Comments on: Titan Looking Earthly http://wanderingspace.net/2007/03/peering-beneath-the-veil-at-titan/ Imaging the bodies of our Solar Sysytem Thu, 09 Feb 2012 00:33:41 +0000 http://wordpress.org/?v=2.5.1 By: thomas http://wanderingspace.net/2007/03/peering-beneath-the-veil-at-titan/#comment-506 thomas Thu, 15 Mar 2007 15:23:36 +0000 http://wanderingspace.net/?p=259#comment-506 Ah… so essentially the camera was weak for the same reasons it didn’t stay awake very long. I guess it is safe to assume that any percieved weaknesses in instrumentation have their reasons. It is also true that I totally forgot that the technology was at the very latest from 1995! Thinking back, I believe our first digital camera at the Chopping Block was around 1997. Ah… so essentially the camera was weak for the same reasons it didn’t stay awake very long. I guess it is safe to assume that any percieved weaknesses in instrumentation have their reasons. It is also true that I totally forgot that the technology was at the very latest from 1995! Thinking back, I believe our first digital camera at the Chopping Block was around 1997.

]]> By: Gordan http://wanderingspace.net/2007/03/peering-beneath-the-veil-at-titan/#comment-504 Gordan Thu, 15 Mar 2007 09:17:45 +0000 http://wanderingspace.net/?p=259#comment-504 Two reasons for the image quality we got: 1) Mass. A color or higher resolution camera would weigh much more than this and getting just one extra kilogram to Titan is not as easy as it seams. The Cassini-Huygens spacecraft was already one of the heaviest planetary probes ever launched. Keep in mind we're talking about 1995 technology, for all practical purposes today's digital cameras didn't even exist then and that argument quickly falls short. 2) Data transmission bitrate. The bandwidth of the Huygens transmitter was something like 8 kbps, that's 7 times slower than a 56k modem! The image data wasn't the only data to share this bandwidth and yet it took probably 80% of the total link capacity (for example the microphone sacrificed its output just so it also wouldn't take too much precious bandwidth away from the cameras). How many image pixels can you squeeze through a 8kbps channel over the course of 3 hours? Even if the camera was a much better one, you would have no possibility of sending that many megapixels back in the short time the lander was supposed to live. Either you'd get one large image or smaller mosaic images and I'd rather have the latter. There are realistic constraints to why something was done the way it was and people often forget all the severe limitations involved. The most severe limitation in case of Huygens (as well as all space probes for that matter) was mass and that dictated everything else: power budget, instrument capabilities and downlink rate. We're still in the age of chemical propulsion and if that doesn't change soon, mass will still be a limiting factor, resulting in the need to do complex interplanetary swingbys just so you even reach your destination (Cassini, Galileo, MESSENGER, Rosetta, etc...). Two reasons for the image quality we got:

1) Mass. A color or higher resolution camera would weigh much more than this and getting just one extra kilogram to Titan is not as easy as it seams. The Cassini-Huygens spacecraft was already one of the heaviest planetary probes ever launched.
Keep in mind we’re talking about 1995 technology, for all practical purposes today’s digital cameras didn’t even exist then and that argument quickly falls short.

2) Data transmission bitrate. The bandwidth of the Huygens transmitter was something like 8 kbps, that’s 7 times slower than a 56k modem! The image data wasn’t the only data to share this bandwidth and yet it took probably 80% of the total link capacity (for example the microphone sacrificed its output just so it also wouldn’t take too much precious bandwidth away from the cameras).
How many image pixels can you squeeze through a 8kbps channel over the course of 3 hours? Even if the camera was a much better one, you would have no possibility of sending that many megapixels back in the short time the lander was supposed to live. Either you’d get one large image or smaller mosaic images and I’d rather have the latter.

There are realistic constraints to why something was done the way it was and people often forget all the severe limitations involved. The most severe limitation in case of Huygens (as well as all space probes for that matter) was mass and that dictated everything else: power budget, instrument capabilities and downlink rate. We’re still in the age of chemical propulsion and if that doesn’t change soon, mass will still be a limiting factor, resulting in the need to do complex interplanetary swingbys just so you even reach your destination (Cassini, Galileo, MESSENGER, Rosetta, etc…).

]]> By: thomas http://wanderingspace.net/2007/03/peering-beneath-the-veil-at-titan/#comment-502 thomas Wed, 14 Mar 2007 20:42:49 +0000 http://wanderingspace.net/?p=259#comment-502 My guess would be power. Assuming budgetary restrictions, chances are that they only provided enough power for the probe to descend, land and transmit from the surface for just enough time to collect the data they wanted. If you think about the cost of it lasting longer, it would need to last WAY longer than just a few days to make any worthwhile observations. Additionally, the rovers collect solar power, something most likely less abundant on a more distant and cloudy Titan. What I wonder more is why they couldn’t manage a better damn camera on there. The resolution is so low and reminds me of the images from Venus taken over 30 years ago by the Russians. What I wouln’t have given to have a camera on there that could look up and all around. Instead we got one singel image of the ground and some icy stones. My guess would be power. Assuming budgetary restrictions, chances are that they only provided enough power for the probe to descend, land and transmit from the surface for just enough time to collect the data they wanted. If you think about the cost of it lasting longer, it would need to last WAY longer than just a few days to make any worthwhile observations. Additionally, the rovers collect solar power, something most likely less abundant on a more distant and cloudy Titan.

What I wonder more is why they couldn’t manage a better damn camera on there. The resolution is so low and reminds me of the images from Venus taken over 30 years ago by the Russians. What I wouln’t have given to have a camera on there that could look up and all around. Instead we got one singel image of the ground and some icy stones.

]]> By: Mark http://wanderingspace.net/2007/03/peering-beneath-the-veil-at-titan/#comment-494 Mark Wed, 14 Mar 2007 10:56:16 +0000 http://wanderingspace.net/?p=259#comment-494 What I've always wondered is, why did the Huygens lander only "survive" for such a short time? Is it that harsh on Titan? I mean, we have rovers faffing around on Mars for years, and Huygens only survived what, 2-3 hours max? What I’ve always wondered is, why did the Huygens lander only “survive” for such a short time? Is it that harsh on Titan? I mean, we have rovers faffing around on Mars for years, and Huygens only survived what, 2-3 hours max?

]]>