{ "spore": "profile", "id": "multilayer-insulation-mli", "spore_version": "0.2", "family": "multilayer-insulation", "name": "Multilayer insulation (MLI) blanket, aluminized Mylar and Kapton", "abbreviation": "MLI", "role": "flexible reflective thermal blanket for spacecraft and cryogenic tanks", "category": "thermal-protection", "type": "multi-layer-insulation", "summary": "Multilayer insulation (MLI) is a stack of thin polymer films, each coated with vacuum-deposited aluminium, separated by spacer netting or scrim. NASA's MLI guideline gives an infrared emittance of 0.05 maximum and 0.03 typical for double-aluminized Mylar reflector layers (NASA TP-1999-209263, Table 2). A Lockheed study for NASA measured a total hemispherical emittance of 0.028 at 300 K for double-aluminized 1/4-mil Mylar (NASA CR-72605, Table 5-1). In a NASA Technical Memorandum, an aluminized polyimide (Kapton) MLI reached a backface temperature of 110 °C at 15 min at 1.5 mm Hg, against 145 °C for an AFRSI of equivalent thickness and density.\n", "best_for": "Radiative thermal insulation in vacuum on spacecraft exteriors and cryogenic tanks, where low emittance and low mass per area matter (NASA guideline and tests)", "weakest_at": "Exposed surfaces in low Earth orbit: atomic oxygen erodes most organic films, long-term UV changes their optical and mechanical properties, and plasma charging can cause static discharge (NASA TP-1999-209263, Sections 6.1, 6.2 and 6.6)", "identity": { "formula": "Aluminized polyester (Mylar, PET) or aluminized polyimide (Kapton) film layers, separated by polyester or aramid-free spacer netting or ceramic scrim", "designations": [], "source": "finckenor1999", "where": "Section 4.1 and Table 2 (reflector layers); Table 3 (separator netting); Kourtides Table 1 (film spacer and aluminum shield)" }, "tags": { "environments": [ "low-earth-orbit" ], "stresses": [ "atomic-oxygen", "uv", "extreme-heat", "extreme-cold", "micrometeoroids-and-debris", "vacuum-and-outgassing" ], "applications": [ "thermal-control", "heat-shields", "cryogenic-fuel" ] }, "properties": [ { "benchmark": "infrared_emittance", "label": "Infrared emittance, maximum, double-aluminized Mylar reflector layer", "value": 0.05, "bound": "exact", "unit": "-", "scope": "material", "conditions": { "film": "double-aluminized Mylar reflector layer", "basis": "maximum value in Table 2", "note_on_footnote": "Footnote [3] points to a separate table of single-aluminized Mylar values; those values are not used here" }, "method": "Value printed in a NASA material guideline table", "status": "ground", "source": "finckenor1999", "where": "Section 4.1, Table 2 (Reflector layers), Aluminized Mylar column, Infrared emittance e (max/typ)", "source_detail": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" } }, { "benchmark": "infrared_emittance", "label": "Infrared emittance, typical, double-aluminized Mylar reflector layer", "value": 0.03, "bound": "exact", "unit": "-", "scope": "material", "conditions": { "film": "double-aluminized Mylar reflector layer", "basis": "typical value in Table 2", "note_on_footnote": "Footnote [3] points to a separate table of single-aluminized Mylar values; those values are not used here" }, "method": "Value printed in a NASA material guideline table", "status": "ground", "source": "finckenor1999", "where": "Section 4.1, Table 2 (Reflector layers), Aluminized Mylar column, Infrared emittance e (max/typ)", "source_detail": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" } }, { "benchmark": "solar_absorptance", "label": "Solar absorptance, maximum, double-aluminized Mylar reflector layer", "value": 0.14, "bound": "exact", "unit": "-", "scope": "material", "conditions": { "film": "double-aluminized Mylar reflector layer", "basis": "maximum value in Table 2" }, "method": "Value printed in a NASA material guideline table", "status": "ground", "source": "finckenor1999", "where": "Section 4.1, Table 2 (Reflector layers), Aluminized Mylar column, Absorptance a (max/typ)", "source_detail": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" } }, { "benchmark": "solar_absorptance", "label": "Solar absorptance, typical, double-aluminized Mylar reflector layer", "value": 0.12, "bound": "exact", "unit": "-", "scope": "material", "conditions": { "film": "double-aluminized Mylar reflector layer", "basis": "typical value in Table 2" }, "method": "Value printed in a NASA material guideline table", "status": "ground", "source": "finckenor1999", "where": "Section 4.1, Table 2 (Reflector layers), Aluminized Mylar column, Absorptance a (max/typ)", "source_detail": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" } }, { "benchmark": "infrared_emittance", "label": "Total hemispherical emittance, double-aluminized 1/4-mil Mylar at 540 R (300 K)", "value": 0.028, "bound": "exact", "unit": "-", "scope": "material", "conditions": { "film": "double-aluminized 1/4-mil Mylar reflective shield", "temperature": "540 R (300 K)", "measurement": "total hemispherical emittance" }, "method": "Summary table of measured emittance values in a Lockheed interim report for NASA", "status": "ground", "source": "cunnington1971", "where": "Section 5, Table 5-1 (Summary of total hemispherical emittance data for 1/4-mil Mylar reflective shields), Double-Aluminized Mylar row", "source_detail": { "title": "NASA CR-72605 (LMSC-A903316): Thermal Performance of Multilayer Insulations, interim report", "id": "NASA CR-72605; Lockheed Missiles and Space Company, contract NAS3-12025", "url": "https://ntrs.nasa.gov/citations/19710014824", "year": 1971, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "infrared_emittance", "label": "Total