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86-538: The Blue Engine 7 is a liquid hydrogen/oxygen dual expander cycle engine for use with the Blue Moon family of lunar landers. The company utilizes additive manufacturing in the development process and it is meant to generate 10,000 lbf (4.5 tf) of thrust, serving as both the ascent and descent engines for Blue Moon. Following the commencement of the Artemis Program the company sought to independently develop

172-527: A fuel cell power system for the Blue Moon lander, in order to enable it to survive the two-week-long lunar night , during which time solar power is unavailable. In October 2019, the National Team of Blue Origin, Lockheed Martin , Northrop Grumman and Draper Laboratory announced that it would collaborate to create a proposal for the " Human Landing System " (HLS) for NASA's Artemis program . Blue Origin

258-451: A thrust-to-weight ratio of 1:1, which is needed to overcome the gravity of the Earth at launch. Over the next twenty-five years, U.S. nuclear thermal rocket designs eventually reached thrust-to-weight ratios of approximately 7:1. This is still a much lower thrust-to-weight ratio than what is achievable with chemical rockets, which have thrust-to-weight ratios on the order of 70:1. Combined with

344-482: A cargo accommodation system for Blue Moon, to be used for large payloads such as surface habitats or lunar rovers . Boeing is to supply a docking system; Draper is to provide guidance, navigation, and control (GNC) technology, and Honeybee Robotics will be responsible for supplying cargo delivery systems. Lockheed Martin is to design and operate a reusable space tug called the Cislunar Transporter as part of

430-485: A consortium of companies to conduct a study on electric thrusters powered by nuclear energy, known as Nuclear Electric Propulsion. The study outlines the roadmap for the launch of a nuclear propulsion demonstrator in 2035. Current solid-core nuclear thermal rocket designs are intended to greatly limit the dispersion and break-up of radioactive fuel elements in the event of a catastrophic failure. As of 2013, an NTR for interplanetary travel from Earth orbit to Mars orbit

516-465: A design contract of US$ 579 million from NASA to advance the design of a human lunar lander for the Artemis program during a 10-month period in 2020–2021. Contracted design work started in 2020 and continued into 2021, when NASA was to evaluate which contractors would be offered contracts for initial demonstration missions and select firms for development and maturation of lunar lander systems. The ILV

602-452: A factor of 2 to 100 compared to conventional nuclear fuels . Fission-fragment rocket using Am was proposed by George Chapline at Lawrence Livermore National Laboratory (LLNL) in 1988, who suggested propulsion based on the direct heating of a propellant gas by fission fragments generated by a fissile material. Ronen et al. demonstrate that Am can maintain sustained nuclear fission as an extremely thin metallic film, less than 1/1000 of

688-495: A fuelled mass of 21,350 kg (47,070 lb). With a payload capacity reaching 3.0 tonnes (3.3 short tons), uses suggested for MK1 include delivery of lunar rovers, as well as a "base station" that would serve as a power and communications outpost for lunar exploration. Blue Moon MK1 will be used as a platform for NASA's Stereo Cameras for Lunar Plume Surface Studies (SCALPSS) payload. Blue Moon's high-thrust engine will be used to study interactions between rocket exhaust plumes and

774-542: A given design, the temperature that can be attained is typically determined by the materials chosen for reactor structures, the nuclear fuel, and the fuel cladding. Erosion is also a concern, especially the loss of fuel and associated releases of radioactivity. Solid core nuclear reactors have been fueled by compounds of uranium that exist in solid phase under the conditions encountered and undergo nuclear fission to release energy. Flight reactors must be lightweight and capable of tolerating extremely high temperatures, as

860-414: A heat source releases thermal energy into a gaseous propellant inside the body of the engine, and a nozzle at one end acts as a very simple heat engine: it allows the propellant to expand away from the vehicle, carrying momentum with it and converting thermal energy to coherent kinetic energy. The specific impulse (Isp) of the engine is set by the speed of the exhaust stream. That, in turn, varies as

