Carbonates on Mars

Head (vessel) Evidence for carbonates on Mars was first discovered in 2008. Previously, most remote sensing instruments such as OMEGA and THEMIS—sensitive to infrared emissivity spectral features of carbonates—had not suggested the presence of carbonate outcrops,[1] at least at the 100 m or coarser spatial scales available from the returned data.[2]

Though ubiquitous, a 2003 study of carbonates on Mars showed that they are dominated by Magnesite (MgCO3) in Martian dust had mass fractions less than 5% and could have formed under current atmospheric conditions.[3] Furthermore, with the exception of the surface dust component, by 2007 carbonates had not been detected by any in situ mission, even though mineralogic modeling did not preclude small amounts of calcium carbonate in Independence class rocks of Husband Hill in Gusev crater[4] (note: An IAU naming convention within Gusev is not yet established).

PIA19816-Mars-EstimatingCarbon-Orbiters-20150902
Estimating carbon in the Nili Fossae plains region of Mars from orbiters (2 September 2015).

Remote sensing data

The first successful identification of a strong infrared spectral signature from surficial carbonate minerals of local scale (< 10 km²) was made by the MRO-CRISM team.[5] Spectral modeling in 2007 identified a key deposit in Nili Fossae dominated by a single mineral phase that was spatially associated with olivine outcrops. The dominant mineral appeared to be magnesite, while morphology inferred with HiRISE and thermal properties suggested that the deposit was lithic. Stratigraphically, this layer appeared between phyllosilicates below and mafic cap rocks above, temporally between the Noachian and Hesperian eras. Even though infrared spectra are representative of minerals to less than ≈0.1 mm depths[6] (in contrast to gamma spectra which are sensitive to tens of cm depths),[7] stratigraphic, morphologic, and thermal properties are consistent with the existence of the carbonate as outcrop rather than alteration rinds. Nevertheless, the morphology was distinct from typical terrestrial sedimentary carbonate layers suggesting formation from local aqueous alteration of olivine and other igneous minerals. However, key implications were that the alteration would have occurred under moderate pH and that the resulting carbonates were not exposed to sustained low pH aqueous conditions even as recently as the Hesperian. This increased the likelihood of local and regional scale geologic conditions on Mars that were favorable to analogs of terrestrial biological activity over geologically significant intervals.

As of 2012, the absence of more extensive carbonate deposits on Mars was thought by some scientists to be due to global dominance of low pH aqueous environments.[8] Even the least soluble carbonate, siderite (FeCO3), precipitates only at a pH greater than 5.[9][10]

Evidence for significant quantities of carbonate deposits on the surface began to increase in 2008 when the TEGA and WCL experiments on the 2007 Phoenix Mars lander found between 3–5wt% calcite (CaCO3) and an alkaline soil.[11] In 2010 analyses by the Mars Exploration Rover Spirit, identified outcrops rich in magnesium-iron carbonate (16–34 wt%) in the Columbia Hills of Gusev crater, most likely precipitated from carbonate-bearing solutions under hydrothermal conditions at near-neutral pH in association with volcanic activity during the Noachian era.[12]

After Spirit Rover stopped working scientists studied old data from the Miniature Thermal Emission Spectrometer, or Mini-TES and confirmed the presence of large amounts of carbonate-rich rocks, which means that regions of the planet may have once harbored water. The carbonates were discovered in an outcrop of rocks called "Comanche."[13][14]

Carbonates (calcium or iron carbonates) were discovered in a crater on the rim of Huygens Crater, located in the Iapygia quadrangle. The impact on the rim exposed material that had been dug up from the impact that created Huygens. These minerals represent evidence that Mars once had a thicker carbon dioxide atmosphere with abundant moisture. These kind of carbonates only form when there is a lot of water. They were found with the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on the Mars Reconnaissance Orbiter. Earlier, the instrument had detected clay minerals. The carbonates were found near the clay minerals. Both of these minerals form in wet environments. It is supposed that billions of years age Mars was much warmer and wetter. At that time, carbonates would have formed from water and the carbon dioxide-rich atmosphere. Later the deposits of carbonate would have been buried. The double impact has now exposed the minerals. Earth has vast carbonate deposits in the form of limestone.[15]

Gallery

Huygens Crater

Huygens Crater - circle shows location of carbonate deposit - representing a time when Mars had abundant liquid water on its surface (Scale bar = 259 km).