hemispherical emittance, double-aluminized 1/4-mil Mylar at 300 R (167 K)", "value": 0.018, "bound": "exact", "unit": "-", "scope": "material", "conditions": { "film": "double-aluminized 1/4-mil Mylar reflective shield", "temperature": "300 R (167 K)", "measurement": "total hemispherical emittance" }, "method": "Summary table of measured emittance values in a Lockheed interim report for NASA", "status": "ground", "source": "cunnington1971", "where": "Section 5, Table 5-1 (Summary of total hemispherical emittance data for 1/4-mil Mylar reflective shields), Double-Aluminized Mylar row", "source_detail": { "title": "NASA CR-72605 (LMSC-A903316): Thermal Performance of Multilayer Insulations, interim report", "id": "NASA CR-72605; Lockheed Missiles and Space Company, contract NAS3-12025", "url": "https://ntrs.nasa.gov/citations/19710014824", "year": 1971, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "infrared_emittance", "label": "Total hemispherical emittance, double-aluminized 1/4-mil Mylar at 115 R (64 K)", "value": 0.01, "bound": "exact", "unit": "-", "scope": "material", "conditions": { "film": "double-aluminized 1/4-mil Mylar reflective shield", "temperature": "115 R (64 K)", "measurement": "total hemispherical emittance" }, "method": "Summary table of measured emittance values in a Lockheed interim report for NASA", "status": "ground", "source": "cunnington1971", "where": "Section 5, Table 5-1 (Summary of total hemispherical emittance data for 1/4-mil Mylar reflective shields), Double-Aluminized Mylar row", "source_detail": { "title": "NASA CR-72605 (LMSC-A903316): Thermal Performance of Multilayer Insulations, interim report", "id": "NASA CR-72605; Lockheed Missiles and Space Company, contract NAS3-12025", "url": "https://ntrs.nasa.gov/citations/19710014824", "year": 1971, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "areal_density", "label": "Areal weight, aluminized Mylar, 0.025 mm (1.0 mil) film", "value": 0.0033, "bound": "exact", "unit": "gm/cm2", "scope": "material", "conditions": { "film": "aluminized Mylar reflector layer", "thickness": "0.025 mm (1.0 mil)", "printed_alternate_unit": "0.060 oz/yd2" }, "method": "Value printed in a NASA material guideline table", "status": "ground", "source": "finckenor1999", "where": "Section 4.1, Table 2 (Reflector layers), Weight row for 0.025 mm (1.0 mil), Aluminized Mylar column", "source_detail": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" } }, { "benchmark": "areal_density", "label": "Areal weight, aluminized Mylar, 0.051 mm (2.0 mil) film", "value": 0.0066, "bound": "exact", "unit": "gm/cm2", "scope": "material", "conditions": { "film": "aluminized Mylar reflector layer", "thickness": "0.051 mm (2.0 mil)", "printed_alternate_unit": "0.12 oz/yd2" }, "method": "Value printed in a NASA material guideline table", "status": "ground", "source": "finckenor1999", "where": "Section 4.1, Table 2 (Reflector layers), Weight row for 0.051 mm (2.0 mil), Aluminized Mylar column", "source_detail": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" } }, { "benchmark": "areal_density", "label": "Areal weight, aluminized Mylar, 0.076 mm (3.0 mil) film", "value": 0.0104, "bound": "exact", "unit": "gm/cm2", "scope": "material", "conditions": { "film": "aluminized Mylar reflector layer", "thickness": "0.076 mm (3.0 mil)", "printed_alternate_unit": "0.19 oz/yd2" }, "method": "Value printed in a NASA material guideline table", "status": "ground", "source": "finckenor1999", "where": "Section 4.1, Table 2 (Reflector layers), Weight row for 0.076 mm (3.0 mil), Aluminized Mylar column", "source_detail": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" } }, { "benchmark": "areal_density", "label": "Areal weight, aluminized polyimide (Kapton) film", "value": 18, "bound": "exact", "unit": "g/m2", "scope": "material", "conditions": { "film": "polyimide film 0.0012 cm thick with about 700 Å chemically vapor-deposited aluminum", "qualifier": "printed as approximately" }, "method": "Value stated in the text of a NASA Technical Memorandum", "status": "ground", "source": "kourtides1989", "where": "Section 3 (Description of materials), paragraph on the aluminized film weight", "source_detail": { "title": "NASA TM-101071: Composite Multilayer Insulations for Thermal Protection of Aerospace Vehicles", "id": "NASA TM-101071 (Ames Research Center)", "url": "https://ntrs.nasa.gov/citations/19900000867", "year": 1989, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "max_service_temp", "label": "Continuous maximum temperature, aluminized Mylar", "value": 93, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "film": "aluminized Mylar reflector layer", "basis": "continuous, max/min as printed", "footnote": "Footnote [1] says the range for double-aluminized Mylar may be limited to 120 °C depending on the blanket's sensitivity to shrinkage" }, "method": "Value printed in a NASA material guideline table", "status": "ground", "source": "finckenor1999", "where": "Section 4.1, Table 2 (Reflector layers), Temperature row, Continuous max/min, Aluminized Mylar column", "source_detail": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" } }, { "benchmark": "min_service_temp", "label": "Continuous minimum temperature, aluminized Mylar", "value": -250, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "film": "aluminized Mylar reflector layer", "basis": "continuous, max/min as printed" }, "method": "Value printed in a NASA material guideline table", "status": "ground", "source": "finckenor1999", "where": "Section 4.1, Table 2 (Reflector layers), Temperature row, Continuous