spore: profile
id: nu-lht-2m
spore_version: 0.2
family: regolith
name: NU-LHT-2M lunar highlands simulant
abbreviation: NU-LHT-2M
role: Ground test stand-in for lunar highlands regolith (Apollo 16 type)
category: regolith
type: lunar-simulants
summary: |
  NU-LHT-2M is a lunar highlands regolith simulant made by NASA and the USGS from Stillwater anorthosite and norite, with synthetic pseudo-agglutinate and good glass. It was designed to match the average composition, particle size and particle shape of Apollo 16 sample 64001/64002. NASA's 2024 user guide lists it as the prototype version of the NU-LHT series and says only very small amounts remain for NASA testing.
best_for: Ground tests of excavation, drilling and abrasion, and oxygen-extraction feedstock for highlands composition (2010 NASA guide)
weakest_at: Cohesion and friction angle are not reported for NU-LHT-2M (n/a in the 2024 guide), and supply is nearly exhausted
identity:
  formula: Highlands simulant made of crystalline Stillwater anorthosite and norite (65%), pseudo-agglutinate (30%) and good glass (5%) by design, with minor synthetic whitlockite, fluorapatite and pyrite (troilite substitute)
  source: nasa-tm-2024-guide
  where: Section 3, page 20 (mixing ratio and minor minerals); page 19 (feedstock)
tags:
  environments: []
  stresses:
    - dust-abrasion
  applications:
    - rovers-and-surface-systems
    - habitats-and-suits
    - propulsion-and-tanks
properties:
  - benchmark: density
    label: Bulk density range, NU-LHT-2M (minimum to maximum)
    value: 1.37
    value_high: 2.06
    bound: range
    unit: g/cm3
    scope: material
    conditions:
      material: NU-LHT-2M lunar highlands simulant
      basis: rho(min) and rho(max) as printed; the table does not state compaction or moisture
    method: Averaged rho(min) and rho(max) values printed in the table, citing Zeng et al. 2010
    status: ground
    source: nasa-tm-2024-guide
    where: Table 16, Lunar Simulant Density Values, NU-LHT-2M row
  - benchmark: density
    label: Bulk density range, Apollo 16 regolith (first of two rows in the table)
    value: 1.4
    value_high: 1.8
    bound: range
    unit: g/cm3
    scope: material
    conditions:
      material: Apollo 16 lunar regolith (reference, not a simulant)
      basis: rho(min) and rho(max) as printed
    method: Printed range for Apollo 16, cited to Mitchell et al. 1972b and Carrier 1974
    status: ground
    source: nasa-tm-2024-guide
    where: Table 15, Lunar Regolith Density values, Apollo 16 first row
  - benchmark: density
    label: Bulk density range, Apollo 16 regolith (second row in the table, disagrees with the first)
    value: 1.47
    value_high: 1.75
    bound: range
    unit: g/cm3
    scope: material
    conditions:
      material: Apollo 16 lunar regolith (reference, not a simulant)
      basis: rho(min) and rho(max) as printed
    method: Printed range for Apollo 16, cited to Carrier 1974
    status: ground
    note: The two Apollo 16 rows in the table give different ranges; both are kept.
    source: nasa-tm-2024-guide
    where: Table 15, Lunar Regolith Density values, Apollo 16 second row
  - benchmark: particle_size_q25
    label: Particle size, 25th percentile (Q25), NU-LHT-2M
    value: 55.9
    unit: µm
    scope: material
    conditions:
      quartile: Q25
      basis: average QN of the simulant PSD as printed
      material: NU-LHT-2M
    method: Average Q25 printed in the table; the text below the table credits Clark 2021 (JSC-ARES) with laser diffraction (ISO 13320-1)
    status: ground
    source: nasa-tm-2024-guide
    where: Table 10, NU-LHT-2M row, Q25 column; method text below Table 10
  - benchmark: particle_size_q50
    label: Particle size, median (Q50), NU-LHT-2M
    value: 125.7
    unit: µm
    scope: material
    conditions:
      quartile: Q50
      basis: average QN of the simulant PSD as printed
      material: NU-LHT-2M
    method: Average Q50 printed in the table; the text below the table credits Clark 2021 (JSC-ARES) with laser diffraction (ISO 13320-1)
    status: ground
    source: nasa-tm-2024-guide
    where: Table 10, NU-LHT-2M row, Q50 column; method text below Table 10
  - benchmark: particle_size_q75
    label: Particle size, 75th percentile (Q75), NU-LHT-2M
    value: 244.5
    unit: µm
    scope: material
    conditions:
      quartile: Q75
      basis: average QN of the simulant PSD as printed
      material: NU-LHT-2M
    method: Average Q75 printed in the table; the text below the table credits Clark 2021 (JSC-ARES) with laser diffraction (ISO 13320-1)
    status: ground
    source: nasa-tm-2024-guide
    where: Table 10, NU-LHT-2M row, Q75 column; method text below Table 10
  - benchmark: aspect_ratio
    label: Aspect ratio of bulk particle geometry, NU-LHT-2M
    value: 0.63
    unit: '-'
    scope: material
    conditions:
      material: NU-LHT-2M
      basis: bulk particle geometry value as printed (dimensionless)
    method: Value printed in the table, citing SDL 2022 (JSC-ARES)
    status: ground
    source: nasa-tm-2024-guide
    where: Table 13, Lunar regolith simulant particle geometry, NU-LHT-2M row, AR column
  - benchmark: root_form_factor
    label: Root form factor (square root of FF), NU-LHT-2M
    value: 0.91
    unit: '-'
    scope: material
    conditions:
      material: NU-LHT-2M
      basis: bulk particle geometry value as printed (dimensionless)
    method: Value printed in the table, citing SDL 2022 (JSC-ARES)
    status: ground
    source: nasa-tm-2024-guide
    where: Table 13, Lunar regolith simulant particle geometry, NU-LHT-2M row, root form factor column
  - benchmark: crystalline_silica_total
    label: Total crystalline silica, NU-LHT-2M (DCM Science Laboratories, 2023)
    value: 0.67
    unit: wt%
    scope: material
    conditions:
      basis: 'total crystalline silica as defined in the table footnote: quartz plus cristobalite plus tridymite'
      analysis_lab: DCM Science Laboratories (footnote symbol section mark)
    method: Analysis printed in Table 25; footnote defines the total
    status: ground
    source: nasa-tm-2024-guide
    where: Table 25, Summary of Total Percent Crystalline and Respirable Silica, NU-LHT-2M row, first entry
  - benchmark: crystalline_silica_total
    label: Total crystalline silica, NU-LHT-2M (Herndon Solutions Group, 2021)
    value: 0.82
    unit: wt%
    scope: material
    conditions:
      basis: total crystalline silica as defined in the table footnote
      analysis_lab: Herndon Solutions Group (footnote double dagger)
    method: Analysis printed in Table 25; no respirable value given for this analysis
    status: ground
    note: Disagrees with the 0.67 wt% DCM value above; both are kept.
