[X] My Assistant

[volcanopele]

Well, for those who really like RADAR SAR swaths, today is a good day for you. The T13 RADAR swath from April, THE ENTIRE SWATH, has been publically released on the Photojournal.

Titan (T13) Viewed by Cassini's Radar - April 30, 2006
http://photojournal.jpl.nasa.gov/catalog/PIA08552

PIA08604: Xanadu's Meandering Rivers
http://photojournal.jpl.nasa.gov/catalog/PIA08604

PIA08605: Titan's Geological Goldmine - Radar Movie
http://photojournal.jpl.nasa.gov/catalog/PIA08605

[elakdawalla]

I have yet to come across a "startling new" interpretation of Titanian geology that (upon my asking him) Ralph Lorenz hasn't been able to point to as being predicted in some past book or paper of his. I think I'll him about the caverns thing and see what he has to say.

All.... if I am not mistaken I believe Ralph Lorenz mentioned this in conjunction with an early Titan theory regaring karst terrain...... check his book 'Lifting Titan's Veil'.

I thought I remember reading that Ralph predicted that there would be no karst terrain and no caves on Titan...

Yes, that was my recollection as well. It had to do with the ability of liquid methane/ethane to erode water ice. There had been some graduate paper that suggested easy erosion. As it turned out that data was incorrect.

OK, here's the result of my queries, which I just posted in the blog:

Ralph replied that "I think [Wall] is referring to the porosity that may be indicated in the radiometry polarization data, which isn't published yet." He added that he had indeed talked about caverns on Titan -- in the form of karst terrain -- in his book Lifting Titan's Veil, and that the idea had "originated with Jonathan Lunine in the late 1980s, but that was based on some lab data that subsequently proved to be wrong. We discussed solution erosion on Titan (and showed it to be tiny) in "Erosion on Titan: Past and Present" (Lorenz and Lunine, 1995, PDF format), although we didn't mention caverns specifically."

Ralph had copied Steve Wall and Jonathan Lunine. Jonathan added that the lab data he'd based his original karst terrain speculation on weren't his, they were "somebody else's published in the refereed literature." He also pointed out that another researcher, David Stevenson, "argued in the early '90s for a porous crust to 'hide' an ethane-methane ocean. It was purely theoretical, and he had one piece of gray [unpublished] literature on this in which he at least speculated about big caverns."

Steve Wall commented that "I confess the language is loose. The reference to porosity is (as Ralph suggests) based on radiometry. Size of the 'pores', and if they extend to anything anyone would call caverns, is debatable."

--Emily

[belleraphon1]

OK, here's the result of my queries, which I just posted in the blog:

Ralph replied that "I think [Wall] is referring to the porosity that may be indicated in the radiometry polarization data, which isn't published yet." He added that he had indeed talked about caverns on Titan -- in the form of karst terrain -- in his book Lifting Titan's Veil, and that the idea had "originated with Jonathan Lunine in the late 1980s, but that was based on some lab data that subsequently proved to be wrong. We discussed solution erosion on Titan (and showed it to be tiny) in "Erosion on Titan: Past and Present" (Lorenz and Lunine, 1995, PDF format), although we didn't mention caverns specifically."

Ralph had copied Steve Wall and Jonathan Lunine. Jonathan added that the lab data he'd based his original karst terrain speculation on weren't his, they were "somebody else's published in the refereed literature." He also pointed out that another researcher, David Stevenson, "argued in the early '90s for a porous crust to 'hide' an ethane-methane ocean. It was purely theoretical, and he had one piece of gray [unpublished] literature on this in which he at least speculated about big caverns."

Steve Wall commented that "I confess the language is loose. The reference to porosity is (as Ralph suggests) based on radiometry. Size of the 'pores', and if they extend to anything anyone would call caverns, is debatable."

--Emily

Thanks for the clarification Emily......

regarding the data the says methane/ethane liquids cannot significantly erode water ice....... we know that the surface on Titan is not just pure water ice....... aside from the hydrocarbon gook, the bedrock is probably a mixture of ices. I note that there are hints of CO2 in the Huygens GCMS surface data. Wonder if any studies have been done with the effect of these liquids on a mixture of ices?????? I can envision a water ice stratum with inclusions of CO2 and ammonia. If these other two materials erode more easily, than you have a recipe for karst terrains and caverns.

Again.... where are the VIMS people???? Have they managed to get a grip on their data and remove the haze contribution to get spectra that are from the surface?

Craig