max/min, Aluminized Mylar column", "source_detail": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" } }, { "benchmark": "max_service_temp", "label": "Continuous maximum temperature, aluminized Kapton", "value": 288, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "film": "aluminized Kapton reflector layer", "basis": "continuous, max/min as printed" }, "method": "Value printed in a NASA material guideline table", "status": "ground", "source": "finckenor1999", "where": "Section 4.1, Table 2 (Reflector layers), Temperature row, Continuous max/min, Aluminized Kapton column", "source_detail": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" } }, { "benchmark": "oxidative_degradation_onset", "label": "Onset of oxidative degradation, aluminized polyimide film", "value": 500, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "film": "aluminized polyimide (Kapton) film", "atmosphere": "air, thermogravimetric analysis", "qualifier": "printed as approximately" }, "method": "Thermogravimetric analysis reported in a NASA Technical Memorandum", "status": "ground", "source": "kourtides1989", "where": "Section 3 (Description of materials), paragraph on the thermogravimetric analysis (Figure 12)", "source_detail": { "title": "NASA TM-101071: Composite Multilayer Insulations for Thermal Protection of Aerospace Vehicles", "id": "NASA TM-101071 (Ames Research Center)", "url": "https://ntrs.nasa.gov/citations/19900000867", "year": 1989, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "backface_temperature", "label": "Backface temperature after 15 min, composite MLI with aluminized polyimide film and silica insulation", "value": 110, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "insulation": "aluminized polyimide film spacer, silica felt, 2.4 cm thick", "pressure": "1.5 mm Hg", "time": "15 min", "top_surface": "heated to about 1070 °C for 2 min, then cooled" }, "method": "Measured heat-pulse test reported in a NASA Technical Memorandum", "status": "ground", "source": "kourtides1989", "where": "Section 6 (Conclusions), item 2; Section 4 (Test results)", "source_detail": { "title": "NASA TM-101071: Composite Multilayer Insulations for Thermal Protection of Aerospace Vehicles", "id": "NASA TM-101071 (Ames Research Center)", "url": "https://ntrs.nasa.gov/citations/19900000867", "year": 1989, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "backface_temperature", "label": "Backface temperature after 15 min, AFRSI reference of equivalent thickness and density", "value": 145, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "insulation": "AFRSI, silica felt, 2.4 cm thick", "pressure": "1.5 mm Hg", "time": "15 min", "note": "The source states equivalent thickness and density to the composite MLI tested" }, "method": "Measured heat-pulse test reported in a NASA Technical Memorandum", "status": "ground", "source": "kourtides1989", "where": "Section 6 (Conclusions), item 2", "source_detail": { "title": "NASA TM-101071: Composite Multilayer Insulations for Thermal Protection of Aerospace Vehicles", "id": "NASA TM-101071 (Ames Research Center)", "url": "https://ntrs.nasa.gov/citations/19900000867", "year": 1989, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "density", "label": "Density, unmetallized Kapton HN polyimide film", "value": 1.42, "bound": "exact", "unit": "g/cc", "scope": "material", "conditions": { "film": "unmetallized DuPont Kapton HN polyimide film (base film, not the aluminized reflector)", "temperature": "23 degC (73 degF)", "test": "ASTM D-1505-90" }, "method": "Typical value printed in a DuPont datasheet (copy hosted on epectec.com)", "status": "ground", "source": "dupont-kapton-hn", "where": "Table 1 (Physical Properties of DuPont Kapton HN at 23 degC), row Density", "source_detail": { "title": "DuPont Kapton HN polyimide film: technical datasheet (copy hosted on epectec.com)", "id": "DuPont Kapton HN datasheet, copyright 2016 DuPont (cites H-38479 and Bulletin GS-96-7)", "url": "https://www.epectec.com/downloads/DuPont-Kapton-HN-Polyimide-Film.pdf", "year": 2016, "kind": "datasheet", "license": "DuPont copyright, cited not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Ultimate tensile strength, unmetallized Kapton HN polyimide film at 23 degC", "value": 231, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "film": "unmetallized DuPont Kapton HN polyimide film (base film, not aluminized)", "temperature": "23 degC (73 degF)", "test": "ASTM D-882-91, Method A", "printed_alternate": "33,500 psi", "gauges": "the 25, 50, 75 and 125 micrometre columns of Table 1 print the same value" }, "method": "Typical value printed in a DuPont datasheet (copy hosted on epectec.com)", "status": "ground", "source": "dupont-kapton-hn", "where": "Table 1 (Physical Properties), row Ultimate Tensile Strength at 23 degC", "source_detail": { "title": "DuPont Kapton HN polyimide film: technical datasheet (copy hosted on epectec.com)", "id": "DuPont Kapton HN datasheet, copyright 2016 DuPont (cites H-38479 and Bulletin GS-96-7)", "url": "https://www.epectec.com/downloads/DuPont-Kapton-HN-Polyimide-Film.pdf", "year": 2016, "kind": "datasheet", "license": "DuPont copyright, cited not reproduced" } }, { "benchmark": "cte", "label": "Coefficient of linear expansion, unmetallized Kapton HN polyimide film", "value": 20, "bound": "exact", "unit": "ppm/°C", "scope": "material", "conditions": { "film": "unmetallized DuPont Kapton HN polyimide film (base film, not aluminized)", "temperature_range": "-14 to 38 degC (7 to 100 degF)", "test": "ASTM D-696-91", "printed_alternate": "11 ppm/°F" }, "method": "Typical value printed in a DuPont datasheet (copy hosted