20°00′N 31°00′E / 20.0°N 31.0°E / 20.0; 31.0
95-617: Taurus–Littrow is a lunar valley located on the near side at the coordinates 20°00′N 31°00′E / 20.0°N 31.0°E / 20.0; 31.0 . It served as the landing site for the American Apollo 17 mission in December 1972, the last crewed mission to the Moon. The valley is located on the southeastern edge of Mare Serenitatis along a ring of mountains formed between 3.8 and 3.9 billion years ago when
190-526: A lunar eclipse , always illuminated by the Sun, but from Earth the visible illumination shifts during its orbit, producing the lunar phases . The Moon is the brightest celestial object in Earth's night sky . This is mainly due to its large angular diameter , while the reflectance of the lunar surface is comparable to that of asphalt . The apparent size is nearly the same as that of the Sun, allowing it to cover
285-440: A 4.25 billion-year-old coarse-grained troctolite composed primarily of olivine and plagioclase , in the valley as part of a rake sample. The sample has been called the most interesting to be returned from the Moon and has been the subject of thermochronological calculation in an effort to determine whether the Moon generated a core dynamo or formed a metallic core , an inquiry that has yielded results in apparent support of
380-528: A combination of operational and scientific justifications. A landing at Tycho was thought to exceed mission safety constraints because of the rough terrain found there. A landing on the far side in Tsiolkovskiy would add the expense and logistical difficulty of communications satellites that would be necessary to maintain contact between the crew and mission control during surface operations, and data from Apollo 12 had already afforded an opportunity to gauge
475-425: A decisive role on local surface temperatures . Parts of many craters, particularly the bottoms of many polar craters, are permanently shadowed, these " craters of eternal darkness " have extremely low temperatures. The Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at 35 K (−238 °C; −397 °F) and just 26 K (−247 °C; −413 °F) close to
570-434: A few kilometers wide), shallower, and more irregularly shaped than impact craters. They also lack the upturned rims characteristic of impact craters. Several geologic provinces containing shield volcanoes and volcanic domes are found within the near side maria. There are also some regions of pyroclastic deposits , scoria cones and non-basaltic domes made of particularly high viscosity lava. Almost all maria are on
665-503: A global dipolar magnetic field and only has crustal magnetization likely acquired early in its history when a dynamo was still operating. Early in its history, 4 billion years ago, its magnetic field strength was likely close to that of Earth today. This early dynamo field apparently expired by about one billion years ago, after the lunar core had crystallized. Theoretically, some of the remnant magnetization may originate from transient magnetic fields generated during large impacts through
760-718: A hospitable environment for future astronauts, protecting them from extreme temperatures, solar radiation, and micrometeorites. However, challenges include accessibility and risks of avalanches and cave-ins. This discovery offers potential for future lunar bases or emergency shelters. The main features visible from Earth by the naked eye are dark and relatively featureless lunar plains called maria (singular mare ; Latin for "seas", as they were once believed to be filled with water) are vast solidified pools of ancient basaltic lava. Although similar to terrestrial basalts, lunar basalts have more iron and no minerals altered by water. The majority of these lava deposits erupted or flowed into
855-533: A landscape featuring craters of all ages. The Moon was volcanically active until 1.2 billion years ago, which laid down the prominent lunar maria . Most of the mare basalts erupted during the Imbrian period , 3.3–3.7 billion years ago, though some are as young as 1.2 billion years and some as old as 4.2 billion years. There are differing explanations for the eruption of mare basalts, particularly their uneven occurrence which mainly appear on
950-472: A large cluster, a constituent of a nearby ray of Tycho. Evidence from the Apollo 17 mission indicates that the massifs surrounding the valley are composed primarily of feldspar-rich breccia and that basalt underlies the valley floor, a result of the lava flows during the valley's geologic history. Seismic studies suggest that the basalt below the valley floor is greater than 1400 meters (4600 feet) thick. Above
1045-600: A large object impacted the Moon, forming the Serenitatis basin and pushing rock outward and upward. Taurus–Littrow is located in the Taurus mountain range and south of Littrow crater , features from which the valley received its name. The valley's name, coined by the Apollo 17 crew, was approved by the International Astronomical Union in 1973. Data collected during Apollo 17 indicate that
SECTION 10
#17327986562131140-459: A number of different scientific objectives in order to maximize the expedition's scientific productivity. Landing sites considered and rejected for previous missions received reconsideration. Taurus–Littrow was one of several potential landing sites considered for Apollo 17 along with Tycho crater, Copernicus crater, and Tsiolkovskiy crater on the far side , among others. Planners ultimately eliminated all but Taurus–Littrow from consideration for
