page_title: Composition of Mars
section_title: Elemental composition
hierarchical_section_title: Composition of Mars / Elemental composition
caption_attribution_description: English: This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element silicon. Silicon is one of the most abundant elements on the surface of both Mars and Earth (second only to oxygen). The most extensive region of highest silicon content, shown in red, is located in the high latitudes north of Tharsis (centered near 45 degrees latitude, -120 degrees longitude). The area of lowest silicon content, shown in blue, lies just to the east of the Hellas Basin (-45 degrees latitude, 90 degrees longitude). Contours of constant surface elevation are also shown. The long continuous contour line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The gamma ray spectrometer was provided by the University of Arizona, Tucson. Lockheed Martin Astronautics, Denver, Colo., is the prime contractor for the project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.
context_page_description: The composition of Mars covers the branch of the geology of Mars that describes the make-up of the planet Mars.
context_section_description: Due to mars core it is differentiated, which—for a terrestrial planet—implies that it has a central core made up of metallic iron and nickel surrounded by a less dense, silicate mantle and crust. Like Earth, Mars appears to have a molten iron core, or at least a molten outer core. However, there does not appear to be convection in the mantle. Presently Mars shows little (if any) geological activity.
  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. The planet's distinctive red color is due to iron oxides on its surface. 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 are silicon, oxygen, 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.
caption: Elemental abundances can be determined remotely by orbiting spacecraft. This map shows the surface concentration (by weight percent) of the element silicon based on data from the Gamma Ray Spectrometer (GRS) Suite on the Mars Odyssey spacecraft. Similar maps exist for a number of other elements.
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