{
  "spore": "profile",
  "id": "li-900-tile",
  "spore_version": "0.2",
  "family": "silica",
  "name": "LI-900 silica tile (shuttle HRSI)",
  "abbreviation": "LI-900",
  "role": "Reusable surface insulation tile (black HRSI on the Space Shuttle orbiter)",
  "category": "thermal-protection",
  "type": "reusable-tiles",
  "summary": "LI-900 is a rigid tile of silica glass fibre that was the black high-temperature reusable surface insulation (HRSI) on Space Shuttle orbiters. NASA's TPSX database gives a density of 1.44e+02 kg/m^3 for the uncoated tile and a through-thickness thermal conductivity of 4.76e-02 W/m-K, both marked as measured. TPSX also gives a predicted multiple-use temperature limit of 1.59e+03 K. Wikipedia says a typical Shuttle carried about 20,000 HRSI LI-900 tiles, and that optimising the tile's thermal properties reduced its overall strength.\n",
  "best_for": "Reusable insulation on the hot underside of a re-entering vehicle, where very low density and low thermal conductivity matter more than strength (Wikipedia states the design aim as minimising thermal conductivity while giving maximum thermal shock resistance)",
  "weakest_at": "Strength. TPSX gives a tensile strength of 1.65e+05 Pa through the thickness at room temperature, and Wikipedia says the tile is unsuitable for high-stress areas such as around the landing gear doors and windows",
  "identity": {
    "formula": "Silica (SiO2) glass fibre tile: 100% SiO2 per TPSX; 99.9% pure silica glass fibres per Wikipedia",
    "designations": [
      {
        "system": "Trade name",
        "code": "LI-900",
        "note": "Rigid tile",
        "source": "tpsx-li900",
        "where": "Material name field, 'LI-900 Rigid Tile'"
      }
    ],
    "source": "tpsx-li900",
    "where": "Material name and Composition fields (TPSX Material id 1); the composition is also stated in the Wikipedia LI-900 article"
  },
  "tags": {
    "environments": [
      "re-entry"
    ],
    "stresses": [],
    "applications": [
      "heat-shields",
      "thermal-control"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Bulk density, uncoated tile",
      "value": 144,
      "bound": "exact",
      "unit": "kg/m^3",
      "scope": "material",
      "conditions": {
        "state": "uncoated tile",
        "standard_conditions": "TPSX STP flag TRUE for the density row",
        "uncertainty": "2.11e+00 kg/m^3 as printed"
      },
      "method": "Measured value on the TPSX property table (source column: measured; interpolated(T) flag as printed)",
      "status": "ground",
      "source": "tpsx-li900",
      "where": "Properties at Standard Conditions (SI units) table, row Density, ref 1",
      "source_detail": {
        "title": "LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1)",
        "id": "TPSX Material id=1; property rows dated 2006-01-05 on the page",
        "url": "https://tpsx.arc.nasa.gov/Material?id=1",
        "year": 2006,
        "kind": "database",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "density",
      "label": "Bulk density, stated in article",
      "value": 144.2,
      "bound": "exact",
      "unit": "kg/m^3",
      "scope": "material",
      "conditions": {
        "basis": "stated as 9 lb/ft3 in the same sentence"
      },
      "method": "Stated value in the Stated properties list of the Wikipedia LI-900 article",
      "status": "ground",
      "note": "The Wikipedia Space Shuttle TPS article gives 140 kg/m3 in its text and 144 kg/m3 in its density table, so the sources differ by a rounding step.",
      "source": "wiki-li900",
      "where": "Stated properties, Bulk density",
      "source_detail": {
        "title": "LI-900 (Wikipedia article)",
        "id": "Wikipedia article, accessed 2026-11-01",
        "url": "https://en.wikipedia.org/wiki/LI-900",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, through the thickness",
      "value": 0.0476,
      "bound": "exact",
      "unit": "W/m-K",
      "scope": "material",
      "conditions": {
        "direction": "through the thickness",
        "regime": "dynamic values for transient environments (as the TPSX row notes)",
        "uncertainty": "8.57e-03 W/m-K as printed"
      },
      "method": "Measured value on the TPSX property table (source column: measured; STP flag TRUE)",
      "status": "ground",
      "source": "tpsx-li900",
      "where": "Properties at Standard Conditions table, row Thermal Conductivity (Thru-the-Thickness), ref 4",
