This sequence of "proximal orbits" will end when another encounter with Titan sends the probe into Saturn's atmosphere. Cassini—Huygens' s origins date to , when the European Science Foundation and the American National Academy of Sciences formed a working group to investigate future cooperative missions. Two European scientists suggested a paired Saturn Orbiter and Titan Probe as a possible joint mission.
At the time, NASA was becoming more sensitive to the strain that had developed between the American and European space programs as a result of European perceptions that NASA had not treated it like an equal during previous collaborations. NASA officials and advisers involved in promoting and planning Cassini—Huygens attempted to correct this trend by stressing their desire to evenly share any scientific and technology benefits resulting from the mission.
In part, this newfound spirit of cooperation with Europe was driven by a sense of competition with the Soviet Union, which had begun to cooperate more closely with Europe as ESA drew further away from NASA. The collaboration not only improved relations between the two space programs but also helped Cassini—Huygens survive congressional budget cuts in the United States.
Congress that it would be unwise to halt the project after ESA had already poured funds into development because frustration on broken space exploration promises might spill over into other areas of foreign relations. The project proceeded politically smoothly after , although citizens' groups concerned about its potential environmental impact attempted to derail it through protests and lawsuits until and past its launch. The spacecraft was planned to be the second three-axis stabilized, RTG -powered Mariner Mark II , a class of spacecraft developed for missions beyond the orbit of Mars.
As a result, Cassini became more specialized. The Mariner Mark II series was cancelled. Including the orbiter and probe, it is the second-largest unmanned interplanetary spacecraft built, [16] [17] as well as being among the most complex.
Only the two Phobos 1 and 2 spacecraft sent to Mars by the Soviet Union were larger. The Cassini spacecraft is 6. Spacecraft complexity is increased by its trajectory flight path to Saturn, and by the ambitious science at its destination. Cassini is powered by Huygens was supported by Cassini during cruise, but used chemical batteries when independent. At present the Cassini probe is orbiting Saturn, at a distance of 8. It takes 68 to 84 minutes for radio signals to travel from Earth to the spacecraft, and vice versa.
Thus ground controllers cannot give "real-time" instructions for daily operations or for unexpected events. Even if response was immediate, at least two hours pass between the occurrence of a problem and the reception of the engineers' response by the satellite.
Titan 's surface revealed by VIMS. Rhea in front of Saturn. Saturn's north polar hexagon [19]. Instruments: [20]. Telemetry from the communications antenna and other special transmitters an S-band transmitter and a dual-frequency K a -band system will also be used to make observations of the atmospheres of Titan and Saturn and to measure the gravity fields of the planet and its satellites.
VIMS spectra taken while looking through Titan's atmosphere towards the Sun helps understand the atmospheres of exoplanets artist's concept; May 27, A Cassini RTG before installation. Because of Saturn's distance from the Sun, solar arrays were not feasible as power sources for this space probe. To gain momentum while already in flight, the trajectory of the Cassini mission included several gravitational slingshot maneuvers: two fly-by passes of Venus , one more of the Earth, and then one of the planet Jupiter.
The terrestrial flyby was the final instance when the Cassini space probe posed any conceivable danger to human beings. The Cassini spacecraft is capable of transmitting in several different telemetry formats. The telemetry subsystem is perhaps the most important subsystem, because without it there could be no data return. The telemetry was developed from ground up, due to the spacecraft using a more modern set of computers than previous missions.
There are currently around channels in 67 mini-packets assembled in the Cassini Telemetry Dictionary. Out of these 67 lower complexity mini-packets, 6 mini-packets contained the subsystem covariance and Kalman gain elements measurements , not used during normal mission operations.
This left measurements in 61 mini-packets. A total of seven telemetry maps corresponding to 7 AACS telemetry modes were constructed.
These 7 maps cover all spacecraft telemetry modes. Template:Doubleimage The Huygens probe, supplied by the European Space Agency ESA and named after the 17th century Dutch astronomer who first discovered Titan, Christiaan Huygens , scrutinized the clouds, atmosphere, and surface of Saturn's moon Titan in its descent on January 15, It was designed to enter and brake in Titan's atmosphere and parachute a fully instrumented robotic laboratory down to the surface.
The probe system consisted of the probe itself which descended to Titan, and the probe support equipment PSE which remained attached to the orbiting spacecraft. The PSE includes electronics that track the probe, recover the data gathered during its descent, and process and deliver the data to the orbiter that transmits it to Earth.
Huygens communications would have been entirely lost if not for testing in flight that discovered a Doppler-related problem, requiring a change in orbital trajectories to compensate. Picture of the Moon during flyby. The Cassini space probe performed two gravitational-assist flybys of Venus on April 26, , and June 24, These flybys provided the space probe with enough momentum to travel all the way out to the asteroid belt.
