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37-423: The Utopia basin is estimated to have formed around 4.3-4.1 billion years ago. The impactor was likely around 400–700 kilometres (250–430 mi) in diameter. The basin was subsequently mostly filled in, resulting in a mascon (a strong positive gravity anomaly ) detectable by orbiting satellites. Many rocks at Utopia Planitia appear perched, as if wind removed much of the soil at their bases. A hard surface crust

74-404: A mass concentration (or mascon ) is a region of a planet's or moon's crust that contains a large positive gravity 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 (compared to some suitable average), such as is found around Hawaii on Earth. However, this term is most often used to describe

111-526: A geologic structure that has a positive gravitational anomaly associated with a feature (e.g. depressed basin) that might otherwise have been expected to have a negative anomaly, such as the "mascon basins" on the Moon . The Moon is the most gravitationally "lumpy" major body known in the Solar System. Its largest mascons can cause a plumb bob to hang about a third of a degree off vertical, pointing toward

148-550: A large amount of underground ice in the Utopia Planitia region. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior . Scalloped topography is common in the mid-latitudes of Mars, between 45° and 60° north and south. It is particularly prominent in the region of Utopia Planitia in the northern hemisphere and in the region of Peneus and Amphitrites Patera in

185-724: A mantle layer, called latitude dependent mantle , that fell from the sky when the climate was different. In the Star Trek media franchise, Utopia Planitia—both on Mars' surface and a space station in areosynchronous orbit above it—is the site of a major United Federation of Planets shipyard, the Utopia Planitia Fleet Yards. Ships such as the USS Enterprise -D , USS Defiant , USS Voyager and USS Sao Paulo were built there. Mascon In astronomy , astrophysics and geophysics ,

222-642: A map of the Moon that names Mare Imbrium "Regio Magna Orientalis" (the Large Eastern Region). Michael van Langren 's 1645 map named it "Mare Austriacum" (the Austrian Sea). Mare Imbrium is visible to the naked eye from Earth. In the traditional ' Man in the Moon ' image seen on the Moon in Western folklore, Mare Imbrium forms the man's right eye. On 17 November 1970 at 03:47 Universal Time,

259-545: A positive gravitational anomaly. Since their identification in 1968 by Doppler tracking of the five Lunar Orbiter spacecraft, the origin of the mascons beneath the surface of the Moon has been subject to much debate, but they are 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 lunar orbits of satellites around

296-460: 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 that is currently 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

333-597: Is divided into several different ranges; the Montes Carpatus to the south, the Montes Apenninus to the southeast, and the Montes Caucasus to the east. At their highest, the outer ring of mountains rise more than 5 km above the surface of Mare Imbrium. The ring mountains are not as well developed to the north and west, and it appears they were simply not raised as high in these regions by

370-502: Is formed by solutions of minerals moving up through soil and evaporating at the surface. Some areas of the surface exhibit scalloped topography , a surface that looks like it was carved out by an ice cream scoop. This surface is thought to have formed by the degradation of an ice-rich permafrost. Many features that look like pingos on the Earth are found in Utopia Planitia (~35–50° N; ~80–115° E). On November 22, 2016, NASA reported finding

407-408: Is not as flat as it would have originally been when it first formed as a result of later events that have altered its surface. Mare Imbrium formed when a proto-planet from the asteroid belt collided with the Moon during the Late Heavy Bombardment . The impact is dated to approximately 3922 ± 12 million years ago, based on radiometric dating techniques. Ejecta from the impact covers large areas of

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444-542: The Apennine Mountains . Commander David Scott and Lunar Module Pilot James Irwin spent three days on the surface of the Moon, including 18½ hours outside the spacecraft on lunar extra-vehicular activity . Command Module Pilot Alfred Worden remained in orbit and acquired hundreds of high-resolution photographs of Mare Imbrium (and other regions of the Moon) as well as other types of scientific data. The crew on

481-522: The GRACE satellites . Mascons are often reported in terms of a derived physical quantity called "equivalent water thickness", "equivalent water height", or "water equivalent height", obtained dividing the surface mass density redistribution by the density of water . Mascons exist on Mercury . They were mapped by the MESSENGER spacecraft which orbited the planet from 2011 to 2015. Two are shown in

