User:Paleorthid/What is soil

1914 Definition
The different forms of earth on the surface of the rocks, formed by the breaking down or weathering of rocks. The soils will vary with the minerals in the rocks, the principle ones being quartz, felspar, clays, mica and limestone. When the soil is made from the rocks in the original position, they are called sedimentary (!); but if formed from rocks above them and carried to them theyare known as transported soils. When the soil is carried by glaciers, it forms drift soils; when carried by running water, it is known as alluvial soil. They are also known as clays, loams etc. Plants also make soil by their decay. So do animals, especially earthworms (q. v.) A mixed soil or loam is usually better than a clay or a sandy soil. The plants in the soil take from it 200 to 600 pounds per acre yearly of the minerals found in it, and the passage of water through it also carries away other quantities, so that, when crops are removed, the soil would gradually lose its power of supporting plant life were it not enriched. This is done naturally by the gradual decomposition of the minerals composing the soil, and also of the artificial process of applying manures and other fertilizers. Another mode of overcoming the difficulty to some extent is by changing the crops grown, as different crops take up the ingredients of the soil in different proportions. Agricultural scientists are constantly studying soils.

Source: Soil in The New Student's Reference Book for Teachers, Students and Families, Edited by Chandler B. Beach, A.M. Associate Editor Frank Morton McMurry, Ph.D. Chicago F. E. Compton and Company 1914

Banin's recent call to redefine soil
Banin, Amos, 2005. The Enigma of the Martian Soil, Science, Vol. 309. no. 5736, pp. 888 - 890 (5 August 2005) DOI: 10.1126/science.1112794

Some opportunities will also force us to broaden and even redefine the scope of our science. Banin (2005), in a noteworthy paper on Martian soils, adopts a definition of soils that does not explicitly include plants or other life forms, contrary to the definition used by the majority of soil scientists during the past century (Bockheim et al., 2005) and still held onto by some (Lin, 2005).



Banin, Amos, 2005. The Enigma of the Martian Soil, Science, Vol. 309. no. 5736, pp. 888 - 890 (5 August 2005) DOI: 10.1126/science.1112794

Comments on the above article:

What is a soil? On Earth, this term refers to the top layer of fine-grained, weathered material, which has been modified by atmospheric, hydrolytic, and biotic effects. Because terrestrial soils contain organic carbon and have been produced at least in part by the activity of soil microbes, it has been argued that this term does not apply on Mars. However, the concept of soil is still valuable. The MER science team has Mars soil as "any loose, unconsolidated materials" as opposed to rocks. On Mars, as on Earth, the most important attributes of soil are that it is broken up and chemically modified by weathering.

Banin suggests that martian soils can be defined analogously to terrestrial soils, as the top non-consolidated layer of weathered or partly weathered material that has been exposed to atmospheric or hydrologic effects. To date, we have no evidence to suggest biotic agents on Mars.

Banin calls the Atacama Desert a unique spot on Earth. He suggests that the scientific community should control and preserve sections of this environment for future studies. Thus preserved, we may use it as a testing ground for sterilization and quarantine protocols for Mars missions as well as studying it for what we can learn here about the history of the soil on Mars.soil is essential.

Source: Digging in the Dirt on Mars

Some opportunities will also force us to broaden and even redefine the scope of our science. Banin (2005), in a noteworthy paper on Martian soils, adopts a definition of soils that does not explicitly include plants or other life forms, contrary to the definition used by the majority of soil scientists during the past century (Bockheim et al., 2005) and still held onto by some (Lin, 2005).

Baveye, P., A.R. Jacobson, S.E. Allaire, J. Tandarich, and R. Bryant, 2006, Whither goes soil science in the US and Canada? Survey results and analysis. Soil Science (in press).

General
But why not just this: Soil is where ever organisms live & die in or upon earth material. Source: Dirt #2

Popular treatment
A definition consistent with Amos Banin's has been in use by the popular press since at least 1970: Mar. 30, 1970: When scientists selected some bacteria for experimental exposure to moon soil brought back by Apollo astronauts... Source: Time Magazine: Menace in Moon Soil?

But why not just this: Soil is where ever organisms live & die in or upon earth material. Source: Dirt #2

Scientific treatment
Discussions on moon soil exclusive of the term regolith are in common use by the scientific community: Soil mechanics is the study of the mechanical properties of soils and the way that these properties affect human activities. Soil mechanics studies were performed on all six of the Apollo Moon landings. The goals of these studies were to improve our scientific knowledge about the properties of lunar soil and to provide the engineering knowledge needed to plan and perform lunar surface activities.