946-677: A higher effective exhaust velocity and is expected to double or triple payload capacity compared to chemical propellants that store energy internally. NTRs have been proposed as a spacecraft propulsion technology, with the earliest ground tests occurring in 1955. The United States maintained an NTR development program through 1973 when it was shut down for various reasons, including to focus on Space Shuttle development. Although more than ten reactors of varying power output have been built and tested, as of 2024 , no nuclear thermal rocket has flown. Whereas all early applications for nuclear thermal rocket propulsion used fission processes, research in

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1032-537: A larger design in the Space Thermal Nuclear Propulsion (STNP) program. Advances in high-temperature metals, computer modeling, and nuclear engineering, in general, resulted in dramatically improved performance. While the NERVA engine was projected to weigh about 6,803 kilograms (14,998 lb), the final STNP offered just over 1/3 the thrust from an engine of only 1,650 kilograms (3,640 lb) by improving

1118-571: A lunar lander, the 'MK1' and accompanying engine. The BE-7 test phase began in 2019 with additional hot fire testing in 2020 at the Marshall Space Flight Center . Following selection for NASA's second Human Landing System, which Blue Origin calls 'MK2', the company announced that the BE-7 engine will be used for both landers. A demonstration flight of the MK1, planned for 2025 is on track and will debut

1204-453: A marginally reduced fuel cost. Yet another mark in favor of hydrogen is that at low pressures it begins to dissociate at about 1500 K, and at high pressures around 3000 K. This lowers the mass of the exhaust species, increasing I sp . Early publications were doubtful of space applications for nuclear engines. In 1947, a complete nuclear reactor was so heavy that solid core nuclear thermal engines would be entirely unable to achieve

1290-524: A millimeter thick. Am requires only 1% of the mass of U or Pu to reach its critical state. Ronen's group at the Ben-Gurion University of the Negev further showed that nuclear fuel based on Am could speed space vehicles from Earth to Mars in as little as two weeks. The Am as a nuclear fuel is derived from the fact that it has the highest thermal fission cross section (thousands of barns ), about 10x

1376-580: A mockup of the Blue Moon lander at the Washington D.C. Convention Center and released specification details for the autonomous lander planned to land up to 6.5 t (14,000 lb) on the Moon, to be powered by the newly unveiled BE-7 . Blue Moon-derived concepts aimed at carrying passengers to the Moon were also exhibited. That July, NASA announced that Glenn Research Center and Johnson Space Center would engage in an partnership with Blue Origin to develop

1462-527: A novel type of nuclear rocket . Since the thermal absorption cross section of Am is very high, the best way to obtain Am is by the capture of fast or epithermal neutrons in Americium-241 irradiated in a fast reactor . However, fast spectrum reactors are not readily available. Detailed analysis of Am breeding in existing pressurized water reactors (PWRs) was provided. Proliferation resistance of Am

1548-554: A nuclear space engine, as well as previous tests of fuel rods and ion engines . Development of solid core NTRs started in 1955 under the Atomic Energy Commission (AEC) as Project Rover and ran to 1973. Work on a suitable reactor was conducted at Los Alamos National Laboratory and Area 25 (Nevada National Security Site) in the Nevada Test Site . Four basic designs came from this project: KIWI, Phoebus, Pewee, and

1634-599: A propellant gas. Project 242 studied the application of this propulsion system to a crewed mission to Mars. Preliminary results were very satisfactory, and it has been observed that a propulsion system with these characteristics could make the mission feasible. Another study focused on the production of Am in conventional thermal nuclear reactors. In 2022, the European Space Agency launched an initiative called "Preliminary European Reckon on Nuclear Electric Propulsion for Space Applications" (RocketRoll) and commissioned

1720-592: A proposal for a human lander bid, but was not chosen for the Artemis HLS program. The human lander, referred to as MK2, was chosen by NASA as the winner of the Sustaining Lunar Development Human Landing System contract in May 2023. It is the second human lunar lander under contract by NASA for the Artemis HLS program, alongside Starship HLS . It is intended to carry up to 4 astronauts to

