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
Mare Vaporum is a lunar mare located between the southwest rim of Mare Serenitatis and the southeast rim of Mare Imbrium. The lunar material surrounding the mare is from the Lower Imbrian epoch, the mare material is from the Eratosthenian epoch; the mare lies in an old basin or crater, within the Procellarum basin. The mare is 55,000 km2 in area, it may be from the Pre-Imbrian period. To the south of the mare is a light colored thin line; this feature is Rima Hyginus. The mare is bordered by the mountain range Montes Apenninus; the mare was named by Giovanni Battista Riccioli in 1651. Mare Vaporum at The Moon Wiki Dome in Mare Vaporum - Hook and Dome area Wood, Chuck. "Vaporum: Crater and Basin". Lunar Photo of the Day. Wood, Chuck. "A New Look". Lunar Photo of the Day
Lacus Autumni is a region of lunar mare that lies near the western limb of the Moon. Along this side of the lunar surface is a huge impact basin centered on the Mare Orientale. Two concentric mountain rings surround the Orientale mare, the inner ring being named Montes Rook and an outer ring called the Montes Cordillera. Lacus Autumni lies in the northeastern quadrant of the gap between these two mountain rings; this section of the lunar surface is difficult to observe directly from the Earth. The selenographic coordinates of the center of the mare are 9.9° S, 83.9° W. It is 195 kilometres long and trends from the southeast to the northwest, reaching a maximum width of 90–100 kilometres; the irregular appearance results from the lunar basalt emerging from the surface to fill in low areas between hummocky hills. The name of the feature was approved by the IAU in 1970. NASA lunar Atlas Lunar Orbiter Photo Number IV-181-H2
The Gravity Recovery and Interior Laboratory was an American lunar science mission in NASA's Discovery Program which used high-quality gravitational field mapping of the Moon to determine its interior structure. The two small spacecraft GRAIL A and GRAIL B were launched on 10 September 2011 aboard a single launch vehicle: the most-powerful configuration of a Delta II, the 7920H-10. GRAIL A separated from the rocket about nine minutes after launch, GRAIL B followed about eight minutes later, they arrived at their orbits around the Moon 25 hours apart. The first probe entered orbit on 31 December 2011 and the second followed on 1 January 2012; the two spacecraft impacted the Lunar surface on December 17, 2012. Maria Zuber of the Massachusetts Institute of Technology is GRAIL's principal investigator. NASA's Jet Propulsion Laboratory manages the project; as of August 5, 2011, the program has cost US$496 million. Upon launch the spacecraft were named GRAIL A and GRAIL B and a contest was opened to school children to select names.
Nearly 900 classrooms from 45 states, Puerto Rico and the District of Columbia, participated in the contest. The winning names and Flow, were suggested by 4th grade students at Emily Dickinson Elementary School in Bozeman, Montana; each spacecraft transmitted and received telemetry from the other spacecraft and Earth-based facilities. By measuring the change in distance between the two spacecraft, the gravity field and geological structure of the Moon was obtained; the two spacecraft were able to detect small changes in the distance between one another. Changes in distance as small as one micron were measurable; the gravitational field of the Moon was mapped in unprecedented detail. Map the structure of the lunar crust and lithosphere Understand the asymmetric thermal evolution of the Moon Determine the subsurface structure of impact basins and the origin of lunar mascons Ascertain the temporal evolution of crustal brecciation and magmatism Constrain the deep interior structure of the Moon Place limits on the size of the Moon's inner coreThe data collection phase of the mission lasted from 7 Mar 2012 to 29 May 2012, for a total of 88 days.
A second phase, at a lower altitude, of data collection began 31 Aug 2012, was followed by 12 months of data analysis. On 5 Dec 2012 NASA released a gravity map of the Moon made from GRAIL data; the knowledge acquired will aid understanding of the evolutionary history of the terrestrial planets and computations of lunar orbits. Ka band Lunar Gravity Ranging System, derived from the Gravity Recovery and Climate Experiment instrument. 90% of the GRACE software was reused for GRAIL. Radio science beacon Moon Knowledge Acquired by Middle school students; each MoonKAM system consists of four camera heads. Click here for a MoonKAM photo from lunar orbit. Thrusters aboard each spacecraft were capable of producing 22 newtons; each spacecraft was fueled with 103.5 kilograms of hydrazine to be used by the thrusters and main engine to enable the spacecraft to enter lunar orbit and transition to the science phase of its mission. The propulsion subsystem consisted of a main fuel tank and a Re-repressurization system which were activated shortly after lunar orbit insertion.
