Tissint meteorite | |
---|---|
Type | Achondrite |
Class | Martian meteorite |
Group | Shergottite |
Country | Morocco |
Region | Tata Province, Guelmim-Es Semara |
Observed fall | Yes |
Fall date | 2011-07-18 |
TKW | 12 kilograms (26 lb)-15 kilograms (33 lb) |
Related media on Wikimedia Commons |
The Tissint meteorite is a Martian meteorite that fell in Tata Province in the Guelmim-Es Semara region of Morocco on July 18, 2011. Tissint is the fifth Martian meteorite that people have witnessed falling to Earth, and the first since 1962. [1] Pieces of the meteorite are on display at several museums, including the Museum of Natural History of Vienna and the Natural History Museum in London.
On July 18, 2011, around 2 AM local time, a bright fireball was observed by several people in the Oued Drâa valley, east of Tata, Morocco. One observer reported that the fireball was initially yellow in color, then turned green, illuminating the entire area before it appeared to break into two pieces; two sonic booms were heard over the valley.[ citation needed ]
In October 2011, nomads began to find very fresh, fusion-crusted stones in a remote area of the Oued Drâa intermittent watershed, centered about 50 kilometres (31 mi) ESE of Tata and 48 kilometres (30 mi) SSW of Tissint village, near the Oued El Gsaïb drainage and also near El Ga’ïdat plateau known as Hmadat Boû Rba’ine. The largest pieces were recovered in the El Ga’ïdat plateau, and the smallest ones (a few grams) were found closer to the El Aglâb mountains. One 47 g (1.7 oz) crusted stone was documented as found at 29°28.917’ N, 7°36.674’ W. [2]
Tissint was named after the town of Tissint, 48 kilometres (30 mi) away from the fall site. [3]
Up until 1990, only five meteorites had been found in Morocco, but since then, more meteorites have landed in the area. Current As of 2012 [update] records show that meteorite hunters have discovered 754 at specific sites in Morocco as well as thousands of others from uncertain locations. After the increases in meteorite falls, a market for meteorites drove the emergence of a meteorite prospecting industry in northwestern Africa and Oman. The rocks have been quickly brought out of the country into collections abroad because the significant discoveries resulted in high prices for the rocks (an auction on October 14, 2012, included fragments of the Tissent meteorite). [4] This made it difficult for researchers such as Hasnaa Chennaoui-Aoudjehane, the only one who has studied the meteorite, to have access to samples for her research and leaves Morocco with few remains of the meteorites that fell there. [5]
Dozens of fragments with masses ranging from 0.2 to 1,282 grams (0.0071 to 45.2212 oz) were collected, totaling roughly 12–15 kilograms (26–33 lb). The rocks are variably coated by a shining black fusion crust, characterized by thicker layers on exterior ridges and glossy regions above interior olivine phenocrysts and impact melt pockets. Some stones have a thinner secondary fusion crust on some surfaces, and some are broken in places, revealing the interior. The exposed interior of the stones appears pale green-grey in color, with mm-sized, pale yellow olivine phenocrysts with sparse vesicular pockets and thin veins of black glass. [2]
The meteorite was ejected from the surface of Mars between 700,000 and 1,1 million years ago. [6] Tissint appears to be derived from a deep mantle source region that was unlike any of the other known Martian shergottite meteorites. [6]
The material is highly shocked and indicates it was ejected during the largest impact excavation in record. [7] Given the widely dispersed shock melting observed in Tissint, alteration of other soft minerals (carbonates, halides, sulfates and even organics), especially along grain boundaries, might have occurred. This may in part explain the lack of such minerals in Tissint, [7] but it is unknown if it is of biotic origin. [8]
The meteorite fragments were recovered within days after the fall, so it is considered an "uncontaminated" meteorite. [9] The meteorite displays evidence of water weathering, and there are signs of elements being carried into cracks in the rocks by water or fluid, which is something never seen before in a Martian meteorite. [10] Specifically, scientists found carbon and nitrogen-containing compounds associated with hydrothermal mineral inclusions. [11] [8] One team reported measuring an elevated carbon-13 (13C) ratio, [12] while another team reported a low 13C ratio as compared to the content in Mars' atmosphere and crust, and suggested that it may be of biological origin, but the researchers also noted that there are several geological processes that could explain that without invoking complex life-processes; [8] for example, it could be of meteoritic origin and would have been mixed with Martian soil when meteorites and comets impact the surface of Mars, [8] or of volcanic origin. [13]
An analysis by Hasnaa Chennaoui-Aoudjehane, a Moroccan meteoriticist of Hassan II University in Casablanca, determined that the meteorite is a depleted picritic shergottite similar to EETA79001A. The internal structure of the meteorite includes olivine macrocrysts (or nodules) embedded into a fine-grained matrix made of pyroxene and feldspar glass. The matrix has numerous cracks filled with black glassy material. Like other shergottites Tissint meteorite is enriched in magnesium oxide and other compatible elements such as nickel and cobalt. The bulk composition is also depleted in light rare earths and other incompatible elements such as beryllium, lithium and uranium. However the glassy material is enriched in these elements. [12]
The data on refractory trace elements, sulfur and fluorine as well as the data on the isotopic composition of nitrogen, argon and carbon released upon heating from the matrix and glass veins in the meteorite unambiguously indicate the presence of a Martian surface component including trapped atmospheric gases. So, the influence of in situ Martian weathering can be distinguished from terrestrial contamination in the meteorite. The Martian weathering features in Tissint are compatible with the results of spacecraft observations of Mars, and Tissint has a cosmic ray dating exposure age of 0.7 ± 0.3 Ma—consistent with the reading of many other shergottites, notably EETA79001, suggesting that they were ejected from Mars during the same event. [12] [14]
The overall composition of the Tissint meteorite corresponds to that of aluminium-poor ferroan basaltic rock, which likely originated as a result of magmatic activity at the surface of Mars. These basalt then underwent weathering by fluids, which deposited minerals enriched in incompatible elements in fissures and cracks. A later impact on the surface of Mars melted the leached material forming black glassy veins. Finally shergottites were ejected from Mars about 0.7 million years ago. [12]
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.