Soil mechanics studies took a variety of forms. These included crew commentary while collecting geologic samples and deploying experiments and postmission analysis of photography of these activities. Several experiments were performed specifically to study soil mechanics. These include use of penetrometers, which are rods that measure the force required to penetrate to various depths in the soil. Also, several small trenches were dug to study the soil properties along the trench walls. Finally, studies were performed on samples returned to Earth. For example, analysis of core tubes allowed properties such as density, average grain size, strength, and compressibility to be measured as a function of depth.

During landing, the impact of rocket exhaust with the surface produced dust clouds. On some missions, dust became visible 30 to 50 meters above the surface, and during the final 10 to 20 meters of descent, the surface was largely obscured by the dust cloud. On other missions, the dust cloud was not as dense and the surface remained clearly visible throughout the landing.

The soil on the Moon is very fine-grained, with more than half of all grains being dust particles less than 0.1 millimeters across. Some of these particles become electrostatically charged and cling to objects (such as space suits and other equipment) that they come in contact with. The dark dust grains absorb sunlight, and equipment that became dust-coated sometimes became excessively hot. Despite the fine-grained nature of the surface, it provided good traction for astronauts as they moved about. Crew mobility, both on foot and in the lunar rover, was affected more by local topography such as craters and ridges than by soil properties.

The lunar surface easily supported the weight of the astronauts and their equipment. Typically, astronaut boots and the lunar rover's wheels only penetrated 1 to 2 centimeters into the surface, with penetration reaching five centimeters in some places. The lunar module footpads sank 2 to 20 centimeters into the soil. When astronauts inserted sampling tubes into the soil, they typically found penetration was easy for the first 10 to 20 centimeters and increasingly difficult below that depth. The deepest penetration achieved on a hand-driven core tube was 70 centimeters, which required about 50 blows with a hammer. For sampling at greater depths, the Apollo 15, 16, and 17 crews used a battery-powered drill. This allowed sampling to depths of 1.5 to 3 meters, which was achieved easily on Apollo 16 but with much more difficulty on Apollo 15 and 17.

Source: Apollo 17 Soil Mechanics Investigation

Taking Soil Science to Outer Space The answer to the question about life on Mars may very well come from analyzing an unsuspecting source—the soil, specifically the icy layer of soil underneath the red planet’s surface. By analyzing the properties of Mars’ frozen layer of soil during NASA’s next lander mission, scientists will be able to better understand and theorize about life on Mars.

A synopsis of the project will be presented by Douglas R. Cobos, Ph.D., on Monday, July 10, 2006, during the 18th World Congress of Soil Science in Philadelphia.

By exposing this frozen soil layer to the sun, researchers are hopeful to measure the properties of the liquid water before it turns to a vapor. According to Cobos, the discovery of this liquid water would be a “big finding and best case scenario for the Martian research community.” This liquid water – the pre-cursor for life says Cobos – could even point to “life in a dormant state on Mars.”

Cobos is a research scientist and engineer at Decagon Devices, Pullman, WA. NASA is working with Decagon, a soil science equipment manufacturer, on designing a probe to take soil and atmospheric measurements during the Phoenix 2007 Scout Mission. Galon Campbell, founder of the company and a soil scientist, designed the probe and, together with Cobos and Colin Campbell, is a co-author of the paper being presented in Philadelphia during the international World Congress of Soil Science.

Cobos said the physics on Mars is such that ice tends to go directly from the solid form into a vapor.

“If we can measure this liquid water using our specialized sensor mounted on the robotic arm of the lander, we’ll be able to turn over the data to the planetary scientists to analyze the climate and conditions on Mars,“ says Cobos. These scientists will use the data to determine if life ever arose on Mars or if it could sustain life in the future.

“We’re waiting to see what’s up there. The best-case scenario would be to dig, probe around and finally have conclusive proof that there can be liquid water on Mars,“ he says. “It’s pretty exciting to actually have our sensor bolted to the arm of the lander.”

Cobos, who has been working on the lander’s sensor for two years, just returned from the Jet Propulsion Lab where they mounted the sensor to the arm of the lander and calibrated it. The Phoenix Lander is planned to take off in late 2007 and arrive on Mars to begin its discoveries in early 2008.

