Apollo 8, the second manned spaceflight mission flown in the United States Apollo space program, was launched on December 21, 1968, became the first manned spacecraft to leave low Earth orbit, reach the Moon, orbit it, return. The three-astronaut crew—Frank Borman, James Lovell, William Anders—were the first humans to fly to the Moon, to witness and photograph an Earthrise, to escape the gravity of a celestial body. Apollo 8 was the third flight and the first crewed launch of the Saturn V rocket and was the first human spaceflight from the Kennedy Space Center, located adjacent to Cape Canaveral Air Force Station in Florida. Planned as the second crewed Apollo Lunar Module and command module test, to be flown in an elliptical medium Earth orbit in early 1969, the mission profile was changed in August 1968 to a more ambitious command-module-only lunar orbital flight to be flown in December, as the lunar module was not yet ready to make its first flight. Astronaut Jim McDivitt's crew, who were training to fly the first lunar module flight in low Earth orbit, became the crew for the Apollo 9 mission, Borman's crew were moved to the Apollo 8 mission.
This left Borman's crew with two to three months' less training and preparation time than planned, replaced the planned lunar module training with translunar navigation training. Apollo 8 took 68 hours to travel the distance to the Moon; the crew orbited the Moon ten times over the course of twenty hours, during which they made a Christmas Eve television broadcast in which they read the first ten verses from the Book of Genesis. At the time, the broadcast was the most watched TV program ever. Apollo 8's successful mission paved the way for Apollo 11 to fulfill U. S. president John F. Kennedy's goal of landing a man on the Moon before the end of the 1960s; the Apollo 8 astronauts returned to Earth on December 27, 1968, when their spacecraft splashed down in the northern Pacific Ocean. The crew members were named Time magazine's "Men of the Year" for 1968 upon their return. In the late 1950s and early 1960s, the United States was engaged in the Cold War, a geopolitical rivalry with the Soviet Union.
On October 4, 1957, the Soviet Union launched the first artificial satellite. This unexpected success stoked imaginations around the world, it not only demonstrated that the Soviet Union had the capability to deliver nuclear weapons over intercontinental distances, it challenged American claims of military and technological superiority. The launch triggered the Space Race. President John F. Kennedy believed that not only was it in the national interest of the United States to be superior to other nations, but that the perception of American power was at least as important as the actuality, it was therefore intolerable to him for the Soviet Union to be more advanced in the field of space exploration. He was determined that the United States should compete, sought a challenge that maximized its chances of winning; the Soviet Union had better booster rockets, which meant that Kennedy needed to choose a goal, beyond the capacity of the existing generation of rocketry, one where the US and Soviet Union would be starting from a position of equality – something spectacular if it could not be justified on military, economic, or scientific grounds.
After consulting with his experts and advisors, he chose such a project: to land a man on the Moon and return him to the Earth. This project had a name: Project Apollo. An early and crucial decision was the adoption of lunar orbit rendezvous, under which a specialized spacecraft would land on the lunar surface; the Apollo spacecraft therefore had three primary components: a command module with a cabin for the three astronauts, the only part that would return to Earth. This configuration could be launched by the Saturn V rocket, under development; the initial crew assignment of Frank Borman as Commander, Michael Collins as Command Module Pilot and William Anders as Lunar Module Pilot for the third crewed Apollo flight was announced on November 20, 1967. Collins was replaced by Jim Lovell in July 1968, after suffering a cervical disc herniation that required surgery to repair; this crew was unique among pre-Space Shuttle era missions in that the commander was not the most experienced member of the crew: Lovell had flown twice before, on Gemini VII and Gemini XII.
