Raindrops on Titan.Sporting an atmosphere denser than that of any other moon known in the solar system solar system, the sun and the surrounding planets, natural satellites, dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity. The sun is by far the most massive part of the solar system, containing almost 99.9% of the system's total mass. , Titan, Saturn's largest satellite, has long intrigued astronomers Famous astronomers and astrophysicists include: Directory: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A
Little wonder, then, that planetary scientists look forward to 1997, when NASA NASA: see National Aeronautics and Space Administration. NASA in full National Aeronautics and Space Administration Independent U.S. and the European Space Agency European Space Agency (ESA), multinational agency dedicated to the promotion, for exclusively peaceful purposes, of cooperation among European states in space research and technology. plan to launch the Cassini/Huygens mission to Saturn and its moons. The mission's mother ship will orbit Saturn, while the Huygens probe The Huygens probe, supplied by the European Space Agency (ESA) and named after the Dutch 17th century astronomer Christiaan Huygens, is an atmospheric entry probe and lander carried to Saturn's moon Titan as part of the Cassini-Huygens mission. will parachute through Titan's thick cloud layer, giving astronomers their first glimpse First Glimpse is a monthly consumer electronics magazine published by Sandhills Publishing Company in Lincoln, Nebraska, USA. The magazine was known as CE Lifestyles before a name change in early 2006. at the surface of this icy satellite. In designing the probe, some scientists have worried that methane droplets in Titan's lower atmosphere could freeze on the instrument, much the way unwanted ice crystals can form on the body of an airplane in winter. Methane "rain" that formed ice deposits on the Titan probe for an extended period could obscure the probe's camera lens and damage the instrument. Ralph D. Lorenz, a graduate student at the University of Kent at Canterbury, England, and a former engineer on the probe project, now reports that the freezing rain Freezing Rain is a type of precipitation that begins as snow at higher altitude, falling from a cloud towards earth, melts completely on its way down while passing through a layer of air above freezing temperature, and then should not cause problems. Previous calculations by other researchers, based on Voyager data, indicate that the surface of Titan has a temperature of about 99 kelvins. Lorenz reports that this chilly temperature is nonetheless warm enough to melt the frozen methane rapidly once the probe descends below 14 kilometers in the atmosphere. Lorenz also calculates that liquid methane in the clouds could form raindrops as big as hazelnuts -- some 9 millimeters across. Such drops are about 50 percent bigger than the largest water raindrops on Earth. But any rain on Titan would far more softly because of the satellite's denser atmosphere and lower gravity. For example, he notes, a raindrop on Earth might take a minute to fall 1 kilometer, but a methane drop on Titan would require nearly an hour. |
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