© NASA/JPL/Space Science Institute Exploring Saturn Cassini Huygens is an international collaboration between NASA, the European Space Agency (ESA) and the Italian Space Agency (ASI) to explore Saturn and its largest moon, Titan. Cassini arrived at Saturn on 1st July 2004. Saturn is a gas giant, composed mainly of hydrogen and helium. With its famous ring system, a plethora of moons and one of the most complex magnetospheres in the Solar System, Saturn is a fascinating target. What is ? Cassini Huygens Cassini Huygens The mission is made up of the Cassini spacecraft, which is in orbit around Saturn, and ESA’s Huygens probe, which landed on Titan. It was launched in October 1997. The mission is named after two 17th Century astronomers: Jean Dominique Cassini, the discoverer of four of Saturn’s moons, and Christiaan Huygens, who discovered Titan and realised that the “ears” Galileo had observed either side of Saturn were actually rings. UK involvement in Cassini Imperial College London leads the team behind Cassini's MAG instrument, which is monitoring Saturn's magnetic field. British scientists are also involved in Cassini's cameras and experiments to monitor Saturn's and Titan’s atmospheres, plasma environment and dust in the Saturnian system. They also carried out extensive theoretical modelling work to support the mission science. UK involvement in Huygens The UK’s Open University, supported by the Rutherford Appleton Laboratory, built the Surface Science Package, which consisted of nine instruments to measure the properties of Titan’s surface after landing. The Open University also provided the high sensitivity accelerometers which enabled the high altitude properties of the atmosphere to be measured with great precision. Cassini Huygens launch Cassini spacecraft © NASA/Kennedy Space Center © Courtesy NASA/JPL-Caltech Christian Huygens © Smithsonian Institution Libraries, Washington, DC Jean Dominique Cassini Low-Gain Antenna (1of 2) • Radar Bay Fields and Particles Pallet Hygens Titan Probe Radioisotope Thermoelectric Generator (1 of 3) Remote Sensing Pallet • Radio/Plasma Wave Subsystem Antenna (1 of 3) 11m Magnetometer Boom • High Gain Antenna • 445 N Engines The initial four-year mission follows a complex orbital path, allowing the spacecraft to view the planet and its surroundings from different distances and angles. Highlights have been close flybys of many of Saturn’s moons, producing spectacular pictures, and a wealth of discoveries, including new rings, additional moons, a radiation belt, massive mountains and probable lakes of methane and ethane on Titan and ice geysers on Enceladus. An extension to the mission is currently being planned. Phoebe © NASA/JPL/Space Science Institute © NASA/JPL/Space Science Institute © NASA/JPL/Space Science Institute Titan Portrait of Saturn by Cassini © NASA/JPL/Space Science Institute Saturn’s Rings On 14th January 2005, the Huygens probe descended through Titan’s atmosphere to discover what lay beneath the opaque, orange haze. It revealed a landscape that was both familiar and alien. Low-lying hills formed from water-ice bedrock were patterned with river channels and lake beds possibly carved by liquid methane rain. Huygens landed on an undulating surface covered with ice pebbles. Data from the impact suggests that the probe bounced off a pebble before settling on a surface that reacted like lightly packed snow or damp sand. Huygens did not detect standing or running liquid, but it found the atmosphere at the surface, and probably the surface itself, was ‘moist’ with liquid methane. During the descent, which lasted 2 hours and 28 minutes, the probe measured the physical and chemical properties of Titan’s atmosphere. It confirmed that nitrogen and methane were the most common gases and that, unexpectedly, the methane “haze” was present right down to the surface. An isotope of argon was detected at the surface, which together with the high concentrations of methane, suggests that Titan has ongoing volcanism. Above left: Artist’s impression of Huygen Probe Above: Titan’s surface Right: Colour view of Titan’s surface Left: Mosaic of river channels Images © ESA/NASA/JPL/University of Arizona Further Information If you would like to know more about the Cassini Huygens mission, try the following resources: World Wide Web sites saturn.jpl.nasa.gov sci.esa.int - missions - Cassini Huygens www.uk2planets.org.uk www.nineplanets.org Books Ralph Lorenz & Jaqueline Mitton Lifting Titan’s Veil Cambridge University Press, 2002 David M Harland Mission to Saturn: Cassini and the Huygens Probe Springer Praxis, 2002 Fredric W. Taylor The Cambridge Photographic Guide to the Planets Cambridge University Press, 2001 Cover image: Saturn Approach by Cassini The Science and Technology Facilities Council operates world-class, large-scale research facilities; supports scientists and engineers world-wide; funds researchers in universities and provides strategic scientific advice to government. The Council’s Science in Society unit offers a wide range of support for teachers, scientists and communicators to facilitate greater engagement with STFC science which includes astronomy, space science, particle physics and nuclear physics: For Schools • Free Publications and resource guides suitable for teaching ages 10-18. Go to www.scitech.ac.uk - Public and Schools - Schools and Education - Resources • Funding schemes for projects and school visits. Go to www.scitech.ac.uk - Public and Schools - Funding • A Moon rock and meteorite loan scheme. Go to www.scitech.ac.uk - Public and Schools - Schools and Education - Loan Scheme • Visits to STFC’s UK laboratories in Cheshire, Oxfordshire and Edinburgh plus CERN in Geneva. Go to www.scitech.ac.uk - Public and Schools - Visits and Events • Researchers in Residence. Teachers are placed in partnership with young scientists who have been trained to support the teacher, act as role models and introduce their research. Go to www.researchersinresidence.ac.uk. For Scientists • Communication and media training courses; funding schemes and Fellowships for public engagement. Go to www.scitech.ac.uk - Public and Schools - Fellowships and Communications Training For further information telephone 01793 442175 or email [email protected]