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Photo of person holding flask containing reddish liquid
An Erlenmeyer flask containing about two litres (1⁄2 US gallon) of RP-1

RP-1 (Rocket Propellant-1 or Refined Petroleum-1) and similar fuels like RG-1 and T-1 are highly refined kerosene formulations used as rocket fuel. Liquid-fueled rockets that use RP-1 as fuel are known as kerolox rockets. In their engines, RP-1 is atomized, mixed with liquid oxygen (LOX), and ignited to produce thrust. Developed in the 1950s, RP-1 is outwardly similar to other kerosene-based fuels like Jet A and JP-8 used in turbine engines but is manufactured to stricter standards. While RP-1 is widely used globally, the primary rocket kerosene formulations in Russia and other former Soviet countries are RG-1 and T-1, which have slightly higher densities.

Compared to other rocket fuels, RP-1 provides several advantages with a few tradeoffs. Compared to liquid hydrogen, it offers a lower specific impulse, but can be stored at ambient temperatures, has a lower explosion risk, and although its specific energy is lower, its higher density results in greater energy density. Compared to hydrazine, another liquid fuel that can be stored at ambient temperatures, RP-1 is far less toxic and carcinogenic.

Usage and history

[edit]
Photo of Saturn V rocket lifting off
Apollo 8, Saturn V with 810,700 litres of RP-1 and 1,311,100 liters of LOX in the S-IC first stage[1]

RP-1 is a fuel in the first-stage boosters of the Electron, Soyuz, Zenit, Delta I-III, Atlas, Falcon, Antares, and Tronador II rockets. It also powered the first stages of the Energia, Titan I, Saturn I and IB, and Saturn V. The Indian Space Research Organization (ISRO) is also developing an RP-1 fueled engine for its future rockets.[2][needs update]

Development

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During and immediately after World War II, alcohols (primarily ethanol, occasionally methanol) were commonly used as fuels for large liquid-fueled rockets. Their high heat of vaporization kept regeneratively-cooled engines from melting, especially considering that alcohols would typically contain several percent water. However, it was recognized that hydrocarbon fuels would increase engine efficiency, due to a slightly higher density, the lack of an oxygen atom in the fuel molecule, and negligible water content. Regardless of which hydrocarbon was chosen, it would also have to replace alcohol as a coolant.

Many early rockets burned kerosene, but as burn times, combustion efficiencies, and combustion-chamber pressures increased, engine masses decreased, which led to unmanageable engine temperatures. Raw kerosene used as coolant tends to dissociate and polymerize. Lightweight products in the form of gas bubbles cause cavitation, and heavy ones in the form of wax deposits block narrow cooling passages in the engine. The resulting coolant starvation raises temperatures further, and causes more polymerization which accelerates breakdown. The cycle rapidly escalates (i.e., thermal runaway) until an engine wall rupture or other mechanical failure occurs, and it persists even when the entire coolant flow consists of kerosene. In the mid-1950s rocket designers turned to chemists to formulate a heat-resistant hydrocarbon, with the result being RP-1.

During the 1950s, LOX (liquid oxygen) became the preferred oxidizer to use with RP-1,[3] though other oxidizers have also been employed.

Fractions and formulation

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RP-1 is outwardly similar to other kerosene-based fuels, but is manufactured to stricter standards. These include tighter density and volatility ranges, along with significantly lower sulfur, olefin, and aromatic content.[4]

Sulfur and sulfur compounds attack metals at high temperatures, and even very small amounts of sulfur assist polymerization which can harden seals and tubing, therefore sulfur and sulfur compounds are kept to a minimum.

Unsaturated compounds (alkenes, alkynes, and aromatics) are also held to low levels, as they tend to polymerize at high temperatures and long periods of storage. At one time, it was thought that kerosene-fueled missiles might remain in storage for years awaiting activation. This function was later transferred to solid-fuel rockets, though the high-temperature benefits of saturated hydrocarbons remained. Because of the low levels of alkenes and aromatics, RP-1 is less toxic than various jet and diesel fuels, and far less toxic than gasoline.

The more desirable isomers were selected or synthesized, with linear alkanes being reduced in number in favor of greater numbers of cyclic and highly branched alkanes. Just as cyclic and branched molecules improve octane rating in petrol, they also significantly increase thermal stability at high temperatures. The most desirable isomers are polycyclics such as ladderanes.

In contrast, the main applications of kerosene (aviation, heating, and lighting), are much less concerned with thermal breakdown and therefore do not require stringent optimisation of their isomers.

In production, these grades are processed tightly to remove impurities and side fractions. Ashes were feared likely to block fuel lines and engine passages, and wear away valves and turbopump bearings, as these are lubricated by the fuel. Slightly too-heavy or too-light fractions affected lubrication abilities and were likely to separate during storage and under load. The remaining hydrocarbons are at or near C12 mass. Because of the lack of light hydrocarbons, RP-1 has a high flash point and is less of a fire hazard than petrol.

All told, the final product is much more expensive than common kerosene. Any petroleum can produce RP-1 with enough refining, though real-world rocket-grade kerosene is sourced from a small number of oil fields with high-quality base stock, or it can be artificially synthesized. This, coupled with the relatively small demand in a niche market compared to other petroleum users, drives RP-1's high price. Military specifications of RP-1 are covered in MIL-R-25576,[5] and the chemical and physical properties of RP-1 are described in NISTIR 6646.[6]

In Russia and other former Soviet countries, the two main rocket kerosene formulations are T-1 and RG-1. Densities are slightly higher, 0.82 to 0.85 g/mL, compared to RP-1 at 0.81 g/mL.

The Soviets also discovered that even higher densities could be achieved by chilling the kerosene before loading it into the rocket's fuel tanks, although this partially defeated the purpose of using kerosene over other super-chilled fuels. However, operationally, facilities were already in place to manage the vehicle's cryogenic liquid oxygen and liquid nitrogen, both of which are far colder than the kerosene. The launcher's central kerosene tank is surrounded on four sides and the top by liquid oxygen tanks with a liquid nitrogen tank at the bottom. The kerosene tanks of the four boosters are relatively small and compact, also located between a liquid oxygen and a liquid nitrogen tank. Thus, once the kerosene was initially chilled, it would remain cold for the brief time needed to finish launch preparations.