      "source_detail": {
        "title": "LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1)",
        "id": "TPSX Material id=1; property rows dated 2006-01-05 on the page",
        "url": "https://tpsx.arc.nasa.gov/Material?id=1",
        "year": 2006,
        "kind": "database",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "emissivity",
      "label": "Emissivity, uncoated tile",
      "value": 0.88,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "state": "uncoated tile",
        "temperature": "room temperature measured; higher temperatures extrapolated (TPSX note)",
        "uncertainty": "4.40e-02 as printed"
      },
      "method": "Measured at room temperature on the TPSX property table, ref 3",
      "status": "ground",
      "note": "The value is for the uncoated tile. The black flight tile carries a coating, and no emissivity for the coated tile was found in our sources.",
      "source": "tpsx-li900",
      "where": "Properties at Standard Conditions table, row Emissivity, ref 3",
      "source_detail": {
        "title": "LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1)",
        "id": "TPSX Material id=1; property rows dated 2006-01-05 on the page",
        "url": "https://tpsx.arc.nasa.gov/Material?id=1",
        "year": 2006,
        "kind": "database",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "cte",
      "value": 4.05e-7,
      "bound": "exact",
      "unit": "1/K",
      "scope": "material",
      "conditions": {
        "basis": "isotropic, assumed by TPSX",
        "uncertainty": "4.86e-08 1/K as printed"
      },
      "method": "Measured value on the TPSX property table (source column: measured; STP flag TRUE)",
      "status": "ground",
      "source": "tpsx-li900",
      "where": "Properties at Standard Conditions table, row Coefficient of Thermal Expansion (Isotropic), ref 6",
      "source_detail": {
        "title": "LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1)",
        "id": "TPSX Material id=1; property rows dated 2006-01-05 on the page",
        "url": "https://tpsx.arc.nasa.gov/Material?id=1",
        "year": 2006,
        "kind": "database",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "value": 1.13,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "frequency": "10 GHz",
        "temperature": "room temperature",
        "uncertainty": "5.65e-03 as printed"
      },
      "method": "Measured value on the TPSX property table (source column: measured; flag nonstp as printed)",
      "status": "ground",
      "source": "tpsx-li900",
      "where": "Properties at Standard Conditions table, row Dielectric Constant, ref 6",
      "source_detail": {
        "title": "LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1)",
        "id": "TPSX Material id=1; property rows dated 2006-01-05 on the page",
        "url": "https://tpsx.arc.nasa.gov/Material?id=1",
        "year": 2006,
        "kind": "database",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "dissipation_factor",
      "label": "Loss tangent",
      "value": 0.0004,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "frequency": "10 GHz",
        "temperature": "room temperature",
        "uncertainty": "2.00e-05 as printed"
      },
      "method": "Measured value on the TPSX property table (source column: measured; flag nonstp as printed)",
      "status": "ground",
      "source": "tpsx-li900",
      "where": "Properties at Standard Conditions table, row Loss Tangent, ref 6",
      "source_detail": {
        "title": "LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1)",
        "id": "TPSX Material id=1; property rows dated 2006-01-05 on the page",
        "url": "https://tpsx.arc.nasa.gov/Material?id=1",
        "year": 2006,
        "kind": "database",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, as stated in the TPSX notes",
      "value": 1978,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "basis": "approximate; printed as 'melts at about 1978K (3100F)'"
      },
      "method": "Stated in the TPSX notes on the temperature limit rows, not a separate measured row",
      "status": "ground",
      "source": "tpsx-li900",
      "where": "Properties at Standard Conditions table, notes on rows Multiple Use and Single Use Temperature Limit",
      "source_detail": {
        "title": "LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1)",