on epectec.com)", "status": "ground", "source": "dupont-kapton-hn", "where": "Table 2 (Thermal Properties), row Thermal Coefficient of Linear Expansion", "source_detail": { "title": "DuPont Kapton HN polyimide film: technical datasheet (copy hosted on epectec.com)", "id": "DuPont Kapton HN datasheet, copyright 2016 DuPont (cites H-38479 and Bulletin GS-96-7)", "url": "https://www.epectec.com/downloads/DuPont-Kapton-HN-Polyimide-Film.pdf", "year": 2016, "kind": "datasheet", "license": "DuPont copyright, cited not reproduced" } }, { "benchmark": "specific_heat", "label": "Specific heat, unmetallized Kapton HN polyimide film", "value": 1.09, "bound": "exact", "unit": "J/g•K", "scope": "material", "conditions": { "film": "unmetallized DuPont Kapton HN polyimide film (base film, not aluminized)", "temperature": "not printed in the datasheet", "printed_alternate": "0.261 cal/g·°C" }, "method": "Typical value printed in a DuPont datasheet (copy hosted on epectec.com); method printed as differential calorimetry", "status": "ground", "source": "dupont-kapton-hn", "where": "Table 2 (Thermal Properties), row Specific Heat", "source_detail": { "title": "DuPont Kapton HN polyimide film: technical datasheet (copy hosted on epectec.com)", "id": "DuPont Kapton HN datasheet, copyright 2016 DuPont (cites H-38479 and Bulletin GS-96-7)", "url": "https://www.epectec.com/downloads/DuPont-Kapton-HN-Polyimide-Film.pdf", "year": 2016, "kind": "datasheet", "license": "DuPont copyright, cited not reproduced" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity, unmetallized Kapton HN polyimide film", "value": 0.12, "bound": "exact", "unit": "W/m•K", "scope": "material", "conditions": { "film": "unmetallized DuPont Kapton HN polyimide film (base film, not aluminized)", "temperature": "296 K", "test": "ASTM F-433-77 (1987)" }, "method": "Typical value printed in a DuPont datasheet (copy hosted on epectec.com)", "status": "ground", "source": "dupont-kapton-hn", "where": "Table 2 (Thermal Properties), row Coefficient of Thermal Conductivity, W/m•K, value at 296K", "source_detail": { "title": "DuPont Kapton HN polyimide film: technical datasheet (copy hosted on epectec.com)", "id": "DuPont Kapton HN datasheet, copyright 2016 DuPont (cites H-38479 and Bulletin GS-96-7)", "url": "https://www.epectec.com/downloads/DuPont-Kapton-HN-Polyimide-Film.pdf", "year": 2016, "kind": "datasheet", "license": "DuPont copyright, cited not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Tensile strength (MD), Mylar A polyester film, 48 gauge, base film", "value": 26, "bound": "exact", "unit": "kpsi", "scope": "material", "conditions": { "film": "Mylar A polyester (PET) film, 48 gauge, machine direction (base film, not aluminized)", "test": "ASTM D882A", "printed_alternate": "none; the datasheet prints kpsi only, not MPa" }, "method": "Typical value printed in a Mylar Specialty Films technical datasheet", "status": "ground", "source": "mylar-a-datasheet", "where": "Typical Properties, PHYSICAL, row Tensile Strength MD, 48 gauge", "source_detail": { "title": "Mylar A polyester film: technical datasheet, US customary units (Mylar Specialty Films)", "id": "Mylar Specialty Films, Mylar A datasheet, copyright 2024", "url": "https://mylar.com/wp-content/uploads/2025/08/mylar_a-1.pdf", "year": 2024, "kind": "datasheet", "license": "Mylar Specialty Films copyright, cited not reproduced" } } ], "corrosion": [ { "environment": "Atomic oxygen in low Earth orbit", "headline": "Atomic oxygen erodes most organic films, so exposed MLI surfaces must be made of AO-resistant materials.", "effect": "NASA states that AO erodes most organic materials and will react with a number of metals and other inorganic materials. MLI blanket surfaces exposed to AO shall be made of AO-resistant materials that will maintain the thermal design requirements for the life of the blanket. Figure 7 of the same guideline shows AO erosion of Kapton and silvered Teflon samples flown on LDEF.", "rating": "severe", "conditions": { "exposure": "low Earth orbit, atomic oxygen flux", "film": "Kapton and Teflon samples shown in Figure 7 (LDEF)" }, "source": "finckenor1999", "where": "Section 6.1 (Atomic Oxygen) and Figure 7" }, { "environment": "Atomic oxygen erosion of polyimide (Kapton) films in low Earth orbit", "headline": "NASA Glenn describes atomic oxygen erosion of polyimide Kapton as a threat to spacecraft performance and durability.", "effect": "NASA Glenn states that atomic oxygen reaction with polymers causes erosion, which is a threat to spacecraft performance and durability, and names Kapton (DuPont) polyimide as a commonly used spacecraft polymer. The paper describes an in-situ optical method for measuring erosion yield. It gives no erosion yield value for Kapton and no severity rating.", "rating": "unknown", "conditions": { "basis": "qualitative statement in a NASA Glenn technical paper on an optical erosion-measurement technique; no numeric erosion yield for Kapton in the text read", "material": "polyimide Kapton (DuPont)" }, "source": "nasa-ao-optical", "where": "Introduction (first two paragraphs)" }, { "environment": "Ultraviolet radiation in space", "headline": "Long-term UV changes the optical and mechanical properties of MLI materials.", "effect": "NASA states that long-term exposure to UV radiation has been shown to cause significant changes in optical and mechanical properties for various materials, and that materials exposed to UV shall not embrittle or show significant change in optical or mechanical properties for the life of the material. UV combined with AO can cause reactions that might not take place with