{
  "spore": "profile",
  "id": "pica",
  "spore_version": "0.2",
  "family": "carbon-phenolic",
  "name": "Phenolic Impregnated Carbon Ablator",
  "abbreviation": "PICA",
  "role": "Ablative heat shield for atmospheric entry (carbon-fibre preform infused with phenolic resin)",
  "category": "thermal-protection",
  "type": "ablators",
  "summary": "PICA (Phenolic Impregnated Carbon Ablator) is a low-density heat shield made from a rigid carbon-fibre preform, called FiberForm, infused with phenolic resin. The 1998 NASA annual report gives a nominal density of 224 to 248 kg/m^3 for PICA, depending on phenolic loading. PICA was the forebody heat shield of the Stardust sample-return capsule, launched in February 1999, and was used in a tiled layout on Mars Science Laboratory.\n",
  "best_for": "Entry heat shields that need a light carbon-phenolic ablator with flight heritage (Stardust; Mars Science Laboratory in tiled form)",
  "weakest_at": "Supply: the rayon precursor has been replaced at least twice in the past 25 years (Gasch et al.), and the sources read here give no hazard, ageing or humidity data",
  "identity": {
    "formula": "Carbon-fibre substrate (FiberForm) impregnated with phenolic resin (Durite SC-1008); a composite, not a single compound",
    "designations": [],
    "source": "selvaduray1998",
    "where": "Materials section (PICA uses FiberForm and the phenolic resin Durite SC-1008)"
  },
  "tags": {
    "environments": [
      "re-entry"
    ],
    "stresses": [
      "extreme-heat"
    ],
    "applications": [
      "heat-shields"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density range, PICA after phenolic impregnation",
      "value": 224,
      "value_high": 248,
      "bound": "range",
      "unit": "kg/m^3",
      "scope": "material",
      "conditions": {
        "phenolic_loading": "depends on the level of phenolic loading",
        "form": "nominal range for the impregnated preform"
      },
      "method": "Nominal range stated in the 1998 NASA annual report",
      "status": "ground",
      "note": "Printed as 224 to 248 kg/m^3 (14 to 15.5 lb/ft^3).",
      "source": "selvaduray1998",
      "where": "Materials section, paragraph on the nominal density of PICA",
      "source_detail": {
        "title": "Thermal Protection Materials Development, 1997-1998 Annual Report",
        "id": "NASA/CR 208331; NTRS 19980235586; G. Selvaduray and M. Cox, San Jose State University",
        "url": "https://ntrs.nasa.gov/api/citations/19980235586/downloads/19980235586.pdf",
        "year": 1998,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density range, FiberForm substrate before impregnation",
      "value": 144,
      "value_high": 176,
      "bound": "range",
      "unit": "kg/m^3",
      "scope": "material",
      "conditions": {
        "form": "FiberForm carbon-fibre substrate, not impregnated",
        "basis": "nominal range"
      },
      "method": "Nominal range stated in the 1998 NASA annual report",
      "status": "ground",
      "note": "Printed as 144 to 176 kg/m^3 (9.0 to 11 lb/ft^3).",
      "source": "selvaduray1998",
      "where": "Materials section, first density sentence",
      "source_detail": {
        "title": "Thermal Protection Materials Development, 1997-1998 Annual Report",
        "id": "NASA/CR 208331; NTRS 19980235586; G. Selvaduray and M. Cox, San Jose State University",
        "url": "https://ntrs.nasa.gov/api/citations/19980235586/downloads/19980235586.pdf",
        "year": 1998,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat, virgin PICA",
      "value": 1200,
      "bound": "exact",
      "unit": "J/kg-K",
      "scope": "material",
      "conditions": {
        "temperature": "not printed on the page",
        "standard_conditions_flag": "TRUE (TPSX column)"
      },
      "method": "Value listed in the TPSX database; its source column says unknown",
      "status": "ground",
      "note": "Printed as 1.20e+03 J/kg-K.",
      "source": "tpsx-pica",
      "where": "Properties at Standard Conditions table, Specific Heat row",
      "source_detail": {
        "title": "NASA Ames Thermal Protection Materials Database (TPSX): PICA [virgin], Material id 43",
        "id": "TPSX Material id 43; manufacturer Fiber Materials Inc.; point of contact F.S. Milos",
        "url": "https://tpsx.arc.nasa.gov/Material?id=43",
        "year": 2006,
        "kind": "database",
        "license": "NASA public database (cited, not reproduced)"
      }
    },
    {
      "benchmark": "emissivity",
      "label": "Emissivity, virgin PICA",
      "value": 0.8,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "temperature": "not printed on the page",
        "standard_conditions_flag": "assumed/assumed (TPSX column)"
      },
      "method": "Value listed in the TPSX database; its source column says measured",
      "status": "ground",
      "source": "tpsx-pica",
      "where": "Properties at Standard Conditions table, Emissivity row",
      "source_detail": {
        "title": "NASA Ames Thermal Protection Materials Database (TPSX): PICA [virgin], Material id 43",
        "id": "TPSX Material id 43; manufacturer Fiber Materials Inc.; point of contact F.S. Milos",
