EXPLORATION OF THE MOON

The Moon has been the target for unmanned and manned space missions throughout the second half of the 20th century. Driven by the "race for space" between the old Soviet Union and the United States, huge amounts of money and manpower were dedicated to task of making the first manned landing on the Moon.

More than 40 spacecraft have been sent to the Moon. Twelve men have walked on its surface and over 500 kg of Lunar samples have been returned to Earth.

The Soviet Luna 3 mission in 1959 provided the first glimpse of the far side of the Moon, but it was not until 1966 that Luna 9 achieved a soft landing and sent back the first pictures from the surface of the Moon. A few months later, in April 1966, that the US spacecraft, Surveyor 1 achieved a soft landing on the surface.

Before the first manned landing could take place, it was obviously necessary to prove that the crew could leave the Moon and be returned safely to Earth. The crew of Apollo 8 undertook the first manned trip to the Moon between 21 and 27 December 1968. This success was followed up in May 1969 when astronauts Stafford and Cernan descended in the Lunar Module to within 50,000 feet of the lunar surface. Finally, on 20 July 1969, Armstrong and Aldrin stepped out of the Lunar Module to be the first humans to walk on the surface of the Moon.

The Apollo manned landing program continued until December 1972 when Apollo 17 crew stayed on the surface for 75 hours.

The Apollo missions demonstrated that it was possible for humans to visit other bodies in space, however the cost of manned exploration is difficult to justify when the alternative, of using unmanned spacecraft and robots, is cheaper, safer and in some ways more effective.

Some height data had been collected during the Apollo orbits, but the first global topographical map of the Moon was generated from altimetry data collected by Clementine, a lightweight spacecraft that orbited the Moon between 6 February and 5 May 1994. Clementine's official name: Deep Space Probe Science Experiment, carried a laser altimeter which mapped the surface with a resolution of 125 – 250 metres. Clementine's other main instruments were a set of multispectral cameras able to image the surface in various wavelengths. The images from these are used to generate maps of the distribution of minerals across the surface and allow investigators to study how the surface composition relates to geological structure. Clementine data was also used to look for water.

Between 6 January 1998 and August 1999, Lunar Prospector flew in polar orbit at an average height of 100 kilometres. Lunar Prospector’s mission was to continue Clementine’s search for evidence of water on the Moon and collect magnetic field and gravity data. The viability of a permanent manned Moon base depends on the ability to extract water from the surface. Prospector's neutron spectrometer produced strong evidence that water ice lies in the polar areas that are permanently in shadow. In August 1999, Lunar Prospector, running low on fuel, was deliberately crashed into a crater in the hope of providing further evidence of the existence of water on the Moon, if water could be detected in the impact plume. Although no water was detected in the plume, researchers were greatly encouraged by Prospector's mapping results.

Ongoing and future missions include Europe's SMART-1, and Selene, managed by the Japanese Space Agency (ISAS).