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Moon rock or lunar rock is rock originating from Earth's Moon. This includes lunar material collected during the course of human exploration of the Moon, and rock that has been ejected naturally from the Moon's surface and landed on Earth as meteorites.
Moon rocks on Earth come from four sources: those collected by six United States Apollo program crewed lunar landings from 1969 to 1972; those collected by three Soviet uncrewed Luna probes in the 1970s; those collected by the Chinese Lunar Exploration Program's uncrewed probes; and rocks that were ejected naturally from the lunar surface before falling to Earth as lunar meteorites.
Six Apollo missions collected 2,200 samples of material weighing 381 kilograms (840 lb), [1] processed into more than 110,000 individually cataloged samples. [2]
| Mission | Site | Sample mass returned [1] | Year |
|---|---|---|---|
| Apollo 11 | Mare Tranquillitatis | 21.55 kg (47.51 lb) | 1969 |
| Apollo 12 | Ocean of Storms | 34.30 kg (75.62 lb) | 1969 |
| Apollo 14 | Fra Mauro formation | 42.80 kg (94.35 lb) | 1971 |
| Apollo 15 | Hadley-Apennine | 76.70 kg (169.10 lb) | 1971 |
| Apollo 16 | Descartes Highlands | 95.20 kg (209.89 lb) | 1972 |
| Apollo 17 | Taurus-Littrow | 110.40 kg (243.40 lb) | 1972 |
Three Luna spacecraft returned with 301 grams (10.6 oz) of samples. [3] [4] [5]
| Mission | Site | Sample mass returned | Year |
|---|---|---|---|
| Luna 16 | Mare Fecunditatis | 101 g (3.6 oz) [6] | 1970 |
| Luna 20 | Mare Fecunditatis | 30 g (1.1 oz) [7] | 1972 |
| Luna 24 | Mare Crisium | 170 g (6.0 oz) [8] | 1976 |
The Soviet Union abandoned its attempts at a crewed lunar program in the 1970s, but succeeded in landing three robotic Luna spacecraft with the capability to collect and return small samples to Earth. A combined total of less than half a kilogram of material was returned.
In 1993, three small rock fragments from Luna 16, weighing 200 mg, were sold for US$ 442,500 at Sotheby's (equivalent to $896,417in 2022). [9] In 2018, the same three Luna 16 rock fragments sold for US$ 855,000 at Sotheby's. [10]
Chang'e 5, the fifth lunar exploration mission of the Chinese Lunar Exploration Program, returned with ~1,731 g (61.1 oz) of samples.
| Mission | Site | Sample mass returned | Year |
|---|---|---|---|
| Chang'e 5 | Mons Rümker | 1,731 g (3.8 lb) [11] | 2020 |
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More than 370 lunar meteorites have been collected on Earth, [12] representing more than 30 different meteorite finds (no falls), with a total mass of over 1,090 kilograms (2,400 lb). [13] Some were discovered by scientific teams (such as ANSMET) searching for meteorites in Antarctica, with most of the remainder discovered by collectors in the desert regions of northern Africa and Oman. A Moon rock known as "NWA 12691", which weighs 13.5 kilograms (30 lb), was found in the Sahara Desert at the Algerian and Mauritanian borders in January 2017, [14] and went on sale for $2.5 million in 2020. [15]
Rocks from the Moon have been measured by radiometric dating techniques. They range in age from about 3.16 billion years old for the basaltic samples derived from the lunar maria, up to about 4.44 billion years old for rocks derived from the highlands. [16] Based on the age-dating technique of "crater counting," the youngest basaltic eruptions are believed to have occurred about 1.2 billion years ago, [17] but scientists do not possess samples of these lavas. In contrast, the oldest ages of rocks from the Earth are between 3.8 and 4.28 billion years.
