Water on MarsAlmost 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.
Atmosphere of MarsThe atmosphere of Mars is the layer of gases surrounding Mars. It is primarily composed of carbon dioxide (95%), molecular nitrogen (2.8%), and argon (2%). It also contains trace levels of water vapor, oxygen, carbon monoxide, hydrogen, and noble gases. The atmosphere of Mars is much thinner than Earth's. The average surface pressure is only about which is less than 1% of the Earth's value. The currently thin Martian atmosphere prohibits the existence of liquid water on the surface of Mars, but many studies suggest that the Martian atmosphere was much thicker in the past.
Exploration of MarsThe planet Mars has been explored remotely by spacecraft. Probes sent from Earth, beginning in the late 20th century, have yielded a large increase in knowledge about the Martian system, focused primarily on understanding its geology and habitability potential. Engineering interplanetary journeys is complicated and the exploration of Mars has experienced a high failure rate, especially the early attempts. Roughly sixty percent of all spacecraft destined for Mars failed before completing their missions and some failed before their observations could begin.
Martian meteoriteA 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. , 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 (32 pounds) and is on display at the Maine Mineral & Gem Museum.
Climate of MarsThe climate of 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.
MarsMars is the fourth planet and the furthest terrestrial planet from the Sun. The reddish color of its surface is due to finely grained iron(III) oxide dust in the soil, giving it the nickname "the Red Planet". Mars's radius is second smallest among the planets in the Solar System at . The Martian dichotomy is visible on the surface: on average, the terrain on Mars's northern hemisphere is flatter and lower than its southern hemisphere. Mars has a thin atmosphere made primarily of carbon dioxide and two irregularly shaped natural satellites: Phobos and Deimos.
Mars 2020Mars 2020 is a Mars rover mission that includes the rover Perseverance, the small robotic helicopter Ingenuity, and associated delivery systems, as part of NASA's Mars Exploration Program. Mars 2020 was launched from Earth on an Atlas V launch vehicle at 11:50:01 UTC on 30 July 2020, and confirmation of touch down in the Martian crater Jezero was received at 20:55 UTC on 18 February 2021. On 5 March 2021, NASA named the landing site of the rover Octavia E. Butler Landing.
AstrobiologyAstrobiology is a scientific field within the life and environmental sciences that studies the origins, early evolution, distribution, and future of life in the universe by investigating its deterministic conditions and contingent events. As a discipline, astrobiology is founded on the premise that life may exist beyond Earth. Research in astrobiology comprises three main areas: the study of habitable environments in the Solar System and beyond, the search for planetary biosignatures of past or present extraterrestrial life, and the study of the origin and early evolution of life on Earth.
BiosignatureA biosignature (sometimes called chemical fossil or molecular fossil) is any substance – such as an element, isotope, or molecule – or phenomenon that provides scientific evidence of past or present life. Measurable attributes of life include its complex physical or chemical structures and its use of free energy and the production of biomass and wastes. A biosignature can provide evidence for living organisms outside the Earth and can be directly or indirectly detected by searching for their unique byproducts.
Gale (crater)Gale is a crater, and probable dry lake, at in the northwestern part of the Aeolis quadrangle on Mars. It is in diameter and estimated to be about 3.5–3.8 billion years old. The crater was named after Walter Frederick Gale, an amateur astronomer from Sydney, Australia, who observed Mars in the late 19th century. Mount Sharp is a mountain in the center of Gale and rises high. Aeolis Palus is the plain between the northern wall of Gale and the northern foothills of Aeolis Mons.
Curiosity (rover)Curiosity is a car-sized Mars rover exploring Gale crater and Mount Sharp on Mars as part of NASA's Mars Science Laboratory (MSL) mission. Curiosity was launched from Cape Canaveral (CCAFS) on November 26, 2011, at 15:02:00 UTC and landed on Aeolis Palus inside Gale crater on Mars on August 6, 2012, 05:17:57 UTC. The Bradbury Landing site was less than from the center of the rover's touchdown target after a journey.
Mars in fictionMars, the fourth planet from the Sun, has appeared as a setting in works of fiction since at least the mid-1600s. Trends in the planet's portrayal have largely been influenced by advances in planetary science. It became the most popular celestial object in fiction in the late 1800s when it became clear that there was no life on the Moon. The predominant genre depicting Mars at the time was utopian fiction.
Phoenix (spacecraft)Phoenix was an uncrewed space probe that landed on the surface of Mars on May 25, 2008, and operated until November 2, 2008. Phoenix was operational on Mars for sols ( days). Its instruments were used to assess the local habitability and to research the history of water on Mars. The mission was part of the Mars Scout Program; its total cost was $420 million, including the cost of launch. The multi-agency program was led by the Lunar and Planetary Laboratory at the University of Arizona, with project management by NASA's Jet Propulsion Laboratory.
Rover (space exploration)A rover (or sometimes planetary rover) is a planetary surface exploration device designed to move across the solid surface on a planet or other planetary mass celestial bodies. Some rovers have been designed as land vehicles to transport members of a human spaceflight crew; others have been partially or fully autonomous robots. Rovers are typically created to land on another planet (other than Earth) via a lander-style spacecraft, tasked to collect information about the terrain, and to take crust samples such as dust, soil, rocks, and even liquids.
Viking lander biological experimentsIn 1976 two identical Viking program landers each carried four types of biological experiments to the surface of Mars. The first successful Mars landers, Viking 1 and Viking 2, then carried out experiments to look for biosignatures of microbial life on Mars. The landers each used a robotic arm to pick up and place soil samples into sealed test containers on the craft. The two landers carried out the same tests at two places on Mars' surface, Viking 1 near the equator and Viking 2 further north.
Perseverance (rover)Perseverance, nicknamed Percy, is a car-sized Mars rover designed to explore the Jezero crater on Mars as part of NASA's Mars 2020 mission. It was manufactured by the Jet Propulsion Laboratory and launched on July 30, 2020, at 11:50 UTC. Confirmation that the rover successfully landed on Mars was received on February 18, 2021, at 20:55 UTC. As of , Perseverance has been active on Mars for sols ( Earth days, or ) since its landing. Following the rover's arrival, NASA named the landing site Octavia E. Butler Landing.
Geology of MarsThe 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.
Extraterrestrial lifeExtraterrestrial life or alien life is life which may occur outside Earth and which did not originate on Earth. No extraterrestrial life has yet been conclusively detected. Such life might range from simple forms such as prokaryotes to intelligent beings, possibly bringing forth civilizations that might be far more advanced than humanity. The Drake equation speculates about the existence of sapient life elsewhere in the universe. The science of extraterrestrial life is known as astrobiology.
LithotrophLithotrophs are a diverse group of organisms using an inorganic substrate (usually of mineral origin) to obtain reducing equivalents for use in biosynthesis (e.g., carbon dioxide fixation) or energy conservation (i.e., ATP production) via aerobic or anaerobic respiration. While lithotrophs in the broader sense include photolithotrophs like plants, chemolithotrophs are exclusively microorganisms; no known macrofauna possesses the ability to use inorganic compounds as electron sources.
MethaneMethane (USˈmɛθeɪn , UKˈmiːθeɪn ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it poses technical challenges due to its gaseous state under normal conditions for temperature and pressure. Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes.