PIA19817-Mars-NiliFossae-CarbonateRichDeposit-20150902

Nili Fossae on Mars - largest known carbonate deposit.

See also

References

  1. ^ Bibring; Langevin, Y; Mustard, JF; Poulet, F; Arvidson, R; Gendrin, A; Gondet, B; Mangold, N; et al. (2006). "Global Mineralogical and Aqueous Mars History Derived from OMEGA/Mars Express Data". Science. 312 (5772): 400–404. Bibcode:2006Sci...312..400B. doi:10.1126/science.1122659. PMID 16627738.
  2. ^ Catling (2007). "Mars: Ancient fingerprints in the clay". Nature. 448 (7149): 31–32. Bibcode:2007Natur.448...31C. doi:10.1038/448031a. PMID 17611529.
  3. ^ Bandfield; et al. (2003). "Spectroscopic Identification of Carbonate Minerals in the Martian Dust". Science. 301 (5636): 1084–1087. Bibcode:2003Sci...301.1084B. doi:10.1126/science.1088054. PMID 12934004.
  4. ^ Clark; et al. (2007). "Evidence for montmorillonite or its compositional equivalent in Columbia Hills, Mars". Journal of Geophysical Research. 112 (E6): E06S01. Bibcode:2007JGRE..112.6S01C. doi:10.1029/2006JE002756.
  5. ^ Ehlmann; Mustard, JF; Murchie, SL; Poulet, F; Bishop, JL; Brown, AJ; Calvin, WM; Clark, RN; et al. (2008). "Orbital identification of carbonate-bearing rocks on Mars". Science. 322 (5909): 1828–1832. Bibcode:2008Sci...322.1828E. doi:10.1126/science.1164759. PMID 19095939.
  6. ^ Poulet; et al. (2007). "Martian surface mineralogy from Observatoire pour la Minéralogie, l'Eau, la Glace et l'Activité on board the Mars Express spacecraft (OMEGA/MEx): Global mineral maps". Journal of Geophysical Research: Planets. 112 (E8): E08S02. Bibcode:2007JGRE..112.8S02P. doi:10.1029/2006JE002840.
  7. ^ Boynton; et al. (2007). "Concentration of H, Si, Cl, K, Fe, and Th in the low- and mid-latitude regions of Mars". Journal of Geophysical Research: Planets. 112 (E12): E12S99. Bibcode:2007JGRE..11212S99B. doi:10.1029/2007JE002887.
  8. ^ Grotzinger, J. and R. Milliken (eds.) 2012. Sedimentary Geology of Mars. SEPM
  9. ^ Catling, David C. (1999-07-25). "A chemical model for evaporites on early Mars: Possible sedimentary tracers of the early climate and implications for exploration" (PDF). Journal of Geophysical Research. 104 (E7): 16453–16469. Bibcode:1999JGR...10416453C. doi:10.1029/1998JE001020. Archived (PDF) from the original on 2015-09-19.
  10. ^ Fairén, Alberto G.; Fernández-Remolar, David; Dohm, James M.; Baker, Victor R.; Amils, Ricardo (2004-09-23). "Inhibition of carbonate synthesis in acidic oceans on early Mars" (PDF). Nature. 431 (7007): 423–426. Bibcode:2004Natur.431..423F. doi:10.1038/nature02911. PMID 15386004. Archived (PDF) from the original on 2010-06-11.
  11. ^ Boynton, WV; Ming, DW; Kounaves, SP; Young, SM; Arvidson, RE; Hecht, MH; Hoffman, J; Niles, PB; et al. (2009). "Evidence for Calcium Carbonate at the Mars Phoenix Landing Site" (PDF). Science. 325 (5936): 61–64. Bibcode:2009Sci...325...61B. doi:10.1126/science.1172768. PMID 19574384. Archived (PDF) from the original on 2016-03-05.
  12. ^ Morris, RV; Ruff, SW; Gellert, R; Ming, DW; Arvidson, RE; Clark, BC; Golden, DC; Siebach, K; et al. (2010). "Identification of carbonate-rich outcrops on Mars by the Spirit rover" (PDF). Science. 329 (5990): 421–4. Bibcode:2010Sci...329..421M. doi:10.1126/science.1189667. PMID 20522738. Archived from the original (PDF) on 2011-07-25.
  13. ^ "Outcrop of long-sought rare rock on Mars found". sciencedaily.com. Archived from the original on 2017-09-07.
  14. ^ Richard V. Morris, Steven W. Ruff, Ralf Gellert, Douglas W. Ming, Raymond E. Arvidson, Benton C. Clark, D. C. Golden, Kirsten Siebach, Göstar Klingelhöfer, Christian Schröder, Iris Fleischer, Albert S. Yen, Steven W. Squyres. Identification of Carbonate-Rich Outcrops on Mars by the Spirit Rover. Science, June 3, 2010 doi:10.1126/science.1189667
  15. ^ "Some of Mars' Missing Carbon Dioxide May be Buried". NASA/JPL. Archived from the original on 2011-12-05.
Aeolis quadrangle