1235-428: A radius of about 500 kilometres (310 mi). This structure is thought to have developed through the fractional crystallization of a global magma ocean shortly after the Moon's formation 4.5 billion years ago. Crystallization of this magma ocean would have created a mafic mantle from the precipitation and sinking of the minerals olivine , clinopyroxene , and orthopyroxene ; after about three-quarters of
1330-481: A result of tectonic events. Ejecta blanket An ejecta blanket is a generally symmetrical apron of ejecta that surrounds an impact crater ; it is layered thickly at the crater's rim and thin to discontinuous at the blanket's outer edge. The impact cratering is one of the basic surface formation mechanisms of the solar system bodies (including the Earth) and the formation and emplacement of ejecta blankets are
1425-458: A satellite with similar mass and iron content to the Moon into orbit far outside Earth's Roche limit . Even satellites that initially pass within the Roche limit can reliably and predictably survive, by being partially stripped and then torqued onto wider, stable orbits. On November 1, 2023, scientists reported that, according to computer simulations, remnants of Theia could still be present inside
1520-497: A series of projections extending about six kilometres (3.7 mi) from the south massif across the floor. Pre-Apollo 17 analyses suggested that this deposit might have been the result of an avalanche originating from the northern slope of the south massif. Analysis of the mantle material collected during Apollo 17 revealed a finely-grained texture interspersed with larger fragments of rock. Evidence from these samples, together with visual observation during Apollo 17, indicate that
1615-475: A study of Ina , a tiny depression in Lacus Felicitatis , found jagged, relatively dust-free features that, because of the lack of erosion by infalling debris, appeared to be only 2 million years old. Moonquakes and releases of gas indicate continued lunar activity. Evidence of recent lunar volcanism has been identified at 70 irregular mare patches , some less than 50 million years old. This raises
1710-502: A texture resembling snow and a scent resembling spent gunpowder . The regolith of older surfaces is generally thicker than for younger surfaces: it varies in thickness from 10–15 m (33–49 ft) in the highlands and 4–5 m (13–16 ft) in the maria. Beneath the finely comminuted regolith layer is the megaregolith , a layer of highly fractured bedrock many kilometers thick. These extreme conditions are considered to make it unlikely for spacecraft to harbor bacterial spores at
1805-439: A trans-Atlantic flight, 200 times more than on Earth's surface. For further comparison radiation on a flight to Mars is about 1.84 millisieverts per day and on Mars on average 0.64 millisieverts per day, with some locations on Mars possibly having levels as low as 0.342 millisieverts per day. The Moon's axial tilt with respect to the ecliptic is only 1.5427°, much less than the 23.44° of Earth. Because of this small tilt,
1900-414: Is a common feature to be seen on the martian impact craters specifically around fresh impact crater . One-third of the martian impact craters with ≥ 5 km diameter have discernible impact ejecta around. Layered ejecta blanket are plentiful on the surface of Mars as around 90% of ejecta are characterized as layered materials. Though impact cratering and resulted ejecta blanket are ubiquitous features in
1995-489: Is around 3 × 10 atm (0.3 nPa ); it varies with the lunar day. Its sources include outgassing and sputtering , a product of the bombardment of lunar soil by solar wind ions. Elements that have been detected include sodium and potassium , produced by sputtering (also found in the atmospheres of Mercury and Io ); helium-4 and neon from the solar wind; and argon-40 , radon-222 , and polonium-210 , outgassed after their creation by radioactive decay within
SECTION 20
#17327986562132090-532: Is asymmetric, being more dense near the boundary between the Moon's dayside and nightside. Ionizing radiation from cosmic rays , the Sun and the resulting neutron radiation produce radiation levels on average of 1.369 millisieverts per day during lunar daytime , which is about 2.6 times more than on the International Space Station with 0.53 millisieverts per day at about 400 km above Earth in orbit, 5–10 times more than during
2185-561: Is estimated from about 500 km (300 miles) to 1,737 km (1,079 miles). While the giant-impact theory explains many lines of evidence, some questions are still unresolved, most of which involve the Moon's composition. Models that have the Moon acquiring a significant amount of the proto-earth are more difficult to reconcile with geochemical data for the isotopes of zirconium, oxygen, silicon, and other elements. A study published in 2022, using high-resolution simulations (up to 10 particles), found that giant impacts can immediately place
2280-440: Is on average about 1.9 km (1.2 mi) higher than that of the near side. The discovery of fault scarp cliffs suggest that the Moon has shrunk by about 90 metres (300 ft) within the past billion years. Similar shrinkage features exist on Mercury . Mare Frigoris, a basin near the north pole long assumed to be geologically dead, has cracked and shifted. Since the Moon does not have tectonic plates, its tectonic activity