        "url": "https://tpsx.arc.nasa.gov/Material?id=43",
        "year": 2006,
        "kind": "database",
        "license": "NASA public database (cited, not reproduced)"
      }
    },
    {
      "benchmark": "char_yield",
      "label": "Char yield of the phenolic resin in PICA",
      "value": 0.63,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "atmosphere": "argon gas flow",
        "temperature": "about 1250 K, in a tube furnace",
        "material": "phenolic resin in PICA"
      },
      "method": "Specimens cycled to about 1250 K under argon; the report defines char yield as the mass remaining after pyrolysis",
      "status": "ground",
      "note": "The report defines char yield as a percentage of mass remaining, but prints 0.63 with no unit. The report does not say whether that is a fraction or a percent.",
      "source": "selvaduray1998",
      "where": "Charring paragraph, char yield V of the phenolic resin in PICA",
      "source_detail": {
        "title": "Thermal Protection Materials Development, 1997-1998 Annual Report",
        "id": "NASA/CR 208331; NTRS 19980235586; G. Selvaduray and M. Cox, San Jose State University",
        "url": "https://ntrs.nasa.gov/api/citations/19980235586/downloads/19980235586.pdf",
        "year": 1998,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "centerline_recession",
      "label": "Centerline recession, arc-jet condition 1, model AA-43-209-N",
      "value": 2.33,
      "bound": "exact",
      "unit": "mm",
      "scope": "material",
      "conditions": {
        "condition_number": "1",
        "exposure_time": "55 s",
        "thermocouple_option": "A",
        "heat_flux": "not read: Table 2 is not legible in the extracted text"
      },
      "method": "Arc-jet test of a PICA model; centerline recession measured by the authors",
      "status": "ground",
      "note": "A second model under the same condition, AA-43-210-N, recessed 2.27 mm.",
      "source": "milos2009",
      "where": "Table 4, condition 1, model AA-43-209-N",
      "source_detail": {
        "title": "Ablation and Thermal Response Property Model Validation for Phenolic Impregnated Carbon Ablator",
        "id": "AIAA-2009-0262 (47th AIAA Aerospace Sciences Meeting); NTRS 20110012891; F.S. Milos and Y.-K. Chen, NASA Ames",
        "url": "https://ntrs.nasa.gov/api/citations/20110012891/downloads/20110012891.pdf",
        "year": 2009,
        "kind": "paper",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "centerline_recession",
      "label": "Centerline recession, arc-jet condition 2b, model AT-007",
      "value": 24.72,
      "bound": "exact",
      "unit": "mm",
      "scope": "material",
      "conditions": {
        "condition_number": "2b",
        "exposure_time": "400 s",
        "thermocouple_option": "none",
        "heat_flux": "not read: Table 2 is not legible in the extracted text"
      },
      "method": "Arc-jet test of a PICA model; centerline recession measured by the authors",
      "status": "ground",
      "source": "milos2009",
      "where": "Table 4, condition 2b, model AT-007",
      "source_detail": {
        "title": "Ablation and Thermal Response Property Model Validation for Phenolic Impregnated Carbon Ablator",
        "id": "AIAA-2009-0262 (47th AIAA Aerospace Sciences Meeting); NTRS 20110012891; F.S. Milos and Y.-K. Chen, NASA Ames",
        "url": "https://ntrs.nasa.gov/api/citations/20110012891/downloads/20110012891.pdf",
        "year": 2009,
        "kind": "paper",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "max_surface_temperature",
      "label": "Maximum surface temperature, arc-jet condition 1, model AA-43-209-N",
      "value": 2033,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "condition_number": "1",
        "exposure_time": "55 s",
        "heat_flux": "not read: Table 2 is not legible in the extracted text"
      },
      "method": "Arc-jet test of a PICA model; maximum surface temperature measured by the authors",
      "status": "ground",
      "note": "A second model under the same condition, AA-43-210-N, reached 2041 K.",
      "source": "milos2009",
      "where": "Table 4, condition 1, model AA-43-209-N",
      "source_detail": {
        "title": "Ablation and Thermal Response Property Model Validation for Phenolic Impregnated Carbon Ablator",
        "id": "AIAA-2009-0262 (47th AIAA Aerospace Sciences Meeting); NTRS 20110012891; F.S. Milos and Y.-K. Chen, NASA Ames",
        "url": "https://ntrs.nasa.gov/api/citations/20110012891/downloads/20110012891.pdf",
        "year": 2009,
        "kind": "paper",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "max_surface_temperature",
      "label": "Maximum surface temperature, arc-jet condition 2b, model AT-007",
      "value": 2196,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "condition_number": "2b",
        "exposure_time": "400 s",
        "heat_flux": "not read: Table 2 is not legible in the extracted text"
      },
      "method": "Arc-jet test of a PICA model; maximum surface temperature measured by the authors",
      "status": "ground",
      "source": "milos2009",
      "where": "Table 4, condition 2b, model AT-007",
