Yes, I agree with your assesment, but Casinni isn't orbiting Titan 100km up. It is racing by at 10 times that distance and has no "fuzz free" wavelengths to see the surface. Don't expect to see anything approaching the clarity of Huygens taken from orbit. That is why it is incredible with respect to meters per pixel.<br /><br />No, the processing won't improve their resolution. What it will do is put the small pictures together into a mosaic that would be roughly equivalent to a larger imager but with a much wider aperature. I don't see the big deal that they chose to put together smaller images as opposed to flying and uplinking something like the Pancam. So we have to wait a few days while the film is at the drug store. Big deal. In the end we will have a vista a few clicks on a side with incredible resolution.<br /><br />I don't really care that my 4M pixel camera can take much clearer pictures, it's not a few km above Titan is it?
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Thanks, glad to hear it was basic FM. The packets are probably heavilly FEC'd, so that should help too.
Oh dear. Life just got tougher. I guess we'll find out just how good those radio telescopes are. Didn't the A channel have an ultra stable osscilator on the lander, or was that just on the orbiter? Must be on the lander as well. I wonder if that will help any? Sure will be impressive if they can pull data out of something like that from that far away.
<i>First 'Best-Guess' View of Huygens Landing Site<br />January 18, 2005<br /><br />A view of Huygens' probable landing site based on initial, best-guess estimates. Scientists on the Huygens Descent Imager/ Spectral Radiometer (DISR) science team are still working to refine the exact location of the probe's landing site, but they estimate that it lies within the white circle shown in this image.<br /><br />The Descent Imager/Spectral Radiometer is one of two NASA instruments on the probe. </i> <div class="Discussion_UserSignature"> </div>
I thought the only thing the groung based telescopes could help with was recreating the doppler wind data. Is there actually hope of obtaining the channel A lost data? Any articles to read on this?
There was a very interesting program on the science channel on at least 2am mountain time sunday jan 16th and may be on again as part of Discoveries this week titled "target: titan" On it they talked all about Titan and to several scientists and said some very interesting things on it, they talked about how all of the radio telescopes were trained on huygens. When it transmiteed back to cassini, they were monitoring and the signal was just strong enough to receive from earth (surprisingly) and one of the ESA scientists said they were pretty sure they could reconstruct the data, so let's hope they can! I learned more on that program than I ever have about Titan, more comprehensive and in depth discussions... Here's a link I found!!<br /><br />http://www.exn.ca/dailyplanet/story.asp?id=2004062251<br /><br />more links and video archives, some from the episode in question.<br />I can't locatet the cllip yet where they talk about the lost data, if they<br />even show it...<br /><br /><br />http://www.exn.ca/dailyplanet/archivelist.asp
Grégoire,<br /><br />From what I have read, the images that were transmitted on the faulty channel cannot be reconstructed. I don't have the links. But I browsed through many articles to find out that the other images are trully lost. Some data can be reconstructed by the Radio telescopes but not the images (I am not sure why).
<br /><br />Here is some more videos from that airing (orig jan 14th)<br /><br />http://www.exn.ca/dailyplanet/view.asp?date=1/14/2005 one talks about the missing channel 'a' but not the clip where they say they can recover it from earth
<i>Atmospheric features in Saturn's north polar region are revealed in spectacular detail in this Cassini image, taken in the near infrared spectral region, where methane gas is not very absorbing. The dark shadows of Saturn's rings drape across the planet, creating the illusion of atmospheric bands. Dots of bright clouds give the appearance that this is an active place.<br /><br />The image was taken with the Cassini spacecraft wide angle camera on Dec. 14, 2004, at a distance of 717,800 kilometers (446,100 miles) from Saturn through a filter sensitive to wavelengths of infrared light centered at 939 nanometers. The image scale is about 43 kilometers (27 miles) per pixel. </i> <div class="Discussion_UserSignature"> </div>
It would be fantastic if they could, but I think they are only talking about using the phase/doppler shift of the carrier signal to infer something about the location/movement of the probe - data that was on the lost radio channel . The high frequency data channel is probably lost in the noise..<br /><br />As someone who has been involved in large coding projects (100,000 lines +) while I understand how easy it is for bugs to creep in, I do think the programming bug that effectively did not switch on the second channel should have been picked up on a project of this size/budget. Sadly, too often, the bigger the bureaucracy, the more mistakes like this you have - small keen teams often do better.<br /><br />While Huygens is sucessful, I do think that money is better spent on a wider range of cheaper projects. For example we could have a 2nd "new horizons" probe to Uranus & several KBOs for less than the $600mil (cheapish) cost of NH1, if we do it now. Or another SMART-1 probe (<$100mil), maybe to Venus..<br /><br />They are proposing to spend maybe $10bil on JIMO - I think that could be a mistake..<br />