2375-477: Is simply Moon , with a capital M. The noun moon is derived from Old English mōna , which (like all its Germanic cognates) stems from Proto-Germanic *mēnōn , which in turn comes from Proto-Indo-European *mēnsis 'month' (from earlier *mēnōt , genitive *mēneses ) which may be related to the verb 'measure' (of time). Occasionally, the name Luna / ˈ l uː n ə / is used in scientific writing and especially in science fiction to distinguish
2470-574: Is slow and cracks develop as it loses heat. Scientists have confirmed the presence of a cave on the Moon near the Sea of Tranquillity , not far from the 1969 Apollo 11 landing site. The cave, identified as an entry point to a collapsed lava tube, is roughly 45 meters wide and up to 80 m long. This discovery marks the first confirmed entry point to a lunar cave. The analysis was based on photos taken in 2010 by NASA's Lunar Reconnaissance Orbiter . The cave's stable temperature of around 17 °C could provide
2565-476: Is the lowest point on the surface of the Moon. The highest elevations of the Moon's surface are located directly to the northeast, which might have been thickened by the oblique formation impact of the South Pole–Aitken basin. Other large impact basins such as Imbrium , Serenitatis , Crisium , Smythii , and Orientale possess regionally low elevations and elevated rims. The far side of the lunar surface
2660-601: The Grand Canyon in the United States . Along the South Massif lies Bear Mountain, named after a mountain of the same name near Harrison Schmitt's hometown of Silver City , New Mexico . The sculptured hills and East massif make up the eastern edge of the valley and to the west, a scarp cuts across the valley floor and rises about two kilometres (1.2 miles) above it. The North and South massifs funnel into
2755-651: The Solar System , it is the largest and most massive satellite in relation to its parent planet , the fifth largest and most massive moon overall, and larger and more massive than all known dwarf planets . Its surface gravity is about one sixth of Earth's, about half of that of Mars , and the second highest among all Solar System moons, after Jupiter 's moon Io . The body of the Moon is differentiated and terrestrial , with no significant hydrosphere , atmosphere , or magnetic field . It formed 4.51 billion years ago, not long after Earth's formation , out of
2850-477: The same side of the Moon to always face Earth. The Moon's gravitational pull—and, to a lesser extent, the Sun 's—are the main drivers of Earth's tides . In geophysical terms , the Moon is a planetary-mass object or satellite planet . Its mass is 1.2% that of the Earth, and its diameter is 3,474 km (2,159 mi), roughly one-quarter of Earth's (about as wide as the United States from coast to coast ). Within
2945-551: The Apollo 17 LM within the Taurus–Littrow valley in early 2020, later postponed to an indefinite date no earlier the second half of 2021. Moon The Moon is Earth 's only natural satellite . It orbits at an average distance of 384,400 km (238,900 mi), about 30 times the diameter of Earth. Tidal forces between Earth and the Moon have synchronized the Moon's orbital period ( lunar month ) with its rotation period ( lunar day ) at 29.5 Earth days, causing
Taurus–Littrow - Misplaced Pages Continue
3040-452: The Earth and the material accreted and formed the Moon just beyond the Earth's Roche limit of ~ 2.56 R 🜨 . Giant impacts are thought to have been common in the early Solar System. Computer simulations of giant impacts have produced results that are consistent with the mass of the lunar core and the angular momentum of the Earth–Moon system. These simulations show that most of
3135-520: The Earth's moon from others, while in poetry "Luna" has been used to denote personification of the Moon. Cynthia / ˈ s ɪ n θ i ə / is another poetic name, though rare, for the Moon personified as a goddess, while Selene / s ə ˈ l iː n iː / (literally 'Moon') is the Greek goddess of the Moon. The English adjective pertaining to the Moon is lunar , derived from the Latin word for
3230-429: The Earth, due to gravitational anomalies from impact basins. Its shape is more elongated than current tidal forces can account for. This 'fossil bulge' indicates that the Moon solidified when it orbited at half its current distance to the Earth, and that it is now too cold for its shape to restore hydrostatic equilibrium at its current orbital distance. The Moon is by size and mass the fifth largest natural satellite of
3325-469: The Earth-Moon system might be explained by the post-impact mixing of the vaporized material that formed the two, although this is debated. The impact would have released enough energy to liquefy both the ejecta and the Earth's crust, forming a magma ocean. The liquefied ejecta could have then re-accreted into the Earth–Moon system. The newly formed Moon would have had its own magma ocean ; its depth
3420-530: The Earth. The newly formed Moon settled into a much closer Earth orbit than it has today. Each body therefore appeared much larger in the sky of the other, eclipses were more frequent, and tidal effects were stronger. Due to tidal acceleration , the Moon's orbit around Earth has become significantly larger, with a longer period. Following formation, the Moon has cooled and most of its atmosphere has been stripped. The lunar surface has since been shaped by large impact events and many small ones, forming
