Ganymede, Moon

Ganymede Union World, Jupiter Moon, Sol System

---

Populated and colonized since the early 22nd century, Ganymede is a vibrant diverse world and an industrial powerhouse mostly concentrating on heavy and ultra heavy industry. Steel, Aluminum. Copper and Ultronit products are manufactured in coninent sized factories, Steel mills and Metal smelters. Millions of tons of Scrap metal, ore and minerals are transported to Ganymede in many freighter loads every day. Heavy machinery, Space ship hull and frame components, Space Station components and building materials are exported. 1.1 Billion Inhabitants make Ganymede their home. Civics : Workers Council - Elected Representative at the Assembly, Civics :Union Laws, No Local Ordinances exist. There are two Class A Freight Space Ports. Ganymede is connected via TransMatter Tunnels to Sol Hub and is attached to the Sol Tram System. Capitol : Pioneer Ten Good Recreational facilities exist.

Ganymede /ˈɡænɨmiːd/ (Jupiter III) is a satellite of Jupiter and the largest moon in the Solar System. It is the seventh moon and third Galilean satellite outward from Jupiter. Completing an orbit in roughly seven days, Ganymede participates in a 1:2:4 orbital resonance with the moons Europa and Io, respectively. It has a diameter of 5,268 km (3,273 mi), 8% larger than that of the planet Mercury, but has only 45% of the latter's mass.[14] Its diameter is 2% larger than that of Titan, the second largest moon. It also has the highest mass of all planetary satellites, with 2.02 times the mass of the Earth's moon.

Ganymede is composed of approximately equal amounts of silicate rock and water ice. It is a fully differentiated body with an iron-rich, liquid core. A saltwater ocean is believed to exist nearly 200 km below Ganymede's surface, sandwiched between layers of ice. Its surface is composed of two main types of terrain. Dark regions, saturated with impact craters and dated to four billion years ago, cover about a third of the satellite. Lighter regions, crosscut by extensive grooves and ridges and only slightly less ancient, cover the remainder. The cause of the light terrain's disrupted geology is not fully known, but was likely the result of tectonic activity brought about by tidal heating.

Ganymede is the only satellite in the Solar System known to possess a magnetosphere, likely created through convection within the liquid iron core. The meager magnetosphere is buried within Jupiter's much larger magnetic field and would show only as a local perturbation of the field lines. The satellite has a thin oxygen atmosphere that includes O, O2, and possibly O3 (ozone). Atomic hydrogen is a minor atmospheric constituent. Whether the satellite has an ionosphere associated with its atmosphere is unresolved.

Ganymede's discovery is credited to Galileo Galilei, who was the first to observe it on January 7, 1610. The satellite's name was soon suggested by astronomer Simon Marius, for the mythological Ganymede, cupbearer of the Greek gods and Zeus's lover.Beginning with Pioneer 10, spacecraft have been able to examine Ganymede closely.[20] The Voyager probes refined measurements of its size, while the Galileo craft discovered its underground ocean and magnetic field. The next planned mission to the Jovian system is the European Space Agency's Jupiter Icy Moon Explorer (JUICE), due to launch in 2022. After flybys of all three icy Galilean moons the probe is planned to enter orbit around Ganymede. The Ganymedian surface is a mix of two types of terrain: very old, highly cratered, dark regions and somewhat younger (but still ancient), lighter regions marked with an extensive array of grooves and ridges. The dark terrain, which comprises about one-third of the surface, contains clays and organic materials that could indicate the composition of the impactors from which Jovian satellites accreted.

The heating mechanism required for the formation of the grooved terrain on Ganymede is an unsolved problem in the planetary sciences. The modern view is that the grooved terrain is mainly tectonic in nature.[5] Cryovulcanism is thought to have played only a minor role, if any. The forces that caused the strong stresses in the ganymedian ice lithosphere necessary to initiate the tectonic activity may be connected to the tidal heating events in the past, possibly caused when the satellite passed through unstable orbital resonances. The tidal flexing of the ice may have heated the interior and strained the lithosphere, leading to the development of cracks and horst and graben faulting, which erased the old, dark terrain on 70% of the surface. The formation of the grooved terrain may also be connected with the early core formation and subsequent tidal heating of the moon's interior, which may have caused a slight expansion of Ganymede by 1–6% due to phase transitions in ice and thermal expansion.During subsequent evolution deep, hot water plumes may have risen from the core to the surface, leading to the tectonic deformation of the lithosphere. Radiogenic heating within the satellite is the most relevant current heat source, contributing, for instance, to ocean depth. Research models have found that if the orbital eccentricity were an order of magnitude greater than currently (as it may have been in the past), tidal heating would be a more substantial heat source than radiogenic heating.

The craters Gula and Achelous (bottom), in the grooved terrain of Ganymede, with ejecta "pedestals" and rampartsCratering is seen on both types of terrain, but is especially extensive on the dark terrain: it appears to be saturated with impact craters and has evolved largely through impact events. The brighter, grooved terrain contains many fewer impact features, which have been only of a minor importance to its tectonic evolution.The density of cratering indicates an age of 4 billion years for the dark terrain, similar to the highlands of the Moon, and a somewhat younger age for the grooved terrain (but how much younger is uncertain). Ganymede may have experienced a period of heavy cratering 3.5 to 4 billion years ago similar to that of the Moon. If true, the vast majority of impacts happened in that epoch, while the cratering rate has been much smaller since. Craters both overlay and are crosscut by the groove systems, indicating that some of the grooves are quite ancient. Relatively young craters with rays of ejecta are also visible.Ganymedian craters are flatter than those on the Moon and Mercury. This is probably due to the relatively weak nature of Ganymede's icy crust, which can (or could) flow and thereby soften the relief. Ancient craters whose relief has disappeared leave only a "ghost" of a crater known as a palimpsest.

One significant feature on Ganymede is a dark plain named Galileo Regio, which contains a series of concentric grooves, or furrows, likely created during a period of geologic activity.

Ganymede also has polar caps, likely composed of water frost. The frost extends to 40° latitude.[26] These polar caps were first seen by the Voyager spacecraft. Theories on the caps' formation include the migration of water to higher latitudes and bombardment of the ice by plasma. Data from Galileo suggests the latter is correct. The presence of a magnetic field on Ganymede results in more intense charged particle bombardment of its surface in the unprotected polar regions; sputtering then leads to redistribution of water molecules, with frost migrating to locally colder areas within the polar terrain.

[[Category:G]]