I think the high-frequency data from the lost second channel will be lost in the noise from what we recieved back on earth, although of course I would be delighted if they could make something of it.<br /><br />Regarding image quality on Huygens - in hindsight could that have been done better?<br /><br />I realise there are constraints - 80's hardware, limited batteries, 8k bit channel, etc, but here are my casual observations..<br /><br />Much higher resolution CCD's were available at the time - Cassini had a 1 megapixel unit. Low res data could have been transmitted during descent, but hi-res data could have been stored & broadcast after landing. As it is, the radio spent a lot of time sending identical images of the landing site. Furthermore, why the assumption that the probe will be destroyed on landing? Why not switch off Huygens when Cassini dissapears below the horizon, and switch it on for the next day? (titan's day is 16 days long..) The batteries lasted many hours after the landing, and the craft did cruise in standby mode for 16 days, so this should have been possible.<br /><br />I think they could have returned all the data we got anyway up to the landing, and designed a 2nd phase with more data being sent, with little change to mission profile/weight/etc..
><i>Furthermore, why the assumption that the probe will be destroyed on landing?</i><p>Because nobody knew the exact composition of the atmosphere or the surface winds and hence couldn't predict the landing speed with any accuracy. There were some who thought that the surface winds could have been a couple hundred kph. Also, nobody could predict where the probe would land. It might have landed on jagged outcrops or have tumbled into a cravasse - there was some hope that it might survive on the surface, but I don't think even the most optimistic would have expected it to last so long.<p>><i>Why not switch off Huygens when Cassini dissapears below the horizon, and switch it on for the next day? </i><p>But where would Cassini be in 16 days, it would be many tens of thousands of miles away. Hygens' transmitter would likely not be powerful enough for Cassini to get a lock on its signal.</p></p></p>
<i>Because nobody knew the exact composition of the atmosphere or the surface winds and hence couldn't predict the landing speed with any accuracy. There were some who thought that the surface winds could have been a couple hundred kph. Also, nobody could predict where the probe would land. It might have landed on jagged outcrops or have tumbled into a cravasse - there was some hope that it might survive on the surface, but I don't think even the most optimistic would have expected it to last so long.</i><br /><br />Ok, but why assume that *will* happen? As it turned out Huygens was able to transmit for another 1/2 hour from the surface - at that stage hi res pictures could have been sent, with little extra hardware cost..<br /><br /><i>But where would Cassini be in 16 days, it would be many tens of thousands of miles away. Hygens' transmitter would likely not be powerful enough for Cassini to get a lock on its signal. </i><br /><br />I would like to know if that is true for sure..<br />
><i>...with little extra hardware cost...</i><p>But, as you would know from your experience, the actual hardware costs are minor in comparison to the additional testing and the software development cost. Also, for space hardware, every few grams matters. But more importantly, we lucked out, if the probe had landed a little closer to the rocks in the field of view then we would have had out of focus, high-res pictures of a rock.</p>
But I have been thinking in terms of ideas that add very little to the overall hardware/software demands. <br /><br />Another idea that gets a lot more out of a video data stream is variable jpg compression & only transmitting the signal difference between certain frames. That way you can use hi res CCDs then compress-until-it-fits the 8K data channel. When there is a lot of data/change in the pictures you compress a lot, but if certain cameras are not returning any or little change in the pictures, or if the picture has no detail, more channel space is available to send either hi-resolution or even pre-recorded data. <br /><br />Such compression methods are used in modern digital TV broadcasts - if one channel has relatively static data then more space is available to one with more motion/detail.<br /><br />Such methods were certainly known about & in use in the late 80's when Cassini was designed..<br /><br />Is there a spec on the processor/speed/mem used on Huygens anywhere?<br /><br />I agree that luck plays a big part, I just wonder if more could have been done with the good luck we apparently had..<br /><br />In both Voyager/Galileo the craft were re-programmed "on-the-fly" as code was later developed to improve the systems, or to correct errors..<br />
One thing I dont understand - why are the triplets out of sequence? The early pictures show the landing site! Is this just some artifact of the transmission process? <br /><br />If I didnt know any better, I would say that final picture of the rocks was just a "joke" by the programmer, a frame to put in when the data/checksum fails for that camera.. 