| Mineral | Elements | Lunar rock appearance |
|---|---|---|
| Plagioclase feldspar | Calcium (Ca) Aluminium (Al) Silicon (Si) Oxygen (O) | White to transparent gray; usually as elongated grains. |
| Pyroxene | Iron (Fe), Magnesium (Mg) Calcium (Ca) Silicon (Si) Oxygen (O) | Maroon to black; the grains appear more elongated in the maria and more square in the highlands. |
| Olivine | Iron (Fe) Magnesium (Mg) Silicon (Si) Oxygen (O) | Greenish color; generally, it appears in a rounded shape. |
| Ilmenite | Iron (Fe), Titanium (Ti) Oxygen (O) | Black, elongated square crystals. |
Moon rocks fall into two main categories: those found in the lunar highlands (terrae), and those in the maria. The terrae consist dominantly of mafic plutonic rocks. Regolith breccias with similar protoliths are also common. Mare basalts come in three distinct series in direct relation to their titanium content: high-Ti basalts, low-Ti basalts, and Very Low-Ti (VLT) basalts.
Almost all lunar rocks are depleted in volatiles and are completely lacking in hydrated minerals common in Earth rocks. In some regards, lunar rocks are closely related to Earth's rocks in their isotopic composition of the element oxygen. The Apollo Moon rocks were collected using a variety of tools, including hammers, rakes, scoops, tongs, and core tubes. Most were photographed prior to collection to record the condition in which they were found. They were placed inside sample bags and then a Special Environmental Sample Container for return to the Earth to protect them from contamination. In contrast to the Earth, large portions of the lunar crust appear to be composed of rocks with high concentrations of the mineral anorthite. The mare basalts have relatively high iron values. Furthermore, some of the mare basalts have very high levels of titanium (in the form of ilmenite). [19]
| Plagioclase | Pyroxene | Olivine | Ilmenite | |
|---|---|---|---|---|
| Anorthosite | 90% | 5% | 5% | 0% |
| Norite | 60% | 35% | 5% | 0% |
| Troctolite | 60% | 5% | 35% | 0% |
Primary igneous rocks in the lunar highlands compose three distinct groups: the ferroan anorthosite suite, the magnesian suite, and the alkali suite.
Lunar breccias, formed largely by the immense basin-forming impacts, are dominantly composed of highland lithologies because most mare basalts post-date basin formation (and largely fill these impact basins).
| Plagioclase | Pyroxene | Olivine | Ilmenite | |
|---|---|---|---|---|
| High titanium content | 30% | 54% | 3% | 18% |
| Low titanium content | 30% | 60% | 5% | 5% |
| Very low titanium content | 35% | 55% | 8% | 2% |
Mare basalts are named as such because they frequently constitute large portions of the lunar maria. These typically contain 18–21 percent FeO by weight, and 1–13 percent TiO2. They are similar to terrestrial basalts, but have many important differences; for example, mare basalts show a large negative europium anomaly. The type location is Mare Crisium sampled by Luna 24.
The main repository for the Apollo Moon rocks is the Lunar Sample Laboratory Facility at the Lyndon B. Johnson Space Center in Houston, Texas. For safekeeping, there is also a smaller collection stored at White Sands Test Facility in Las Cruces, New Mexico. Most of the rocks are stored in nitrogen to keep them free of moisture. They are handled only indirectly, using special tools.
Some Moon rocks from the Apollo missions are displayed in museums, and a few allow visitors to touch them. One of these, called the Touch Rock, is displayed in the Smithsonian National Air and Space Museum in Washington, D.C. [22] The idea of having touchable Moon rocks at a museum was suggested by Apollo scientist Farouk El-Baz, who was inspired by his childhood pilgrimage to Mecca where he touched the Black Stone (which in Islam is believed to be sent down from the heavens). [23]
Moon rocks collected during the course of lunar exploration are currently considered priceless. [22] In 2002, a safe was stolen from the Lunar Sample Building that contained minute samples of lunar and Martian material. The samples were recovered, and NASA estimated their value during the ensuing court case at about $1 million for 10 oz (280 g) of material.[ citation needed ]
Naturally transported Moon rocks in the form of lunar meteorites are sold and traded among private collectors.[ citation needed ]
Apollo 17 astronauts Eugene Cernan and Harrison Schmitt picked up a rock "composed of many fragments, of many sizes, and many shapes, probably from all parts of the Moon". This rock was later labeled sample 70017. [24] President Nixon ordered that fragments of that rock should be distributed in 1973 to all 50 US states and 135 foreign heads of state. The fragments were presented encased in an acrylic sphere, mounted on a wood plaque which included the recipients' flag which had also flown aboard Apollo 17. [25] Many of the presentation Moon rocks are now unaccounted for, having been stolen or lost.