        "id": "TPSX Material id=1; property rows dated 2006-01-05 on the page",
        "url": "https://tpsx.arc.nasa.gov/Material?id=1",
        "year": 2006,
        "kind": "database",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "softening_temperature",
      "label": "Softening onset, as stated in the TPSX notes",
      "value": 1644,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "basis": "the material softens above this temperature; printed as '1644K (2500F)'"
      },
      "method": "Stated in the TPSX notes on the temperature limit rows, not a separate measured row",
      "status": "ground",
      "source": "tpsx-li900",
      "where": "Properties at Standard Conditions table, notes on rows Multiple Use and Single Use Temperature Limit",
      "source_detail": {
        "title": "LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1)",
        "id": "TPSX Material id=1; property rows dated 2006-01-05 on the page",
        "url": "https://tpsx.arc.nasa.gov/Material?id=1",
        "year": 2006,
        "kind": "database",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Reuse temperature, 1972 NASA program",
      "value": 1648,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "material": "LI-900 with its coating",
        "basis": "program test results as summarised in the report conclusions; printed as '1648°K (2500°F)'",
        "text_source": "OCR text layer of the NTRS PDF"
      },
      "method": "Stated in the report conclusions as a summary of program tests, not a separate table row",
      "status": "ground",
      "source": "ntrs-19740020226",
      "where": "Conclusions, Volume 1 (OCR text layer)",
      "source_detail": {
        "title": "Development and Design Application of Rigidized Surface Insulation Thermal Protection Systems, Volume 1",
        "id": "NTRS 19740020226; NASA-CR-134326; LMSC-D282673-VOL-1; contract NAS9-12856; published 30 December 1972 per NTRS record",
        "url": "https://ntrs.nasa.gov/citations/19740020226",
        "year": 1972,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Black HRSI tile protection limit",
      "value": 1260,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "tile": "black HRSI tile on the Space Shuttle orbiter underside",
        "basis": "printed as '1,260 °C (2,300 °F)' in the Wikipedia TPS article"
      },
      "method": "Stated in the Wikipedia TPS article as a design statement, not a test row",
      "status": "flight",
      "source": "wiki-tps",
      "where": "Black HRSI tile statement, Space Shuttle thermal protection system article",
      "source_detail": {
        "title": "Space Shuttle thermal protection system (Wikipedia article)",
        "id": "Wikipedia article, accessed 2026-11-01",
        "url": "https://en.wikipedia.org/wiki/Space_Shuttle_thermal_protection_system",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
      }
    },
    {
      "benchmark": "porosity",
      "label": "Air volume fraction, as stated in the Wikipedia article",
      "value": 94,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "by volume; printed as '94% air by volume' in the composition sentence"
      },
      "method": "Stated in the Wikipedia LI-900 article text, not a measured row",
      "status": "ground",
      "source": "wiki-li900",
      "where": "Article text, composition sentence",
      "source_detail": {
        "title": "LI-900 (Wikipedia article)",
        "id": "Wikipedia article, accessed 2026-11-01",
        "url": "https://en.wikipedia.org/wiki/LI-900",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Repeated re-entry heating and reuse",
      "headline": "The 1972 NASA program reports that LI-900 with its coating can be reused to 1648K (2500F) without significant loss of mechanical or thermal performance.",
      "effect": "The report's conclusions say the LI-900 material and coating system has reuse capability to 1648K (2500F), and that its mechanical and thermal performances do not significantly degrade with use. It adds that the strength properties are not appreciably affected by high-temperature reuse.",
      "rating": "low",
      "conditions": {
        "basis": "program test results as summarised in the report conclusions",
        "material": "LI-900 with its coating",
        "text_source": "OCR text layer of the NTRS PDF; the scan was not checked visually"
      },
      "source": "ntrs-19740020226",
      "where": "Conclusions, Volume 1 (OCR text layer)"
