, it goes into the atmosphere for almost 100 km. The nature of these stable formations remains unclear. Perhaps they appear as a result of the interaction of several rapidly rotating vortices with slower flows of the atmosphere itself.

Spiral anomalies

The attraction of satellites causes disturbances in the rings of Saturn. Cassini discovered that some of them are directed toward the planet, as if something was breeding on it itself. It is hard to imagine that the gas giant had mountains or other sources of gravitational anomalies, and the phenomenon has not yet been explained. Perhaps this is how the vibrations of the solid core of Saturn manifest themselves.

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Cassini specified the speed of rotation of Saturn around its axis: 10 hours 45 minutes 45 seconds. This is about six minutes slower than the Voyager probes recorded in 1980 and 1981.

Don Garnett (University of Iowa): “I don’t think that anyone decided in this connection that the whole planet could slow down. It seems that there is a certain lag between the rotation of the bowels of the planet and its magnetic field. "


Yellow fog

Through the dense atmosphere of Titan, the Huygens probe descended for almost two and a half hours, noting that the wind speed reaches 26 km / h, and at a height of 18-19 km thick clouds hang. From above, he removed a complex “river” relief, and rounded pebble stones were found at the landing site. For about an hour and a half, the probe worked on the surface, having managed to transfer to Cassini about 350 photographs in yellow shades of methane fog.

Saturn's moons

Saturn's moon

62 satellites

13 sizes> 50 km

Beyond the rings and between them

Scientific missions

635 GB of data

453, 048 shots

162 flights near satellites

3948 scientific publications

Spacecraft cassini

Weight: 2150 kg; Dimensions: 4x6.7 m; Power system: 885/603 W at the end of work; Total cost: $ 3.26 billion; Participants: US space agencies (NASA), the European Union (ESA), Italy (ASI) and 14 other countries.

1.4-meter high-directional radar antenna for mapping Titanium and other satellites, a pair of wide-directional antennas.

2. A space plasma particle spectrometer (CAPS).

3. An analyzer of cosmic dust (CDA), which allows you to find out the size, speed, charge and direction of motion of particles.

4. IR spectrometer (CIRS) for remote temperature measurements.

5. INMS mass spectrometer analyzing the composition of charged and neutral volatile particles.

6. Cameras with wide-angle and telephoto lenses.

7. Tools for charged particle analysis, mapping and study of the magnetosphere (MIMI-LEMMS).

8. MAG magnetometer on a retractable 11-meter mast.

9. Antennas and sensors of the RPWS instrument for recording the plasma and radio wave environment of the apparatus.

10. Huygens Launch Module (DM) complete with Landing Module (EAM), which provided a soft landing on Titan's surface on January 14, 2005.

11. Sources of energy: three RTGs (32.7 kg of plutonium-238).

12. Spectrometers for visible and infrared radiation (VIMS).

13. UV spectrometer (UVIS).

14. The main and backup R-4D engines on a self-igniting mixture of nitrogen tetraoxide and monomethylhydrazine (thrust 445 N). There are also 16 weak shunting hydrazine engines with a thrust of 1 N each.


Enceladus

The most brilliant body of the solar system: a bright reflection (0.9 of the incident visible radiation) gives a light, cracked ice surface. In the spring of 2008, Cassini passed just 50 km above it, through emissions of ice geysers at the satellite’s south pole, particles of which form the E ring. Everything indicates that it has a heavy core and a liquid ocean of water, at least in the southern hemisphere.

Exact measurements of the gravitational field of Enceladus confirmed that under its ice surface lies a liquid ocean with a depth of about 10 km.

David Stevenson (California Institute of Technology): "Given our knowledge of what celestial bodies are made of, like this, the most natural option would be water."

New satellites of Meton and Pallen, 3 and 4 km across, were discovered. They are between the orbits of Mimas and Enceladus, about 200 thousand km from the center of Saturn.


Titanium

Disproportionately large satellite, which accounts for more than 96% of the mass of all the moons of Saturn. The only body of the solar system, except for the Earth, on which the liquid constantly exists and its circulation takes place. The only satellite with a dense atmosphere. Clouds and precipitation, lakes and rivers of methane, active crust of heavy hydrocarbons, cryovolcanism - Cassini made 127 rapprochements with Titan.

Carolyn Porco (Space Research Institute, Colorado): “One of the main tasks of returning to Saturn was to inspect the system to search for new bodies. It’s nice to think that among the fantastic discoveries coming to us in the coming years, we can already note the confirmation of two new moons. ”

On Titan, hydrocarbon reservoirs — rivers, lakes, and entire seas filled with liquid methane and other light hydrocarbons — were found and mapped well.

Larry Soderblom (US Geological Survey): “We saw that these areas are darker than anything on Titan ... Cassini showed that these are lakes, quite like those on Earth. Titan as a musical crescendo: each passage is more interesting than the previous one. ”


Rhea

The bowels of the tiny Rhea, apparently, are not differentiated, and it is a mixture of rock and ice. The satellite moves with the same side forward, and the leading hemisphere is rich in impact craters, and the back is traces of tectonic activity caused by deformation of the satellite by the gravity of Saturn. Cassini noted the deceleration of electrons in the vicinity of Rhea, which may indicate the presence of a weak ring system.

Chronology

Flight

1997

Launch aboard the HP Titan IV, launched from the launch site at Cape Canaveral

1998−2000

- Maneuvers in the gravitational field of Venus, Earth and Jupiter

- Flight near the asteroid (2685) Masurian

Main mission

2004

- Arrival in the system of Saturn

- Flights near the satellites of Phoebe and Titan

- Discovery of new satellites: Metona, Pallena, Polydeus

- Huygens probe compartment (mass: 319 kg; diameter: 2.7m)

2005−2007

- Soft landing of Huygens on the surface of Titan (January 14, 2005)

- Observation of Saturn and its rings, flights near major satellites

- Possible detection of a weak ring system in Rhea

- The maximum rapprochement with Titan - 960 km

- Discovery of satellites Daphnis and Anfa

Main mission

Equinox Mission

2008

- The last flight in the framework of the main mission of Cassini near Titan

- Discovery of the Egeon satellite

- New Equinox Mission Announced for Observing Saturn at the Local Equinox

- Plans for the next Solstice science mission announced

Equinox Mission

2009−2010

- A few more flights near Titan and Enceladus

- Short standby due to technical issues. After rebooting, the probe almost completely restored

Last jump

Mission Solstice

2010−2017

- Work on the Cassini Solstice program until the spring of 2017: another 155 revolutions around Saturn, 54 flights around Titan, 11 - around Enceladus, 2 - around Rhea and 3 - Dions

- 123 608 km / h - maximum speed

- 4 passes through ring D

- 5 flights through the upper atmosphere

- 1 minute from entering the atmosphere to losing contact

- The fall into the atmosphere of Saturn and the death of Cassini

The article “Answers and Memories” was published in the journal Popular Mechanics (No. 10, October 2017). I wonder how a nuclear reactor works and can robots build a house?

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