AO or UV alone.", "rating": "moderate", "conditions": { "exposure": "long-term space UV, with or without atomic oxygen", "film": "general requirement for MLI materials, not a film-specific test" }, "source": "finckenor1999", "where": "Section 6.2 (Ultraviolet Radiation)" }, { "environment": "Heating in air during cleaning, and thermal oxidation above 500 °C", "headline": "Aluminized polyimide film survived 454 °C heat cleaning in air, and its oxidative degradation starts near 500 °C.", "effect": "The Kourtides test film showed no degradation during heat cleaning at 454 °C in air for 2 hr, but was slightly curled by the thermal-expansion mismatch between aluminum and polyimide. Thermogravimetric analysis showed oxidative degradation of the film starting at about 500 °C. The reflectance of the aluminum, whether as foil or vapor-deposited on polyimide, did not degrade significantly with temperature.", "rating": "low", "conditions": { "atmosphere": "air, heat cleaning 2 hr at 454 °C", "film": "0.0012 cm polyimide with about 700 Å CVD aluminum" }, "source": "kourtides1989", "where": "Section 3 (Description of materials), paragraphs on heat cleaning and thermogravimetric analysis; Section 6 (Conclusions), item 3" }, { "environment": "Humid storage or handling", "headline": "No humidity or water-uptake result was found in the three NASA sources.", "effect": "The sources read for this profile do not give a humidity exposure test, a water-uptake value or a hydrolysis result for the Mylar or Kapton films. This entry is recorded so the gap is visible.", "rating": "low", "conditions": { "basis": "absence of data in the sources read" }, "source": "finckenor1999", "where": "Not found in the sections read" } ], "risks": { "hazards": [ { "text": "PubChem's aggregated GHS record for aluminum metal (CID 5359268) lists H228 Flammable solid for 60.6% of company reports, H250 Catches fire spontaneously if exposed to air for 34.2%, and H261 In contact with water releases flammable gas for 90.8%, all with the signal word Danger. The same record says 338 of 4079 company reports (8.3%) do not meet GHS hazard criteria. The record does not state the physical form of aluminum for these reports, so these classes are not a finding for the vacuum-deposited film.", "ghs": [ "H228", "H250", "H261" ], "source": "pubchem-aluminum", "where": "Safety and Hazards, GHS Classification, aggregated notifications (CID 5359268)" } ], "failure_risks": [ { "mode": "Atomic oxygen erosion of exposed blanket surfaces", "trigger": "Exposure to atomic oxygen in low Earth orbit", "consequence": "Erosion of organic surfaces; the guideline requires AO-resistant outer materials so the blanket keeps its thermal design for life", "severity": "high", "source": "finckenor1999", "where": "Section 6.1 (Atomic Oxygen)" }, { "mode": "Tearing of the blanket by ground-support airflow", "trigger": "Launch-vehicle nose shroud cooling fans set too high", "consequence": "The air flow pulled and ripped the MLI. In late 1997 the Huygens probe on the Cassini spacecraft had to be removed for repairs to the MLI covering its heat shield.", "severity": "moderate", "source": "finckenor1999", "where": "Section 7 (ground handling text before Section 7.8)" }, { "mode": "Electrostatic discharge from plasma charging", "trigger": "Plasma in low Earth orbit (below about 5,000 km) charging surfaces that are not well connected", "consequence": "Static electric discharge between the spacecraft and the plasma, or between partly insulated elements, can cause severe damage to key electrical components", "severity": "high", "source": "finckenor1999", "where": "Section 6.6 (Plasma Effects)" }, { "mode": "Shrinkage of the double-aluminized Mylar blanket", "trigger": "Use above the limit in Table 2, footnote [1], where the blanket is sensitive to shrinkage", "consequence": "The temperature range for double-aluminized Mylar may be limited to 120 °C (250 °F); the guideline advises shrinking the blanket before installation", "severity": "moderate", "source": "finckenor1999", "where": "Section 4.1, Table 2, footnote [1]" }, { "mode": "Melting of Dacron separator netting", "trigger": "Exposure above 177 °C (350 °F)", "consequence": "Dacron netting may shrink and melt above 177 °C (350 °F)", "severity": "moderate", "source": "finckenor1999", "where": "Section 4.1.3, Table 3 (Separator layers), footnote 1" }, { "mode": "Curling of the aluminized polyimide film after heating", "trigger": "Heat cleaning at 454 °C in air, from the thermal-expansion mismatch between aluminum and polyimide", "consequence": "The film was slightly curled; the source judges this not a severe problem because the blankets are sewn in a quilted configuration", "severity": "low", "source": "kourtides1989", "where": "Section 3 (Description of materials), paragraph on heat cleaning" } ], "side_effects": [], "handling": [ { "text": "Finckenor says materials that do not meet outgassing requirements shall undergo a component bakeout before assembly, to MSFC-SPEC-1238.", "source": "finckenor1999", "where": "Section 6.5 (Outgassing)" }, { "text": "MLI blankets must be tested for flammability, and the guideline limits the use of hook-and-pile fasteners to a total area on each blanket.", "source": "finckenor1999", "where": "Requirements section, text on flammability testing and Section 4.5.1 (hook-and-pile fasteners)" }, { "text": "Shrink the blanket before installation, as the guideline advises for double-aluminized Mylar.", "source": "finckenor1999", "where": "Section 4.1, Table 2, footnote [1]" } ], "mitigations": [ { "text": "Electrical grounding straps ground the MLI layers