While the Soviets would eventually abandon chilling their kerosene, decades later SpaceX would revisit the idea for their Falcon 9 rocket. All versions since the Falcon 9 Full Thrust have used sub-cooled RP-1, chilled to −7 °C (19 °F), giving a 2.5%–4% density increase.[7]

Comparison with other fuels

[edit]
LOX/kerosene
Isp at sea level[5][8] 220–301.5 s
Isp in vacuum[5][8] 292–340 s
Oxidizer-to-fuel ratio 2.56
Density (g/mL) 0.81–1.02
Heat capacity ratio 1.24
Temperature of combustion 3,670 K

Chemically, a hydrocarbon propellant is less mass-efficient than hydrogen, although typically achieving a higher density and simpler handling than hydrogen.

For rocket engines, specific impulse (Isp) differs from other engines' (turbines' or pistons') efficiencies: due to the rocket equation, efficiency is derived from exhaust velocity, not from total energy. As such, it can be beneficial to use less energy overall in exchange for lower-molecular-mass exhaust, meaning that chemical rocket engines achieve their peak efficiency at non-stoichiometric ratios. In particular, since the oxygen is heavier than the carbon or hydrogen, essentially all combustion rocket engines run fuel-rich to reduce the exhaust molecular mass, increasing exhaust velocity and thus specific impulse (and as a side benefit, temperature and cooling are reduced too). This effect favors lighter elements like pure hydrogen. However, total thrust also matters, especially deep inside a gravity well, and the density of kerosene enables considerably higher power and thrust than hydrogen (relative to engine mass).

All told, due to higher energy-per-mass and lower molecular mass, hydrogen engines achieve 370 to 465 s, while kerosene engines generate an Isp in the range of 270 to 360 s; conversely, kerosene has the better handling, density, and thrust-to-weight properties. One common solution is to use a multistage rocket, where the first stage uses kerosene where thrust matters most, and the upper stages use hydrogen where specific impulse matters more. Examples of this dual-fuel architecture include the Saturn V moon rocket and the Atlas V workhorse.

Methane serves as a middle-ground between hydrogen and kerosene, offering middling molecular mass and efficiency, middling handling, middling coking/buildup properties, and density only slightly worse than kerosene. Since methane's handling difficulties, while worse than kerosene, are about the same as liquid oxygen, that means a methlox rocket is nearly as easy to handle as a kerolox rocket, but with the improved efficiency and cleanliness (which remain worse than hydrogen). Furthermore, these balances in efficiency-vs-power makes methane more suitable for a single-fuel rocket, which have proven more economical than dual-fuel rockets (due to less complexity). As such, methalox has made a resurgence in popularity in 21st century rockets, at the expense of kerolox (better efficiency) and hydrolox (better handling). Examples include Starship, New Glenn, the first stage of Vulcan, and Zhuque-2.

During engine shutdown, fuel flow goes to zero rapidly, while the engine is still quite hot. Residual and trapped fuel can polymerize or even carbonize at hot spots or in hot components. Even without hot spots, heavy fuels can create a petroleum residue, as can be seen in gasoline, diesel, or jet fuel tanks that have been in service for years. Rocket engines have cycle lifetimes measured in minutes or even seconds, preventing truly heavy deposits. However, rockets are much more sensitive to a deposit, as described above. Thus, kerosene systems generally entail more teardowns and overhauls, creating operations and labor expenses. This is a problem for expendable engines, as well as reusable ones, because engines must be ground-fired some number of times before launch. Even cold-flow tests, in which the propellants are not ignited, can leave residues.

On the upside, below a chamber pressure of about 1,000 psi (7 MPa), kerosene can produce sooty deposits on the inside of the nozzle and chamber liner. This acts as a significant insulation layer and can reduce the heat flow into the wall by roughly a factor of two. Most modern hydrocarbon engines, however, run above this pressure, therefore this is not a significant effect for most engines.

Recent heavy-hydrocarbon engines have modified components and new operating cycles, in attempts to better manage leftover fuel, achieve a more-gradual cooldown, or both. This still leaves the problem of non-dissociated petroleum residue. Other new engines have tried to bypass the problem entirely, by switching to light hydrocarbons such as methane or propane gas. Both are volatiles, so engine residues simply evaporate. If necessary, solvents or other purgatives can be run through the engine to finish dispersion. The short-chain carbon backbone of propane (a C3 molecule) is very difficult to break; methane, with a single carbon atom (C1), is technically not a chain at all. The breakdown products of both molecules are also gases, with fewer problems due to phase separation, and much less likelihood of polymerization and deposition. However, methane (and to a lesser extent propane) reintroduces handling inconveniences that prompted kerosenes in the first place.

The low vapor pressure of kerosenes gives safety for ground crews. However, in flight the kerosene tank needs a separate pressurization system to replace fuel volume as it drains. Generally, this is a separate tank of liquid or high-pressure inert gas, such as nitrogen or helium. This adds extra cost and weight. Cryogenic or volatile propellants generally do not need a separate pressurant; instead, some propellant is expanded (often with engine heat) into low-density gas and routed back to its tank. A few highly volatile propellant designs do not even need the gas loop; some of the liquid automatically vaporizes to fill its own container. Some rockets use gas from a gas generator to pressurize the fuel tank; usually, this is exhaust from a turbopump. Although this saves the weight of a separate gas system, the loop now has to handle a hot, reactive gas instead of a cool, inert one.

Regardless of chemical constraints, RP-1 has supply constraints due to the very small size of the launch-vehicle industry versus other consumers of petroleum. While the material price of such a highly refined hydrocarbon is still less than many other rocket propellants, the number of RP-1 suppliers is limited. A few engines have attempted to use more standard, widely distributed petroleum products such as jet fuel or even diesel (for example, ABL Space Systems' E2 engine can run on either RP-1 or Jet-A). By using alternate or supplemental engine cooling methods, some engines can tolerate the non-optimal formulations.

Any hydrocarbon-based fuel produces more air pollution when burned than hydrogen alone. Hydrocarbon combustion produces carbon dioxide (CO2), carbon monoxide (CO), and hydrocarbon (HC) emissions, while hydrogen (H2) reacts with oxygen (O2) to produce only water (H2O), with some unreacted H2 also released. Both hydrocarbon-based fuels and hydrogen fuel will create oxides of nitrogen (NOx) pollutants, because rocket exhaust temperatures above 1,600 °C (2,900 °F) will thermally combine some of the nitrogen (N2) and oxygen (O2) already present in the atmosphere, to create oxides of nitrogen.

RP-1-like fuels

[edit]

Robert H. Goddard's initial rockets used gasoline.

