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Topic: Lunar Laser Ranging Experiment

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	Lunar laser ranging experiment - Wikipedia, the free encyclopedia
		The ongoing Lunar Laser Ranging Experiment was first made possible by a lunar laser ranging retroreflector array planted on the Moon on July 21, 1969, by the crew of the Apollo 11.
		Lunar ranging also provides data useful for other experiments, including tests of general relativity designed by physicists such as Carrol Alley.
		Einstein's theory of gravity and the general theory of relativity predict the moon's orbit to within the accuracy of the laser ranging measurements.
	en.wikipedia.org /wiki/Lunar_Laser_Ranging_Experiment (433 words)

	Laser applications - Wikipedia, the free encyclopedia
		Laser beams are focused through large telescopes on Earth aimed toward the arrays, and the time taken for the beam to be reflected back to Earth measured to determine the distance between the Earth and Moon with high precision.
		This is a low-power laser pointer used to indicate a target for a precision-guided munition, typically launched from an aircraft.
		The first role envisioned for the laser in military applications was as a "death ray": a hand-held device that might replace the gun as a weapon for infantry, or a vehicle-mounted "laser cannon" able to destroy tanks, ships and aircraft.
	en.wikipedia.org /wiki/Laser_applications (1936 words)

	[No title] (Site not responding. Last check: 2007-10-13)
		Once the laser beam hits a reflector, scientists at the ranging observatories use extremely sensitive filtering and amplification equipment to detect the return signal, which is far too weak to be seen with the human eye.
		While the earliest ranges had accuracies of several meters (or several yards), continuing improvements in the lasers and the detection electronics have led to recent measurements that are accurate to about 3 centimeters (about 1 inch).
		From the ranging experiments, scientists know that the average distance between the centers of the Earth and the moon is 385,000 kilometers (239,000 miles), showing that modern lunar ranges have relative accuracies of better than one part in 10 billion.
	www2.jpl.nasa.gov /files/releases/lunlaser.txt (1004 words)

	Apollo Laser Ranging Experiments Yield Results (Site not responding. Last check: 2007-10-13)
		The first laser ranging retroreflector was positioned on the Moon in 1969 by the Apollo 11 astronauts.
		From the ranging experiments, scientists know that the average distance between the centers of the Earth and the Moon is 385,000 kilometers with an accuracy of better than one part in 10 billion.
		Ranging has also determined that the length of an Earth day has distinct small-scale variations of about one thousandth of a second over the course of a year, caused by the atmosphere, tides, and Earth's core.
	geophysics.ou.edu /solid_earth/readings/apollo_laser_ranging.html (607 words)

	JPL.NASA.GOV: News Releases
		The Lunar Laser Ranging experiment confirms that the Moon and Earth "fall toward" the Sun at the same rate, even though Earth has a large iron core below its rocky mantle, while the Moon is mostly rocky with a much smaller core.
		"Lunar laser ranging can conduct very accurate tests of gravity and fundamental physics," said Williams, who pointed out that small variations in gravity are difficult to study because the force is weak, unless very large masses are used.
		Lunar laser ranging measurements are helping future human and robotic missions to the Moon.
	www.jpl.nasa.gov /news/news.cfm?release=2005-039 (687 words)

	Lunar (Site not responding. Last check: 2007-10-13)
		Precise positions of the laser ranging observatories on Earth are slowly drifting as the crustal plates on Earth drift.
		Lunar ranging has greatly improved scientists' knowledge of the Moon's orbit, enough to permit accurate analyses of solar eclipses as far back as 1400 B.C. Investigators at JPL (J. Williams, et.
		The Apollo 11 and 14 laser reflector arrays are identical and consist of 100 fused silica corner cube reflectors, mounted in a 46 centimeter aluminum panel.
	ilrs.gsfc.nasa.gov /satellite_missions/list_of_satellites/lunar.html (657 words)