The mineral olivine is a magnesium iron silicate with the chemical formula (Mg,Fe)2SiO4. It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickly on the surface. For this reason, olivine has been proposed as a good candidate for accelerated weathering to sequester carbon dioxide from the Earth's oceans and atmosphere, as part of climate change mitigation. Olivine also has many other historical uses, such as the gemstone peridot, as well as industrial applications like metalworking processes.
A Martian meteorite is a rock that formed on Mars, was ejected from the planet by an impact event, and traversed interplanetary space before landing on Earth as a meteorite. As of September 2020, 277 meteorites had been classified as Martian, less than half a percent of the 72,000 meteorites that have been classified. The largest complete, uncut Martian meteorite, Taoudenni 002, was recovered in Mali in early 2021. It weighs 14.5 kilograms and is on display at the Maine Mineral and Gem Museum.
In geology, the crust is the outermost solid shell of a planet, dwarf planet, or natural satellite. It is usually distinguished from the underlying mantle by its chemical makeup; however, in the case of icy satellites, it may be distinguished based on its phase.
Allan Hills 84001 (ALH84001) is a fragment of a Martian meteorite that was found in the Allan Hills in Antarctica on December 27, 1984, by a team of American meteorite hunters from the ANSMET project. Like other members of the shergottite–nakhlite–chassignite (SNC) group of meteorites, ALH84001 is thought to have originated on Mars. However, it does not fit into any of the previously discovered SNC groups. Its mass upon discovery was 1.93 kilograms (4.3 lb).
Adirondack is the nickname for Mars Exploration Rover Spirit's first target rock. Scientists chose Adirondack to be Spirit's first target rock after considering another, called Sashimi, that would have been a shorter, straight-ahead drive. Spirit traversed the sandy martian terrain at Gusev Crater to arrive in front of this football-sized rock on January 18, 2004, just three days after it successfully rolled off the lander.
The Thermal Emission Spectrometer (TES) is an instrument on board Mars Global Surveyor. TES collects two types of data, hyperspectral thermal infrared data from 6 to 50 micrometres (μm) and bolometric visible-NIR measurements. TES has six detectors arranged in a 2x3 array, and each detector has a field of view of approximately 3 × 6 km on the surface of Mars.
The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) was a visible-infrared spectrometer aboard the Mars Reconnaissance Orbiter searching for mineralogic indications of past and present water on Mars. The CRISM instrument team comprised scientists from over ten universities and was led by principal investigator Scott Murchie. CRISM was designed, built, and tested by the Johns Hopkins University Applied Physics Laboratory.
Martian soil is the fine regolith found on the surface of Mars. Its properties can differ significantly from those of terrestrial soil, including its toxicity due to the presence of perchlorates. The term Martian soil typically refers to the finer fraction of regolith. So far, no samples have been returned to Earth, the goal of a Mars sample-return mission, but the soil has been studied remotely with the use of Mars rovers and Mars orbiters.
The Aeolis quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Aeolis quadrangle is also referred to as MC-23 . The Aeolis quadrangle covers 180° to 225° W and 0° to 30° south on Mars, and contains parts of the regions Elysium Planitia and Terra Cimmeria. A small part of the Medusae Fossae Formation lies in this quadrangle.