While the RP-1 specification was being developed, Rocketdyne was experimenting with diethyl cyclohexane. While superior to RP-1, it was never adopted for use – its formulation was not finished before development of Atlas and Titan I (designed around RP-1) leading to RP-1 becoming the standard hydrocarbon rocket fuel.[9]

Soviet formulations are discussed above. In addition, the Soviets briefly used syntin (Russian: синтин), a higher-energy formulation, used in upper stages. Syntin is 1-methyl-1,2-dicyclopropyl cyclopropane (C
10H
16). Russia is also working to switch the Soyuz-2 from RP-1 to "naftil"[10] or "naphthyl".[11][12]

After the RP-1 standard, RP-2 was developed. The primary difference is an even lower sulfur content. However, as most users accept RP-1, there was little incentive to produce and stock a second, even rarer and more expensive formulation.

The OTRAG group launched test vehicles using more common blends. In at least one instance, a rocket was propelled by diesel fuel. However, no OTRAG rocket came even close to orbit.[citation needed]

References

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Further reading

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[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

RP-1

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from Grokipedia
RP-1 (Rocket Propellant-1) is a highly refined, kerosene-based liquid fuel specifically formulated for use in rocket engines, consisting of a complex mixture of hydrocarbons including linear and branched paraffins, cycloparaffins, and minor amounts of aromatics and olefins. Developed in the 1950s to meet military specification MIL-P-25576 for consistent performance and stability, RP-1 is designed to minimize coking and deposits in high-temperature combustion environments while providing high energy density. It is typically paired with liquid oxygen (LOX) as an oxidizer in bipropellant systems, enabling efficient thrust generation in both first-stage boosters and upper stages. Key properties of RP-1 include a of approximately 806 kg/m³ at 15°C, a around 164 g/mol, and a hydrogen-to-carbon ratio of about 1.95, which contribute to its favorable characteristics. The is storable at ambient temperatures without significant degradation, unlike cryogenic propellants, and has low content (typically under 30 ppm by mass) to enhance thermal stability. When burned with , RP-1 achieves a vacuum of up to 314 seconds in engines, balancing simplicity, reliability, and performance. RP-1 has been a cornerstone of rocketry since the mid-20th century, powering notable engines such as the F-1 used in the Saturn V's first stage for Apollo missions and the Merlin engines in SpaceX's Falcon 9 and Falcon Heavy launch vehicles. It is also employed in the Atlas V rocket for missions like NASA's New Horizons probe to Pluto. Its widespread adoption stems from ease of handling, cost-effectiveness, and compatibility with turbopump-fed systems, though ongoing research explores enhancements like gelled variants for improved safety and efficiency.

Definition and Properties

Chemical Composition

RP-1 is a refined kerosene-based consisting primarily of a complex mixture of saturated aliphatic hydrocarbons with carbon chain lengths ranging from C9 to C16. These hydrocarbons are predominantly branched-chain alkanes and cyclic paraffins (naphthenes), such as isododecane and , which constitute approximately 33% straight and branched alkanes and 67% cycloalkanes, contributing to an average hydrogen-to-carbon (H/C) of about 2.0. The overall composition yields an approximate molecular formula of C11.66H23.32, often simplified to C12H24 for modeling purposes. To ensure compatibility with components, RP-1 maintains low levels of impurities that could lead to , deposits, or incomplete . Aromatics are restricted to a maximum of 5% by volume, with typical content much lower (often near 0%), while olefins are limited to a maximum of 2% by volume. content is capped at 30 mg/kg (0.003% by weight) to minimize catalytic effects on fuel decomposition and material degradation. These specifications, outlined in MIL-DTL-25576F, exclude additives such as or , relying instead on the inherent purity of the refined hydrocarbons. The formulation emphasizes thermal stability, allowing RP-1 to withstand temperatures up to approximately 400°C without significant cracking or decomposition, which is critical for in high-performance engines. This stability arises from the saturated nature of its hydrocarbons, which resist auto-oxidation below pyrolysis thresholds around 482°C. For combustion, RP-1 undergoes oxidation with , approximated by the simplified reaction: C12H24+18 O2→12 CO2+12 H2O\mathrm{C_{12}H_{24} + 18\, O_2 \rightarrow 12\, CO_2 + 12\, H_2O} This represents complete stoichiometric combustion, requiring an oxygen-to-fuel of about 3.43 for full conversion of carbon and hydrogen, though practical mixtures are fuel-rich to optimize .

Physical and Thermodynamic Properties

RP-1, a highly refined , possesses physical properties that ensure its suitability for high-performance systems. Its is typically 0.81 g/cm³ at 15 °C, corresponding to a specific of 0.81, though minor variations between 0.799 and 0.816 g/cm³ ( 42.0° to 45.5°) at 15.56 °C can occur depending on the exact formulation and process. This range supports efficient storage and pumping in tanks. The freezing point is below -50 °C, providing compatibility with cryogenic environments without solidification under operational conditions. The of RP-1 spans a range of 180–275 °C, reflecting its multicomponent nature, which allows for controlled vaporization during . Viscosity measures 1.0–2.5 cSt at 20 °C, contributing to favorable flow characteristics in fuel lines and injectors, while is approximately 25–30 dyn/cm, aiding in atomization processes. Key thermodynamic properties include a of approximately 43 MJ/kg, which underpins its high energy release in engines. The is around 2.0 kJ/kg·, influencing during storage and operation, and thermal conductivity is about 0.13 W/m·, relevant for cooling applications.
PropertyValueConditionsSource
Density0.81 g/cm³ (specific gravity 0.81)15 °CNISTIR 6646
Boiling point range180–275 °CMIL-DTL-25576E
Freezing point< -50 °C-MIL-DTL-25576E
Viscosity1.0–2.5 cSt20 °CNISTIR 6646
Surface tension25–30 dyn/cm20 °CRocketProps ( data)
Heat of combustion~43 MJ/kgStandardAIAA 2004-3879
Heat capacity~2.0 kJ/kg·K25 °CRocketProps ( data)
Thermal conductivity~0.13 W/m·K25 °CNISTIR 6646
When paired with () in bipropellant systems, RP-1 demonstrates minimal volume contraction upon to temperatures around -7 °C, enhancing overall density with limited handling challenges compared to fully .

