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Lunar Orbiter 4 was a robotic U.S.
After initial photography on May 11, 1967 problems started occurring with the camera's thermal door, which was not responding well to commands to open and close. Fear that the door could become stuck in the closed position covering the camera lenses led to a decision to leave the door open. This required extra
Image:Atlas Agena launching Lunar Orbiter 4.jpg, Launch of ''Lunar Orbiter 4'' from an
spacecraft
A spacecraft is a vehicle that is designed spaceflight, to fly and operate in outer space. Spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth observation, Weather s ...
, part of the 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 ...
, designed to orbit
In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...
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 ...
, after the three previous orbiters had completed the required needs for 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 ...
mapping and site selection. It was given a more general objective, to "perform a broad systematic photographic survey of lunar surface features in order to increase the scientific knowledge of their nature, origin, and processes, and to serve as a basis for selecting sites for more detailed scientific study by subsequent orbital and landing missions". It was also equipped to collect selenodetic, radiation intensity
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 ...
, 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
The spacecraft was placed in a cislunar trajectory and injected into an elliptical near polar high lunarorbit
In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...
for data acquisition. The orbit was with an inclination of 85.5 degrees and a period of 12 hours.
After initial photography on May 11, 1967 problems started occurring with the camera's thermal door, which was not responding well to commands to open and close. Fear that the door could become stuck in the closed position covering the camera lenses led to a decision to leave the door open. This required extra attitude control
Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, ...
maneuvers on each orbit to prevent light leakage into the camera which would ruin the film. On May 13 it was discovered that light leakage was damaging some of the film, and the door was tested and partially closed. Some fogging of the lens was then suspected due to condensation
Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor ...
resulting from the lower temperatures. Changes in the attitude raised the temperature of the camera and generally eliminated the fogging. Continuing problems with the readout drive mechanism starting and stopping beginning on May 20 resulted in a decision to terminate the photographic portion of the mission on May 26. Despite problems with the readout drive the entire film was read and transmitted. The spacecraft acquired photographic data from May 11 to 26, 1967, and readout occurred through June 1, 1967. The orbit was then lowered to gather orbital data for the upcoming Lunar Orbiter 5
Lunar Orbiter 5, the last of the "Lunar Orbiter series", was designed to take additional Project Apollo, Apollo and Surveyor program, Surveyor landing site photography and to take broad survey images of unphotographed parts of the Moon's far sid ...
mission.
A total of 419 high-resolution and 127 medium-resolution frames were acquired, which covered 99% of the Moon's near side at resolutions from . Accurate data was acquired from all other experiments throughout the mission. Radiation data showed increased dosages due to solar particle events producing low energy protons. The spacecraft was used for tracking until it struck the lunar surface due to the natural decay of the orbit no later than October 31, 1967, between 22 and 30 degrees W longitude.
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 on May 4, 1967
Image:Lunar Orbiter 4 - FRAME 4079-H3 - DPLA - 659e5b52f0a881469578ef382cb20eda.jpg, Keldysh on May 16, 1967 ()
Image:Lunar Orbiter 4 - FRAME 4122-H1 - DPLA - ebcecfb905e2cc0301d8e53cac0d9d0b.jpg, Timocharis
Timocharis of Alexandria ( or Τιμοχάρης, ''gen.'' Τιμοχάρους; c. 320–260 BC) was a Greek astronomer and philosopher. Likely born in Alexandria, he was a contemporary of Euclid.
Work
What little is known about Timocharis comes ...
crater on May 19, 1967 ()
Image:Wichmann LO-IV-137H LTVT.JPG, Wichmann crater (lower right) and Wichman R (arc of ridges) on May 21, 1967
Image:Stadius crater (Lunar Orbiter 4).jpg, Image of Stadius crater
Image:Mare Orientale (Lunar Orbiter 4).png, Mare Orientale
Mare Orientale (Latin ''orientāle'', the "eastern sea") is a lunar mare. It is located on the western border of the near side and far side of the Moon, and is difficult to see from an Earthbound perspective. Images from spacecraft have revea ...
on the far side of the Moon, May 1967
Image:Lunar Orbiter 4151 h1 (cropped).jpg, ''Lunar Orbiter 4'' image of Aristarchus crater (top) and Vallis Schröteri, May 1967
Image:Planitia Descensus NASA Lunar Orbiter iv 162 h1.jpg, Planitia Descensus, the landing site of Luna 9
Luna 9 (Луна-9), internal designation Ye-6 No.13, was an uncrewed space mission of the Soviet Union's Luna programme. On 3 February 1966, the Luna 9 spacecraft became the first spacecraft to achieve a soft landing on the Moon and return ima ...
See also
*Lunar Orbiter Image Recovery Project
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, ...
* Exploration of the Moon
The physical exploration of the Moon began when ''Luna 2'', a space probe launched by the Soviet Union, made a deliberate impact on the surface of the Moon on 14 September, 1959. Prior to that the only available means of lunar exploration had ...
* List of artificial objects on the Moon
This is a partial list of artificial materials left on the Moon, many during the missions of the Apollo program. The table below does not include lesser Apollo mission artificial objects, such as a hammer and other tools, Laser Ranging Retroflect ...
* List of missions to the Moon
Missions to the Moon have been numerous and include some of the earliest space missions, conducting exploration of the Moon since 1959.
The first partially successful lunar mission was Luna 1 (January 1959), the first probe to leave Earth ...
** Lunar Orbiter 1
The 1966 Lunar Orbiter 1 robotic spacecraft mission, part of NASA's Lunar Orbiter program, was the first American spacecraft to orbit the Moon. It was designed primarily to photograph smooth areas of the lunar surface for selection and verific ...
** 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 ...
** Lunar Orbiter 3
The Lunar Orbiter 3 was a spacecraft launched by NASA in 1967 as part of the Lunar Orbiter program, Lunar Orbiter Program. It was designed primarily to photograph areas of the Moon, lunar surface for confirmation of safe landing sites for the S ...
** Lunar Orbiter 5
Lunar Orbiter 5, the last of the "Lunar Orbiter series", was designed to take additional Project Apollo, Apollo and Surveyor program, Surveyor landing site photography and to take broad survey images of unphotographed parts of the Moon's far sid ...
References
{{Use American English, date=January 2014 4 Spacecraft launched in 1967 Spacecraft that orbited the Moon Spacecraft that impacted the Moon 1967 on the Moon