3515-504: The Moon approximately 10 minutes, taking 5 minutes to rise, and 5 minutes to fall. On average, 120 kilograms of dust are present above the Moon, rising up to 100 kilometers above the surface. Dust counts made by LADEE 's Lunar Dust EXperiment (LDEX) found particle counts peaked during the Geminid , Quadrantid , Northern Taurid , and Omicron Centaurid meteor showers , when the Earth, and Moon pass through comet debris. The lunar dust cloud
3610-458: The Moon derived from the impactor, rather than the proto-Earth. However, models from 2007 and later suggest a larger fraction of the Moon derived from the proto-Earth. Other bodies of the inner Solar System such as Mars and Vesta have, according to meteorites from them, very different oxygen and tungsten isotopic compositions compared to Earth. However, Earth and the Moon have nearly identical isotopic compositions. The isotopic equalization of
3705-495: The Moon for longer than just one lunar orbit. The topography of the Moon has been measured with laser altimetry and stereo image analysis . Its most extensive topographic feature is the giant far-side South Pole–Aitken basin , some 2,240 km (1,390 mi) in diameter, the largest crater on the Moon and the second-largest confirmed impact crater in the Solar System . At 13 km (8.1 mi) deep, its floor
3800-466: The Moon formed around 50 million years after the origin of the Solar System . Historically, several formation mechanisms have been proposed, but none satisfactorily explains the features of the Earth–Moon system. A fission of the Moon from Earth's crust through centrifugal force would require too great an initial rotation rate of Earth. Gravitational capture of a pre-formed Moon depends on an unfeasibly extended atmosphere of Earth to dissipate
3895-455: The Moon is a crescent\decrescent, [REDACTED] \ [REDACTED] , for example in M ☾ 'lunar mass' (also M L ). The lunar geological periods are named after their characteristic features, from most impact craters outside the dark mare , to the mare and later craters, and finally the young, still bright and therefore readily visible craters with ray systems like Copernicus or Tycho . Isotope dating of lunar samples suggests
Taurus–Littrow - Misplaced Pages Continue
3990-558: The Moon's solar illumination varies much less with season than on Earth and it allows for the existence of some peaks of eternal light at the Moon's north pole , at the rim of the crater Peary . The surface is exposed to drastic temperature differences ranging from 120 °C to −171 °C depending on the solar irradiance . Because of the lack of atmosphere, temperatures of different areas vary particularly upon whether they are in sunlight or shadow, making topographical details play
4085-403: The Moon, lūna . Selenian / s ə l iː n i ə n / is an adjective used to describe the Moon as a world, rather than as a celestial object, but its use is rare. It is derived from σελήνη selēnē , the Greek word for the Moon, and its cognate selenic was originally a rare synonym but now nearly always refers to the chemical element selenium . The element name selenium and
4180-502: The Serenitatis basin and Taurus–Littrow formed, the lavas that had seeped through the lunar crust began to flood the low-lying areas. These lava flows were often accompanied by lava fountains that blanketed the surrounding area with tiny glass beads. These glass beads may present as a discoloration of the soil in which they came to rest, including that of the "orange soil" discovered by the Apollo 17 astronauts at Shorty crater . Most of these beads, however, are dark in coloration, to which
4275-494: The Solar System relative to their primary planets. The Moon's diameter is about 3,500 km, more than a quarter of Earth's, with the face of the Moon comparable to the width of either Mainland Australia , Europe or the Contiguous United States (which excludes Alaska , etc.). The whole surface area of the Moon is about 38 million square kilometers, comparable to North and South America combined,
4370-467: The Solar System, categorizable as one of its planetary-mass moons , making it a satellite planet under the geophysical definitions of the term . It is smaller than Mercury and considerably larger than the largest dwarf planet of the Solar System, Pluto . While the minor-planet moon Charon of the Pluto-Charon system is larger relative to Pluto, the Moon is the largest natural satellite of
4465-426: The Sun completely during a total solar eclipse . From Earth about 59% of the lunar surface is visible over time due to cyclical shifts in perspective ( libration ), making parts of the far side of the Moon visible. The Moon has been an important source of inspiration and knowledge for humans, having been crucial to cosmography , mythology, religion , art, time keeping , natural science , and spaceflight . In 1959,
4560-468: The Tycho impact reveals that the majority of them have a downrange ejecta blanket , or debris layer, with a distinctive 'birdsfoot' pattern. Apollo 17 observation data and comparison between the valley's central crater cluster and known Tycho secondary impacts indicate many similarities between them. The valley's central crater cluster has a 'birdsfoot' ejecta pattern that points in the direction of Tycho and
