The first leap in lunar observation was prompted by the invention of the telescope. Galileo Galilei made good use of this new instrument and observed mountains and craters on the Moon's surface.
The Cold War-inspired space race between the Soviet Union and the U.S. led to an acceleration of interest in the Moon. Unmanned probes, both flyby and impact/lander missions, were sent almost as soon as launcher capabilities would allow. The Soviet Union's Luna program was the first to reach the Moon with unmanned spacecraft. The first man-made object to escape Earth's gravity and pass near the Moon was Luna 1, the first man-made object to impact the lunar surface was Luna 2, and the first photographs of the normally occluded far side of the Moon were made by Luna 3, all in 1959. The first spacecraft to perform a successful lunar soft landing was Luna 9 and the first unmanned vehicle to orbit the Moon was Luna 10, both in 1966.[4] Moon samples have been brought back to Earth by three Luna missions (Luna 16, 20, and 24) and the Apollo missions 11 to 17 (except Apollo 13, which aborted its planned lunar landing).
The landing of the first humans on the Moon in 1969 is seen by many as the culmination of the space race.[77] Neil Armstrong became the first person to walk on the Moon as the commander of the American mission Apollo 11 by first setting foot on the Moon at 02:56 UTC on July 21, 1969. The American Moon landing and return was enabled by considerable technological advances, in domains such as ablation chemistry and atmospheric re-entry technology, in the early 1960s.
Scientific instrument packages were installed on the lunar surface during all of the Apollo missions. Long-lived ALSEP stations (Apollo lunar surface experiment package) were installed at the Apollo 12, 14, 15, 16, and 17 landing sites, whereas a temporary station referred to as EASEP (Early Apollo Scientific Experiments Package) was installed during the Apollo 11 mission. The ALSEP stations contained, among others, heat flow probes, seismometers, magnetometers, and corner-cube retroreflectors. Transmission of data to Earth was terminated on September 30, 1977 because of budgetary considerations.[78][79] Since the lunar laser ranging (LLR) corner-cube arrays are passive instruments, they are still being used. Ranging to the LLR stations is routinely performed from earth-based stations with an accuracy of a few centimetres, and data from this experiment are being used to place constraints on the size of the lunar core.[80]
37 years, 5 days have now passed since Eugene Cernan and Harrison Schmitt, as part of the mission Apollo 17, left the surface of the Moon on December 14, 1972 (Cernan being the last to enter the LM) and no one has set foot on it since.
From the mid-1960s to the mid-1970s, there were 65 instances of artificial objects reaching the Moon (both manned and robotic, with ten in 1971 alone), with the last being Luna 24 in 1976. Only 18 of these were controlled Moon landings, with nine completing a round trip from Earth and returning samples of Moon rocks. The Soviet Union then turned its primary attention to Venus and space stations, and the U.S. to Mars and beyond. In 1990, Japan orbited the Moon with the Hiten spacecraft, becoming the third country to place a spacecraft into lunar orbit. The spacecraft released a smaller probe, Hagormo, in lunar orbit, but the transmitter failed, thereby preventing further scientific use of the mission.
In 1994, the U.S. finally returned to the Moon, robotically at least, sending the Joint Defense Department/NASA spacecraft Clementine. This mission obtained the first near-global topographic map of the Moon, and the first global multispectral images of the lunar surface. This was followed by the Lunar Prospector mission in 1998. The neutron spectrometer on Lunar Prospector indicated the presence of excess hydrogen at the lunar poles, which is likely to have been caused by the presence of water ice in the upper few meters of the regolith within permanently shadowed craters. The European spacecraft Smart 1 was launched September 27, 2003 and was in lunar orbit from November 15, 2004 to September 3, 2006.
On January 14, 2004, U.S. President George W. Bush called for a plan to resume manned missions to the Moon by 2020 (see Vision for Space Exploration).[81] NASA is now planning for the construction of a permanent outpost at one of the lunar poles.[82] The People's Republic of China has expressed ambitious plans for exploring the Moon and has started the Chang'e program for lunar exploration, successfully launching its first spacecraft, Chang'e-1, on October 24, 2007. Like NASA, China hopes to land people on the Moon by 2020.[83] The U.S. launched the Lunar Reconnaissance Orbiter and the Lunar Crater Observation and Sensing Satellite on June 18, 2009 (the two missions were co-manifested). Russia also announced to resume its previously frozen project Luna-Glob, consisting of an unmanned lander and orbiter, which is slated to land in 2012.[84]
The Google Lunar X Prize, announced September 13, 2007, hopes to boost and encourage privately funded lunar exploration. The X Prize Foundation is offering anyone US$20 million who can land a robotic rover on the Moon and meet other specified criteria.
On September 14, 2007 the Japan Aerospace Exploration Agency launched SELENE, also known as Kaguya, a lunar orbiter which is fitted with a high-definition camera and two small satellites. The mission is expected to last one year.[85]
On October 22, 2008 India successfully launched the Chandrayaan I (a Sanskrit word literally meaning the 'Moon-craft') unmanned mission to the Moon and intends to launch several further unmanned missions. The country plans to launch Chandrayaan II in 2010 or 2011, which is slated to include a robotic lunar rover. India also has expressed its hope for a manned mission to the Moon by 2020.
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