	Anthonares » Blog Archive » Bouncing Laser Beams Off of the Moon (Site not responding. Last check: 2007-10-13)
		Two of the science experiments, the Lunar Laser Ranging Experiment and the lunar seismometers (Passive Seismic Experiments), returned data long after the astronauts left.
		In the 35 years since the first LLRE reflector was deployed by the Apollo 11 astronauts, dozens of teams have used the laser reflectors to learn more about lunar geology and the evolution of the Earth/Moon system, as well as to conduct basic physics research.
		A laser beam that starts out from a telescope on earch at about 1 meter width slowly diverges and is blurred by the atmosphere until it is about 10 km wide on the surface of the moon.
	www.anthonares.net /2006/03/bouncing-laser-beams-off-of-the-moon.html (1768 words)

	Astromart News - Apollo 11 Experiment Still Going Strong after 35 Years
		Scientists from various institutions who analyze the data from the lunar laser ranging experiment have observed, among other things, that the Moon is moving away from the Earth and has a fluid core, and that Einstein's Theory of Relativity is accurate.
		The experiment consists of an instrument called the lunar laser ranging reflector, designed to reflect pulses of laser light fired from the Earth.
		To this end, a new lunar ranging instrument with significantly improved accuracy is being constructed at Apache Point Observatory in New Mexico by the University of California at San Diego and the University of Washington.
	www.astromart.com /news/news.asp?news_id=84 (853 words)

	Apollo 11 - Wikipedia, the free encyclopedia
		It was part of an experiment to test the properties of the lunar regolith.
		On July 20, 1969, while on the far side of the Moon, the lunar module, called Eagle, separated from the Command Module, named Columbia (Some internal NASA planning documents referred to the callsigns as Snowcone and Haystack; these were quietly changed before being announced to the press.
		Following this address, radio communications with the moon would have been cut off, the astronauts left alone to die, while a clergyman was to commend their souls to "the deepest of the deep" in the fashion of a burial at sea.
	en.wikipedia.org /wiki/Apollo_11 (3463 words)

	Apollo 14 Laser Ranging Retroreflector Experiment
		The reflected laser beam is also observed with the telescope, providing a measurement of the round-trip distance between Earth and the Moon.
		Laser beams are used because they remain tightly focused for large distances.
		These variations in rotation are related to the distribution of mass inside the Moon and imply the existence of a small core, with a radius of less than 350 kilometers, somewhat smaller than the limits imposed by the passive seismic and magnetometer experiments.
	www.lpi.usra.edu /expmoon/Apollo14/A14_Experiments_LRRR.html (388 words)

	Planetary 2 (Site not responding. Last check: 2007-10-13)
		By beaming laser pulses at the reflector from Earth, scientists have been able to determine their roundtrip travel time that gives the distance bet ween the two bodies at any time to an accuracy of about 3 centimeters.
		Laser ranging has also made possible a wealth of new infor mation about the dynamics and structure of the Moon.
		In addition, precise positions of the laser ra nging observatories on Earth are slowly drifting as the crustal plates on Earth drift.
	www.seds.org /nodes/NODEv4n2-4.2.html (481 words)

	Lunar Laser Ranging at McDonald
		The unique contributions already accomplished include a three orders-of-magnitude improvement in the accuracy of the lunar ephemeris, a several orders-of-magnitude improvement in the measurement of the variations in the Moon’s rotation, and the verification of the principal of equivalence for massive bodies with unprecedented accuracy.
		The lunar libration in longitude, with a period of only 2.9 yr, has a 69 yr beat with another term of similar period; a third mode of that libration has a 24 yr period with respect to the node; the dissipation term and the lunar obliquity have an 18.6 yr period.
		A new laser ranging station with LLR capability is currently being constructed to replace the present Matera artificial satellite only station in Italy.
	www.csr.utexas.edu /mlrs/dda.html (2881 words)