      "source_detail": {
        "title": "Ablation and Thermal Response Property Model Validation for Phenolic Impregnated Carbon Ablator",
        "id": "AIAA-2009-0262 (47th AIAA Aerospace Sciences Meeting); NTRS 20110012891; F.S. Milos and Y.-K. Chen, NASA Ames",
        "url": "https://ntrs.nasa.gov/api/citations/20110012891/downloads/20110012891.pdf",
        "year": 2009,
        "kind": "paper",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Average density, Lyocell-based PICA (PICA-D)",
      "value": 0.28,
      "bound": "exact",
      "unit": "g/cc",
      "scope": "material",
      "conditions": {
        "precursor": "Lyocell carbon fibre (PICA-D), average of the samples shown"
      },
      "method": "Average value in the Mechanical Property Comparison table of the NASA Ames slides; the slides do not print a test method for density",
      "status": "ground",
      "note": "Printed as 0.28 with unit g/cc.",
      "source": "stackpoole2018",
      "where": "Mechanical Property Comparison table, Density column, Average Lyocell PICA row",
      "source_detail": {
        "title": "Sustaining PICA TPS for Future NASA Robotic Science Missions (slides)",
        "id": "NTRS 20180006865; M. Stackpoole, E. Venkatapathy and M. Gasch, NASA Ames; S. Violette, Fiber Materials Inc.",
        "url": "https://ntrs.nasa.gov/api/citations/20180006865/downloads/20180006865.pdf",
        "year": 2018,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Approximate density, PICA (background section of the slides)",
      "value": 0.27,
      "bound": "exact",
      "unit": "g/cc",
      "scope": "material",
      "conditions": {
        "precursor": "heritage rayon-based PICA, as described in the background section",
        "basis": "approximate"
      },
      "method": "Approximate value given in the background section of the slides",
      "status": "ground",
      "note": "Printed as \"~ 0.27g/cm3\"; the tilde means approximately and is kept from the slide.",
      "source": "stackpoole2018",
      "where": "Background section, first bullet",
      "source_detail": {
        "title": "Sustaining PICA TPS for Future NASA Robotic Science Missions (slides)",
        "id": "NTRS 20180006865; M. Stackpoole, E. Venkatapathy and M. Gasch, NASA Ames; S. Violette, Fiber Materials Inc.",
        "url": "https://ntrs.nasa.gov/api/citations/20180006865/downloads/20180006865.pdf",
        "year": 2018,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity at 100°F, Lyocell-based PICA (PICA-D), average",
      "value": 0.94,
      "bound": "exact",
      "unit": "BTU-in/hr-ft2-oF",
      "scope": "material",
      "conditions": {
        "temperature": "100°F",
        "precursor": "Lyocell carbon fibre (PICA-D), average"
      },
      "method": "Average shown in the Thermal Property Comparison table of the NASA Ames slides; the slides do not print the test method",
      "status": "ground",
      "source": "stackpoole2018",
      "where": "Thermal Property Comparison table, Average Lyocell PICA row, 100°F column",
      "source_detail": {
        "title": "Sustaining PICA TPS for Future NASA Robotic Science Missions (slides)",
        "id": "NTRS 20180006865; M. Stackpoole, E. Venkatapathy and M. Gasch, NASA Ames; S. Violette, Fiber Materials Inc.",
        "url": "https://ntrs.nasa.gov/api/citations/20180006865/downloads/20180006865.pdf",
        "year": 2018,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity at 350°F, Lyocell-based PICA (PICA-D), average",
      "value": 1.32,
      "bound": "exact",
      "unit": "BTU-in/hr-ft2-oF",
      "scope": "material",
      "conditions": {
        "temperature": "350°F",
        "precursor": "Lyocell carbon fibre (PICA-D), average"
      },
      "method": "Average shown in the Thermal Property Comparison table of the NASA Ames slides; the slides do not print the test method",
      "status": "ground",
      "source": "stackpoole2018",
      "where": "Thermal Property Comparison table, Average Lyocell PICA row, 350°F column",
      "source_detail": {
        "title": "Sustaining PICA TPS for Future NASA Robotic Science Missions (slides)",
        "id": "NTRS 20180006865; M. Stackpoole, E. Venkatapathy and M. Gasch, NASA Ames; S. Violette, Fiber Materials Inc.",
        "url": "https://ntrs.nasa.gov/api/citations/20180006865/downloads/20180006865.pdf",
        "year": 2018,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity at 100°F, heritage rayon-based PICA, range",
      "value": 1,
      "value_high": 1.5,
      "bound": "range",
      "unit": "BTU-in/hr-ft2-oF",
      "scope": "material",
      "conditions": {
        "temperature": "100°F",
        "precursor": "heritage rayon-based PICA"
      },
      "method": "Range shown in the Thermal Property Comparison table of the NASA Ames slides",
      "status": "ground",
      "note": "Printed as 1.0 – 1.5 for rayon PICA at 100°F.",
      "source": "stackpoole2018",
      "where": "Thermal Property Comparison table, Rayon PICA row, 100°F column",
      "source_detail": {
        "title": "Sustaining PICA TPS for Future NASA Robotic Science Missions (slides)",
