Cassini/Huygens Mission Update Thread Pt. 2

[scottb50]

Where did you hear this? <div class="Discussion_UserSignature"> </div>

 

[alpha_taur1]

I think it should be called Shiela, or Gertrude. <img src="/images/icons/smile.gif" />

 

[yurkin]

<font color="yellow">One theory, originally proposed by Édouard Roche in the 19th century, is that the rings were once a moon of Saturn whose orbit decayed until it came close enough to be ripped apart by tidal forces (see Roche limit). A variation of this theory is that the moon disintegrated after being struck by a large comet or asteroid.</font><br />http://en.wikipedia.org/wiki/Saturn_(planet)<br />also<br />http://space.about.com/od/cassinimissionnews/a/cassini070804a.htm<br /><br />It is currently the most widely accepted theory. I was really something more Greek, isn’t there a Greek god of destruction or something like that.<br />

 

[Leovinus]

<i>Cassini was nearly in the plane of Saturn's rings when it took this image of Janus. The nearly edge-on rings appear almost ribbon-like in this view, and some surface detail is visible on the small moon. Janus is 181 kilometers (113 miles) across.<br /><br />The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 18, 2005, at a distance of approximately 911,000 kilometers (566,000 miles) from Janus and at a Sun-Janus-spacecraft, or phase, angle of 101 degrees. The image scale is 5 kilometers (3 miles) per pixel. </i> <div class="Discussion_UserSignature"> </div>

 

[vogon13]

I have been trying to imagine 'easy' ways of getting additional flybys of Iapetus during the Cassini extended mission phase (if we are lucky enough to get one). The near 5:1 commensurability between the orbital periods of Titan and Iapetus suggests a 'trick' that may be under consideration at JPL. Imagine Cassini on an orbit around Saturn with a period of ~40 days. If started (phased is the word I want to use but not sure it would mean to others what I intend) at the proper time, and Cassini was properly inclined in its path around Saturn, every other orbit would bring you fairly close to Iapetus for quite a period of time. The encounters would have similar geometries to each other, but if the period of the orbit was exactly 2.5 X Titans period, Iapetus would slowly 'drift' thru the repeating 'petal' of Cassinis orbit. Encounters could be 'tweaked' to be north polar, equatorial, or south polar. Suspect in bound and out bound 'leg' of each petal may also provide interesting (complimentary) encounter trajectories.<br /><br />Another advantage of the this orbit (I think) is that once set up, fuel use would be very low to maintain. <br /><br />A potential disadvantage is what is there for Cassini to do during the ~80 days between Iapetus encounters? Long term Saturn observations? Would other satellites cooperate and be favorably placed for closer encounters? Would Titan passes repeat previous geometries, thereby making this scenario less desirable, or, conversely, if there is something interesting and variable we want to watch (like persistent storms or geysers, etc.) maybe this makes it more of something we want to do?<br /><br />A constraint would be to set this up so the portion of Iapetus you want to look at is sunlit. Having similar geometries on subsequent encounters would enable radar and visual scans of the same locales. This may be important for a follow on Iapetus rover mission, if we can determine suitability of surface for rover operations. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[alokmohan]

Dont forget hoopla of hyperion.

 

[vogon13]

Good point! Set this up at right time and you would get a Hyperion encounter every orbit.<br /><br /> Cooool! <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[odysseus145]

Here's a awesome picture of Titan with Saturn's rings in the background. <div class="Discussion_UserSignature"> </div>

 

[Leovinus]

