Pictures of Earth from space had been taken before, by rockets in the 1940s, and satellites in the 1950s and 1960s. However, those pictures captured just parts of Earth, as opposed to a full-on view of the planet. In the summer of 1966, the United States was preparing to send the first humans to the moon. NASA needed high resolution pictures of the surface to make sure this is something they could land on and pick out landing sites. NASA could call upon off-the-shelf technology: Boeing and Eastman Kodak had previously developed a spacecraft with an onboard camera system for the Department of Defense.

The first spacecraft, Lunar Orbiter 1, left Earth on August 10, 1966. It was like a flying photography lab. The camera system itself took up at least a third of the spacecraft. The Lunar Orbiter camera contained dual lenses, taking photos at the same time. One lens took wide-angle images at medium resolution. A second lens took high-resolution images yielding details as small as 5 meters in size.  The camera had big honking reels of 70 mm film. The film would roll through, the camera would take pictures, and then move the exposed film to an automated developer. The automated film developer contained a mix of chemicals that would develop the film using a process similar to the method used by Polaroid cameras. An electron beam would then scan each developed image before transmitting the photos back to Earth using radio signals.

But at some point during the mission, NASA contemplated pointing the spacecraft’s camera at Earth. Repositioning the satellite was a high risk maneuver. But NASA decided to take the risk. So on August 23, the spacecraft successfully took a photo of an earthrise, the blue planet rising above the moon’s horizon. NASA took the image and created a poster of it which was given as gifts to everybody. Senators and congressmen would give it out as presents to constituents and visiting dignitaries.

Reference:

http://www.historyorb.com/day/august/23?p=2

http://www.space.com/12707-earth-photo-moon-nasa-lunar-orbiter-1-anniversary.html