    source: nasa-tm-2024-guide
    where: Table 25, NU-LHT-2M row, second entry
  - benchmark: crystalline_silica_respirable
    label: Respirable crystalline silica, NU-LHT-2M (DCM Science Laboratories, 2023)
    value: 0.07
    unit: wt%
    scope: material
    conditions:
      basis: crystalline silica in the respirable fraction (below 10 µm), removed by wet sieving through a 10 µm sieve
      analysis_lab: DCM Science Laboratories
    method: Analysis printed in Table 25
    status: ground
    source: nasa-tm-2024-guide
    where: Table 25, NU-LHT-2M row, Total Respirable Crystalline Silica column
  - benchmark: fraction_below_10um
    label: Percent passing below 10 µm (respirable fraction), NU-LHT-2M
    value: 10.1
    unit: wt%
    scope: material
    conditions:
      basis: percent passing the 10 µm sieve, DCM analysis only
      analysis_lab: DCM Science Laboratories
    method: Value printed in Table 25
    status: ground
    source: nasa-tm-2024-guide
    where: Table 25, NU-LHT-2M row, Percent Passing (below 10 µm) column
  - benchmark: bulk_sio2
    label: Bulk SiO2, NU-LHT-2M
    value: 47
    unit: wt%
    scope: material
    conditions:
      basis: bulk oxide chemistry as printed, wt.%
      material: NU-LHT-2M
    method: Oxide analysis printed in the table, cited to Wilson USGS 2020
    status: ground
    source: nasa-tm-2024-guide
    where: Table 7, Lunar Simulant Bulk Chemistry, NU-LHT-2M row, SiO2 column
  - benchmark: bulk_tio2
    label: Bulk TiO2, NU-LHT-2M
    value: 0.4
    unit: wt%
    scope: material
    conditions:
      basis: bulk oxide chemistry as printed, wt.%
      material: NU-LHT-2M
    method: Oxide analysis printed in the table, cited to Wilson USGS 2020
    status: ground
    source: nasa-tm-2024-guide
    where: Table 7, Lunar Simulant Bulk Chemistry, NU-LHT-2M row, TiO2 column
  - benchmark: bulk_al2o3
    label: Bulk Al2O3, NU-LHT-2M
    value: 24.5
    unit: wt%
    scope: material
    conditions:
      basis: bulk oxide chemistry as printed, wt.%
      material: NU-LHT-2M
    method: Oxide analysis printed in the table, cited to Wilson USGS 2020
    status: ground
    source: nasa-tm-2024-guide
    where: Table 7, Lunar Simulant Bulk Chemistry, NU-LHT-2M row, Al2O3 column
  - benchmark: bulk_feo
    label: Bulk FeO, NU-LHT-2M
    value: 3.7
    unit: wt%
    scope: material
    conditions:
      basis: bulk oxide chemistry as printed, wt.%
      material: NU-LHT-2M
    method: Oxide analysis printed in the table, cited to Wilson USGS 2020
    status: ground
    note: The 2010 guide describes NU-LHT-2M as slightly low in FeO against a lunar reference of about 5 wt.% (Table 8 text); the 2024 Apollo highlands average is 6.6 wt.% (Table 6). Both references are recorded in the story.