This would be the first case of a commander of a previous mission flying as a non-commander. The backup crew assignment of Neil Armstrong as Commander, Lovell as CMP, Buzz Aldrin as LMP for the third crewed Apollo flight was announced at the same time as the prime crew; when Lovell was reassigned to the prime crew, Aldrin was moved to CMP, Fred Haise was brought in as backup LMP. Armstrong would command Apollo 11, with Aldrin as LMP and Collins as CMP. Haise served on the backup crew of Apollo 11 as LMP and flew on Apollo 13 as LMP. During Projects Mercury and Gemini, each mission had a backup crew. For Apollo, a third crew of astronauts was known as the support crew; the support crew maintained the flight plan and mission ground rules, ensured that the prime and backup crews were apprised of any changes. The support crew developed procedures in the simulators those for emergency situations, so that the prime and backup crews could practice and master them in their simulator training. For Apollo 8, the support
Gutenberg is a lunar impact crater that lies along the west edge of Mare Fecunditatis, in the eastern part of the visible Moon. It is named after German inventor Johannes Gutenberg. To the southeast are the craters Goclenius and Colombo. To the west-southwest is the crater Gaudibert, across the Montes Pyrenaeus that run south from Gutenberg; the rim of Gutenberg is worn and eroded, most notably in the east where it is broken by the overlapping crater Gutenberg E. This crater in turn has gaps in its southeast and southwest rims, forming a passage to the lunar mare to the east. There are clefts and valleys in the southern rim where it joins Gutenberg C; the crater Gutenberg A intrudes into the southwest rim. The floors of Gutenberg and Gutenberg E have been flooded in the past by lava, forming a flat plain across the bottom; this surface is broken across the northeast by a pair of clefts that form a part of the Rimae Goclenius. These extend northwest from the Goclenius region; the central rise of Gutenberg is a semi-circular range of hills that are the most prominent in the south, the concave part lies open to the east.
The floor is otherwise not marred by any significant craters. By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint, closest to Gutenberg. Lunar Photo of the Day, "Land of Manna", October 5, 2006, showing Gutenberg and vicinity
Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption at temperatures from 700 to 1,200 °C. The structures resulting from subsequent solidification and cooling are sometimes described as lava; the molten rock is formed in the interior of some planets, including Earth, some of their satellites, though such material located below the crust is referred to by other terms. A lava flow is a moving outpouring of lava created during a non-explosive effusive eruption; when it has stopped moving, lava solidifies to form igneous rock. The term lava flow is shortened to lava. Although lava can be up to 100,000 times more viscous than water, lava can flow great distances before cooling and solidifying because of its thixotropic and shear thinning properties. Explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows; the word lava comes from Italian, is derived from the Latin word labes which means a fall or slide.
The first use in connection with extruded magma was in a short account written by Francesco Serao on the eruption of Vesuvius in 1737. Serao described "a flow of fiery lava" as an analogy to the flow of water and mud down the flanks of the volcano following heavy rain; the composition of all lava of the Earth's crust is dominated by silicate minerals feldspars, pyroxenes, amphiboles and quartz. Igneous rocks, which form lava flows when erupted, can be classified into three chemical types: felsic and mafic; these classes are chemical, the chemistry of lava tends to correlate with the magma temperature, its viscosity and its mode of eruption. Felsic or silicic lavas such as rhyolite and dacite form lava spines, lava domes or "coulees" and are associated with pyroclastic deposits. Most silicic lava flows are viscous, fragment as they extrude, producing blocky autobreccias; the high viscosity and strength are the result of their chemistry, high in silica, potassium and calcium, forming a polymerized liquid rich in feldspar and quartz, thus has a higher viscosity than other magma types.
Felsic magmas can erupt at temperatures as low as 650 to 750 °C. Unusually hot rhyolite lavas, may flow for distances of many tens of kilometres, such as in the Snake River Plain of the northwestern United States. Intermediate or andesitic lavas are lower in aluminium and silica, somewhat richer in magnesium and iron. Intermediate lavas form andesite domes and block lavas, may occur on steep composite volcanoes, such as in the Andes. Poorer in aluminium and silica than felsic lavas, commonly hotter, they tend to be less viscous. Greater temperatures tend to destroy polymerized bonds within the magma, promoting more fluid behaviour and a greater tendency to form phenocrysts. Higher iron and magnesium tends to manifest as a darker groundmass, occasionally amphibole or pyroxene phenocrysts. Mafic or basaltic lavas are typified by their high ferromagnesian content, erupt at temperatures in excess of 950 °C. Basaltic magma is high in iron and magnesium, has lower aluminium and silica, which taken together reduces the degree of polymerization within the melt.