At that point, the Sun's gravity pulled the space probe back into the inner Solar System. One hour and 20 minutes before closest approach, Cassini made its closest approach to the Earth's Moon at , kilometers, and it took a series of calibration photos. It took photos [37] in the period five to seven hours before the flyby at a distance of 1. Cassini made its closest approach to Jupiter on December 30, , and made many scientific measurements. About 26, images of Jupiter, its faint rings , and its moons were taken during the six month flyby.
Cassini photographed Io transiting Jupiter on January 1, A major finding of the flyby, announced on March 6, , was of Jupiter's atmospheric circulation. Dark "belts" alternate with light "zones" in the atmosphere, and scientists had long considered the zones, with their pale clouds, to be areas of upwelling air, partly because many clouds on Earth form where air is rising.
But analysis of Cassini imagery showed that individual storm cells of upwelling bright-white clouds, too small to see from Earth, pop up almost without exception in the dark belts. Other atmospheric observations included a swirling dark oval of high atmospheric-haze, about the size of the Great Red Spot , near Jupiter's north pole.
Infrared imagery revealed aspects of circulation near the poles, with bands of globe-encircling winds, with adjacent bands moving in opposite directions. The same announcement also discussed the nature of Jupiter's rings. Light scattering by particles in the rings showed the particles were irregularly shaped rather than spherical and likely originate as ejecta from micrometeorite impacts on Jupiter's moons, probably Metis and Adrastea.
On October 10, , the mission's science team announced the results of tests of Einstein's general theory of relativity , performed by using radio waves transmitted from the Cassini space probe. According to the general theory of relativity, a massive object like the Sun causes space-time to curve, causing a beam of radiowaves or light, or any form of electromagnetic radiation that passes by the Sun to travel farther. Although some measurable deviations from the values calculated using the general theory of relativity are predicted by some unusual cosmological models, no such deviations were found by this experiment.
Previous tests using radiowaves transmitted by the Viking and Voyager space probes were in agreement with the calculated values from General Relativity to within an accuracy of one part in one thousand.
The more refined measurements from the Cassini space probe experiment improved this accuracy to about one part in 51, The possible formation of a new moon was captured on April 15, Using images taken by Cassini , three new moons of Saturn were discovered in Discovery photograph of moon Daphnis. On May 1, , a new moon was discovered by Cassini in the Keeler gap.
Sent to the ringed planet to study the Saturnian system initially over a four-year period, it was the fourth spacecraft to visit Saturn and the first to enter its orbit. A total of 20 proposals were received, one of which was Cassini, under consideration for a collaborative venture with NASA and consisting of a European probe to be released into the atmosphere of Titan after being carried to Saturn by a US orbiter.
At the same time, NASA was also looking for new, more affordable missions for the s and beyond. In , NASA proposed two projects, the Planetary Observer programme and Mariner Mark II, with the latter to be a series of large spacecraft for the exploration of the outer Solar System , using a common design and hardware, much of it based on the Voyager and Galileo missions.
NASA received approval for both missions in Engage With JPL. Visit Mission Website. Mission Statistics. Launch Date Oct 15, Type Orbiter, Flyby Spacecraft. About the mission. Instruments Ion and neutral mass spectrometer Visible and infrared mapping spectrometer Composite infrared spectrometer Cosmic dust analyzer Radio and plasma wave instrument Cassini plasma spectrometer Ultraviolet imaging spectrograph Magnetospheric imaging instrument Dual technique magnetometer Radio science subsystem Imaging science subsystem Radar Descent imager and spectral radiometer Huygens atmospheric structure instrument Gas chromatograph and mass spectrometer Aerosol collector pyrolyzer Surface science package Doppler wind experiment.
Jun 30, Cassini arrives at Saturn. Dec 13, Cassini-Huygens makes its first flyby of a Saturnian moon, two in fact: Titan and Dione.
Jan 14, The Huygens probe makes its descent through Titan's atmosphere to sample the chemical composition and surface properties of the Saturnian moon. Jun 01, Cassini completes its primary mission to explore the Saturn system and begins its mission extension Cassini Equinox Mission. Sep 01, Cassini completes its extended mission Cassini Equinox Mission and begins its second mission extension Cassini Solstice Mission , which goes through and will make the first observations of a complete seasonal period for Saturn and its moons.
Dec 01, Cassini uses its synthetic aperture radar to obtain the highest resolution images yet of Saturn's moon Enceladus. Dec 01, Cassini uses its visual and infrared mapping spectrometer, or VIMS, instrument to track the transit of Venus -- a first for a spacecraft beyond Earth orbit. The exercise is to test the feasibility of using Cassini's VIMS to observe planets outside our solar system.
Mar 01, Cassini makes its last flyby of Saturn's moon Rhea, probing the internal structure of the moon by measuring the gravitational pull of Rhea against the spacecraft's steady radio link to NASA's Deep Space Network here on Earth.
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