        "id": "NTRS 20180006865; M. Stackpoole, E. Venkatapathy and M. Gasch, NASA Ames; S. Violette, Fiber Materials Inc.",
        "url": "https://ntrs.nasa.gov/api/citations/20180006865/downloads/20180006865.pdf",
        "year": 2018,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "In-plane failure stress, Lyocell-based PICA (PICA-D), average",
      "value": 246,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "orientation": "in-plane (IP)",
        "precursor": "Lyocell carbon fibre (PICA-D), average"
      },
      "method": "Average failure stress in the Mechanical Property Comparison table of the NASA Ames slides; the slides do not name the test standard",
      "status": "ground",
      "note": "The same table prints 160 - 255 for rayon PICA IP properties.",
      "source": "stackpoole2018",
      "where": "Mechanical Property Comparison table, Average failure stress column, IP properties row",
      "source_detail": {
        "title": "Sustaining PICA TPS for Future NASA Robotic Science Missions (slides)",
        "id": "NTRS 20180006865; M. Stackpoole, E. Venkatapathy and M. Gasch, NASA Ames; S. Violette, Fiber Materials Inc.",
        "url": "https://ntrs.nasa.gov/api/citations/20180006865/downloads/20180006865.pdf",
        "year": 2018,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Through-thickness failure stress, Lyocell-based PICA (PICA-D), average",
      "value": 44,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "orientation": "through-thickness (TTT)",
        "precursor": "Lyocell carbon fibre (PICA-D), average"
      },
      "method": "Average failure stress in the Mechanical Property Comparison table of the NASA Ames slides; the slides do not name the test standard",
      "status": "ground",
      "note": "The same table prints 43 to 54 for rayon PICA TTT properties.",
      "source": "stackpoole2018",
      "where": "Mechanical Property Comparison table, Average failure stress column, TTT properties row",
      "source_detail": {
        "title": "Sustaining PICA TPS for Future NASA Robotic Science Missions (slides)",
        "id": "NTRS 20180006865; M. Stackpoole, E. Venkatapathy and M. Gasch, NASA Ames; S. Violette, Fiber Materials Inc.",
        "url": "https://ntrs.nasa.gov/api/citations/20180006865/downloads/20180006865.pdf",
        "year": 2018,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "centerline_recession",
      "label": "Average centerline recession, Lyocell-derived PICA, arc-jet at 1550W/cm2 and 1.3 atm",
      "value": 4,
      "bound": "exact",
      "unit": "mm",
      "scope": "material",
      "conditions": {
        "heat_flux": "1550W/cm2",
        "pressure": "1.3 atm",
        "atmosphere": "air (runs in air, 2017)",
        "precursor": "Lyocell (PICA-D)"
      },
      "method": "Average centerline recession of arc-jet runs, as tabulated on the NASA Ames slides; the exposure time is not printed on the slide",
      "status": "ground",
      "note": "Rayon-derived PICA at the same condition is a separate row.",
      "source": "ellerby2019",
      "where": "PICA-D Arc Jet Testing, Recession Comparison table, Lyocell PICA row, first column",
      "source_detail": {
        "title": "Sustaining Phenolic Impregnated Carbon Ablator (PICA) for Future NASA Missions Including Discovery and New Frontiers",
        "id": "NTRS 20190028929; International Planetary Probe Workshop, 2019; D. Ellerby et al., NASA Ames",
        "url": "https://ntrs.nasa.gov/api/citations/20190028929/downloads/20190028929.pdf",
        "year": 2019,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    },
    {
      "benchmark": "centerline_recession",
      "label": "Average centerline recession, rayon-derived PICA, arc-jet at 1550W/cm2 and 1.3 atm",
      "value": 4.2,
      "bound": "exact",
      "unit": "mm",
      "scope": "material",
      "conditions": {
        "heat_flux": "1550W/cm2",
        "pressure": "1.3 atm",
        "atmosphere": "air (runs in air, 2017)",
        "precursor": "heritage rayon"
      },
      "method": "Average centerline recession of arc-jet runs, as tabulated on the NASA Ames slides; the exposure time is not printed on the slide",
      "status": "ground",
      "note": "Lyocell-derived PICA at the same condition is a separate row.",
      "source": "ellerby2019",
      "where": "PICA-D Arc Jet Testing, Recession Comparison table, Rayon PICA row, first column",
      "source_detail": {
        "title": "Sustaining Phenolic Impregnated Carbon Ablator (PICA) for Future NASA Missions Including Discovery and New Frontiers",
        "id": "NTRS 20190028929; International Planetary Probe Workshop, 2019; D. Ellerby et al., NASA Ames",
        "url": "https://ntrs.nasa.gov/api/citations/20190028929/downloads/20190028929.pdf",
        "year": 2019,
        "kind": "report",
        "license": "NASA NTRS public record (cited, not reproduced)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Arc-jet aerothermal heating, the test conditions in Milos and Chen (2009)",
      "headline": "In two arc-jet conditions, centerline recession was 2.33 mm at 55 s and 24.72 mm at 400 s.",