Owing to the higher temperatures, viscosities can be low, although still thousands of times higher than water. The low degree of polymerization and high temperature favors chemical diffusion, so it is common to see large, well-formed phenocrysts within mafic lavas. Basalt lavas tend to produce low-profile shield volcanoes or "flood basalt fields", because the fluidal lava flows for long distances from the vent; the thickness of a basalt lava on a low slope, may be much greater than the thickness of the moving lava flow at any one time, because basalt lavas may "inflate" by supply of lava beneath a solidified crust. Most basalt lavas are of pāhoehoe types, rather than block lavas. Underwater, they can form pillow lavas, which are rather similar to entrail-type pahoehoe lavas on land. Ultramafic lavas such as komatiite and magnesian magmas that form boninite take the composition and temperatures of eruptions to the extreme. Komatiites contain over 18% magnesium oxide, are thought to have erupted at temperatures of 1,600 °C.
At this temperature there is no polymerization of the mineral compounds, creating a mobile liquid. Most if not all ultramafic lavas are no younger than the Proterozoic, with a few ultramafic magmas known from the Phanerozoic. No modern komatiite lavas are known, as the Earth's mantle has cooled too much to produce magnesian magmas; some lavas of unusual composition have erupted onto the surface of the Earth. These include: Carbonatite and natrocarbonatite lavas are known from Ol Doinyo Lengai volcano in Tanzania, the sole example of an active carbonatite volcano. Iron oxide lavas are thought to be the source of the iron ore at Kiruna, Sweden which formed during the Proterozoic. Iron oxide lavas of Pliocene age occur at the El Laco volcanic complex on the Chile-Argentina border. Iron oxide lavas are thought to be the result of immiscible separation of iron oxide magma from a parental magma of calc-alkaline or alkaline composition. Sulfur lava flows up to 250 metres 10 metres wide occur at Lastarria volcano, Chile.
They were formed by the melting of sulfur deposits at temperatures as low as 113 °C
Apollo 16 was the tenth manned mission in the United States Apollo space program, the fifth and penultimate to land on the Moon, the second to land in the lunar highlands. The second of the so-called "J missions," it was crewed by Commander John Young, Lunar Module Pilot Charles Duke and Command Module Pilot Ken Mattingly. Launched from the Kennedy Space Center in Florida at 12:54 PM EST on April 16, 1972, the mission lasted 11 days, 1 hour, 51 minutes, concluded at 2:45 PM EST on April 27. Young and Duke spent 71 hours—just under three days—on the lunar surface, during which they conducted three extra-vehicular activities or moonwalks, totaling 20 hours and 14 minutes; the pair drove the Lunar Roving Vehicle, the second produced and used on the Moon, for 26.7 kilometers. On the surface and Duke collected 95.8 kilograms of lunar samples for return to Earth, while Command Module Pilot Ken Mattingly orbited in the command and service module above to perform observations. Mattingly spent 64 revolutions in lunar orbit.
After Young and Duke rejoined Mattingly in lunar orbit, the crew released a subsatellite from the service module. During the return trip to Earth, Mattingly performed a one-hour spacewalk to retrieve several film cassettes from the exterior of the service module. Apollo 16's landing spot in the highlands was chosen to allow the astronauts to gather geologically older lunar material than the samples obtained in three of the first four Moon landings, which were in or near lunar maria. Samples from the Descartes Formation and the Cayley Formation disproved a hypothesis that the formations were volcanic in origin. Mattingly had been assigned to the prime crew of Apollo 13, but was exposed to rubella through Duke, at that time on the back-up crew for Apollo 13, who had caught it from one of his children, he never contracted the illness, but was removed from the crew and replaced by his backup, Jack Swigert, three days before the launch. Young, a captain in the United States Navy, had flown on three spaceflights prior to Apollo 16: Gemini 3, Gemini 10 and Apollo 10, which orbited the Moon.
