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Cassini's mission is a four-year, close-up study of the Saturnian system, including the planet's atmosphere and magnetic field, its rings and several moons. The mission represents a rare opportunity to gain significant insights into major scientific questions about the creation of the solar system and the continuations that led to life on Earth, in addition to a host of questions specific to the Saturn system.
As the best-instrumented probe ever sent to another planet, Cassini will produce the most complete information about a planet system ever obtained.
Huygens Probe Phase
One of the Orbiter's primary missions is to transport the Huygens Probe to Saturn. During its first orbit of Saturn, it will release the Huygens Probe to coast to a landing on Titan. Once Huygens enters Titan's atmosphere and begins its descent to the surface, the Orbiter will receive and store data from the probe for transmission back to Earth. The probe does not have any propulsion systems and its transmitters are designed to communicate over relatively short distances with the Orbiter rather than Earth-based stations. The Orbiter will point its high-gain antenna at Titan during the probe's descent and store up to three hours of data. The high-gain antenna will then be pointed toward Earth and the data stored on solid-state recorders will be transmitted to Earth at times when the Orbiter is visible from one of the Deep-Space Network (DSN) ground stations.
Four-Year Tour
After the end of the probe mission phase, the Saturn Orbiter will start its four-year tour of the Saturnian systems, the so-called satellite tour. This consists of more that 40 Saturn-centered orbits, connected by Titan gravity-assist flybys or propulsive maneuvers. Equipped with 12 scientific instruments, the Saturn Orbiter will measure the planet's magnetosphere, atmosphere, and rings, and observe Titan and some of the icy satellites during close flybys.
Saturn Orbiter Design
The Orbiter weighs 12,423 lb. (5,634 kg) including the Huygens Probe at 776 lb. (352 kg); 739 lb. (335 kg) of science experiments; the launch adapter and 6906 lb. (3,132 kg) of propellant
The Orbiter science instruments are mounted on two body-fixed platforms; the remote-sensing pallet and the particle and field pallet. The Magnetometer is mounted at the tip of an 26.2 ft (8 m) long boom; the magnetic and electric antennas of the Radio and Plasma Wave Sciences (RPWS) are mounted on the body; both the radar and the Radio Science Subsystem (RSS) use the high-gain antenna.
To power Cassini, there are three plutonium-powered Radioisotope Thermoelectric Generators (RTGs) that convert heat from decaying radioactive plutonium into electricity. While NASA is seeking alternatives to the use of nuclear power in space, solar power is not a viable alternative due to the great distance from the Sun, batteries are too heavy and fuel cell technology is undeveloped.
Inertial reference for the Cassini mission will be entrusted to the first space version of a revolutionary new gyro with no moving parts. The Hemispherical Resonator Gyroscope was developed and produced by Delco/Hughes. This new gyro promises greater reliability and less vulnerability to mechanical failure because it uses no moving parts. Another new device with no moving parts is the solid-state data recorder which will store data from Huygens and other instruments.
The Cassini Orbiter's main computer uses a novel design, which draws upon new families of electronic chips -- very high-speed integrated circuit (VHSIC) chips developed under a U.S. government/industry research and development initiative for dual-use technology. The Cassini application GVSC 1750A computer is the first civilian spacecraft application of this technology.
The Magnetosphere Imaging Instrument (MIMI) will obtain images of the plasma and radiation surrounding Saturn and enveloping its moons, including Titan. MINI will observe the glow of Titan's exosphere due to the bombardment by high-speed protons trapped in Saturn's magnetic field. This pioneering investigation will open a new observation window in the study of planetary magnetic fields, including Earth's
For the latest developments and news on the mission visit:
NASA - National Aeronautics and Space Administration
ESA - European Space Agency
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