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Given the enormous distance between Earth and Saturn, it would have been a waste to send a spacecraft to the Saturnian region and only take a few measurements. Thus, the Cassini orbiter and the Huygens probe were equipped with an array of sophisticated instruments and cameras able to collect images in many varying conditions and light spectra; from visible light to the infrared.
After a seven-year voyage that includes four gravity-assist maneuvers, Cassini entered Saturn's orbit in July of 2004. It will then began a four-year mission that includes more than 70 orbits around the ringed planet and its moons. Pointing its various instruments at carefully calculated scientific targets, Cassini collects detailed data on Saturn, its rings and the moons orbiting this gas giant. The information will aid scientists in understanding this complex and fascinating region. Main scientific goals include measuring Saturn's huge magnetosphere, analyzing from up close those stunning rings and studying Saturn's composition and atmosphere.
Once the spacecraft's onboard recording device reaches capacity, it points its high-gain antenna toward Earth and downloads the data through one of the 70-meter (230-foot) antennas of the Deep Space Network. Cassini is sending home several gigabytes of data daily. The data is then analyzed by more than 250 scientists worldwide.
Cassini's cloud-penetrating imaging system will also be able to map Titan, Saturn's largest moon. This is a task that none of the three previous NASA missions that flew by Titan were able to do because of the thick, hazy atmosphere that engulfs this celestial body -- the only moon in the solar system with its own atmosphere.
In December 2004, Cassini ejected the Huygens probe. After its 20-day coast, the cone-shaped probe descended into Titan's cloudy atmosphere. Three sets of parachutes deployed to slow the probe and to provide a stable platform for scientific measurements. Instruments on board collected information about the atmosphere's chemical composition and the clouds surrounding Titan. The data was radioed to the Cassini orbiter, which then relayed the data to Earth.
Two hours twenty-seven minutes after entering Titan's atmosphere, the probe landed near the moon's equator. Huygens survived the impact, and was able to communicate with the spacecraft for a few minutes after landing on the frozen surface of Titan. Huygens is now the furthest human-made object ever to land on a celestial body.
Hubble Observes Surface of Titan
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[ 本帖最后由 活动星图 于 2007-2-24 05:11 编辑 ] |
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