Composition of Mars

The composition of Mars covers the branch of the geology of Mars that describes the make-up of the planet Mars.Map of actual (and proposed) Rover landing sites including Gale Crater.Gale Crater - Landing site is within Aeolis Palus near Aeolis Mons ('Mount Sharp') - North is down.Gale Crater - Landing site is noted - also, alluvial fan (blue) and sediment layers in Aeolis Mons (cutaway).Curiosity rover landing site (green dot) - Blue dot marks Glenelg Intrigue - Blue spot marks 'Base of Mount Sharp' - a planned area of study.Curiosity rover landing site ('Bradbury Landing') viewed by HiRISE (MRO) (August 14, 2012).Aeolis Palus and 'Mount Sharp' in Gale Crater as viewed by the Curiosity rover (August 6, 2012).Layers at the base of Aeolis Mons - dark rock in inset is same size as the Curiosity rover (white balanced image).Gale Crater rim about 18 km (11 mi) North of the Curiosity rover (August 9, 2012).'Coronation' rock on Mars - first target of the ChemCam laser analyzer on the Curiosity rover (August 19, 2012).'Jake Matijevic' rock on Mars - a target of the APSX and ChemCam instruments on the Curiosity rover (September 22, 2012).'Bathurst Inlet' rock on Mars - as viewed by the MAHLI camera on the Curiosity rover (September 30, 2012).First-Year & First-Mile Traverse Map of the Curiosity rover on Mars (August 1, 2013) (3-D). The composition of Mars covers the branch of the geology of Mars that describes the make-up of the planet Mars. Like Earth, Mars is a differentiated planet, meaning that it has a central core made up of metallic iron and nickel surrounded by a less dense, silicate mantle and crust. The planet's distinctive red color is due to the oxidation of iron on its surface. The elemental composition of Mars is different from Earth's in several significant ways. First, Martian meteorite analysis suggests that the planet's mantle is about twice as rich in iron as the Earth's mantle. Second, its core is richer in sulphur. Third, the Martian mantle is richer in potassium and phosphorus than Earth's and fourth, the Martian crust contains a higher percentage of volatile elements such as sulphur and chlorine than the Earth's crust does. Many of these conclusions are supported by in situ analyses of rocks and soils on the Martian surface. Much of what we know about the elemental composition of Mars comes from orbiting spacecraft and landers. (See Exploration of Mars for list.) Most of these spacecraft carry spectrometers and other instruments to measure the surface composition of Mars by either remote sensing from orbit or in situ analyses on the surface. We also have many actual samples of Mars in the form of meteorites that have made their way to Earth. Martian meteorites (often called SNC's, for Shergottites, Nakhlites, and Chassignites—the groups of meteorites first shown to have a martian origin) provide data on the chemical composition of Mars' crust and interior that would not otherwise be available except through a sample return mission. Based on these data sources, scientists think that the most abundant chemical elements in the Martian crust, besides silicon and oxygen, are iron, magnesium, aluminum, calcium, and potassium. These elements are major components of the minerals comprising igneous rocks. The elements titanium, chromium, manganese, sulfur, phosphorus, sodium, and chlorine are less abundant but are still important components of many accessory minerals in rocks and of secondary minerals (weathering products) in the dust and soils (the regolith). On September 5, 2017, scientists reported that the Curiosity rover detected boron, an essential ingredient for life on Earth, on the planet Mars. Such a finding, along with previous discoveries that water may have been present on ancient Mars, further supports the possible early habitability of Gale Crater on Mars. Hydrogen is present as water (H2O) ice and in hydrated minerals. Carbon occurs as carbon dioxide (CO2) in the atmosphere and sometimes as dry ice at the poles. An unknown amount of carbon is also stored in carbonates. Molecular nitrogen (N2) makes up 2.7 percent of the atmosphere. As far as we know, organic compounds are absent except for a trace of methane detected in the atmosphere. On 16 December 2014, NASA reported the Curiosity rover detected a 'tenfold spike', likely localized, in the amount of methane in the Martian atmosphere. Sample measurements taken 'a dozen times over 20 months' showed increases in late 2013 and early 2014, averaging '7 parts of methane per billion in the atmosphere.' Before and after that, readings averaged around one-tenth that level. Mars is fundamentally an igneous planet. Rocks on the surface and in the crust consist predominantly of minerals that crystallize from magma. Most of our current knowledge about the mineral composition of Mars comes from spectroscopic data from orbiting spacecraft, in situ analyses of rocks and soils from six landing sites, and study of the Martian meteorites. Spectrometers currently in orbit include THEMIS (Mars Odyssey), OMEGA (Mars Express), and CRISM (Mars Reconnaissance Orbiter). The two Mars exploration rovers each carry an Alpha Particle X-ray Spectrometer (APXS), a thermal emission spectrometer (Mini-TES), and Mössbauer spectrometer to identify minerals on the surface. On October 17, 2012, the Curiosity rover on the planet Mars at 'Rocknest' performed the first X-ray diffraction analysis of Martian soil. The results from the rover's CheMin analyzer revealed the presence of several minerals, including feldspar, pyroxenes and olivine, and suggested that the Martian soil in the sample was similar to the 'weathered basaltic soils' of Hawaiian volcanoes. The dark areas of Mars are characterised by the mafic rock-forming minerals olivine, pyroxene, and plagioclase feldspar. These minerals are the primary constituents of basalt, a dark volcanic rock that also makes up the Earth's oceanic crust and the lunar maria.