Cassini Equinox & Solstice Mission, (nine year extension)!!.

[3488]

Thank you very much EarthlingX. Fascinating stuff.

What is very apparent as you say is that Tethys appears far brighter than Dione. However a surface that has seen geological activity of which Dione has seen plenty of IMO would be brighter as it would have had less time to accumulate a darkening dusty layer & darken due to the weak UV radiation from the Sun at that distance.

Here is an oxymoron. Tethys appears far more primitive than Dione, peppered with craters & has the Ithaca Chasmata, which can be explained as a fracture in the more brittle ice crust of Tethys ruptured when the slushy interior froze.

Dione appears to be the most internally differentiated of Saturn's moons, even more so than Titan which is a huge surprise (Titan under the icy crust appears to be more like Jupiter's moon Callisto, an undifferentiated ball of rock & ice, also more like Rhea too).

Tethys on the other hand apears to be a giant undifferentiated ball of ice with perhaps a small amount of rocky material. Tethys does have a 'smoother' band around the equator with slightly smaller craters, but this too is ancient. Dione has crumple zones, thrust faulting, possible cryovolcanic resurfacing in a few places, certainly appears more evolved than Tethys.

Fascinating stuff.

Andrew Brown.

 

[3488]

Cassini searches for Kronian Aurora Australis. The bulk of Saturn can been in the top part with the limb sweeping below centre with trailed stars. Hot pixels can be seen in front of the night side of the far south of Saturn. The stars are in Aquila to the west of Altair / Alpha Aquilae.

Andrew Brown.

 

[EarthlingX]

Thanks Andrew for that thoughts about Tethys and Dione, just one thing : i'm only quoting what is on Ciclops, it will be ages before i will know enough to write such a comment, if ever, more likely never
To me, that image is just cute, lovely, awesome and aahh ... :shock: ...

As Carolyn Porco recently wrote :

Imagine being in a spaceship, flying over Saturn's moon Dione. May happen some day. http://bit.ly/akmlTj

Perhaps even while some of us are still around ? I certainly wish so ..
(EarthlingX slaps his face a couple of times with a big trout : "Wake up, silly !")

What are those streaks in the last images you posted ?

Oh, and this is coming soon :

saturn.jpl.nasa.gov : Titan Flyby (T-71) - July 7, 2010

T-71: Here Comes the Sun


The Cassini spacecraft looks toward the dark Senkyo region on Saturn's moon Titan. This image was taken April 8, 2010.

During this Titan flyby, the ion and neutral mass spectrometer (INMS) looks at the effect of rising solar activity in southern latitudes, with closest approach on the dayside near the terminator. RADAR has a southwestern quadrant ride-along synthetic aperture radar (SAR) of a poorly covered region in the prime and extended mission, valuable for determining Titan's global shap via SAR topographic measurements. CIRS and ISS monitor Titan clouds and the evolution thereof during the day after closest approach, a so-called "caboose" period.

 

[3488]

Hi EarthlingX,

I assume you mean the streaks in the bottom half of the images above? They are trailed stars, as Cassini had to take long exopures to capture any aurorae above Saturn's night side.

9 KM long Daphnis is seen here along with the rippling in the Keeler Gap in the rings.

2 clickable thumbnails to full sized frames.


2 enlarged sharpened crops of 9 KM long Daphnis. There appears to be a 2 KM wide crater on Daphnis.

Andrew Brown.

 

[EarthlingX]

Little moon making waves

I assume you mean the streaks in the bottom half of the images above? They are trailed stars, as Cassini had to take long exopures to capture any aurorae above Saturn's night side.

What are then those static dots ? If they are artefacts, then they are pretty easy to filter out, for all images taken by this instrument, and i might just try that. It would be a bit silly, if those are stars though ..

 

[nimbus]

Another curious thing is how Saturn's limb is darker than open space on the right side of the picture.

 

[3488]

Hi EarthlingX.

Yes all of the dots are instrument noise & Cosmic Ray strikes.

Hi nimbus,

That is strange, I wonder if it is the way the CCD captures light from the portion of the frame that is starlit????? I also looked to see if there was any lightning in Saturn's atmosphere from these & could not identify any.

Also I can see that Daphnis appears to have a 'large' crater, approx 2 KM wide on a 9 KM long body. Wonder if this shows that Daphnis is an icy rubble pile held together by gravity (a more solid body would shatter)???

Andrew Brown.

 

[EarthlingX]

SDC : Giant Propellers Discovered In Saturn's Rings

By Denise Chow
SPACE.com Staff Writer
posted: 08 July 2010
03:43 pm ET



Giant propeller-shaped structures have been discovered in the rings of Saturn and appear to be created by a new class of hidden moons, NASA announced Thursday.

NASA's Cassini spacecraft spotted the distinctive structures inside some of Saturn's rings, marking the first time scientists have managed to track the orbits of individual objects from within a debris disk like the one that makes up Saturn's complicated ring system.

