The whole cake! Titan Images

wrote:
The tolerances these chips need to meet are considerably higher than
anything within 1AU of earth.
This chip needs to be low noise, low light, low power, and low mass.
They also need to be highly reliable and highly durable.
They need to be custom made to meet the first four requirements.
Meeting the fifth and sixth requirements is a matter of selecting the
best one of as many as you can make.
For starters these are class 0 chips. Meaning they can have no column
defects and no dead pixels.

This assumes the pictures we will be seeing are something else than
*heaviliy* compressed JPG thumbnail size images. Dead or hot pixels are
really nothing compered to high JPG abuse. So far I have seen no indication
that such incompressed material exists here on earth. Does it?

If you double the resolution then you quadruple the number of pixels
and the chance of a defect.

True. You also quadruple the chance of seeing something.

This is all a moot point when compared with the one real factor:
upload speed. Huygens can only upload data at a fixed rate. Given the
probe has a fixed life span in which to transmit the data you have an
absolute amount of information you can upload. a certain amount of the
bandwidth is devoted to the other instruments. This leaves you with a
finite number of pixels you can transmit. There is no data redundancy
with the pictures so you can double that number.

In fact there is a great deal of redundancy. All of the interesting surface
images are of the same scene.

Divide this number by
the number of photos you want to take and you arrive at the maximum
resolution of your imager.

If transmission is the issue, it could have been possible to shoot higher
resolution images and transmit fewer images.

Still, the results are excellent. I just wish they were perfect....

Clear skies
Carsten A. Arnholm
http://arnholm.org/
N59.776 E10.457

"Szaki" wrote in message
...

"George Dishman" wrote in message
...

"Szaki" wrote in message
...

I worked for 12 years for an aerospace company ...
Things are not that tight, ...
Most expensive is the lunch, $10K/ pound or so.

You aerospace guys enjoy your food I guess.
(Were you misled by the subject line?)

You're funny, he!
"LAUNCH" , my mistake!

I just love those typos that still make sense,
probably because I make more myself than most
people ;-)

best regards
George

The one colored image I have seen so far looks like the original monochrome
grayscale shot, converted into a monochrome color shot using image editing
software. The color took many of the details out. Leave 'em in
grayscale...better contrast!!!

Mark
The Catman
^..^

www.geocities.com/mark_rosengarten
Owner/Coordinator of the Neko Ultraportable Solar Observatory
Fun WITH The Sun for Everyone!

In article .com,
wrote:
Given the probe
has a fixed life span in which to transmit the data you have an
absolute amount of information you can upload. a certain amount of the
bandwidth is devoted to the other instruments.

Well ... more or less. But remember the problem with the
high-gain antenna on Galileo. Which they got around by programming new
(better) error-correcting compression algorithms into the main computer?
Effectively a higher data rate through the low-gain system than it was
designed for.

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233

"Aidan Karley" wrote in message
. invalid...
In article .com,
wrote:
Given the probe
has a fixed life span in which to transmit the data you have an
absolute amount of information you can upload. a certain amount of the
bandwidth is devoted to the other instruments.

Well ... more or less. But remember the problem with the
high-gain antenna on Galileo. Which they got around by programming new
(better) error-correcting compression algorithms into the main computer?
Effectively a higher data rate through the low-gain system than it was
designed for.

The high gain comes at the cost of reduced beamwidth.
Huygens was falling through atmosphere and spinning.
It couldn't keep a high-gain antenna aligned on
Cassini.

George

If I remember right, the first fundings for it was about 1986.


--


SIAR
www.starlords.org
Telescope Buyers FAQ
http://home.inreach.com/starlord


"Szaki" wrote in message
...
It was lunched at the end of 1997. Don't tell me it took 10 years to
build?
I would assume the last thing to design and build is the computers and
instruments in order to install the latest technology.
JS


wrote in message
oups.com...

Pham Newen wrote:
No kidding, the images are rather small. I haven't read much in
depth
about the imaging system they use, but damn! How much money was
spent
on this program? Don't get me wrong, I'm sure great science will
come
out of it, but oh well, not the most dramatic of surface photos.
Even
some of the Venus probes from the 70s have some better imagery.
ESA, defend yourself! Casini's imagery has been awesome, so what's
up?