    source: nasa-tm-2024-guide
    where: Table 7, Lunar Simulant Bulk Chemistry, NU-LHT-2M row, FeO column
  - benchmark: bulk_mgo
    label: Bulk MgO, NU-LHT-2M
    value: 8.4
    unit: wt%
    scope: material
    conditions:
      basis: bulk oxide chemistry as printed, wt.%
      material: NU-LHT-2M
    method: Oxide analysis printed in the table, cited to Wilson USGS 2020
    status: ground
    source: nasa-tm-2024-guide
    where: Table 7, Lunar Simulant Bulk Chemistry, NU-LHT-2M row, MgO column
  - benchmark: bulk_cao
    label: Bulk CaO, NU-LHT-2M
    value: 13.6
    unit: wt%
    scope: material
    conditions:
      basis: bulk oxide chemistry as printed, wt.%
      material: NU-LHT-2M
    method: Oxide analysis printed in the table, cited to Wilson USGS 2020
    status: ground
    source: nasa-tm-2024-guide
    where: Table 7, Lunar Simulant Bulk Chemistry, NU-LHT-2M row, CaO column
  - benchmark: bulk_na2o
    label: Bulk Na2O, NU-LHT-2M
    value: 1.5
    unit: wt%
    scope: material
    conditions:
      basis: bulk oxide chemistry as printed, wt.%
      material: NU-LHT-2M
    method: Oxide analysis printed in the table, cited to Wilson USGS 2020
    status: ground
    source: nasa-tm-2024-guide
    where: Table 7, Lunar Simulant Bulk Chemistry, NU-LHT-2M row, Na2O column
  - benchmark: bulk_k2o
    label: Bulk K2O, NU-LHT-2M
    value: 0.1
    unit: wt%
    scope: material
    conditions:
      basis: bulk oxide chemistry as printed, wt.%
      material: NU-LHT-2M
    method: Oxide analysis printed in the table, cited to Wilson USGS 2020
    status: ground
    source: nasa-tm-2024-guide
    where: Table 7, Lunar Simulant Bulk Chemistry, NU-LHT-2M row, K2O column
  - benchmark: plagioclase_modal
    label: Plagioclase, particle-type modal share, NU-LHT-2M
    value: 54.9
    unit: modal %
    scope: material
    conditions:
      basis: particle-type modal data from electron beam (QEMSCAN) analysis; the table prints no unit and the figure axis reads Modal (%)
      material: NU-LHT-2M
    method: Value printed in Table 2 (particle type modal data)
    status: ground
    source: nasa-tm-2010-216446
    where: Table 2, particle type modal data, NU-LHT-2M column, Plagioclase row
  - benchmark: glass_modal
    label: Glass, particle-type modal share, NU-LHT-2M
    value: 7.2
    unit: modal %
    scope: material
    conditions:
      basis: particle-type modal data from electron beam (QEMSCAN) analysis; the table prints no unit and the figure axis reads Modal (%)
      material: NU-LHT-2M
    method: Value printed in Table 2 (particle type modal data)
    status: ground
    source: nasa-tm-2010-216446
    where: Table 2, particle type modal data, NU-LHT-2M column, Glass row
  - benchmark: agglutinate_modal
    label: Agglutinates, particle-type modal share, NU-LHT-2M (2010 guide)
    value: 23.5
    unit: modal %
    scope: material
    conditions:
      basis: particle-type modal data from electron beam (QEMSCAN) analysis; the table prints no unit and the figure axis reads Modal (%)
      material: NU-LHT-2M
    method: Value printed in Table 2 (particle type modal data)
    status: ground
    note: The 2024 guide gives 29.02 wt.% agglutinate for the same simulant (below); the two values differ and are not reconciled in either source.
    source: nasa-tm-2010-216446
    where: Table 2, particle type modal data, NU-LHT-2M column, Agglutinates row
  - benchmark: agglutinate_wt
    label: Agglutinates, NU-LHT-2M (2024 guide, wt.%)
    value: 29.02
    unit: wt%
    scope: material
    conditions:
      basis: modal mineralogy by mineral group as printed, wt.%
      material: NU-LHT-2M
    method: Value printed in Table 5, modal mineralogy by FoM mineral group
    status: ground
    note: The 2010 guide gives 23.5 modal % for the same simulant; the two values differ and are both kept.
    source: nasa-tm-2024-guide
    where: Table 5, Lunar regolith simulant modal mineralogy (wt.%), NU-LHT-2M row, Agglutinates column
  - benchmark: olivine_modal
    label: Olivine, particle-type modal share, NU-LHT-2M
    value: 9.5
    unit: modal %
    scope: material
    conditions:
      basis: particle-type modal data from electron beam (QEMSCAN) analysis; the table prints no unit and the figure axis reads Modal (%)
      material: NU-LHT-2M
    method: Value printed in Table 2 (particle type modal data)
    status: ground
    source: nasa-tm-2010-216446
    where: Table 2, particle type modal data, NU-LHT-2M column, Olivine row
  - benchmark: clinopyroxene_modal
    label: Clinopyroxene, particle-type modal share, NU-LHT-2M
    value: 4
    unit: modal %
    scope: material
    conditions:
      basis: particle-type modal data from electron beam (QEMSCAN) analysis; the table prints no unit and the figure axis reads Modal (%)
      material: NU-LHT-2M
    method: Value printed in Table 2 (particle type modal data)
    status: ground
    source: nasa-tm-2010-216446
    where: Table 2, particle type modal data, NU-LHT-2M column, Clinopyroxene row
  - benchmark: plagioclase_anorthite
    label: Plagioclase anorthite content, NU-LHT-2M
    value: 80
    unit: An%
    scope: material
    conditions:
      basis: molar percent anorthite end-member of plagioclase, as printed in the row labelled Plag. An%
      material: NU-LHT-2M
      reference: Apollo 64001/64002 reference is 95 An% in the same table
    method: Value printed in Table 2, Plag. An% row
    status: ground
    source: nasa-tm-2010-216446
    where: Table 2, (Plag. An%) row, NU-LHT-2M column
  - benchmark: particle_shape_rounded
    label: Rounded particles, QEMSCAN shape class share, NU-LHT-2M
    value: 52.8
    unit: wt%
    scope: material
    conditions:
      basis: QEMSCAN shape classes by weight percent of geologic classification bins
      material: NU-LHT-2M