All times are in EDT. Unlike the Apollo program missions, which took three days to reach the Moon, GRAIL made use of a three- to four-month low-energy trans-lunar cruise well outside the Moon's orbit and passing near the Sun-Earth Lagrange point L1 before looping back to rendezvous with the Moon; this extended and circuitous trajectory enabled the mission to reduce fuel requirements, protect instruments and reduce the velocity of the two spacecraft at lunar arrival to help achieve the low 50 km orbits with separation between the spacecraft of 175 to 225 km. The tight tolerances in the flight plan left little room for error correction leading to a launch window lasting one second and providing only two launch opportunities per day; the primary science phase of GRAIL lasted for 88 days, from 7 Mar 2012 to 29 May 2012. It was followed by a second science phase starting on 8 Aug; the gravity mapping technique was similar to that used by Gravity Recovery and Climate Experiment, the spacecraft design was based on XSS-11.
The orbital insertion dates were December 31, 2011 and January 1, 2012. The spacecraft were operated over the 88-day acquisition phase, divided into three 27.3 day long nadir-pointed mapping cycles. Twice each day there was an 8-hour pass in view of the Deep Space Network for transmission of science and "E/PO MoonKam" data. At the end of the science phase and a mission extension, the spacecrafts were powered down and decommissioned over a five-day period; the spacecraft impacted the lunar surface on December 17, 2012. Both spacecraft impacted an unnamed lunar mountain between Philolaus and Mouchez at 75.62°N 26.63°W / 75.62. Ebb, the lead spacecraft in formation, impacted first. Flow impacted moments later; each spacecraft was traveling at 3,760 miles per hour. A final experiment was conducted during the final days of the mission. Main engines aboard the spacecraft were fired. Data from that effort will be used by mission planners to validate fuel consumption computer models to improve predictions of fuel needs for future missions.
NASA has announced that the crash site will be named after GRAIL collaborator and first American woman in space, Sally Ride. GRAIL: Mission NASA NASA GRAIL – mission home page MIT GRAIL Home Page NASA Science Missions: GRAIL (Gravity Recovery and Interior
Yukio Mishima is the pen name of Kimitake Hiraoka, a Japanese author, playwright, model, film director and founder of the Tatenokai. Mishima is considered one of the most important Japanese authors of the 20th century, he was considered for the Nobel Prize in Literature in 1968, but the award went to his countryman Yasunari Kawabata. His works include the novels Confessions of a Mask and The Temple of the Golden Pavilion, the autobiographical essay Sun and Steel. Mishima’s work is characterized by its luxurious vocabulary and decadent metaphors, its fusion of traditional Japanese and modern Western literary styles, its obsessive assertions of the unity of beauty and death. A fierce critic of Marxist ideologies, Mishima formed an unarmed civilian militia for the avowed purpose of defending the Japanese emperor in the event of a revolution by Japanese communists. On November 25, 1970, Mishima and four members of his militia entered a military base in central Tokyo, took the commandant hostage, tried to persuade the soldiers at the base to join them in supporting the emperor and overturning Japan's pacifist Constitution.
When this was unsuccessful, Mishima committed suicide by seppuku. Mishima was born in the Yotsuya district of Tokyo, his father was Azusa Hiraoka, a government official, his mother, was the daughter of the 5th principal of the Kaisei Academy. Shizue's father, Kenzō Hashi, was a scholar of Chinese classics, the Hashi family had served the Maeda clan for generations in Kaga Domain. Mishima's paternal grandparents were Natsuko Hiraoka, he had a younger sister, who died of typhus in 1945 at the age of 17, a younger brother, Chiyuki. Mishima's early childhood was dominated by the presence of his grandmother, who took the boy, separating him from his immediate family for several years. Natsuko was the granddaughter of Matsudaira Yoritaka, the daimyō of Shishido in Hitachi Province, had been raised in the household of Prince Arisugawa Taruhito. Through his grandmother, Mishima was a direct descendant of Tokugawa Ieyasu. Natsuko was prone to violence and morbid outbursts, which are alluded to in Mishima's works.
It is to Natsu. Natsuko did not allow Mishima to venture into the sunlight, to engage in any kind of sport or to play with other boys. Mishima returned to his immediate family when he was 12, his father, a man with a taste for military discipline, employed parenting tactics such as holding the young boy up to the side of a speeding train. He raided Mishima's room for evidence of an "effeminate" interest in literature and ripped apart the boy's manuscripts. At the age of six, Mishima enrolled in the Peers' School in Tokyo. At twelve, Mishima began to write his first stories, he voraciously read the works of numerous classic Japanese authors as well as Raymond Radiguet, Oscar Wilde, Rainer Maria Rilke and other European authors, both in translation and in the original. He studied German and English. After six years at school, he became the youngest member of the editorial board of its literary society. Mishima was attracted to the works of the Japanese author Michizō Tachihara, which in turn created an appreciation for classical Japanese poetry form of waka.