1806-434: A series of groundbreaking scientific papers that considered how nuclear technology might be applied to interplanetary travel . The papers examined both nuclear-thermal and nuclear-electric propulsion. Through Project Rover , Los Alamos National Laboratory began developing nuclear thermal engines as soon as 1955 and tested the world's first experimental nuclear rocket engine, KIWI-A , in 1959. This work at Los Alamos

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1892-439: A set temperature is reached, the reactor is quickly turned off again. During these pulses, the power being produced is far greater than the same sized reactor could produce continually. The key to this approach is that while the total amount of fuel that can be pumped through the reactor during these brief pulses is small, the resulting efficiency of these pulses is much higher. Generally, the designs would not be operated solely in

1978-467: A single piece. The regeneratively-cooled nozzle is composed of a nickel super-alloy jacket, vacuum-brazed onto a copper liner, and hydraulically formed into the nozzle's bell shape. Design work on a Blue Origin robotic lunar lander began in 2016. The lander platform was first publicly revealed in March 2017, featuring a lunar-surface-delivered payload capacity of 4,500 kg (10,000 lb). At that time

2064-456: A system will enable the spacecraft to loiter in orbit or on the surface of the Moon, potentially allowing a permanent lunar presence or supporting nuclear thermal propulsion . Blue Origin is to lead the development of the lander, which is designed to fit in the 7 m (23 ft) payload fairing of the New Glenn launch vehicle in order to launch aboard the rocket. Astrobotic is to provide

2150-609: A theoretical maximum specific impulse that is 3 to 4.5 times greater than those of chemical rockets. In 1944, Stanisław Ulam and Frederic de Hoffmann contemplated the idea of controlling the power of nuclear explosions to launch space vehicles. After World War II, the U.S. military started the development of intercontinental ballistic missiles (ICBM) based on the German V-2 rocket designs. Some large rockets were designed to carry nuclear warheads with nuclear-powered propulsion engines. As early as 1946, secret reports were prepared for

2236-598: A time, starting with the NASA Artemis 5 mission, set for 2030. The Blue Moon lander is to be capable of conducting crewed lunar landings lasting up to 30 days, pending an uncrewed demonstration flight scheduled for 2027. This uncrewed flight is to be a full demonstration of the HLS portion of the Artemis 5 mission, including the lander's life support systems, that would see the lander returning to near-rectilinear halo orbit after departing

2322-489: A way to gain experience with lunar landings and to support technology development, MK 1 is also marketed independently of MK2. The lander has been proposed for a number of projected roles; an initial goal was a lunar south pole landing, where it was proposed that a series of landings could be used to deliver the infrastructure for a Moon base. Blue Moon formed the basis of part of the Integrated Lander Vehicle ,

2408-508: Is being studied at Marshall Space Flight Center with Glenn Research Center . In historical ground testing, NTRs proved to be at least twice as efficient as the most advanced chemical engines, which would allow for quicker transfer time and increased cargo capacity. The shorter flight duration, estimated at 3–4 months with NTR engines, compared to 6–9 months using chemical engines, would reduce crew exposure to potentially harmful and difficult to shield cosmic rays . NTR engines, such as

2494-436: Is designed to produce a maximum of 44 kN (10,000 lbf) of thrust and to throttle down to produce as little as 8.9 kN (2,000 lbf) of thrust. In addition to this "deep throttle" capability, it is also meant to be highly efficient, with high specific impulse, and to be capable of restarting multiple times. The BE-7 is additively manufactured , with components such as the injector being additively manufactured in

2580-503: Is proposed to operate at temperatures above the melting point of solid nuclear fuel and cladding, with the maximum operating temperature of the engine instead of being determined by the reactor pressure vessel and neutron reflector material. The higher operating temperatures would be expected to deliver specific impulse performance on the order of 1300 to 1500 seconds (12.8-14.8 kN·s/kg). A liquid-core reactor would be extremely difficult to build with current technology. One major issue

2666-415: Is that the reaction time of the nuclear fuel is much longer than the heating time of the working fluid. If the nuclear fuel and working fluid are not physically separated, this means that the fuel must be trapped inside the engine while the working fluid is allowed to easily exit through the nozzle. One possible solution is to rotate the fuel/fluid mixture at very high speeds to force the higher-density fuel to

