Friday, July 29, 2005

New Enceladus Image: Warm Fractures on Enceladus

CICLOPS and the Composite InfraRed Spectrometer (CIRS) team have released this view of Enceladus in coordination with today's press release. During the flyby on July 14, CIRS took spectral measurements at wavelengths between 9 and 16.5 microns to measure the surface temperature of Enceladus, often coinciding with images taken by ISS. A string of ride-along measurements are shown here, superimposed on a ISS false color image taken at the same time as the measurements. The boxes represent the location of the measurements and the numbers above represent the temperature measured in Kelvin. Most of the surface was found to be in the expected range of 75K, however regions in the south polar ridged terrain showed higher temperatures. A couple of measurements, seen here, were a much higher temperatures, between 87 and 91 Kelvin, which is difficult (but not impossible) to explain by solar heating. When looking at the color temperatures measured, which looks at the shape of the spectrum seen by CIRS to determine the temperatures of several sub-pixel components. A two-temperature fit to the spectrum results in at least 1 percent of the 91 K pixel having a temperature of 140 K, further supporting the hypothesis that the increased temperatures seen over this area of the tiger stripes is caused by heat escaping from Enceladus' interior.

The ISS view is a false color version of the clear filter image released earlier this week and has a resolution of 122 m/pixel. This image uses an ultraviolet filter for blue, the clear filter for green (the normal green filter image was summed), and a near-infrared filter for red. The area surrounding the tiger stripe fracture is thought to be bluer because of coarse-grained water ice that has not been covered by the fine-grained ice that has painted the rest of Enceladus' surface.


Anonymous Anonymous said...

Could the blue color indicate crystalline ice? A temperature of 110K is required to form crystalline ices and that may hold in the maw of those vents.

The process to form crystalline ices with cryovolcanic outgassing is known on the satellites of Uranus and spectral analysis of Quaoar (a Kupeir Belt object) suggests that the same process is probably at work there. (See the article on Quaoar at the Kupier Belt page.

High resolution spectral analysis would show the the nature of the ices for sure. Has that or will that be done?

7/29/2005 05:56:00 PM  
Blogger Jason said...

The "blue" colored ice has been determined to be caused by coarse-grained water ice.

7/29/2005 06:22:00 PM  
Anonymous Michael Adams said...

I had made this animation back in February from images taken from the Cassini flyby of Enceladus that month. At the time, I brought this image to your attention, and you and the rest of the imaging team thought that what I assumed to be jets/geysers erupting from the moon's south pole were imaging artifacts. Have you revisited these images to see if you still think that's the case, or if Cassini captured the ice release in the act?

7/29/2005 11:44:00 PM  
Blogger Jason said...

nope, still an image artifact. But it is an interesting coincidence.

7/30/2005 08:30:00 AM  

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