<br />
<br /><i>"Low res data could have been transmitted during descent, but hi-res data could have been stored & broadcast after landing. As it is, the radio spent a lot of time sending identical images of the landing site." -- sky5000</i><br /><br />There was no way to predict when the best pictures could be taken. I think the most meaninful images are the ones from around 10km, showing what looks like drainage channels and coastline. A little higher, Huygens was in cloud. At gound level, Huygens could have been sitting in fog or covered in slime from a dunk in a Titan sea. <br /><br />Pointing out how many images were "wasted" by being taken in haze just illustrates this problem of knowing when the best time to take a high definition picture whould be. I think the best path was the one followed -- take as many pictures as possible at a variety of elevations. This sacrifices quality but gives a better chance that <b>some</b> of the images will be taken at the ideal time in the ideal direction. <br /><br />Using this method, I think they succeeded in getting a stunning panarama of a very intriguing set of features on Titans surface. If anything I would have liked a high resolution shot of that scene, not of the relatively uninteresting terrain seen at ground level. No one knows when the most interesting shots would be taken and so would not know how to program the taking of such shots. <div class="Discussion_UserSignature"> </div>
My point is that these are automatic methods - like the ones used to compress multiple channels on Digital TV. There are known ways (of varying complexity) to transmit less data when a picture has little detail,or is not very different to its predecessor, or only different in special ways (motion compression).. <br /><br />Furthermore the crafts computer "knows" when it has come to rest - and can act accordingly - ie. transmit more details slowly, or relay older pictures..
sky5000-<br /><br />Here are a couple of details from p 21-25 of this pdf on the DISR<br />http://www.rssd.esa.int/SB/HUYGENS/docs/SP1177/tomask_1.pdf<br /><br />CPU: MA31750 microprocessor running at 12 MHz , 128 kbytes of program RAM, 64 kbytes of data RAM, 128 kbytes if PROM and 64 kbytes of EEPROM.<br />There was a 1.5Mbyte frame buffer and 3 Data Management Channels via Actel 1020 FPGAs.<br /><br />Images were acquired at 12 bits/pixel, which was reduced to 8 bits after being flat-field corrected. Before being transmitted to Cassini the images were compressed with a modified JPEG algorithm to 3:1 to 6:1.
<font face="”verdana”"><br /><br /><br />I am both excited and disappointed with the Cassini: Huygens mission!<br /><br />I am disappointed that we did not do more, with respect to exploring the surface the way we are exploring the surface of Mars.<br /><br />I am 38 years old, and I will be 50 years old by the time another craft reaches Titan. What will the next mission accomplish, if there is a next mission.<br /><br />There is a huge amount of people interested in exploring the final frontier, and we should find some way to accelerate the processes in getting in done! <br /><br />We should be launching 100’s of reconnaissance crafts per year! If the problem is funds, then we should be soliciting funds from the billions of people that are willing to fund an aggressive program. <br /><br />What about these rovers that did? Get them on an assembly line and mass-produce them! Maybe we need a network of communication satellites too. We have hundreds of satellites around earth, why not mars?<br /><br />We need to get off our duff, and build a base on the moon! Moon to Mars, Moon to Titan, etc… <br /><br />How do we get the ball rolling people?<br /><br />TY<br /><br /><br />http://Jatslo.com/<br /><br /><br /></font><br />
You might be on to something by bringing up viscosity. Titans' surface low spots might be filled with polymeric substance with non-Newtonian fluidic characteristics (like catsup). If a 'fluid' took 50,000 years to smooth out after an abrupt thwack (like a meteor impact), but if you left a hammer on the surface and it disappeared beneath the surface after 6 months, you might have something that, although pretty exotic in our experience, might be ubiquicious on Titan. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
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