Three minerals were discovered from the Moon: armalcolite, tranquillityite, and pyroxferroite. Armalcolite was named for the three astronauts on the Apollo 11 mission: Armstrong, Aldrin and Collins.
Because of their rarity on Earth, and the difficulty of obtaining more, Moon rocks have been frequent targets of theft and vandalism, and many have gone missing or were stolen.
Basalt is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a rocky planet or moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of Venus, which cover ~80% of the surface, are basaltic; the lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars.
Luna 16 was an uncrewed 1970 space mission, part of the Soviet Luna program. It was the first robotic probe to land on the Moon and return a sample of lunar soil to Earth. The 101 grams sample was returned from Mare Fecunditatis. It represented the first successful lunar sample return mission by the Soviet Union and was the third lunar sample return mission overall.
Luna 20 was the second of three successful Soviet lunar sample return missions. It was flown as part of the Luna program as a robotic competitor to the six successful Apollo lunar sample return missions.
Anorthite (an = not, ortho = straight) is the calcium endmember of the plagioclase feldspar mineral series. The chemical formula of pure anorthite is CaAl2Si2O8. Anorthite is found in mafic igneous rocks. Anorthite is rare on the Earth but abundant on the Moon.
Mare Cognitum is a lunar mare located in a basin or large crater which sits in the second ring of Oceanus Procellarum. To the northwest of the mare is the Montes Riphaeus mountain range, part of the rim of the buried crater or basin containing the mare. Previously unnamed, the mare received its name in 1964 in reference to its selection as the target for the successful impact probe Ranger 7, the first American spacecraft to return closeup images of the Moon's surface.
A lunar meteorite is a meteorite that is known to have originated on the Moon. A meteorite hitting the Moon is normally classified as a transient lunar phenomenon.
Anorthosite is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most commonly present.
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene. If olivine is present, the rock may be classified as an olivine nephelinite. Nephelinite is dark in color and may resemble basalt in hand specimen. However, basalt consists mostly of clinopyroxene (augite) and calcic plagioclase.
The Genesis Rock is a sample of Moon rock retrieved by Apollo 15 astronauts James Irwin and David Scott in 1971 during the second lunar EVA, at Spur crater. With a mass of c. 270 grams, it is currently stored at the Lunar Sample Laboratory Facility in Houston, Texas.
The Lunar Receiving Laboratory (LRL) was a facility at NASA's Lyndon B. Johnson Space Center that was constructed to quarantine astronauts and material brought back from the Moon during the Apollo program to reduce the risk of back-contamination. After recovery at sea, crews from Apollo 11, Apollo 12, and Apollo 14 walked from their helicopter to the Mobile Quarantine Facility on the deck of an aircraft carrier and were brought to the LRL for quarantine. Samples of rock and regolith that the astronauts collected and brought back were flown directly to the LRL and initially analyzed in glovebox vacuum chambers.
The geology of the Moon is quite different from that of Earth. The Moon lacks a true atmosphere, and the absence of free oxygen and water eliminates erosion due to weather. Instead, the surface is eroded much more slowly through the bombardment of the lunar surface by micrometeorites. It does not have any known form of plate tectonics, it has a lower gravity, and because of its small size, it cooled faster. In addition to impacts, the geomorphology of the lunar surface has been shaped by volcanism, which is now thought to have ended less than 50 million years ago. The Moon is a differentiated body, with a crust, mantle, and core.
