用戶:Mildwall/月球軌道器1號

Lunar Orbiter 1

任務類型	Lunar orbiter
運營方	NASA
國際衛星標識符	1966-073A
衛星目錄序號	2394
任務時長	80天
航天器屬性
製造方	The Boeing Co.
發射質量	385.6公斤（850磅）
任務開始
發射日期	1966年8月10日 19:31 (1966-08-10UTC19:31) UTC
運載火箭	Atlas SLV-3 Agena-D
發射場	Cape Canaveral LC-13
任務結束
丟棄形式	Deorbited
離軌日期	1966年10月29日 (1966-10-30)
軌道參數
參照系	Selenocentric
半長軸	2,694 km（1,674 mi）
離心率	0.33
近selene點	189.1至40.5 km（117.5至25.2 mi）
遠selene點	1,866.8 km（1,160.0 mi）
傾角	12 degrees
週期	208.1 minutes
Lunar軌道器
入軌	August 14, 1966
撞擊點	6.35°N 160.72°E / 6.35; 160.72
軌道	577
Lunar Orbiter program

The Lunar Orbiter 1 robotic (unmanned) spacecraft, part of the 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 verification of safe landing sites for the Surveyor and Apollo missions. It was also equipped to collect selenodetic, radiation intensity, and micrometeoroid impact data.

The spacecraft was placed in an Earth parking orbit on August 10, 1966, at 19:31 UTC. The trans-lunar injection burn occurred at 20:04 UTC. The spacecraft experienced a temporary failure of the Canopus star tracker (probably due to stray sunlight) and overheating during its cruise to the Moon. 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 189.1乘1,866.8公里（117.5乘1,160.0英里） and had a period of 3 hours 37 minutes and an inclination of 12.2 degrees. On August 21, perilune was dropped to 58 km（36 mi） and on August 25 to 40.5 km（25.2 mi）. The spacecraft acquired photographic data from August 18 to 29, 1966, and readout occurred through September 14, 1966.

Spacecraft orbit and photographic coverage on the near side (left) and far side (right)

A total of 42 high-resolution and 187 medium-resolution frames were taken and transmitted to Earth covering over 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 the Earth ever from the distance of the Moon. Accurate data were acquired from all other experiments throughout the mission.

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) on the Moon's far side on October 29, 1966, on its 577th orbit. The early end of the nominal one-year mission was due to the small amount of remaining attitude control gas and other deteriorating conditions and was planned to avoid transmission interference with Lunar Orbiter 2.

Instruments

Lunar Photographic Studies	Evaluation of Apollo and Surveyor landing sites
Meteoroid Detectors	Detection of micrometeoroids in the lunar environment
Caesium Iodide Dosimeters	Radiation environment en route to and near the Moon
Selenodesy	Gravitational field and physical properties of the Moon

• 
  The first ever image of Earth from the distance of the Moon, August 23, 1966. This probe took a second such image on August 25.
• 
  Part of the photo to the left as reprocessed by LOIRP in 2008.

See also

• Lunar Orbiter Image Recovery Project
• Exploration of the Moon
• Lunar Orbiter 2
• Lunar Orbiter 3
• Lunar Orbiter 4
• Lunar Orbiter 5

External links

• Destination Moon: A History of the Lunar Orbiter Program (1976) by the NASA History Office
• Lunar Orbiter Photo Gallery - Mission 1 by the Lunar and Planetary Institute