How does Hubble Telescope capture it's images [and film imaging in space]?

[jmooney]

Where do you think the last of the Ektar 25 got to?

 

[Joe VanCleave]

The 486 processors in the Hubble are also radiation hardened, so they're not just off-the-shelf, consumer grade components. I think Intel ran a small, specialty Fab line of these products for government/military space applications.

~Joe

 

[Photo Engineer]

The government has intel and others make a whole series of specially hardened computers which are designed to withstand the environment of space and the EMP of nuclear war! The computer is essentially encased in a Faraday cage for additional protection over what is afforded by the chips' design.

PE

 

[Sirius Glass]

Well, it ain't analog...

"1990 ... In light of it's age" Age?, AGE?, AGE???? The thing's not old enough to drink beer. My father was reminiscing last night about the time he went to see Lenin speak in fomenting the Russian Revolution. And he's that's not _that_ old. 110, now you're getting old.

In any case the conceptual design started in 1969, with real design work beginning in '81. It carries multiple imaging systems, most of which have been upgraded over the years.

CCD's for imaging have been around since the early 70's.

However, space missions use only proven technology and tend to be many years behind the 'state of the art'. 1970's missions, like Voyager, used magnetic deflection vidicons and video tape recorders - the image was captured in near-real time and then sent back to earth very slowly. A very slow signal can be more easily picked from the noise of the eather, allowing the satellite to use a very low power transmitter.

By the time Hubble came around CCDs for space imaging were reasonably mature and in wide use in surveillance satellites. The Hubble has been described as a spy satellite that happens to be pointing the wrong way.

The wide-field camera of Hubble eye-candy fame is a CCD array imaging through a multitude of fine bandpass filters. The images are then 'false coloured' to translate the image for human eyesight.

Googling will reveal web sites with more Hubble information than you could ever want.

Nope. I worked on Voyage and programmed the science platform to take the Jupiter Rotation Movies and the Red Spot Movies. Voyager used CCDs.

Steve

 

[SilverGlow]

All sensors, CCD or CMOS are analog. Both types have been around since the 1960's.

 

[BetterSense]

No way are they analog. They have a discrete, fixed amount of photo sites on the sensor. If CMOS sensors are 'analog' then films are 'digital' because they work with individual electrons.

 

[Poohblah]

No way are they analog. They have a discrete, fixed amount of photo sites on the sensor. If CMOS sensors are 'analog' then films are 'digital' because they work with individual electrons.

A digital circuit is one that can only be on or off. This is the source of the ones and zeros that form the foundations of computer code. A modern computer is basically a big bunch of circuits that can only be on or off, and turning the right ones on and off in the correct order will produce an image on a screen, send data through the internet, etc.

Your standard household circuits, however, are analog - the circuit can be on or off, but it also has varying levels of "on" - for example, 110 volts can be run through the circuit, but so can 120 volts, etc. More voltage will make your lights brighter and your electric range hotter. So, varying levels.

CMOS and CCD sensors are analog because they produce output signals that are varying, not simply on or off. Each individual pixel will output a greater strength signal if more photons hit that sensor. So, therefore, just like the household circuits, there are varying levels of "on" for each pixel.

The "digital" in "digital camera" comes after the CMOS or CCD sensor produces signals. There is a chip in a digital camera that converts those analog signals into digital data for storage on the memory card.

Electronic sensors were used in TV cameras long before digital video cameras came about. The output of the chips was simply never converted to a digital signal.

 

[mgonzale]

I think SilverGlow was referring to the intensity level of a CCD or CMOS sensor being analog at the pixel site's output, with the digital part of it appearing downstream at the analog-to-digital converter.

 

[dbonamo]

What image capture technology does the Hubble Telescope use? The telescope was launched in 1990 so I am curious to know whether it captures images on film or digital (in light of it's age). If film, what sort? Just curious.

I think your question may have been answered, but as far as digital imaging is concern, the first patent for solid state imaging device was in 1979

Check out http://www.google.com/patents?vid=USPAT5298776

 

[JBrunner]

No way are they analog. They have a discrete, fixed amount of photo sites on the sensor. If CMOS sensors are 'analog' then films are 'digital' because they work with individual electrons.

Uh no. they are analog devices. You can hook them to an oscilloscope and see the waveform. I've done it. They do not read or output anything in an on/off or otherwise discreet state. Photo sites determine resolution, not signal. Also solid state is not synonymous with digital. As I stated before, I have cameras that are solid state- no tubes- but purely analog.

 

[Photo Engineer]

Well, digital -> analog converters look analog but actually move in steps based on bit count.

PE

 

[JBrunner]

Well, digital -> analog converters look analog but actually move in steps based on bit count.

PE

True, but how does that relate to a CCD?