	ScienceDaily: Apollo 11 Experiment Continues To Return Valuable Data
		Scientists who analyze the data from the Lunar Laser Ranging Experiment have measured, among other things, that the Moon is moving away from the Earth and that the shape of the Earth is changing at an unprecedented accuracy level.
		Laser ranging has shown that the Moon is receding from the Earth at about 3.8 centimeters (1.5 inches) every year.
		Lunar Data Support Idea That Collision Split Earth, Moon (March 17, 1999) -- Analysis of data from NASA's Lunar Prospector spacecraft has confirmed that the Moon has a small core, supporting the theory that the bulk of the Moon was ripped away from the early Earth when an...
	www.sciencedaily.com /releases/1999/07/990720083540.htm (2193 words)

	History of Laser Ranging and MLRS
		The invention of the laser, with its precise wavelength and beam divergence characteristics, coupled with the technique of Q-Switching to produce laser pulse lengths on the order of only a few nanoseconds, caused a re-thinking of the artificial satellite photography experiment and ushered in the era of optical laser ranging.
		However, the spreading of a beam of outgoing laser light as it interacted with, and was reflected by, the moon's rough topography made ultra-precise distance determinations, as was done with artificial satellites, an impossibility.
		It was only in the late 1960's, with the birth of the NASA Apollo project for landing an astronaut safely on the moon, that the concept of laser ranging to a lunar surface corner retroreflector package became a reality.
	www.csr.utexas.edu /mlrs/history.html (1340 words)

	CNN - Apollo 11 experiment still returning results - July 21, 1999
		The laser beams bounce back anywhere from 2.3 to 2.6 seconds later and it is the tiny time differences that reveal the secrets of the moon's orbit and its movement over time.
		By multiplying the time the laser takes to return by the speed of light, researchers can calculate how far away the moon is at a particular point in time.
		He made a splash in the lunar science community in recent months with an analysis of lunar ranging data that showed the moon has a liquid core.
	www.cnn.com /TECH/space/9907/21/apollo.experiment (843 words)

	Abstract
		The major purpose of LLR experiments is to determine various facts about the relationship between the moon and the earth and to learn specific facts about the earth.
		In a LLR experiment, a very short pulse of laser light is fired through a telescope at one of the retro-reflectors.
		With this scenario, the LLR is a type of experiment virtually identical to the “Two Parallel Car Metaphor.” The line between the sun and Leo is represented by the path of the two parallel cars.
	pages.sbcglobal.net /webster.kehr/Chapters/Chapter100-LLR.htm (5636 words)

	Apollo ALSEP
		Until the Committee and Manned Space Flight Experiment Board agreed on assignment of priorities among the various lunar science experiments, this experiment was to be considered a contingency experiment to be carried on a "space available" basis.
		While the lunar module was on the moon, astronaut Worden completed 34 lunar orbits in the CSM operating scientific instrument module experiments and cameras to obtain data concerning the lunar surface and environment.
		An ultraviolet spectrometer measured lunar atmospheric density and composition; an infrared radiometer mapped the thermal characteristics of the moon; and a lunar sounder acquired data on the subsurface structure.
	www.astronautix.com /craft/apoalsep.htm (10797 words)

	Geodesy for the Layman
		LURE was designed to obtain extremely accurate measurements of the range from known locations on the surface of the earth to the lunar based retroreflectors and enable the improvement of our knowledge of the rotation of the earth and the moon about their center of mass and the moon's libration and motion about the earth.
		The satellite altimeter consists of a downward ranging radar which measures the time delay from the transmission to the reception of a pulse of energy.
		Inertial Navigation is the art and science of determining the position and velocity of a vehicle solely by means of sensing that vehicle's accelerations and performing the necessary integrations to determine the position and velocity on a real-time basis.
	www.floridageomatics.com /publications/gfl/chapter-seven.htm (1953 words)

