The Lunar Laser Ranging Experiment from the Apollo 11 mission

The ongoing Lunar Laser Ranging Experiment measures the distance between the Earth and the Moon using laser ranging. Lasers on Earth are aimed at retroreflectors previously planted on the Moon and the time delay for the reflected light to return is determined. The distance has been measured repeatedly over a period of more than 35 years. Download high resolution version (904x913, 314 KB)The Lunar Laser Ranging Experiment from the Apollo 11 mission. ... Download high resolution version (904x913, 314 KB)The Lunar Laser Ranging Experiment from the Apollo 11 mission. ... In astronomy, a lunar distance ( LD ) is a measurement of the distance from the Earth to the Moon. ... This article is about Earth as a planet. ... This article is about Earths moon. ... A FASOR used at the Starfire Optical Range for LIDAR and laser guide star experiments is tuned to the sodium D2a line and used to excite sodium atoms in the upper atmosphere. ... For other uses, see Laser (disambiguation). ... Retroreflectors are clearly visible in a pair of bicycle shoes. ...

The experiment was first made possible by a retroreflector array installed on July 21, 1969, by the crew of the Apollo 11. Two more retroreflector arrays left by the Apollo 14 and Apollo 15 missions have contributed to the experiment. is the 202nd day of the year (203rd in leap years) in the Gregorian calendar. ... Also: 1969 (number) 1969 (movie) 1969 (Stargate SG-1) episode. ... This article covers the Apollo 11 mission itself. ... Apollo 14 was the eighth manned mission in the Apollo program and the third mission to land on the Moon. ... Apollo 15 was the ninth manned mission in the Apollo program and the fourth mission to land on the Moon. ...

The unmanned Soviet Lunokhod 1 and Lunokhod 2 rovers carried smaller arrays. Reflected signals were initially received from Lunokhod 1, but no return signals have been detected since 1971, at least in part due to some uncertainty in its location on the Moon. Lunokhod 2's array continues to return signals to Earth.[1] Lunokhod series Soviet Moon exploration robot vehicle A panorama shot from Lunokhod 1 A photo from Lunokhod 1 showing the Luna 17 lander The tracks of Lunokhod showing the little wheel in the center that was used for odometry. ... Lunokhod series Soviet Moon exploration robot vehicle Lunokhod 2 was the second of two unmanned lunar rovers landed on the Moon by the Soviet Union as part of the Lunokhod program. ...

Apollo 14 Lunar Ranging Retro Reflector (LRRR)

The Apollo 15 array is three times the size of the arrays left by the two earlier Apollo missions. Its size made it the target of three-quarters of the sample measurements taken in the first 25 years of the experiment. Improvements in technology since then have resulted in greater use of the smaller arrays, by sites such as the McDonald Observatory and the OCA Laser-Lune telemetry station affiliated with the Côte d'Azur Observatory. Image File history File links Size of this preview: 601 × 600 pixelsFull resolution‎ (904 × 902 pixels, file size: 207 KB, MIME type: image/jpeg)Apollo 14s LRRR. File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 601 × 600 pixelsFull resolution‎ (904 × 902 pixels, file size: 207 KB, MIME type: image/jpeg)Apollo 14s LRRR. File historyClick on a date/time to view the file as it appeared at that time. ... McDonald Observatorys 2. ... Telemetry is a technology that allows the remote measurement and reporting of information of interest to the system designer or operator. ... The Côte dAzur Observatory (in French: Observatoire de la Côte dAzur) originated in 1988 with the merger of two observatories: Nice Observatory The CERGA (Centre dÉtudes et de Recherches Géodynamiques et Astronomiques) External links Côte dAzur Observatory official website (English version) ...

As of 2002 work is progressing on increasing the accuracy of the Earth-Moon measurements to near millimeter accuracy. Also see: 2002 (number). ...