Source: Soil Science Society of America

Moon soil ref #1 (pdf) Moon soil ref #2 Oxygen Generation from Synthetic Moon Soil Using a Plasma Reactor The surface of the moon is mostly covered with regolith, a mixture of fine dust and rocky debris made by meteor impacts. Regolith can be called the "soil" of the Moon. The look and feel of regolith is different from place to place on the Moon and is deeper in some places than in others.

Source: Soil on the Moon
 * 1) 9. Moon soil is called regolith.
 * 2) 10. The upper few hundred meeters of the Moon's surface is believed to be rubble that was generated by eons of meteor bombardment.

(Note: Meteor bombardment meets the definition of mechanical weathering. It, like the grinding action of glaciers, is a soil forming process)

source: Moon Factoids Soil mechanics is the study of the mechanical properties of soils and the way that these properties affect human activities. Soil mechanics studies were performed on all six of the Apollo Moon landings. The goals of these studies were to improve our scientific knowledge about the properties of lunar soil and to provide the engineering knowledge needed to plan and perform lunar surface activities.

Soil mechanics studies took a variety of forms. These included crew commentary while collecting geologic samples and deploying experiments and postmission analysis of photography of these activities. Several experiments were performed specifically to study soil mechanics. These include use of penetrometers, which are rods that measure the force required to penetrate to various depths in the soil. Also, several small trenches were dug to study the soil properties along the trench walls. Finally, studies were performed on samples returned to Earth. For example, analysis of core tubes allowed properties such as density, average grain size, strength, and compressibility to be measured as a function of depth.

During landing, the impact of rocket exhaust with the surface produced dust clouds. On some missions, dust became visible 30 to 50 meters above the surface, and during the final 10 to 20 meters of descent, the surface was largely obscured by the dust cloud. On other missions, the dust cloud was not as dense and the surface remained clearly visible throughout the landing.

The soil on the Moon is very fine-grained, with more than half of all grains being dust particles less than 0.1 millimeters across. Some of these particles become electrostatically charged and cling to objects (such as space suits and other equipment) that they come in contact with. The dark dust grains absorb sunlight, and equipment that became dust-coated sometimes became excessively hot. Despite the fine-grained nature of the surface, it provided good traction for astronauts as they moved about. Crew mobility, both on foot and in the lunar rover, was affected more by local topography such as craters and ridges than by soil properties.

The lunar surface easily supported the weight of the astronauts and their equipment. Typically, astronaut boots and the lunar rover's wheels only penetrated 1 to 2 centimeters into the surface, with penetration reaching five centimeters in some places. The lunar module footpads sank 2 to 20 centimeters into the soil. When astronauts inserted sampling tubes into the soil, they typically found penetration was easy for the first 10 to 20 centimeters and increasingly difficult below that depth. The deepest penetration achieved on a hand-driven core tube was 70 centimeters, which required about 50 blows with a hammer. For sampling at greater depths, the Apollo 15, 16, and 17 crews used a battery-powered drill. This allowed sampling to depths of 1.5 to 3 meters, which was achieved easily on Apollo 16 but with much more difficulty on Apollo 15 and 17.

Source: Apollo 17 Soil Mechanics Investigation

This high-resolution 3-D view of the lunar soil is one of several obtained using a close-up stereoscopic camera placed at different locations by the Apollo 14 astronauts during their moonwalks. A “raindrop” pattern can be seen in this close-up image of undisturbed lunar soil. The raindrop patterns noticed by the astronauts are small pits formed by the continual impact of micrometeorites (smaller than 1 millimeter) into the lunar soil. Rock samples brought back from the Moon have impact pits as small as a few millimeters across. Apollo 14 landed in the Fra Mauro highlands in February 1971.

Source: slide 22

How did orange soil appear on the Moon? This mystery began when astronaut Harrison Schmidt noticed the off-color patch near Apollo 17's Taurus-Littrow landing site in 1972. Schmidt and fellow astronaut Eugene Cernan scooped up some of the unusual orange soil for detailed inspection back on Earth. Pictured above is a return sample shown greatly magnified, with its discovery location shown in the inset. The orange soil contains particles less than 0.1 millimeter across, some of the smallest particles yet found on the Moon. Lunar geologists now think that the orange soil was created during an ancient fire-fountain. Detailed chemical and dating analyses indicate that during an explosive volcanic eruption 3.64 billion years ago, small drops of molten rock cooled rapidly into the nearly spherical colored grains. The origin of some of the unusual elements found in the soil, however, remains unknown.

