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Comment by LiamPa | Hacker News Reader

> After their use, the images were locked away from the public, as at the time they would have revealed the superior technology of the USA’s spy satellite cameras, which the orbiters cameras were designed from. Instead the images from that time were grainy and low resolution, made to be so by NASA.

Brilliant!

It states they used 70mm film which according to google is used for motion pictures, I assume a custom camera?

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I would guess a development of Corona, the earliest spy satellites. Those earliest spy satellites were essentially disposable cameras. When full they dropped the film to be caught in mid air by the air force.

(A fascinating wiki hole - you may be gone some time) :)

https://en.wikipedia.org/wiki/Corona_(satellite)

CORONA Digital Atlas of the Middle East: http://corona.cast.uark.edu/atlas#zoom=5&center=4700000,3600...

I'm not certain about the film used for the Lunar Orbiter probes, but the cameras that were used by the Apollo astronauts used 70mm film, rather than the 60mm 120 format that was standard for the Hasselblad cameras they used.

The size of the frame is the same, but 70mm film is wider because it has sprocket holes that 120 format film lacks.

I would imagine that for the Lunar Orbiter probes they did use a custom camera, and didn't just bolt on an off the shelf camera.

According to this article, Walt Schirra's Hasselblad was the first one in space and after that they were used exclusively for some years. I guess before that they were custom.

https://www.hasselblad.com/history/hasselblad-in-space/

The first camera that was brought into space for the Mercury program was a remarkably unremarkable Ansco Autoset rangefinder manufactured by Minolta [1] that was picked up at a drug store, which went up with John Glenn.

Of course, Hasselblad didn't put that in their marketing material. Nasa then moved to using Nikon cameras around the Spacelab era, and still uses Nikons to this day.

[1] https://history.nasa.gov/apollo_photo.html

So far NASA used Nikon because Nikon didn't use fluorite elements, unlike Canon. However now Nikon started to use fluorite elements as well. I wonder what will happen in the future.

Why would they avoid fluorite elements?

Fluorite glass is more sensitive to shock and vibration compared to regular optical glasses. Iirc some people actually managed to disintegrate lens elements here on earth, without even hurling them into space.

I guess that makes sense but is NASA actually shipping off the shelf DSLR lenses to space anyway? I guess for astronauts’ personal devices, whatever. But for actual scientific instruments, I’d expect NASA is bidding out custom contracts that can easily specify how much shock tolerance the cameras must withstand.

What I find amazing is a film camera in a hard vacuum. I could be wrong but two things. Designing mechanical things that work in a hard vacuum is difficult. I'm assuming bad things would happen to film in a vacuum. So assuming they were sealed under argon or nitrogen.

Nope.

"Lubricants had to be chosen with utmost care because of the risk that conventional lubricants could boil off in vacuum and condense all over the optical surfaces of the lens."

http://www.mir.com.my/rb/photography/hardwares/moon/2.htm

I do remember the hand held camera's weren't sealed. So film and components needed to be redesigned to work. For instance special anti static film. And mechanical parts made of glass to prevent cold welding.

But with Apollo they could take the film back and develop it normally. The orbiters developed film in space and then scanned it. I tried looking and found nothing, but the orbiter camera's developed film using a semi-dry processed using damp ribbons that seem similar to a old typewriter ribbon.

Mechnical things largely work the same. What you do have to pay attention to is that you can't have stuff like flywheels that rely on air to slow them down.

Otherwise, a film camera would work the same in vacuum, even if it had some electric components.

For the film itself, I don't think you need anything special, there is nothing on the material that would boil off under vacuum to my knowledge.

The difficult parts are really heat because unlike in air, any heat you gain is difficult to get rid off again since there is no air to transport it away. So if you do have some electrics in your camera they can easily overheat if not designed for vacuum operation.

"Largely" is rather vague, and you left out things one does have to worry about. Quoting https://en.wikipedia.org/wiki/Vacuum_cementing :

> Vacuum cementing or vacuum welding is the natural process of solidifying small objects in a hard vacuum. ...