"Observing the motions of these disk-embedded objects provides a rare opportunity to gauge how the planets grew from, and interacted with, the disk of material surrounding the early sun," said the study's co-author Carolyn Porco, one of the lead researchers on the Cassini imaging team based at the Space Science Institute in Boulder, Colo. "It allows us a glimpse into how the solar system ended up looking the way it does."

Photos of the propellers taken by Cassini show them to be huge structures several thousands of miles long. By understanding how they form, astronomers hope to glean insight into the debris disks around other stars as well, researchers said.

 

[3488]

Just to say I am still really struggling but am a little better today, but still not up to deep discussion as yet, but still want to contribute to the Community. Had to re-edit this as my spelling is atrocious today, just being a ****** as normal.

Titan Ontario Lacus seen by Synthetic Aperture Radar.

Clickable Thumbnail to full size image.


Synthetic Radar Aperture Image superimposed a normal IR ISS image. Thr Red Cross marks Titan's South Pole.

Animations of flyover overs of Lacus Ontario on Titan.

Andrew Brown.

 

[3488]

NGC 5139 / Omega Centauri seen through the Keeler Gap in the rings of Saturn. Sunday 29th March 2009.

Movie here.

Andrew Brown.

 

[EarthlingX]

NGC 5139 / Omega Centauri seen through the Keeler Gap in the rings of Saturn. Sunday 29th March 2009.

Movie here.

Andrew Brown.

 

[EarthlingX]

http://www.jpl.nasa.gov : Blowing in the Wind: Cassini Helps with Dune Whodunit

July 29, 2010


Cassini radar sees sand dunes on Saturn's giant moon Titan (upper photo) that are sculpted like Namibian sand dunes on Earth (lower photo). The bright features in the upper radar photo are not clouds but topographic features among the dunes. Image credit: NASA/JPL (upper photo); NASA/JSC (lower photo)

The answer to the mystery of dune patterns on Saturn's moon Titan did turn out to be blowing in the wind. It just wasn't from the direction many scientists expected.

Basic principles describing the rotation of planetary atmospheres and data from the European Space Agency's Huygens probe led to circulation models that showed surface winds streaming generally east-to-west around Titan's equatorial belt. But when NASA's Cassini spacecraft obtained the first images of dunes on Titan in 2005, the dunes' orientation suggested the sands – and therefore the winds – were moving from the opposite direction, or west to east.

A new paper by Tetsuya Tokano in press with the journal Aeolian Research seeks to explain the paradox. It explains that seasonal changes appear to reverse wind patterns on Titan for a short period. These gusts, which occur intermittently for perhaps two years, sweep west to east and are so strong they do a better job of transporting sand than the usual east-to-west surface winds. Those east-to-west winds do not appear to gather enough strength to move significant amounts of sand.

A related perspective article about Tokano's work by Cassini radar scientist Ralph Lorenz, the lead author on a 2009 paper mapping the dunes, appears in this week's issue of the journal Science.

 

[EarthlingX]

http://www.ciclops.org : The Mimas Atlas

Presented here is a complete set of cartographic map sheets from a high-resolution atlas of Saturn's moon Mimas. The atlas is a product of the imaging team working with NASA's Cassini spacecraft.

Mimas, as imaged by NASA's Voyager spacecraft in the early 1980s, has a very large, distinguishing crater that makes it look like the "Death Star." As shown in this map, that crater is named Herschel.

The map sheets form a three-quadrangle series covering the entire surface of Mimas at a nominal scale of 1:1,500,000. The map data were acquired by the Cassini imaging cameras. The mean radius of Mimas used for projection of the maps is 198.2 kilometers (123.2 miles). Image scale is 216.2 meters per pixel. The resolution of the map is 16 pixels per degree.

Thumbs :

saturn.jpl.nasa.gov : The Mimas Atlas

July 28, 2010

saturn.jpl.nasa.gov : The Mimas Atlas -- Accolon

July 28, 2010

saturn.jpl.nasa.gov : The Mimas Atlas -- Arthur

July 28, 2010

saturn.jpl.nasa.gov : The Mimas Atlas -- Herschel

July 28, 2010

 

[3488]

Thank You very much EarthlingX. You beat me to it, I was going to post something up about these excellent maps of Mimas.

What I have done is copied & pasted your excellent post over onto the Mimas thread I started a while back on SS&A as it also belongs there in the context of Mimas as a body in it's own right.

Brilliant mate, I thank you very much.

I have downloaded & saved all of the maps in my growing collection of planetary images & maps. I have not been very well at all recently & this sort of thing, like the Rosetta Asteroid 21 Lutetia encounter, Mercury MESSENGER , MERS, etc help me to realise that things are not as bad as they seem, as wel las my friends on here.

What appears to be apparent to me is that there appears to be no antipodal disturbances to Herschel Crater, much like opposite the Valhalla Basin on the Jupiter moon Callisto, but unlike opposite the Caloris Basin on Mercury (where there is hilly terrain antipodal to Caloris Basin). Mimas other than Herschel Crater & impact melt from thereof appears fairly uniformly cratered, I cannot see any evidence unlike Enceladus or Dione that Mimas has rolled.