4655-454: The boulders average about four meters in size and are higher in concentration than in other areas of the valley. The Tycho impact, which occurred between 15–20 and 70–95 million years ago, formed secondary crater clusters in various locations of the Moon. Data from the examination of these clusters suggest that the central crater cluster in the valley formed as a result of that impact. Analysis of known secondary impact clusters resulting from
4750-665: The center of the crater. Ejecta which falls within that area is considered proximal ejecta . Beyond 5 radii, the discontinuous debris is considered distal ejecta . Ejecta blankets are found on the terrestrial planets (e.g., Earth, Mars, and Mercury) and satellites (e.g., Moon). Many of the ejecta blankets of Mars are characterized by fluidized flowing across the surface. In contrast, the ejecta blankets and proximal ejecta deposits of Moon and Mercury (or on airless bodies) are attributed to ballistic sedimentation. Lunar fresh impact craters preserve continuous ejecta blanket that are characterized by blocky and high albedo materials. Similar to
4845-413: The combined American landmass having an area (excluding all islands) of 37.7 million square kilometers. The Moon's mass is 1/81 of Earth's, being the second densest among the planetary moons, and having the second highest surface gravity , after Io , at 0.1654 g and an escape velocity of 2.38 km/s ( 8 600 km/h; 5 300 mph) . The Moon is a differentiated body that
SECTION 50
#17327986562134940-415: The crater itself. The possibility that select craters in the valley could be secondary impacts resulting from the Tycho impact presented further opportunity for sampling ejecta from that impact. There are several geologic deposits on the valley floor originating from a variety of events in the geologic timeline of the Moon. One of these formations, the light mantle, is a deposit of lightly colored material in
5035-401: The crater. An ejecta blanket is deposited in the interior regions of the crater rim to the final crater rim and beyond the crater rim. Approximately half the volume of ejecta falls within 1 crater radius of the rim, or 2 radii from the center of the crater. The ejecta blanket becomes thinner with distance and increasingly discontinuous. Over 90% of the debris falls within approximately 5 radii of
5130-433: The crust and mantle. The absence of such neutral species (atoms or molecules) as oxygen , nitrogen , carbon , hydrogen and magnesium , which are present in the regolith , is not understood. Water vapor has been detected by Chandrayaan-1 and found to vary with latitude, with a maximum at ~60–70 degrees; it is possibly generated from the sublimation of water ice in the regolith. These gases either return into
5225-451: The dark appearance of Mare Serenitatis from Earth can be attributed. The valley is elongated along an axis that roughly intersects with center of Mare Serenitatis. Large massifs are located on either side of the valley, named the North and South massifs, respective to their geographic location in relation to each other. The height of these massifs give the valley a depth greater than that of
5320-480: The debris from a giant impact between Earth and a hypothesized Mars-sized body called Theia . The lunar surface is covered in lunar dust and marked by mountains , impact craters , their ejecta , ray-like streaks , rilles and, mostly on the near side of the Moon, by dark maria ("seas"), which are plains of cooled lava . These maria were formed when molten lava flowed into ancient impact basins. The Moon is, except when passing through Earth's shadow during
5415-569: The debris pattern of the light mantle points directly towards the South massif. The latter lends further support to the hypothesis that the light mantle formed as a result of an avalanche from the South massif, perhaps as a result of secondary Tycho impacts. Large-scale analysis suggests that the crater cluster may be part of a larger secondary Tycho cluster, which may include craters on the North massif and other clusters as far north as Littrow crater. If indeed related, these smaller clusters could then form
5510-447: The dense mare basaltic lava flows that fill those basins. The anomalies greatly influence the orbit of spacecraft about the Moon. There are some puzzles: lava flows by themselves cannot explain all of the gravitational signature, and some mascons exist that are not linked to mare volcanism. The Moon has an external magnetic field of less than 0.2 nanoteslas , or less than one hundred thousandth that of Earth . The Moon does not have
5605-514: The depressions associated with impact basins , though the Moon's largest expanse of basalt flooding, Oceanus Procellarum , does not correspond to an obvious impact basin. Different episodes of lava flows in maria can often be recognized by variations in surface albedo and distinct flow margins. As the maria formed, cooling and contraction of the basaltic lava created wrinkle ridges in some areas. These low, sinuous ridges can extend for hundreds of kilometers and often outline buried structures within
5700-468: The energy of the passing Moon. A co-formation of Earth and the Moon together in the primordial accretion disk does not explain the depletion of metals in the Moon. None of these hypotheses can account for the high angular momentum of the Earth–Moon system. The prevailing theory is that the Earth–Moon system formed after a giant impact of a Mars -sized body (named Theia ) with the proto-Earth . The oblique impact blasted material into orbit about