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 (Mars Chart-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.

The name refers to the name of a floating western island of Aiolos, the ruler of the winds. In Homer's account, Odysseus received the west wind Zephyr here and kept it in bags, but the wind got out.It is famous as the site of two spacecraft landings: the Spirit rover landing site (14.5718°S 175.4785°E / -14.5718; 175.4785) in Gusev crater (January 4, 2004), and the Curiosity rover in Gale Crater (4.591817°S 137.440247°E / -4.591817; 137.440247) (August 6, 2012).A large, ancient river valley, called Ma'adim Vallis, enters at the south rim of Gusev Crater, so Gusev Crater was believed to be an ancient lake bed. However, it seems that a volcanic flow covered up the lakebed sediments. Apollinaris Patera, a large volcano, lies directly north of Gusev Crater.Gale Crater, in the northwestern part of the Aeolis quadrangle, is of special interest to geologists because it contains a 2–4 km (1.2–2.5 mile) high mound of layered sedimentary rocks, named "Mount Sharp" by NASA in honor of Robert P. Sharp (1911–2004), a planetary scientist of early Mars missions. More recently, on 16 May 2012, "Mount Sharp" was officially named Aeolis Mons by the USGS and IAU.Some regions in the Aeolis quadrangle show inverted relief. In these locations, a stream bed may be a raised feature, instead of a valley. The inverted former stream channels may be caused by the deposition of large rocks or due to cementation. In either case erosion would erode the surrounding land but leave the old channel as a raised ridge because the ridge will be more resistant to erosion

Yardangs are another feature found in this quadrangle They are generally visible as a series of parallel linear ridges, caused by the direction of the prevailing wind.

Climate of Mars

The climate of the planet Mars has been a topic of scientific curiosity for centuries, in part because it is the only terrestrial planet whose surface can be directly observed in detail from the Earth with help from a telescope.

Although Mars is smaller than the Earth, 11% of Earth's mass, and 50% farther from the Sun than the Earth, its climate has important similarities, such as the presence of polar ice caps, seasonal changes and observable weather patterns. It has attracted sustained study from planetologists and climatologists. While Mars' climate has similarities to Earth's, including periodic ice ages, there are also important differences, such as much lower thermal inertia. Mars' atmosphere has a scale height of approximately 11 km (36,000 ft), 60% greater than that on Earth. The climate is of considerable relevance to the question of whether life is or was present on the planet. The climate briefly received more interest in the news due to NASA measurements indicating increased sublimation of one near-polar region leading to some popular press speculation that Mars was undergoing a parallel bout of global warming, although Mars' average temperature has actually cooled in recent decades, and the polar caps themselves are growing.

Mars has been studied by Earth-based instruments since the 17th century, but it is only since the exploration of Mars began in the mid-1960s that close-range observation has been possible. Flyby and orbital spacecraft have provided data from above, while landers and rovers have measured atmospheric conditions directly. Advanced Earth-orbital instruments today continue to provide some useful "big picture" observations of relatively large weather phenomena.

The first Martian flyby mission was Mariner 4, which arrived in 1965. That quick two-day pass (July 14–15, 1965) with crude instruments contributed little to the state of knowledge of Martian climate. Later Mariner missions (Mariner 6, and Mariner 7) filled in some of the gaps in basic climate information. Data-based climate studies started in earnest with the Viking program landers in 1975 and continue with such probes as the Mars Reconnaissance Orbiter.