 

[tim_walls]

No way are they analog. They have a discrete, fixed amount of photo sites on the sensor. If CMOS sensors are 'analog' then films are 'digital' because they work with individual electrons.

Huh? Any given piece of film has a discrete, fixed amount of photo sites on it as well. They're arranged a little more haphazardly than a CMOS/CCD sensor, of course.

The output of a CCD is indeed analogue. The output then goes through an analogue amplifier (the gain of which is adjusted to alter the sensitivity - i.e. change the ISO,) after which an analogue-to-digital converter quantizes and converts the output to a digital representation.

(If I recall correctly, what you actually get out of the CCD is an analogue waveform - i.e. you effectively drain the charge in each photosite (the charge collected being proportional to the light falling on the site) in turn* which results in a continuous waveform which is then amplified, and quantized by the D2A both in terms of the level and temporally (i.e. splitting the waveform up between the pixels.))


* I would assume there is some parallelism involved - i.e. the readout is 'multiplexed' in some way.

 

[tim_walls]

Uh no. they are analog devices. You can hook them to an oscilloscope and see the waveform. I've done it. They do not read or output anything in an on/off or otherwise discreet state. Photo sites determine resolution, not signal. Also solid state is not synonymous with digital. As I stated before, I have cameras that are solid state- no tubes- but purely analog.

Indeed; the invention of electronic imaging significantly pre-dates digital image processing - that nice Scottish chap Mr Baird was doing it in the 1920s after all .


(I have a plan to one of these days get round to reproducing a Baird style TV camera and television; a photo sensor, a lightbulb, a couple of LF lenses and a spinning disc or two and the job's a good'un as they say round these parts.)

 

[Photo Engineer]

Look guys, everything (as noted above) is digital on the atomic scale. A photon is detected or it is not, on or off! The difference is that in analog photography, 3 atoms (2 electrons) will cause an image to start to form. In 1 mole of silver there are 6.023 x 10^23 (that is 23 zeros) atoms of silver. In a square foot of film that is about 300 mg so the total amount of image forming centers may be 108/.300 / 3 * 6.023 x 10^23. That is a huge amount of "digital" dots. We cannot percieve the number of steps involved. To date, humanity can only make devices that count in 8, 16, 32, 64 and 128 bits or increments. Even the best devices count digitally in steps.

So, when we refer to digital, it is everywhere, but digital photography is limited by current technology and can't even draw a straight line. It draws jaggies instead. Analog photography draws jaggies but at the atomic level. We cant see them except as very fine grain at high magnification, but we see square pixels in digital images.

So, everything analog is digital but everything digital is not analog due to limitations in science. The more particles involved in a digital image, the more bits, the more we see an analog response.

PE

 

[cdholden]

For those in and around Nashville.
At the Frist this weekend:

Lecture: Imaging Space from Space
Saturday, January 10, 2:00 p.m.
Rechter Room, FREE


Dr. C. R. O’Dell, distinguished research professor of physics and astronomy at Vanderbilt University and founding project scientist for the Hubble Space Telescope at NASA, will lead a presentation concerning science imaging.

During its first fifty years NASA has imaged the Earth in ways never before possible, and has sent back pictures from distant planets. A sampling of images will be presented, including pictures of what the universe looked like in its infancy, with special emphasis on images from the Hubble Space Telescope.

 

[ic-racer]

One-hour minilab on the moon....

Found this interesting. I did not know it at the time, but the lunar Orbiter mission in the late 60's used an on-board processing system to develop film which was subsequently scanned (analog). The scanned pictures of the moon surface from the film were sent to the earth via radio communication. The images were recreated on a CRT screen on earth and photographed with a 35mm camera. Pretty fascinating system using Kodak film and Bimat film developer. http://www.lpi.usra.edu/resources/lunar_orbiter/book/introduction.shtml

 

[mikebarger]

This was done in space, or some movie studio

Mike

 

[EASmithV]

Awesome! I wonder how they kept it from leaking in null-G.

 

[edtbjon]

There is gravity on the moon, just no air (and thus no developer oxidation. )

//Björn

 

[Photo Engineer]

There was a longish thread about this just about a month ago.

I think you might profit from merging both.

PE

 

[FilmIs4Ever]

And it was *around* the moon, not on it. I have often said that "Moonrise Earth" taken by this mission is my favorite electronic image ;-)

 

[ben-s]

Here's the other thread: (there was a url link here which no longer exists)

A fascinating system...

 

[Photo Engineer]

Bimat evolved out of Grant Haists work on monobaths!

The most famous Earthrise over the moon was taken in color by the first crew to land on the moon. It was color transparency and printed from internegatives.

OOPS.... After checking, the Earthrise over the moon was first taken by the manned orbital mission around the moon. The manned landing mission took the full earth shot!

PE

 

[jim appleyard]

Rumor also has it that there a 'blad on the moon. If you can get your buns up there, it's yours, free!