The Cassini spacecraft is scheduled to make a close flyby of Saturn's moon Iapetus tomorrow. As it flies less than a thousand miles from Iapetus, which will be the closest approach to date, it will tae a look at look at the long, narrow ridge along the moon's equator and image the dark side. The ridge is about 12 miles wide, eight miles high and stretches a third of the way around the moon.
This map of Iapetus, was generated from images taken by the Cassini and Voyager spacecraft. The map illustrates the imaging coverage planned for Cassini's very close, and only, flyby of the moon on Sept. 10, 2007.
At closest approach, Cassini will be 1,640 kilometres above the surface of Iapetus. The spacecraft will pass the moon at a speed of about 2.4 kilometres per second.
On Sept. 10, the Cassini spaceprobe make a close flyby of Iapetus, coming about 1,640 kilometres from the moons surface. Iapetus has a leading hemisphere that is as dark as tar, and a trailing hemisphere that is as white as snow. During the fly by, scientists hope to learn more about the composition of the dark material that coats Iapetus.
There's a strange moon whizzing around Saturn that's shaped, oddly, like a walnut. Now astronomers find that Iapetus got its nutty shape from a super-fast spin that was frozen into place early in the solar system's formation. When the Cassini spacecraft snapped close-ups of Saturn's moons in 2005, it revealed a bulging waistline of rock along the equator of the now slowly spinning Iapetus. Astronomers think this characteristic shape persists because Iapetus was cryogenically frozen in time about 3 billion years ago, during the moon's "teen" years.
Saturn's distinctive moon Iapetus is cryogenically frozen in the equivalent of its teenage years. The moon has retained the youthful figure and bulging waistline it sported more than three billion years ago, scientists report.
"Iapetus spun fast, froze young, and left behind a body with lasting curves" - Julie Castillo, Cassini scientist at NASA's Jet Propulsion Laboratory, Pasadena, California.
Unlike any other moon in the solar system, Iapetus is the same shape today as it was when it was just a few hundred million years old; a well-preserved relic from the time when the solar system was young. These results appear in the online version of the journal Icarus. Cassini flew by Iapetus in early 2005 and discovered the moon had a walnut shape, bulging at its midsection. On top of that it has a chain of mountains located exactly along its equator. Scientists now think the moon's bulging midriff and slow spin rate point to heating from long-extinct radioactive elements present when the solar system was born.
This natural colour image of Iapetus was taken by the Cassini spaceprobe during a flyby on April 15, 2007. The view looks toward Iapetus from about 24 degrees above the moon's equator.
Expand (34kb, 560 x 435) Credit: NASA/JPL/Space Science Institute
Images taken using red, green and blue spectral filters were combined to create the image. The images were taken with the Cassini spacecraft narrow-angle camera at a distance of approximately 2.3 million kilometres from Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 66 degrees. Scale in the original images is 13 kilometres per pixel. The view has been magnified by a factor of three.