{ "spore": "profile", "id": "carbon-dioxide-two-phase-coolant", "spore_version": "0.2", "family": "carbon-dioxide", "name": "Carbon dioxide (two-phase pumped-loop coolant)", "abbreviation": "CO2", "role": "coolant", "category": "thermal-protection", "type": "multi-layer-insulation", "summary": "Carbon dioxide (CO2) is one carbon atom bonded to two oxygen atoms. NIST's reference data put its triple point at 216.58 K and 5.185 bar, and its critical point at 304.18 K and 73.80 bar, so liquid CO2 exists only above the triple-point pressure. NASA used liquid carbon dioxide as the coolant in the pumped loop that cools the silicon tracker of the Alpha Magnetic Spectrometer (AMS-02) on the International Space Station.\n", "best_for": "Pumped cooling loops on a space instrument where the coolant can be refilled on orbit, as NASA planned for the AMS-02 tracker", "weakest_at": "Narrow margins: the liquid exists only above the 5.185 bar triple-point pressure, and the AMS-02 pumps are the documented failure point", "identity": { "formula": "CO2", "cas": "124-38-9", "designations": [], "source": "nist-phase", "where": "NIST WebBook compound page header: CAS Registry Number 124-38-9 and molecular weight 44.0095" }, "tags": { "environments": [], "stresses": [], "applications": [ "thermal-control" ] }, "properties": [ { "benchmark": "critical_temperature", "label": "Critical temperature", "value": 304.18, "bound": "exact", "unit": "K", "scope": "material", "conditions": { "phase": "critical point, liquid and vapour", "reference_row": "Suehiro, Nakajima, et al., 1996" }, "method": "Critical temperature as tabulated by NIST; NIST assigns an uncertainty of 0.04 K (TRC). Other rows in the same table give 304.1 K to 304.35 K.", "status": "ground", "source": "nist-phase", "where": "Phase change data table, Tc row (Suehiro, Nakajima, et al., 1996)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "critical_pressure", "label": "Critical pressure", "value": 73.8, "bound": "exact", "unit": "bar", "scope": "material", "conditions": { "phase": "critical point", "reference_row": "Suehiro, Nakajima, et al., 1996" }, "method": "Critical pressure as tabulated by NIST; NIST assigns an uncertainty of 0.15 bar (TRC).", "status": "ground", "source": "nist-phase", "where": "Phase change data table, Pc row (Suehiro, Nakajima, et al., 1996)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "critical_density", "label": "Critical density", "value": 10.6, "bound": "exact", "unit": "mol/l", "scope": "material", "conditions": { "phase": "critical point", "reference_row": "Suehiro, Nakajima, et al., 1996" }, "method": "Critical density as tabulated by NIST; NIST assigns an uncertainty of 0.05 mol/l (TRC). Angus et al. 1976 gives 10.590 mol/l.", "status": "ground", "source": "nist-phase", "where": "Phase change data table, rho c row (Suehiro, Nakajima, et al., 1996)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "critical_volume", "label": "Critical volume", "value": 0.0919, "bound": "exact", "unit": "l/mol", "scope": "material", "conditions": { "phase": "critical point" }, "method": "Critical volume as tabulated by NIST (uncertainty 0.001 l/mol, TRC).", "status": "ground", "source": "nist-phase", "where": "Phase change data table, Vc row (Li and Kiran, 1988)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "triple_point_temperature", "label": "Triple point temperature", "value": 216.58, "bound": "exact", "unit": "K", "scope": "material", "conditions": { "basis": "solid, liquid and vapour in equilibrium", "reference_row": "Marsh, 1987" }, "method": "Triple-point temperature as tabulated by NIST; NIST assigns an uncertainty of 0.008 K (TRC) and recommends it as a thermometry fixed point. Angus et al. 1976 gives the same 216.58 K.", "status": "ground", "source": "nist-phase", "where": "Phase change data table, Ttriple row (Marsh, 1987)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "triple_point_pressure", "label": "Triple point pressure", "value": 5.185, "bound": "exact", "unit": "bar", "scope": "material", "conditions": { "basis": "solid, liquid and vapour in equilibrium", "reference_row": "Angus, Armstrong, et al., 1976" }, "method": "Triple-point pressure as tabulated by NIST; NIST assigns an uncertainty of 0.005 bar (TRC).", "status": "ground", "source": "nist-phase", "where": "Phase change data table, Ptriple row (Angus, Armstrong, et al., 1976)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "molar_mass", "label": "Molecular weight", "value": 44.0095, "bound": "exact", "unit": "amu", "scope": "material", "conditions": { "basis": "molecular weight of CO2 as printed by NIST" }, "method": "Molecular weight as printed on the NIST WebBook compound page (IUPAC Gold Book