Loading
Journey to Saturn – the Cassini-Huygens mission
Saturn – as research object and aesthetic eye-catcher
The Cassini-Huygens mission is one of the most ambitious space research projects ever undertaken. Launched on 15 October 1997, the American-European planetary probe journeyed through space for nearly seven years enroute to Saturn, the second-largest planet of the Solar System. The probe reached the Ringed Planet in the middle of 2004 – a journey of 3500 million kilometres. Before Cassini-Huygens' arrival, three American space probes had passed Saturn: Pioneer 11, Voyager 1 and Voyager 2. Cassini-Huygens will investigate the Saturnian system for four years.
Mission data | |
|---|---|
Launch | 15 October 1997 |
Launch mass | 5820 kilograms (including 365 kilograms payload) |
Flybys | 2 of Venus, 1 each of Earth and Jupiter |
Cassini insertion into Saturn orbit | 1 July 2004 |
Separation of Huygens probe | 25 December 2004 |
Huygens landing on Titan | 14 January 2005 |
Launch site | NASA Kennedy Space Center, Cape Canaveral, Florida, USA |
Launch vehicle | Titan IVB/Centaur |
Mission Control | NASA Jet Propulsion Laboratory (JPL), Pasadena, California, USA |
Ground stations | NASA Deep Space Network |
Data reception | No real-time operation; interim data storage in mass memory onboard Cassini with download during contact with Earth stations |
Mission end | Nominal end June 2008; extended until 15 September 2017, 13:55 CEST |
Cassini lifespan | 4 years (approx. 76 Saturn orbits) |
Cassini spacecraft | |
|---|---|
CAPS (Cassini Plasma Spectrometer) | Studied the plasma in Saturn's magnetic field (composition, origin) using three spectrometers (two ion spectrometers and one electron spectrometer). Principal Investigator: David T. Young, Southwest Research Institute, San Antonio, Texas, USA. |
CDA (Cosmic Dust Analyzer) | Analysed ice and dust particles in the Saturn system. The CDA was able to simultaneously determine the electrical charge, velocity, direction of travel and mass of individual particles and, for the first time, to determine their chemical composition. It was capable of recording up to one hit per second. The integrated High Rate Detector (HRD) could measure up to 10,000 hits per second. The CDA was developed at the Max Planck Institute for Nuclear Physics. The technology development, manufacture and suitability testing for the mechanical components of the hardware were carried out under the leadership of the System Conditioning Department at the DLR Institute for Structural Mechanics in Berlin. Mission planning and data analysis were the responsibility of the Max Planck Institute for Nuclear Physics. Principal Investigator: Ralf Srama, Max Planck Institute for Nuclear Physics, Heidelberg, Germany. |
CIRS (Composite Infrared Spectrometer) | Measured temperatures and compositions of surfaces, atmospheres and rings and consisted of three spectrometers, measuring the wavelength ranges of 7–9 microns, 9–17 microns and 17–1000 microns; the University of Wuppertal was involved in this instrument. Principal Investigator: Michael Flasar, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA. |
INMS (Ion and Neutral Mass Spectrometer) | Determined the composition of neutral and charged particles in the magnetosphere. Principal Investigator: J. Hunter Waite, Space Physics Research Laboratory, University of Michigan, Ann Arbor, Michigan, USA. |
ISS (Imaging Science Subsystem) | Provided black-and-white and colour images of Saturn’s atmosphere, rings and moons. ISS images formed the basis for most geological interpretations of the moons’ surfaces, as well as for studies of the dynamics of the rings and meteorological processes in the atmospheres of Saturn and Titan. The ISS camera consisted of two components: the NAC (Narrow-Angle Camera) with a focal length of two metres, and the WAC (Wide-Angle Camera), with a focal length of 20 centimetres. From a distance of 10,000 kilometres, the NAC provided images with a spatial resolution of 60 metres per pixel. A key focus of the DLR Institute of Planetary Research (now the DLR Institute of Space Research) in Berlin was the planning of 'target sequences' accurate to the nearest point and second, as well as the cartographic processing of image data to produce geometrically precise maps. This work was carried out in cooperation with the Cassini group at the Free University of Berlin and the Space Science Institute in Boulder, Colorado, USA. Principal Investigator: Carolyn C. Porco, Space Science Institute. |