Performance Specifications

RP-1, paired with in kerolox engines at a typical oxidizer-to-fuel mixture ratio of 2.3:1 by , provides a of 220–301 seconds at and 292–340 seconds in vacuum, depending on engine design and . These values reflect the propellant's moderate energy release compared to cryogenic alternatives, balanced by reliable ignition and stable characteristics. The high of RP-1 (approximately 0.81 g/cm³ at 25°C) enables superior density in systems, facilitating compact tank designs that reduce structural mass and improve overall vehicle efficiency. RP-1 supports storage in an operational range of -7°C to +60°C, with chilling to the lower end often employed to enhance for launch performance. Its ignition limits include a exceeding 60°C and an of approximately 220°C, as defined in military specification MIL-PRF-25576E, ensuring safe handling and minimal fire risk during ground operations. In turbopump-fed engines, kerolox with RP-1 achieves efficiencies greater than 95%, contributing to consistent output and high .

History and Development

Early Origins in Rocket Fuels

The development of RP-1 originated in the post-World War II era, as rocketry transitioned from alcohol-based propellants to hydrocarbons to achieve higher performance and practicality. During WWII, the German V-2 rocket relied on a mixture of 75% ethanol and 25% water as fuel, combined with liquid oxygen, providing a specific energy of approximately 20 MJ/kg but limited by lower density and combustion efficiency compared to hydrocarbons. Post-war U.S. engineers, building on captured V-2 technology, sought fuels with greater energy density—around 43 MJ/kg for kerosene variants—to enable longer-range missiles while improving storability and reducing volatility. This shift was driven by the need for propellants that could support sustained high-thrust operations without the dilution effects of water in alcohol mixes. In the late 1940s, the U.S. Army and initiated extensive testing of fuels for guided missiles, focusing on readily available derivatives like wide-cut , a precursor to jet fuels such as JP-4. These early experiments revealed significant challenges, including coking—carbon deposits that clogged engine nozzles and cooling channels—due to incomplete combustion and aromatic impurities in the fuels. Conducted at facilities like the (JPL) and Reaction Motors, Inc. (RMI), the tests paired hydrocarbons with oxidizers like (RFNA) or , highlighting the need for cleaner-burning formulations to prevent engine failures in prolonged burns. By the early 1950s, the (NACA) and contractors like Rocketdyne intensified efforts through programs such as the Navaho missile project, which demanded a stable, high-performance fuel for ramjet-boosted liquid rocket stages. Testing identified that low-aromatic variants minimized deposits and improved heat transfer in systems, outperforming broader-cut fuels. In the early 1950s, efforts at NACA and contractors refined -based propellants to minimize deposits and improve combustion stability with . These efforts culminated in the Rocketdyne Engine Advancement Program (REAP) starting in 1953, which standardized the grade later designated RP-1 for Navaho and subsequent missile applications.

Standardization Efforts

The U.S. Air Force formalized RP-1 as a standard rocket fuel in 1957 through Military Specification MIL-R-25576, establishing precise requirements for a highly refined to support the Navaho and Thor programs. This specification emphasized low residue, consistent distillation characteristics, and minimal impurities to ensure reliable ignition and combustion in /kerosene engines. In the , the specification underwent updates to optimize fractions for enhanced thermal stability and performance in the Apollo program's first stage. These refinements included stricter controls on aromatic content and volatility to meet the demands of high-thrust F-1 engines, enabling consistent propellant delivery during manned lunar missions. Internationally, the Soviet Union developed a comparable specification for RG-1 kerosene in the 1950s, tailored for the R-7 Semyorka intercontinental ballistic missile and subsequent launch vehicles. RG-1 shared RP-1's high density (0.82–0.85 g/ml) and low olefin content but featured slightly higher aromatic levels, supporting the R-7's debut in the 1957 Sputnik launch and ongoing Soyuz operations. Key milestones in RP-1 standardization included 1970s revisions to the MIL-R-25576 specification, which introduced RP-2 with a total limit of less than 1 ppm, while RP-1 remained under 30 ppm, to mitigate corrosion and deposit formation in channels of evolving engine designs requiring higher operating temperatures. This addressed sulfur-induced degradation that could compromise mission reliability. Further advancements came with the NISTIR 6646 report, which detailed comprehensive analysis using gas chromatography-mass spectrometry to quantify compositional variability and promote batch-to-batch consistency across RP-1 samples. These efforts derived performance specifications emphasizing (0.815–0.825 g/ml at 15°C) and limits, as detailed in the Performance Specifications section.

Production and Formulation

Refining Processes

RP-1 is produced starting from straight-run distillate, which is the fraction collected during the atmospheric of crude oil with a boiling range of approximately 180–260°C. This initial feedstock consists primarily of hydrocarbons in the C9–C15 range but requires extensive purification to meet the stringent specifications for use. The core refining involves hydrotreating, a process conducted at temperatures of 340–400°C and pressures of 40–80 bar using nickel-molybdenum (NiMo) catalysts supported on alumina. This step removes compounds to levels below 30 ppm, eliminates and olefin impurities, and saturates aromatics, resulting in a highly stable, low-sulfur product. Additionally, hydrocracking under similar conditions promotes and branching of paraffin chains, improving the fuel's low-temperature properties and combustion characteristics without altering the overall carbon number distribution significantly. Following hydroprocessing, the treated undergoes to isolate the desired C10–C14 cuts, ensuring a narrow range of 185–273°C to minimize volatility variations. Dewaxing is performed via solvent extraction or catalytic methods to reduce content, enhancing fluidity at cryogenic conditions. Aromatics are further limited to below 25% (typically much lower, under 5%) through selective solvent extraction processes, such as using N-methylpyrrolidone or , which preferentially remove unsaturated and aromatic components while preserving paraffinic fractions. These intensive refining steps contribute to RP-1's high cost, making it significantly more expensive than standard Jet A aviation fuel due to the severe hydrotreating requirements and specialized equipment. The narrow compositional tolerances and processing losses result in a low overall yield from crude oil.