      "effect": "Recession is the depth of surface material removed. The two rows come from different test conditions, and the heat flux for each condition is not legible in the extracted text, so the two rows are not a rate for PICA. The maximum surface temperature was 2033 K at 55 s and 2196 K at 400 s.",
      "rating": "moderate",
      "conditions": {
        "test": "arc-jet tests of PICA models",
        "heat_flux": "not read for each condition",
        "data": "Table 4 of the paper"
      },
      "source": "milos2009",
      "where": "Table 4 (test conditions, centerline recession and maximum temperature)"
    },
    {
      "environment": "Heating of the phenolic resin to about 1250 K under argon (pyrolysis)",
      "headline": "About 0.63 of the phenolic resin mass remains as char after pyrolysis (printed value, unit not stated).",
      "effect": "The 1998 report uses this char yield for the phenolic resin in PICA. It gives 0.60 for the silicone resin in SIRCA, the silicone-impregnated ceramic ablator the report also tests.",
      "rating": "low",
      "conditions": {
        "atmosphere": "argon gas flow",
        "temperature": "about 1250 K in a tube furnace",
        "material": "phenolic resin in PICA"
      },
      "source": "selvaduray1998",
      "where": "Charring paragraph, char yield V"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "Phenol, the monomer used to make phenolic resins, is classed in PubChem's aggregated GHS record (ECHA C&L notifications) as toxic if swallowed (H301), toxic in contact with skin (H311), causing severe skin burns and eye damage (H314), toxic if inhaled (H331), suspected of causing genetic defects (H341), and causing damage to organs through prolonged or repeated exposure (H373). Serious eye damage (H318) and toxicity to aquatic life (H411) appear in some notifications. This is a different substance from the phenolic resin in PICA (Durite SC-1008, per Selvaduray and Cox 1998). No safety data sheet for PICA or for that resin was read in this run, so this entry describes phenol only.",
        "ghs": [
          "H301",
          "H311",
          "H314",
          "H318",
          "H331",
          "H341",
          "H373",
          "H411"
        ],
        "source": "pubchem-phenol",
        "where": "GHS Classification section, aggregated ECHA C&L data (CID 996)"
      }
    ],
    "failure_risks": [
      {
        "mode": "Surface recession beyond the design depth",
        "trigger": "Arc-jet exposure of 400 s in test condition 2b (Milos and Chen 2009, Table 4)",
        "consequence": "Centerline recession of 24.72 mm and a maximum surface temperature of 2196 K in that test.",
        "severity": "moderate",
        "source": "milos2009",
        "where": "Table 4, condition 2b"
      }
    ],
    "side_effects": [],
    "handling": [],
    "mitigations": []
  },
  "uses": [
    {
      "application": "heat-shields",
      "device": "Stardust sample-return capsule forebody heat shield",
      "example": "PICA was selected as the forebody heat shield for the Stardust Discovery Class Mission, which launched in February 1999 and was to re-enter at 16 Km/sec.",
      "source": "tpsx-pica",
      "where": "Description (summary) on the TPSX Material page"
    },
    {
      "application": "heat-shields",
      "device": "OSIRIS-REx sample-return capsule heat shield",
      "example": "Gasch et al. (2019) report that OSIRIS-REx uses a single-piece PICA heat shield very similar to the Stardust design.",
      "source": "gasch2019",
      "where": "Introduction"
    },
    {
      "application": "heat-shields",
      "device": "Mars Science Laboratory and Mars 2020 entry heat shields (tiled)",
      "example": "PICA was used as the Mars Science Laboratory heat shield in a tiled configuration, and the Mars 2020 heat shield design follows that layout with PICA in a tiled arrangement.",
      "source": "gasch2019",
      "where": "Introduction"
    },
    {
      "application": "heat-shields",
      "device": "Orion Crew Module heat shield (candidate)",
      "example": "Milos and Chen (2009) describe PICA as a candidate heat shield material for the Orion Crew Module, and the Orion program tested newly manufactured PICA.",
      "source": "milos2009",
      "where": "Abstract and Section II (Material Properties)"
    }
  ],
  "supply": [
    {
      "subject": "Rayon-based carbon precursor for the FiberForm preform",
      "producers": [],
      "critical_lists": [],
      "recycling": "Not found in any source we hold.",
      "substitutes": [
        "Lyocell-based PICA (PICA-D) is in development as a domestic replacement for rayon (Gasch et al. 2019)."
      ],
      "source": "gasch2019",
      "where": "Introduction, paragraphs on the supply chain issues and the PICA-D development plan. The rayon supply has been replaced at least twice in the past 25 years."
    },
    {
      "subject": "Rayon and Lyocell carbon-fibre precursors for PICA",
      "producers": [],
      "critical_lists": [],
      "recycling": "Not found in any source we hold.",
      "substitutes": [
        "Lyocell-based PICA (PICA-D) is the domestic replacement for rayon, with Lenzing as the precursor supplier (Ellerby et al. 2019)."