This observational work has been complemented by a type of scientific computer simulation called the Mars general circulation model. Several different iterations of MGCM have led to an increased understanding of Mars as well as the limits of such models.

Compact Reconnaissance Imaging Spectrometer for Mars

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is a visible-infrared spectrometer aboard the Mars Reconnaissance Orbiter searching for mineralogic indications of past and present water on Mars. The CRISM instrument team comprises scientists from over ten universities and led by principal investigator Scott Murchie. CRISM was designed, built, and tested by the Johns Hopkins University Applied Physics Laboratory.

Composition of Mars

The composition of Mars covers the branch of the geology of Mars that describes the make-up of the planet Mars.

EETA 79001

EETA 79001, also known as Elephant Moraine 79001, is a Martian meteorite. It was found in Elephant Moraine, in the Antarctic during the 1979–1980 collecting season.

The meteorite is classified as a shergottite and is primarily basaltic in composition. EETA 79001 is the second largest Martian meteorite found on earth, at approximately 7900 grams, only the Zagami meteorite is larger. It is a very young rock, by geologic standards, dating to only about 180 million years ago, and was ejected from the Martian surface about 600 thousand years ago.

Geology of Mars

The geology of Mars is the scientific study of the surface, crust, and interior of the planet Mars. It emphasizes the composition, structure, history, and physical processes that shape the planet. It is analogous to the field of terrestrial geology. In planetary science, the term geology is used in its broadest sense to mean the study of the solid parts of planets and moons. The term incorporates aspects of geophysics, geochemistry, mineralogy, geodesy, and cartography. A neologism, areology, from the Greek word Arēs (Mars), sometimes appears as a synonym for Mars's geology in the popular media and works of science fiction (e.g. Kim Stanley Robinson's Mars trilogy).

Iapygia quadrangle

The Iapygia quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Iapygia quadrangle is also referred to as MC-21 (Mars Chart-21).The Iapygia quadrangle covers the area from 270° to 315° west longitude and from 0° to 30° south latitude on Mars. Parts of the regions Tyrrhena Terra and Terra Sabaea are found in this quadrangle. The largest crater in this quadrangle is Huygens. Some interesting features in this quadrangle are dikes,. the many layers found in Terby Crater, and the presence of carbonates on the rim of Huygens Crater.

Martian soil

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. On Earth, the term "soil" usually includes organic content. In contrast, planetary scientists adopt a functional definition of soil to distinguish it from rocks. Rocks generally refer to 10 cm scale and larger materials (e.g., fragments, breccia, and exposed outcrops) with high thermal inertia, with areal fractions consistent with the Viking Infrared Thermal Mapper (IRTM) data, and immobile under current aeolian conditions. Consequently, rocks classify as grains exceeding the size of cobbles on the Wentworth scale.

This approach enables agreement across Martian remote sensing methods that span the electromagnetic spectrum from gamma to radio waves. ‘‘Soil’’ refers to all other, typically unconsolidated, material including those sufficiently fine-grained to be mobilized by wind. Soil consequently encompasses a variety of regolith components identified at landing sites. Typical examples include: bedform armor, clasts, concretions, drift, dust, rocky fragments, and sand. The functional definition reinforces a recently proposed genetic definition of soil on terrestrial bodies (including asteroids and satellites) as an unconsolidated and chemically weathered surficial layer of fine-grained mineral or organic material exceeding centimeter scale thickness, with or without coarse elements and cemented portions.Martian dust generally connotes even finer materials than Martian soil, the fraction which is less than 30 micrometres in diameter. Disagreement over the significance of soil's definition arises due to the lack of an integrated concept of soil in the literature. The pragmatic definition "medium for plant growth" has been commonly adopted in the planetary science community but a more complex definition describes soil as "(bio)geochemically/physically altered material at the surface of a planetary body that encompasses surficial extraterrestrial telluric deposits." This definition emphasizes that soil is a body that retains information about its environmental history and that does not need the presence of life to form.

Sodium carbonate

Sodium carbonate, Na2CO3, (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, water-soluble salts. All forms have a strongly alkaline taste and give moderately alkaline solutions in water. Historically it was extracted from the ashes of plants growing in sodium-rich soils. Because the ashes of these sodium-rich plants were noticeably different from ashes of wood (once used to produce potash), sodium carbonate became known as "soda ash". It is produced in large quantities from sodium chloride and limestone by the Solvay process.

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