Saturday, February 05, 2005

Huygens Stereo Pairs

The Huygens DISR team has released five stereo pairs to show topography in the Huygens landing site region. The pairs showing the shoreline and "landing strip" region are particular impressive, with several broad plateaus "onshore".

Here are some links with commentary:

  • StereoA: This view shows the drainage channel region just "onshore" in the northern bright island. The major topographic features in this image are the two plateaus in the center and lower left of each image. The drainage basin onshore appear to lie in a topographic low, with the channels running toward the top of the image to a delta (see StereoD). One of the channels even appears to run along the side of the upper plateau.

  • StereoB: This view shows the eroded bright feature within the dark strait known as the "bird foot". To me, it looks like this region is pretty flat.

  • StereoC: This view shows an area a few miles from the landing site within the dark terrain. Here a dark flat plain is surrounded by elevated eroded bright terrain.

  • StereoD: This view shows a view similar to StereoA, though this view covers more of this particular drainage area, including the outlet. One of the key topographic feature is a tear-shaped plateau with two channels running toward the top of the frames. This view also shows that except for those two tributaries, most of the arroyos seem to be centered within a topographic valley (no surprise there).

  • StereoE: This view shows the "landing strip" and an apparent exposed cryomagma dike. I'll need to look at this one a little more to see if the landing strip resembles the Europan or Tritonian double-ridge topographically as I suspect.

Friday, February 04, 2005


I've added a tagboard to the sidepanel of my blog. So feel free to post to your hearts content. I've seen a number of websites have one of these and I think it can be useful. just provides another means of discussion.

By the way, for those posting in the comments, if you can provide some means of identification in your posts, that would be great. I'm not asking for your name and number, but if you come from #space or the MER Forums, if you append your posts with your handle, that would be fine. People not currently signed up on always come up as anonymous and as it stands it makes it very difficult to know who made a comment without something. I don't think I should force people to sign up for to comment if they don't want to just to know who made a comment, so I feel this is a reasonable solution.

Also, I have decided to go with "Titan Today" as the permanent name for my blog. Thanks to those who provided feedback on this matter.

Cassini Significant Events 01/27/05 - 02/02/05

The Significant events report for this past week is now up. Cassini is currently in the lull between encounters but it is still taking data.

Io Mountain Database

Sifting through the LPSC abstracts, I found one describing an online Io Mountain database. Quite easy to use and they even have quite a bit of data on my favorite Ionian mountain (next to my favorite Ionian volcano), but they still don't have the official name for it.

Rhea in Natural Color

CICLOPS released a true color version of Rhea to go with the clear filter view released a few days ago. As you can see, Rhea is not very colorful in natural color and only looks slightly different from the clear filter view. As seen during the Iapetus encounter, using a wider spread of filters, like IR3-GRN-UV3 produces a more useful false color image. But seeing what Rhea would look like some what like the human is useful.

Thursday, February 03, 2005

More on LPSC Abstracts Part 2

On the liquid hydrocarbons front, Titan's Elusive Lakes?: Properties and Context of Dark Spots in Cassini Ta RADAR Data by Lorenz et al. and Liquid Hydrocarbons on Titan's Surface? How Cassini ISS Observations Fit into the Story (so far) by Turtle et al. presents the results thus far on the subject from RADAR and ISS respectively. Lorenz et al. present 4 RADAR dark regions, with backscatter properties similar to asphalt, including one that appears similar to an oxbow lake in morphology. However, Lorenz et al. Stops short of saying whether these dark regions with the Ta RADAR swath are lakes or not but simply concludes that these dark features are most likely smooth hydrocarbon deposits. Turtle et al. discusses the current ISS evidence for and against liquid hydrocarbon deposits. Turtle et al. use specular reflection to search for bodies of liquid (since large regions of micron-scale smooth, non-liquid, terrain is unlikely but certainly possible). Through Tb, no such specular reflection has been seen.

Finally, Cassini VIMS Preliminary Exploration of Titan's Surface Hemispheric Albedo Dichotomy by Nelson et al. Looks at photometric properties of the bright and dark terrain as well as "circular" features at 2.02 microns. The authors reveal that the albedo of the bright terrain is 20% and the dark terrain, >5%. The bright terrain value is similar to the DISR value (12-20%) while the dark terrain is darker than the DISR value (10-12%).

More on LPSC Abstracts Part 1

Now that I have had a chance to scan through some of the Titan-related abstracts, I can make some comments on them.