MAG (Dual Technique Magnetometer) | Measuremed Saturn's magnetic field and its interaction with the solar wind. The University of Cologne and the Technical University of Braunschweig were involved with this instrument. Principal Investigator: David J. Southwood/Michelle Dougherty (acting), Imperial College, University of London, UK. |
MIMI (Magnetospheric Imaging Instrument) | Photographed and measured Saturn's magnetosphere through a set of three detectors. The Max Planck Institute for Solar System Research was involved in this instrument. Principal Investigator: Stamatios M. Krimigis, Johns Hopkins University, Laurel, Maryland, USA. |
RADAR (Cassini Radar) | Provided radar images and altimetry data of Titan's surface. Principal Investigator: Charles Elachi, Jet Propulsion Laboratory, Pasadena, California, USA. |
RPWS (Radio and Plasma Wave Science) | Investigated electric and magnetic fields, electron densities and temperatures. Principal Investigator: Donald A. Gurnett, University of Iowa, Iowa City, Iowa, USA. |
RSS (Radio Science Subsystem) | Searched for gravitational waves in the Universe and studied the atmospheres, rings and gravitational fields of Saturn and its moons. Principal Investigator: Arvydas J. Kliore, Jet Propulsion Laboratory, Pasadena, California, USA. |
UVIS (Ultraviolet Imaging Spectrograph) | UVIS consisted of four individual components and was capable of detecting UV light in the wavelength range from 0.056 to 0.19 micrometres. The scientists expected UVIS to provide information on the composition of Saturn’s rings and moons, as well as on the composition, photochemistry and temperatures of the atmospheres of Saturn and Titan. One of the four UVIS components, the Hydrogen-Deuterium Absorption Cell (HDAC), was developed and built at the Max Planck Institute for Solar System Research. Its task was to determine the ratio of hydrogen to deuterium (heavy hydrogen) in the atmospheres of Saturn and Titan. The DLR Institute of Planetary Research (now the DLR Institute of Space Research) was involved in software development and data analysis. Principal Investigator: Larry Esposito, University of Colorado, Boulder, Colorado, USA. |
VIMS (Visible and Infrared Mapping Spectrometer) | Carried out spectral mapping of the chemical composition and structure of the surfaces, atmospheres and rings of Saturn and its moons. VIMS recorded signals in both the visible wavelengths of light (0.35 to 1.07 micrometres) and the infrared wavelengths (0.85 to 5.1 micrometres). The instrument consisted of two spectrometers: one for visible light and the near-infrared, the other for recording the infrared spectrum. VIMS was able to map the surfaces of Saturn’s moons and rings, and the cloud cover of the planet and the moon Titan across a wide area using 352 different wavelengths. Different surface properties or substances could be identified by their corresponding wavelengths. VIMS was also able to see through the dense cloud cover of the moon Titan down to the surface (see image on the right). The wavelength range of VIMS covered a large number of ice components such as water ice, dry ice, ammonia ice and methane ice. The spectrometer was also able to identify mineral groups such as silicates, oxides and carbon, as well as other organic and inorganic materials on Saturn's moons and rings. Ralf Jaumann from the DLR Institute of Planetary Research (now the DLR Institute of Space Research) and his colleagues in the VIMS Science Team carried out the calibration of the instrument, the planning of imaging sequences and the scientific analysis of the spectrometer data. Principal Investigator: Robert H. Brown, Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA. |
Huygens Probe | |
|---|---|
HASI (Huygens Atmospheric Structure Instrument) | Studied the physical and electrical properties of the Titan atmosphere during and after landing using accelerometers, barometers and temperature sensors. The University of Cologne was involved with this instrument. Principal Investigator: Marcello Fulchignoni, University of Paris VII / Department of Space Research, Paris-Meudon Observatory, France. |