518-528: The Imbrium impact. The middle ring of mountains forms the Montes Alpes and Montes Archimedes . The innermost ring, with a diameter of 650 km, is defined by Montes Recti , Montes Teneriffe , and possibly Montes Spitzbergen . Much of this ring is submerged under the mare's basalt, resulting in only isolated peaks remaining in some areas, such as Mons Pico and Mons La Hire . Numerous estimates of

555-448: The Moon are unstable on a timescale of months or years. The small perturbations in the orbits accumulate and eventually distort the orbit enough for the satellite to impact the surface. 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 crewed lunar landing missions in 1971 and 1972;

592-417: The Moon's entire lithosphere . At the region of the Moon's surface exactly opposite Imbrium Basin, there is a region of chaotic terrain (the crater Van de Graaff ) which is thought to have been formed when the seismic waves of the impact were focused there after travelling through the Moon's interior. Mare Imbrium is about 750 miles (1,210 km) wide. A mass concentration (mascon), or gravitational high,

629-422: The Moon's surface by large projectiles blasted out of the basin at low angles, causing them to skim across the lunar surface ploughing out these features. The sculpture pattern was first identified by Grove Karl Gilbert in 1893. Furthermore, a Moon-wide pattern of faults which run both radial to and concentric to the Imbrium basin were thought to have been formed by the Imbrium impact; the event literally shattered

666-533: The Moon. While these lavas certainly contribute to the observed gravitational anomalies, uplift of the crust-mantle interface is also 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 that all the lunar mascons are super-isostatic (that is, supported above their isostatic positions). The huge expanse of mare basaltic volcanism associated with Oceanus Procellarum does not possess

703-507: The Soviet spacecraft Luna 17 made a soft landing in the mare, at latitude 38.28 N, and longitude 35.00 W. Luna 17 carried Lunokhod 1 , the first robotic rover to be deployed on the Moon or any extraterrestrial body. Lunokhod 1, a remote-controlled rover, was successfully deployed and undertook a mission lasting several months. In 1971, the crewed Apollo 15 mission landed in the southeastern region of Mare Imbrium, between Hadley Rille and

740-504: The Yutu rover 7 hours and 24 minutes later. Chang'e 3 mission attempted to perform the first direct measurement of the structure and depth of the lunar soil down to a depth of 30 m (98 ft), and investigate the lunar crust structure down to several hundred meters deep. The rover's ground penetrating radar found evidence of at least nine distinct rock layers , indicating that the area had surprisingly complex geological processes and

777-422: The accuracy of Project Apollo navigation were experiencing errors in predicted position of ten times the mission specification (2 kilometers instead of 200 meters). This meant that the predicted landing areas were 100 times as large as those being carefully defined for reasons of safety. Lunar orbital effects principally resulting from the strong gravitational perturbations of the mascons were ultimately revealed as

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814-754: The cause. William Wollenhaupt and Emil Schiesser of the NASA Manned Spacecraft Center in Houston then worked out the "fix" that was first applied to Apollo 12 and permitted its landing within 163 m (535 ft) 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. China's Chang’e 5T1 mission also mapped Moon's mascons. Mascons on Earth are often measured by means of satellite gravimetry , such as

851-479: The consistent 1:1 correlation between very 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

888-410: The depth of the mare material have been made using various methods. These include analyses of gravity, seismic, and radar data; studies of craters partially filled with basalt and those that have completely penetrated the mare; and comparisons of lunar basins filled with mare deposits to unfilled basins. These studies have yielded depth estimates ranging from 2 km to 5 km in the central part of

925-430: The giant crater to form the flat volcanic plain seen today. The basin's age has been estimated using uranium–lead dating methods to approximately 3.9 billion years ago, and the diameter of the impactor has been estimated to be 250 ± 25 km. The Moon's maria (plural of mare ) have fewer features than other areas of the Moon because molten lava pooled in the craters and formed a relatively smooth surface. Mare Imbrium

962-519: The image at right, at Caloris Planitia and at Sobkou Planitia . Mare Imbrium Mare Imbrium / ˈ ɪ m b r i ə m / ( Latin imbrium , the " Sea of Showers " or " Sea of Rains ") is a vast lava plain within the Imbrium Basin on the Moon and is one of the larger craters in the Solar System . The Imbrium Basin formed from the collision of a proto-planet during the Late Heavy Bombardment . Basaltic lava later flooded

