Odd Spot on Titan Baffles Scientists

[yurkin]

JPL News Release: 2005-086 May 25, 2005<br /> <br />Odd Spot on Titan Baffles Scientists<br /> <br />Saturn’s moon Titan shows an unusual bright spot that has scientists mystified. The spot, approximately the size and shape of West Virginia, is just southeast of the bright region called Xanadu and is visible to multiple instruments on the Cassini spacecraft.<br /> <br />The 483-kilometer-wide (300-mile) region may be a “hot” spot -- an area possibly warmed by a recent asteroid impact or by a mixture of water ice and ammonia from a warm interior, oozing out of an ice volcano onto colder surrounding terrain. Other possibilities for the unusual bright spot include landscape features holding clouds in place or unusual materials on the surface.<br /> <br />"At first glance, I thought the feature looked strange, almost out of place," said Dr. Robert H. Brown, team leader of the Cassini visual and infrared mapping spectrometer and professor at the Lunar and Planetary Laboratory, University of Arizona, Tucson. "After thinking a bit, I speculated that it was a hot spot. In retrospect, that might not be the best hypothesis. But the spot is no less intriguing."<br /> <br />The Cassini spacecraft flew by Titan on March 31 and April 16. Its visual and infrared mapping spectrometer, using the longest, reddest wavelengths that the spectrometer sees, observed the spot, the brightest area ever observed on Titan. <br /> <br />Cassini's imaging cameras saw a bright, 550-kilometer-wide (345-mile) semi-circle at visible wavelengths at this same location on Cassini's December 2004 and February 2005 Titan flybys. "It seems clear that both instruments are detecting the same basic feature on or controlled by Titan's surface," said Dr. Alfred S. McEwen, Cassini imaging team scientist, also of the University of Arizona. "This bright patch may be due to an impact event, landslide, cryovolcanism or atmospheric processes. Its distinct color and brightness suggest that it may have formed relat

 

[volcanopele2]

Hot spot means that this feature may be warmer than its surroundings, enough that at 5 microns, VIMS is seeing emission from this area along with reflected sunlight. Perhaps an easier way to think about this is for Io, where bright spots were seen by the NIMS and SSI instruments. An example from NIMS is at:<br /><br />http://photojournal.jpl.nasa.gov/catalog/PIA03534<br /><br />The bright spots in the right image indicate areas where emission was seeing coming from Io's numerous. active volcanoes. It is possible that the bright spot seen by VIMS is due to emission from a cryovolcano, which would cause the 5 micron brightness to be higher than it would be if the area had no thermal emission. This could be due cooling water-ammonia lava flows, cracks in the crust of a water-ammonia lava flows, cracks in a water-ammonia lava lake, etc.<br /><br />The problem with interpreting this as a hot spot is that increased solar reflectance at 5 microns can also cause the observed spectrum. So you have to find some way to remove solar reflectance to determine if there is thermal emission (at this wavelength) and how much is it. The easiest way to due to this is to observe Titan at night, where there would be no solar reflectance, only thermal emission (it there is any). The next opportunity to observe the smile at night is next July.<br /><br />BTW, I have a rather lengthy post on my blog about this spot:<br /><br />http://volcanopele.blogspot.com/2005/05/bright-spot-on-titan.html

 

[chew_on_this]

Kinda sucks we couldn't have steered the Huygens probe into this interesting area. I'm still disappointed we didn't get "prettier" pictures from what we did see. Oh well, guess I'll be lucky if I'm a drooling old fogey by the time we get another shot at seeing more of Titans surface.

 

[centsworth_II]

I don't want to get the whole argument started again but I would like to remind you how lucky Huygens was to land where it did. We got shots of an apparent shoreline including multiple ridges, valleys and drainage networks. Huygens landed in an area that looks like a flood plain or a bay at low tide. <br /><br />The mysterious "hot spot" could easily be much less interesting visually on a small scale. If it is due to recent cryovulcanism, it may have appeared as no different than a frozen lake bed or glacier to Huygens. Then we would have had to listen to the complaints about THAT! And if dense fog or clouds are associated with it we may have seen NOTHING! I personally am very happy with what we saw at the Huygens landing site. I would not trade it for any number of birds in the bush. <div class="Discussion_UserSignature"> </div>