Cassini/Huygens Mission Update Thread

[gregoire]

There are some intriguing photo stitching efforts being made by amateurs......this being my favourite so far. I'll be interested to see the final processed images from ESA.<br /><br />http://web.mit.edu/bitbucket/Titan/titan_panorama.jpg

 

[grooble]

So where's the beef?<br />

 

[gregoire]

I guess we'll know on the 21st<br /><br />http://www.esa.int/esaCP/SEM15Y71Y3E_index_0.html

 

[rogers_buck]

It may be never if that data was not uplinked from the lander on the B-channel. Given that the microphone had the objective of listening for lightning in the atmosphere, it may not have been on the menu as a ground instrument. The 20th of a second of data for the penetrator might have had higher priority. The data might have been collected and sent back through the un-modulated A channel, etc.<br /><br />I sure wish NASA would put a microphone on its rovers. Something about listening in on an alien world is so compeliing to the imagination.

 

[Leovinus]

Well if the Martian atmosphere is only 1% of Earth Sea Level pressure, would sound carry very far? <div class="Discussion_UserSignature"> </div>

 

[rogers_buck]

Hey, it's Titan. How do you know that round thing isn't a tree?<br /><br />Personally, I think that big round boulder is a hail stone. Having been through a number of Texas hail storms I can easilly extrapolate them to a world with lower gravity, lower temperatures, and a thicker atmosphere. Anyone building a house on Titan will have a really tough job finding insurance for their roof.

 

[thalion]

I doubt those are hailstones; though I'm no expert, what little I know about Titan's atmosphere suggests that there isn't any of the strong convection and condensation that would be necessary for hailstones, even with the lower gravity. This is also why I doubt that there is lightning on Titan, though of course I hope there is, for coolness sake. <img src="/images/icons/wink.gif" />

 

[bobvanx]

>>hailstones<br /><br />dozens of kilometers of atmosphere to fall through, at a relatively low velocity, could build up hailstones. Of something other than water. The atmosphere is very "dry," no H2O in it.<br /><br />I think these things are Titanian stromatolites. With sulfur metabolizers, rather than cyanobacteria. <img src="/images/icons/smile.gif" />

 

[rogers_buck]

Humm. Does anyone know what modulation scheme was used for the data?

 

[rogers_buck]

I understand the "sonar" got a good solid return a few km's above the surface. The speculation being made by the interviewed scientist was that this was a robust cloud layer. Maybe a Titanian thunderhead dish up a few hundred pound amonia/tholin ice balls.<br /><br />Now just for the sake of argument, assume they are hail stones. What might be the tell tale giveaway? If there is a damaged one that could be super-res imaged it might indicate a rough landing and perhaps even show signs of layering? Would there be excavations from outgassing of trapped atmosphere less containable at the higher surface temperatures? How about characteristic aerodynamic shape? <br />

 

[rogers_buck]

>> I think these things are Titanian stromatolites. With sulfur metabolizers, rather than cyanobacteria. <br /> <br />Perhaps they are copralites precipitated from the strange cloud formations that graze on tholins in the atmosphere.

 

[shishka]

A quote from a recent piece in space.com:<br /><br />"The latest images underline the belief that Huygens landed at the shoreline of what appears to be large body of liquid when it ended a seven-year journey, reaching Saturn's largest moon Friday"<br /><br />A large body of liquid? I'm sorry, but from the beginning I was not convince that standing liquid existed, and I see nothing of the data thus far that convinces me otherwise. Am I missing something?

 

[kaisern]

I second that emotion! Give me one high res image for 100 blurry postage stamp images any day of the week.

 

[bobvanx]

>>A large body of liquid?<br /><br />It's the old "if it looks like a duck and quacks like a duck it must be a duck" argument.<br /><br />There are raised, light areas, with channels cut through them, that appear as though they are draining into a broad flat dark expanse.<br /><br />This dark expanse could be "liquid" in the way we are familiar with, ie a low viscosity substance that flows into and fills its container, or it could be something very thick and molasses or even tar-like, or it could be solid and merely be the record of past infilling when it was a liquid.<br /><br />HOWEVER<br /><br />they brought lots of instrumentation that will help answer this question, such as the device that beamed back the data that the probe landed in the equivalent of wet mud. Which then burped a little cloud of methane.<br /><br />So the thing splatted down into something goopy, which releases methane when warmed. They'll use that plus all the other data the got and piece it together whether the probe landed in a Titanian marsh, you'll see.

 

[rogers_buck]

You might add to that the radar return from Casinni's flyby. Cassini failed to detect the teltale flash of a liquid body as it passed overhead, but the radar detected something that the remarkably similar to the return from a body of water on earth.<br /><br />It seems that total satisfaction on this one is hard to garner from the available bits. However, for me the mere fact that the atmospheric composition, the pressure, and the temperature at the surface allow for liquid methane to exist when coupled iwth the evidence you mentioned makes it highly improbable that the large flat areas are liquid and any other explanation far less likely. What a tease...

 

[bobvanx]

>>What a tease... <br /><br />Isn't science <i>fun?</i><br /><br />I think it's great that the men and women working on this have to try to fit all the data together. What a wonderful, amazing journey of discovery for them!<br /><br />I still am amazed that I can turn on my faucet and get hot water, <i>right inside my house.</i> I understand the plumbing, and the water heater, and way the electronic ignition and the natural gas and the water in the tank and the valve in the faucet and the drain in the sink all work together so I can wash my hands in warm water.<br /><br />But it still amazes me.<br /><br />So to be able to turn on my computer, and look at pictures from the surface of a place with an honest-to-goodness atmosphere, and follow the interpretations of the science returns as they work out what all their instruments together tell them, well, that simply blows my circuits.