A sample-return mission is a spacecraft mission to collect and return samples from an extraterrestrial location to Earth for analysis. Sample-return missions may bring back merely atoms and molecules or a deposit of complex compounds such as loose material and rocks. These samples may be obtained in a number of ways, such as soil and rock excavation or a collector array used for capturing particles of solar wind or cometary debris. Nonetheless, concerns have been raised that the return of such samples to planet Earth may endanger Earth itself.
The Lunar Magma Ocean (LMO) is the layer of molten rock that is theorized to have been present on the surface of the Moon. The Lunar Magma Ocean was likely present on the Moon from the time of the Moon's formation to tens or hundreds of millions of years after that time. It is a thermodynamic consequence of the Moon's relatively rapid formation in the aftermath of a giant impact between the proto-Earth and another planetary body. As the Moon accreted from the debris from the giant impact, gravitational potential energy was converted to thermal energy. Due to the rapid accretion of the Moon, thermal energy was trapped since it did not have sufficient time to thermally radiate away energy through the lunar surface. The subsequent thermochemical evolution of the Lunar Magma Ocean explains the Moon's largely anorthositic crust, europium anomaly, and KREEP material.
A lunar regolith simulant is a terrestrial material synthesized in order to approximate the chemical, mechanical, or engineering properties of, and the mineralogy and particle size distributions of, lunar regolith. Lunar regolith simulants are used by researchers who wish to research the materials handling, excavation, transportation, and uses of lunar regolith. Samples of actual lunar regolith are too scarce, and too small, for such research, and have been contaminated by exposure to Earth's atmosphere.
Taurus–Littrow is a lunar valley located on the near side at the coordinates 20.0°N 31.0°E. 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 a large object impacted the Moon, forming the Serenitatis basin and pushing rock outward and upward.
Hadley–Apennine is a region on the near side of Earth's Moon that served as the landing site for the American Apollo 15 mission, the fourth crewed landing on the Moon and the first of the "J-missions", in July 1971. The site is located on the eastern edge of Mare Imbrium on a lava plain known as Palus Putredinis. Hadley–Apennine is bordered by the Montes Apenninus, a mountain range, and Hadley Rille, a meandering channel, on the east and west, respectively.
Lunar Sample 61016, better known as "Big Muley", is a lunar sample discovered and collected on the Apollo 16 mission in 1972 in the Descartes Highlands, on the rim of Plum crater, near Flag crater. It is the largest sample returned from the Moon as part of the Apollo program. The rock, an 11.7 kg (26 lb) breccia consisting mainly of shocked anorthosite attached to a fragment of troctolitic "melt rock", is named after Bill Muehlberger, the Apollo 16 field geology team leader.
The Lunar basalt 70017 is a Moon rock gathered in 1972 by astronauts Eugene Cernan and Harrison Schmitt on the Apollo 17 mission near their Apollo Lunar Module and then divided into smaller pieces on Earth.
Allan Hills A81005 or ALH A81005 was the first lunar meteorite found on Earth. It was found in 1982 in the Allan Hills at the end of the Transantarctic Mountains, during a meteorite gathering expedition (ANSMET).
Lunar Sample 14321, better known as "Big Bertha", is a lunar sample containing an embedded Earth-origin meteorite collected on the 1971 Apollo 14 mission. It was found in the Fra Mauro region of the Moon. Big Bertha is the first discovered meteorite from Earth, and the embedded meteorite portion is the oldest known Earth rock. At 8.998 kg (19.84 lb), this breccia rock is the third largest Moon sample returned during the Apollo program, behind Big Muley and Great Scott.
The drill was deployed and penetrated to a depth of 35 cm before encountering hard rock or large fragments of rock. The column of regolith in the drill tube was then transferred to the soil sample container... the hermetically sealed soil sample container, lifted off from the Moon carrying 101 grams of collected material
Luna 20 was launched from the lunar surface on 22 February 1972 carrying 30 grams of collected lunar samples in a sealed capsule
the mission successfully collected 170.1 grams of lunar samples and deposited them into a collection capsule
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