link).", "status": "ground", "source": "nist-phase", "where": "Molecular weight line on the NIST WebBook page header", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "enthalpy_of_vaporization", "label": "Enthalpy of vaporization", "value": 16.7, "bound": "exact", "unit": "kJ/mol", "scope": "material", "conditions": { "temperature": "288 K", "basis": "liquid to vapour transition" }, "method": "Enthalpy of vaporization as tabulated by NIST from Stephenson and Malanowski, 1987, based on data from 273 K to 304 K.", "status": "ground", "source": "nist-phase", "where": "Enthalpy of vaporization table, first row (Stephenson and Malanowski, 1987)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "enthalpy_of_vaporization", "label": "Enthalpy of vaporization", "value": 16.4, "bound": "exact", "unit": "kJ/mol", "scope": "material", "conditions": { "temperature": "258 K", "basis": "liquid to vapour transition" }, "method": "Enthalpy of vaporization as tabulated by NIST from Stephenson and Malanowski, 1987, based on data from 216 K to 273 K.", "status": "ground", "source": "nist-phase", "where": "Enthalpy of vaporization table, second row (Stephenson and Malanowski, 1987)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "enthalpy_of_vaporization", "label": "Enthalpy of vaporization", "value": 16.5, "bound": "exact", "unit": "kJ/mol", "scope": "material", "conditions": { "temperature": "282 K", "basis": "liquid to vapour transition" }, "method": "Enthalpy of vaporization as tabulated by NIST from Boublik and Aim, 1972, based on data from 267 K to 303 K.", "status": "ground", "source": "nist-phase", "where": "Enthalpy of vaporization table, third row (Boublik and Aim, 1972)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "enthalpy_of_sublimation", "label": "Enthalpy of sublimation", "value": 26.1, "bound": "exact", "unit": "kJ/mol", "scope": "material", "conditions": { "temperature": "207 K", "basis": "solid to vapour transition" }, "method": "Enthalpy of sublimation as tabulated by NIST from Stephenson and Malanowski, 1987, based on data from 198 K to 216 K.", "status": "ground", "source": "nist-phase", "where": "Enthalpy of sublimation table, first row (Stephenson and Malanowski, 1987)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "enthalpy_of_sublimation", "label": "Enthalpy of sublimation", "value": 26.3, "bound": "exact", "unit": "kJ/mol", "scope": "material", "conditions": { "temperature": "167 K", "basis": "solid to vapour transition" }, "method": "Enthalpy of sublimation as tabulated by NIST from Stull, 1947, based on data from 139 K to 195 K.", "status": "ground", "source": "nist-phase", "where": "Enthalpy of sublimation table (Stull, 1947)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "enthalpy_of_sublimation", "label": "Enthalpy of sublimation", "value": 25.2, "bound": "exact", "unit": "kJ/mol", "scope": "material", "conditions": { "temperature": "195 K", "basis": "solid to vapour transition" }, "method": "Enthalpy of sublimation as tabulated by NIST from Giauque and Egan, 1937, based on data from 154 K to 196 K.", "status": "ground", "source": "nist-phase", "where": "Enthalpy of sublimation table (Giauque and Egan, 1937)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "enthalpy_of_formation_gas", "label": "Standard enthalpy of formation, gas", "value": -393.51, "bound": "exact", "unit": "kJ/mol", "scope": "material", "conditions": { "state": "gas at standard conditions", "uncertainty": "plus or minus 0.13 kJ/mol as printed" }, "method": "CODATA review value as printed by NIST (Cox, Wagman, et al., 1984). Chase, 1998 gives -393.52 kJ/mol.", "status": "ground", "source": "nist-thermo", "where": "Gas phase thermochemistry data, delta-f H gas row (Cox, Wagman, et al., 1984)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, gas phase thermochemistry data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Mask=1", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } }, { "benchmark": "entropy_gas_standard", "label": "Standard entropy, gas at 1 bar", "value": 213.785, "bound": "exact", "unit": "J/mol*K", "scope": "material", "conditions": { "state": "gas at 1 bar standard pressure", "uncertainty": "plus or minus 0.010 J/mol*K as printed" }, "method": "CODATA review value as printed by NIST (Cox, Wagman, et al., 1984). Chase, 1998 gives 213.79 J/mol*K.", "status": "ground", "source": "nist-thermo", "where": "Gas phase thermochemistry data, S gas row (Cox, Wagman, et al., 1984)", "source_detail": { "title": "NIST Chemistry WebBook: carbon dioxide, gas phase thermochemistry data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Mask=1", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" } } ], "corrosion": [], "risks": { "hazards": [ { "text": "PubChem's GHS entry for carbon dioxide gives H280: contains gas under pressure; may explode if heated. The signal word is Warning, and the pictogram is the compressed-gas symbol.", "ghs": [ "H280" ], "source": "pubchem-ghs", "where": "GHS Classification section, Hazard Statements (ECHA C&L entries, CID 280)" }, { "text": "PubChem also lists H281 for carbon dioxide: contains refrigerated gas; may cause cryogenic burns or injury. This applies to the cold liquid or refrigerated form.", "ghs": [ "H281" ], "source": "pubchem-ghs", "where": "GHS Classification section, Hazard Statements (ECHA C&L entries, CID 280)" } ], "failure_risks": [ { "mode": "Coolant pump wear-out in the AMS-02 tracker loop", "trigger": "Pumps run far beyond their original design life on orbit", "consequence": "NASA reported that most of the coolant pumps had stopped, and the last one ran only intermittently under good sunlight conditions, so the cooling system was close to stopping altogether.", "severity": "high", "source": "spaceflightnow-2019", "where": "Article paragraphs on the four coolant pumps and the expected loss of cooling" }, { "mode": "Leak in a cooling line after the loop is rebuilt", "trigger": "Fluid-line work during spacewalks", "consequence": "Leak checks are a required step before the loop is trusted. The 2020 spacewalk completed leak checks and opened a valve to begin pressurizing the system.", "severity": "moderate", "source": "nasa-2020-01-25", "where": "Spacewalk summary paragraph, leak checks and pressurization" } ], "side_effects": [], "handling": [ { "text": "Keep containers closed and away from heat. The gas is under pressure and may explode if heated (PubChem H280).", "source": "pubchem-ghs", "where": "GHS Classification section, H280 hazard statement" }, { "text": "Protect skin and eyes from refrigerated or liquid carbon dioxide, which can cause cryogenic burns (PubChem H281).", "source": "pubchem-ghs", "where": "GHS Classification section, H281 hazard statement" }, { "text": "Before cutting lines on orbit, the crew vented the carbon dioxide that remained in the old cooling pump.", "source": "nasa-2019-11-22", "where": "Summary paragraph on tube cutting and venting" }, { "text": "After leak checks, ground teams filled the new AMS thermal control system with carbon dioxide and then powered the pumps.", "source": "nasa-2020-01-25", "where": "Spacewalk summary paragraph, fill and pump power-on" } ], "mitigations": [] }, "uses": [ { "application": "thermal-control", "device": "AMS-02 silicon tracker coolant loop on the International Space Station (flight, original pumped system)", "example": "NASA's spacewalk reporting describes the AMS tracker coolant as liquid carbon dioxide, which the astronauts would replenish during the repair spacewalks.", "source": "spaceflightnow-2019", "where": "Article paragraph on carbon dioxide coolant and replenishment" }, { "application": "thermal-control", "device": "Upgraded tracker thermal pump system on the International Space Station (flight, installed during spacewalks)", "example": "The crew installed the upgraded tracker thermal pump system and connected all the AMS cooling lines to the new system by swaging, a metalworking connection.", "source": "nasa-2019-12-02", "where": "Spacewalk summary paragraph on the upgraded tracker thermal pump system" } ], "supply": [ { "subject": "Carbon dioxide (industrial supply)", "producers": [], "critical_lists": [], "recycling": "Not stated in the source used.", "substitutes": [], "source": "wiki-co2", "where": "Industrial and geological sources section: byproduct of hydrogen production by steam reforming and of ammonia production, and from natural gas processing. No country production shares are given." } ], "media": [], "documents": [ { "title": "NIST WebBook: carbon dioxide phase change data (CAS 124-38-9)", "type": "database", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026 }, { "title": "NIST WebBook: carbon dioxide gas phase thermochemistry", "type": "database", "url": "https://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Mask=1", "year": 2026 }, { "title": "PubChem: Carbon dioxide (CID 280), GHS classification", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/280", "year": 2026 }, { "title": "NASA Space Station blog: second cosmic repair spacewalk", "type": "report", "url": "https://www.nasa.gov/blogs/spacestation/2019/11/22/astronauts-complete-intricate-tasks-during-second-cosmic-repair-spacewalk/", "year": 2019 } ], "gaps": [ "No flight or space-environment test data for the fluid's own properties in any source fetched; the only space source is the AMS-02 operations record.", "Corrosion or material-compatibility data for carbon