Almost all water on Mars today exists as ice, though it also exists in small quantities as vapor in the atmosphere. What was thought to be low-volume liquid brines in shallow Martian soil, also called recurrent slope lineae, may be grains of flowing sand and dust slipping downhill to make dark streaks. While most water ice is buried, it is exposed at the surface across several locations on Mars. In the mid-latitudes, it is exposed by impact craters, steep scarps and gullies. Additionally, water ice is also visible at the surface at the north polar ice cap. Abundant water ice is also present beneath the permanent carbon dioxide ice cap at the Martian south pole. More than 5 million km3 of ice have been detected at or near the surface of Mars, enough to cover the whole planet to a depth of 35 meters (115 ft). Even more ice might be locked away in the deep subsurface. Some liquid water may occur transiently on the Martian surface today, but limited to traces of dissolved moisture from the atmosphere and thin films, which are challenging environments for known life. No evidence of present-day liquid water has been discovered on the planet's surface because under typical Martian conditions, warming water ice on the Martian surface would sublime at rates of up to 4 meters per year. Before about 3.8 billion years ago, Mars may have had a denser atmosphere and higher surface temperatures, potentially allowing greater amounts of liquid water on the surface, possibly including a large ocean that may have covered one-third of the planet. Water has also apparently flowed across the surface for short periods at various intervals more recently in Mars' history. Aeolis Palus in Gale Crater, explored by the Curiosity rover, is the geological remains of an ancient freshwater lake that could have been a hospitable environment for microbial life. The present-day inventory of water on Mars can be estimated from spacecraft images, remote sensing techniques, and surface investigations from landers and rovers. Geologic evidence of past water includes enormous outflow channels carved by floods, ancient river valley networks, deltas, and lakebeds; and the detection of rocks and minerals on the surface that could only have formed in liquid water. Numerous geomorphic features suggest the presence of ground ice (permafrost) and the movement of ice in glaciers, both in the recent past and present. Gullies and slope lineae along cliffs and crater walls suggest that flowing water continues to shape the surface of Mars, although to a far lesser degree than in the ancient past.
Seifertite is a silicate mineral with the formula SiO2 and is one of the densest polymorphs of silica. It has only been found in Martian and lunar meteorites, where it is presumably formed from either tridymite or cristobalite – other polymorphs of quartz – as a result of heating during the atmospheric re-entry and impact to the Earth, at an estimated minimal pressure of 35 GPa. It can also be produced in the laboratory by compressing cristobalite in a diamond anvil cell to pressures above 40 GPa. The mineral is named after Friedrich Seifert (born 1941), the founder of the Bayerisches Geoinstitut at University of Bayreuth, Germany, and is officially recognized by the International Mineralogical Association.
Nakhlites are a group of Martian meteorites, named after the first one, Nakhla meteorite.
The composition of Mars covers the branch of the geology of Mars that describes the make-up of the planet Mars.
Tissint is a small town near Tata, Morocco in Tata Province in the Souss-Massa region of Morocco. It has a population of 9,927 as of 2004.
Northwest Africa 7034 is a Martian meteorite believed to be the second oldest yet discovered. It is estimated to be two billion years old and contains the most water of any Martian meteorite found on Earth. Although it is from Mars it does not fit into any of the three SNC meteorite categories, and forms a new Martian meteorite group named "Martian ". Nicknamed "Black Beauty", it was purchased in Morocco and a slice of it was donated to the University of New Mexico by its American owner. The image of the original NWA 7034 was photographed in 2012 by Carl Agee, University of New Mexico.
Elephant Moraine 79001, also known as EETA 79001, is a Martian meteorite. It was found in Elephant Moraine, in the Antarctic during the 1979–1980 collecting season.
Allan Hills 77005 is a Martian meteorite that was found in the Allan Hills of Antarctica in 1977 by a Japanese National Institute of Polar Research mission team and ANSMET. Like other members of the group of SNCs, ALH-77005 is thought to be from Mars.
Astropedology is the study of very ancient paleosols and meteorites relevant to the origin of life and different planetary soil systems. It is a branch of soil science (pedology) concerned with soils of the distant geologic past and of other planetary bodies to understand our place in the universe. A geologic definition of soil is “a material at the surface of a planetary body modified in place by physical, chemical or biological processes”. Soils are sometimes defined by biological activity but can also be defined as planetary surfaces altered in place by biologic, chemical, or physical processes. By this definition, the question for Martian soils and paleosols becomes, were they alive? Astropedology symposia are a new focus for scientific meetings on soil science. Advancements in understanding the chemical and physical mechanisms of pedogenesis on other planetary bodies in part led the Soil Science Society of America (SSSA) in 2017 to update the definition of soil to: "The layer(s) of generally loose mineral and/or organic material that are affected by physical, chemical, and/or biological processes at or near the planetary surface and usually hold liquids, gases, and biota and support plants". Despite our meager understanding of extraterrestrial soils, their diversity may raise the question of how we might classify them, or formally compare them with our Earth-based soils. One option is to simply use our present soil classification schemes, in which case many extraterrestrial soils would be Entisols in the United States Soil Taxonomy (ST) or Regosols in the World Reference Base for Soil Resources (WRB). However, applying an Earth-based system to such dissimilar settings is debatable. Another option is to distinguish the (largely) biotic Earth from the abiotic Solar System, and include all non-Earth soils in a new Order or Reference Group, which might be tentatively called Astrosols.