    method: Value printed in Table 6, shape parameters derived by QEMSCAN
    status: ground
    source: nasa-tm-2010-216446
    where: Table 6, Shape parameters of simulants, NU-LHT-2M column, Rounded row
  - benchmark: fom_composition_score
    label: Figure of Merit, composition, NU-LHT-2M against lunar reference 64001/64002
    value: 0.55
    unit: '-'
    scope: material
    conditions:
      basis: FoM Revision 1 composition algorithm against reference 64001/64002, score as printed
    method: Score printed in Table 3, FoM composition analysis
    status: ground
    source: nasa-tm-2010-216446
    where: Table 3, Results of FoM composition analysis, NU-LHT-2M row
  - benchmark: specific_gravity
    label: Specific gravity, NU-LHT-2M (NASA JSC ARES geomechanical table)
    value: 2.749
    unit: g/cm3
    scope: material
    conditions:
      material: NU-LHT-2M
      basis: specific gravity as printed in the ARES table, with its reference [2] (Zeng et al. 2010)
    method: Value printed in the ARES Geomechanical Properties table for NU-LHT-2M, citing Zeng et al. (2010), Journal of Aerospace Engineering 23(4), 213-218
    status: ground
    source: nasa-ares-nu-lht
    where: Geomechanical Properties for NU-LHT-2M table, Specific Gravity column
  - benchmark: density
    label: Bulk density range, NU-LHT-2M (NASA JSC ARES geomechanical table)
    value: 1.648
    value_high: 1.869
    bound: range
    unit: g/cm3
    scope: material
    conditions:
      material: NU-LHT-2M
      basis: bulk density range as printed in the ARES table, with its reference [2] (Zeng et al. 2010)
    method: Range printed in the ARES Geomechanical Properties table, citing Zeng et al. (2010)
    status: ground
    note: The 2024 guide Table 16 gives a different range for the same simulant (1.37 to 2.06 g/cm3, above); both are kept.
    source: nasa-ares-nu-lht
    where: Geomechanical Properties for NU-LHT-2M table, Density (g/cm 3) Bulk row
  - benchmark: void_ratio
    label: Void ratio range, NU-LHT-2M (NASA JSC ARES geomechanical table)
    value: 0.332
    value_high: 1.004
    bound: range
    unit: '-'
    scope: material
    conditions:
      material: NU-LHT-2M
      basis: dimensionless void ratio range as printed in the ARES table, with its reference [2]
    method: Range printed in the ARES Geomechanical Properties table, citing Zeng et al. (2010)
    status: ground
    source: nasa-ares-nu-lht
    where: Geomechanical Properties for NU-LHT-2M table, Void Ratio row
  - benchmark: friction_angle
    label: Triaxial friction angle, NU-LHT-2M (NASA JSC ARES geomechanical table)
    value: 36
    value_high: 40.7
    bound: range
    unit: °
    scope: material
    conditions:
      material: NU-LHT-2M
      basis: triaxial shear strength, friction angle as printed in the ARES table; the same table gives no cohesion value for this simulant
    method: Range printed in the ARES Geomechanical Properties table, citing Zeng et al. (2010)
    status: ground
    note: The 2024 guide Table 19 prints n/a for NU-LHT-2M cohesion and friction angle; the ARES page gives a value and the 2024 guide does not, so both are kept.
    source: nasa-ares-nu-lht
    where: Geomechanical Properties for NU-LHT-2M table, Triaxial Shear Strength, Friction Angle column
corrosion:
  - environment: Moist air during storage and transport
    headline: Simulant takes up water from moist air and can weather over time, so the 2024 guide says to store it away from moist air.
    effect: The 2024 guide says simulant materials must be stored to minimise or eliminate contact with moist air, to avoid water intake and possible weathering over time. It also says all simulants show some hygroscopicity and that available simulants are often contaminated with adsorbed water and humid air from transportation and previous testing. This is a general statement for simulants; no NU-LHT-2M-specific water-uptake value was found in the sections read.
    rating: moderate
    conditions:
      basis: general statement for lunar regolith simulants; the rating is the assistant's judgment, as the guide gives none
      exposure: storage and transport; no humidity level or time given
    source: nasa-tm-2024-guide
    where: Section 6.3 (storage paragraph); Section 6.3.1 (Desiccation); Section 6.2.1.B.(i) (Low Temperatures, adsorbed water)
  - environment: Size segregation during storage and transport (physical change)
    headline: Stored simulant segregates by size, so the particle size distribution changes unless the container is mixed before sampling.
    effect: The 2024 guide says the particle size distribution does not stay the same during transport and storage, because larger, more buoyant particles migrate upward when vibrated. It recommends homogenising stored simulant by rolling and overturning the containers before sampling, and measuring the size distribution of used simulant before reuse.
    rating: moderate
    conditions:
      basis: general statement for stored lunar regolith simulants; the rating is the assistant's judgment, as the guide gives none
      process: transport and storage in containers with vibration
    source: nasa-tm-2024-guide
    where: Section 6.3 (paragraph on size segregation)
  - environment: High-temperature processing in ambient air (oxidation)
    headline: Processing simulant at high temperature in ambient air can form oxidation products that would not form under lunar conditions.
    effect: The 2024 guide says high-temperature processing of regolith in ambient conditions increases the potential of forming oxidation products that would not be formed under lunar conditions. It says oxidation can involve minor components that change yields or form unwanted by-products, and it advises an inert atmosphere for ambient-pressure processing tests.