5795-422: The expansion of plasma clouds. These clouds are generated during large impacts in an ambient magnetic field. This is supported by the location of the largest crustal magnetizations situated near the antipodes of the giant impact basins. The Moon has an atmosphere so tenuous as to be nearly vacuum , with a total mass of less than 10 tonnes (9.8 long tons; 11 short tons). The surface pressure of this small mass
SECTION 60
#17327986562135890-1182: The exposed ones. Conversely, mare lava has obscured many impact melt sheets and pools. Impact melts are formed when intense shock pressures from collisions vaporize and melt zones around the impact site. Where still exposed, impact melt can be distinguished from mare lava by its distribution, albedo, and texture. Sinuous rilles , found in and around maria, are likely extinct lava channels or collapsed lava tubes . They typically originate from volcanic vents , meandering and sometimes branching as they progress. The largest examples, such as Schroter's Valley and Rima Hadley , are significantly longer, wider, and deeper than terrestrial lava channels, sometimes featuring bends and sharp turns that again, are uncommon on Earth. Mare volcanism has altered impact craters in various ways, including filling them to varying degrees, and raising and fracturing their floors from uplift of mare material beneath their interiors. Examples of such craters include Taruntius and Gassendi . Some craters, such as Hyginus , are of wholly volcanic origin, forming as calderas or collapse pits . Such craters are relatively rare, and tend to be smaller (typically
5985-542: The extent of ejecta blanket that ranging from size and mass of impactor (meteorite, asteroid, or comet), surface temperature, gravity and atmospheric pressure of target body, the physical characteristics of target rock. The martian ejecta blankets are categorized broadly into three groups based on the observed morphology identified by spacecraft data: a. Layer ejecta pattern: the ejecta blanket seems have formed by fluidization process and composed of single or multiple partial or complete layers of sheet of materials surrounding
6080-510: The first human-made objects to leave Earth and reach another body arrived at the Moon, with the flyby of the Soviet Union 's Luna 1 and the intentional impact of Luna 2 . In 1966, the Moon became the first extraterrestrial body with a soft landing by Luna 9 and a orbital insertion by Luna 10 were achieved . On July 20, 1969, humans for the first time landed on the Moon and any extraterrestrial body, at Mare Tranquillitatis with
6175-427: The flood lavas that erupted onto the surface from partial melting in the mantle confirm the mafic mantle composition, which is more iron-rich than that of Earth. The crust is on average about 50 kilometres (31 mi) thick. The Moon is the second-densest satellite in the Solar System, after Io . However, the inner core of the Moon is small, with a radius of about 350 kilometres (220 mi) or less, around 20% of
6270-436: The formation of the Serenitatis basin, lavas began to upwell from the Moon's interior, filling the basin and forming what is now known as Mare Serenitatis. As a result of these lavas, rock and soil samples from the area that were collected by Apollo 17 astronauts Eugene Cernan and Harrison Schmitt provided insight into the natural history and geologic timeline of the Moon . Somewhere between 100 and 200 million years after
6365-440: The former—an active, churning core which generated a magnetic field, manifested in the magnetism of the sample itself. Further analysis by Garrick-Bethell et al. of the sample reveals nearly unidirectional magnetism—perhaps parallel to that of a larger field—lending further support to the hypothesis that the sample's magnetic properties are the result of a core dynamo in lieu of a singular shock event acting upon it. Rocks sampled in
6460-500: The fresh lunar craters, the Mercurian impact craters also form continuous ejecta deposits of blocky and high albedo materials. Radial structure of ejecta deposits are seen around the lunar impact crater and generally thins out as increase distance form the center of the crater. Presence of boulder materials are also seen in the lunar ejecta deposits. However, the diameter of boulder found in ejecta deposits are directly correlated with
6555-449: The fundamental characteristics associated with impact cratering event. The ejecta materials are considered as the transported materials beyond the transient cavity formed during impact cratering regardless of the state of the target materials. A blanket of ejecta is formed during the formation of meteor impact cratering and is composed usually of the materials of that are ejected from the cratering process. Ejecta materials are deposited on
6650-544: The immediate vicinity of the Lunar Module are mostly vesicular coarse-grained subfloor basalt, with some appearance of fine-grained basalt as well. Much of the valley floor, as indicated by observations of the immediate landing area, is made up of regolith and fragments varying in sizes excavated by several impacts in the Moon's history. As Apollo 17 was the final lunar mission of the Apollo program , planners identified
