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randb
2006-Jan-31, 08:17 AM
I'm sure most of you have seen pictures of Titan's surface....Why are the images...so bad???? Is it cuz of signal transmission problems??? Explain plz....

mantiss
2006-Jan-31, 02:05 PM
I'm sure most of you have seen pictures of Titan's surface....Why are the images...so bad???? Is it cuz of signal transmission problems??? Explain plz....

Well, Cassini-Huygens was launched in 1997, which meant it was built in the years leading to that, figure out 1994-1996. In those years, 1MPixel was about as good as you could get on a shoestring budget. And of course there is no possible hardware upgrades while en-route.

Also I am sure the raw data could be further enhanced and refined by the same guys who re-processed the Venera Images of the Soviet Venera Landers in the 70's and 80's

jkmccrann
2006-Jan-31, 03:15 PM
Which images are you referring to exactly?

Because isn't the atmosphere of Titan one of the densest in the Solar System - behind that of Venus, and when one thinks of Titan's distance from the Sun, its only getting a fraction of the sunlight we're receiving here on Earth.

So, given the lack of light reaching Titan and the density of the atmosphere, I doubt that there'd really be a heap of light on Titan for Huygens to be utilising, and as mantiss mentions, we're talking about 10yr old+ hardware.

Doodler
2006-Jan-31, 08:57 PM
I'd say it was the haze more than anything. All the megapixels you can pack into a camera aren't going to take any clearer pictures in smog.

01101001
2006-Jan-31, 10:07 PM
I'd say it was the haze more than anything. All the megapixels you can pack into a camera aren't going to take any clearer pictures in smog.
Mmm, megapixels...

The actual device was better measured in kilopixels. DISR Facts (http://www.planetary.org/saturn/huygens_inst_disr.html#facts) lists the apparently total-used 464-by-254-pixel CCD optically split into 3 views: high-res 160x254; medium 176x254; side-looking 128x254. That's 118 kilopixels. That's approximately 40 kilopixels per type of image.

If it captured more detail, more data, I don't see how that would have helped because the short-termed transmission bandwidth (only 4800 bits per second) was fully occupied with the images that were captured. (Well, as it turned out a lot of the images were identical images from on the ground, but they were a serendipitous bonus. The mission was designed to transmit critical images near-real-time, so that they could be received during descent, before Huygens crashed to the uncertain surface.)

Launch window
2006-Jan-31, 10:31 PM
Yes its true you compare the pics of the Russian Veneras, or picture quality of Apollo missions or MER Rovers to Titan photos and then Saturn's moon doesn't seem like the ultimate postcard anymore

but I'll still be a massive fan of Cassini and Huygens at Titan !
and I still think its one of the best missions ever launched, why ?
It took many missions by both the USA and Russia before one single photo was returned from Venus-surface, there were the early Venera, Mariner probes and Zond craft. The Cassini-Huygens was a one shot mission to study the Saturn rings and explore moons of Saturn, and land in one the most distant and exotic worlds in the solar system.
The ESA/NASA scientists only released raw pictures, yet after the pictures were processed and layered they looked much beter. the Moon Titan is very far away from the Sun and there is simply not that much light to work with either, and Titan being so cold, infra-red night vision wouldn't do much help and here is also the eternal thick mist of hydrocarbons floating in the atmosphere, hanging like a murky London fog or L.A smog over everything, the world of Titan has at best only a few percent of the sunlight as Earth, and even less thanks to the thick atmosphere our space optical cameras, such as the ones on the rovers that are simply would not work at all, then there is the fact that the camera wasn't the most important instrument either, the gas analyzer and such take up energy and uplink bandwidth too, the ACP (Aerosol Collector and Pyrolyser) collected aerosols to be analysed by the Gas Chromatograph and Mass Spectrometer experiment. It is equipped with a deployable sampling device that will be operated twice during the descent.
It had many other instruments apart from a 'pretty-picture camera' like the Gas Chromatograph and Mass Spectrometer is a versatile gas chemical analyser designed to identify and quantify various atmospheric constituents, it is also equipped with gas samplers which will be filled at high altitude for analysis it is cryogenically cold on Titan, which will inhibit batteries and shorten their life severely without a heater, which would itself run the batteries down quickly, you can read back on the original thread - the Huygens probe had only 3 hours to collect all the data it could before it was severed from its ability to send anything back. After that Cassini would not get in contact again as it was over the horizon.

randb
2006-Feb-01, 12:16 AM
Thats what I thought too....Bandwidth problems... From the images, it doesnt seem like there is a lack of light or that its too foggy.....



Mmm, megapixels...

The actual device was better measured in kilopixels. DISR Facts (http://www.planetary.org/saturn/huygens_inst_disr.html#facts) lists the apparently total-used 464-by-254-pixel CCD optically split into 3 views: high-res 160x254; medium 176x254; side-looking 128x254. That's 118 kilopixels. That's approximately 40 kilopixels per type of image.

If it captured more detail, more data, I don't see how that would have helped because the short-termed transmission bandwidth (only 4800 bits per second) was fully occupied with the images that were captured. (Well, as it turned out a lot of the images were identical images from on the ground, but they were a serendipitous bonus. The mission was designed to transmit critical images near-real-time, so that they could be received during descent, before Huygens crashed to the uncertain surface.)