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2752-400: Is then cooled, typically using water. In the case of a nuclear engine, the water is replaced by hydrogen, but the concept is otherwise similar. Pulsed reactors attempt to transfer the energy directly from the neutrons to the working mass, allowing the exhaust to reach temperatures far beyond the melting point of the reactor core. As specific impulse varies directly with temperature, capturing

2838-471: Is to dock to and fuel the Blue Moon lander. Lockheed Martin has suggested that the Cislunar Transporter could also be used to service other customers. The same zero-boil-off system intended for Blue Moon will also be present on the Transporter. Both variants of Blue Moon, as well as the Cislunar Transporter, are to be powered by the BE-7 liquid oxygen/liquid hydrogen engine currently under development. MK1

2924-421: Is to use a single engine, whereas the other spacecraft are to each use three. The BE-7 burns its propellants, chosen in part because they can be produced on the surface of the Moon from lunar ice , in the dual expander cycle , wherein each propellant flows through the engine, gaining heat energy, which is then used to spin turbines, providing energy to pump propellant into the combustion chamber. The BE-7 engine

3010-688: The Applied Physics Laboratory published their research on nuclear power propulsion and their report was eventually classified. In May 1947, American-educated Chinese scientist Qian Xuesen presented his research on "thermal jets" powered by a porous graphite-moderated nuclear reactor at the Nuclear Science and Engineering Seminars LIV organized by the Massachusetts Institute of Technology . In 1948 and 1949, physicist Leslie Shepherd and rocket scientist Val Cleaver produced

3096-510: The U.S. Air Force , as part of the NEPA project , by North American Aviation and Douglas Aircraft Company 's Project Rand . These groundbreaking reports identified a reactor engine in which a working fluid of low molecular weight is heated using a nuclear reactor as the most promising form of nuclear propulsion but identified many technical issues that needed to be resolved. In January 1947, not aware of this classified research, engineers of

3182-426: The "open cycle", the losses of nuclear fuel would be difficult to control, which has led to studies of the "closed cycle" or nuclear lightbulb engine, where the gaseous nuclear fuel is contained in a super-high-temperature quartz container, over which the hydrogen flows. The closed-cycle engine has much more in common with the solid-core design, but this time is limited by the critical temperature of quartz instead of

3268-729: The 2010s has moved to fusion approaches. The Direct Fusion Drive project at the Princeton Plasma Physics Laboratory is one such example, although "energy-positive fusion has remained elusive". In 2019, the U.S. Congress approved US$ 125 million in development funding for nuclear thermal propulsion rockets. In May 2022 DARPA issued an RFP for the next phase of their Demonstration Rocket for Agile Cislunar Operations (DRACO) nuclear thermal engine program. This follows on their selection, in 2021, of an early engine design by General Atomics and two spacecraft concepts from Blue Origin and Lockheed Martin . The next phases of

3354-487: The BE-7 engine. In 2024, the company announced vacuum cell testing was being conducted on the engine at the Edwards Air Force Base . The BE-7 utilizes liquid hydrogen and liquid oxygen propellants in a dual expander cycle generating up to 10,000 pounds-force of thrust which can be throttled to 2,000 pounds-force. The company hopes that the propellants can, in the future, utilize ISRU and be produced from ice in

3440-459: The Blue Moon architecture. The Cislunar Transporter consists of two parts, a tug, with 3 BE-7 engines, and a tanker, which are each to be launched on a New Glenn carrier rocket before docking together to form a single vehicle. After these components are assembled, the vehicle is then to be fueled by New Glenn upper stages transferring liquid oxygen and liquid hydrogen propellants. The transporter will then travel to near-rectilinear halo orbit, where it

3526-460: The Cislunar Transporter are to be powered by three BE-7 engines burning liquid hydrogen fuel and liquid oxygen oxidizer. They are intended to make use of new cryogenic fluid management technologies under development, including those to enable long-term on-orbit storage of their cryogenic propellants . Several spacecraft designs are included in the Blue Moon program. These include the Mark 1 lander,

