Terraforming or terraformation ("Earth-shaping") is the hypothetical process of deliberately modifying the atmosphere, temperature, surface topography or ecology of a planet, moon, or other body to be similar to the environment of Earth to make it habitable for humans to live on.
An atmosphere is a layer of gasses that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosphere is the outer region of a star, which includes the layers above the opaque photosphere; stars of low temperature might have outer atmospheres containing compound molecules.
The possibility of life on Mars is a subject of interest in astrobiology due to the planet's proximity and similarities to Earth. To date, no proof of past or present life has been found on Mars. Cumulative evidence suggests that during the ancient Noachian time period, the surface environment of Mars had liquid water and may have been habitable for microorganisms, but habitable conditions do not necessarily indicate life.
The faint young Sun paradox or faint young Sun problem describes the apparent contradiction between observations of liquid water early in Earth's history and the astrophysical expectation that the Sun's output would be only 70 percent as intense during that epoch as it is during the modern epoch. The paradox is this: with the young Sun's output at only 70 percent of its current output, early Earth would be expected to be completely frozen, but early Earth seems to have had liquid water and supported life.
The atmosphere of Mars is the layer of gases surrounding Mars. It is primarily composed of carbon dioxide (95%), molecular nitrogen (2.85%), 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 610 pascals (0.088 psi) which is less than 1% of the Earth's value.
The terraforming of Mars or the terraformation of Mars is a hypothetical procedure that would consist of a planetary engineering project or concurrent projects aspiring to transform Mars from a planet hostile to terrestrial life to one that could sustainably host humans and other lifeforms free of protection or mediation. The process would involve the modification of the planet's extant climate, atmosphere, and surface through a variety of resource-intensive initiatives, as well as the installation of a novel ecological system or systems.
The terraforming of Venus or the terraformation of Venus is the hypothetical process of engineering the global environment of the planet Venus in order to make it suitable for human habitation. Adjustments to the existing environment of Venus to support human life would require at least three major changes to the planet's atmosphere:
- Reducing Venus's surface temperature of 737 K
- Eliminating most of the planet's dense 9.2 MPa (91 atm) carbon dioxide and sulfur dioxide atmosphere via removal or conversion to some other form
- The addition of breathable oxygen to the atmosphere.
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.
The 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 easily directly observed in detail from the Earth with help from a telescope.
Evidence for carbonates on Mars was first discovered in 2008. Carbonates were formed in the early history of Mars. Evidence shows Mars was once warmer and wet about 4 billion years ago, that is about 560 million years after the formation of Mars. At this time span, the water on early Mars reacted with Mars' carbon dioxide, this reaction formed carbonic acid. The carbonic acid joined into the water cycle on early Mars. The carbonic acid in the water cycle produced carbonates. The carbonates removed (leached) greenhouse gases, water vapor, and carbon dioxide from Mars' atmosphere.
Mars is the fourth planet from the Sun. The surface of Mars is orange-red because it is covered in iron(III) oxide dust, giving it the nickname "the Red Planet". Mars is among the brightest objects in Earth's sky and its high-contrast albedo features have make it a common subject for telescope viewing. It is classified as a terrestrial planet and is the second smallest of the Solar System's planets with a diameter of 6,779 km (4,212 mi). In terms of orbital motion, a Martian solar day (sol) is equal to 24.5 hours and a Martian solar year is equal to 1.88 Earth years. Mars has two natural satellites that are small and irregular in shape: Phobos and Deimos.
MAVEN is a NASA spacecraft orbiting Mars to study the loss of that planet's atmospheric gases to space, providing insight into the history of the planet's climate and water. The name is an acronym for "Mars Atmosphere and Volatile Evolution" while the word maven also denotes "a person who has special knowledge or experience; an expert". MAVEN was launched on an Atlas V rocket from Cape Canaveral Air Force Station, Florida, on 18 November 2013 UTC and went into orbit around Mars on 22 September 2014 UTC. The mission is the first by NASA to study the Mars atmosphere. The probe is analyzing the planet's upper atmosphere and ionosphere to examine how and at what rate the solar wind is stripping away volatile compounds.
The Mars ocean theory states that nearly a third of the surface of Mars was covered by an ocean of liquid water early in the planet's geologic history. This primordial ocean, dubbed Paleo-Ocean or Oceanus Borealis, would have filled the basin Vastitas Borealis in the northern hemisphere, a region which lies 4–5 km below the mean planetary elevation, at a time period of approximately 4.1–3.8 billion years ago. Evidence for this ocean includes geographic features resembling ancient shorelines, and the chemical properties of the Martian soil and atmosphere. Early Mars would have required a denser atmosphere and warmer climate to allow liquid water to remain at the surface.
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 carbonate–silicate geochemical cycle, also known as the inorganic carbon cycle, describes the long-term transformation of silicate rocks to carbonate rocks by weathering and sedimentation, and the transformation of carbonate rocks back into silicate rocks by metamorphism and volcanism. Carbon dioxide is removed from the atmosphere during burial of weathered minerals and returned to the atmosphere through volcanism. On million-year time scales, the carbonate-silicate cycle is a key factor in controlling Earth's climate because it regulates carbon dioxide levels and therefore global temperature.
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.
A planetary surface is where the solid or liquid material of certain types of astronomical objects contacts the atmosphere or outer space. Planetary surfaces are found on solid objects of planetary mass, including terrestrial planets, dwarf planets, natural satellites, planetesimals and many other small Solar System bodies (SSSBs). The study of planetary surfaces is a field of planetary geology known as surface geology, but also a focus on a number of fields including planetary cartography, topography, geomorphology, atmospheric sciences, and astronomy. Land is the term given to non-liquid planetary surfaces. The term landing is used to describe the collision of an object with a planetary surface and is usually at a velocity in which the object can remain intact and remain attached.
Planetary science is the scientific study of planets, celestial bodies and planetary systems and the processes of their formation. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation, interrelations and history. It is a strongly interdisciplinary field, which originally grew from astronomy and Earth science, and now incorporates many disciplines, including planetary geology, cosmochemistry, atmospheric science, physics, oceanography, hydrology, theoretical planetary science, glaciology, and exoplanetology. Allied disciplines include space physics, when concerned with the effects of the Sun on the bodies of the Solar System, and astrobiology.
The gravity of Mars is a natural phenomenon, due to the law of gravity, or gravitation, by which all things with mass around the planet Mars are brought towards it. It is weaker than Earth's gravity due to the planet's smaller mass. The average gravitational acceleration on Mars is 3.72076 ms−2 and it varies.
Life habitable zones, also called Habitable Zone for Complex Life (HZCL), are the known zones in a planetary system to support life. Life habitable zones are part of the planetary habitability study. Most zones have a start point at a distance from the host star and then an end point farther from the star. A planet or exoplanet would need to orbit inside the boundaries of this zone. With multiple zones, the zones would need to overlap for life. The requirements for only bacteria life produces a much larger zone, than for complex life, which requires a very narrow zone.