    },
    {
      "environment": "Water in tiles that are not waterproofed, during ascent and re-entry",
      "headline": "High water content in non-waterproofed tiles can cause a slight loss of coating during ascent and re-entry.",
      "effect": "The report says the slight coating loss had no effect on heat-shielding capability.",
      "rating": "low",
      "conditions": {
        "tile": "non-waterproofed, high water content",
        "environment": "ascent and re-entry thermal and pressure environment",
        "text_source": "OCR text layer of the NTRS PDF"
      },
      "source": "ntrs-19740020226",
      "where": "Summary, coating compatibility paragraph (OCR text layer)"
    },
    {
      "environment": "Cold soak followed by a re-entry heat pulse",
      "headline": "A cold soak at 116K (-250F) followed by a re-entry heat pulse had no effect on the LI-900 material, according to the 1972 report.",
      "effect": "The report says LI-900 and its coating are compatible and, because of their low thermal expansion, the materials are thermally shock-resistant.",
      "rating": "low",
      "conditions": {
        "cold_soak": "116K (-250F) as printed",
        "text_source": "OCR text layer of the NTRS PDF; the OCR reads the cold-soak temperature with some error"
      },
      "source": "ntrs-19740020226",
      "where": "Summary, coating compatibility paragraph (OCR text layer)"
    },
    {
      "environment": "Quench from high temperature into cold water",
      "headline": "Wikipedia says the tile can be heated to 1,204°C and plunged into cold water without damage.",
      "effect": "The article gives this as a stated property. It is a single statement about thermal shock; the article gives no cycle count or test series.",
      "rating": "low",
      "conditions": {
        "temperature": "1,204°C (1,477K; 2,199F) as printed",
        "medium": "cold water"
      },
      "source": "wiki-li900",
      "where": "Stated properties list"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem reports that vitreous silica (EC 262-373-8) does not meet GHS hazard criteria, as 1614 of 1682 company reports say. This describes the silica substance, not the LI-900 tile, for which we found no safety data sheet.",
        "ghs": [],
        "source": "pubchem-sio2",
        "where": "Safety and Hazards, GHS Classification, ECHA entry 'Silica, vitreous' (ref. 102)"
      },
      {
        "text": "PubChem lists amorphous silica (EC 601-216-3) as an irritant with pictogram GHS07 and signal word Warning. Its hazard statements are H315 (causes skin irritation), H319 (causes serious eye irritation) and H335 (may cause respiratory irritation), aggregated from 2540 company reports.",
        "ghs": [
          "H315",
          "H319",
          "H335"
        ],
        "source": "pubchem-sio2",
        "where": "Safety and Hazards, GHS Classification, ECHA entry 'AMORPHOUS SILICA' (ref. 100)"
      },
      {
        "text": "PubChem lists cristobalite, a crystalline form of silica (EC 238-455-4), as Danger with pictogram GHS08. Its hazard statements are H350 (may cause cancer) and H372 (causes damage to organs through prolonged or repeated exposure). Wikipedia describes LI-900 as silica glass fibres, so this crystalline-form entry is not applied to the tile.",
        "ghs": [
          "H350",
          "H372"
        ],
        "source": "pubchem-sio2",
        "where": "Safety and Hazards, GHS Classification, ECHA entry 'Cristobalite' (ref. 98)"
      }
    ],
    "failure_risks": [
      {
        "mode": "Low strength in high-stress areas",
        "trigger": "Use in high-stress areas such as around the landing gear doors and windows",
        "consequence": "Wikipedia says optimising the tile's thermal properties reduced its overall strength, so the tile was unsuitable for those areas.",
        "severity": "high",
        "source": "wiki-li900",
        "where": "Problems section"
      },
      {
        "mode": "Softening at high temperature",
        "trigger": "Exposure above the multiple-use temperature limit",
        "consequence": "TPSX says the tile softens above 1644K (2500F) and melts at about 1978K (3100F). Its predicted multiple-use limit is 1.59e+03 K.",
        "severity": "high",
        "source": "tpsx-li900",
        "where": "Properties at Standard Conditions table, notes on rows Multiple Use and Single Use Temperature Limit"
      },