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3612-603: The Earth's atmosphere and perhaps even magnetosphere . The final fission classification is the gas-core engine . This is a modification to the liquid-core design which uses rapid circulation of the fluid to create a toroidal pocket of gaseous uranium fuel in the middle of the reactor, surrounded by hydrogen. In this case, the fuel does not touch the reactor wall at all, so temperatures could reach several tens of thousands of degrees, which would allow specific impulses of 3000 to 5000 seconds (30 to 50 kN·s/kg). In this basic design,

3698-466: The I sp to between 930 and 1000 seconds. KIWI was the first to be fired, starting in July 1959 with KIWI 1. The reactor was not intended for flight and was named after the flightless bird , Kiwi. The core was simply a stack of uncoated uranium oxide plates onto which the hydrogen was dumped. The thermal output of 70  MW at an exhaust temperature of 2683 K was generated. Two additional tests of

3784-434: The Mark 2, and the Cislunar Transporter. Additionally, the BE-7 liquid rocket engine is under development and testing, and is intended to be used on each of these spacecraft. Blue Moon MK1, powered by a single BE-7 engine, is an autonomous lunar lander planned to be able to deliver and support cargo on the surface of the Moon. The MK1 spacecraft is 8.05 m (26.4 ft) tall and 3.08 m (10.1 ft) in diameter, with

3870-562: The Nuclear Furnace. Progressively higher power densities culminated in the Pewee. Tests of the improved Pewee 2 design were canceled in 1970 in favor of the lower-cost Nuclear Furnace (NF-1), and the U.S. nuclear rocket program officially ended in the spring of 1973. During this program, the NERVA accumulated over 2 hours of run time, including 28 minutes at full power. The SNPO considered NERVA to be

3956-570: The Nuclear Furnace. Twenty individual engines were tested, with a total of over 17 hours of engine run time. When NASA was formed in 1958, it was given authority over all non-nuclear aspects of the Rover program. To enable cooperation with the AEC and keep classified information compartmentalized, the Space Nuclear Propulsion Office (SNPO) was formed at the same time. The 1961 NERVA program

4042-412: The Pewee was also built. It was fired several times at 500 MW to test coatings made of zirconium carbide (instead of niobium carbide ) but Pewee also increased the power density of the system. A water-cooled system is known as NF-1 (for Nuclear Furnace ) used Pewee 2's fuel elements for future materials testing, showing a factor of 3 reductions in fuel corrosion still further. Pewee 2 was never tested on

4128-589: The Shuttle cargo bay. The design provided 73 kN of thrust and operated at a specific impulse of 875 seconds (8.58 kN·s/kg), and it was planned to increase this to 975 seconds, achieving a mass fraction of about 0.74, compared with 0.86 for the Space Shuttle main engine (SSME). A related design that saw some work, but never made it to the prototype stage, was Dumbo. Dumbo was similar to KIWI/NERVA in concept, but used more advanced construction techniques to lower

4214-484: The U.S. Rover program intentionally modified a Kiwi reactor (KIWI-TNT) to go prompt critical, resulting in immediate destruction of the reactor pressure vessel, nozzle, and fuel assemblies. Intended to simulate a worst-case scenario of a fall from altitude into the ocean, such as might occur in a booster failure after launch, the resulting release of radiation would have caused fatalities out to 200 m (600 ft) and injuries out to 600 m (2,000 ft). The reactor

4300-436: The basic concept, A1 and A3, added coatings to the plates to test fuel rod concepts. The KIWI B series was fueled by tiny uranium dioxide (UO 2 ) spheres embedded in a low- boron graphite matrix and coated with niobium carbide . Nineteen holes ran the length of the bundles, through which the liquid hydrogen flowed. On the initial firings, immense heat and vibration cracked the fuel bundles. The graphite materials used in

