Martian regolith simulant (or Martian soil simulant) is a terrestrial material that is used to simulate the chemical and mechanical properties of Martian regolith for research, experiments and

prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...

testing of activities related to Martian regolith such as dust mitigation of transportation equipment, advanced

life support system A life-support system is the combination of equipment that allows survival in an environment or situation that would not support that life in its absence. It is generally applied to systems supporting human life in situations where the outsid ...

s and

in-situ resource utilization In space exploration, in situ resource utilization (ISRU) is the practice of collection, processing, storing and use of materials found or manufactured on other astronomical objects (the Moon, Mars, asteroids, etc.) that replace materials that ...

Variations

JSC Mars-1 and JSC Mars-1A

After the Viking landers and the Mars Pathfinder's rover landed on Mars, the onboard instruments were used to determine the properties of the

Martian soil Martian soil is the fine regolith (a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock) found on the surface of Mars. Its properties can differ significantly from those of terrestrial soil, including its to ...

at the landing sites. The studies of the

properties led to the development of JSC Mars-1 Martian regolith simulant at NASA's

Johnson Space Center The Lyndon B. Johnson Space Center (JSC) is NASA's center for human spaceflight (originally named the Manned Spacecraft Center), where human spaceflight training, research, and flight control are conducted. It was renamed in honor of the late U ...

in 1998. It contained palagonitic

tephra Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they rem ...

with a

particle size Particle size is a notion introduced for comparing dimensions of solid particles ('' flecks''), liquid particles ('' droplets''), or gaseous particles ('' bubbles''). The notion of particle size applies to particles in colloids, in ecology, in ...

fraction of less than 1 millimeter. The palagonitic tephra, which is glassy

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcano, volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used t ...

altered at low temperature, was mined from a quarry at the Pu'u Nene

cinder cone A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions o ...

. The studies of the cone, which is located between

Mauna Loa Mauna Loa ( or ; Hawaiian: ; en, Long Mountain) is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaii in the Pacific Ocean. The largest subaerial volcano (as opposed to subaqueous volcanoes) in both mass and ...

and

Mauna Kea Mauna Kea ( or ; ; abbreviation for ''Mauna a Wākea''); is a dormant volcano on the island of Hawaii. Its peak is above sea level, making it the highest point in the state of Hawaii and second-highest peak of an island on Earth. The peak is ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

, indicate that the tephra is a close spectral analog to the bright regions of Mars. When the original supply of JSC Mars-1 ran out, there were needs for additional material. NASA's

Marshall Space Flight Center The George C. Marshall Space Flight Center (MSFC), located in Redstone Arsenal, Alabama (Huntsville postal address), is the U.S. government's civilian rocketry and spacecraft propulsion research center. As the largest NASA center, MSFC's first ...

contracted Orbital Technologies Corporation to supply 16

metric tons The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United States ...

of lunar and Martian simulants. The company also made an additional eight tons of Martian simulant available for other interested parties to purchase. However, as of 2017 JSC Mars-1A is no longer available. After milling to reduce its particle size, JSC Mars-1A can geopolymerize in alkaline solutions forming a solid material. Tests show that the maximum

compressive In continuum mechanics, stress is a physical quantity. It is a quantity that describes the magnitude of forces that cause deformation. Stress is defined as ''force per unit area''. When an object is pulled apart by a force it will cause elon ...

and

flexural strength Flexural strength, also known as modulus of rupture, or bend strength, or transverse rupture strength is a material property, defined as the stress in a material just before it yields in a flexure test. The transverse bending test is most freque ...

of the 'martian' geopolymer is comparable to that of common clay bricks. Lunar Martial Geopolymers

MMS

MMS or Mojave Mars Simulant was developed in 2007 to address some issues with JSC Mars-1. While JSC Mars-1 did simulate the color of Martian regolith, it performed poorly in many qualities, including its

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

tendencies—it had undergone

weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...

that attracts water, making it more

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

-like. MMS, however, was hygroscopically inert due to minimal weathering and the way it was crushed, which allowed it to better simulate that feature of Martian regolith, among others. MMS was found naturally as whole rocks in a volcanic formation near the town of

Boron, California Boron (formerly Amargo, Baker, Borate, and Kern) is a census-designated place (CDP) in Kern County, California, United States. Boron is southwest of Red Rock Mountain at an elevation of . The population was 2,086 at the 2020 census, up from 2,025 ...

, in the western

Mojave desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily in ...

. After crushing,

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

sands were processed and graded into particular sizes, MMS Coarse and MMS Fine. MMS Dust consists of smaller basalt particles matching the particle size distribution of

Martian dust Martian soil is the fine regolith (a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock) found on the surface of Mars. Its properties can differ significantly from those of terrestrial soil, including its to ...

. A separate volcanic event created red-colored

cinder Cinder is an alternate term for scoria. Cinder or Cinders may also refer to: In computing *Cinder (programming library), a C++ programming library for visualization *Cinder, OpenStack's block storage component * Cyber Insider Threat, CINDER, a ...

which is mined and crushed to create MMS Cinder.

MGS-1

MGS-1 or Mars Global Simulant was developed starting in 2018 as the first mineralogically accurate Martian regolith simulant. It is based on the Rocknest soil in

Gale crater Gale is a crater, and probable dry lake, at in the northwestern part of the Aeolis quadrangle on Mars. It is in diameter and estimated to be about 3.5–3.8 billion years old. The crater was named after Walter Frederick Gale, an amateur ast ...

on Mars that has been analyzed extensively by the NASA Curiosity rover. MGS-1 is produced by mixing pure minerals together in accurate proportions, with a realistic particle size distribution. The simulant is available from the not-for-profit Exolith Lab at the

University of Central Florida The University of Central Florida (UCF) is a public research university whose main campus is in unincorporated Orange County, Florida. UCF also has nine smaller regional campuses throughout central Florida. It is part of the State University ...

. MGS-1 does not include perchlorates by default, so cannot be used to test the effects of that aspect of the Martian regolith. However, end users can spike the material with perchlorate salts or other superoxide species.

Health risks

Exposure to regolith simulants may pose some health risks due to the fine particles and the presence of crystalline silica. JSC Mars-1A has slight hazard on inhalation and eye contact which may cause irritation to eyes and

respiratory tract The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa. Air is breathed in through the nose to th ...

. There has been research into the toxicity of the simulants to the body cells. JSC MARS-1 is considered to have dose-dependent

cytotoxicity Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cells ...

. Therefore, it is recommended for precautions to minimize fine dust exposure in large-scale engineering applications. Although perchlorates were discovered on Mars in 2008 by the

Phoenix lander ''Phoenix'' was an uncrewed space probe that landed on the surface of Mars on May 25, 2008, and operated until November 2, 2008. ''Phoenix'' was operational on Mars for Timekeeping on Mars#Sols, sols ( days). Its instruments were used to asse ...

, none of the simulants include

perchlorate A perchlorate is a chemical compound containing the perchlorate ion, . The majority of perchlorates are commercially produced salts. They are mainly used as oxidizers for pyrotechnic devices and to control static electricity in food packaging. Per ...

s. This reduces the health risk posed by the simulants compared to actual

. Early simulants predated this discovery, but the latest simulant, MGS-1, still does not include them.

Structural use

A study at

UCSD The University of California, San Diego (UC San Diego or colloquially, UCSD) is a public university, public Land-grant university, land-grant research university in San Diego, California. Established in 1960 near the pre-existing Scripps Insti ...

showed that Martian regolith could be formed by itself into very strong bricks, with application of pressure.

References

{{reflist, 25em Materials science Surface features of Mars