One of 19 astronauts selected by NASA in April 1966, Duke had never flown in space before Apollo 16. He served on the support crew of Apollo 10 and was a capsule communicator for Apollo 11. Although not announced, the original backup crew consisted of Fred W. Haise, William R. Pogue and Gerald P. Carr, who were targeted for the prime crew assignment on Apollo 19. However, after the cancellations of Apollos 18 and 19 were finalized in September 1970 this crew would not rotate to a lunar mission as planned. Subsequently and Mitchell were recycled to serve as members of the backup crew after returning from Apollo 14, while Pogue and Carr were reassigned to the Skylab program where they flew on Skylab 4. Anthony W. England Karl G. Henize Henry W. Hartsfield Jr. Robert F. Overmyer Donald H. Peterson The insignia of Apollo 16 is dominated by a rendering of an American eagle and a red and blue shield, representing the people of the United States, over a gray background representing the lunar surface.
Overlaying the shield is a gold NASA vector, orbiting the Moon. On its gold-outlined blue border, there are 16 stars, representing the mission number, the names of the crew members: Young, Duke; the insignia was designed from ideas submitted by the crew of the mission. Apollo 16 was the second of the Apollo type J missions, featuring the use of the Lunar Roving Vehicle, increased scientific capability, lunar surface stays of three days; as Apollo 16 was the penultimate mission in the Apollo program and there was no new hardware or procedures to test on the lunar surface, the last two missions presented opportunities for astronauts to clear up some uncertainties in understanding the Moon's properties. Although previous Apollo expeditions, including Apollo 14 and Apollo 15, obtained samples of pre-mare lunar material, before lava began to upwell from the Moon's interior and flood the low areas and basins, none had visited the lunar highlands. Apollo 14 had visited and sampled a ridge of material, ejected by the impact that created the Mare Imbrium impact basin.
Apollo 15 had sampled material in the region of Imbrium, visiting the basin's edge. There remained the possibility, because the Apollo 14 and Apollo 15 landing sites were associated with the Imbrium basin, that different geologic processes were prevalent in areas of the lunar highlands far from Mare Imbrium. Several members of the scientific community remarked that the central lunar highlands resembled regions on Earth that were created by volcanic processes and hypothesized the same might be true on the Moon, they had hoped. Two locations on the Moon were given primary consideration for exploration by the Apollo 16 expedition: the Descartes Highlands region west of Mare Nectaris and the crater Alphonsus. At Descartes, the Cayley and Descartes formations were the primary areas of interest in that scientists suspected, based on telescopic and orbital imagery, that the terrain found there was formed by magma more viscous than that which formed the lunar maria; the Cayley Formation's age was approximated to be about the same as Mare Imbrium based on the local frequency of impact craters.
The considerable distance between the Descartes site and previous Apollo landing sites would be beneficial for the network of geophysical instruments, portions of which were deployed on each Apollo expedition beginning with Apollo 12. At the Alphonsus, three scientific objectives were determined to be of primary int
Goclenius is a lunar impact crater, located near the west edge of Mare Fecunditatis. It lies to the southeast of the lava-flooded crater Gutenberg, north of Magelhaens. To the northwest is a parallel rille system that follow a course toward the northwest, running for a length of up to 240 kilometers; this feature is named the Rimae Goclenius. The rim of this crater is worn and irregular, having a somewhat egg-like outline; the crater floor has been covered in lava, a rille cuts across the floor towards the northwest, in the same direction as the other members of the Rimae Goclenius. A similar rille lies across the floor of Gutenberg, it is that these features were all formed at the same time, after the original craters were created. There is a low central rise located to the northwest of the crater's midpoint. By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint, closest to Goclenius; the following craters have been renamed by the IAU.