dioxide in cooling-line materials were not found in any source opened, so the corrosion section is left out.", "Two-phase operation: the planner's name says two-phase, but none of the fetched sources calls the AMS-02 loop two-phase. They describe liquid carbon dioxide in a pumped loop. The name is kept as the planner gave it and is not verified.", "No country production shares for carbon dioxide were found; the supply section is qualitative and cites the Wikipedia sources section.", "No USGS or EU critical-minerals entry was checked for carbon dioxide, so critical_lists is left empty.", "Property names are not in spores/property-canon.yaml and were not invented to match it: critical_temperature, critical_pressure, critical_density, critical_volume, triple_point_temperature, triple_point_pressure, molar_mass, enthalpy_of_vaporization, enthalpy_of_sublimation, enthalpy_of_formation_gas and entropy_gas_standard.", "NIST gives several critical-point rows from different references (for example 304.1 K to 304.35 K). Only one row is recorded per quantity; the others are named in the method text.", "No safety data sheet for carbon dioxide was opened. PubChem's ECHA-derived GHS entry was read through its REST view, because the HTML page showed a bot check.", "NIST fit coefficients (Antoine and Shomate) were not recorded as properties.", "Spaceflight Now blocks automated access, so its statements were read through WebFetch in this run and are not checked by the value script.", "Carbon dioxide's loop temperature and pressure operating ranges were not found in any source opened.", "No thermal-protection type fits a coolant. The type is set to multi-layer-insulation, the same as the methanol heat-pipe fluid profile, because the schema requires a type; a coolant type would need a taxonomy change." ], "story": { "why": "Carbon dioxide is a coolant that stays liquid only under pressure. NASA's tracker cooling on the International Space Station circulated liquid carbon dioxide through a pumped loop, which is why its phase data matter for the design. The triple point and critical point set the pressure and temperature window in which the liquid can be held.", "uses": [ { "where": "AMS-02 tracker on the International Space Station", "line": "NASA's spacewalk reports describe liquid carbon dioxide as the coolant of the AMS-02 silicon tracker. The crew replenished the instrument with it during the repair spacewalks." }, { "where": "Upgraded tracker thermal pump system", "line": "The upgraded system was installed on a later spacewalk and connected to the existing AMS cooling lines, with the new loop filled with carbon dioxide after leak checks." } ], "can_do": [ { "label": "Strength", "line": "Carry heat away in a pumped liquid loop on a space instrument, as the AMS-02 tracker did.", "scope": "material" }, { "label": "Strength", "line": "Be refilled on orbit during spacewalks, which NASA planned for the AMS-02 tracker.", "scope": "material" }, { "label": "Strength", "line": "Stay liquid only above its triple-point pressure of 5.185 bar, at its triple-point temperature of 216.58 K and above.", "scope": "material" } ], "compare": "NIST's reference data for carbon dioxide give a critical point at 304.18 K and 73.80 bar, a triple point at 216.58 K and 5.185 bar, and an enthalpy of vaporization of 16.7 kJ/mol at 288 K. The table below lists three of these values. No other cooling fluid is compared, because the sources read for this profile give no same-basis values for one.", "compare_rows": [ { "label": "Critical temperature", "benchmark": "critical_temperature", "scope": "material" }, { "label": "Triple point temperature", "benchmark": "triple_point_temperature", "scope": "material" }, { "label": "Enthalpy of vaporization", "benchmark": "enthalpy_of_vaporization", "scope": "material" } ], "handling": [ "Keep the container closed and away from heat. The gas is under pressure and may explode if heated.", "Protect skin and eyes from refrigerated or liquid carbon dioxide, which can cause cryogenic burns.", "On orbit, refill the loop only after leak checks, as the NASA crew and ground teams did." ], "good_for": [ "Pumped cooling loops on space instruments, where NASA used liquid carbon dioxide on the AMS-02 tracker.", "Reference thermodynamic data: NIST gives the triple point and critical point with stated uncertainties." ], "watch_out": [ "Pumps: the AMS-02 record shows coolant pumps that wore out well past their design life.", "Pressure: the liquid exists only above the triple-point pressure of 5.185 bar.", "Heat: the gas is under pressure and may explode when heated (PubChem H280)." ], "verdict": "Carbon dioxide has well-measured phase data for a pumped loop. On the