Cryovolcanic Features on Titan's Surface as Revealed by the Cassini RADAR by Lopes et al. As I reported above, the Radar team is interepreting the bright-rimmed circular features as calderas, not craters, because of their irregular shapes and unidirectional flows. These features are discussed further in Impact Craters on Titan? Cassini RADAR View by Wood et al. The Lopes et al. abstract further discusses other cryovolcanic features including a 180 km wide pancake dome or shield with flows eminating from a central volcanic pit. Finally, several standalone cryovolcanic flow are discussed, including the large flow seen in a RADAR press release image. RADAR Reveals Titan Topography by Kirk et al. states that the bright margins of the flow likely represent a combination of topography and structural/compositional changes or the flow is 1000 meters tall (unlikely but would be similar to flow structures on Ariel).

The Kirk et al. abstract shows results of radarclinometry attempts to pull topographic information out of the Ta SAR data (the poster would presumably show results from T3 as well). Features seen in swath 3 at the eastern end of the Ta SAR data appear to be hills 5-10 km wide and 100-125 meters tall. The authors also discuss a flow eminating from a caldera that appears to be 200-300 meters tall. This would be consistent with the high-viscosity of water-ammonia cryolava (though these could always be Ionian-style flow fields).

VIMS Observations of Titan During the First Two Close Flybys by the Cassini-Huygens Mission by Rodriguez et al. and Deconvolution of Cassini VIMS Titan Cubes into Atmospheric Spectral Scattering, Surface Topographic, and Surface Spectroscopic Components by Soderblom et al. both discuss the highest resolution VIMS data. Rodriguez et al. interprets the "snail" feature in the highest resolution Ta image as a cryovolcanic dome, similar to the one seen by RADAR, albeit quite a bit smaller. This abstract also has a thumbnail of the unreleased Tb high-resolution data, showing a branching dark feature cutting into a featureless bright region. Soderblom et al. did some analysis of the Ta High-resolution data, including a photoclinometric analysis of a series of ridges and valleys south of the "snail". They suggest relief within this area of 600-800 meters, somewhat more than the RADAR results. The Soderblom et al. Abstract is significant for a having a false color view of the "snail".

Cassini Imaging Results at Titan by Mcewen et al. has a nice overview of ISS imaging of Titan as well as an updated map of Titan with Ta and Tb data included.

LPSC Abstracts

Abstracts for the Lunar and Planetary Sciences Conference are now online. The 36th LPSC will be held in Clear Lake, Texas between March 14 and 18. I will be in attendance presenting a poster. Below are some links to a few interesting abstracts. The sessions pertaining to Saturn's moons are Cassini at Saturn I, Cassini II, Cassini III, and Cassini at Saturn: Titan, Saturn, Rings, Icy Satellites.
More on the way. Needless to say I got a lot of reading to do tonight.

Titan: A World of Its Own has an article up as part of their SETI Thursdays series. The article makes some nice analogies (Titan is now weirder than Michael Jackson) but mainly focuses on the astrobiological potential of Titan. Of course, not being a fan of astrobiology, I think it's bunk for the reasons they list in the article (no surface liquid water for long time scales, too cold) but it is still an entertaining read.

Janus - January's moon

This is a newly released view of the small Saturnian satellite Janus, taken by Cassini last month. Cassini still hasn't bested Voyager's view of this satellite, but according to the Planetary Society, Cassini should get a great view of Janus in late April 2006.

Wednesday, February 02, 2005

Cassini Tour Schedule

Decepticon over at the MER Forum pointed out that the Planetary Society now has an updated Cassini tour schedule that includes the dates and distances of encounters with Saturn's moons for the entire mission. The page has been updated to include more "Voyager-class" encounters, like those of Mimas, Enceladus, and Rhea last month and more encounters with Saturn's smaller satellites like Calypso and Janus. Definitely a good resource to have.

Solar System Simulator updated

The Solar System Simulator, a website at JPL, has now been updated. The website allows visitors to simulate a view of a solar system body, like Titan, from another solar system body or spacecraft. A very cool tool that until recently didn't have the SPICE data to simulate the trajectory of Cassini after SOI last July 1.

Blog Name

Last week, I restarted this blog with a fresh new name, The Titanese Times. Yuriwho in the comments page suggested some other possible names:

The Titan Times
Titan Today
The Tides of Titan
The Winds of Titan
Whispers from Titan
The View from Titan

Personally, I would like to wait until we get some additional feature names, other than Xanadu. For a more permanent name, I would like something like Hotei Chronicle, Xanadu Today, or the Nun Sun (okay maybe not that last one). However, one thing going for something like Titan Today is that if people are searching for info on Titan or Titan news, they wouldn't search for Xanadu or Titanese, but for Titan. A name like Titan Today or The Titan Times might be a good bet.

JIMO pushed past 2015? reported yesterday that the Jupiter Icy Moons Orbiter (JIMO) maybe delayed past the current 2015 launch date thanks to decreased funding in the FY 2006 NASA budget. JIMO is to be the first mission in NASA's Project Prometheus, NASA's first attempt at Nuclear Electric Propulsion and is designed to orbit Europa, Ganymede, and Callisto.