DWE (Doppler Wind Experiment) | Investigated the effect of wind on the probe using an ultra-stable carrier signal to the orbiter. Principal Investigator: Michael Bird, University of Bonn, Bonn, Germany. |
DISR (Descent Imager/Spectral Radiometer) | Carried out brightness and temperature measurements and captured images of Titan's aerosol layer, atmosphere and surface. The Max Planck Institute for Solar System Research was involved in the development of the radiometer. Principal Investigator: Marty Tomasko, University of Arizona, Tucson, Arizona, USA. |
GCMS (Gas Chromatograph Mass Spectrometer) | Determined the composition of Titan's atmosphere and aerosols using a mass spectrometer, gas collection system, gas chromatograph and a sample transport system. Principal Investigator: Hasso Niemann, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA. |
ACP (Aerosol Collector and Pyrolyser) |
Studied clouds and aerosols in Titan’s atmosphere using a sample collection system equipped with a furnace capable of heating samples to 250 degrees Celsius or 600 degrees Celsius. Principal Investigator: Guy Israel, CNRS Service d'Aéronomie, Verrières-le-Buisson, France. |
SSP (Surface-Science Package) | Investigated surface properties in the immediate vicinity of the landing site using seven subsystems to measure local acceleration, inclination, temperature, acoustics, conductivity and density. Principal Investigator: John Zarnecki, Open University, Milton Keynes, UK. |
Equal length of day and night on Saturn: the start of spring in the northern hemisphere
As the Earth, the rotational axis of Saturn, the second largest planet in the Solar System, is inclined with respect to the plane of its path around the Sun. This means that in the almost 29 (Earth) years and 164 days that Saturn requires to orbit the Sun once, there are also seasons on this celestial body. For half a 'Saturn year' – that is, almost 15 Earth years – the southern hemisphere receives the greater amount of sunlight and for 15 years the northern hemisphere is more brightly illuminated. However, the quantity of the Sun's energy that the planet receives at a distance of something over 1.4 billion kilometres from the Sun is only one ninetieth of that received on Earth. In August 2009, Saturn passed through the vernal equinox – that is, for a virtual observer on the clouds of Saturn, the Sun appeared to cross the celestial equator. The southern summer has come to an end and after 11 August 2009, when day and night were of equal length – known as the equinox – spring started in the northern hemisphere. At the time of the equinoxes, the Sun shines precisely on the edge of Saturn's rings, which surround the planet at its equator. This rather rare astronomical event is something worth celebrating – not just for observers on Earth with their telescopes – because at that time the edge of the plane of the rings is seen as a small line. For the Saturn orbiter Cassini, too, the way that the light falls across the disc at a very shallow angle offers exceptional possibilities for observation, producing special scientific results regarding the structure and dynamics of the rings. At a distance from Saturn of approximately 847,000 kilometres and a viewing angle of 20 degrees above the surface of the rings, Cassini’s wide-angle camera acquired a sequence of 75 images one-and-a-half days after the equinox in 2009, producing this image mosaic of Saturn, its rings and some of its moons. The scale of the picture is 50 kilometres per pixel. The unusual lighting geometry means that the rings appear very dark. In contrast, the structures outside the plane of the rings are unusually bright and throw long shadows across the rings. In addition, the shadows of Saturn's extensive rings appear at the equinox as a single, narrow band on the planet.
Dione in colour
Colour image of Saturn's moon Dione obtained on 11 October 2005. In this image, Saturn can be seen in blue and gold behind Dione. The horizontal stripes in the lower half of Saturn's rings are clearly seen. At the time the image was taken, Cassini was nearly level with Saturn's rings. Blue, green and infrared spectral filters were used to obtain this image. It was taken with the Wide Field Camera on board the Cassini spacecraft at a distance of approximately 39,000 kilometres from Dione. The image resolution is about two kilometres per pixel.