    rating: moderate
    conditions:
      basis: general statement for lunar regolith simulants; the guide gives no temperature for this statement; the rating is the assistant's judgment
      atmosphere: ambient air
    source: nasa-tm-2024-guide
    where: Section 6.2.1.B.(ii) (High Temperatures)
risks:
  hazards:
    - text: Crystalline silica is the main health concern for people using the simulant. The guide names quartz, cristobalite and tridymite, and says chronic inhalation of respirable particles below 10 microns can lead to pneumoconiosis, including silicosis.
      ghs: []
      source: nasa-tm-2024-guide
      where: Section 5.5.2 (Illness)
    - text: Table 25 gives NU-LHT-2M 0.67 wt.% total crystalline silica and 0.07 wt.% respirable crystalline silica (DCM 2023). The guide says crystalline silica is regulated under OSHA general industry and construction standards.
      ghs: []
      source: nasa-tm-2024-guide
      where: Table 25, NU-LHT-2M row; Section 5.5.2
    - text: PubChem's GHS record for cristobalite (ECHA notifications, EC 238-455-4), a crystalline silica phase the 2024 guide names, gives H350 'May cause cancer' (12.6% of notifications) and H372 'Causes damage to organs through prolonged or repeated exposure' (46%), with signal word Danger and pictogram GHS08. The percentages are the share of notifications that reported each code, as printed.
      ghs:
        - H350
        - H372
      source: pubchem-silica-ghs
      where: Safety and Hazards, GHS Classification (CID 24261), ECHA entry for Cristobalite (EC 238-455-4)
    - text: OSHA says respirable crystalline silica can cause silicosis, lung cancer, chronic obstructive pulmonary disease (COPD) and kidney disease, and that dust is created when stone, rock, concrete, brick and mortar are cut, sawed, ground, drilled or crushed.
      ghs: []
      source: osha-silica-page
      where: Crystalline silica topic page, health effects and dust-creation text
  failure_risks:
    - mode: Airborne particles and soil movement during vacuum pump-down
      trigger: Pumping down a simulant bed in a vacuum chamber, where adsorbed water comes off the particles
      consequence: The 2024 guide says simulant off-gasses violently during pump-down, that particulate matter poses a risk to chamber hardware (pumps and instruments), and that soil movement can make spouts of airborne particles that disturb the bed. Regulating the pump rate to keep pressure decay slow reduces the disturbance.
      severity: moderate
      source: nasa-tm-2024-guide
      where: Section 6.2.2.A.(i) (Dry Regolith Tests)
    - mode: Moisture carried into a test from storage or earlier use
      trigger: Simulant used without drying after transport or earlier testing
      consequence: Simulants are often contaminated with adsorbed water and humid air, which changes the starting state of a test. The guide recommends thorough drying before emplacement in the test environment; chamber evacuation removes some moisture, but ambient desiccation is limited.
      severity: moderate
      source: nasa-tm-2024-guide
      where: Section 6.2.1.B.(i) (Low Temperatures); Section 6.2.2.A.(i) (Dry Regolith Tests)
  side_effects:
    - text: The 2010 guide says the phosphates and sulfides in NU-LHT-2M are realistic but possibly hazardous to ISRU processes; the table does not say how.
      affects: ISRU oxygen-extraction processes that heat or reduce the feedstock
      source: nasa-tm-2010-216446
      where: Table 8, Oxygen Production column, NU-LHT-2M row
  handling:
    - text: The 2024 guide says eye protection, glasses or goggles, is needed depending on the simulant's physical characteristics.
      source: nasa-tm-2024-guide
      where: Section 5.5, text before 5.5.2
    - text: Crystalline silica can become airborne when workers chip, cut, drill or grind objects that contain silica.
      source: nasa-tm-2024-guide
      where: Section 5.5.2 (Illness)
    - text: OSHA's respirable crystalline silica standard sets the permissible exposure limit at no exposure 'in excess of 50 μg/m3, calculated as an 8-hour TWA' (29 CFR 1910.1053(c)), with an action level of 25 μg/m3 calculated as an 8-hour TWA (29 CFR 1910.1053(b)).
      source: osha-1910-1053
      where: 29 CFR 1910.1053, paragraphs (b) and (c)
  mitigations:
    - text: The 2024 guide says simulant used in ambient-condition mechanical testing should be stored dry in a location with active humidity control; if that is not possible, it should be desiccated first using the Section 6.3.1 methods.
      source: nasa-tm-2024-guide
      where: Section 6.2.1 key recommendations (ambient condition mechanical testing); Section 6.3.1 (Desiccation)
uses:
  - application: rovers-and-surface-systems
    device: Excavation and flow testing
    example: The 2010 guide rates NU-LHT-2M recommended for excavation and flow, because pseudo-agglutinates affect geomechanical behavior that may be important to excavation.
    source: nasa-tm-2010-216446
    where: Table 7, fit-to-use matrix, Excavation/Flow column, NU-LHT-2M row
  - application: rovers-and-surface-systems
    device: Drilling and abrasion or wear testing
    example: The 2010 guide rates NU-LHT-2M recommended for drilling and abrasion, because fidelity to mineral and glass percentages should yield appropriate abrasiveness.
    source: nasa-tm-2010-216446
    where: Table 7, fit-to-use matrix, Drilling and Abrasion/Wear columns, NU-LHT-2M row
  - application: propulsion-and-tanks
    device: Oxygen production feedstock for in-situ resource utilization tests
    example: The 2010 guide rates NU-LHT-2M most recommended for highlands oxygen production, with slightly low FeO against the lunar reference (about 4 against 5 wt.%); it also says the high iron in silicates will slow reduction.