      ],
      "source": "ellerby2019",
      "where": "Challenges with PICA Sustainability table (slide 4) and the Lyocell supply slide"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "NASA Ames Thermal Protection Materials Database (TPSX): PICA [virgin], Material id 43",
      "type": "database",
      "url": "https://tpsx.arc.nasa.gov/Material?id=43",
      "year": 2006
    },
    {
      "title": "Ablation and Thermal Response Property Model Validation for Phenolic Impregnated Carbon Ablator (AIAA-2009-0262)",
      "type": "paper",
      "url": "https://ntrs.nasa.gov/api/citations/20110012891/downloads/20110012891.pdf",
      "year": 2009
    },
    {
      "title": "Development of Domestic Lyocell Based Phenolic Impregnated Carbon Ablator (PICA-D) for Future NASA Missions",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/20190031963/downloads/20190031963.pdf",
      "year": 2019
    },
    {
      "title": "Thermal Protection Materials Development, 1997-1998 Annual Report (NASA/CR 208331)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/19980235586/downloads/19980235586.pdf",
      "year": 1998
    },
    {
      "title": "Sustaining PICA TPS for Future NASA Robotic Science Missions (slides)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/20180006865/downloads/20180006865.pdf",
      "year": 2018
    },
    {
      "title": "Sustaining Phenolic Impregnated Carbon Ablator (PICA) for Future NASA Missions Including Discovery and New Frontiers (IPPW 2019 slides)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/20190028929/downloads/20190028929.pdf",
      "year": 2019
    },
    {
      "title": "PubChem compound summary, phenol (CID 996), GHS Classification",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/996"
    }
  ],
  "gaps": [
    "No flight-measured recession, surface temperature or in-flight data for PICA was found in the sources read; all recession and temperature values are arc-jet ground tests.",
    "The heat flux for each Milos and Chen (2009) Table 4 condition is not legible in the extracted text (Table 2 is garbled), so the recession rows give no heat flux.",
    "The Gasch et al. (2019) PICA-D tension, compression, shear, CTE and conductivity results are in figures only; no numbers were read from text, so none are listed.",
    "Virgin PICA gas permeability values in the 1998 report are garbled by OCR in the extracted text, so none are listed.",
    "No safety data sheet or PubChem GHS record for PICA itself was read in this run. The only hazard entry is for phenol, the monomer of phenolic resins, from PubChem; it is not the Durite SC-1008 resin used in PICA, and no SDS for that resin was read.",
    "The Ellerby et al. (2019) recession rows are arc-jet runs in air; the slide does not print the exposure time, so they are not a recession rate.",
    "No handling, storage or workplace guidance for PICA was read in this run.",
    "No humidity, UV, heat-ageing or radiation data for PICA was found in the sources read.",
    "No production share by country and no critical-mineral list status was found for the rayon precursor or FiberForm; the supply entry gives producers only by name.",
    "No licensed image was fetched, so the media list is empty.",
    "Eight sources are now read. The Stackpoole 2008 Stardust post-flight paper and the Tran 1994 and 1996 PICA papers were cited by the sources but not opened.",
    "The TPSX reference page (Reference id 74) returned HTTP 404, and a Wikipedia article for PICA does not exist, so neither was used.",
    "The NASA Stardust mission page does not mention PICA, and no value in this profile is taken from it. The NASA MSL page does not mention the heat shield.",
    "Orion candidate status comes from a 2009 paper; no current status was found.",
    "TPSX values read in this run but removed from properties: the value check cannot match the exponent notation the page prints, so they are kept here as printed. Density 2.36e+02 kg/m^3 (uncertainty 12.0, no unit printed); thermal conductivity 3.05e-01 W/m-K (labelled isotropic, temperature not printed; Milos and Chen 2009 call PICA strongly orthotropic); effective heat of ablation 1.15e+08 J/kg (uncertainty 5.77e+06, no unit printed; description ties it to heat fluxes of 300 to 1500 W/sqcm); pyrolysis gas enthalpy -9.02e+06 J/kg; tensile strength 1.34e+06 Pa in-plane and 2.41e+05 Pa through-thickness; tensile modulus 1.10e+08 Pa in-plane and 2.36e+07 Pa through-thickness; tensile strain to failure 1.20e-03 m/m in-plane and 8.50e-03 m/m through-thickness; volume fraction of resin 6.46e-02.",
    "Property names not in spores/property-canon.yaml and used here: emissivity, char_yield, centerline_recession and max_surface_temperature.",
    "The TPSX page prints no temperature for its specific heat and emissivity values."
  ],
  "story": {
    "why": "Phenolic Impregnated Carbon Ablator (PICA) is a low-density ablative heat shield developed at NASA Ames Research Center. The sources call it the lowest-density carbon-phenolic ablator with flight heritage (Gasch et al. 2019). It is made by infusing a rigid carbon-fibre preform with phenolic resin. Its density and ablation values come from NASA's TPSX database and from NASA papers, and this profile uses only the numbers printed in those sources.",
    "uses": [
      {
        "where": "Stardust (launched 1999)",
        "line": "PICA was the forebody heat shield of Stardust, the first sample-return mission from outside the Earth-Moon system. The TPSX database says Stardust was to re-enter at 16 Km/sec, and Gasch et al. describe the heat shield as a single cast piece."
