I recently stumbled upon an image of crescent Earth taken during Apollo 4, on November 9, 1967. It was a beautiful shot, but not one I had ever seen, despite having trawled through the Apollo archives many times.

Apollo 4 was the first test flight of the Saturn V rocket. It sent an uncrewed command module to high Earth orbit, where an engine burn sent the spacecraft hurtling back towards the ocean at speeds comparable to returning from the Moon. The entire mission lasted just eight hours. What I didn't know, until seeing that crescent Earth image, was that there was a camera in the command module window, timed to take pictures from an altitude of about 18,000 kilometers during the final orbit. In total, 755 pictures were taken, and 712 had some or all of Earth in the frame. The mission imagery report says they are the first color film photos taken from that altitude.

You can find the low-res image thumbnails online, thanks to the Lunar and Planetary Institute in Houston. But curiously, I couldn't find any of the high-res images except a couple cropped excerpts scattered around the Internet. This is in stark contrast to the crewed Apollo missions, which have been exhaustively cataloged.

I got in touch with David Bigwood, who works at the LPI Regional Planetary Image Facility, one of several such facilities around the world that host physical and digital space mission imagery. David located the high-res versions, scanned from film. Unfortunately, the file set was huge, consuming a whopping 1.3 terabytes of disk space. David was kind enough to compress the TIFF files into smaller, 14000-by-16000-pixel JPGs, and send me copies. It took him more than a week, though I think (hope) that most of that was computer processing time, not manual labor. Thanks, David!

Even compressed, the images are beautiful. Here's one with Earth right in the middle of the frame: