Regolith (Greek: "blanket rock") is a layer of loose, heterogeneous material covering solid rock. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Heterogeneous is an adjective used to describe an object or system consisting of multiple items having a large number of structural variations In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids, and other planets. Dust is a general name for minute Solid particles with Diameters less than 500 micrometers. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is The term was first defined by George P. Merrill in 1897 who stated, "In places this covering is made up of material originating through rock-weathering or plant growth in situ. In other instances it is of fragmental and more or less decomposed matter drifted by wind, water or ice from other sources. This entire mantle of unconsolidated material, whatever its nature or origin, it is proposed to call the regolith. "^[1]

On the Earth

On Earth, the regolith is composed of four major subdivisions;

• Soil or pedolith
• Alluvium or recent unlithified transported cover
• Saprolith, generally divided into the
  • Upper saprolite: completely oxidised bedrock
  • Lower saprolite: chemically reduced partially weathered rocks
  • Saprock: fractured bedrock with weathering restricted to fracture margins. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel Alluvium (from the Latin, alluvius, from alluere, "to wash against" is Soil or Sediments deposited by a river or other running Saprolite (from Greek σαπρος =putrid + lite is the name for a chemically weathered rock Saprolite (from Greek σαπρος =putrid + lite is the name for a chemically weathered rock

In some instances, for example in the cratons, thin veneers of unconsolidated alluvium, colluvium or debris may be considered part of the regolith, especially if considerably younger than the basement or bedrock. A craton ( Greek kratos / κρἀτος ( neut. "strength" is an old and stable part of the Continental crust that has survived Alluvium (from the Latin, alluvius, from alluere, "to wash against" is Soil or Sediments deposited by a river or other running Colluvium is the name for loose bodies of Sediment that have been deposited or built up at the bottom of a low-grade slope or against a barrier on that slope transported by

The origins of regolith on Earth are weathering and biological processes; if it contains a significant proportion of biological compounds it is more conventionally referred to as soil. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Weathering is the decomposition of earth rocks, Soils and their Minerals through direct contact with the planet's Atmosphere. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel People also call various types of earthly regolith by such names as dirt, dust, gravel, sand, and (when wet) mud. Dust is a general name for minute Solid particles with Diameters less than 500 micrometers. Gravel is rock that is of a specific Particle size range In Geology, gravel is any loose rock that is larger than two millimeters (2mm Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles In computer gaming, a MUD ( Multi-User Dungeon, Domain or Dimension) is a multi-player computer game that combines elements of

On Earth, the presence of regolith is one of the important factors for most life, since few plants can grow on or within solid rock and animals would be unable to burrow or build shelter without loose material. Life is a state that distinguishes Organisms from non-living objects such as non-life and dead organisms being manifested by growth through Metabolism Plants are living Organisms belonging to the kingdom Plantae.

On the Moon

This famous image taken during Apollo 11 shows the fine and powdery texture of lunar soil.

Nearly the entire lunar surface is covered with regolith, bedrock being exposed only on very steep-sided crater walls and the occasional lava channel. Bedrock is the native consolidated rock underlying the surface of a terrestrial planet usually the Earth. This regolith has been formed over the last 4. 6 billion years by the impact of large and small meteoroids and the steady bombardment of micrometeoroids and solar and galactic charged particles breaking down surface rocks. A Micrometeoroid (also micrometeorite, micrometeor) is a tiny Meteoroid; a small particle of rock in space usually weighing less than a Gram

The impact of micrometeoroids, sometimes travelling faster than 60,000 mph (30 km/s), generates enough heat to melt or partially vaporize dust particles. This melting and refreezing welds particles together into glassy, jagged-edged agglutinates. ^[2]

The regolith is generally about 4-5 meters thick in mare areas and 10-15 m in older highland regions. The lunar maria (singular mare, two syllables are large dark Basaltic plains on Earth 's Moon, formed by ancient Volcanic eruptions ^[3] Below this true regolith is a region of blocky and fractured bedrock created by larger impacts which is often referred to as the "megaregolith".

The term lunar soil is often used interchangeably with "lunar regolith" but typically refers to the finer fraction of regolith, that which is composed of grains one centimeter in diameter or less. Lunar soil is the fine Regolith found on the surface of the Moon. Some have argued that the term "soil" is not correct in reference to the Moon because soil is defined as having organic content, whereas the Moon has none. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel Organic matter (or organic material) is Matter that has come from a once-living Organism; is capable of However, standard usage among lunar scientists is to ignore that distinction. "Lunar dust" generally connotes even finer materials than lunar soil, the fraction which is less than 30 micrometres in diameter.

The physical and optical properties of lunar regolith are altered through a process known as space weathering, which darkens the regolith over time, causing crater rays to fade and disappear. Space weathering is a blanket term used for a number of processes that act on any body exposed to the harsh space environment A ray system comprises the radial streaks of fine Ejecta thrown out during the formation of an Impact crater.

During the early phases of the Apollo Moon landing program, Thomas Gold of Cornell University and part of President's Science Advisory Committee raised a concern that the thick dust layer at the top of the regolith would not support the weight of the lunar module and that the module might sink beneath the surface. Thomas Gold ( May 22, 1920 &ndash June 22, 2004) was an Austrian born Astrophysicist, a professor of Astronomy In 1951 President of the United States Harry S Truman established the Science Advisory Committee as part of the Office of Defence Mobilization (ODM However, Joseph Veverka (also of Cornell) pointed out that Gold had miscalculated the depth of the overlying dust,^[4] which was only a couple of centimeters thick. Indeed, the regolith was found to be quite firm by the robotic Surveyor spacecraft that preceded Apollo, and during Apollo program the astronauts often found it necessary to use a hammer to drive a core sampling tool into it. The Surveyor Program was a NASA program that from 1966 through 1968 sent seven Robotic spacecraft to the surface of the Moon. A hammer is a tool meant to deliver an impact to an object The most common uses are for driving nails fitting parts and breaking up objects A core sample is a cylindrical section of a naturally occurring medium consistent enough to hold a layered structure

On Mars

Martian sand and boulders photographed by NASA's Mars Exploration Rover Spirit. NASA 's Mars Exploration Rover ( MER) Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of

Mars is covered with vast expanses of sand and dust and its surface is littered with rocks and boulders. The dust is occasionally picked up in vast planet-wide dust storms. Mars dust is very fine and enough remains suspended in the atmosphere to give the sky a reddish hue. The sand is believed to move only slowly in the martian winds due to the very low density of the atmosphere in the present epoch. In the past, liquid water flowing in gullies and river vallies may have shaped the martian regolith. Mars researchers are studying whether groundwater sapping is shaping the martian regolith in the present epoch, and whether carbon dioxide hydrates exist on Mars and play a role. Groundwater sapping is the geomorphic process in which Groundwater exits a bank or hillslope laterally as seeps and springs and erodes Carbon dioxide hydrate is a Type I gas Clathrate (Sloan 1998 However there has been some experimental evidence for the development It is believed that large quantities of water and carbon dioxide ices remain frozen within the regolith in the equatorial parts of Mars and on its surface at higher latitudes.

Regolith beneath NASA's Phoenix Mars Lander, where the descent thrusters have apparently cleared away several patches of soil to expose the underlying ice. Phoenix is a Robotic spacecraft on a Space exploration mission on Mars under the Mars Scout Program.

On asteroids

Taken from just 250 m above the surface of Eros as the NEAR Shoemaker spacecraft was landing, this image shows an area that is only 12 m across. The Near Earth Asteroid Rendezvous - Shoemaker (NEAR Shoemaker renamed after its launch in honor of planetary scientist Eugene M

Asteroids have regoliths developed by meteoroid impact. The final images taken by the NEAR Shoemaker spacecraft of the surface of Eros are the best images we have of an asteroidal regolith. The Near Earth Asteroid Rendezvous - Shoemaker (NEAR Shoemaker renamed after its launch in honor of planetary scientist Eugene M TemplateInfobox Planet. --> 433 Eros (ˈɪərɒs irr'-os) is the first discovered Near-Earth asteroid The recent Japanese Hayabusa mission also returned spectacular and surprising images of an asteroidal regolith on an asteroid so small it was thought that gravity was too low to develop and maintain a regolith. is an Unmanned space mission led by the Japan Aerospace Exploration Agency to return a sample of material from a small Near-Earth asteroid named

On Titan

Dunes on Titan's surface in a radar image taken by the Cassini spacecraft of a region approximately 160 by 325 kilometers (99 by 202 miles).

Pebbles on Titan's surface, imaged from a height of about 85 cm by the Huygens spacecraft.

Titan is known to have extensive fields of dunes, though the origin of the material forming the dunes is not known - it could be small fragments of water ice eroded by flowing methane, or possibly particulate organic matter that formed in Titan's atmosphere and rained down on the surface. TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as Scientists are beginning to call this loose icy material regolith because of the mechanical similarity with regolith on other bodies, although traditionally (and etymologically) the term had been applied only when the loose layer was composed of mineral grains like quartz or plagioclase or rock fragments that were in turn composed of such minerals. Mechanics ( Greek) is the branch of Physics concerned with the behaviour of physical bodies when subjected to Forces or displacements Etymology is the study of the History of Words &mdash when they entered a language from what source and how their form and meaning have changed over time A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Plagioclase is a very important series of tectosilicate Minerals within the Feldspar family Loose blankets of ice grains were not considered to be regolith because when they appear on Earth in the form of snow they behave differently than regolith, the grains melting and fusing with only small changes in pressure or temperature. "Snowfall" redirects here For other uses see Snow (disambiguation or Snowfall (disambiguation. The idea of an ice-regolith complete with erosion and aeolian and/or sedimentary processes is new to Titan because of its thermodynamic environment. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Aeolian (or Eolian or Æolian) processes pertain to the activity of the Winds and more specifically to the winds' ability to shape the surface of the Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of

The Huygens probe used a penetrometer on landing to characterize the mechanical properties of the local regolith. The Huygens probe, supplied by the European Space Agency (ESA and named after the Dutch 17th century astronomer Christiaan Huygens, is an atmospheric entry The surface itself was reported to be a clay-like "material which might have a thin crust followed by a region of relative uniform consistency. Clay is a naturally occurring material composed primarily of fine-grained Minerals which show plasticity through a variable range of Water content, and " Subsequent analysis of the data suggests that surface consistency readings were likely caused by Huygens displacing a large pebble as it landed, and that the surface is better described as a 'sand' made of ice grains. ^[5] The images taken after the probe's landing show a flat plain covered in pebbles. The pebbles, which may be made of water ice, are somewhat rounded, which may indicate the action of fluids on them. ^[6]

See also

• In-situ resource utilization
• Helium-3
• Soil
• Sand

External links

• Lunar Regolith and Fragmental Breccias

References