Back in the 1960’s, leading up to the first landings on the moon, the not-so-imaginatively named Lunar Orbiter series of spacecraft collected reams of images of the moon. All 5 Lunar Orbiter spacecraft were successful, eventually resulting in photography of 99% of the lunar surface to a resolution of 60 meters or better.
The process used to produce these images was a bit convoluted, courtesy of limitations of the technology of the times. The lunar surface was imaged using a special film camera that moved the film during the each exposure in order to compensate for the spacecraft’s motion. Then the film was developed and scanned onboard, and the scan transmitted back to Earth via an analog (vs. digital) signal. On the ground, the analog signal was then recorded on analog magnetic tape, as well as turned back into an image on film. At the time the images were first produced, these film strips were turned into photomosaics by hand, and produced images that were tremendously useful for landing site selection. But these original images were marred by artifacts introduced in the production process — in particular, stripes from hand-joined photographed.
Now fast forward a few decades…
With talk of a return to the moon butting up against fiscal constraints, NASA spawned the Lunar Orbiter Digitization Project in 2000 — its goal, to produce a global mosaic of the Moon from Lunar Orbiter film strips. And over a few years, this is exactly what they did.
But another set of engineers had a different idea. The analog magnetic tapes used to record the original signals from the Lunar Orbiters were (nearly miraculously) still available, thanks to a few stubborn individuals that refused to junk them. Working mostly in their spare time, they managed to cobble together a working tape player from parts of a few defunct ones — eventually getting NASA funding as the Lunar Orbiter Image Recovery Project (LOIRP). The images they’re now producing have twice the resolution and 4 times the dynamic range of the originals released back in the 1960’s — and it’s only cost taxpayers about $250,000 to date, a far cry from NASA’s much higher projections.
Here’s a quick (2:06) AP video on their work:
If you’d like to read more about the Lunar Orbiters, and the LOIRP, here are some handy links:
Lunar Orbiter Program at the Lunar & Planetary Institute