	Apollo 11 Anniversary
		Lunar ranging, together with laser ranging to artificial Earth satellites, has revealed a small but constant change in the shape of the Earth.
		Lunar ranging has yielded an enormous improvement in our knowledge of the Moon's orbit, enough to permit accurate analyses of solar eclipses as far back as 1400 BC.
		Considering forthcoming the 30th anniversary of the first manned lunar mission and its great importance for cosmic exploration and all humankind, we should like to inform you that three minor planets discovered at the Klet Observatory in the Czech Republic were named in honor of the crew of Apollo 11 now.
	www.xs4all.nl /~carlkop/ap11.html (4556 words)

	Citebase - Lunar Laser Ranging Tests of the Equivalence Principle with the Earth and Moon (Site not responding. Last check: 2007-10-13)
		Authors: Williams, James G. Turyshev, Slava G. Boggs, Dale H. A primary objective of the Lunar Laser Ranging (LLR) experiment is to provide precise observations of the lunar orbit that contribute to a wide range of science investigations.
		Lunar laser ranging (LLR) is used to conduct high-precision measurements of ranges between an observatory on Earth and a laser retro-reflector on the lunar surface.
		Lunar Laser Ranging (LLR), which has been carried out for more than 35 years, is used to determine many parameters within the Earth-Moon system.
	citebase.eprints.org /cgi-bin/citations?id=oai:arXiv.org:gr-qc/0507083 (3459 words)

	Lunar laser ranging \| Cosmic Variance
		This experiment, called Lunar laser ranging, teaches us a lot about the Moon, but it also teaches us about gravity.
		The claim is that the DGP model predicts a tiny perturbation of the Moon’s orbit, too small to have yet been detected, but large enough to be within our reach if we improve the precision of existing laser ranging experiments.
		Let’s hope the Lunar ranging produces fuzzy results which shore up funding for extra dimensional theorists a bit longer.
	cosmicvariance.com /2006/03/24/lunar-radar-ranging (1447 words)

	The Apollo Laser Ranger Retroreflector Experiment
		Offhand, I would expect a powered radio transmitter to suffer from numerous, obvious disadvantages: Size of the component required to be sent to the moon, limited lifespan, and lower accuracy due to the longer wavelength.
		A guide telescope tracks something visible to keep the telescope used for the ranging measurement pointed at the right place even when that place is not visible.
		Therefore this experiment is of fundamental importance; however analysis even of this simple experiment is model dependent.
	www.physicsforums.com /showthread.php?p=772290 (1514 words)

	SPACE.com -- Lunar Love: New Calculation Shows Moon's Heart is All Mushy
		Researchers calculated the Love numbers from data gathered by the Lunar Laser Ranging Experiment, using retroreflectors left on the Moon's surface 30 years ago by U.S. and Russian missions.
		A laser pulse is fired from Earth to the Moon, bounced by a reflector and returned back to Earth.
		Scientists who analyze the data from the Lunar Laser Ranging Experiment have measured, among other things, that the Moon is
	www.space.com /scienceastronomy/solarsystem/lunar_love_020215.html (644 words)

	ScienceDaily: Moonbeams Shine On Einstein, Galileo And Newton (Site not responding. Last check: 2007-10-13)
		An Apollo astronaut is seen with a lunar reflector placed on the Moon -- one of three installed by Apollo Moon-walking astronauts.
		Moon's Heart Melted, Say Lunar Love Numbers (February 14, 2002) -- Love numbers -- measures of how much a planet's surface and interior move in response to the gravitational pull of nearby bodies -- may indicate that the Moon has something like a molten slush...
		Apollo 11 Experiment Continues To Return Valuable Data (July 20, 1999) -- An experiment left on the lunar surface 30 years ago by the Apollo 11 astronauts continues to return valuable data about the Earth-Moon system to scientific centers around the world, including...
	www.sciencedaily.com /releases/2005/03/050307095724.htm (1913 words)

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