A lunar regolith simulant is a terrestrial material synthesized in order to approximate the chemical, mechanical, or engineering properties of, and the mineralogy and particle size distributions of, lunar

regolith Regolith () is a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock. It includes dust, broken rocks, and other related materials and is present on Earth, the Moon, Mars, some asteroids, and other terrestr ...

. Lunar regolith simulants are used by researchers who wish to research the materials handling, excavation, transportation, and uses of lunar regolith. Samples of actual lunar regolith are too scarce, and too small, for such research, and in any case have been contaminated by exposure to Earth's atmosphere.

Early simulants

In the run-up to the Apollo program, crushed terrestrial rocks were first used to simulate the anticipated soils that astronauts would encounter on the lunar surface. In some cases the properties of these early simulants were substantially different from actual lunar soil, and the issues associated with the pervasive, fine-grained, sharp dust grains on the Moon came as a surprise.

Later simulants

After Apollo and particularly during the development of the

Constellation program The Constellation program (abbreviated CxP) was a crewed spaceflight program developed by NASA, the space agency of the United States, from 2005 to 2009. The major goals of the program were "completion of the International Space Station" and a ...

, there was a large proliferation of lunar simulants produced by different organizations and researchers. Many of these were given three-letter acronyms to distinguish them (e.g., MLS-1, JSC-1), and numbers to designate subsequent versions. These simulants were broadly divided into highlands or mare soils, and were usually produced by crushing and sieving analogous terrestrial rocks (anorthosite for highlands, basalt for mare). Returned Apollo and Luna samples were used as reference materials in order to target specific properties such as elemental chemistry or particle size distribution. Many of these simulants were criticized by prominent lunar scientist Larry Taylor for a lack of quality control and wasted money on features like nanophase iron that had no documented purpose.

JSC-1 and -1A

JSC-1 (Johnson Space Center Number One) was a lunar regolith simulant that was developed in 1994 by

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

and the

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 ...

. Its developers intended it to approximate the

lunar soil Lunar soil is the fine fraction of the regolith found on the surface of the Moon. Its properties can differ significantly from those of terrestrial soil. The physical properties of lunar soil are primarily the result of mechanical disinteg ...

of the maria. It was sourced from a

basalt Basalt (; ) is an 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 surface of a rocky planet or moon. More than 90 ...

ic ash with a high glass content. In 2005, NASA contracted with Orbital Technologies Corporation (ORBITEC) for a second batch of simulant in three grades: * JSC-1AF, fine, 27 µm average size * JSC-1A, a reproduction of JSC 1, less than 1 mm size * JSC-1AC, coarse, a distribution of sizes < 5 mm NASA received 14 metric tons of JSC-1A, and one ton each of AF and AC in 2006. Another 15 tons of JSC-1A and 100 kg of JSC-1F were produced by ORBITEC for commercial sale, but ORBITEC is no longer selling simulants and was acquired by the Sierra Nevada Corporation. An 8-ton sand box of commercial JSC‐1A is available for daily rental from the NASA Solar System Exploration Research Virtual Institute (SSERVI). JSC-1A can

geopolymer Geopolymers are inorganic, typically ceramic, alumino-silicate forming long-range, covalently bonded, non-crystalline (amorphous) networks. Obsidian (volcanic glass) fragments are a component of some geopolymer blends. Commercially produced geopo ...

ize in an alkaline solutions resulting in a hard, rock-like, 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 elonga ...

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 frequ ...

of the 'lunar' geopolymer is comparable to that of conventional cements. Lunar Martial Geopolymers

JSC-1 and JSC-1A are now no longer available outside of NASA centers.

NU-LHT and OB-1

Two lunar highlands simulants, the NU-LHT (lunar highlands type) series and OB-1 (olivine-bytownite) were developed and produced in anticipation of the Constellation activities. Both of these simulants are sourced mostly from rare

anorthosite Anorthosite () is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most ...

deposits on the Earth. For NU-LHT the anorthosite came from the Stillwater complex, and for OB-1 it came from the Shawmere Anorthosite in Ontario. Neither of these simulants were widely distributed.

Recent simulants

Most of the previously developed lunar simulants are no longer being produced or distributed outside of NASA. Multiple companies have tried to sell regolith simulants for profit, including Zybek Advanced Products, ORBITEC, and

Deep Space Industries Deep Space Industries, or DSI, was an American private ly-held company operating in the space technology and space exploration sectors. It was acquired on January 1, 2019 by Bradford Space. The company is developing and building spacecraft tech ...

. None of these efforts have seen much success. NASA is unable to sell simulants, or distribute unlimited amounts for free; however, NASA can award set amounts of simulant to grant winners. Several lunar simulants have been developed recently and are either being sold commercially or are available for rent inside large regolith bins. These include the ''OPRL2N Standard Representative Lunar Mare Simulant'' and ''Standard Representative Lunar Highland Simulant''. Off Planet Research also produces customized simulants for specific locations on the Moon including lunar polar icy regolith simulants that include the volatiles identified in the

LCROSS The Lunar Crater Observation and Sensing Satellite (LCROSS) was a robotic spacecraft operated by NASA. The mission was conceived as a low-cost means of determining the nature of hydrogen detected at the polar regions of the Moon. Launched immed ...

mission. Other simulants include ''Lunar Highlands Simulant (LHS-1)'' and ''Lunar Mare Simulant (LMS-1)'' produced and distributed by the not-for-profit Exolith Lab run out of 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 Universi ...

.Exolith Lab
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Early simulants

Later simulants

JSC-1 and -1A

NU-LHT and OB-1

Recent simulants

See also

References

Further reading