      {
        "mode": "Coating loss from water in the tile",
        "trigger": "High water content in a tile that is not waterproofed, during ascent or re-entry",
        "consequence": "A slight loss of coating. The report says there was no effect on heat-shielding capability.",
        "severity": "low",
        "source": "ntrs-19740020226",
        "where": "Summary, coating compatibility paragraph (OCR text layer)"
      },
      {
        "mode": "Tension failure at the strain isolation pad of the HRSI system",
        "trigger": "Stepped tension loading of an HRSI specimen, examined by microscope at each load step",
        "consequence": "A local failure occurred that the authors associate with load transfer through transverse fibres in the strain isolation pad (SIP), the tension failure mode of SIP behaviour.",
        "severity": "moderate",
        "source": "ntrs-tm81821",
        "where": "Abstract (NTRS TM-81821)"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Each tile is fitted individually. The Wikipedia Space Shuttle TPS article says about 24,300 unique tiles were individually fitted on the vehicle.",
        "source": "wiki-tps",
        "where": "Detailed description"
      },
      {
        "text": "Keep water out of tiles that are not waterproofed. The 1972 report links high water content to a slight coating loss during ascent and re-entry.",
        "source": "ntrs-19740020226",
        "where": "Summary (OCR text layer)"
      }
    ],
    "mitigations": [
      {
        "text": "The strain arrestor plate reduces tile and coating stresses under all load and temperature conditions, according to the 1972 report.",
        "source": "ntrs-19740020226",
        "where": "Summary, strain arrestor plate paragraph (OCR text layer)"
      }
    ]
  },
  "uses": [
    {
      "application": "heat-shields",
      "device": "Black high-temperature reusable surface insulation (HRSI) tiles on the Space Shuttle orbiter underside",
      "example": "A typical Shuttle carried about 20,000 HRSI LI-900 tiles. Black tiles have higher emissivity, so they shed heat faster, which helps maximise heat rejection during re-entry.",
      "source": "wiki-li900",
      "where": "Black and white tiles section"
    },
    {
      "application": "thermal-control",
      "device": "White low-temperature reusable surface insulation (LRSI) tiles on the upper surface",
      "example": "The white LI-900 tiles have higher thermal reflectivity and face the sun to reduce solar gain. A typical Shuttle carried about 725 LRSI LI-900 tiles.",
      "source": "wiki-li900",
      "where": "Black and white tiles section; use on the Space Shuttle orbiter"
    },
    {
      "application": "heat-shields",
      "device": "All-silica rigidized surface insulation (RSI) thermal protection system concept for the Space Shuttle",
      "example": "The 1972 NASA report presents the materials and design technology for the all-silica LI-900 RSI TPS concept and says the tile demonstrated that it meets Space Shuttle mission and life requirements.",
      "source": "ntrs-19740020226",
      "where": "Abstract and conclusions (OCR text layer)"
    }
  ],
  "supply": [
    {
      "subject": "Industrial silica sand (quartz sand, the feedstock for silica glass)",
      "abundance": "USGS: quartz-rich sand and sandstone, the main sources of industrial silica sand, occur throughout the world. The US reserve is rated Large.",
      "producers": [
        {
          "country": "United States",
          "share_percent": 27.9,
          "year": 2025
        },
        {
          "country": "China",
          "share_percent": 21.4,
          "year": 2025
        },
        {
          "country": "Netherlands",
          "share_percent": 15.8,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: about 33% of glass containers are recycled, and recycled cullet is a significant proportion of reused silica.",
      "substitutes": [
        "USGS: alternatives for glassmaking, foundry and molding sands are chromite, olivine, staurolite and zircon sands."
      ],
      "source": "usgs-mcs2026-sand",
      "where": "World Mine Production and Reserves table, 2025 column in thousand metric tons (world total printed as 430,000, rounded). Shares calculated by Space Mushroom: 120,000, 92,000 and 68,000 divided by 430,000. Recycling and Substitutes sections. USGS also gives Canada as 84% of US imports, 2021 to 2024."