6745-474: The impact process. These information also give an idea about the planetary environment e.g., gravity and atmospheric effects associated with the impact cratering. Studying impact ejecta is an excellent sampling environment for the future in-situ lunar exploration. Ejecta blanket may not always evenly distributed around an impact crater. Based on the structure, ejecta blanket are described as rampart, lobate, butterfly, splosh, sinuous, etc. Many factors determine
6840-419: The lander Eagle of the United States ' Apollo 11 mission. Five more crews were sent between then and 1972, each with two men landing on the surface. The longest stay was 75 hours by the Apollo 17 crew. Since then, exploration of the Moon has continued robotically, and crewed missions are being planned to return beginning in the late 2020s. The usual English proper name for Earth's natural satellite
6935-402: The layer of subfloor basalt lies a deposit of unconsolidated material of various compositions ranging from volcanic material to impact-formed regolith. The valley floor's unusually low albedo , or reflectivity, is a direct result of the volcanic material and glass beads located there. The deeper craters on the valley floor act as 'natural drill holes' and afforded Apollo 17 the ability to sample
7030-502: The light mantle varies in thickness throughout the valley. Craters located farther away from the south massif penetrate through the light mantle to darker underlying material. Meanwhile, craters close to the south massif as wide as 75 metres (246 ft) do not appear to penetrate to darker material at all. The age of the light mantle is estimated to be about the same as the valley's central crater cluster, or about 70–95 million years old. Apollo 17 discovered and returned Troctolite 76535 ,
7125-421: The magma ocean had crystallized, lower-density plagioclase minerals could form and float into a crust atop. The final liquids to crystallize would have been initially sandwiched between the crust and mantle, with a high abundance of incompatible and heat-producing elements. Consistent with this perspective, geochemical mapping made from orbit suggests a crust of mostly anorthosite . The Moon rock samples of
7220-454: The main outlet of the valley, which in turn opens to Mare Serenitatis, such gap partially blocked by Family mountain. Based on Apollo 17 observations, the valley floor is generally a gently rolling plain. Boulders of various sizes, together with other geologic deposits, are scattered throughout the valley. At the ALSEP lunar experiment deployment area, located west of the immediate landing site,
7315-521: The mantle could be responsible for prolonged activities on the far side in the Orientale basin. The lighter-colored regions of the Moon are called terrae , or more commonly highlands , because they are higher than most maria. They have been radiometrically dated to having formed 4.4 billion years ago, and may represent plagioclase cumulates of the lunar magma ocean. In contrast to Earth, no major lunar mountains are believed to have formed as
7410-406: The mare. Another result of maria formation is the creation of concentric depressions along the edges, known as arcuate rilles . These features occur as the mare basalts sink inward under their own weight, causing the edges to fracture and separate. In addition to the visible maria, the Moon has mare deposits covered by ejecta from impacts. Called cryptomares, these hidden mares are likely older than
7505-524: The near side of the Moon, and cover 31% of the surface of the near side compared with 2% of the far side. This is likely due to a concentration of heat-producing elements under the crust on the near side, which would have caused the underlying mantle to heat up, partially melt, rise to the surface and erupt. Most of the Moon's mare basalts erupted during the Imbrian period , 3.3–3.7 billion years ago, though some being as young as 1.2 billion years and as old as 4.2 billion years. In 2006,
7600-440: The near-side. Causes of the distribution of the lunar highlands on the far side are also not well understood. Topological measurements show the near side crust is thinner than the far side. One possible scenario then is that large impacts on the near side may have made it easier for lava to flow onto the surface. The Moon is a very slightly scalene ellipsoid due to tidal stretching, with its long axis displaced 30° from facing
7695-432: The possibility of a much warmer lunar mantle than previously believed, at least on the near side where the deep crust is substantially warmer because of the greater concentration of radioactive elements. Evidence has been found for 2–10 million years old basaltic volcanism within the crater Lowell, inside the Orientale basin. Some combination of an initially hotter mantle and local enrichment of heat-producing elements in
7790-439: The preexisting layer of target materials and therefore it form an inverted stratigraphy than the underlying bedrock. In some cases, the excavated fragment of ejects materials can form secondary craters . The materials of ejecta blanket come from rock fragments of crater excavation, materials due to impact melting, and outside the crater. Immediately after an impact event , the falling debris forms an ejecta blanket surrounding