    source: nasa-tm-2010-216446
    where: Table 8, Oxygen Production column, NU-LHT-2M row
  - application: habitats-and-suits
    device: Human health and dust studies
    example: The 2010 guide rates NU-LHT-2M the most suitable composition for human health studies, with a reasonable PSD that is too coarse in the fine fraction.
    source: nasa-tm-2010-216446
    where: Table 8, Human Health Studies column, NU-LHT-2M row
supply:
  - subject: NU-LHT-2M simulant (USGS and NASA)
    abundance: not stated in the three sources
    producers: []
    critical_lists: []
    recycling: not stated in the three sources
    substitutes: []
    source: nasa-tm-2024-guide
    where: Table 2 (producer USGS/NASA, footnote ** says these entities no longer manufacture the simulant); Section 3.4 (only very small amounts still exist for NASA testing); Section 3.5 (NU-LHT supply was about spent)
  - subject: Feldspar, the mineral class of the anorthosite feedstock (USGS feldspar chapter; not NU-LHT-2M itself)
    abundance: not stated in the USGS feldspar chapter
    producers:
      - country: India
        share_percent: 19.4
        year: 2025
      - country: Turkey
        share_percent: 17.1
        year: 2025
      - country: Iran
        share_percent: 12.6
        year: 2025
      - country: China
        share_percent: 11.9
        year: 2025
      - country: Italy
        share_percent: 7.1
        year: 2025
    critical_lists: []
    recycling: 'USGS feldspar chapter: feldspar and nepheline syenite are not recycled by producers; glass container producers use cullet, which reduces feldspar consumption.'
    substitutes:
      - 'USGS: feldspar can be replaced in some end uses by clays, electric furnace slag, feldspar-silica mixtures, pyrophyllite, spodumene, or talc.'
    source: usgs-mcs2026-feldspar
    where: World Mine Production and Reserves table, mine production 2025 (world total 31,000 thousand t, rounded; shares calculated by Space Mushroom against that total); Recycling; Substitutes
media: []
documents:
  - title: NASA/TM-2010-216446, Lunar Regolith Simulant User's Guide (Schrader et al., September 2010)
    type: report
    url: https://ntrs.nasa.gov/api/citations/20100038451/downloads/20100038451.pdf
    year: 2010
  - title: NASA/TM-20240011783, Lunar Regolith Simulant User's Guide, Revision A (Slabic et al., effective 10/24/2024)
    type: report
    url: https://ntrs.nasa.gov/api/citations/20240011783/downloads/Lunar_Regolith_Simulant_Users_Guide_Rev_A_28OCT.pdf
    year: 2024
  - title: NASA Lunar Regolith Simulant Program (Edmunson et al., 3-page abstract)
    type: report
    url: https://ntrs.nasa.gov/api/citations/20100017474/downloads/20100017474.pdf
    year: 2010
  - title: NASA JSC ARES, NU-LHT simulant page with Geomechanical Properties table
    type: report
    url: https://ares.jsc.nasa.gov/projects/simulants/nu-lht.html
  - title: Mineral Commodity Summaries 2026, Feldspar and Nepheline Syenite (USGS)
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-feldspar.pdf
    year: 2026
  - title: PubChem, Silica (CID 24261), Safety and Hazards, GHS Classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/24261/JSON?heading=GHS+Classification
  - title: OSHA, Crystalline Silica topic page
    type: report
    url: https://www.osha.gov/silica-crystalline
  - title: 29 CFR 1910.1053, Respirable crystalline silica (general industry)
    type: standard
    url: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1053
  - title: RF Metrology of Lunar Highlands Regolith Simulant NU-LHT-2M (Johnson, Eckman, Swank, Zemba, 2023)
    type: report
    url: https://ntrs.nasa.gov/citations/20230013296
    year: 2023
gaps:
  - No NU-LHT-2M-specific corrosion or moisture-uptake value was found. The ageing entries are the 2024 guide's general statements for all simulants, and their ratings (moderate) are the assistant's judgment, as the guide gives none.
  - 'Cohesion is not reported for NU-LHT-2M in any source read: the 2024 guide prints n/a (Table 19) and the ARES table shows a dash in the cohesion column.'
  - The friction angle of 36 to 40.7 degrees comes from the ARES page only, which cites Zeng et al. (2010); the 2024 guide prints n/a for it. Both are kept, and the primary Zeng paper was not opened.
  - No safety data sheet or PubChem GHS record for NU-LHT-2M itself was found. The GHS entry is for cristobalite, a silica phase the 2024 guide names in the simulant; the OSHA entries are its health-effect text.
  - No control measures beyond eye protection, dust avoidance and dry storage are stated in the sources read.
  - 'Supply of NU-LHT-2M: no current producer, stock quantity or price was found. The 2024 guide says the producers no longer manufacture it; the ARES page says the USGS is looking into re-starting its simulant efforts.'
  - Critical-mineral lists (USGS and EU) were not checked for feldspar or the anorthosite feedstock in this run.
  - The feldspar supply entry covers feldspar mineral production, the mineral class of anorthosite; it is not a supply figure for anorthosite or for NU-LHT-2M.
  - Modal mineralogy disagrees between the 2010 and 2024 guides (agglutinates 23.5 modal % against 29.02 wt.%); neither source reconciles the two, so both are kept.
  - The 65, 30 and 5 percent mixing ratio is the design ratio stated in the 2024 guide, not a measured value; the measured modal values are listed as properties.
  - Magnetic susceptibility (Table 22, log units) and the 2024 figure-of-merit summary scores were not added as properties; the composition FoM from the 2010 guide is included.