 

[slappymcb]

<blockquote><font class="small">In reply to:</font><hr /><p>So even though the cameras are low res they are incredible with respect to meters per pixel. You would need something like a Keyhole spy sat with a 10,000x10,000 element CCD to approximate the detail of the worst of the Huygens pictures at high altitude.<p><hr /></p></p></blockquote><br /><br />That's completely incorrect. Our <i>commercial</i> satellites today take 0.5m (per pixel) color imagery from over 100km away. The DISR images were 20m per pixel from only 8-13km away! (See <br />http://www.esa.int/SPECIALS/Cassini-Huygens/SEMA6U71Y3E_0.html ). That is the very definition of "low-res" and why it is called "low-res." It is not "incredible with respect to meters per pixel," not by a long shot! (But that was by design, due to the limited bandwidth). <br /><br />And that magical post-processing everybody is hoping will improve their resolution unfortunately will not happen with these images because they did not use different filters when they took them (or sensors for that matter, except for that spectrometer which only points down and only has about a 4 degree FOV). They can stitch together the panorama, run image filters on it, and cover over the image artifacts, and that's about it. They won't be able to improve the resolution... those pictures will remain either tiny and sharp, or large and blurry.

 

[space_student]

Perhaps I can offer a partial explanation of what went wrong to those who are disappointed with the quality of the images. The original plan called for 700 images to be returned by Huygens, and custom-made software has been developed to stitch these 700 images into a high-resolution, high-quality panoramic mosaic. There was supposed to be a lot of overlap of these images to improve detail and reduce noise. As I understand it, this mosaic was to be released to the public shortly after the images were returned. Unfortunately, things went awry and Cassini's channel A receiver wasn't turned on, resulting in a loss of half of the images and all of wind experiment data. (More on this here: http://www.spaceflightnow.com/cassini/050115science.html , towards the bottom of the page) As a result, image stitching software carefully tweaked for exactly 700 images couldn't be used to quickly produce a panorama, resulting in this sporadic release of tiny raw images and a couple of quickly put together mosaics to the demanding public. While I'm sure existing software can be modified to handle 350 images, the quality of the final product obviously won't be quite as good as it would have been had we received all 700 images, since now there is lot less overlap.

 

[bushuser]

I'll bite at your question, since none of the real engineers responded. Huygens transmits an FM signal, and the data is digitized. Each wave peak corresponds to a "zero" . It becomes a "one" when phase-modulated. So one could hope that portions of that digital data might be recovered by large earth dishes. It may take weeks to review recordings from 18 ground-based observatories and decode what they captured. One experiment, the Doppler windspeed, was entirely dependent on channel B.<br /><br />At least, this is my limited understanding.

 

[slappymcb]

" Each wave peak corresponds to a "zero" "<br /><br />Huh?? That would be AM... I can't find the question you're responding to, but Huygens used (binary) phase-shift keying, i.e. 1 is in phase and 0 180 degrees out of phase with the carrier.

 

[slappymcb]

"There was supposed to be a lot of overlap of these images to improve detail and reduce noise." <br /><br />Very little detail would have been improved the way they did it -- only along the path of trajectory at best (where the high-res looking down overlaps the medium-res camera taken some time prior, except they were also spinning so this would have been marginal). The rest of the panorama would have been no different -- they didn't use different filters or otherwise create any orthogonal data that could be combined (e.g. taking three eight-bit pictures at the same camera position with red, green and blue filters to create one 24-bit color image).

 

[spacechump]

I think space_student was talking about this:<br /><br />http://osl.iu.edu/~tveldhui/papers/MAScThesis/node62.html<br /><br />and this<br /><br />http://ccdastrophotography.com/CCDstacking.html<br /><br />Both techniques could be used to enhance the images.<br /><br />

 

[slappymcb]

(spacechump, I edited my post just as you responded, sorry...)<br /><br />The first technique is just filtering (no data added) and the second requires additional orthogonal data (e.g. the RGB example I gave). DISR did not have different filters so that wouldn't work -- "stack" two or three or a million identical signals and you'll get the same identical signal. You can't add data that you don't have.<br /><br />

 

[spacechump]

Actually you could take a few dozen identical images and average them to fill in spots that are degraded in the other identical images....although that would only take you so far. The image might be sharper overall but the resolution is the same.<br /><br />For the record. I'm not complaining about the image quality. Given that we're see low wavelength images through fog and low light levels I'm surprised they got back the quality they did. I'm very excited to be seeing the surface of Titan!

 

[slappymcb]

<blockquote><font class="small">In reply to:</font><hr /><p>Actually you could take a few dozen identical images and average them to fill in spots that are degraded in the other identical images....although that would only take you so far. The image might be sharper overall but the resolution is the same. <p><hr /></p></p></blockquote>What do you mean averaging "identical images?" (what's the average of 3, 3, and 3? Or the average of 19, 19, and 19?!) That wouldn't sharpen anything at all. And nor would any kind of filtering sharpen it noticeably, because those raw images aren't out of focus, they just lack high frequency data -- so there's nothing to "sharpen" it with! In fact, there will be no noticeable image quality improvements once they've finished "processing" the images, just stitched together panoramas layed out in a bunch of different "cool" projections, maybe, and some derived or artistic-license hand colorizations. So nobody get your hopes up!