Cassini-Huygens spacecraft : Solar System Exploration
The Cassini-Huygens spacecraft is one of the largest, heaviest, most complex interplanetary spacecraft and one of the most ambitious efforts ever mounted in planetary exploration. It was a joint mission of NASA, European Space Agency (ESA) and the Italian space agency (ASI). Cassini’s main mission was to study Saturn and its complex system of rings and moons of Saturn in unprecedented detail. In the late 1970s and early 1980s, three spacecraft, Pioneer 11 and Voyager mission was launched who completed flybys of Saturn. It retured stunning images and information about the Saturn planet, its rings, and numerous satellites during journey. But new information about Saturn just raised more questions and made scientists more eager to observe Saturn. This eager to know more about Saturn planet, Saturn moons and its ring system made the foundation of cassini-huygens Saturn mission.
Cassini Huygens spacecraft was named after Dutch scientist Christiaan Huygens (1629-1695) and Italian scientist Jean-Dominique Cassini (1625-1712). Christiaan Huygens was the first person who discovered Saturn’s rings and, in 1655, its largest moon, Titan. Jean-Dominique Cassini discovered narrow gap separating Saturn’s rings which is known as ‘Cassini Division‘ today and moon of Saturn Iapetus, Rhea, Tethys and Dione.
The Cassini orbiter was built by Jet Propulsion Laboratory of NASA. Other equipment like high-gain antenna and other radio subsystem was built by the Italian Space Agency (ASI) under a bilateral NASA/ASI agreement. Huygens probe, and the associated communications equipment on the orbiter, was built by European Space Agency.
- To Study cloud properties and atmospheric composition, winds and temperatures, internal structure and rotation, ionosphere, origin and evolution of Saturn.
- To Observe the structure and composition, dynamical processes, interrelation of rings and satellites, dust and micrometeoroid environment.
- To Study abundances of atmospheric constituents, distribution of trace gases and aerosols, winds and temperatures, composition and state of the surface, and upper atmosphere of Titan.
- To determine their characteristics and geological histories of Icy Satellites and to study mechanisms of surface modification, surface composition and distribution, overall composition and internal structure, and their interactions with Saturn’s magnetosphere.
- To study, structure and electric currents; composition, sources and sinks of particles within it; dynamics; interaction with solar wind, satellites and rings; Titan’s interaction with solar wind and magnetosphere.
The Cassini-Huygens spacecraft was launched by a U.S.Titan IV-B launch vehicle which was the largest and most powerful expendable launch vehicle at the time of launch. It was two-stage, liquid propellant booster rocket, two strap-on solid rocket motors, a Centaur upper stage and payload fairing. Although it most powerful expendable launch vehicle available, still wasn’t powerful enough to send the massive Cassini-Huygens on a direct path to Saturn planet. So spacecraft relied on several gravity assist maneuvers to achieve the required velocity to reach the ringed-planet. This 7-year journey took it past Venus twice, and once the Earth and Jupiter, to gain velocity by flyby from these planets to reach Saturn.
Flyby of Venus
On April 26, 1998, Cassini-Huygens completed its first flyby of Venus at a distance of 176 miles from the surface. Science instruments on the spacecraft searched for lightning in Venus’ atmosphere during the flyby, and the radar instrument on board was activated to test a signal bounced off the planet’s surface. Cassini-Huygens spacecraft completed its second Venus gravity-assist flyby on June 24, 1999, this time at a distance of 370 miles.
Flyby to Earth
On 18, August 1999, Cassini-Huygens spacecraft completed its Flyby of our home planet within 728 miles of its home planet surface and 234,000 miles of Earth’s Moon.
Flyby to Jupiter
The spacecraft completed its final flyby of Giant planet Jupiter within 6,122,323 miles on Dec. 30, 2000. Cassini-Huygens spacecraft conducted joint science observations of the planet with the Galileo spacecraft in orbit around Jupiter at the time.
Arrival at Saturn
On July 1, 2004, Cassini fired its main engine for 96 minutes and entered an elliptical orbit around planet Saturn. It became the first spacecraft to do so. From here the incredible 13-year in-depth exploration of the planet began, its rings and its satellites, with scores of remarkable discoveries. In first few months, Cassini completed three flybys of Titan and discovered two additional moons orbiting the ring planet. It took the first close-up photo of Saturn’s outer moon Iapetus on Dec. 30, 2004, with a long mountain range. During the Saturn Orbit Insertion spacecraft approached Saturn from below the ring plane, through the large gap between the F-Ring and G-Ring. At the time Cassini-Huygens spacecraft was 158500 km from the centre of Saturn. Cassini-Huygens spacecraft’s closest approach to Saturn occurred during the burn at a distance of approximately 0.3 Saturn Radii (20000 km).