4386-435: The energy of the relativistic neutrons allows for a dramatic increase in performance. To do this, pulsed reactors operate in a series of brief pulses rather than the continual chain reaction of a conventional reactor. The reactor is normally off, allowing it to cool. It is then turned on, along with the cooling system or fuel flow, operating at a very high power level. At this level the core rapidly begins to heat up, so once

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4472-500: The first lunar landing mission was projected to take place in 2020. In April 2017, Blue Origin president Rob Meyerson stated that the lander could be launched by multiple launch vehicles, including Blue Origin's New Glenn , Atlas V , NASA's Space Launch System , or the Vulcan launch vehicle. In a May 2018 interview, Blue Origin's CEO Jeff Bezos indicated that Blue Origin would build Blue Moon on its own, with private funding, but that

4558-426: The fuel and cladding. Although less efficient than the open-cycle design, the closed-cycle design is expected to deliver a specific impulse of about 1500 to 2000 seconds (15 to 20 kN·s/kg). The Soviet RD-0410 went through a series of tests at the nuclear test site near Semipalatinsk Test Site . In October 2018, Russia's Keldysh Research Center confirmed a successful ground test of waste heat radiators for

4644-416: The large tanks necessary for liquid hydrogen storage, this means that solid core nuclear thermal engines are best suited for use in orbit outside Earth's gravity well , not to mention avoiding the radioactive contamination that would result from atmospheric use (if an "open-cycle" design was used, as opposed to a lower-performance "closed cycle" design where no radioactive material was allowed to escape with

4730-501: The last technology development reactor required to proceed to flight prototypes. Several other solid-core engines have also been studied to some degree. The Small Nuclear Rocket Engine, or SNRE, was designed at the Los Alamos National Laboratory (LANL) for upper stage use, both on uncrewed launchers and the Space Shuttle . It featured a split-nozzle that could be rotated to the side, allowing it to take up less room in

4816-402: The lunar surface for up to 30 days in a fully reusable configuration, with a cargo variant also planned. The lander is designed to be paired with a space tug called the Cislunar Transporter, to be built by Lockheed Martin. The Cislunar Transporter is launched in two parts, a tug and a tanker, to low Earth orbit before refueling Blue Moon in a lunar near-rectilinear halo orbit . Both MK2 and

4902-551: The lunar surface. A variant of the lander designed to carry cargo is also planned, capable of carrying a payload of up to 20 t (44,000 lb) to the surface of the Moon in a reusable configuration or 30 t (66,000 lb) in a one-way mission. A technology critical for the operation of Blue Moon, being developed by Blue Origin, is a solar-powered propellant boiloff mitigation mechanism intended to enable long-term storage of liquid oxygen and liquid hydrogen at temperatures as low as 20 K (−253 °C; −424 °F). Such

4988-416: The lunar surface. Uncrewed technology demonstration and risk reduction missions using MK1 are to be performed as early as 2024 and 2025. As of 2023, these missions are scheduled to take place no later than 2026. The flight computers, avionics, reaction control system, and power system of MK1 are to be in common with those used on MK2. Blue Moon MK2 is to carry 4 astronauts to the Moon, for up to 30 days at

5074-399: The next highest cross section across all known isotopes. The Am is fissile (because it has an odd number of neutrons ) and has a low critical mass , comparable to that of Pu . It has a very high cross section for fission, and if in a nuclear reactor is destroyed relatively quickly. Another report claims that Am can sustain a chain reaction even as a thin film, and could be used for

5160-574: The only coolant available is the working fluid/propellant. A nuclear solid core engine is the simplest design to construct and is the concept used on all tested NTRs. Using hydrogen as a propellant, a solid core design would typically deliver specific impulses (I sp ) on the order of 850 to 1000 seconds, which is about twice that of liquid hydrogen - oxygen designs such as the Space Shuttle main engine . Other propellants have also been proposed, such as ammonia, water, or LOX , but these propellants would provide reduced exhaust velocity and performance at

5246-473: The original HLS contract. Nuclear thermal rocket A nuclear thermal rocket ( NTR ) is a type of thermal rocket where the heat from a nuclear reaction replaces the chemical energy of the propellants in a chemical rocket . In an NTR, a working fluid , usually liquid hydrogen , is heated to a high temperature in a nuclear reactor and then expands through a rocket nozzle to create thrust . The external nuclear heat source theoretically allows

