It's only rarely that solar system exploration makes the mainstream news. Ask the person in the street which spacecraft are exploring our celestial neighbours and I doubt you'd get one correct answer, and even if you did it's probable that nobody you ask would be able to tell you what is being discovered nor its significance. Which, considering that some of these spacecraft are making monumental discoveries about the solar system and its history, is a real shame. So, help to dispel that ignorance with this Science File guide to the spacecraft currently exploring the solar system!
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Cassini |
| Origin of Name: | Named after the famous Italian-born astronomer Giovanni Domenico Cassini (1625 - 1712), who discovered the eponymous division in the rings of Saturn and was the first person to observe Saturn's moons Iapetus and several others. |
| Country / Organisation | NASA/JPL |
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Exploring: |
Saturn and its moons |
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Launch Date: |
15th October 1997 |
| Arrival Date: | 1st July 2004 |
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Duration of Mission: |
Initial mission: 4 years. Extended in 2008 by two years to become the Equinox Mission. Extended again in February 2010 to become the Solstice Mission, lasting until 2017. |
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Notable Events/Discoveries: |
In December 2004, Cassini launched the Huygens probe which landed on the surface of Titan a month later, the first time a landing in the outer solar system was accomplished. Huygens radioed back information about the surface of Titan for more than an hour and a half before succumbing to the freezing temperatures. Cassini also discovered that, as many predictions held, Titan does indeed have surface lakes of hydrocarbons, probably liquid methane. A completely unexpected discovery was that Saturn's moon Enceladus gushes fountains of ice and water vapour hundreds of miles into space from a suspected underground ocean. This water was later discovered to be the main constituent of Saturn's "E" ring. Cassini's flyby of Iapetus in September 2007 revealed an equally unexpected 20km-high ridge extending most of the way around the moon's equator. The origin of this ridge is thought to be a ring of debris surrounding the moon which crashed onto its surface. Iapetus has long been a mystery because one hemisphere is bright yet the other is dark as coal, with the dark material, where the two meet, staining the bright surface like ink blots. Thanks to images received from Cassini, scientists were finally able to put forward an explanation of the huge difference in the hemispheres' albedo: a process called thermal segregation, although there are some problems with this model. Below is a video of the Iapetus flyby put together from images returned from Cassini. Enlarge Player Embed Embed this video on your site Cassini has also revealed big differences in the composition and features of Saturn's moons and has returned a huge collection of beautiful and scientifically-important images from the Saturnian system, among which is this image of the Earth seen through the rings: just a pale blue dot.
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