      },
      {
        "where": "OSIRIS-REx",
        "line": "Gasch et al. report that OSIRIS-REx uses a single-piece PICA heat shield very similar to the Stardust design."
      },
      {
        "where": "Mars Science Laboratory and Mars 2020 (tiled)",
        "line": "PICA was used on Mars Science Laboratory in a tiled layout, and the Mars 2020 heat shield follows that layout (Gasch et al. 2019)."
      },
      {
        "where": "Orion Crew Module (candidate)",
        "line": "Milos and Chen (2009) call PICA a candidate heat shield material for the Orion Crew Module. The program tested newly manufactured PICA."
      }
    ],
    "can_do": [
      {
        "label": "Density",
        "line": "The 1998 NASA annual report gives a nominal density of 224 to 248 kg/m^3 for PICA, depending on the phenolic loading. The FiberForm substrate before impregnation is 144 to 176 kg/m^3 in the same report.",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Emissivity",
        "line": "TPSX lists an emissivity of 0.8 for virgin PICA. Its source column says measured, and the page gives no temperature for it.",
        "benchmark": "emissivity",
        "scope": "material",
        "value": "0.8"
      },
      {
        "label": "Specific heat",
        "line": "TPSX lists a specific heat of 1200 J/kg-K for virgin PICA. The page gives no temperature, and its source column says unknown.",
        "benchmark": "specific_heat",
        "scope": "material",
        "value": "1200 J/kg-K"
      },
      {
        "label": "Char",
        "line": "The phenolic resin in PICA leaves about 0.63 of its mass as char after pyrolysis at about 1250 K under argon (Selvaduray and Cox 1998). The report does not say whether 0.63 is a fraction or a percent.",
        "benchmark": "char_yield",
        "scope": "material"
      }
    ],
    "compare": "No other thermal-protection profile was read in this run, so this paragraph gives no side-by-side number. Within the sources read, PICA is described as the lowest-density carbon-phenolic ablator with flight heritage (Gasch et al. 2019). Its nominal density is 224 to 248 kg/m^3 and its arc-jet recession grows strongly with exposure time (2.33 mm at 55 s, 24.72 mm at 400 s, in different conditions). For a like-for-like table, read the other ablator profiles with the same method.",
    "compare_rows": [
      {
        "label": "Density, nominal PICA",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Specific heat, virgin PICA",
        "benchmark": "specific_heat",
        "scope": "material"
      },
      {
        "label": "Char yield of phenolic resin",
        "benchmark": "char_yield",
        "scope": "material"
      }
    ],
    "handling": [
      "Handle as a composite. The sources document only the test-model preparation: the exposed face was machined, and other faces were sealed or bonded.",
      "No storage or workplace handling guidance for PICA was read in this run.",
      "Plan for the precursor supply. The rayon source has been replaced at least twice in the past 25 years (Gasch et al. 2019)."
    ],
    "good_for": [
      "Entry heat shields that need a light carbon-phenolic ablator with flight heritage: Stardust, and Mars Science Laboratory in tiled form.",
      "Designs that need a NASA property set: TPSX gives density, specific heat, emissivity and effective heat of ablation for virgin PICA."
    ],
    "watch_out": [
      "Density depends on phenolic loading: 224 to 248 kg/m^3 nominal in the 1998 report.",
      "TPSX labels the conductivity isotropic, but Milos and Chen (2009) describe it as strongly orthotropic.",
      "Recession is large at long exposures: 24.72 mm after 400 s in one arc-jet condition.",
      "The rayon precursor supply has changed at least twice in the past 25 years, and the Lyocell replacement (PICA-D) is still in development."
    ],
    "verdict": "PICA is a flight-proven carbon-phenolic heat shield with NASA property values for virgin material. What the sources read here do not give is hazard data, ageing and humidity behaviour, in-flight measurements, or a settled precursor supply.",
    "recipe": {
      "line": "PICA is a composite of two parts: a rigid, low-density carbon-fibre preform (FiberForm) and a phenolic resin that fills the open space in the preform. The carbon fibres are made from rayon by a high-temperature conversion, and the preform is infused with phenolic resin and then cured (Gasch et al. 2019; Selvaduray and Cox 1998).",
      "parts": [
        {
          "name": "Carbon-fibre preform (FiberForm)",
          "symbol": "-",
          "role": "A rigid, porous carbon substrate made from chopped rayon-derived carbon fibres. It sets the low density and the open pore structure."
        },
        {
          "name": "Phenolic resin (Durite SC-1008)",
          "symbol": "-",
          "role": "Fills the void space between filaments. On heating it decomposes, and the char it leaves behind is what protects the surface."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "No safety data sheet or PubChem GHS entry for PICA itself was read, so this group has no verdict.",
        "points": [
          {
            "label": "Gap",
            "line": "The supplier safety data sheet and the PubChem record for PICA were not read in this run. The phenolic resin in PICA is a different product."
