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.
Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about nine times that of Earth. It has an eighth the average density of Earth, but is over 95 times more massive. Even though Saturn is almost as big as Jupiter, Saturn has less than a third the mass of Jupiter. Saturn orbits the Sun at a distance of 9.59 AU (1,434 million km), with an orbital period of 29.45 years.
Titan is the largest moon of Saturn and the second-largest in the Solar System. It is the only moon known to have an atmosphere denser than the Earth's and is the only known object in space—other than Earth—on which there is clear evidence that stable bodies of liquid exist. Titan is one of seven gravitationally rounded moons of Saturn and the second-most distant among them. Frequently described as a planet-like moon, Titan is 50% larger in diameter than Earth's Moon and 80% more massive. It is the second-largest moon in the Solar System after Jupiter's Ganymede and is larger than Mercury; yet Titan is only 40% as massive as Mercury, because Mercury is mainly iron and rock while much of Titan is ice, which is less dense.
Huygens was an atmospheric entry robotic space probe that landed successfully on Saturn's moon Titan in 2005. Built and operated by the European Space Agency (ESA), launched by NASA, it was part of the Cassini–Huygens mission and became the first spacecraft to land on Titan and the farthest landing from Earth a spacecraft has ever made. The probe was named after the 17th-century Dutch astronomer Christiaan Huygens, who discovered Titan in 1655.
An atmosphere is a layer of gases 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 colonization of Mars is the proposed process of establishing and maintaining control of Martian land for exploitation and the possible settlement of Mars. Most colonization concepts focus on settling, but colonization is a broader ethical concept, which international space law has limited, and national space programs have avoided, instead focusing on human mission to Mars for exploring the planet. The settlement of Mars would require the migration of humans to the planet, the establishment of a permanent human presence, and the exploitation of local resources.
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 exploration of Saturn has been solely performed by crewless probes. Three missions were flybys, which formed an extended foundation of knowledge about the system. The Cassini–Huygens spacecraft, launched in 1997, was in orbit from 2004 to 2017.
Whether there is life on Titan, the largest moon of Saturn, is currently an open question and a topic of scientific assessment and research. Titan is far colder than Earth, but of all the places in the Solar System, Titan is the only place besides Earth known to have liquids in the form of rivers, lakes, and seas on its surface. Its thick atmosphere is chemically active and rich in carbon compounds. On the surface there are small and large bodies of both liquid methane and ethane, and it is likely that there is a layer of liquid water under its ice shell. Some scientists speculate that these liquid mixes may provide prebiotic chemistry for living cells different from those on Earth.
The atmosphere of Titan is the dense layer of gases surrounding Titan, the largest moon of Saturn. Titan is the only natural satellite of a planet in the Solar System with an atmosphere that is denser than the atmosphere of Earth and is one of two moons with an atmosphere significant enough to drive weather. Titan's lower atmosphere is primarily composed of nitrogen (94.2%), methane (5.65%), and hydrogen (0.099%). There are trace amounts of other hydrocarbons, such as ethane, diacetylene, methylacetylene, acetylene, propane, PAHs and of other gases, such as cyanoacetylene, hydrogen cyanide, carbon dioxide, carbon monoxide, cyanogen, acetonitrile, argon and helium. The isotopic study of nitrogen isotopes ratio also suggests acetonitrile may be present in quantities exceeding hydrogen cyanide and cyanoacetylene. The surface pressure is about 50% higher than on Earth at 1.5 bars which is near the triple point of methane and allows there to be gaseous methane in the atmosphere and liquid methane on the surface. The orange color as seen from space is produced by other more complex chemicals in small quantities, possibly tholins, tar-like organic precipitates.
Lakes of liquid ethane and methane exist on the surface of Titan, Saturn's largest moon. This was confirmed by the Cassini–Huygens space probe, as had been suspected since the 1980s. The large bodies of liquid are known as maria (seas) and the small ones as lacūs (lakes).
The climate of Titan, the largest moon of Saturn, is similar in many respects to that of Earth, despite having a far lower surface temperature. Its thick atmosphere, methane rain, and possible cryovolcanism create an analogue, though with different materials, to the climatic changes undergone by Earth during the far shorter year of Earth.
