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mkk707
2009-Aug-24, 12:21 PM
Folks,

The issue of craters on Titan has been discussed at length, also in the BAUTforum. I have been mulling an idea I had back in October 2004, when the first SAR radar images of the Saturn moon Titan were produced by the Cassini spacecraft. I did not find a recent thread to which to append this, so I open this new thread.

I have written it all in a post on my blog:

http://www.scilogs.eu/en/blog/go-for-launch/am-i-the-only-one-who-sees-a-crater-here

I am really interested in people's opinion on this. Maybe some of you have more experience that I have with interpreting SAR images of body surfaces (Yes, I am aware that that is a non-trivial task, hence my query).

Am I seeing things? Is it out of the question that there is a visible crater already in the October 2004 radar image? Or might I actually be on to something here?

I know that posting links to own blogs may meet with some mistrust, as some people might do that to publicize weird ideas or even SPAM. I assure you that this is not my intent.

It is simply that I have written my train of thought in my blog, complete with graphs and images. The most efficient way of conveying that information is by posting the link to my blog --- I could have cut and pasted the text here, but images and hyperlinks (mostly to NASA/JPL sites) might be lost then.

Jerry
2009-Aug-26, 02:58 AM
Welcome to the BA forum mkk707:)

Be sure to read the forum rules - generally posting references to your own blog is discouraged if not forbidden, but the topic is a good one.

The debate is going to rage on about Titan for decades: What are craters and what are caldara? Is that a fault line or a river? Are those lakes, or are those smooth lava flows? What the heck is Titan made of? It would be a little easier to answer the other questions if we knew the answer to this last one.

Yes, it is easy to pull images out of images that are not real. Most of the 'first releases' are uncalibrated jpeg images - these are lossy, and if you try to blow them up and enhance the images; more likely than not you will identify non-existent features.

If a discussion is not generated here, there are lots and lots of great discussions on what is and what is not on Titan in the pages of Unmannedspaceflight.com website - Doug Ellison's gem. Real Titan experts hang out there - and they don't always agree. Also, join the Planetary Society and follow Emily's blog.

mkk707
2009-Aug-26, 05:26 AM
Welcome to the BA forum mkk707:)

Be sure to read the forum rules - generally posting references to your own blog is discouraged if not forbidden, but the topic is a good one.

The debate is going to rage on about Titan for decades: What are craters and what are caldara? Is that a fault line or a river? Are those lakes, or are those smooth lava flows? What the heck is Titan made of? It would be a little easier to answer the other questions if we knew the answer to this last one.

Yes, it is easy to pull images out of images that are not real. Most of the 'first releases' are uncalibrated jpeg images - these are lossy, and if you try to blow them up and enhance the images; more likely than not you will identify non-existent features.

If a discussion is not generated here, there are lots and lots of great discussions on what is and what is not on Titan in the pages of Unmannedspaceflight.com website - Doug Ellison's gem. Real Titan experts hang out there - and they don't always agree. Also, join the Planetary Society and follow Emily's blog.

Thanks.

I am aware of the open issues, and I am more than aware of the pitfalls one can encounter when interpreting image data. But those are rather generic comments.

All I was asking for here is a general impression. Everyone I have been showing the data to so far appeared to agree that there seems to be a circular feature there.

I have been following the press and other discussions and never came across anything related to this specific image, with reference to that feature, which is why I brought it up myself.

I also have access to the raw data that went into that image, but processing that is a highly non-trivial task, and before I embark on that, I would like to have some assurance that I'm not completely off on a wild-goose chase here.

mkk707
2009-Aug-26, 07:11 AM
Welcome to the BA forum mkk707:)

Be sure to read the forum rules - generally posting references to your own blog is discouraged if not forbidden, [....]

To avoid a discussion on formal issues, or any hard feelings, I propose to go about this differently. I thought it would make things easier by posting jsy the link to the place where I had laid out my ideas, but if that is contrary to the rules here, I certainly don't want to offend anyone.

In short:

Here is a SAR (synthetic aperture radar) image taken by the Cassini spacecraft in late October 2006:

http://photojournal.jpl.nasa.gov/catalog/PIA06988

Here is a larger jpeg version of the same image:

http://photojournal.jpl.nasa.gov/jpeg/PIA06988.jpg

My question is: Do you or do you not perceive a large circular feature in the leftmost third of the image? I.e., a feature that would e.g., be consistent with an eroded impact crater.

I have indicated the feature that I am referring to in the following link. Don't click there if you don't want your impression to be biased.

http://www.kosmologs.de/kosmo/gallery/4/PIA06988Hwithcircle.jpg

So .... which is it?

Yea or Nay?

mkk707
2009-Aug-26, 04:48 PM
Here is a SAR (synthetic aperture radar) image taken by the Cassini spacecraft in late October 2006:

http://photojournal.jpl.nasa.gov/catalog/PIA06988

Here is a larger jpeg version of the same image:

http://photojournal.jpl.nasa.gov/jpeg/PIA06988.jpg

My question is: Do you or do you not perceive a large circular feature in the leftmost third of the image? I.e., a feature that would e.g., be consistent with an eroded impact crater.

I have indicated the feature that I am referring to in the following link. Don't click there if you don't want your impression to be biased.

http://www.kosmologs.de/kosmo/gallery/4/PIA06988Hwithcircle.jpg

So .... which is it?

Yea or Nay?

I've been digging into this a bit deeper and managed to find the solution. First, I found a higher resolution radar image on this great web site of the LPL in Arizona.

http://pirlwww.lpl.arizona.edu/~perry/RADAR/

Here is the region in question again, extracted from the material in the above web site. I think it is pretty obvious that there is a circular feature there, not just an optical illusion.

http://www.kosmologs.de/kosmo/gallery/4/TitanFeature26Oct2004Extract.jpg

Then I came across a NASA-JPL press release from February 2007, two and a half years after the original radar image was made and released. This explained why I had not found it during my research in the time after I was so intrigued by the original image.

http://photojournal.jpl.nasa.gov/catalog/PIA09176

The solution: This feature was identified as a cryovolcano, a volcano that ejects ice, not lava. It was then named Ganesa Macula. A cryovolcano is obviously even more exciting than a crater, with farther-reaching implications. Had I even harbored the notion back in 2004 that I was actually looking at a cryovolcano, I would have been excited out of my wits.

Science is exciting, folks! I love it.