Mishima's first published works included waka poetry. He was invited to write a short story for the Gakushūin literary magazine and submitted Hanazakari no Mori, a story in which the narrator describes the feeling that his ancestors somehow still live within him. Mishima's teachers were so impressed that they recommended the story to the prestigious literary magazine Bungei-Bunka; the story makes use of the metaphors and aphorisms that became his trademarks and was published in book form in 1944 in a limited edition because of the wartime shortage of paper. In order to protect him from a possible backlash from his schoolmates, his teachers coined the pen-name "Yukio Mishima". Mishima's story Tabako, published in 1946, describes some of the scorn and bullying he faced at school when he confessed to members of the school's rugby union club that he belonged to the literary society; this trauma provided material for the story Shi o Kaku Shōnen in 1954. Mishima received a draft notice for the Imperial Japanese Army during World War II.
At the time of his medical check up, he had a cold, the young army doctor heard rales from the lung, misdiagnosed as tuberculosis. Although his authoritarian father had forbidden him to write any further stories, Mishima continued to write every night in secret and protected by his mother, always the first to read a new story. Attending lectures during the day and writing at night, Mishima graduated from the University of Tokyo in 1947, he obtained a position as an official in the government's Finance Ministry and was set up for a promising career. However, Mishima had exhausted himself so much that his father agreed to his resigning from the position during the first year of employment in order to devote himself to writing. Mishima wrote novels
Mass concentration (astronomy)
In astronomy and astrophysics, a mass concentration is a region of a planet or moon's crust that contains a large positive gravitational anomaly. In general, the word "mascon" can be used as a noun to refer to an excess distribution of mass on or beneath the surface of an astronomical body, such as is found around Hawaii on Earth. However, this term is most used to describe a geologic structure that has a positive gravitational anomaly associated with a feature that might otherwise have been expected to have a negative anomaly, such as the "mascon basins" on the Moon. Typical examples of mascon basins on the Moon are the Imbrium, Serenitatis and Orientale impact basins, all of which exhibit significant topographic depressions and positive gravitational anomalies. Examples of mascon basins on Mars include the Argyre and Utopia basins. Theoretical considerations imply that a topographic low in isostatic equilibrium would exhibit a slight negative gravitational anomaly. Thus, the positive gravitational anomalies associated with these impact basins indicate that some form of positive density anomaly must exist within the crust or upper mantle, supported by the lithosphere.
One possibility is that these anomalies are due to dense mare basaltic lavas, which might reach up to 6 kilometers in thickness for the Moon. While these lavas contribute to the observed gravitational anomalies, uplift of the crust-mantle interface is required to account for their magnitude. Indeed, some mascon basins on the Moon do not appear to be associated with any signs of volcanic activity. Theoretical considerations in either case indicate; the huge expanse of mare basaltic volcanism associated with Oceanus Procellarum does not possess a positive gravitational anomaly. Because of its mascons, the Moon has only four "frozen orbit" inclination zones where a lunar satellite can stay in a low orbit indefinitely. Lunar subsatellites were released on two of the last three Apollo manned lunar landing missions in 1971 and 1972, it was only in 2001 that the mascons were mapped and the frozen orbits were discovered. Since their identification in 1968, the origin of the mascons beneath the surface of the Moon has been subject to much debate, but is now regarded as being the result of the impact of asteroids during the Late Heavy Bombardment.
Lunar mascons alter the local gravity above and around them sufficiently that low and uncorrected satellite orbits around the Moon are unstable on a timescale of months or years. The small perturbations in the orbits accumulate and distort the orbit enough that the satellite impacts the surface; the Luna-10 orbiter was the first artificial object to orbit the Moon and it returned tracking data indicating that the lunar gravitational field caused larger than expected perturbations due to'roughness' of the lunar gravitational field. The Lunar mascons were discovered by Paul M. Muller and William L. Sjogren of the NASA Jet Propulsion Laboratory in 1968 from a new analytic method applied to the precise navigation data from the unmanned pre-Apollo Lunar Orbiter spacecraft; this discovery observed the consistent 1:1 correlation between large positive gravity anomalies and depressed circular basins on the Moon. This fact places key limits on models attempting to follow the history of the Moon's geological development and explain the current lunar internal structures.
At that time, one of NASA's highest priority "tiger team" projects was to explain why the Lunar Orbiter spacecraft being used to test the accuracy of Project Apollo navigation were experiencing errors in predicted position of ten times the mission specification. This meant that the predicted landing areas were 100 times as large as those being defined for reasons of safety. Lunar orbital effects principally resulting from the strong gravitational perturbations of the mascons were revealed as the cause. William Wollenhaupt and Emil Schiesser of the NASA Manned Spacecraft Center in Houston worked out the "fix", first applied to Apollo 12 and permitted its landing within 163 m of the target, the previously-landed Surveyor 3 spacecraft. In May 2013 a NASA study was published with results from the twin GRAIL probes, that mapped mass concentrations on Earth's Moon. Lunar orbit § Perturbation effects