Lunar Orbiter I was the first robotic spacecraft to capture high quality photographs of the Moon from orbit, transmitting to humankind its first detailed views of our satellite and photographs of stunning beauty.
Its mission was critical to reveal and map the previously unknown landscapes of our satellite. The Lunar Orbiters had an ingenious imaging system, which consisted of a dual lens camera, a film processing unit, a readout scanner, and a film handling apparatus. Both lenses, a 610mm narrow angle high-resolution (HR) lens and an 80mm wide-angle medium resolution (MR) lens, placed their frame exposures on a single roll of 70mm film. The axes of the two cameras were coincident so the area imaged in the high resolution frames was centered within the medium resolution frame areas.
The film was moved during exposure to compensate for the spacecraft velocity, which was estimated by an electric-optical sensor. The film was then processed, scanned, and the images transmitted back to Earth as “framelets” and then reassembled. A complete medium resolution frame usually required reassembly of 26 framelets while a complete high resolution frame required 86 framelets.
This medium resolution photograph (Lunar Orbiter frame I-25-M) was taken with the wide-angle 80mm lens from an altitude of 226 km. Latitude / longitude: 1.23°N, 76.16°E. The lunar equator is located between the 33-km crater Weierstrass (bottom center), the 31-km crater Van Vleck (bottom right), the 42-km crater Nobili (center left) and the 38-km crater Jenkins (center right).