Source: Orange moon soil (Experts examining orange soil from moon found by Apollo XVII astronauts say soil 3 1/2 billion years old.)

The soil on the moon stores earth’s early breath The moon’s soil preserves gases from the ancient Earth’s atmosphere, say scientists who have studied results from Apollo missions. Lunar soil samples hint that our planet’s magnetic field switched on about 3.9 billion years ago. This, in turn, points to when life began on Earth, as the magnetic field protects us from a hail of DNA-damaging particles from space.

Although Earth formed some 4.5 billion years ago, current theories suggest that its magnetic field only kicked in after its core cooled. But no one knows exactly when this was, and researchers have been short on evidence.

Minoru Ozima, a geochemist at the University of Tokyo, Japan, and his colleagues came up with a new approach to the question after looking at the data from soil samples brought back by astronauts in the 1970s.

Moon soils contain traces of volatile elements such as nitrogen and argon. Scientists have long assumed that blasts of solar wind, flowing from the sun’s upper atmosphere, drilled these atoms into the soil.

Source: The soil on the moon stores earth’s early breath Whatever ice there is in these crater floors is likely in frozen patches, spread out in low concentrations. If there are any ice sheets at all on the Moon, they would be less than an inch thick and inter-layered within the lunar soil. Added up though, the Moon still could have a lot of ice.

The likely scenario is that the ice is thoroughly mixed in with the soil in these crater floors. It gets mixed in so well because the Moon's soil is constantly being "gardened" or turned over. Since the Moon has no atmosphere to speak of, meteors don't burn up on entry as they do on Earth. Instead, all the meteors strike the Moon's surface, churning up the soil mixing it with the ice.

With ice mixed intermixed with lunar soil, it will be more difficult to extract. Even so, it will most likely be more practical to collect lunar ice than to transport water from Earth.

Source: Lunar ice

Mars
Banin's comments were about Mars but predicated on an absence of life. The following indicates that life was present on Mars. So that means what in terms of support, opposition, neutral to Banin?

Sulfates on Mars suggests life existed. Organic materials, including amino acids and their degradation products, were detected in ancient sulfate minerals such as jarosite (photo) and gypsum. This finding is reported by Andrew Aubrey and associates at University of California at San Diego and Berkeley; Jet Propulsion Laboratory, California; and Leiden Observatory, Netherlands. They also report that amino acids and amines appear to be preserved for geologically long periods of time in sulfate minerals. These minerals should be prime targets for organic compounds including those of biological origin. Jarosite is a hydrated iron sulfate mineral, uncommon on Earth (Spain), and it is cited as evidence that water existed. Gypsum, known as plaster of Paris, is a hydrated calcium sulfate and is also indicative of water. (Geology 34(5): 357-360, 2006)

Source: Sulfates on Mars suggest life existed

Sulfate minerals and organic compounds on Mars

Andrew Aubrey, Scripps Institution of Oceanography, Geosciences Research Division, La Jolla, CA 92093-0212, USA; and Jeffrey L. Bada (corresponding author), University of California–San Diego, Scripps Institution of Oceanography, La Jolla, CA 92093-0212, USA; et al. Pages 357-360.

The search for evidence of life on Mars involves the detection of organic molecules considered to be associated with either extinct or extant life. The recent finding of abundant sulfate minerals on Mars suggests that these minerals might be prime targets in the search for organic compounds. Aubrey et al. have determined the total organic carbon (C) and nitrogen (N) content, the stable C and N isotopic composition, and the amine and amino acid concentrations in 5 terrestrial sulfate minerals with ages up to 30 million years old. The interpretation of the results fits a model of amino acid degradation, and this model is used to estimate the degradation half-lives of amino acids in sulfate minerals on Mars. The Aubrey et al. model indicates that the degradation of amino acids in sulfate minerals is slow enough to be preserved in the sulfate mineral rock record on Mars for periods of at least 1 billion years. Thus, sulfate minerals provide excellent targets in the search for biomolecules derived from extinct or extant life on Mars.

Source: Sulfate minerals and organic compounds on Mars