  - The MDPI Aerospace 2024 paper on NU-LHT-2M (Zanotti et al., doi 10.3390/aerospace11040295) returned 403 Access Denied to automated access, so it was not read. The Zeng 2010 and Martin 2022 papers were not opened.
  - Void ratio, specific gravity and friction angle use snake_case names that are not in spores/property-canon.yaml.
  - The OSHA permissible exposure limit was read through WebFetch of the OSHA 1910.1053 page, because curl to that page was blocked (403), so the quotation is not from raw page text.
  - The NASA abstract (NTRS 20100017474) prints no year in the PDF text; the year 2010 is taken from the NTRS identifier.
sources:
  nasa-tm-2010-216446:
    title: Lunar Regolith Simulant User's Guide (NASA/TM-2010-216446)
    id: NASA/TM-2010-216446, September 2010
    url: https://ntrs.nasa.gov/api/citations/20100038451/downloads/20100038451.pdf
    year: 2010
    kind: report
    license: public domain (NASA)
  nasa-tm-2024-guide:
    title: Lunar Regolith Simulant User's Guide, Revision A (NASA/TM-20240011783)
    id: NASA/TM-20240011783, Rev A effective 10/24/2024
    url: https://ntrs.nasa.gov/api/citations/20240011783/downloads/Lunar_Regolith_Simulant_Users_Guide_Rev_A_28OCT.pdf
    year: 2024
    kind: report
    license: public domain (NASA)
  nasa-lpsc-abstract:
    title: NASA Lunar Regolith Simulant Program (Edmunson et al., 3-page abstract)
    id: NTRS 20100017474 (year not printed in the PDF text)
    url: https://ntrs.nasa.gov/api/citations/20100017474/downloads/20100017474.pdf
    year: 2010
    kind: report
    license: public domain (NASA)
  nasa-ares-nu-lht:
    title: NU-LHT simulant page, NASA JSC Astromaterials Research and Exploration Science (ARES), with Geomechanical Properties table
    id: NASA JSC ARES simulants page for NU-LHT; geomechanical table cites Zeng et al. (2010)
    url: https://ares.jsc.nasa.gov/projects/simulants/nu-lht.html
    kind: web
    license: NASA website (cited, not reproduced)
  usgs-mcs2026-feldspar:
    title: Mineral Commodity Summaries 2026, Feldspar and Nepheline Syenite (USGS)
    id: USGS Mineral Commodity Summaries 2026, feldspar chapter
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-feldspar.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  pubchem-silica-ghs:
    title: PubChem, Silica (CID 24261), Safety and Hazards, GHS Classification (ECHA entries)
    id: PubChem CID 24261; ECHA C&L Inventory entries as shown on PubChem
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/24261/JSON?heading=GHS+Classification
    kind: database
    license: PubChem (NIH), data as shown
  osha-silica-page:
    title: OSHA, Crystalline Silica (topic page)
    id: osha.gov/silica-crystalline
    url: https://www.osha.gov/silica-crystalline
    kind: web
    license: public domain (US government)
  osha-1910-1053:
    title: 29 CFR 1910.1053, Respirable crystalline silica (general industry)
    id: 29 CFR 1910.1053
    url: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1053
    kind: standard
    license: public domain (US government)
  johnson2023-ntrs:
    title: RF Metrology of Lunar Highlands Regolith Simulant NU-LHT-2M (Johnson, Eckman, Swank, Zemba, 2023)
    id: NASA NTRS 20230013296
    url: https://ntrs.nasa.gov/citations/20230013296
    year: 2023
    kind: report
    license: public domain (NASA)
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 33
  unreachable: 0
  caveats: 2
  note: Written by an AI assistant from nine sources read in this run (three NASA guides and report pages, the NASA JSC ARES simulant page, the USGS feldspar chapter, PubChem and two OSHA pages). The MDPI open paper returned 403 and was not read. Values are as printed; discrepancies are shown side by side.
story:
  recipe:
    line: NU-LHT-2M is a physical mixture, not one compound. Its crystalline part is Stillwater anorthosite and norite with minor synthetic whitlockite, fluorapatite and pyrite. Its pseudo-agglutinate is made from Stillwater mill sand in a plasma arc, and its good glass is a synthetic glass with a highlands-like composition.
    parts:
      - name: Stillwater anorthosite and norite (crystalline)
        share: 65% crystalline (design mixing ratio)
        role: The dominant rocks in the mix. Plagioclase, pyroxene and olivine make up the crystalline part, as the 2010 and 2024 modal tables show.
      - name: Pseudo-agglutinate
        share: 30% (design mixing ratio)
        role: Glass-bonded fragments made from Stillwater mill sand in a plasma arc. The 2010 guide counts them as agglutinates.
      - name: Good glass
        share: 5% (design mixing ratio)
        role: Glass with no mineral inclusions, per the 2024 guide.
      - name: Minor synthetic minerals
        share: not stated
        role: Synthetic whitlockite, fluorapatite and pyrite (troilite substitute), included in -2M and not in -1M.
  risk_groups:
    - title: For people
      level: 0
      verdict: 'Dust is the concern: silica is present at low levels'
      lead: The 2024 guide says the primary exposure concerns for simulant users are crystalline silica and total dust.
      points:
        - label: Silica content
          line: Table 25 gives 0.67 wt.% total crystalline silica (DCM 2023) and 0.82 wt.% (Herndon 2021) for NU-LHT-2M. The respirable crystalline silica is 0.07 wt.% (DCM 2023).