to the primary structure. Blankets smaller than 1 m2 may not need grounding; blankets over 1 m2 need at least two grounds.", "source": "finckenor1999", "where": "Section 7.1 (Electrical Bonding and Grounding) and Figure 10" }, { "text": "Conductive tape can ground the layers; the guideline notes that conductive properties matter more than optical properties for this tape.", "source": "finckenor1999", "where": "Section 4.4.4 (Conductive Tape)" }, { "text": "Outer covers that are not opaque to UV carry a metallized reflector layer under them as a light block.", "source": "finckenor1999", "where": "Section 4.1.1 (Outer Cover)" } ] }, "uses": [ { "application": "thermal-control", "device": "Spacecraft exterior blankets", "example": "Finckenor states that MLI protects spacecraft exteriors and also insulates cryogenic fluids for long periods.", "source": "finckenor1999", "where": "Section 7.8 (Cryogenic Insulation)" }, { "application": "cryogenic-fuel", "device": "Liquid hydrogen tank insulation (analysed, with a vacuum test)", "example": "Lockheed tested double-aluminized 1/4-mil Mylar with double silk net spacers on a cryogen tank in vacuum, and compared insulation and propellant boiloff weight for 30 days of liquid hydrogen storage in a space environment.", "source": "cunnington1971", "where": "Summary section and Section 5" }, { "application": "heat-shields", "device": "Heat shield covering on the Huygens probe (Cassini)", "example": "In late 1997 the Huygens probe on the Cassini spacecraft had to be removed for repairs to the MLI covering the heat shield, after launch-vehicle fans pulled and ripped the blanket.", "source": "finckenor1999", "where": "Section 7 (ground handling text before Section 7.8)" }, { "application": "heat-shields", "device": "Experimental aerobrake thermal protection for an aeroassisted orbital transfer vehicle (AOTV)", "example": "Kourtides and Pitts describe a composite insulation with aluminized polyimide film as an experimental TPS on the aerobrake of the AOTV, which they expected to have lower thermal conductivity than the baseline AFRSI.", "source": "kourtides1989", "where": "Section 5 (Data analysis), final paragraph" } ], "supply": [ { "subject": "Aluminium (vacuum-deposited reflector coating)", "producers": [ { "country": "China", "share_percent": 60.8, "year": 2025 }, { "country": "India", "share_percent": 5.7, "year": 2025 }, { "country": "Russia", "share_percent": 5.3, "year": 2025 }, { "country": "Canada", "share_percent": 4.5, "year": 2025 }, { "country": "United Arab Emirates", "share_percent": 3.6, "year": 2025 } ], "critical_lists": [], "recycling": "USGS: in 2025, aluminum recovered from purchased scrap in the United States was about 3.6 million tons.", "substitutes": [], "source": "usgs-mcs2026-aluminum", "where": "World Smelter Production and Capacity table, 2025e (world total 74,000 thousand t); shares calculated by Space Mushroom from the country values; Recycling paragraph" } ], "media": [], "documents": [ { "title": "NASA TP-1999-209263: Multilayer Insulation Material Guidelines (Finckenor and Dooling, MSFC)", "type": "report", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999 }, { "title": "NASA CR-72605 (LMSC-A903316): Thermal Performance of Multilayer Insulations (Cunnington, Keller and Bell, Lockheed Missiles and Space Company)", "type": "report", "url": "https://ntrs.nasa.gov/citations/19710014824", "year": 1971 }, { "title": "NASA TM-101071: Composite Multilayer Insulations for Thermal Protection of Aerospace Vehicles (Kourtides and Pitts)", "type": "report", "url": "https://ntrs.nasa.gov/citations/19900000867", "year": 1989 }, { "title": "USGS Mineral Commodity Summaries 2026: Aluminum", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf", "year": 2026 }, { "title": "PubChem compound record: Aluminum (CID 5359268), GHS classification summary", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5359268", "year": 2026 }, { "title": "DuPont Kapton HN polyimide film technical datasheet (copy hosted on epectec.com)", "type": "datasheet", "url": "https://www.epectec.com/downloads/DuPont-Kapton-HN-Polyimide-Film.pdf", "year": 2016 }, { "title": "Mylar A polyester film technical datasheet (Mylar Specialty Films)", "type": "datasheet", "url": "https://mylar.com/wp-content/uploads/2025/08/mylar_a-1.pdf", "year": 2024 }, { "title": "NASA NTRS 20050214723: New Active Optical Technique Developed for Measuring LEO Atomic Oxygen Erosion of Polymers", "type": "report", "url": "https://ntrs.nasa.gov/citations/20050214723", "year": 2005 } ], "gaps": [ "Density of the Mylar A (PET) film is not printed in the Mylar A datasheet, and no MPa tensile value was read for it (the datasheet prints kpsi). Moisture uptake and elongation were not read for either film.", "The Kapton HN density, strength, expansion, specific heat and conductivity above are for the unmetallized base film. No datasheet value for the aluminized Kapton film itself was read.", "No film hazard data: no safety data sheet or PubChem GHS record was read for the Mylar or Kapton films or the netting. The only hazard entry is PubChem's aggregate for aluminum metal, which does not state a form. Finckenor's flammability requirement is listed under handling instead.", "No in-orbit measurement of emittance or solar absorptance for these films was found. The values are from ground tests and handbook tables.", "No humidity exposure, water uptake or hydrolysis data for Mylar or Kapton were found in the sources read.", "Supply of the polymer films (PET, polyimide) is not covered: no producer share was read for them.", "Aluminium crustal abundance and