Rev 149 - May 30-Jun 29, 2011 - Helene, Distant Iapetus, mutual events Options

[machi]

"Anyone know if VIMS also got images?"

It's highly probable. VIMS worked together with ISS almost every close flyby . This was for example case of last Helene flyby and
results has similarly bad alignment.

Attached thumbnail(s)

 

[pat]

Anyone know if VIMS also got images?

Yes, VIMS was on as was UVIS and CIRS

[tasp]

Anyone else reminded of Clarke's novel, A Fall of Moondust ?

[toddbronco2]

Eyes on the Solar System has predicted trajectory (but not pointing) for this - and looking at the geometry, I think it's the limb of Saturn, The 'darkness' you have, is the night side of Saturn. C/A was well after that and the dark side of Saturn was no longer in the FOV.

Yes, the bright patch definitely is the Saturnian limb. Coincidentally, the limb is right at the terminator too.

[ugordan]

High phase Titan, WAC & NAC red+blue composites:

[eoincampbell]

High praise for that high phase... WOW !

[ElkGroveDan]

Stanley Kubrick would be envious.

[algorimancer]

[attachment=24564:Rhea_Titan.jpg]

The really cool thing about that (really nice) stereo view is that even the polar haze on Titan stands-out (though I'm not sure it's not an artifact).

[Ian R]

The distant view from January essentially shows the same side of Helene, albeit illuminated from the opposite angle:

http://photojournal.jpl.nasa.gov/catalog/PIA12758

Now, the caption states that this is the trailing hemisphere, which I *think* is a mistake; the 'Eyes on the Solar System' simulation and the mini-atlas suggest that this is actually the leading hemisphere.

Here are two shots from the January and June flybys side-by-side:



...and here is a rough version of the two combined, showing the entirety of the leading hemisphere:

[machi]

Fantastic finding!
From this angle Helene looks like heart, what it is not very surprising, when one come to realize, that Helen was beautiful Troy's princess.

[dilo]

...and here is a rough version of the two combined, showing the entirety of the leading hemisphere:

Great finding, I made another version with different hue illuminations (some distorsion in the polar regions of older image was necessary in order do better match features, probably due to slight difference in the Cassini "latitude"):

What an incredible body!

[Phil Stooke]

Very nice, Dilo!

Phil

[Ian R]

I concur with Phil: Dilo, that was a really good idea to colourise the two halves in different hues; both informative and eye-catching!

Phil, as an expert in small heavenly bodies, do you agree that this is indeed the leading hemisphere of Helene?

[pjam]

Great finding, I made another version with different hue illuminations (some distorsion in the polar regions of older image was necessary in order do better match features, probably due to slight difference in the Cassini "latitude")

Beautiful composite!

Note that the darker surface that appears to be eroding into the lighter gullies has some relief: The darker surface is exposed mostly in the ridges and appears competent -relative to the gullies it has been around for awhile.
Perhaps this implies that if the leading surface of Helene is being coated, it is not a continuous process but is instead episodic. If a `weathering' rate could be determined then a limit on the age of the last `coating' event could be estimated.
-pjam

[Ian R]

This flyby made me go back and take another look at the images Cassini took from last year's encounter. I decided to stack the Saturn-shine pictures, resulting in a reasonable enhancement of the facing hemisphere: