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

[charborob]

Latest Looking ahead article (Rev149: May 30 - Jun 29) is up.
- Iapetus observations
- Titan-Rhea mutual event
- close (6,968 km) flyby of Helene
- Titan flyby
Interesting stuff.

[ugordan]

A rare view of Iapetus, slight high-pass filter applied to reduce glare in the sunlit ice:

[Juramike]

Image of Saturn on June 4, 2011. Assembled from CB2, GRN, and BL1 images:

[charborob]

Lots of Iapetus images have been posted on Cassini's raw image page here.

[ugordan]

Iapetus' double impact basin front-n-center. June 7th, IR1/GRN/UV3.

[ngunn]

Much appreciated Gordan. It's great to see the old walnut moon again, and from a new angle.

[Explorer1]

Has any new terrain been revealed in this view? Obviously it isn't the best resolution, but just out of curiosity.

[Ian R]

Imagine if you could rock Iapetus back and forth in your hand... well, this is the next best thing:

http://youtu.be/qY2DMMak5L8?hd=1

[charborob]

I downloaded all the flyby images this morning with the idea of assembling an animation if I find the time, but I think I'll just enjoy what has been done already.

[ugordan]

Another random snapshot from the Iapetus sequence, June 9th, IR1/GRN/UV3:



"Snowman" craters coming into view at the limb to the left.

[Ian R]

Great as per usual, Gordan.

I've updated my Iapetus 'bouncy' flyby movie, which is derived from a sequence of 203 frames; tweened to 406:

http://youtu.be/qY2DMMak5L8?hd=1

[CAP-Team]

as for Iapetus, my only wish would be to have high-res image - in daylight - of the snowman craters..

[Decepticon]

Its sad we don't get anymore closer flybys.

I'll take anything we can get.


Ian amazing work!

[Juramike]

Methanovision composite [MT3,MT2,CB2] with an overlaid CB2 image to enhance cloud detail taken on June 11, 2011:

[Leither]

Mike, another fantastic composition - such beauty! Keep up the great work!

[Juramike]

Two frame blink animation of two MethanoVision [MT3,MT2,CB2] composites from June 13, 2011. Some neat storm structures. It is subtle, but a counterclockwise motion can be seen in the left swirl looking at the inner cloud motions.



(Individual frames and processing details on flickr)

[Juramike]

June 14, 2011 image. Not this might be similar (1 or two rotations?) to the view seen above. Note a new upwelling to the W of the bright little (cute!) cloud swirl.



If so, that makes three seperate upwellings in a line.

[ugordan]

I can haz mutual event?

http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=238919
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=238924
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=238928
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=238938

[elakdawalla]

Oo, now they're getting all fancy with their camera angles. I assume that they did that technically to take advantage of the diagonal of their square FOV being 1.4 times longer than the path straight across...but it doesn't hurt that it looks cool!!

[charborob]

Until someone makes an animation of this mutual event, here's a quickly trown together cross-eyed 3D view of the encounter.

[ilbasso]

I had lunch with Carolyn Porco a couple of weeks ago and asked her about these "tourist" photos - i.e., was there valuable scientific data being obtained or was it sightseeing? She said that she actually has quite a fondness for these kinds of beautiful images. They add so much to the perception of the Saturn system as a "place," and so they are planned even though there is really no scientific data to be gleaned from them. I suspect that the positive PR impact gained from these sightseeing photos certainly is worth the hydrazine to aim the camera.

[ugordan]

Don't go around looking for any alien bases, you might find them...

[nprev]

....that is drop-dead gorgeous, Gordan!!!

[lyford]

SUH-WEET!

[Astro0]

Until someone makes an animation...

Well, not exactly an animation but a 15 second movie based on the Cassini images.
 Rhea_Titan.wmv ( 854.28K ) Number of downloads: 847

or on YouTube.

Enjoy

[eoincampbell]

Astro0, very moving

[ugordan]

Very nice and seamless, Astro0!

[Ian R]

Holy Smokes!

[ugordan]

Wow, they totally NAILED it this time!

[antipode]

Holy smokes! Downslope flow features?

P

[Ian R]

[Ian R]

[The Singing Badg...]

Wow. These tiny moons never fail to bewilder.

[SFJCody]

... that's a pretty astonishing little body. The solar system seems to have an endless supply of surprises.


I guess this is the face that launched a thousand [space]ships. Or a thousand excited exclamations of a word that sounds like ship.

[ugordan]

RGB composites, one in natural-ish contrast and another contrast-enhanced:



The illuminated hemisphere seems to be the same one as the saturnshine-lit one in this image.

I think this is my favorite of the small Saturnian rocks.

[Ian R]

I'm posting a link to my Helene 'mini-atlas' for reference:

http://www.flickr.com/photos/10795027@N08/...57624830467026/

[Bjorn Jonsson]

Wow. Yet another object in the Saturn system that qualifies as one of the strangest ones I've ever seen. Maybe it's becoming necessary to redefine what strange means in this context because the 'stereotype' small and irregular asteroids/moons with nothing but craters seem to be really rare.

I get the impression that we may be looking at erosion features but I'm not sure how something like that might work.

Congratulations to the Cassini team for perfect pointing this time.