Titan Surface Landing
On December 24, 2004, Huygens probe separated from Cassini orbiter. On 14 January 2005 Huygens probe successfully landed on the surface of Titan with the help of parachute. It became the first space probe to land on an object in the outer Solar System. The descent to the surface of Titan lasted 2 hours and 27 minutes. During this period Huygens’ instruments analyzed the atmosphere and returned images of the surface to Earth via the Cassini orbiter. Huygens probe continued to return data for another 72 minutes from the surface of Titan until Cassini dropped below the horizon and could no longer relay the probe’s signals. The Huygens probe analyzed Titan’s surface and returned 376 images during the descent and from the surface.
Cassini – Huygens Spacecraft Characteristics
|Dry mass (orbiter only)||2125 kg|
|Launch mass (orbiter, Huygens probe, |
launch vehicle adapter, fuel)
|Power (beginning of mission)||885 W|
|Power (end of nominal mission)||633 W|
Huygens Probe Instruments
|ACP||Aerosol Collector and Pyrolyser|
|DISR||Descent Imager and Spectral Radiometer|
|DWE||Doppler Wind Experiment|
|GCMS||Gas Chromatograph and Mass Spectrometer|
|HASI||Huygens Atmospheric Structure Instrument|
|SSP||Surface Science Package|
Cassini Orbiter Instruments
|CAPS||Cassini Plasma Spectrometer|
|CDA||Cosmic Dust Analyzer|
|CIRS||Composite Infrared Spectrometer|
|INMS||Ion and Neutral Mass Spectrometer|
|ISS||Imaging Science Subsystem|
|MAG||Dual Technique Magnetometer|
|MIMI||Magnetospheric Imaging Instrument|
|RPWS||Radio and Plasma Wave Science|
|RSS||Radio Science Subsystem|
|UVIS||Ultraviolet Imaging Spectrograph|
and Infrared Mapping Spectrometer
Some Discovery by Cassini
1. Active icy plumes on the Enceladus ( Saturn’s moon )
The discovery of massive plumes of liquid water spewing into space through cracks in the icy surface of Saturn’s moon Enceladus was one of the biggest surprise.Due to this plumes of liquid from the surface, mission designers completely reshaped the mission to get a better look.
2. Revealing Earth-like world with rain, rivers, lakes and seas
The Huygens space probe found evidence of oceans of liquid water on some of the moons, spotted geysers and other geologic activity, and even found indications of prebiotic chemistry. These processes generate methane rains on moons, which build river channels and form lakes and seas containing liquid methane and ethane that don’t immediately evaporate.
3. The Huygens Space probe makes first landing on a moon in the outer solar system (Titan)
The Huygens probe lander made landing on the surface of Titan on Jan. 14, 2005. During the probe’s 2-hour and 27-minute descent revealed Titan to be remarkably like Earth before life evolved, with methane rain, drainage channels and dry lake beds.
4. Saturn’s rings revealed as active and dynamic
From earth the rings of Saturn look static if observe through a small telescope. But in reality sea of particles and small rocks are constantly changing. Cassini orbiter observed evidence of collisions in Saturn’s rings from meteoroids, or small bodies that originate somewhere out of Saturn’s system. The F ring is one of the most active rings ever observed because the features observed in the F ring by the Voyager probes in 1980 and 1981 had disappeared by the time Cassini began studying the ring system
6. The Hexagon Storm
At Saturn, Cassini examined a hexagonal-shaped jet stream at the Saturn’s north pole, with a swirling vortex at its center. Cassini’s observations confirmed existence of storm on Saturn with two huge storms at both poles that resemble hurricanes.
7. Discovering multiple moons of Saturn
Saturn hosts 53 known moons and another 29 moons are awaiting confirmation of discovery and official naming. When the mission began in 1997, scientists only knew of 18 moons around Saturn. But after mission began Cassini uncovered the tiny moons of Methone and Pallene, followed up by discoveries of moons such as Polydeuces, Daphnis and Aegaeon.