<i>Although the Huygens probe has now pierced the murky skies of Titan and landed on its surface, much of the moon remains for the Cassini spacecraft to explore. Titan continues to present exciting puzzles.<br /><br />This view of Titan uncovers new territory not previously seen at this resolution by Cassini's cameras. The view is a composite of four nearly identical wide-angle camera images, all taken using a filter sensitive to wavelengths of infrared light centered at 939 nanometers. The individual images have been combined and contrast-enhanced in such a way as to sharpen surface features and enhance overall brightness variations.<br /><br />Some of the territory in this view was covered by observations made by the Cassini synthetic aperture radar in October 2004 and February 2005. At large scales, there are similarities between the views taken by the imaging science subsystem cameras and the radar results, but there also are differences.<br /><br />For example, the center of the floor of the approximately 80-kilometer-wide (50-mile) crater identified by the radar team in February (near the center in this image, see PIA07368 for the radar image) is relatively bright at 2.2 centimeters, the wavelength of the radar experiment, but dark in the near-infrared wavelengths used here by Cassini's optical cameras. This brightness difference is also apparent for some of the surrounding material and could indicate differences in surface composition or roughness.<br /><br />Such comparisons, as well as information from observations acquired by the visual and infrared mapping spectrometer at the same time as the optical camera observations, are important in trying to understand the nature of Titan's surface materials.<br /><br />The images for this composite view were taken with the Cassini spacecraft on March 31, 2005, at distances ranging from approximately 146,000 to 130,000 kilometers (91,000 to 81,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of about 57 de</i> <div class="Discussion_UserSignature"> </div>

 

[silylene old]

That's an amazing picture of Titan.<br /><br />Do I see a hint of a polar icecap? Or a hint of a polar fogbank? <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[vogon13]

You are probably discerning a difference in 'texture' in different regions. Keep in mind though, most of the Cassini pictures haven't been gridded with lat. and long. yet and due to some of the unexpected flyby angles, be cautious on where you think the poles and equator are.<br /><br />They (NASA) don't intend to make this harder, they are just super busy with the torrent of data coming in from Cassini. We are probably more attuned to the meager trickle we got from Galileo.<br /><br />Yeah, I'm still in a snit about that crappy (sorry Cali!) antenna on Galileo. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[Leovinus]

That picture is an assembly of many shots. The clear ones in center might be at a higher resolution than the polar ones giving the appearence of a polar fog or polar cap. It's hard to know unless you're the guy in JPL analyzing the pictures. <div class="Discussion_UserSignature"> </div>

 

[Leovinus]

<i>During a close flyby of Titan on March 31, 2005, Cassini's cameras got their best view to date of the region east of the bright Xanadu Regio. This mosaic consists of several frames taken by the narrow-angle camera (smaller frames) put together with an image taken by the wide-angle camera filling in the background. It reveals new detail of dark expanses and the surrounding brighter terrain.<br /><br />Some of the features seen here are reminiscent of those seen elsewhere on Titan, but the images also reveal new features, which Cassini scientists are working to understand.<br /><br />In the center of the image (and figure A at bottom) lies a bright area completely surrounded by darker material. The northern boundary of the bright "island" is relatively sharp and has a jagged profile, resembling the now-familiar boundary on the western side of Xanadu (see PIA06159). The profile of the southern boundary is similar. However, streamers of bright material extend southeastward into the dark terrain. At the eastern end of the bright "island" lies a region with complex interconnected dark and bright regions (see figure B).<br /><br />To the south, the bright terrain is cut by fairly straight dark lines. Their linearity and apparently angular intersections suggest a tectonic influence, similar to features in seen in the bright terrain west of Xanadu (see PIA06158).<br /><br />The camera's near-infrared observations cover ground that was also seen by Cassini's synthetic aperture radar in October 2004 and February 2005. Toward the northeastern edge of the dark material a dark, circular spot in the middle of a bright feature (see figure C) is an approximately 80-kilometer-wide (50-mile) crater identified in the February 2005 radar data (see PIA07368 for the radar image).<br /><br />The resolution of this new image is lower but sufficient to reveal important similarities and differences between the two observations. Part of the crater floor is quite dark compared to the surrounding mater</i> <div class="Discussion_UserSignature"> </div>

 

[jaredgalen]

I didn't realise cassini was having any problems at all.<br />This article seems to tell of quite a few<br />that don't sound in any way trivial.<br /><br />http://www.newscientist.com/article.ns?id=dn7246<br />

 

[douglas_clark]

Leo,<br /><br />Am I right in thinking that the Titan photo you posted doesn't look like a sphere? Is this just an artifact or not?<br /><br />douglas

 

[spacechump]

"The mosaic is centered on a region at 1 degree north latitude, 21 degree west longitude on Titan. The Cassini spacecraft narrow-angle camera images were taken using a filter sensitive to wavelengths of polarized infrared light and were acquired at distances ranging from approximately 148,300 to 112,800 kilometers (92,100 to 70,100 miles) from Titan. Resolution in the images is about 1 to 2 kilometers (0.6 to 1.2 miles) per pixel."<br /><br />That should explain it pretty well......but long story short its just showing a small section of Titan. Not the whole moon. <br /><br />Edit: Lol...maybe I should ask first....what image are you talking about?! My bad!

