The moon photos of the Apollo era were developed in space. Here's how.

Before Neil Armstrong could take his first historic step on the moon, NASA needed to know exactly where the Apollo 11 spacecraft could land safely. In the early 1960s, maps of the lunar surface of humanity were based on photographs taken of the Earth and some early US and Soviet satellites, none of which could capture the scale and detail needed to landing free of rocks and dangerous craters.

That's why the space agency launched its Lunar Orbiter program, a fleet of five almost identical van-type satellites, sent in 1966 and 1967 to map the moon. Lunar Orbiter 3, which took pictures from February 15 to 23, 1967, confirmed the safe landing sites of the Apollo program, making some of the last pictures of the moon before humans put their boots on lunar soil .

In the pre-digital era, sending photos of space to Earth was not an occasional task. But thanks to precise engineering, and a very secret reconnaissance technology, the Lunar Orbiters provided NASA engineers and scientists with the necessary images to make Apollo 's landing possible.

The lunar orbiters were not the first moon-focused photo-focused spacecraft, but they were unique because of the equipment they carried.

"They basically borrowed spy cameras from the Department of Defense from their satellite program," says David Williams, acting head of NASA's space science coordinated archives. At the time, the US Department of Defense used similar cameras in the CORONA program, known to the public as Discoverer, to take satellite photos of the Soviet Union.

Each Lunar Orbiter had two cameras, one with a high resolution lens and one with a medium resolution. Rather than 35 millimeter standard films, the satellites used a size of 70 millimeters, the same size as today used to make IMAX films.

A few hundred kilometers above the surface of the moon, the Lunar Orbiters captured entities as wide as three feet wide. But the use of movies in the space is hurting a major hurdle.

"Once on the moon, you can take all the photos as you see fit, but you have no way to bring the film back to Earth to develop it," says Williams. "So they had to design a system to develop the film aboard the spaceship."

The development of a film usually requires rinsing the negatives in a series of liquid chemicals, which would cause considerable damage to the interior of a satellite in microgravity. Instead, the Lunar Orbiters used the Kodak BIMAT transfer processing system, which had been classified by the CIA until 2001 because it had been created primarily for recognition.

The film had to be moved precisely first from the storage reel to the lens, then into a storage area at the moment the remaining photographs were taken, and finally at the development stage, where a layer of gelatin infused with chemicals was pressed against the film. The tasks were performed in aluminum bins the size of a watermelon. The exhaustion of a single film engine, as in Lunar Orbiter 3 after capturing a few hundred views, was enough to threaten the success of a mission.

When you look inside a Lunar Orbiter satellite, "it's an interesting kind of analysis of Cold War relations," says Matt Shindell, curator at the Smithsonian National Air and Space Museum. "You see all the Eastman Kodak material there … and you see the camera designed by our intelligence agencies, and then you have all the NASA equipment."

To return their photos to Earth, the CORONA program dropped space films into capsules equipped with heat shields for fall protection, steering and stabilization thrusters and parachutes to slow down their fall. . The rescue plane had been built to hang a capsule in the air with his parachute, but in case of failure, a team of helicopters was recovering it in the water. However, NASA has instead developed a system for sending photographs by radio.

On the lunar orbiters, the film was moved to a scanner that shone and recorded the brightness levels of each tiny section measured. These numbers were then sent by radio signal to NASA's deep-space communication centers in Spain, Australia and the United States, where the measurements were received on magnetic tape. The image processors could then use the numbers to recreate the film shows on Earth and stick the tapes together to develop extremely detailed photographs.

"You can take a magnifying glass and look at them very closely and see all that detail. it's really amazing, "says Williams. "Considering it was the mid-sixties, it was truly an incredible feat."

Some of the resulting images, like the famous Lunar Orbiter 1 photograph of the Earth behind the moon's horizon, show the vertical lines of the reconstruction process. In spite of contrary theories, it is unlikely that NASA got involved in image quality before publishing its photos to the public.

"They were not afraid to publish what they thought were good representative images, so that people would know that the US space program was capable of doing such things," says Shindell. Throughout the mission, images of Lunar Orbiter have been published in newspapers and magazines around the world.

"Even if it was the space race and the most competitive in the world," says Shindell, "there was always a kind of atmosphere of this type that was created for the good of not only the countries that practice it, but also for the sake of science around the world. " world."