[machi]

Excellent images! Ski slopes on the Saturn's moon!
Surface of Helene is really extraordinary and it looks, that it is very young.

[charborob]

Here's a try at a cross-eyed 3D view:

[Phil Stooke]

It looks as if a surface crust is eroding away... very odd.

Phil

[Ian R]

Here's a 'bouncy' flyby movie:

http://youtu.be/HiHSM-_fes4?hd=1

[Juramike]

Here's a 'bouncy' flyby movie:

Wow. When the thin crescent slowly reveals itself to be an object coming out of the gloom....wow.

That is beautiful.

[ElkGroveDan]

Great work Ian. I know how time consuming that can be.

Is that series cycling through images taken with different filters?

[Phil Stooke]

Great work, everyone.

Phil

[ugordan]

It looks as if a surface crust is eroding away... very odd.

Calypso also appears to have surface features resembling this. The resolution there is low, but we didn't notice these on Helene in lower resolution imagery, either.

[Juramike]

To me, it looks like ring material is coating up and loading onto the surface. Then at some point, it releases and makes an avalanche that fills into the basin.

Trying to get a sense of scale, this is about the size of a big avalanche chute on Earth, but I imagine the whole motion being much gentler due to the really low gravity.

[ugordan]

To me, it looks like ring material is coating up and loading onto the surface.

Looking at Ian's atlas, it does seem to be the case that the leading hemisphere is smooth, while the trailing is heavily cratered. My guess would be small impacts over time causing quakes to shake material down slope.

I wonder if the trailing hemisphere is spectrally redder as a consequence.

[cbcnasa]

Amazing image and interesting craters and errosion of the surface.

[jasedm]

Awesome with a capital 'awe'

I've been looking forward to this flyby for a couple of months. I get home from work hoping to browse the raw images; and come here first to find that not only was the camera pointing inch-perfect, but the raw images have been enhanced and stacked, there's a cross-eye stereo view to enjoy, and even a flyby movie on 'You tube'

Phenomenal work everybody!!

I'm sure there's a little detail to be teased out courtesy of saturnshine too.....

[Poolio]

Incredible. Thanks again and again to the Cassini team and all of the image mavens here for providing the rest of us with a seemingly endless chain of such awe inspiring moments. Longest day of the year (almost), and I have a sudden yearning for winter.

[brellis]

Looks kinda like a used painting sponge:

Attached image(s)

 

[Phil Stooke]

No, that's Hyperion!

Phil

[Gsnorgathon]

I'd love a hi-res enough view to do a good comparison of Helene's flow features with Martian gullies.

[belleraphon1]

Thanks CASSINI and UMSF image mages....

Agree with Juramike and ugordan. Think this is some ring particle loading phenomenon.

Whatever.... man... is she beautiful!!!!

Craig

[Stu]

Good... ***grief***...

Just got back from a day in Blackpool (bought some rock, ate some ice cream, met some daleks, as you do) and went online to see what I've missed -

Look at THAT!!!

I'll say it too: great work everyone who worked on these images. Just brilliant processing and "citizen science" (hate that term but it seems to have stuck... oh well...)

See, DAWN team? See what happens when you release your images quickly and generously? People like those here treat them with care and admiration and use them to create works of art and wonder, which get other people buzzing like bees on crack about your mission! Stop ****ing about and let those pictures fly free!!

[nprev]

Stu: Well said!!!!!!!!!!!!!!!!!!!!!!!!

Helene: !!! GREAT work, everyone!

After seeing this, I'm beginning to wonder if Cassini herself might glaze over in a few years!

[Astro0]

I'm just blown away by the subtlety of the light in this image - the first frame in Cassini's Helene sequence - image N00172780.

Does anyone know if the light shining at the bottom of the frame is Saturn's limb/terminator, a moon or some other feature? Is the planet part of the background?

Also, with an eXtreme contrast stretch (right), Helene's body comes out of the darkness



BTW, nice job everyone of the images produced so far.
Cassini's own image release is here and the same from JPL here.

[djellison]

Does anyone know if the light shining at the bottom of the frame is Saturn's limb/terminator, a moon or some other feature? Is the planet part of the background?

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.

[Juramike]

I wonder if the color changes on the surface are a grain-size phenomenon? Fine coating --> lumpy bigger grained avalanche debris
or grains on the surface slowly subliming-redepositing to get bigger grains, then getting ground down to dust during the avalanche event? (initial Fine coating --> bigger recrystallized grains --> avalanche dust). Hyperion also has the same kinda look.

Anyone know if VIMS also got images?

[ugordan]

Anyone know if VIMS also got images?

Even if it did, the pixels would be so large you would have trouble landing one on just the darker or bright stuff.

[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]

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:

[Phil Stooke]

Very nice. I think that other face is the leading side as you say.

Phil

[wildespace]

Just "discovered" Helene, what a peculiar-looking moon! Any idea what its surface gravity would be?

Here's my RGB composite from N00172891, N00172892, and N001728913




Enhanced saturation:


A lot of work went into "massaging" the individual images into alignment, but there's still some colour fringing.

[Explorer1]

007 m/s² from Wolfram Alpha: http://www.wolframalpha.com/input/?i=helene+surface+gravity
The equation is pretty simple to calculate oneself, though: g = G * M / r².