Lunar Orbiter 3
NASA’s Lunar Orbiter 3 was the final mission to photograph potential Apollo landing sites. A glitch prevented the spacecraft from relaying back all of its images, but it did meet all mission objectives. One of the images showed the Surveyor 2 lander on the lunar surface.
Mission objective
launch vehicle
Launch
Landing
Lunar Orbiter 3
The Lunar Orbiter 3 spacecraft was designed primarily to photograph areas of the lunar surface for confirmation of safe landing sites for the Surveyor and Apollo missions.
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Key Dates
Feb.5, 1967: Launch
Feb. 8, 1967: Arrived in lunar orbit
Feb. 15, 1967: Photographic mission began
Oct. 9, 1967: Spacecraft intentionally crashed onto lunar surface
In Depth: Lunar Orbiter 3
Lunar Orbiter 3 was NASA’s final Lunar Orbiter mission to study potential Apollo landing sites, although its mission focused on site confirmation rather than site search. For the mission, the spacecraft’s orbital inclination was increased to 21 degrees to ensure photography both north and south of the lunar equator.
Building on the stereo photography taken by Lunar Orbiter 2, the third mission was focused on making two “footprints” of the same area on two successive orbits. Lunar Orbiter 3 was also designed to obtain precision trajectory information for defining the lunar gravitational field, to measure micrometeoroid flux, and to measure radiation dosage levels around the Moon.
The spacecraft arrived in lunar orbit after a 9-minute 2.5-second engine burn on Feb. 8, 1967, after a course correction. Initial orbital parameters were 131 × 1,120 miles (210.2 × 1,801.9 kilometers) at a 20.93-degree inclination.
About four days later, the spacecraft entered its operational 34 × 1,148-mile (55 × 1,847-kilometer) orbit at a 20.9-degree inclination. At the time, Lunar Orbiter 2 was still in operation around the Moon, thus providing key experience for NASA’s ability to track and communicate with two simultaneous spacecraft at the Moon.
Lunar Orbiter 3 began its photographic mission Feb. 15, 1967. The spacecraft exposed 211 (out of a possible 212) frames of pictures by the time that imaging concluded Feb. 23. Soon, the spacecraft began to “read out” the images to the ground, but this activity suddenly stopped March 4 due to a problem with the film advance mechanism in the readout section of the imaging system. As such, only 182 images were returned and 72 others were never read out to the ground.
Despite the glitch, Lunar Orbiter 3 wholly fulfilled its original mission objectives, returning images of 6 million square miles (15.5 million square kilometers) of the Moon’s near side and 251,000 square miles (650,000 square kilometers) of the far side. One of the images showed the Surveyor 2 lander on the lunar surface.
On Aug. 30, 1967, ground controllers commanded the vehicle to circularize its orbit to 99 miles (160 kilometers) in order to simulate an Apollo trajectory.
Later, on Oct. 9, 1967, the probe was intentionally crashed onto the lunar surface at 14 degrees 36 minutes north latitude and 91 degrees 42 minutes west longitude.
The photographs from the first three Lunar Orbiters allowed NASA scientists to pick eight preliminary landing sites for Apollo by early April 1967—including site 2 in the Sea of Tranquility where Apollo 11 would land and site 5 in the Ocean of Storms where Apollo 12 (and also Surveyor 3) would disembark.
Key Source
Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.
| Objective(s) | Lunar Orbit |
| Spacecraft | LO-C (Spacecraft 6) |
| Spacecraft Mass | 850 pounds (385.6 kilograms) |
| Mission Design and Management | NASA / LaRC |
| Launch Vehicle | Atlas Agena D (Atlas Agena D no. 20 / Atlas D no. 5803 / Agena D no. AD128/6632) |
| Launch Date and Time | Feb. 5, 1967 / 01:17:01 UT |
| Launch Site | Cape Canaveral, Fla. / Launch Complex 13 |
| Scientific Instruments | 1. Imaging System 2. Micrometeoroid Detectors 3. Radiation Dosimeters |
Lunar Orbiter 3 Image Catalog
Lunar Orbiter III is known as the site-confirmation mission. It was tasked to re-photograph 12 potential landing sites identified by LO I and II with a comprehensive array of vertical, oblique, and forward wide-angle stereo and convergent telephoto stereo photography. These data led to a down-select to eight candidate landing sites for early Apollo missions. This mission also targeted secondary sites of scientific interest on the lunar farside and at higher latitudes on the lunar nearside. The spacecraft was launched February 5, 1967. Between February 15 and 23 it produced 211 photographs during 54 orbits. Approximately 75% of the photographs were transmitted to Earth, but the remaining images were lost.
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