critical-mineral status were not stated in the USGS aluminum summary read for this profile, so critical_lists is left out.", "Density of the Kourtides composite MLI (0.13 in Table 1, 2.4 cm thick) is left out: the unit printed in that table could not be confirmed against the page.", "Intermittent temperature limits (150 °C for aluminized Mylar, 400 °C for aluminized Kapton) and the grounding resistance limits in Section 7.1 are left out: the text extraction of those values was unclear.", "Property names not in the canonical list: infrared_emittance, solar_absorptance, areal_density, oxidative_degradation_onset and backface_temperature. They are snake_case names chosen for this profile.", "No product designation was read for this grade. The MDAC-STM0691 specification printed in Table 2 is a specification, not a designation, so identity.designations is left out." ], "story": { "why": "Multilayer insulation (MLI) is a flexible blanket of thin metallized films that limits radiant heat transfer in vacuum. NASA describes its use as protection for spacecraft exteriors and as insulation for cryogenic fluids. Long-term low Earth orbit spacecraft generally use 15 to 20 reflector layers (NASA TP-1999-209263, Section 4.1). The design trades mass and cost against radiative performance: each added reflector layer lowers the heat flow, but each layer adds areal weight.", "uses": [ { "where": "Spacecraft exteriors", "line": "Finckenor states that MLI protects spacecraft exteriors and also insulates cryogenic fluids for long periods (NASA TP-1999-209263, Section 7.8)." }, { "where": "Heat shield covering on a planetary probe", "line": "In late 1997 the Huygens probe on the Cassini spacecraft had to be removed for repairs to the MLI covering its heat shield, after launch-vehicle fans pulled and ripped the blanket (NASA TP-1999-209263, Section 7)." }, { "where": "Liquid hydrogen tank insulation", "line": "Lockheed tested double-aluminized 1/4-mil Mylar with double silk net spacers on a cryogen tank in vacuum, and modelled 30 days of liquid hydrogen storage in a space environment (NASA CR-72605, Summary)." } ], "can_do": [ { "label": "Radiative shielding", "line": "Double-aluminized Mylar has an infrared emittance of 0.03 typical and 0.05 maximum (NASA TP-1999-209263, Table 2). Measured total hemispherical emittance was 0.028 at 300 K (NASA CR-72605, Table 5-1).", "benchmark": "infrared_emittance", "scope": "material", "value": "0.03 typical, 0.05 maximum" }, { "label": "Temperature under heating", "line": "In a heat-pulse test at 1.5 mm Hg, the composite MLI with aluminized polyimide film reached a backface temperature of 110 °C at 15 min (NASA TM-101071, Conclusions item 2).", "benchmark": "backface_temperature", "scope": "material", "value": "110 °C at 15 min" }, { "label": "Continuous temperature range", "line": "Continuous maximum temperature is 93 °C for aluminized Mylar and 288 °C for aluminized Kapton (NASA TP-1999-209263, Table 2).", "benchmark": "max_service_temp", "scope": "material", "value": "93 °C (Mylar) and 288 °C (Kapton)" } ], "compare": "The composite MLI with aluminized polyimide film tested by Kourtides and Pitts reached a backface temperature of 110 °C at 15 min at 1.5 mm Hg, against 145 °C at 15 min for the silica-felt AFRSI of equivalent thickness and density (NASA TM-101071, Conclusions item 2). In vacuum the MLI's advantage is radiative: its reflector layers have an infrared emittance of 0.03 typical and 0.05 maximum for double-aluminized Mylar (NASA TP-1999-209263, Table 2). These are ground and handbook values; no in-orbit measurement for these films was found.", "compare_rows": [ { "label": "Infrared emittance, typical (double-aluminized Mylar)", "benchmark": "infrared_emittance", "scope": "material" }, { "label": "Solar absorptance, typical (double-aluminized Mylar)", "benchmark": "solar_absorptance", "scope": "material" }, { "label": "Maximum continuous service temperature", "benchmark": "max_service_temp", "scope": "material" } ], "handling": [ "Shrink the blanket before installation, as Finckenor advises for double-aluminized Mylar.", "Bake out any material that does not meet the outgassing requirement before assembly, to MSFC-SPEC-1238.", "Ground the layers to the structure with grounding straps or tape. Blankets over 1 m2 need at least two grounds.", "Keep ground-support airflow away from the blanket. Fans set too high ripped the Huygens MLI." ], "good_for": [ "Radiative insulation in vacuum. Double-aluminized Mylar has an infrared emittance of 0.03 typical (NASA TP-1999-209263, Table 2).", "Low mass per area. Aluminized Mylar of 0.025 mm (1.0 mil) weighs 0.0033 gm/cm2 (NASA TP-1999-209263, Table 2)." ], "watch_out": [ "Atomic oxygen in low Earth orbit erodes most organic materials, so exposed surfaces must be AO-resistant (NASA TP-1999-209263, Section 6.1).", "Long-term UV changes optical and mechanical properties (NASA TP-1999-209263, Section 6.2).", "Plasma charging in low Earth orbit can cause static discharge that damages electronics (NASA TP-1999-209263, Section 6.6).", "Double-aluminized Mylar may be limited to 120 °C where the blanket is sensitive to shrinkage (NASA TP-1999-209263, Table 2, footnote 1)." ], "verdict": "MLI is the reflective blanket for radiative insulation in vacuum. Double-aluminized Mylar gives low emittance at low mass, but exposed films need protection from atomic oxygen and UV.", "recipe": { "line": "Multilayer insulation is a stack of thin polymer films, each coated on one or both sides with vacuum-deposited aluminium, separated by spacer netting or scrim. Finckenor specifies that the metallized coating