Ligeia Mare is a lake in the north polar region of Titan, the planet Saturn's largest moon. It is the second largest body of liquid on the surface of Titan, after Kraken Mare. Larger than Lake Superior on Earth, it is mostly composed of liquid methane, with unknown but lesser components of dissolved nitrogen and ethane, as well as other organic compounds. It is located at 78° N, 249° W, and has been fully imaged by the Cassini spacecraft. Measuring roughly 420 km (260 mi) by 350 km (217 mi) across, it has a surface area of about 126,000 km2, and a shoreline over 2,000 km (1,240 mi) in length. The lake may be hydrologically connected to the larger Kraken Mare. Its namesake is Ligeia, one of the sirens in Greek mythology.
Titan Saturn System Mission (TSSM) was a joint NASA–ESA proposal for an exploration of Saturn and its moons Titan and Enceladus, where many complex phenomena were revealed by Cassini. TSSM was proposed to launch in 2020, get gravity assists from Earth and Venus, and arrive at the Saturn system in 2029. The 4-year prime mission would include a two-year Saturn tour, a 2-month Titan aero-sampling phase, and a 20-month Titan orbit phase.
Titan Mare Explorer (TiME) is a proposed design for a lander for Saturn's moon Titan. TiME is a relatively low-cost, outer-planet mission designed to measure the organic constituents on Titan and would have performed the first nautical exploration of an extraterrestrial sea, analyze its nature and, possibly, observe its shoreline. As a Discovery-class mission it was designed to be cost-capped at US$425 million, not counting launch vehicle funding. It was proposed to NASA in 2009 by Proxemy Research as a scout-like pioneering mission, originally as part of NASA's Discovery Program. The TiME mission design reached the finalist stage during that Discovery mission selection, but was not selected, and despite attempts in the U.S. Senate failed to get earmark funding in 2013. A related Titan Submarine has also been proposed.
Planetary oceanography, also called astro-oceanography or exo-oceanography, is the study of oceans on planets and moons other than Earth. Unlike other planetary sciences like astrobiology, astrochemistry, and planetary geology, it only began after the discovery of underground oceans in Saturn's moon Titan and Jupiter's moon Europa. This field remains speculative until further missions reach the oceans beneath the rock or ice layer of the moons. There are many theories about oceans or even ocean worlds of celestial bodies in the Solar System, from oceans made of liquid carbon with floating diamonds in Neptune to a gigantic ocean of liquid hydrogen that may exist underneath Jupiter's surface.
Vid Flumina is a river system of liquid methane and ethane on Saturn's moon Titan. It is more than 400 km (249 mi) long and flows into Titan's second largest hydrocarbon sea, Ligeia Mare. The surface of Titan is mostly water ice, so Vid Flumina is a river of methane and ethane flowing across and cutting canyons into ice as though it were bedrock. NASA scientists think that it likely has rapids, whirlpools and falls, just like rivers on Earth.
Titan Winged Aerobot (TWA) is a new aerobot exploration vehicle to enter the surface of Saturn's largest moon Titan. NASA has given this contract to Global Aerospace Corporation and Northrop Grumman collectively on July 6, 2016. Under the contract of 2016 NASA Small Business Innovation Research, both the teams will develop the TWA concept and produce a proof of concept prototype for Earth-based testing.
Dragonfly is a planned NASA mission to send a robotic rotorcraft to the surface of Titan, the largest moon of Saturn. It is planned to be launched in July 2028 and arrive in 2034. It would be the first aircraft on Titan and is intended to make the first powered and fully controlled atmospheric flight on any moon, with the intention of studying prebiotic chemistry and extraterrestrial habitability. It would then use its vertical takeoffs and landings (VTOL) capability to move between exploration sites.
Oceanus is a NASA/JPL orbiter mission concept proposed in 2017 for the New Frontiers mission #4, but it was not selected for development. If selected at some future opportunity, Oceanus would travel to Saturn's moon Titan to assess its habitability. Studying Titan would help understand the early Earth and exoplanets which orbit other stars. The mission is named after Oceanus, the Greek god of oceans.