While I am no Europa fan, I was hopeful in this mission, since with the wide power margin, a very powerful camera system could be placed on JIMO. With that system, even though the spacecraft was designed to explore the icy Galilean satellites, plenty of Io science could still be done from afar. As it stands now, a dedicated Io mission looks a ways off (definitely not before a Europa or Titan mission). However, with this delay, it is looking more and more likely that JIMO will be cancelled altogether.

Planetary Society on latest Mimas, Enceladus, and Rhea views

The Planetary Society has an article up on there website by Emily Lakdawalla on the latest views of Rhea, Mimas, and Enceladus taken a few weeks ago after the Huygens landing. Some great points are made, like the youthful surface of Enceladus, the non-spherical shape of Mimas (which has hampered my efforts to create a map of that world), and polygonal craters of Rhea. However, what I like best is the explanation of how images are released to the public from Cassini.

I am a bit surprised she didn't highlight the view of Mimas with Hershel on the terminator which, IMHO, is the best ISS view of these moons during rev C. Also interesting to note is the lack of the Rhea mosaic. I guess after the Iapetus incident where the Planetary Society posted processed Iapetus images before SSI and NASA had a chance to, I'm not surprised.

Tuesday, February 01, 2005


Wikipedia is now indicating that S/ 2004 S 5 now has the provisional name Polydeuces. According to Encyclopedia Mythica, Polydeuces was the twin brother of Castor. Polydeuces, the moon, is 5 km across and orbits 377,000 km from Saturn in 2 days and 19 hours. Polydeuces orbits in Dione's trailing Lagrangian point (L5). Another satellite, Helene, discovered by Pierre Laques and Jean Lecacheux in 1980, orbits in Dione's leading Lagrangian point (L4).

Three other Saturnian satellites have been named in the last month. Methone and Pallene orbit Saturn between Mimas and Enceladus and, like Polydeuces, were discovered by Cassini last year. Narvi was discovered in 2003 by Scott Sheppard and his team at the University of Hawai'i and is one of the numerous irregular outer satellites of Saturn. Three satellites found near the F-ring discovered by Cassini await confirmation and naming. It remains to be seen whether these moons are permanent or are just transient ring clumps.

New Raw images

Some additional raw have been added today on the JPL Raw images page. Here are some links to a few of my favorites:

Mechanism for Tidal Heating on Titan

Bruce Moomaw of posted a very interesting message on the MER Forum yesterday regarding a possible mechanism for tidal heating on Titan. Bruce Bills and Francis Nimmo of Goddard Space Flight Center, UC-San Diego, and UCLA had an abstract in last years LPSC suggesting that the near 5:2 mean motion resonance between Jupiter and Saturn might be enough to maintain Titan's non-zero orbital eccentricity. This would open the door for tidal heating and subsquent cryovolcanic activity, as hinted at by RADAR and ISS data from Cassini.

Edit: I should make a correction that "Mongo" over at the MER Forum actually brought up this abstract a few weeks ago and the post by Bruce was regarding bringing that abtract up with Jonathan Lunine.

Impact Central

CICLOPS has released a global resolution image of Rhea taken just after the Huygens landing a few weeks ago. This view shows wispy streaks, not unlike those seen on seen on Dione which turned out in images taken in December to be lanes of horst and grabens. At this illumination angle, it is difficult to tell whether the same is true for Rhea's wispy terrain. You may also note the linear bright streak at the bottom of the image which may be a fracture or a crater ray. I would go with the latter.

Monday, January 31, 2005

Sunstriped Saturn

CICLOPS posted a new picture of Mimas against a ring-shaded Saturn, reminiscient of the special release image from October. This view was taken during the most recent periapse a few weeks ago.

Rock 'n' Roll is out of this world!

"Music has always been at the centre of cultures all over the world and it will continue to play an important part in thousands of years time,” said Mick Jagger on the Music2Titan project.

"Music has a role in the same way as technology and science in reflecting the age we live in and generally exploring new areas beyond the accepted boundaries and beyond Earth," said Jagger.

More at the link above.

Sunday, January 30, 2005

The latest on DISR images

Leo Enright of Irish TV and Bruce Moomaw of on Oliver Morton's Martian Blog are reporting on images taken by DISR from below 500 meters in altitude. These images were not taken as full triplets, but as individual HRI frames taken every 8 seconds. Given the loss of channel A and a descent rate of 5 m/sec, this would mean about 3 or 4 image. Anyways, it sounds like these images have been on the ground so it will be interesting to see what they show (especially the one after the spotlight was turned on). Not quite sure what these images will show, whether we would see individual pebbles or see the nearby bright material, but it is good to know they are on the ground.

Speak of ground, that same blog page is reporting that the bright spots that appear in the ground frames may not be image artifacts but maybe real. What could these be? My favorite explaination is that Huygens landed near a small runoff stream and the bright spots are stuff in the stream.