Lecture 4 Page 1 Overview
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Exploring the Solar System Lecture 4: Exploration of the Moon Professor Paul Sellin Department of Physics University of Surrey Guildford UK Page 1 Paul Sellin Lecture 4 Page 1 Overview Exploration of the Moon: Moon probes: Luna, Ranger and Lunar Orbiter programmes Surveyor: the first controlled landing on the Moon Apollo: manned spaceflight to the Moon Samples from the Moon – lunar geology Page 2 Paul Sellin Lecture 4 Page 2 Exploration of the Moon Lunar missions covered the period 1959 to the 1990s: Luna 1, 2, 3 sent in 1959 by the Soviet Union to approach the Moon Project Ranger started in 1960 by the US, transmitting close-up views of the Moon’s surface before crashing into the Moon Lunar Orbiter programme: 5 spacecraft from 1966-1967 competed a high resolution photographic survey of the Moon’s surface, showing features as small as 1m. This data was used to select possible landing sights for the Apollo landings Surveyor programme: 5 unmanned spacecraft landed on the Moon during 1966-1968. Data from these spacecraft proved that the Moon’s surface was solid, and not a thick layer of dust Apollo consisted of 6 manned landings on the Moon – Apollo 11 in July 1969 followed by Apollo 14-17, landing in progressively more challenging terrain Unmanned Soviet spacecraft landed on the Moon from 1966 – 1976, with Luna 9 landing 4 months after the US Surveyor 1 in 1966. In the 1970s Luna spacecraft landed vehicles which explored the surface, and returned rock samples to Earth Clementine spent 2 months observing the Moon in 1994, carrying various UV/Vis/IR imaging cameras which revealed the atomic composition of large areas of the Moon’s surface Page 3 Paul Sellin Lecture 4 Page 3 Ranger programme The Ranger project of the 1960s was the first U.S. effort to launch probes directly toward the Moon. Ranger spacecraft were equipped with 6 TV cameras which transmitted close-up view of the Moon before they crash-landed into its surface. A variety of difficulties plagued the first several attempted missions in this series, but the Rangers 7-9 were a complete success Ranger 1: Launched 23 August 1961 Failed to leave Earth parking orbit Ranger 2: Launched 18 November 1961 Failed to leave Earth parking orbit Ranger 3: Launched 26 January 1962 Earth contact lost, missed the Moon by ~36,800 km Ranger 4: Launched 23 April 1962 Sequencer failed, impacted the Moon 26 April 1962 Ranger 5: Launched 18 October 1962 Earth contact lost, missed the Moon by 725 km Ranger 6: Launched 30 January 1964 Cameras failed, impacted the Moon 2 February 1964 Ranger 9 http://www.jpl.nasa.gov/missions/past/ranger.htmlPage 4 Paul Sellin Ranger 1 was launched from Cape Canaveral, Florida, on August 23, 1961, followed by the launch of Ranger 2 on November 18 of that year. In both cases, the Agena B rocket engine failed to restart and both spacecraft reentered Earth's atmosphere a short time later. Ranger 3 was launched January 26, 1962, but an inaccuracy put it off course and it missed the Moon. Ranger 4 had a perfect launch on April 23 of that year, but the spacecraft was completely disabled. The project team tracked the seismometer capsule to impact just out of sight on the far side of the Moon, validating the spacecraft's communications and navigation system. Ranger 5 missed the Moon following its launch on October 18, 1962, and was disabled. Ranger 6 was launched January 30, 1964, and had a flawless flight culminating in impact as planned on the Moon; its television system, however, was disabled by an in-flight accident and could take no pictures. The next three Rangers, with a redesigned television, were completely successful. Ranger 7 was launched July 28, 1964, and sent more than 4,300 pictures on its way down to target in a lunar plain, soon named Mare Cognitum, south of the crater Copernicus. Following launch on February 17, 1965, Ranger 8 successfully completed its mission with a planned crash-landing in Mare Tranquillitatis, where the Apollo 11 astronauts would land 4-1/2 years later. Ranger 8 garnered more than 7,300 images. Ranger 9 was launched March 21, 1965, and impacted the Moon in the 90- kilometer-diameter (75-mile) crater Alphonsus, sending back more than 5,800 images. Lecture 4 Page 4 Ranger images (1) The last two pictures taken by Ranger 9 before impact onto the lunar surface on the floor of Alphonsus crater. The top image was taken at a distance of 600m 0.25s before impact. The frame is about 70 m across. The lower frame includes most of the area on the left of the Ranger 9 view of crater Alphonsus upper image