The tolerances these chips need to meet are considerably higher than
anything within 1AU of earth.
This chip needs to be low noise, low light, low power, and low mass.
They also need to be highly reliable and highly durable.
They need to be custom made to meet the first four requirements.
Meeting the fifth and sixth requirements is a matter of selecting the
best one of as many as you can make.
For starters these are class 0 chips. Meaning they can have no column
defects and no dead pixels. Yield rate for these is on the order of 1%.
ESA needs to make a number of these chips and select the best one. If
they want to pick the best of 10 then they need to have 1000 chips
made.
Lest we forget was building this probe in the late 80s early 90s. CCD
technology was more costly than it is today.
Designing a custom chip would cost well over $1 000 000. Each chip cost
well over $1000 to make.
That is just for the sensor. You need to do the same thing at the same
price for the electronics and lens. If ESA paid less than $4 000 000
for the camera they got a bargain.

If you double the resolution then you quadruple the number of pixels
and the chance of a defect. You also quadruple the power consumption
and the weight.

This is all a moot point when compared with the one real factor: upload
speed. Huygens can only upload data at a fixed rate. Given the probe
has a fixed life span in which to transmit the data you have an
absolute amount of information you can upload. a certain amount of the
bandwidth is devoted to the other instruments. This leaves you with a
finite number of pixels you can transmit. There is no data redundancy
with the pictures so you can double that number. Divide this number by
the number of photos you want to take and you arrive at the maximum
resolution of your imager.

Ian Anderson
www.customopticalsystems.com

In article , Szaki wrote:
I would assume the last thing to design and build is the computers and
instruments in order to install the latest technology.

You would assume wrong.
When you want high reliability, the latest technology is exactly
the place that you don't go.
On the last servicing mission, the Hubble's internal computer was
upgraded to a 486. For most of it's life it's been run by a 386.
Radiation hardened, gold plated etc, but at heart a 386 comparable to my
first computer (1989 vintage).

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233

In article , George Dishman wrote:
The high gain comes at the cost of reduced beamwidth.
Huygens was falling through atmosphere and spinning.
It couldn't keep a high-gain antenna aligned on
Cassini.

Not the point. The point was that, *in mid-flight* a change in
the software on Galileo resulted, effectively, in an increase in the
bandwidth available to the instruments, and so allowed the original
science program to be carried out with only the lower bandwidth "low
gain" antenna.

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233

I notice something very interesting in the side view image after
touchdown (the upper frame of the triplets). If you select a low
numbered triplet (#171 for example) and look at the darker region in
the left of the center of the frame just above the light "boulder" and
compare with the same region in a high number triplet (#993 for
example) you can see what appears to be a significan change. Three
light colored objects show faintly in the high numbered image, but not
in the lower numbered one. I get the impression of looking through the
surface of a clear liquid at light objects forming on the bottom,
possibly localized freezing of the liquid. I get a strong impression
of movement in this region when I look at a sequence of the images as
well. Very interesting...

Clif Ashcraft

an mpeg has been mde of all these frames and shows movement
of something - at the esa sites they are passing this of as transmission
noise so far. Frankly who knows what it is. Nasa originally said
Hyugens had landed on something the consistency of packed snow?

But the mpeg/avi does show motion of something. However, unless
Im dreaming, the widescale shots show old impact craters - most small
ones? I hope Im not dreaming....

hsi



wrote:

I notice something very interesting in the side view image after
touchdown (the upper frame of the triplets). If you select a low
numbered triplet (#171 for example) and look at the darker region in
the left of the center of the frame just above the light "boulder" and
compare with the same region in a high number triplet (#993 for
example) you can see what appears to be a significan change. Three
light colored objects show faintly in the high numbered image, but not
in the lower numbered one. I get the impression of looking through the
surface of a clear liquid at light objects forming on the bottom,
possibly localized freezing of the liquid. I get a strong impression
of movement in this region when I look at a sequence of the images as
well. Very interesting...

Clif Ashcraft