Quality Standards and Variations

Quality standards for RP-1 are rigorously defined to ensure batch-to-batch consistency and performance reliability in rocket propulsion systems. The primary U.S. military specification, MIL-DTL-25576F, outlines requirements for rocket-grade kerosene, including Grade RP-1, which mandates compliance with physical, chemical, and thermal properties. Key allowable variations include a density range of 0.799 to 0.815 g/mL at 15°C, a maximum freezing point of -51.1°C (-60°F), and a total sulfur content not exceeding 30 mg/kg (30 ppm), with mercaptan sulfur limited to 3 mg/kg. Olefins are capped at 2.0 vol% to control reactivity and combustion characteristics. These tolerances help maintain uniform ignition, thermal stability, and minimal residue formation across production batches. Testing protocols employ standardized methods to verify these properties. composition and distribution are analyzed using per ASTM D2887, enabling precise typing of the fractions. levels are quantified via (XRF) spectrometry according to ASTM D4294, ensuring detection down to low ppm concentrations. Thermal stability, critical for preventing deposits in engine cooling channels, is evaluated through the Thermal Oxidation Test (JFTOT) as specified in ASTM D3241, which simulates high-temperature flow conditions and measures and deposit formation. Batch under MIL-DTL-25576 requires full adherence to these tests, with 100% compliance verified for procurement by the U.S. Department of Defense. The Russian analog, RG-1, adheres to comparable standards for density (0.82–0.85 g/mL) and low , ensuring in joint programs. Modern variations emphasize enhanced purity for reusable systems. Since the early 2000s, ultra-low formulations (<1 ppm total , achieved via advanced hydrotreating) have been prioritized to improve stability and reduce in regeneratively cooled engines. For instance, grades with below 0.1 ppm exhibit minimal deposit shedding and wall temperature increases during prolonged heating, as demonstrated in heated tube tests at temperatures up to 427°C (800°F). This shift supports engines like SpaceX's , where low- RP-1 (or RP-2 equivalents with <15 ppm ) mitigates and enables multiple firings without performance degradation. composition is further tuned, limiting n-alkanes to approximately 3% or less in some refined batches to optimize minimization during . Recent developments as of 2025 include biofuel-derived RP-1 variants that meet MIL-DTL-25576 specifications while offering up to 4% higher for more sustainable production.

Applications in Propulsion

Engine Compatibility and Usage

RP-1 integrates effectively with liquid rocket engines primarily designed for use with (LOX) as the oxidizer, enabling reliable ignition and stable operation in high-performance systems. In certain engine designs, such as those in the Atlas series, hypergolic ignition is facilitated by injecting a triethylaluminum-triethylborane (TEA-TEB) blend, which spontaneously reacts with LOX to ignite the RP-1 fuel mixture without requiring an external igniter. This approach ensures rapid and consistent startup in LOX/RP-1 engines. Additionally, RP-1 maintains stability in assemblies, supporting impeller tip speeds up to approximately 450 m/s in operational designs like those for LOX/RP-1 engines, where pitchline velocities range from 305 to 457 m/s without inducing excessive vibrations or instability. Feed systems for RP-1 typically employ as a pressurant gas to maintain positive in propellant tanks, preventing boil-off and ensuring steady delivery to the . For instance, in conceptual vehicles like the Delta Clipper, helium is stored at around 5000 psia and regulated to keep RP-1 tank pressures between 47 and 53 psia during flight. RP-1's physical properties, including its density and viscosity, make it compatible with cryogenic environments at -183°C, the of LOX, allowing shared without significant thermal mismatches. Furthermore, RP-1's low at operational temperatures contributes to minimal in pump inducers, enhancing reliability in high-flow feed lines. In combustion chambers, reacts with to produce a high-temperature of approximately 3500 K under stoichiometric conditions, providing the for generation in staged-combustion or gas-generator cycles. The fuel's , with aromatic content limited to less than 25% by volume, significantly reduces formation during and oxidation, resulting in lower carbon deposits compared to higher-aromatic hydrocarbons. This characteristic supports elevated chamber pressures, as demonstrated in the engine, which operates at 26.7 MPa (267 bar) while burning RP-1/, enabling efficient performance without excessive injector erosion. For reusability, RP-1's refined composition promotes low in regenerative cooling channels, where the fuel flows through wall passages to absorb heat before injection, minimizing carbon buildup that could impair multiple firings. In engines like the , this allows the RP-1 to effectively cool the and at temperatures exceeding 3000 K while maintaining channel integrity over repeated uses, aided by the fuel's low and aromatic levels.

Notable Missions and Vehicles

RP-1 has been a cornerstone in numerous landmark rocket missions since the mid-20th century, powering both ballistic missiles and orbital launch vehicles. One of the earliest operational uses occurred with the Thor (IRBM), which debuted in 1957 and employed the Rocketdyne LR79 engine burning RP-1 with (LOX) to achieve its intermediate range capabilities. In the United States, the Atlas rocket series marked another pivotal early application, with its RP-1/ propulsion system enabling early launches such as Discoverer 1 in 1959 from Vandenberg Air Force Base, part of the initial efforts toward polar orbits and demonstrating RP-1's reliability for such missions. This heritage extended to the Apollo program's , where five F-1 engines in the first stage consumed approximately 810,700 liters of RP-1 per launch during missions from 1967 to 1973, supporting 13 crewed flights including the landings. The Soviet Union, and later Russia, similarly relied on RP-1 equivalents like RG-1 kerosene in the R-7 family of launchers, first flown in 1957 to orbit Sputnik 1 and continuously used through the present day in the Soyuz configuration with RD-107 and RD-108 engines for human spaceflight and satellite deployments. The Zenit rocket, introduced in 1985, further showcased RP-1's role in heavy-lift operations via the RD-171 engine, facilitating over 80 launches through the 2010s for commercial and scientific missions before production paused. In modern U.S. programs, SpaceX's and vehicles have extensively utilized RP-1 in their engines since the first orbital flight in 2010, achieving over 550 successful launches by November 2025, including crewed missions to the and prolific constellation deployments. The Delta II rocket, operational from 1989 to 2018 with its RS-27A first-stage engine, also leveraged RP-1/ for over 150 missions, including NASA's Mars rovers and Deep Space probes, bridging legacy systems to contemporary reliability. Post-2020 developments highlight RP-1's enduring relevance amid evolving propulsion trends. India's Space Research Organisation (ISRO) conducted successful hot tests of its 2,000 kN semi-cryogenic engine in 2023 at the Mahendragiri Propulsion Complex, using RP-1/LOX to advance reusable booster technology for future heavy-lift vehicles like the Next Generation Launch Vehicle. Meanwhile, Blue Origin's New Glenn rocket, which debuted on November 13, 2025, marks a shift to methane/LOX in its BE-4 engines, building on RP-1's foundational legacy in U.S. kerosene-fueled rocketry while addressing reusability and performance needs; its first launch successfully deployed NASA's ESCAPADE twin spacecraft to Mars orbit. Globally, RP-1 consumption for rocket propulsion has reached tens of thousands of tons annually, driven primarily by high-cadence launchers like Falcon 9.