Goclenius A — See Ibn Battuta
An impact crater is an circular depression in the surface of a planet, moon, or other solid body in the Solar System or elsewhere, formed by the hypervelocity impact of a smaller body. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters have raised rims and floors that are lower in elevation than the surrounding terrain. Impact craters range from small, bowl-shaped depressions to large, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth. Impact craters are the dominant geographic features on many solid Solar System objects including the Moon, Callisto and most small moons and asteroids. On other planets and moons that experience more active surface geological processes, such as Earth, Mars, Europa, Io and Titan, visible impact craters are less common because they become eroded, buried or transformed by tectonics over time. Where such processes have destroyed most of the original crater topography, the terms impact structure or astrobleme are more used.
In early literature, before the significance of impact cratering was recognised, the terms cryptoexplosion or cryptovolcanic structure were used to describe what are now recognised as impact-related features on Earth. The cratering records of old surfaces, such as Mercury, the Moon, the southern highlands of Mars, record a period of intense early bombardment in the inner Solar System around 3.9 billion years ago. The rate of crater production on Earth has since been lower, but it is appreciable nonetheless; this indicates that there should be far more young craters on the planet than have been discovered so far. The cratering rate in the inner solar system fluctuates as a consequence of collisions in the asteroid belt that create a family of fragments that are sent cascading into the inner solar system. Formed in a collision 160 million years ago, the Baptistina family of asteroids is thought to have caused a large spike in the impact rate causing the Chicxulub impact that may have triggered the extinction of the non-avian dinosaurs 66 million years ago.
Note that the rate of impact cratering in the outer Solar System could be different from the inner Solar System. Although Earth's active surface processes destroy the impact record, about 190 terrestrial impact craters have been identified; these range in diameter from a few tens of meters up to about 300 km, they range in age from recent times to more than two billion years, though most are less than 500 million years old because geological processes tend to obliterate older craters. They are selectively found in the stable interior regions of continents. Few undersea craters have been discovered because of the difficulty of surveying the sea floor, the rapid rate of change of the ocean bottom, the subduction of the ocean floor into Earth's interior by processes of plate tectonics. Impact craters are not to be confused with landforms that may appear similar, including calderas, glacial cirques, ring dikes, salt domes, others. Daniel M. Barringer, a mining engineer, was convinced that the crater he owned, Meteor Crater, was of cosmic origin.
Yet, most geologists at the time assumed. In the 1920s, the American geologist Walter H. Bucher studied a number of sites now recognized as impact craters in the United States, he concluded they had been created by some great explosive event, but believed that this force was volcanic in origin. However, in 1936, the geologists John D. Boon and Claude C. Albritton Jr. revisited Bucher's studies and concluded that the craters that he studied were formed by impacts. Grove Karl Gilbert suggested in 1893. Ralph Baldwin in 1949 wrote that the Moon's craters were of impact origin. Around 1960, Gene Shoemaker revived the idea. According to David H. Levy, Gene "saw the craters on the Moon as logical impact sites that were formed not in eons, but explosively, in seconds." For his Ph. D. degree at Princeton, under the guidance of Harry Hammond Hess, Shoemaker studied the impact dynamics of Barringer Meteor Crater. Shoemaker noted Meteor Crater had the same form and structure as two explosion craters created from atomic bomb tests at the Nevada Test Site, notably Jangle U in 1951 and Teapot Ess in 1955.
In 1960, Edward C. T. Chao and Shoemaker identified at Meteor Crater, proving the crater was formed from an impact generating high temperatures and pressures, they followed this discovery with the identification of coesite within suevite at Nördlinger Ries, proving its impact origin. Armed with the knowledge of shock-metamorphic features, Carlyle S. Beals and colleagues at the Dominion Astrophysical Observatory in Victoria, British Columbia and Wolf von Engelhardt of the University of Tübingen in Germany began a methodical search for impact craters. By 1970, they had tentatively identified more than 50. Although their work was controversial, the American Apollo Moon landings, which were in progress at the time, provided supportive evidence by recognizing the rate of impact cratering on the Moon; because the processes of erosion on the Moon are minimal, craters persist. Since the Earth could be expected to have the same cratering rate as the Moon, it became clear that the Earth had suffered far more impacts than could be seen by counting evident craters.