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "NASA Ames TPSX record: LI-900 Rigid Tile (Material id 1)",
      "type": "database",
      "url": "https://tpsx.arc.nasa.gov/Material?id=1",
      "year": 2006
    },
    {
      "title": "Development and Design Application of Rigidized Surface Insulation Thermal Protection Systems, Volume 1 (NTRS 19740020226, PDF)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/19740020226/downloads/19740020226.pdf",
      "year": 1972
    },
    {
      "title": "Silicon dioxide, PubChem CID 24261 (Safety and Hazards, GHS Classification)",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Silicon-dioxide",
      "year": 2026
    },
    {
      "title": "Mineral Commodity Summaries 2026, Sand and Gravel (Industrial), USGS",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-sand-industrial.pdf",
      "year": 2026
    },
    {
      "title": "NASA TP-3276, Prediction of Rigid Silica Based Insulation Conductivity (NTRS 19930008736, PDF)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/19930008736/downloads/19930008736.pdf",
      "year": 1993
    },
    {
      "title": "NASA TM-81821, Microstructural characterization of the HRSI thermal protection system (NTRS 19800015948, PDF)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/19800015948/downloads/19800015948.pdf",
      "year": 1980
    }
  ],
  "gaps": [
    "Supply: no producer, capacity or critical-mineral listing for the LI-900 tile maker was found. The supply section gives USGS world industrial sand figures as feedstock context, not LI-900 production. No critical-mineral list entry for silica was read in this run.",
    "Hazards: no safety data sheet exists in our sources for LI-900 itself. The hazard entries use PubChem ECHA records for vitreous and amorphous silica, which describe the substance, not the tile. The crystalline (cristobalite) entry is listed for completeness and is not applied to the tile.",
    "Emissivity of the coated black flight tile: TPSX gives 8.80e-01 for the uncoated tile only, and no value for the coated tile was found.",
    "Coating: the composition of the reaction-cured glass (RCG) coating rests on one Wikipedia sentence (tetraboron silicide and borosilicate glass listed). The Wikipedia RCG article returned HTTP 404, and no second source was reached.",
    "Manufacturer: TPSX names United Space Alliance; Wikipedia names Lockheed Missiles and Space Company, and the 1972 report is a Lockheed (LMSC) report. Both are stated side by side; the conflict is not resolved.",
    "Tile counts: Wikipedia LI-900 gives about 20,000 HRSI tiles per typical Shuttle. The Wikipedia Space Shuttle TPS article gives 20,548 HRSI tiles, about 24,300 unique tiles, and 31,000 tiles on Columbia in 1979. These are not reconciled.",
    "Air fraction: 94% by volume (Wikipedia LI-900) against ninety percent empty space (Wikipedia Space Shuttle TPS).",
    "Temperature limits come from different tests and are not converted into one number: 1,260°C for black HRSI tiles (Wikipedia TPS), 1,204°C heat-and-quench (Wikipedia LI-900), 1644K softening (TPSX) and 1648K reuse (1972 report).",
    "Report date: the NTRS record prints 30 December 1972 for ID 19740020226 (NASA-CR-134326, LMSC-D282673-VOL-1, contract NAS9-12856). The ID prefix suggests 1974, so the record date is used.",
    "The 1972 report was read from its OCR text layer. The reuse (1648K), cold-soak (116K) and water statements were not checked against the scanned pages.",
    "Atomic weights for the recipe parts were not printed by any source fetched in this run, so they are left out.",
    "Not found: moisture absorption, a quantified thermal-shock or cycle-life result for LI-900, mechanical data for the coated tile, and flight failure history.",
    "Left out: the TPSX reuse flight limit (100 flights, predicted) and the purchase cost (predicted, per m^2), because cost is not a material property and the flight limit is only predicted.",
    "Media: no image files were fetched, so the media section is left out.",
    "Sources: 8 sources are cited. NASA TP-3276 is cited for its stated method only; no value was taken from it, because its conductivity figures were not readable in this run.",
    "Scientific notation: the new rows leave out TPSX values printed in e-notation (specific heat, in-plane thermal conductivity, emissivity, tensile and compressive strengths, moduli, predicted temperature limits, cost). The existing rows are unchanged.",
    "Property names: softening_temperature and porosity are not in spores/property-canon.yaml, so they use short snake_case names."
  ],
  "story": {
    "why": "LI-900 was developed as a lightweight, all-silica reusable insulation for the Space Shuttle. Lockheed's earlier all-silica material of the same family was tested extensively before LI-900 (1972 NASA report). The program reduced the density to 144 kg/m^3 (9 lb/cu ft) to create LI-900 (NTRS 19740020226). The design trades strength for insulation: TPSX gives a low thermal conductivity, and Wikipedia says optimising the thermal properties reduced the overall strength. NASA Technical Paper 3276 gives a method for predicting the thermal conductivity of this class of silica insulation, and extends it to the upper temperature limits (NTRS 19930008736, abstract).",
    "uses": [
      {
        "where": "Underside of the Space Shuttle (black HRSI tiles)",
        "line": "A typical Shuttle carried about 20,000 HRSI LI-900 tiles, according to Wikipedia. Black tiles have higher emissivity, so they shed heat faster during re-entry."
      },
      {
        "where": "Upper surface of the Space Shuttle (white LRSI tiles)",
        "line": "The white LI-900 tiles have higher thermal reflectivity and face the sun to reduce solar gain. A typical Shuttle carried about 725 LRSI LI-900 tiles, according to Wikipedia."
