Cassini and Saturn's moons - Page 17

ToSeek · #**481** (**permalink**) 07-August-2006, 05:36 PM

Spacemad · #**482** (**permalink**) 07-August-2006, 07:46 PM

This false colour image of Hyperion is really great. I saw it earlier today in a newsletter I'm subscribed to.

I'm always greatly interested in seeing images of the objects that populate our universe.

I really love the images that we get from the Hubble Space Telescope as well as from Cassini. I´ve collected 100s of images from the different probes that are exploring the Solar System.

BigDon · #**483** (**permalink**) 08-August-2006, 05:43 AM

Now isn't Hyperion a conglomeration of smaller iceballs that doesn't have the mass to become spherical and solid? Hence all the caverns and pockmarks and such?

ToSeek · #**484** (**permalink**) 08-August-2006, 03:29 PM

Wikipedia has this to say about Hyperion's composition:

Quote:

Like most of Saturn's moons, Hyperion's low density indicates that it is composed largely of water ice with only a small amount of rock. It is thought that Hyperion may be similar to a loosely accreted pile of rubble in its physical composition. However, unlike most of Saturn's moons, Hyperion has a low albedo (0.2–0.3), indicating that it is covered by at least a thin layer of dark material. This may be material from Phoebe (which is much darker) that got past Iapetus. Hyperion is redder than Phoebe and closely matches the color of the dark material on Iapetus.

The "rubble pile" composition is believed to be the case for many asteroids, comets, and captured moons.

Jerry · #**485** (**permalink**) 09-August-2006, 09:53 PM

Interesting. There was one blurb on the Cyclops site that indicated that the red stuff on Phoebo is made up of iron-rich compositions, but most of the time, it is just called red stuff.

ToSeek · #**486** (**permalink**) 11-August-2006, 03:58 PM

True-color image of Hyperion

Blob · #**487** (**permalink**) 13-August-2006, 12:37 PM

This mage of Titan was taken by the Cassini spaceprobe on August 10, 2006, when it was approximately 3,093,156 kilometres away.

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The image was taken using the CL1 and CB2 filters.

Credit NASA/JPL

Blob · #**488** (**permalink**) 18-August-2006, 03:03 PM

This Cassini flyby image shows Titan's dark mid-latitudes, and the southern terrain.
This was the first in a series of "illuminated outbound flybys" of where the illuminated hemisphere was visible following the closest approach. Cassini's flyby of Titan on July 22, 2006 sent the spacecraft into a more inclined orbit about Saturn.

The image was taken in polarised infrared light with the Cassini spacecraft wide-angle camera on July 22, 2006 at a distance of approximately 148,000 kilometres from Titan. Image scale is 9 kilometres per pixel.

Credit NASA/JPL

Blob · #**489** (**permalink**) 20-August-2006, 01:23 PM

This image of Helene was taken on August 17, 2006 by the Cassini spaceprobe when it was approximately 50,587 kilometres away.

The image was taken using the CL1 and CL2 filters.

Credit NASA/JPL

Blob · #**490** (**permalink**) 20-August-2006, 01:27 PM

This image of Rhea was taken be the Cassini space probe on August 17, 2006, when it was approximately 190,367 kilometres away.

The image was taken using the CL1 and UV3 filters.

Credit NASA/JPL

Superluminal · #**491** (**permalink**) 20-August-2006, 07:13 PM

Look on the bottom left about a quarter of the way up. (The Helene image.) Is a tiny speck. Any idea what it is? To my eyes it looks slightly elongated so probably not a back ground star.

01101001 · #**492** (**permalink**) 20-August-2006, 08:06 PM

Quote:

Originally Posted by Superluminal

Look on the bottom left about a quarter of the way up. (The Helene image.) Is a tiny speck. Any idea what it is? To my eyes it looks slightly elongated so probably not a back ground star.

NASA: Cassini-Huygens Frequently Asked Questions - Raw Images

Quote:

What are those streaks I see in some images?

There are high-energy particles that fly though space called cosmic rays. When one of these particles hit the camera's sensor, it causes a bright spot. When one of the particles hit the camera's sensor edge-on, it can leave a trail across the image. Exposures shorter than a second will not have many of these spots or trails. However, long exposures, like those from a minute to 20 minutes will contain many of these trails.
[...]
Why don't I see stars in the images?

The exposures needed to take images of Saturn and its moons are still fairly short compared with the exposure times it takes to see stars. If you look really close you can sometimes see stars in images that are overexposed.

Cugel · #**493** (**permalink**) 20-August-2006, 08:09 PM

If you enhance that speck it turns out to have some dark gray pixels surrounding it, so I think it is actually another small moon. Possibly Polydeuces that is in the same orbit as Helene.

Superluminal · #**494** (**permalink**) 20-August-2006, 10:07 PM

I'm familiar with gamma ray strikes, but this looks like there is something there.
Polydeuces and Helene, one is 60 deg. ahead and the other is 60 deg. behind Deone, so not likely Polydeuces.

Cugel · #**495** (**permalink**) 20-August-2006, 11:12 PM

Quote:

Originally Posted by Superluminal

I'm familiar with gamma ray strikes, but this looks like there is something there.
Polydeuces and Helene, one is 60 deg. ahead and the other is 60 deg. behind Deone, so not likely Polydeuces.

Yes, you're right. It's not Polydeuces and not Dione.
If it turns out to be an undiscovered moon we should call it LittleSpeck.

Wolverine · #**496** (**permalink**) 29-August-2006, 07:02 PM

A lovely new peek at Tethys has been posted today.

Toward Melanthius

Blob · #**497** (**permalink**) 01-September-2006, 12:33 AM

This image shows Dione's tortured complex of bright cliffs. At lower right is the feature called Cassandra, exhibiting linear rays extending in multiple directions.
The trailing hemisphere of Dione (1,126 kilometres across) is seen here. North is up.

The image was taken in polarised green light with the Cassini spacecraft narrow-angle camera on July 24, 2006 at a distance of approximately 263,000 kilometres from Dione. Image scale is 2 kilometres per pixel.

Source

Blob · #**498** (**permalink**) 01-September-2006, 02:39 AM

MISSION DESCRIPTION

Nearly 47 days after Titan-16, Cassini returns to Titan for its eighteenth targeted encounter.
The closest approach to Titan occurs on Saturday, September 7, at 20:16 spacecraft time (September 7 at 2:16 p.m. Pacific Time) at an altitude of 1000 kilometres above the surface and at a speed of 6.0 kilometres per second. The latitude at closest approach is 23° N (near equator), and the encounter occurs on orbit number 28.
This encounter is set up with two manoeuvres: an apoapsis manoeuvre on August 1, and an approach manoeuvre, scheduled for September 4. This inbound encounter occurs about 2 days before Saturn closest approach.

Read more (1mb, PDF)

Wolverine · #**499** (**permalink**) 01-September-2006, 10:32 PM

Marvelous shot of Dione.