NASA’s Cassini spacecraft is to conduct a close fly-by of Titan, Saturn’s largest moon, on July 7. The craft will swoop to within 1,005 kilometres of the cloud-covered world, shooting past at a speed of 5.9 km per second (21,240km/h or 13,000mph).
During the close approach, instruments will study the chemical make-up of its atmosphere, while Cassini’s radar will scan a poorly-covered region of the moon. Other instruments will keep an eye on clouds in Titan’s atmosphere.
Ice world with a thick atmosphere
In many respects Saturn’s largest moon is one of the most Earth-like worlds found to date. With its thick atmosphere and organic-rich chemistry, Titan resembles a frozen version of Earth, several billion years ago, before life began pumping oxygen into our atmosphere.
Titan is of great interest to scientists because it has a substantial, active atmosphere and complex, Earth-like processes that shape its surface. The moon is enveloped by an orange haze of naturally produced photochemical smog that frustratingly obscured its surface prior to Cassini’s arrival. Since 2004, the spacecraft’s observations have taken the study of this unique world into a whole new dimension.
Cassini has revealed that Titan’s surface is shaped by rivers and lakes of liquid ethane and methane (the main component of natural gas), which forms clouds and occasionally rains from the sky as water does on Earth. Winds sculpt vast regions of dark, hydrocarbon-rich dunes that girdle the moon’s equator and low latitudes. Volcanism may occur as well, but with liquid water as the lava.
First landing in the outer Solar System
On its journey to Saturn, Cassini carried the European-built Huygens probe. On January 14, 2005, Huygens achieved humankind’s first landing on a body in the Outer Solar System when it parachuted through Titan’s murky skies. Huygens took measurements of atmospheric composition and wind speeds during its decent, along with an incredible series of images showing telltale patterns of erosion by flowing liquid. The probe came to rest on what appeared to be a floodplain, surrounded by rounded cobbles of water ice.
As the now-renamed Cassini Equinox Mission progresses, the spacecraft will monitor Titan’s atmosphere and surface for signs of seasonal change. The spacecraft’s radar and camera systems will continue to peer through the haze, expanding high-resolution maps of the surface. And scientists will eagerly await new data that could confirm the presence of a liquid ocean beneath the giant moon’s surface.
Adapted from information issued by NASA / JPL / Space Science Institute / ESA / University of Arizona / S.M. Matheson.
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