AMS-02 record, the pumps failed before the fluid did, and the repair was a refill and replacement of the loop.", "recipe": { "line": "Carbon dioxide has one carbon atom bonded to two oxygen atoms. Industrially it is recovered as a byproduct of hydrogen production by steam reforming and of ammonia production, and from natural gas processing.", "parts": [ { "name": "Carbon", "symbol": "C", "role": "The central atom. Each carbon atom is bonded to two oxygen atoms in the molecule." }, { "name": "Oxygen", "symbol": "O", "role": "The two outer atoms. Together with the carbon they make a molecule of molar mass 44.0095 amu." } ] }, "risk_groups": [ { "title": "For people", "lead": "PubChem lists the compressed-gas hazard (H280) and the cold-burn hazard (H281) for carbon dioxide.", "points": [ { "label": "Pressure", "line": "The gas is under pressure and may explode if heated. Keep containers away from heat." }, { "label": "Cold", "line": "Refrigerated or liquid carbon dioxide can cause cryogenic burns or injury." } ], "level": 1, "verdict": "Compressed gas; cold liquid can cause burns" }, { "title": "If a pumped loop fails", "lead": "The AMS-02 record shows how coolant-loop trouble appeared on orbit.", "points": [ { "label": "Pumps", "line": "Most of the coolant pumps had stopped, and the last one ran only intermittently under good sunlight conditions." }, { "label": "Repair", "line": "The repair installed a new loop on spacewalks, followed by leak checks and a refill with carbon dioxide." } ] }, { "title": "Handling and storage", "points": [ { "label": "Storage", "line": "Keep containers closed and away from heat, since the gas may explode when heated." }, { "label": "Venting", "line": "The crew vented the carbon dioxide left in the old pump before cutting its lines." } ] } ] }, "updated": "2026-11-01", "review": { "status": "draft", "method": "assistant", "checked_values": 15, "unreachable": 0, "caveats": 1, "note": "Written by an AI assistant on 2026-11-01. NIST and PubChem values were checked against the raw pages in this run." }, "sources": { "nist-phase": { "title": "NIST Chemistry WebBook: carbon dioxide, phase change data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?Mask=4&ID=C124389", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" }, "nist-thermo": { "title": "NIST Chemistry WebBook: carbon dioxide, gas phase thermochemistry data (NIST SRD 69)", "id": "CAS 124-38-9", "url": "https://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Mask=1", "year": 2026, "kind": "database", "license": "NIST Standard Reference Data (cited, not reproduced)" }, "pubchem-ghs": { "title": "PubChem compound record, Carbon dioxide (CID 280), GHS classification", "id": "CID 280", "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/280/JSON?heading=GHS+Classification", "year": 2026, "kind": "database", "license": "public domain (NCBI)" }, "nasa-2019-11-22": { "title": "Astronauts Complete Intricate Tasks During Second Cosmic Repair Spacewalk (NASA blog)", "id": "NASA Space Station blog, 22 November 2019", "url": "https://www.nasa.gov/blogs/spacestation/2019/11/22/astronauts-complete-intricate-tasks-during-second-cosmic-repair-spacewalk/", "year": 2019, "kind": "web", "license": "public domain (NASA)" }, "nasa-2019-12-02": { "title": "Astronauts Wrap Up Third Spacewalk for Cosmic Particle Detector Repairs (NASA blog)", "id": "NASA Space Station blog, 2 December 2019", "url": "https://www.nasa.gov/blogs/spacestation/2019/12/02/astronauts-wrap-up-third-spacewalk-for-cosmic-particle-detector-repairs/", "year": 2019, "kind": "web", "license": "public domain (NASA)" }, "nasa-2020-01-25": { "title": "Astronauts Wrap Up Spacewalk Repair Job on Cosmic Ray Detector (NASA blog)", "id": "NASA Space Station blog, 25 January 2020", "url": "https://www.nasa.gov/blogs/spacestation/2020/01/25/astronauts-wrap-up-spacewalk-repair-job-on-cosmic-ray-detector/", "year": 2020, "kind": "web", "license": "public domain (NASA)" }, "spaceflightnow-2019": { "title": "Repair equipment for particle physics experiment aboard next station cargo launch (Spaceflight Now)", "id": "Spaceflight Now, 1 November 2019", "url": "https://spaceflightnow.com/2019/11/01/repair-equipment-for-particle-physics-experiment-aboard-next-station-cargo-launch/", "year": 2019, "kind": "web", "license": "news article, linked not reproduced" }, "wiki-co2": { "title": "Carbon dioxide (Wikipedia), sections on industrial sources and refrigerant use", "id": "Wikipedia article, Carbon dioxide", "url": "https://en.wikipedia.org/wiki/Carbon_dioxide", "year": 2026, "kind": "web", "license": "CC BY-SA 4.0 (linked, not reproduced)" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/carbon-dioxide-two-phase-coolant/" }