and was taken 3 minutes before impact, at a from 1.2km 4.5s prior to impact. distance of 442km The image is approximately 50 meters across. http://www.jpl.nasa.gov/missions/past/ranger.htmlPage 5 Paul Sellin Ranger 9 image of Alphonsus crater (diameter 108 km) from a distance of 442 km, taken about 3 minutes before impact in the upper right portion of the crater. At left is the northeastern edge of Mare Nubium. The crater adjacent to Alphonsus at the bottom is the 39 km diameter Alpetragius. Davy crater is at upper left. North is at 12:30. Ranger 9 impacted the Moon on 24 March 1965 at 14:08:20 UT. Lecture 4 Page 5 Ranger images (2) Ranger 9 image from 2500 km showing Ranger 9 image taken 54 seconds before impact, at Ptolemaeus, Alphonsus, and Albategnius 136km. The raised area at lower center is the central craters. peak of Alphonsus crater floor. Page 6 Paul Sellin (left) Ptolemaeus is the large (164 diameter) flat-floored crater at the top. Alphonsus, diameter 108 km, is at lower left and the 114 km Albategnius crater is at lower right. The terminator runs through the lower corner. Ranger 9 impacted in Alphonsus crater 18.5 minutes after this image was taken. North is at 12:30 (right) This image was taken from a distance of 136 km. The impact point of Ranger 9 is to the right of the central reticle, about 60% of the way from the central reticle to the edge of the frame. The image is 60 km across and north is at 12:30. Lecture 4 Page 6 Lunar Orbiter 5 Lunar Orbiters sent back a total of 2180 high resolution and 882 medium resolution images of the Moon’s surface, covering 99.5% of the Moon’s surface with resolution down to 1m. The micrometeoroid experiments recorded 22 impacts showing the average micrometeoroid flux near the Moon was about two orders of magnitude greater than in interplanetary space but slightly less than the near Earth environment. The radiation experiments confirmed that the design of Apollo hardware would protect the astronauts from average and greater-than-average short term exposure to solar particle events. Page 7 Paul Sellin http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1967-075A Lunar Orbiter 5, the last of the Lunar Orbiter series, was designed to take additional Apollo and Surveyor landing site photography and to take broad survey images of unphotographed parts of the Moon's far side. It was also equipped to collect radiation intensity, and micrometeoroid impact data and was used to evaluate the Manned Space Flight Network tracking stations and Apollo Orbit Determination Program. The spacecraft was placed in a cislunar trajectory and on 5 August 1967 was injected into an elliptical near polar lunar orbit 194.5 km x 6023 km with an inclination of 85 degrees and a period of 8 hours 30 minutes. On 9 August the orbit was lowered to a 99 km x 1499 km, 3 hour 11 minute period. The photographic portion of the mission ended on 18 August. The spacecraft acquired photographic data from August 6 to 18, 1967, and readout occurred until August 27, 1967. A total of 633 high resolution and 211 medium resolution frames at resolution down to 2 meters were acquired, bringing the cumulative photographic coverage by the 5 Lunar Orbiters to 99% of the Moon's surface. Accurate data were acquired from all other experiments throughout the mission. The spacecraft was tracked until it impacted the lunar surface on command on January 31, 1968. The use of Lunar Orbiters for tracking to evaluate the Manned Space Flight Network tracking stations and Apollo Orbit Determination Program was successful, with three Lunar Orbiters (2, 3, and 5) being tracked simultaneously from August to October 1967. The Lunar Orbiters were all eventually commanded to crash on the Moon before their attitude control gas ran out so they would not present navigational or communications hazards to later Apollo flights. Lecture 4 Page 7 Marius crater Lunar Orbiter 5 image of the plateau west-northwest of Marius crater on the Moon. Note the two sinuous rilles which cut across a ridge at the center of the image. Also visible are volcanic domes and cones. The round "cobra-head" feature at the center left is roughly 2.5 km in diameter. The image is 80 km across and north is at 2:30 All Lunar Orbiter images from: http://nssdc.gsfc.nasa.gov/imgcat Page 8 Paul Sellin Lecture 4 Page 8 Aristarchus crater Lunar Orbiter 5 view of Aristarchus crater on the Moon. The crater is approximately 40 km in diameter, and 3.6 km in depth from rim to floor. Note the hummocky ejecta blanket surrounding the crater and the concentric and radial valleys along the crater walls, resulting from mass wasting.