Apollo 15 LRRR

Some of the findings of this long-term experiment are: Image File history File links Size of this preview: 596 × 599 pixelsFull resolution‎ (904 × 909 pixels, file size: 183 KB, MIME type: image/jpeg)Apollo 15s LRRR. File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 596 × 599 pixelsFull resolution‎ (904 × 909 pixels, file size: 183 KB, MIME type: image/jpeg)Apollo 15s LRRR. File historyClick on a date/time to view the file as it appeared at that time. ...

• The moon is spiraling away from Earth at a rate of 3.8 cm per year. ^[1]
• The moon probably has a liquid core of about 20% of the Moon's radius. ^[2]
• The universal force of gravity is very stable. The experiments have put an upper limit of the change in Newton's gravitational constant G of less than 1 part in 100,000,000,000 since 1969. ^[2]
• Einstein's theory of gravity (the general theory of relativity) predicts the moon's orbit to within the accuracy of the laser ranging measurements. ^[2]

The undeniable presence of the reflectors on the Moon's surface has been used to refute claims that the Apollo landings were faked. Gravity redirects here. ... Sir Isaac Newton FRS (4 January 1643 – 31 March 1727) [ OS: 25 December 1642 – 20 March 1727][1] was an English physicist, mathematician, astronomer, natural philosopher, and alchemist. ... According to the law of universal gravitation, the attractive force between two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them. ... “Einstein” redirects here. ... For a less technical and generally accessible introduction to the topic, see Introduction to general relativity. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... Buzz Aldrin and Neil Armstrong in NASAs training mockup of the Moon and lander module. ...

Lunokhod 1 – the small structure on the left is the retroreflector.

Image File history File links Lunokhod_1. ... Image File history File links Lunokhod_1. ...

See also

• Lunar distance (astronomy)
• LIDAR
• Carroll Alley, principal investigator of Apollo's reflector experiment
• Lunokhod programme
• Apache Point Observatory Lunar Laser-ranging Operation
• Apollo Lunar Surface Experiments Package
• Independent evidence for Apollo Moon landings

In astronomy, a lunar distance ( LD ) is a measurement of the distance from the Earth to the Moon. ... A FASOR used at the Starfire Optical Range for LIDAR and laser guide star experiments is tuned to the sodium D2a line and used to excite sodium atoms in the upper atmosphere. ... Carrol Alley is an American physicist. ... Lunokhod series Soviet Moon exploration robot vehicle A panorama shot from Lunokhod 1 Lunokhod (Russian for Moon walker) 1 and 2 were a pair of unmanned lunar rovers landed on the Moon by the Soviet Union. ... The Apache Point Observatory Lunar Laser-ranging Operation, or APOLLO, is a project at the Apache Point Observatory in New Mexico. ... ALSEP of the Apollo 16 mission The Apollo Lunar Surface Experiments Package (ALSEP) comprised a set of scientific instruments placed by the astronauts at the landing site of each of the five Apollo missions to land on the Moon following Apollo 11 (Apollos 12, 14, 15, 16, and 17). ... Apollo 12 astronaut Pete Conrad with the unmanned Surveyor 3 lander. ...

References

1. ^ NASA 1994 article "MEASURING THE MOON'S DISTANCE"
2. ^ ^{a b c} J.W.J Dickey, "Lunar Geophysics, Geodesy, and Dynamics", 2002. (PDF link below)

External links and sources

• Lunar Geophysics, Geodesy, and Dynamics by James Williams Jean Dickey in 13th International Workshop on Laser Ranging, October 7-11, 2002, Washington, D. C.
• Apollo 15 Laser Ranging Retroreflector Experiment
• History of Laser Ranging
• Lunar Retroreflectors History and Position
• Station de Télémétrie Laser-Lune in Grasse, France
• 1994 article on "Measuring the Moon's Distance"
• 2002 article about "UW researcher plans project to pin down moon's distance from Earth"
• NASA: What Neil & Buzz Left on the Moon
• CNN: Apollo 11 Experiment Still Returning Results after 30 Years
• JPL: Apollo 11 Experiment Still Going Strong after 35 Years