As maybe expected Herschel Crater is on the equator on the leading hemisphere as Mimas orbits Saturn, so it was a head on impact (Wayne will know more than me on this, but this is my own opinion).

Also these maps show that Mimas is now well mapped with the exception of a tiny area near the north pole, that may be filled in during the Solstice Mission. Not all of Mimas has been seen at the same resolution, but certainly enough has been to show us clearly cratering densities, general morphology & geological processes or lack thereof in the case of Mimas.

Andrew Brown.

 

[EarthlingX]

You alerted me about these maps Nice to see you doing better

What would no antipodal disturbance tell us about Mimas ? Hard interior ?

 

[3488]

On Tuesday 27th July 2010, Cassini observed Dione pass across the north polar region of Rhea.

Dione was 1.11 million KM & Rhea was 1.59 million KM from Cassini, so despite Rhea @ 1,528 kilometres wide being considerably larger than Dione @ 1,123 kilometres, they both appeared the same size.

Antenor Crater on Dione is very obvious with the peak as is the fact Rhea is far more heavily createred than Dione, despite their distance.

Andrew Brown.

 

[3488]

Cassini carried out one close pass of Enceladus & medium passes of Tethys & Dione.

Clickable thumbnails to full sized images.

Tethys northern polar region & Penelope Crater.


Dione.


Enceladus in front of Saturn.


Enceladus above Saturn.


Enceladus plumes.


Enceladus from 4,700 KM. Ice boulders are visible.


Enceladus, looking down into an active vent from 2,700 KM.


Andrew Brown.

 

[MeteorWayne]

You alerted me about these maps Nice to see you doing better

What would no antipodal disturbance tell us about Mimas ? Hard interior ?

More likely the opposite, too "fluffy" to transmit the force to the other side.

 

[EarthlingX]

saturn.jpl.nasa.gov : CHARM

Cassini Project Science Office Presents:
CHARM: Cassini-Huygens Analysis and Results from the Mission

A lot of very nice reading and pictures

 

[3488]

It is indeed EarthlingX.

There is a lot of great stuff in the CHARM release.

Mimas as seen from 1.5 million KM on: Tuesday 31st August 2010. The Herschel Crater can be seen in the sunlit crescent. The faintly Saturnlit night side can be seen. The oblateness of Mimas is clearly visible.

I sharpened enlarged the crop three times & cropped it out of the original frame. Then rotated it 90 degrees clockwise.

Herschel Crater was on the sunset terminator & 19:15 HRS UTC on: Tuesday 31st August 2010.

Andrew Brown.

 

[EarthlingX]

The equatorial ridge - Valterne Mons, Iapetus
[youtube]http://www.youtube.com/watch?v=o6J69uqPVGY[/youtube]

galsat400 | September 03, 2010

Perspective rendering of one of the highest parts of the amazing equatorial ridge on Iapetus. The ridge, 20 kilometers wide, stands roughly 18 kilometers high in this region. Despite the length, there are several gaps in the ridge. The origin of the ridge remains unknown but is still one of the most spectacular edifices in the Solar System..

 

[3488]

Hi EarthlingX,

Also copied your post over to the Iapetus thread in SS&A. Great stuff, thank you so much for bringing it here. :mrgreen:

You may like this too?? :?: :?: :?:

[youtube]http://www.youtube.com/watch?v=baaGOqIJaFM[/youtube]

Andrew Brown.

 

[3488]

Literally just in, Dione from close pass earlier TODAY. I have just been e-mailed these from CICLOPS. These ARE NOT even on the NASA / JPL Cassini RAW Images site yet. As of 15:55 UTC on: Saturday 4th September 2010.

SDC may be one of the very first to have these. All clickable thumbnails. I have done nothing with them. Posted as I got them.

Dione during approach from a far northern perspective, never seen from this angle before.




Tectonic canyons in the far north of Dione. Looks a lot like the Uranus moon Ariel as seen by Voyager 2.


Crescent north polar Dione. Some features are faintly lit by Saturn on the right on the night side.


Dione north polar region.


IIRC correctly this shot includes th actual North Pole of Dione. Never before seen at this level of detail.


Andrew Brown.

 

[EarthlingX]

Hi EarthlingX,

Also copied your post over to the Iapetus thread in SS&A. Great stuff, thank you so much for bringing it here. :mrgreen:

You are very much welcome, they are well worth more attention

I recently read Emily Lakdawalla's article about this videos :
http://www.planetary.org : Fly over Saturn's icy moons

You may like this too?? :?: :?: :?:

http://www.youtube.com/watch?v=baaGOqIJaFM

Andrew Brown.

Sure do

This are mostly raw images ?

Crosspost
Very nice images, thanks

 

[3488]

Hi EarthlingX, yes they are raw images. I have sorted them into some sort of order & made them available to SDC.

A few more 1,123 KM wide Saturn moon Dione images from the pass on Saturday 4th September 2010.

I will work on some of these tomorrow when I am not so tired, but thought I would post these up.







Andrew Brown.