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Mirrors for measuring Earth–Moon distance From Wikipedia, the free encyclopedia
Retroreflectors are devices which reflect light back to its source. Six were left at six sites on the Moon by three crews of the Apollo program, two by remote landers of the Lunokhod program, and one by the Chandrayaan program.[1] Lunar reflectors have enabled precise measurement of the Earth–Moon distance since 1969 using lunar laser ranging.[2]
Several unsuccessful attempts to land retroreflectors on the lunar surface have been made, and several future attempts are planned.
Operator | Mission | Name | Date | Location | Coordinates | Size | Status | Comment |
---|---|---|---|---|---|---|---|---|
NASA | Apollo 11 | LRRR | 21 July 1969 | Mare Tranquillitatis | 0.6734°N 23.4731°E[3] | 46×46 cm[4] | Operational | [5] |
Soviet Union | Luna 17 | Lunokhod 1 | 17 November 1970 | Mare Imbrium | 38.3152°N 35.0080°W[3] | 44×19 cm[1] | Operational | Rediscovered in 2010[6][7][8][9] |
NASA | Apollo 14 | LRRR | 31 January 1971 | Fra Mauro formation | 3.6442°S 17.4786°W[3] | 46×46 cm | Operational | [10] |
NASA | Apollo 15 | LRRR | 31 July 1971 | Hadley–Apennine | 26.1334°N 3.6285°E[3] | 105×65 cm | Operational | [11] |
Soviet Union | Luna 21 | Lunokhod 2 | 15 January 1973 | Le Monnier crater | 25.8323°N 30.9221°E[3] | 44×19 cm[1] | Operational | [12][13] |
ISRO | Chandrayaan-3 | Vikram | 23 August 2023 | Statio Shiv Shakti | 69.367621°S 32.348126°E | 5.11 cm diameter[14] | Operational | [15][16][17][18] |
Operator | Mission | Name | Date | Location | Coordinates | Status | Comment |
---|---|---|---|---|---|---|---|
SpaceIL, IAI | Beresheet | Beresheet | 11 April 2019 | Mare Serenitatis | 32.5956°N 19.3496°E | Crashed | [19][20][21] |
ISRO | Chandrayaan-2 | Vikram | 6 September 2019 | 70.8810°S 22.7840°E | Crashed | [22][23] | |
Moon Express | Lunar Scout | MoonLIGHT on MX-1E | July 2020 | Malapert Mountain | 84.9°S 12.9°E | Cancelled | [24][25] |
Astrobotic | Mission One | LRA on Peregrine | May 2023 | Lacus Mortis | Aborted, controlled re-entry |
[26] | |
Roscosmos | Luna 25 | Luna 25 | August 2023 | Boguslawsky (crater) | Crashed | [27][28][29] | |
Intuitive Machines | IM-1 | LRA on Nova-C IM-1 | February 2024 | Malapert (crater) | Failed | [30][26] |
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