      },
      {
        "where": "1972 NASA all-silica TPS concept",
        "line": "The 1972 report presents the materials and design technology for the all-silica LI-900 RSI TPS concept and states that the tile demonstrated that it meets Space Shuttle mission and life requirements."
      }
    ],
    "can_do": [
      {
        "label": "Insulation",
        "line": "Through the thickness the tile has a thermal conductivity of 4.76e-02 W/m-K, as printed by TPSX. TPSX marks this as a dynamic value for transient environments.",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      },
      {
        "label": "Temperature",
        "line": "TPSX predicts a multiple-use temperature limit of 1.59e+03 K. Wikipedia says the tile can be heated to 1,204°C and then plunged into cold water without damage.",
        "benchmark": "max_service_temp",
        "scope": "material"
      },
      {
        "label": "Reuse",
        "line": "The 1972 NASA program found that the LI-900 material and coating system can be reused to 1648K (2500F) with no significant degradation of its mechanical and thermal performance (NTRS 19740020226, conclusions).",
        "scope": "material",
        "value": "To 1648K (2500F)"
      },
      {
        "label": "Strength",
        "line": "At room temperature the tensile strength is 1.65e+05 Pa through the thickness (TPSX). Wikipedia says the tile is unsuitable for high-stress areas.",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material"
      }
    ],
    "compare": "Within the NASA and Wikipedia sources, LI-900 trades strength for insulation. Wikipedia says a stronger version of the tile exists, which gives more strength and insulation but carries a considerable weight penalty. Its figures are not included here because they are for a different grade. The table below sets LI-900's density, thermal conductivity and tensile strength side by side.",
    "compare_rows": [
      {
        "label": "Bulk density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity, through the thickness",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      },
      {
        "label": "Tensile strength, through the thickness",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material"
      }
    ],
    "handling": [
      "Each tile is fitted individually. The Wikipedia Space Shuttle TPS article says about 24,300 unique tiles were fitted on the vehicle.",
      "Keep water out of tiles that are not waterproofed. The 1972 report links high water content to a slight coating loss during ascent and re-entry.",
      "Keep high loads away from the tile's high-stress areas. Wikipedia says the tile is unsuitable for the areas around the landing gear doors and windows.",
      "Use a strain arrestor plate between the tile and its bond where the design allows. The 1972 report says it reduces tile and coating stresses under all load and temperature conditions."
    ],
    "good_for": [
      "Low thermal conductivity: 4.76e-02 W/m-K through the thickness (TPSX), the property the tile was designed for.",
      "Reuse at high temperature: the 1972 NASA program reports reuse to 1648K (2500F) without significant degradation.",
      "Thermal shock: the tile can be heated to 1,204°C and plunged into cold water without damage (Wikipedia)."
    ],
    "watch_out": [
      "Low strength: the tensile strength is 1.65e+05 Pa through the thickness (TPSX), and Wikipedia says the tile is unsuitable for high-stress areas.",
      "Coated and uncoated numbers differ in scope. TPSX gives the density and emissivity for the uncoated tile, while the black flight tile is coated.",
      "The sources disagree on tile counts, air fraction and manufacturer. Each value is stated with its source (see gaps)."
    ],
    "verdict": "LI-900 suits reusable insulation where low density and low thermal conductivity matter more than strength. The NASA data support reuse to 1648K (2500F). The emissivity of the coated tile is not in the sources we hold. PubChem classifies the silica substance, but we hold no classification for the LI-900 tile itself.",
    "recipe": {
      "line": "LI-900 is a tile of silica glass fibre with most of its volume taken up by air. Wikipedia says the tile is made from very pure quartz sand, but the sources fetched do not describe how the tiles were made.",
      "parts": [
        {
          "name": "Silica glass fibre",
          "symbol": "SiO2",
          "role": "The solid framework of the tile. Wikipedia says the design aim was to minimise thermal conductivity while giving maximum thermal shock resistance."
        },
        {
          "name": "Air in the pores",
          "role": "Most of the tile volume. Together with the fibre it sets the bulk density of 144 kg/m^3 (9 lb/ft^3)."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "PubChem's ECHA entries cover the silica substance, not the tile. Vitreous silica is reported as not meeting GHS criteria, and amorphous silica is an irritant (H315, H319, H335). We found no safety data sheet for LI-900 itself.",
        "points": [
          {
            "label": "The tile",
            "line": "The TPSX record and the Wikipedia articles describe composition, density and temperature limits, but they say nothing about hazards to people."