Comparisons with Alternatives

Performance and Efficiency Metrics

RP-1, when paired with liquid oxygen (LOX), delivers a vacuum specific impulse (Isp) of approximately 300 seconds, significantly lower than the 450 seconds achieved by liquid hydrogen (LH2)/LOX combinations, reflecting the trade-off between exhaust velocity and propellant density in hydrocarbon-based systems. This lower Isp for RP-1/LOX stems from the heavier molecular weight of kerosene combustion products compared to hydrogen's lighter exhaust, limiting theoretical efficiency but enabling compact, high-thrust designs. To account for volumetric constraints in launch vehicles, density impulse—calculated as Isp multiplied by the of the mixture—favors RP-1/ with a value around 300 s·g/cm³ ( ~1.0 g/cm³ at mixture ratio ~2.3:1 oxidizer-to-fuel), versus approximately 158 s·g/cm³ for LH2/ (bulk density ~0.35 g/cm³ at mixture ratio ~6:1). RP-1's of 43 MJ/kg falls short of LH2's 120 MJ/kg, yet its approximately 3-fold higher compensates by enabling mass fractions exceeding 90% in first-stage boosters, where storability minimizes structural overhead. In the , Δv=Isp⋅g0⋅ln⁡(m0mf)\Delta v = I_{sp} \cdot g_0 \cdot \ln\left(\frac{m_0}{m_f}\right), where g0≈9.81g_0 \approx 9.81 m/s² is , m0m_0 is initial mass, and mfm_f is final mass, RP-1/LOX's balanced Isp and high support high-thrust boosters by maximizing Δv\Delta v through elevated fractions in dense, storable configurations. RP-1/LOX engines exhibit a 10–15% Isp drop from to due to suboptimal expansion in , with values around 300–310 seconds versus 260–280 seconds at . In comparison, /LOX (methalox) alternatives achieve Isp of 310–330 seconds, offering modest efficiency gains over RP-1/LOX while retaining improved over LH2 systems.

Practical Advantages and Limitations

RP-1 offers several practical advantages in rocket propulsion systems, primarily due to its physical properties that simplify ground operations and reduce infrastructure demands. Unlike (LH₂), which requires cryogenic storage at temperatures below 20 K, RP-1 remains liquid at ambient temperatures around 288–310 K, eliminating the need for extensive cryogenic facilities beyond those for (LOX). This stability allows for straightforward handling and long-term storage without significant boil-off losses under normal atmospheric conditions. Additionally, RP-1 exhibits low , with an oral LD50 exceeding 5 g/kg in rats, making it safer for personnel compared to hypergolic fuels like (UDMH), which has an intraperitoneal LD50 of approximately 250 mg/kg and poses severe health risks from even brief exposure. Economically, RP-1 is cost-effective at roughly $2–4 per kg in bulk procurement, far lower than LH₂ at about $5 per kg, contributing to reduced overall launch expenses for expendable vehicles. Despite these benefits, RP-1's combustion characteristics introduce operational limitations, particularly in engine maintenance. When burned with , RP-1 produces higher levels of and carbon deposits () in engine components compared to cleaner fuels like , necessitating more frequent inspections and cleaning to prevent performance degradation or failures in subsequent uses. Although RP-1's low —typically below 1 kPa at —results in negligible boil-off during short-term ground storage, losses can accumulate over extended durations, especially in unpressurized tanks exposed to heat or environments, requiring periodic topping off. In terms of handling, RP-1's non-cryogenic nature enables the use of simpler, less expensive pumps and plumbing systems than those needed for LH₂, which demand specialized materials to withstand extreme cold and prevent embrittlement. However, its relatively higher compared to in certain scenarios increases the risk of boil-off or venting in space conditions without adequate pressurization, potentially leading to mass loss during long missions. Recent trends in design favor methane-LOX combinations for reusable rockets due to methane's reduced , which minimizes engine refurbishment needs and supports rapid turnaround times, as seen in systems like SpaceX's Raptor engines. Nevertheless, RP-1 continues to dominate in cost-sensitive expendable boosters, such as those in the first stage, where its density and affordability outweigh reusability concerns for single-use applications.

Direct Derivatives of RP-1

RP-2 represents a refined variant of RP-1 tailored for U.S. applications, particularly in submarine-launched missiles during the , with specifications limiting total to a maximum of 100 µg/kg and aromatics to 5 vol.% or less to enhance compatibility with naval systems. RG-1 is the Russian equivalent to RP-1, defined under 10227-62, featuring a range of 0.82–0.85 g/mL and elevated paraffin content (approximately 24%) alongside predominantly naphthenic hydrocarbons (about 75%), which supports its use in launch vehicles such as the Soyuz series. T-1 served as an earlier Soviet-grade kerosene fuel, less refined than RG-1 with broader impurity tolerances, and was employed in initial ballistic missiles and launchers like the R-7 before being phased out in the 1970s in favor of more consistent formulations. In the , NASA conducted experimental tests on RP-1 variants, designated RP-1A, incorporating additives to mitigate coking in high-heat engine environments, aiming to reduce deposit formation rates observed at wall temperatures between 600 and 800 K.

Similar Hydrocarbon-Based Fuels

Syntin, a synthetic isoparaffinic hydrocarbon fuel developed in the Soviet Union during the 1960s, served as a high-performance alternative to RP-1 for upper-stage propulsion in launch vehicles such as the Soyuz and Proton rockets. Composed primarily of cyclopropane-based compounds like 1-methyl-1,2-dicyclopropylcyclopropane, syntin offered a specific impulse improvement of approximately 3% over RP-1, achieving around 319 seconds in vacuum conditions, due to its optimized molecular structure for cleaner combustion and higher energy density. It was employed in the Soyuz-U2 variant from 1982 to 1995 but discontinued post-Soviet era owing to high production costs relative to performance gains. JP-8, a jet fuel standard, approximates RP-1 in its base but includes higher aromatic content—up to 25%—along with additives for anti-icing and corrosion inhibition, making it unsuitable for applications where such components lead to carbon deposits and reduced engine reliability. While JP-8 shares similar volatility and density ranges with RP-1, its broader specifications result in inferior thermal stability under the extreme conditions of , as demonstrated in experiments comparing the two fuels' decomposition behaviors. Efforts to blend or adapt JP-8 for propulsion have been limited to ground testing, highlighting its role more as a logistical proxy than a direct substitute. Diesel-kerosene blends have been explored experimentally in low-cost and hobby rocketry since the , leveraging readily available fuels to reduce expenses for amateur launches without the need for specialized refining. These mixtures, often combining diesel's higher with kerosene's lower freezing point, enable simpler engine designs but exhibit variable efficiency and increased formation compared to pure RP-1. Such blends remain niche, primarily for educational or developmental prototypes rather than operational vehicles. Methane, liquefied as part of methalox (methane-liquid oxygen) systems, represents a cryogenic alternative gaining prominence in modern reusable rockets, notably SpaceX's , which achieves a vacuum of approximately 380 seconds with vacuum-optimized Raptor engines—about 20% higher than optimized RP-1 engines—due to its cleaner burn and reduced . This fuel's simplicity in in-situ production on Mars and lower residue buildup enhance reusability, positioning it as a scalable option for high-thrust applications in the . Emerging bio-derived fuels aim to replicate RP-1's properties using sustainable feedstocks like oils and , with research in the 2020s focusing on drop-in analogs that maintain comparable density and ignition characteristics while reducing lifecycle carbon emissions. studies have evaluated -based biofuels for , noting their potential to achieve within 4% of RP-1 in tests, though challenges persist in yield and purification. Similarly, variants from oils have shown promise in hybrid rocket configurations, supporting the transition toward greener alternatives.

