The 1966 Lunar Orbiter 1

robotic spacecraft Uncrewed spacecraft or robotic spacecraft are spacecraft without people on board. Uncrewed spacecraft may have varying levels of autonomy from human input, such as remote control, or remote guidance. They may also be autonomous, in which t ...

mission, part of

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

Lunar Orbiter program The Lunar Orbiter program was a series of five uncrewed lunar orbiter missions launched by the United States in 1966 and 1967. Intended to help select Apollo landing sites by mapping the Moon's surface, they provided the first photographs from ...

, was the first American spacecraft to orbit the Moon. It was designed primarily to photograph smooth areas of the

lunar Lunar most commonly means "of or relating to the Moon". Lunar may also refer to: Arts and entertainment * ''Lunar'' (series), a series of video games * "Lunar" (song), by David Guetta * "Lunar", a song by Priestess from the 2009 album ''Prior t ...

surface for selection and verification of safe landing sites for the

Surveyor Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. These points are usually on the ...

and

Apollo Apollo is one of the Twelve Olympians, Olympian deities in Ancient Greek religion, ancient Greek and Ancient Roman religion, Roman religion and Greek mythology, Greek and Roman mythology. Apollo has been recognized as a god of archery, mu ...

missions. It was also equipped to collect selenodetic,

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...

intensity, and

micrometeoroid A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through Earth's atmosphere and reaches Earth's surface. The term "micrometeoro ...

impact data.

Mission summary

Mission controllers injected the spacecraft into a

parking orbit A parking orbit is a temporary orbit used during the launch of a spacecraft. A launch vehicle follows a trajectory to the parking orbit, then coasts for a while, then engines fire again to enter the final desired trajectory. An alternative trajec ...

around

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on August 10, 1966, at 19:31 UTC. The

trans-lunar injection A trans-lunar injection (TLI) is a propulsive maneuver, which is used to send a spacecraft to the Moon. Typical lunar transfer trajectories approximate Hohmann transfers, although low-energy transfers have also been used in some cases, as with ...

burn occurred at 20:04 UTC. The spacecraft experienced a temporary failure of the

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star tracker (probably due to stray sunlight) and overheating during its cruise to the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

. The star tracker problem was resolved by navigating using the Moon as a reference, and the overheating was abated by orienting the spacecraft 36 degrees off-Sun to lower the temperature. Lunar Orbiter 1 was injected into an elliptical near-equatorial lunar orbit 92.1 hours after launch. The initial orbit was and had a period of 3 hours 37 minutes and an inclination of 12.2 degrees. On August 21,

perilune An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides pert ...

was dropped to and on August 25 to . The spacecraft acquired photographic data from August 18 to 29, 1966, and readout occurred through September 14, 1966. Lunar Orbiter 1 coverage

A total of 42 high-resolution and 187 medium-resolution frames were taken and transmitted to Earth covering more than 5 million square kilometers of the Moon's surface, accomplishing about 75% of the intended mission, although a number of the early high-resolution photos showed severe smearing. It also took the first two pictures of Earth from the Moon. Accurate data were acquired from all other experiments throughout the mission. While not disclosed until after the end of the

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, the imaging system on the Lunar Orbiter spacecraft were the same

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cameras developed by the National Reconnaissance Office (NRO) for the

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reconnaissance satellites. NASA extended the camera innovation further by developing the film onboard the spacecraft and then scanning the photos for transmission via a video signal. Orbit tracking showed a slight "pear-shape" of the Moon based on the gravity field, and no micrometeorite impacts were detected. The spacecraft was tracked until it impacted the lunar surface on command at 7 degrees north latitude, 161 degrees east longitude (

selenographic coordinates The selenographic coordinate system is used to refer to locations on the surface of Earth's moon. Any position on the lunar surface can be referenced by specifying two numerical values, which are comparable to the latitude and longitude of Earth ...

) on the Moon's far side on October 29, 1966, on its 577th orbit. The early end of the nominal one-year mission resulted from a shortage of remaining attitude control gas and other deteriorating conditions and was planned to avoid transmission interference with

Lunar Orbiter 2 The 1966 Lunar Orbiter 2 robotic spacecraft mission, part of the Lunar Orbiter program, Lunar Orbiter Program, was designed primarily to photograph smooth areas of the lunar surface for selection and verification of safe landing sites for the S ...

. Image:Lunar Orbiter I Launch - GPN-2000-001898.jpg, Launch of ''Lunar Orbiter 1'' from an

Atlas-Agena The Atlas-Agena was an American expendable launch system derived from the SM-65 Atlas missile. It was a member of the Atlas (rocket family), Atlas family of rockets, and was launched 109 times between 1960 and 1978. It was used to launch the first ...

rocket in August 10, 1966 Image:First View of Earth from Moon.jpg, The first image of Earth from the distance of the Moon, August 23, 1966. The image (frame 1102; image 102 of Lunar Orbiter 1) consists of three parts h1-h3. Since its original publication its raw analog data has been used to digitally produce the image in higher resolution and clarity (see below). This probe took a second such image on August 25. Image:First View of Earth from Moon - reprocessed.png, Part of the photo to the left as reprocessed by

LOIRP The Lunar Orbiter Image Recovery Project (LOIRP) was a project to digitize the original analog data tapes from the five Lunar Orbiter spacecraft that were sent to the Moon in 1966 and 1967; it was funded by NASA, SkyCorp, SpaceRef Interactive, ...

in 2008. Image:First View of Earth from Moon - reprocessed wide.jpg, Full reprocessed image from 2008. Image:Lunar Orbiter 1 - FRAME 1102-M - DPLA - 7a4fb8fc80531e2e033f91b4ce3bc1b2.jpg, Wide angle frame 1102-m image Image:Earthrise 23 Aug 1966.jpg, Central 1102-h image.

References

{{NASA space program 1 Spacecraft launched in 1966 Spacecraft that orbited the Moon Spacecraft that impacted the Moon 1966 on the Moon

Mission summary

See also

References