The Planetary Society Blog
By Emily Lakdawalla
Cassini moves on to Rev 18 and captures lots of Iapetus images
Nov. 15, 2005 | 12:08 PST | 20:08 UTC
Just a couple of days ago the odometer tipped over to Rev 18 on Cassini's nearly-80-orbit tour. Since November 1 Cassini has been performing daily observations of Iapetus -- the orbits of Iapetus and Cassini lined up so that Cassini was near Iapetus' orbital position at just about the same time it reached its farthest orbital apoapsis for many months, more than 27 times Saturn's diameter away from the planet. Since Iapetus orbits at 30 times Saturn's diameter away from Saturn, that put Cassini in the right spot for a flyby that you can't call "close" but is close enough for better imaging than Voyager ever got. The closest-approach distance was around 416,000 kilometers on November 12. And because Cassini and Iapetus were traveling in the same direction and moving with relatively slow speed with respect to each other, the encounter has been a very leisurely one, allowing Cassini to grab lots and lots of images and spectral data. Here's a quick composite I put together of three images taken from the JPL raw images website: Iapetus in colorA composite of red, green, and blue images from Cassini's November 12, 2005 approach to Iapetus shows two of the giant impact basins in Iapetus' dark Cassini Regio. The crater on Iapetus' day-night boundary is named Roland. The view is principally of the northern and leading hemispheres of Iapetus. Credit: NASA / JPL / Space Science Institute / Emily Lakdawalla |
The three images were all taken at very close to the same distance from Iapetus (418,864 km for the red and 418,834 for the blue and green) so they line up with each other to make the color composite very nicely. However, the color balance was just a guess; the correct coloration will have to wait for an image product to be released by the Cassini imaging team. I have also posted a page of representative images from every observation made during this encounter.
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