Lunar Orbiter 4
   HOME

TheInfoList



OR:

Lunar Orbiter 4 was a robotic U.S.
spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, ...
, part of the Lunar Orbiter Program, designed to
orbit In celestial mechanics, an orbit 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 object or position in space such as ...
the Moon, after the three previous orbiters had completed the required needs for
Apollo Apollo, grc, Ἀπόλλωνος, Apóllōnos, label=genitive , ; , grc-dor, Ἀπέλλων, Apéllōn, ; grc, Ἀπείλων, Apeílōn, label=Arcadocypriot Greek, ; grc-aeo, Ἄπλουν, Áploun, la, Apollō, la, Apollinis, label= ...
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, and micrometeoroid impact data.


Mission Summary

The spacecraft was placed in a cislunar trajectory and injected into an elliptical near polar high lunar
orbit In celestial mechanics, an orbit 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 object or position in space such as ...
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 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 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 mission. A total of 419 high-resolution and 127 medium-resolution frames were acquired, covering 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 22–30 degrees W longitude.


See also

* Lunar Orbiter Image Recovery Project * Exploration of the Moon * Lunar Orbiter 1 * Lunar Orbiter 2 * Lunar Orbiter 3 * Lunar Orbiter 5 * List of artificial objects on the Moon


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