999-508: The lunar gravitational field caused larger than expected perturbations, presumably 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 (JPL) in 1968 from a new analytic method applied to the highly precise navigation data from the uncrewed pre-Apollo Lunar Orbiter spacecraft. This discovery observed

1036-503: The mare may be "The Shrine of Hecate "; Plutarch records that the Ancient Greeks gave this name to the largest of the "hollows and deeps" on the Moon, believing it to be the place where the souls of the deceased were tormented. Ewen A. Whitaker argues that this likely refers to Mare Imbrium, "the largest regular-shaped dark area unbroken by bright patches" that can be seen with the naked eye. Around 1600, William Gilbert made

1073-437: The mare. It is thought that the original crater left by the Imbrium impact was as much as 100 km deep, but that the floor of the basin bounced back upwards immediately afterwards. Surrounding the Imbrium Basin is a region blanketed by ejecta from the impact, extending roughly 800 km outward. Also encircling the basin is a pattern of radial grooves called the "Imbrium Sculpture", which have been interpreted as furrows cut in

1110-515: The mascon, and increase the force of gravity by one-half percent. Typical examples of mascon basins on the Moon are the Imbrium , Serenitatis , Crisium and Orientale impact basins, all of which exhibit significant topographic depressions and positive gravitational anomalies. Examples of mascon basins on Mars are the Argyre , Isidis , and Utopia basins. Theoretical considerations imply that

1147-399: The near side of the Moon. With a diameter of 1145 km, Mare Imbrium is second only to Oceanus Procellarum in size among the maria, and it is the largest mare associated with an impact basin. The Imbrium Basin is surrounded by three concentric rings of mountains, uplifted by the colossal impact event that excavated it. The outermost ring of mountains has a diameter of 1300 km and

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1184-525: The removal of subsurface material, possibly interstitial ice, by sublimation . This process may still be happening at present. Polygonal, patterned ground is quite common in some regions of Mars. It is commonly believed to be caused by the sublimation of ice from the ground. Sublimation is the direct change of solid ice to a gas. This is similar to what happens to dry ice on the Earth. Places on Mars that display polygonal ground may indicate where future colonists can find water ice. Patterned ground forms in

1221-510: The rille wall. On 17 March 2013, an object hit the lunar surface in Mare Imbrium and exploded in a flash of apparent magnitude 4. The resulting crater was 18 meters wide. This was the brightest impact recorded since NASA's lunar impact team began monitoring in 2005. Chang'e 3 landed on 14 December 2013 on Mare Imbrium, about 40 km south of the 6 km diameter Laplace F crater, at 44.1260°N 19.5014°W. The lander deployed

1258-482: The southern hemisphere. Such topography consists of shallow, rimless depressions with scalloped edges, commonly referred to as scalloped depressions or simply scallops . Scalloped depressions can be isolated or clustered and sometimes seem to coalesce. A typical scalloped depression displays a gentle equator-facing slope and a steeper pole-facing scarp. This topographic asymmetry is probably due to differences in insolation . Scalloped depressions are believed to form from

1295-453: The subsatellite PFS-2 released from Apollo 16 was expected to stay in orbit for one and a half years, but lasted only 35 days before crashing into the lunar surface since it had to be deployed in a much lower orbit than initially planned. It was only in 2001 that the mascons were mapped and the frozen orbits were discovered. The Luna 10 orbiter was the first artificial object to orbit the Moon, and it returned tracking data indicating that

1332-429: The surface explored the area using the first lunar rover and returned to Earth with 77 kilograms (170 lb) of lunar surface material. Samples were collected from Mons Hadley Delta , believed to be a fault block of pre-Imbrian ( Nectarian or Pre-Nectarian ) lunar crust, including the " Genesis Rock ." This was also the only Apollo mission to visit a lunar rille, and to observe outcrops of lunar bedrock visible in

1369-451: Was identified in the center of Mare Imbrium from Doppler tracking of the five Lunar Orbiter spacecraft in 1968. The Imbrium mascon is the largest on the Moon. It was confirmed and mapped at higher resolution with later orbiters such as Lunar Prospector and GRAIL . Like most of the other maria on the Moon, Mare Imbrium was named by Giovanni Riccioli , whose 1651 nomenclature system has become standardized. The earliest known name for

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