Safety and Environmental Aspects

Handling and Safety Measures

RP-1 is classified as a combustible under NFPA standards, specifically a Class II with a flash point between 67°C and 69°C, making it less volatile than highly flammable fuels but still requiring stringent measures. Its autoignition temperature is approximately 210°C, and it can form explosive vapor-air mixtures within concentration limits of 0.7% to 5% by volume, necessitating careful control of ignition sources during operations. To prevent static electricity-induced ignition, all tanks, , and must be electrically grounded, with flanged joints bonded and non-sparking tools used; additionally, tanks are inerted with gas to displace oxygen and minimize explosion risks. In terms of toxicity, RP-1 acts as a mild irritant to the eyes, , and , with low reducing hazards under normal conditions, though prolonged exposure or aspiration can lead to or central nervous system effects. Operators must wear , including chemical-resistant gloves, safety goggles or face shields, flame-retardant clothing, and NIOSH-approved respirators in poorly ventilated areas or during high-exposure tasks. Spills should be contained using non-combustible absorbents such as or , followed by transfer to sealed containers for disposal, while avoiding water dilution that could promote spreading or runoff. Storage of RP-1 occurs in or aluminum tanks designed for and temperature, ensuring compatibility with system components and preventing or over extended periods. These materials are selected for their resistance to RP-1's solvency properties, and in bipropellant applications with , RP-1 tanks can integrate into composite overwrapped pressure vessels to maintain structural integrity under operational stresses. Emergency response protocols for RP-1 align with NFPA 30 guidelines for flammable and combustible liquids, emphasizing diked areas, explosion-proof electrical systems, and readily accessible equipment such as or dry chemical extinguishers to suppress vapors without exacerbating spread. In post-2020 reusable operations, enhanced measures include automated water deluge systems activated during static fires and launches to cool exhaust plumes and mitigate potential fires or structural damage, as demonstrated in SpaceX's pad infrastructure.

Environmental Impacts and Mitigation

The production of RP-1, a highly refined form of derived from crude oil refining processes, generates significant , with traditional methods emitting more than 3 kg of CO2 per liter of fuel, equivalent to approximately 3.7 kg per kg given RP-1's of about 0.81 kg/L. These emissions arise primarily from energy-intensive , hydrotreating, and steps in refineries. Additionally, trace content in RP-1, limited to less than 30 ppm by mass per MIL-P-25576 to prevent and deposits, with modern formulations often achieving lower levels (e.g., <5 ppm) for enhanced reusability, can contribute to formation during refining if not adequately controlled, potentially leading to through atmospheric reactions. During rocket launches, RP-1 with produces approximately 3.16 kg of CO2 per kg of fuel burned, contributing to global accumulation. Incomplete in RP-1/ engines also generates at rates of 30–50 g per kg of fuel, which is injected directly into the and can deplete by up to 4% in the under increased launch scenarios (e.g., 10 Gg/yr emissions). This absorbs solar radiation, warming the by as much as 1.5 K and altering circulation patterns, such as slowing subtropical jet winds by 5 m/s. In the long term, RP-1 exhaust adds to concentrations, with combustion yielding roughly 1.2 kg of H2O per kg of fuel due to oxidation. At high altitudes, this enhances by moistening the , potentially amplifying climate warming through feedback mechanisms like increased and altered dynamics. Spills of RP-1 pose a of contamination, as its low overall (approximately 5–50 mg/L total dissolved hydrocarbons), though key aromatic components like and xylenes have higher solubilities (up to 500 mg/L), limits bulk dissolution but allows dissolved plumes of aromatics to persist in soil and aquifers if not contained. Mitigation efforts in the 2020s include shifts toward "green" variants of RP-1 produced via CO2 capture and renewable , such as Air Company's process, which removes 2.8 kg of CO2 per liter while enabling carbon-negative production. Reusable rocket engines, like those in 's , reduce per-launch environmental waste by minimizing emissions through multiple flights per booster, cutting overall lifecycle impacts by up to 90% compared to expendable systems. Post-2023, the FAA has strengthened regulations via tiered environmental assessments and findings of no significant impact (FONSI), mandating mitigations such as optimized launch corridors to limit ecological disruption from exhaust deposition and in sensitive areas. As of 2025, the FAA continues to require comprehensive environmental assessments for commercial launches, including mitigations for increased RP-1 emissions from high-cadence operations, while companies like explore blends to further reduce lifecycle carbon footprints.