        - label: Illness
          line: The guide says chronic inhalation of respirable particles below 10 microns can lead to pneumoconiosis, including silicosis, after years of exposure.
        - label: Dust in work
          line: Crystalline silica can become airborne when workers chip, cut, drill or grind objects that contain silica.
    - title: In ISRU processing
      lead: The 2010 guide names the phosphates and sulfides as a possible hazard for ISRU processes.
      points:
        - label: Minerals
          line: Table 8 says the phosphates and sulfides in NU-LHT-2M are realistic but possibly hazardous to ISRU processes. The table does not say how.
        - label: Oxygen production
          line: Table 8 rates NU-LHT-2M most recommended for highlands oxygen production, with slightly low FeO (about 4 against 5 wt.%). It also says the high iron in its silicates will slow reduction.
    - title: Handling and storage
      points:
        - label: Eye protection
          line: The 2024 guide says glasses or goggles are needed depending on the simulant's physical characteristics.
        - label: Airborne dust
          line: Silica-bearing material becomes airborne when it is chipped, cut, drilled or ground.
  why: NU-LHT-2M is a NASA and USGS lunar highlands simulant. It was built to match the average composition, particle size and particle shape of Apollo 16 sample 64001/64002, and it was the prototype version of the NU-LHT series. The 2024 guide says only very small amounts remain for NASA testing.
  uses:
    - where: Excavation and drilling
      line: The 2010 guide rates NU-LHT-2M recommended for excavation and flow, and recommended for drilling and abrasion testing, because its mineral and glass percentages should give realistic abrasiveness.
    - where: Oxygen production (in-situ resource utilization)
      line: The 2010 guide rates NU-LHT-2M most recommended for highlands oxygen production, because its FeO is slightly low against the lunar reference (about 4 against 5 wt.%), but it warns that its phosphates and sulfides may be hazardous to ISRU processes.
    - where: Human health studies
      line: The 2010 guide rates NU-LHT-2M the most suitable composition for human health studies, with a reasonable particle size distribution that is too coarse in the fine fraction.
  can_do:
    - label: Density
      benchmark: density
      line: Bulk density ranges from 1.37 to 2.06 g/cm3 for NU-LHT-2M, as printed in the 2024 guide Table 16. The two Apollo 16 regolith rows in Table 15 are listed as separate properties of this profile.
    - label: Particle size
      benchmark: particle_size_q50
      line: The median particle size (Q50) is 125.7 µm, with Q25 at 55.9 µm and Q75 at 244.5 µm, as printed in Table 10 (Clark 2021).
    - label: Particle shape
      benchmark: aspect_ratio
      line: The bulk aspect ratio is 0.63 and the root form factor 0.91 (Table 13, SDL 2022). The 2010 guide's QEMSCAN count gives 52.8 wt.% rounded particles (Table 6).
    - label: Composition
      benchmark: bulk_sio2
      line: Bulk SiO2 is 47 wt.% and bulk Al2O3 is 24.5 wt.% (Table 7, Wilson USGS 2020). The composition figure of merit against the Apollo 64001/64002 reference is 0.55 (Table 3, 2010 guide).
  compare: 'NU-LHT-2M sits at the highlands end of the NU-LHT family. On the 2010 composition figure of merit it scores 0.55 against lunar reference 64001/64002. The same table ranks it above every other simulant listed except NU-LHT-1M, which scores higher (Table 3). Its median particle size is 125.7 µm (Table 10). The two Apollo 16 density rows in Table 15 disagree, and the NU-LHT-2M density range is printed alongside them (Table 16). The reference FeO is also not settled: the 2024 guide gives 6.6 wt.% for the Apollo highlands average (Table 6), while the 2010 guide cites about 5 wt.% for its lunar reference. Cohesion is not reported for this simulant. The NASA JSC ARES page gives a triaxial friction angle of 36 to 40.7 degrees (Zeng et al. 2010), where the 2024 guide prints n/a (Table 19).'
  compare_rows:
    - label: Bulk density range
      benchmark: density
    - label: Median particle size, Q50
      benchmark: particle_size_q50
    - label: Composition figure of merit
      benchmark: fom_composition_score
  handling:
    - 'Treat dust as a health concern: the guide reports 0.67 wt.% total crystalline silica and 0.07 wt.% respirable crystalline silica.'
    - Wear eye protection suited to the simulant's physical form, as the 2024 guide advises.
    - Keep the dust from becoming airborne when cutting, drilling or grinding silica-bearing objects.
    - Only very small amounts remain for NASA testing, so check availability before planning a test.
    - Store the simulant dry under active humidity control, or desiccate it first (2024 guide, Section 6.2.1).
  good_for:
    - 'Highlands-like composition: bulk SiO2 of 47 wt.% and Al2O3 of 24.5 wt.% (Table 7, Wilson USGS 2020).'
    - Oxygen-production and excavation studies, which the 2010 guide rates recommended for this composition (Tables 7 and 8).
  watch_out:
    - Cohesion is not reported for NU-LHT-2M, and the 2024 guide prints n/a for its friction angle (Table 19). The ARES page gives 36 to 40.7 degrees, a value the 2024 guide does not reconcile.
    - 'Supply is nearly exhausted: the 2024 guide says the producers no longer manufacture this simulant.'
    - Phosphates and sulfides may be hazardous to ISRU processes (Table 8, 2010 guide).
  verdict: NU-LHT-2M is a well-documented highlands simulant in these three NASA guides, with composition, particle size, shape and density data. Its supply is nearly exhausted and its cohesion is not reported, so new test programmes should check availability first.