This project was the subject of a WWDC lunch session in 2009 I believe. One of the best I have seen.
There was so much more content in the WWDC presentation, I wished they had filmed lunch sessions at the time:
- It was not only moon orbiter pictures but also stuff from the apollo missions
- The analog pictures were actually transmitted over radio with an analog process (converting black and white in frequencies)
- This signal was then digitized and used to recreate images on the ground
- What they use (at least what they showed 4 yers ago) is the raw sound files that were recorded. Of course this is much better than the recreated on the ground images because you are one step closer to the source.
- They first had to find a way to read those files on tapes. They actually called this presentation "data archeology" because of this. Had to find tape readers, get them back to work, etc.
- Using DSP processing they were able to significantly improve the quality of the reconstruction process, dealing with mechanical problems on the space side (like the film were moving on a roll which speed was not perfectly constant)
- One of the most interesting result was an image reconstructed in 2000s compared to the original image. Turned out to be one of the first picture of earth poles (and ice cap). Extremely useful today.
1:30, Austin Epps "The quality of the analogue process used during the 1960s significantly degraded the actual quality of the images that were taken onboard the spacecraft, they didn't have the computing power necessary to do this as an all digital process back then whereas right now, you can basically do what was impossible to do in 1964/5 on a $2000 computer"
2:36 Dennis Wingo "I really want this material to be to be conserved, part of scientific validity is to be able to go back to the original sources."
Nice catch. I am a 'vicarious lunatic' and look forward to the publication of this material.
Please, anyone with budgetary power, pause for thought about the preservation of raw data for the future