 

[volcanopele2]

If you are talking about the mosaic, I had to crop off the top fifth of the background wide angle image. I divide the methane window image (CB3) with an image that shows the lower atmosphere (MT1 for the smaller images, RED for the wide angle image) to produce an image with better contrast. Unfortunately, the edge of the frame clipped the top of the wide angle red filter image (http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=35962)<br />After that, I map projected the ratio image (CB3/RED), and cropped around the narrow angle images.

 

[volcanopele2]

T5 is coming up awfully quickly after T4. This 1025 km flyby will take place on Saturday. For further info:<br /><br />My T5 post on my blog - http://volcanopele.blogspot.com/2005/04/titan-5-flyby-info.html<br /><br />JPL's T5 Mission description - http://saturn.jpl.nasa.gov/multimedia/products/pdfs/t5Flyby20050412a.pdf

 

[fangsheath]

I'm surprised no one else seems to have done this, I thought it would be helpful in trying to understand the landscapes on Titan. I have rather carefully overlain the near-infrared image of this crater with the radar image, matching up recognizable features, so that we can clearly see the two at the same scale for direct comparison. Things may not match up perfectly due to projection effects but I think it is sufficient for my purpose. One of the things I notice is that areas that seem rather uniform on the radar image are anyting but in IR. Conversely, areas that seem uniformly dark on the IR image sometimes have wildly divergent radar reflectivities. I think the latter can be explained by the hypothesis that there is a coating of dark organics that has accumulated in the lower spots over underlying topography that is rather variable. The former may be the result of cryovolcanism. I cannot shake the impression that this planetoid is being quite actively shaped by extrusions and and flows of material, a landscape that is, to varying degrees, somewhere in a state between liquid and solid.

 

[thechemist]

Somebody find this guy a place to post his pictures directly !! <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>

 

[thechemist]

The guardians of the F-ring <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>

 

[telfrow]

http://www.spaceref.com/news/viewsr.html?pid=16166<br />Full-Res: PIA06225 <br />NASA Cassini Image: Saturn Seen Through Titan's Clouds <br /><br /><i>Less than 20 minutes after Cassini's close approach to Titan on March 31, 2005, its cameras captured this view of Saturn through Titan's upper atmosphere. The northern part of Saturn's disk can be seen at the upper left; dark horizontal lines are shadows cast upon Saturn by its rings. Below this level, Titan's atmosphere is thick enough to obscure Saturn. <br />The diffuse bright regions of the image (below Saturn and at the right) are light being scattered by haze in the upper reaches of Titan's atmosphere. <br />This image is scientifically useful because it shows properties both of how Titan's haze transmits light (from the attenuation of light from Saturn) and of how the haze reflects light (from its brightness next to Saturn). <br />The image was taken in visible light with the Cassini spacecraft wide-angle camera at a distance of 7,980 kilometers (4,960 miles) from Titan, when Saturn was about 1.3 million kilometers (808,000 miles) away. Image scale is about 320 meters (1,050 feet) per pixel on Titan. </i><br /> <div class="Discussion_UserSignature"> <strong><font color="#3366ff">Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild.</font> - <font color="#3366ff"><em>Tennyson</em></font></strong> </div>

 

[centsworth_II]

<font color="yellow">"Yes."</font><br /><br />That should be: "Yes!" <div class="Discussion_UserSignature"> </div>

 

[volcanopele2]

We'll be looking in the same region as during the last flyby, but with much higher resolution images. The dwell times and exposures times for each footprint and image respectively have been increased to maximize signal to noise so hopefully we can get better quality high resolution images than during the first three encounters.

 

[titanian]

A view of Saturn from the surface of Titan:<br /><br />www.titanexploration.com