References

  1. https://nvlpubs.nist.gov/nistpubs/Legacy/IR/nistir6646.pdf
  2. https://arc.aiaa.org/doi/pdfplus/10.2514/6.2004-3879
  3. https://ntrs.nasa.gov/api/citations/20140002716/downloads/20140002716.pdf
  4. https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=905293
  5. https://www.spacex.com/vehicles/falcon-9/
  6. https://appel.nasa.gov/wp-content/uploads/2016/01/New_Horizons_RP1_Tank_Case_Study.pdf
  7. https://ntrs.nasa.gov/api/citations/19960045830/downloads/19960045830.pdf
  8. https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=902380
  9. https://patents.google.com/patent/WO2017112717A1/en
  10. https://govtribe.com/file/government-file/rp-attach-2-mil-dtl-25576f-dot-pdf
  11. https://ntrs.nasa.gov/api/citations/20050158764/downloads/20050158764.pdf
  12. https://ntrs.nasa.gov/api/citations/20000065620/downloads/20000065620.pdf
  13. http://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-DTL/MIL-DTL-25576E_16072/
  14. https://rocketprops.readthedocs.io/en/latest/rp1_prop.html
  15. https://ntrs.nasa.gov/api/citations/19770003210/downloads/19770003210.pdf
  16. https://www.mdpi.com/1996-1073/13/22/6055
  17. https://airandspace.si.edu/collection-objects/missile-surface-surface-v-2-alcohol-tank/nasm_A19601994000
  18. https://afdc.energy.gov/fuels/properties
  19. https://www.energy.gov/sites/prod/files/2020/09/f78/beto-sust-aviation-fuel-sep-2020.pdf
  20. https://library.sciencemadness.org/library/books/ignition.pdf
  21. https://apps.dtic.mil/sti/tr/pdf/ADA186752.pdf
  22. https://aoghs.org/products/kerosene-rocket-fuel/
  23. https://www.enginehistory.org/Rockets/RPE03/RPE03.shtml
  24. http://www.astronautix.com/k/kerosene.html
  25. http://www.braeunig.us/space/propel.htm
  26. http://www.astronautix.com/l/loxkerosene.html
  27. https://ntrs.nasa.gov/api/citations/20160008869/downloads/20160008869.pdf
  28. https://forum.kerbalspaceprogram.com/topic/129417-difference-between-rp-1-and-rg-1/
  29. https://patents.google.com/patent/WO2012068369A1/en
  30. https://pubs.acs.org/doi/10.1021/acsomega.0c03259
  31. https://www.aiche.org/resources/publications/cep/2021/october/overview-hydrotreating
  32. https://apps.dtic.mil/sti/pdfs/ADA635643.pdf
  33. https://www.haltermannsolutions.com/tech-talk?id=249256/rocket-fuel-development
  34. https://finance.yahoo.com/news/cleanjoule-celebrates-2024-milestones-accelerating-153000371.html
  35. https://www.sciencedirect.com/topics/physics-and-astronomy/liquid-rocket-propellant
  36. https://ntrs.nasa.gov/api/citations/19740026132/downloads/19740026132.pdf
  37. https://ntrs.nasa.gov/api/citations/19980236000/downloads/19980236000.pdf
  38. https://ntrs.nasa.gov/api/citations/20100035254/downloads/20100035254.pdf
  39. https://ntrs.nasa.gov/api/citations/19740020848/downloads/19740020848.pdf
  40. https://www.sciencedirect.com/science/article/abs/pii/S001793101300906X
  41. https://www.aerospaceguide.net/rocketengines/rd-180.html
  42. https://ntrs.nasa.gov/api/citations/19900016779/downloads/19900016779.pdf
  43. https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/195879/rocketdyne-lr79/
  44. https://ntrs.nasa.gov/api/citations/19940027988/downloads/19940027988.pdf
  45. https://www.nasa.gov/history/afj/ap15fj/01launch_to_earth_orbit.html
  46. https://ntrs.nasa.gov/api/citations/20100015911/downloads/20100015911.pdf
  47. https://sma.nasa.gov/LaunchVehicle/delta.html
  48. https://www.isro.gov.in/First_Hot_Test_SemicryogenicEngine.html
  49. https://www.nasa.gov/wp-content/uploads/2025/09/aeronautics-and-space-report-of-the-president-fy-2024.pdf
  50. https://www.blueorigin.com/news/new-glenn-launches-nasa-escapade-lands-fully-reusable-booster
  51. https://www.bbc.com/future/article/20220713-how-to-make-rocket-launches-less-polluting
  52. https://space.stackexchange.com/questions/59916/why-is-hydrolox-used-for-first-stages
  53. https://space.stackexchange.com/questions/27245/what-are-the-energy-to-mass-ratios-of-some-fuels-oxidizers-when-including-the-o
  54. https://ntrs.nasa.gov/api/citations/20090037584/downloads/20090037584.pdf
  55. https://spacenews.com/atk-successfully-test-fires-3500-lbf-liquid-oxygenmethane-rocket-engine-in-vacuum/
  56. http://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-DTL/download.php?spec=MIL-DTL-25576E.016072.PDF
  57. https://www.scribd.com/document/227551505/1-Kerosene-Fuels-for-Aerospace-Propulsion-Composition-and-Properties
  58. https://www.cia.gov/readingroom/docs/DOC_0000449444.pdf
  59. https://ntrs.nasa.gov/citations/19810021741
  60. https://www.sciencedirect.com/science/article/pii/S2542435122002380
  61. https://ntrs.nasa.gov/api/citations/20140011258/downloads/20140011258.pdf
  62. https://ntrs.nasa.gov/api/citations/20050204031/downloads/20050204031.pdf
  63. https://www.sciencedirect.com/science/article/abs/pii/S0016236122039369
  64. https://www.nasaspaceflight.com/2016/10/its-propulsion-evolution-raptor-engine/
  65. https://www.spacex.com/vehicles/starship/
  66. https://ntrs.nasa.gov/api/citations/20120014219/downloads/20120014219.pdf
  67. https://biodieselmagazine.com/articles/aerospace-industry-continues-biodiesel-related-testing-3296
  68. https://monumentchemical.com/uploads/files/SDS/hf2082_rocket_propellant_rg-1_sds.pdf
  69. https://ntrs.nasa.gov/api/citations/19650018358/downloads/19650018358.pdf
  70. https://apps.dtic.mil/sti/tr/pdf/AD0889763.pdf
  71. https://standards.nasa.gov/sites/default/files/standards/NASA/A/2/nasa-std-871912a_with_change_2.pdf
  72. https://www.faa.gov/sites/faa.gov/files/space/environmental/nepa_docs/SpaceX_Falcon_Program_Final_EA_and_FONSI.pdf
  73. https://fortune.com/2022/12/05/space-travel-is-heating-up-and-so-are-rocket-fuel-emissions-these-companies-are-developing-cleaner-alternatives-to-protect-earth-first/
  74. https://ntrs.nasa.gov/citations/20040140275
  75. https://greenly.earth/en-us/blog/ecology-news/what-is-the-problem-with-kerosene
  76. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2021JD036373
  77. https://everydayastronaut.com/rocket-pollution/
  78. https://medium.com/the-aerospace-corporation/whats-the-impact-of-the-space-industry-on-climate-change-819ab9cfdb01
  79. https://www.enviro.wiki/index.php?title=Petroleum_Hydrocarbons_%28PHCs%29
  80. https://www.kdcresource.com/insights-events/how-can-space-launch-vehicles-be-green/
  81. https://www.faa.gov/space/stakeholder_engagement/spacex_starship
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