Impact cratering invo
The lunar maria are large, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed Latin for "seas", by early astronomers who mistook them for actual seas, they are less reflective than the "highlands" as a result of their iron-rich composition, hence appear dark to the naked eye. The maria cover about 16% of the lunar surface on the side visible from Earth; the few maria on the far side are much smaller, residing in large craters. The traditional nomenclature for the Moon includes one oceanus, as well as features with the names lacus and sinus; the last three have the same nature and characteristics. The names of maria refer to sea attributes, or states of mind. Mare Humboldtianum and Mare Smythii were established before the final nomenclature, that of states of mind, was accepted, do not follow this pattern; when Mare Moscoviense was discovered by the Luna 3, the name was proposed by the Soviet Union, it was only accepted by the International Astronomical Union with the justification that Moscow is the state of mind.
The ages of the mare basalts have been determined both by direct radiometric dating and by the technique of crater counting. The radiometric ages range from about 3.16 to 4.2 Ga, whereas the youngest ages determined from crater counting are about 1.2 Ga. Nevertheless, the majority of mare basalts appear to have erupted between about 3 and 3.5 Ga. The few basaltic eruptions that occurred on the far side are old, whereas the youngest flows are found within Oceanus Procellarum on the nearside. While many of the basalts either erupted within, or flowed into, low-lying impact basins, the largest expanse of volcanic units, Oceanus Procellarum, does not correspond to any known impact basin. There are many common misconceptions concerning the spatial distribution of mare basalts. Since many mare basalts fill low-lying impact basins, it was once assumed that the impact event itself somehow caused the volcanic eruption. [Note: current data in fact may not preclude this, although the timing and length of mare volcanism in a number of basins cast some doubt on it.
Initial mare volcanism seems to have begun within 100 million years of basin formation. Although these authors felt that 100 million years was sufficiently long that a correlation between impact and volcanism seemed unlikely, there are problems with this argument; the authors point out that the oldest and deepest basalts in each basin are buried and inaccessible, leading to a sampling bias. It is sometimes suggested that the gravity field of the Earth might preferentially allow eruptions to occur on the near side, but not on the far side. However, in a reference frame rotating with the Moon, the centrifugal acceleration the Moon is experiencing is equal and opposite to the gravitational acceleration of the Earth. There is thus no net force directed towards the Earth; the Earth tides do act to deform the shape of the Moon, but this shape is that of an elongated ellipsoid with high points at both the sub- and anti-Earth points. As an analogy, one should remember that there are two high tides per day on Earth, not one.
Since mare basaltic magmas are denser than upper crustal anorthositic materials, basaltic eruptions might be favored at locations of low elevation where the crust is thin. However, the far side South Pole-Aitken basin contains the lowest elevations of the Moon and yet is only sparingly filled by basaltic lavas. In addition, the crustal thickness beneath this basin is predicted to be much smaller than beneath Oceanus Procellarum. While the thickness of the crust might modulate the quantity of basaltic lavas that reach the surface, crustal thickness by itself cannot be the sole factor controlling the distribution of mare basalts, it is suggested that there is some form of link between the synchronous rotation of the Moon about the Earth, the mare basalts. However, gravitational torques that result in tidal despinning only arise from the moments of inertia of the body, the mare basalts hardly contribute to this. Furthermore, tidal despinning is predicted to have occurred whereas the majority of mare basalts erupted about one billion years later.
The reason that the mare basalts are predominantly located on the near-side hemisphere of the Moon is still being debated by the scientific community. Based on data obtained from the Lunar Prospector mission, it appears that a large proportion of the Moon's inventory of heat producing elements is located within the regions of Oceanus Procellarum and the Imbrium basin, a unique geochemical province now referred to as the Procellarum KREEP Terrane. While the enhancement in heat production within the Procellarum KREEP Terrane is most related to the longevity and intensity of volcanism found there, the mechanism by which KREEP became concentrated within this region is not agreed upon. Using terrestrial classification schemes, all mare basalts are classified as tholeiitic, but specific subclassifications have been invented to further describe the population of lunar basalts. Mare basalts are grouped into three series based on their major element chemistry: high-Ti basalts, low-Ti basalts, very-low-Ti