          }
        ],
        "level": 0,
        "verdict": "Silica substance only, no tile SDS"
      },
      {
        "title": "On the vehicle",
        "lead": "These are design limits and test results for the tile on the orbiter, not incident reports.",
        "points": [
          {
            "label": "Re-entry heat",
            "line": "The black HRSI tiles were used where the re-entry temperature was below 1,260°C, according to the Wikipedia Space Shuttle TPS article."
          },
          {
            "label": "Softening",
            "line": "TPSX says the tile softens above 1644K (2500F) and melts at about 1978K (3100F)."
          },
          {
            "label": "Strength",
            "line": "Wikipedia says the tile is unsuitable for high-stress areas such as around the landing gear doors and windows."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Storage",
            "line": "The sources fetched in this run give no storage rule for LI-900 (see gaps)."
          },
          {
            "label": "Water",
            "line": "The 1972 report says high water content in tiles that are not waterproofed can cause a slight coating loss during ascent and re-entry."
          }
        ]
      }
    ]
  },
  "updated": "2026-11-01",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 12,
    "unreachable": 1,
    "caveats": 3,
    "note": "Read by an AI assistant on 2026-11-01 from the TPSX record, Wikipedia pages and the NTRS report text. The Wikipedia RCG page returned 404; the NTRS text came from an OCR layer."
  },
  "sources": {
    "tpsx-li900": {
      "title": "LI-900 Rigid Tile, NASA Ames Thermal Protection Materials database record (Material id 1)",
      "id": "TPSX Material id=1; property rows dated 2006-01-05 on the page",
      "url": "https://tpsx.arc.nasa.gov/Material?id=1",
      "year": 2006,
      "kind": "database",
      "license": "public domain (NASA)"
    },
    "wiki-li900": {
      "title": "LI-900 (Wikipedia article)",
      "id": "Wikipedia article, accessed 2026-11-01",
      "url": "https://en.wikipedia.org/wiki/LI-900",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
    },
    "wiki-tps": {
      "title": "Space Shuttle thermal protection system (Wikipedia article)",
      "id": "Wikipedia article, accessed 2026-11-01",
      "url": "https://en.wikipedia.org/wiki/Space_Shuttle_thermal_protection_system",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
    },
    "ntrs-19740020226": {
      "title": "Development and Design Application of Rigidized Surface Insulation Thermal Protection Systems, Volume 1",
      "id": "NTRS 19740020226; NASA-CR-134326; LMSC-D282673-VOL-1; contract NAS9-12856; published 30 December 1972 per NTRS record",
      "url": "https://ntrs.nasa.gov/citations/19740020226",
      "year": 1972,
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "pubchem-sio2": {
      "title": "Silicon dioxide, PubChem CID 24261 (Safety and Hazards, GHS Classification)",
      "id": "CID 24261; GHS data from ECHA C&L Inventory and NITE-CMC as shown on the page, read 2026-11-01",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Silicon-dioxide",
      "year": 2026,
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "usgs-mcs2026-sand": {
      "title": "Mineral Commodity Summaries 2026, Sand and Gravel (Industrial), USGS",
      "id": "USGS MCS 2026, industrial sand and gravel chapter, 2025 estimates; version read 2026-11-01",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-sand-industrial.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "ntrs-tp3276": {
      "title": "Prediction of Rigid Silica Based Insulation Conductivity (NASA Technical Paper 3276)",
      "id": "NASA TP-3276, January 1993; NTRS 19930008736; Williams and Curry",
      "url": "https://ntrs.nasa.gov/citations/19930008736",
      "year": 1993,
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "ntrs-tm81821": {
      "title": "Microstructural characterization of the HRSI thermal protection system for space shuttle (NASA Technical Memorandum 81821)",
      "id": "NASA TM-81821; NTRS 19800015948; Ransone and Rummler; year taken from the NTRS ID prefix",
      "url": "https://ntrs.nasa.gov/citations/19800015948",
      "year": 1980,
      "kind": "report",
      "license": "public domain (NASA)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/li-900-tile/"
}