is a vacuum-deposited pure metal onto the polymer film substrate.", "parts": [ { "name": "Aluminium coating", "role": "Reflective metal layer, vacuum-deposited onto the film. It sets the low emittance and the solar absorptance in Table 2 of the guideline." }, { "name": "Polyester film (Mylar, PET)", "role": "Thin polymer substrate for the aluminium. Finckenor lists aluminized Mylar reflector layers in Table 2 across a range of thicknesses." }, { "name": "Polyimide film (Kapton)", "role": "Alternative substrate. Finckenor lists aluminized Kapton reflector layers in Table 2 across a range of thicknesses." }, { "name": "Spacer netting or scrim", "role": "Separates the foil layers so they do not short thermally. Kourtides gives eliminating heat shorts as the purpose of the scrim cloth. Finckenor Table 3 lists Dacron and Nomex netting." } ] }, "risk_groups": [ { "title": "For people", "lead": "The only hazard record read is PubChem's aggregated GHS data for aluminum metal. No safety data sheet or hazard record was read for the Mylar or Kapton films, so this profile gives no hazard classification for them.", "points": [ { "label": "Flammability", "line": "Finckenor states that MLI blankets must be tested for flammability before use." }, { "label": "Outgassing", "line": "Materials that do not meet the outgassing requirement must be baked out before assembly." } ], "verdict": "Aluminum GHS only; no film hazard record" }, { "title": "If a blanket is damaged", "lead": "These risks come from NASA guideline text and a documented flight-hardware event, not from laboratory data.", "points": [ { "label": "Ground handling", "line": "Ground-support airflow pulled and ripped the MLI on the Huygens probe; the probe had to be removed for repairs in late 1997." }, { "label": "Electrical", "line": "In low Earth orbit, plasma charging can cause static discharge that can severely damage key electrical components." }, { "label": "Atomic oxygen", "line": "Atomic oxygen erodes most organic materials, so exposed blanket surfaces must be AO-resistant." } ] }, { "title": "Handling and storage", "points": [ { "label": "Shrinkage", "line": "Finckenor advises shrinking the blanket before installation; the temperature range for double-aluminized Mylar may be limited to 120 °C where the blanket is sensitive to shrinkage." }, { "label": "Grounding", "line": "Grounding straps tie the layers to the primary structure. Blankets over 1 m2 need at least two grounds." } ] } ] }, "updated": "2026-11-01", "review": { "status": "draft", "method": "assistant", "checked_values": 23, "unreachable": 0, "caveats": 3, "note": "Written by an AI assistant on 2026-11-01 from three NASA reports and one USGS summary read in this run, with one Wikipedia page used only for composition. Values were copied from printed tables and checked against rendered page images for Table 2 (Finckenor) and Table 5-1 (CR-72605). The Kourtides values were read from text extraction. Deepen pass on 2026-11-01 added the DuPont Kapton HN and Mylar A datasheets (base films, unmetallized), the PubChem aluminum GHS record, and one NASA Glenn technical paper (qualitative, no numeric value)." }, "sources": { "finckenor1999": { "title": "NASA/TP-1999-209263: Multilayer Insulation Material Guidelines", "id": "NASA TP-1999-209263 (Marshall Space Flight Center)", "url": "https://ntrs.nasa.gov/citations/19990047691", "year": 1999, "kind": "handbook", "license": "public domain (NASA)" }, "cunnington1971": { "title": "NASA CR-72605 (LMSC-A903316): Thermal Performance of Multilayer Insulations, interim report", "id": "NASA CR-72605; Lockheed Missiles and Space Company, contract NAS3-12025", "url": "https://ntrs.nasa.gov/citations/19710014824", "year": 1971, "kind": "report", "license": "public domain (NASA)" }, "kourtides1989": { "title": "NASA TM-101071: Composite Multilayer Insulations for Thermal Protection of Aerospace Vehicles", "id": "NASA TM-101071 (Ames Research Center)", "url": "https://ntrs.nasa.gov/citations/19900000867", "year": 1989, "kind": "report", "license": "public domain (NASA)" }, "usgs-mcs2026-aluminum": { "title": "Mineral Commodity Summaries 2026: Aluminum", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "pubchem-aluminum": { "title": "PubChem compound record: Aluminum (CID 5359268), Safety and Hazards, GHS Classification", "id": "PubChem CID 5359268", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5359268", "year": 2026, "kind": "database", "license": "PubChem data (NIH), cited not reproduced" }, "dupont-kapton-hn": { "title": "DuPont Kapton HN polyimide film: technical datasheet (copy hosted on epectec.com)", "id": "DuPont Kapton HN datasheet, copyright 2016 DuPont (cites H-38479 and Bulletin GS-96-7)", "url": "https://www.epectec.com/downloads/DuPont-Kapton-HN-Polyimide-Film.pdf", "year": 2016, "kind": "datasheet", "license": "DuPont copyright, cited not reproduced" }, "mylar-a-datasheet": { "title": "Mylar A polyester film: technical datasheet, US customary units (Mylar Specialty Films)", "id": "Mylar Specialty Films, Mylar A datasheet, copyright 2024", "url": "https://mylar.com/wp-content/uploads/2025/08/mylar_a-1.pdf", "year": 2024, "kind": "datasheet", "license": "Mylar Specialty Films copyright, cited not reproduced" }, "nasa-ao-optical": { "title": "New Active Optical Technique Developed for Measuring Low-Earth-Orbit Atomic Oxygen Erosion of Polymers (NASA Glenn)", "id": "NASA NTRS 20050214723", "url": "https://ntrs.nasa.gov/citations/20050214723", "year": 2005, "kind": "report", "license": "public domain (NASA)" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/multilayer-insulation-mli/" }