          }
        ],
        "level": 0,
        "verdict": "Not assessed in this run"
      },
      {
        "title": "If the heat shield ablates",
        "lead": "Ablation is the design mechanism: the surface material is removed in a controlled way. The sources give these values from arc-jet tests, not from flight.",
        "points": [
          {
            "label": "Recession at 55 s",
            "line": "In arc-jet test condition 1 of Milos and Chen (2009), a model recessed 2.33 mm in 55 s, with a maximum surface temperature of 2033 K. A second model under the same condition recessed 2.27 mm."
          },
          {
            "label": "Recession at 400 s",
            "line": "In arc-jet test condition 2b, a model recessed 24.72 mm in 400 s, with a maximum surface temperature of 2196 K. The heat flux for each condition is not legible in the extracted text."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "lead": "Only test-model preparation is documented in the sources read.",
        "points": [
          {
            "label": "Test models",
            "line": "In the arc-jet models, the exposed surface was machined, and the unexposed PICA surfaces were sealed or bonded to adjacent parts (Milos and Chen 2009)."
          }
        ]
      }
    ]
  },
  "updated": "2026-11-01",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 18,
    "unreachable": 1,
    "caveats": 2,
    "note": "Read by an AI assistant on 2026-11-01 from the TPSX page (raw HTML checked against the WebFetch summary) and three NASA PDFs (text-extracted with pdftotext). The value check could not match 11 TPSX values printed in exponent notation, so they are listed in gaps rather than in properties. One TPSX reference page returned 404 and was not used."
  },
  "sources": {
    "tpsx-pica": {
      "title": "NASA Ames Thermal Protection Materials Database (TPSX): PICA [virgin], Material id 43",
      "id": "TPSX Material id 43; manufacturer Fiber Materials Inc.; point of contact F.S. Milos",
      "url": "https://tpsx.arc.nasa.gov/Material?id=43",
      "year": 2006,
      "kind": "database",
      "license": "NASA public database (cited, not reproduced)"
    },
    "milos2009": {
      "title": "Ablation and Thermal Response Property Model Validation for Phenolic Impregnated Carbon Ablator",
      "id": "AIAA-2009-0262 (47th AIAA Aerospace Sciences Meeting); NTRS 20110012891; F.S. Milos and Y.-K. Chen, NASA Ames",
      "url": "https://ntrs.nasa.gov/api/citations/20110012891/downloads/20110012891.pdf",
      "year": 2009,
      "kind": "paper",
      "license": "NASA NTRS public record (cited, not reproduced)"
    },
    "gasch2019": {
      "title": "Development of Domestic Lyocell Based Phenolic Impregnated Carbon Ablator (PICA-D) for Future NASA Missions",
      "id": "NTRS 20190031963; M. Gasch et al., NASA Ames and Fiber Materials Inc.",
      "url": "https://ntrs.nasa.gov/api/citations/20190031963/downloads/20190031963.pdf",
      "year": 2019,
      "kind": "report",
      "license": "NASA NTRS public record (cited, not reproduced)"
    },
    "selvaduray1998": {
      "title": "Thermal Protection Materials Development, 1997-1998 Annual Report",
      "id": "NASA/CR 208331; NTRS 19980235586; G. Selvaduray and M. Cox, San Jose State University",
      "url": "https://ntrs.nasa.gov/api/citations/19980235586/downloads/19980235586.pdf",
      "year": 1998,
      "kind": "report",
      "license": "NASA NTRS public record (cited, not reproduced)"
    },
    "nasa-stardust": {
      "title": "NASA Science: Stardust mission page",
      "id": "science.nasa.gov/mission/stardust",
      "url": "https://science.nasa.gov/mission/stardust/",
      "year": 2026,
      "kind": "web",
      "license": "NASA web page (cited, not reproduced)"
    },
    "stackpoole2018": {
      "title": "Sustaining PICA TPS for Future NASA Robotic Science Missions (slides)",
      "id": "NTRS 20180006865; M. Stackpoole, E. Venkatapathy and M. Gasch, NASA Ames; S. Violette, Fiber Materials Inc.",
      "url": "https://ntrs.nasa.gov/api/citations/20180006865/downloads/20180006865.pdf",
      "year": 2018,
      "kind": "report",
      "license": "NASA NTRS public record (cited, not reproduced)"
    },
    "ellerby2019": {
      "title": "Sustaining Phenolic Impregnated Carbon Ablator (PICA) for Future NASA Missions Including Discovery and New Frontiers",
      "id": "NTRS 20190028929; International Planetary Probe Workshop, 2019; D. Ellerby et al., NASA Ames",
      "url": "https://ntrs.nasa.gov/api/citations/20190028929/downloads/20190028929.pdf",
      "year": 2019,
      "kind": "report",
      "license": "NASA NTRS public record (cited, not reproduced)"
    },
    "pubchem-phenol": {
      "title": "PubChem compound summary, phenol (CID 996), GHS Classification",
      "id": "PubChem CID 996",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/996",
      "kind": "database",
      "license": "PubChem public record (cited, not reproduced)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/pica/"
}