7885-587: The prefix seleno- (as in selenography , the study of the physical features of the Moon) come from this Greek word. Artemis , the Greek goddess of the wilderness and the hunt, came to also be identified as the goddess of the Moon ( Selene ) and was sometimes called Cynthia , after her birthplace on Mount Cynthus . Her Roman equivalent is Diana . The names Luna, Cynthia, and Selene are reflected in technical terms for lunar orbits such as apolune , pericynthion and selenocentric . The astronomical symbol for
7980-436: The radius of the Moon. Its composition is not well understood, but is probably metallic iron alloyed with a small amount of sulfur and nickel; analyzes of the Moon's time-variable rotation suggest that it is at least partly molten. The pressure at the lunar core is estimated to be 5 GPa (49,000 atm). On average the Moon's surface gravity is 1.62 m/s ( 0.1654 g ; 5.318 ft/s ), about half of
8075-471: The regolith because of the Moon's gravity or are lost to space, either through solar radiation pressure or, if they are ionized, by being swept away by the solar wind's magnetic field. Studies of Moon magma samples retrieved by the Apollo missions demonstrate that the Moon had once possessed a relatively thick atmosphere for a period of 70 million years between 3 and 4 billion years ago. This atmosphere, sourced from gases ejected from lunar volcanic eruptions,
8170-435: The size of impact crater diameter. The low gravity and lack of atmosphere (air less bodies) favors the formation of the impact cratering and associated ejecta black on the surface of moon and Mercury. Although a thick atmosphere and relatively higher gravity of Venus reduce the likelihood impact cratering, the higher surface temperature augments the efficiency of the impact melting and associated ejecta deposits. Ejecta blanket
8265-436: The solid bodies of the solar system, the Earth rarely preserve the signature of impact ejecta blanket due to erosion. However, to date, there are 190 identified impact craters on the surface of Earth. Ejecta blankets have a diverse morphology. Variations in ejecta blanket indicates different geological characteristics involved with the impact cratering process such as nature of target materials and kinetic energy involved with
8360-435: The subfloor basalt. These basalt samples are composed primarily of plagioclase , but also contain amounts of clinopyroxene and other minerals . The unconsolidated regolith layer on the valley floor has a thickness of about 14 metres (46 ft) and contains ejecta from many impact event, most notably that which formed Tycho. Apollo 17 was thereby able to retrieve sample material from the Tycho impact without having to visit
8455-460: The surface gravity of Mars and about a sixth of Earth's. The Moon's gravitational field is not uniform. The details of the gravitational field have been measured through tracking the Doppler shift of radio signals emitted by orbiting spacecraft. The main lunar gravity features are mascons , large positive gravitational anomalies associated with some of the giant impact basins, partly caused by
8550-468: The timing and history of the Copernicus impact. Apollo mission planners ultimately selected Taurus–Littrow with the dual objectives of sampling ancient highland material and young volcanic material at the same landing site—the former in the form of Tycho ejecta, and the latter as a result the supposed volcanic origin of some of the valley floor's crater-like features. The Apollo 17 landing site within
8645-431: The valley is composed primarily of feldspar -rich breccia in the large massifs surrounding the valley and basalt underlying the valley floor, covered by an unconsolidated layer of mixed material formed by various geologic events. Taurus–Littrow was selected as the Apollo 17 landing site with the objectives of sampling highland material and young volcanic material at the same location. Several million years after
8740-401: The valley is subject to NASA's guidelines for the protection of Apollo lunar landing sites issued in 2011, which recommend keeping new exploration away from the vicinity of the aging Apollo 17 hardware that NASA has identified as historically significant. Aerospace company PTScientists announced in 2019 that its ALINA lunar lander was planned to land 3 to 5 km (1.9 to 3.1 mi) away from
8835-446: The winter solstice in the north polar crater Hermite . This is the coldest temperature in the Solar System ever measured by a spacecraft, colder even than the surface of Pluto . Blanketed on top of the Moon's crust is a highly comminuted (broken into ever smaller particles) and impact gardened mostly gray surface layer called regolith , formed by impact processes. The finer regolith, the lunar soil of silicon dioxide glass, has
8930-424: Was initially in hydrostatic equilibrium but has since departed from this condition. It has a geochemically distinct crust , mantle , and core . The Moon has a solid iron-rich inner core with a radius possibly as small as 240 kilometres (150 mi) and a fluid outer core primarily made of liquid iron with a radius of roughly 300 kilometres (190 mi). Around the core is a partially molten boundary layer with
9025-401: Was twice the thickness of that of present-day Mars . The ancient lunar atmosphere was eventually stripped away by solar winds and dissipated into space. A permanent Moon dust cloud exists around the Moon, generated by small particles from comets. Estimates are 5 tons of comet particles strike the Moon's surface every 24 hours, resulting in the ejection of dust particles. The dust stays above
#212787