CICLOPS: Cassini Imaging Central Laboratory for OPerationS

Arrival and Departure at Phoebe
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Arrival and Departure at Phoebe
PIA 18411

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  As it entered the Saturn system, NASA's Cassini spacecraft performed its first targeted flyby of one of the planet's moons. On June 11, 2004, Cassini passed Phoebe, the largest of Saturn's outer or "irregular" moons, at an altitude of just 1,285 miles (2,068 kilometers). This was the sole close flyby of one of the outer moons of Saturn in the entire Cassini mission.

This montage of two views is published by the Cassini team to mark the 10th anniversary of the Phoebe flyby.

The image on the left side shows Cassini's view on approach to Phoebe, while the right side shows the spacecraft's departing perspective. Most of the left-side view was previously released as PIA06073; an area on its upper right side is newly filled in here. Most of the view on the right side has not previously been released, although the crater at upper left is seen in PIA06074.

Phoebe's shape is approximately spherical (see PIA06070 and PIA15507 for more details), with a diameter of 136 miles (219 kilometers) on its longest axis and 127 miles (204 kilometers) on its shortest axis, which is also the rotation axis. This is approximately 16 times smaller than Earth's moon.

For several reasons, Phoebe is thought to be a captured object that does not share a joint origin with Saturn and the inner, "regular" satellites. It orbits in a retrograde direction, opposite to the direction of Saturn's other major moons. Its overall density was determined by Cassini scientists to be quite large for a moon of Saturn. The prevailing view is that Phoebe might have formed in the Kuiper Belt, far beyond the orbit of Saturn. It might thus be a small cousin of the largest Kuiper Belt object, Pluto.

The image mosaic on the left, recorded about 45 minutes before closest approach to Phoebe, is composed of six frames from Cassini's Narrow-Angle Camera (NAC), plus one Wide-Angle Camera (WAC) image to fill the gap on the upper-right limb. The image has a spatial resolution of 260 feet (80 meters) per pixel. The sun-Phoebe-spacecraft, or phase, angle is 80 degrees.

The image at right, taken about half an hour after closest approach, is composed of eight NAC frames. The spatial resolution is 210 feet (65 meters) per pixel, and the phase angle is 83 degrees.

The images have been slightly rescaled from their original formats and sharpened. Because Phoebe is a very dark object, contrast enhancement was also necessary. At such high phase angles, the brightest parts of the surface, except where bright ice is exposed, reflect only about four percent of the incoming sunlight. The mosaics are composed of monochromatic, or single-color, images. Since Phoebe is a very dark object with no obvious coloration, a natural color view would probably look somewhat similar.

The Cassini Solstice Mission is a joint United States and European endeavor. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini Solstice Mission visit http://ciclops.org, http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

Credit: NASA/JPL-Caltech/SSI
Released: June 11, 2014 (PIA 18411)
Image/Caption Information


Alliance Member Comments
jsc248 (Jun 27, 2014 at 7:39 AM):
Hi Carolyn,
I have been following these amazing images for many years from here in the UK. My own personal favourite image came from September 2005. It is of the moon Hyperion and came out under the caption of Odd World. I had to agree with that too, this amazing image could very well be of a giant sponge!! Take a look for yourselves here and tell me what you think. http://www.ciclops.org///view_media/7916/Odd-World it would be great to hear which is everyone else's favourite image from CASSINI.
Keep up the amazing images Carolyn and team. We all look forward to many more years of amazing images to come
jsc248 (John to my friends!!)
Michael1967 (Jun 12, 2014 at 1:03 AM):
Oh wow!
Incredible Images! Im looking for the next Saturn Sensation!
Nothing could top the Cassini Mission!

Go for 10 more great years of amazing pictures and informations!

Happy birthday! You could be so proud!
Greetings from Germany to the Cassini Team and to Saturn. ;-)
CARLOS R (Jun 11, 2014 at 3:02 PM):
This is so incredible! I still remember watching the live bradcast through the Internet when Cassini entered orbit around Saturn 10 years ago.
Wonderful job! Congratulations to you all Cassini team members!
kali.khelly@verizon.net (Jun 11, 2014 at 2:04 PM):
Fantastic! I had the good fortune to attend the big event in Pasadena. Those 97 minutes between communications didn't do my acrylics any good. Haven't worn them since.
Thank you for all of delightful look-sees. I look forward to the future events and moving commentary. Team, you are the BEST!
NeKto (Jun 11, 2014 at 1:27 PM):
this ride has been so much fun i didn't realise it has been going on for ten years. this is one great image in a decade long string of great images.
and more to come!

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