Posted by admin / on 30 November, 2010 / No Comments
Name given to the US programme to land men on the Moon and return them safely to Earth. The cost of the NATIONAL AERONAUTIC AND SPACE ADMINISTRATION’s (NASA’s) triumph in the Moon race with the Soviet Union was US$25 billion. At its peak, the programme employed some 500,000 people. The first public announcement of the intention of the USA to achieve the first manned landing on another world was made by President Kennedy in 1961. However, NASA was already preparing three series of robotic missions, namely RANGER, SURVEYOR and LUNAR ORBITER, to investigate the feasibility of manned missions and to search for suitable landing sites.
The Apollo spacecraft consisted of four units in two pairs: the Command and Service Module (CSM), together with the descent and ascent stages of the LUNAR MODULE (LM). The Command Module (CM) housed the astronauts during the journeys to the Moon and back. It remained attached to the Service Module (SM), which contained the rocket engines, fuel and electrical supply, until shortly before re-entering the Earth’s atmosphere. After achieving lunar orbit, the LM, containing two astronauts, undocked from the CSM, decelerated, and landed at the pre-selected location on the Moon’s surface. The third astronaut remained orbiting the Moon in the CSM. At the completion of extra-vehicular activities (EVAs) on the surface, the descent stage served as a launch platform for the ascent stage, which then redocked with the orbiting CSM. Following the transfer of the two astronauts, film cassettes and Moon rocks from the ascent stage to the CM, the former was jettisoned. It was usually targeted to impact the lunar surface, thereby providing a seismic signal of known energy to calibrate seismometers deployed on the surface.
Apollo 1 should have been the first Earth orbital test flight of the CM, but a fire in the CM during ground testing on 1967 January 27 killed astronauts Roger Chaffee (b.1935), Virgil Grissom (b.1926) and Edward White (b.1930) and prompted numerous design changes. This was followed by Apollo 4, 5 and 6, all unmanned flights to test the SATURN ROCKET.
The manned flights with three astronauts aboard – the Commander (CDR), the Lunar Module Pilot (LMP) and the Command Module Pilot (CMP) – began with Apollo 7. Originally 14 manned Apollo flights were planned but funding cuts later reduced this to 11. As confidence was gained, each mission gathered more scientific data than its predecessors. As durations of EVAs and distances covered increased, more comprehensive selections of rock and soil samples were obtained. More experiments were also deployed or conducted on the lunar surface, and the later orbiting CSMs obtained hundreds of high-resolution stereophotographs and other measurements of the surface.
Within the constraints dictated by spacecraft design and landing safety, the landing sites were chosen to give a reasonably representative selection of different surface types, as determined from earlier ground-based or spacecraft studies. In the case of Apollo 11, a nearequatorial site provided the simplest landing and redocking conditions, with a relatively smooth and level descent path and landing point. A location in Mare Tranquillitatis was chosen, not too far from the impact point of Ranger 8 and the landing point of Surveyor 5. Neil ARMSTRONG and ‘Buzz’ ALDRIN became the first men to step on the Moon. Apollo 12 was again targeted for an equatorial site on Oceanus Procellarum, very close to the earlier landing site of Surveyor 3. This enabled the astronauts to inspect and return spacecraft samples that had been exposed to the lunar environment for two and a half years. The ill-fated Apollo 13 was targeted for Fra Mauro, a near-equatorial site in the lunar highlands that was thought to be covered by ejecta from the impact event that produced the Imbrium Basin. Unfortunately, an oxygen tank in the SM exploded halfway to the Moon, disabling most of the spacecraft systems. Despite many hardships, the astronauts returned safely. Apollo 14 was targeted for the same landing location and was completely successful. The exploration by astronauts Alan SHEPARD and Stuart Roosa (1933– ) was aided by a wheeled trolley known as the Modular Equipment Transporter. The three remaining missions touched down well away from the equator and had the benefit of a batterypowered roving vehicle that widened the field of exploration. The Apollo 15 landing site combined a mare region (Palus Putredinis), a nearby sinuous valley (Hadley Rille) and very high mountains (the Apennines). Apollo 16 landed in a highlands area, on the so-called Cayley Formation – the loose material that fills in craters and covers the lower slopes here – but very close to the Descartes Formation, which was thought to represent possible highlands volcanism.
The choice of the Taurus-Littrow site for the final mission resulted largely from the Apollo 15 observations of small, dark-haloed craters, identified as possible volcanic vents, in the area. Additionally, the valley flor was one of the darkest mare surfaces on the Moon. Geologist-astronaut Harrison Schmitt (1935– ) was the only scientist to set foot on the Moon. The quantity of data resulting from the Apollo programme was overwhelming. The 380 kg of rock and soil samples have attracted particular attention, having been subjected to every kind of test and analysis imaginable. However, many of the stored samples have yet to be examined.
Another major archive is the collection of many thousands of photographs taken during the transit and orbital phases of the missions. In particular, the metric and panoramic cameras used on the last three missions produced high-resolution, wide-angle, stereoscopic coverage of about 20% of the lunar surface. Of the 16 or so other experiments conducted from orbit, ten were concerned with ‘remote sensing’, allowing a comparison with data from the landing sites. About 25 different types of experiment were carried out or deployed on the surface. These included seismometers, magnetometers and heat-flow experiments to investigate the subsurface structure and properties. Laser reflectors helped to refine the Moon–Earth distance.