> This effect was reported to be a problem with the first American and Soviet satellites, as small moving parts would seize together. ...

> In 2009 the European Space Agency published a peer-reviewed paper detailing why cold welding is a significant issue that spacecraft designers need to carefully consider.

Regarding specifically plastic, which might be used for the film, see https://en.wikipedia.org/wiki/Corrosion_in_space : "Many plastics are considerably sensitive to atomic oxygen and ionizing radiation."

That link also points out the "material fatigue caused by cyclical heating and cooling and associated thermal expansion mechanical stresses."

As an example of cold welding. The Galileo spacecraft wasn't able to deploy its high-gain antenna because the pins that held it in place got stuck. There was graphite lubricant to prevent that but it was shaken out while it was being transported to the launch site.

Also in the early 90's saw a price list for (3M's) two part silicone products. One product was $25,000 a gallon. Application was for space craft windows. Turns out regular silicon will out gas and fog windows under hard vacuum.

All the above has lead me to have a lot of respect for the engineers that made this stuff work. Ditto because every time I've had a materials problem it's been a trail of tears.

They weren't sealed, but they were modified for space.

You can't use liquid lubricants in space, so they had to use solid lubrication or none at all.

Also, as film gets wound through the camera, it generates static electricity. Usually, this gets wicked away by the atmosphere. However, there is no atmosphere in space, so they had to have a special metal plate to dissipate the built up electrical charge.

The film itself was normal photographic film, although a special emulsion made specifically for NASA.

For the Moon landings, the film was not normal photographic film, it was a special thin base film mounted in special backs that allowed for 160/200 frames per back, instead of the 12 exposures you get with normal 120 film on a regular Hasselback back. Not sure what they used for the scouting missions.

Weirdly enough they used color slide film for the Moon missions. I never understood why. Color slide film has much less dynamic range compared to color negative film (5-6 stops vs. 12-14 stops, depending on the specific films) and it is much more difficult to expose for correctly (in fact, most pictures taken on the Moon are severely under/overexposed). One explanations I heard was that there was no color reference on the moon, so they didn't know how to print from negative film, but that doesn't make any sense to me. The Moon is very gray, and they could have taken a color chart with them...

I had a Mamiya 645 which had 120 and also 220 backs. The 220 roll had double the number of exposures, this was enabled by a thinner film and less backing paper from what I recall. I recently sold it all and was told the 220 backs were worthless now, I presume the film is no longer / not widely available.

120 film is widely available. I don't know why 220 film was not that popular.

Waste and the associated expense thereof, for one. Especially for professional use - there is an average waste of half of the last roll of film on every shoot, and that means 8-12 wasted frames on 220 versus 4-6 on 120. For the consumer side, a very large percentage of cameras used a window on the backing paper for frame counts, something that would be disastrous for 220. And for anything that used a pressure plate rather than just film tension to maintain film flatness, you'd need to have an adjustable plate (many cameras didn't have that).

Thanks for the extra info. I vaguely remember the frame counters, we had a Rolli twin lens reflex too in the early days and ISTR that had the window.

What I meant was that it wasn't some super exotic photographic film, printed on an unobtanium base.

It was standard acetate film with a gelatin emulsion.

Aside from the special Ektachrome, they also took black and white film magazines with them. The colour slide magazines held 160 exposures and the black and white magazines held 200 exposures.

I believe the reason they used slide film was that the quality of colour negative film wasn't so good back in the 60's. A lot of the shots they took on the moon were bracketed for exposure, so they took 3 images of the same subject, but with different exposures.

On the note of Apollo mission photography, there is an archive of a huge amount of photos taken on the Apollo missions on Flickr here: https://www.flickr.com/photos/projectapolloarchive/albums

70mm is also a "normal Hasselblad back"; it served much the same function as bulk film backs for 35mm cameras. There were, of course, issues that kept them from being the default backs for most photographers: the (relatively) small image size, which made for grainier images; the large capacity was actually a negative for most casual and professional uses (if anything was even close to time-sensitive, you'd wind up wasting a lot of film), and the size and weight of the back itself compared to the more typical A12/A24 backs.

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