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5332-512: The outside, but this would expose the reactor pressure vessel to the maximum operating temperature while adding mass, complexity, and moving parts. An alternative liquid-core design is the nuclear salt-water rocket . In this design, water is the working fluid and also serves as the neutron moderator . Nuclear fuel is not retained, which drastically simplifies the design. However, the rocket would discharge massive quantities of extremely radioactive waste and could only be safely operated well outside

5418-477: The polar regions of the moon. It will also be used to power the transfer element, the Cislunar Transporter in development by Lockheed Martin . Blue Moon (spacecraft) Development of the smaller, uncrewed lander began in 2016 and was publicly revealed in 2017. It is planned to be capable of delivering up to 3.0 tonnes (3.3 short tons) of payload to the surface of the Moon. Originally envisioned as

5504-547: The program will focus on the design, development, fabrication, and assembly of a nuclear thermal rocket engine. In July 2023, Lockheed Martin was awarded the contract to build the spacecraft and BWX Technologies ( BWXT ) will develop the nuclear reactor. A launch is expected in 2027. Nuclear-powered thermal rockets are more effective than chemical thermal rockets, primarily because they can use low-molecular-mass propellants such as hydrogen. As thermal rockets, nuclear thermal rockets work almost exactly like chemical rockets :

5590-476: The project's pace would increase should governmental space agency partner with the company. Bezos mentioned Space Directive 1 , which oriented NASA towards pursuing lunar missions, and his support for the Moon Village concept, "a proposal promoted by European Space Agency head Jan Woerner for cooperation among countries and companies to cooperate... on lunar capabilities". In May 2019, Blue Origin unveiled

5676-490: The pulsed mode but could vary their duty cycle depending on the need. For instance, during a high-thrust phase of flight, like exiting a low earth orbit , the engine could operate continually and provide an Isp similar to that of traditional solid-core design. But during a long-duration cruise, the engine would switch to pulsed mode to make better use of its fuel. Liquid core nuclear engines are fueled by compounds of fissionable elements in liquid phase . A liquid-core engine

5762-619: The reactor's construction were resistant to high temperatures but eroded under the stream of superheated hydrogen, a reducing agent . The fuel species was later switched to uranium carbide , with the last engine run in 1964. The fuel bundle erosion and cracking problems were improved but never completely solved, despite promising materials work at the Argonne National Laboratory . NERVA NRX (Nuclear Rocket Experimental), started testing in September 1964. The final engine in this series

5848-422: The rocket propellant. ) One way to increase the working temperature of the reactor is to change the nuclear fuel elements. This is the basis of the particle-bed reactor, which is fueled by several (typically spherical) elements that "float" inside the hydrogen working fluid. Spinning the entire engine could prevent the fuel element from being ejected out the nozzle. This design is thought to be capable of increasing

5934-525: The second lander procured under the Artemis HLS program, under Appendix P of the NextSTEP-2 contracting structure, also known as Sustaining Lunar Development. Blue Moon was proposed by a renewed National Team, with slightly different composition than that which had developed the Integrated Lander Vehicle. The total value of the contract was approximately US$ 3.4 billion; Blue Origin stated that it

6020-480: The specific impulse to about 1000 seconds (9.8 kN·s/kg) at the cost of increased complexity. Such a design could share design elements with a pebble-bed reactor , several of which are currently generating electricity. From 1987 through 1991, the Strategic Defense Initiative (SDI) Office funded Project Timberwind , a non-rotating nuclear thermal rocket based on particle bed technology. The project

6106-681: The square root of the kinetic energy loaded on each unit mass of propellant. The kinetic energy per molecule of propellant is determined by the temperature of the heat source (whether it be a nuclear reactor or a chemical reaction ). At any particular temperature, lightweight propellant molecules carry just as much kinetic energy as heavier propellant molecules and therefore have more kinetic energy per unit mass. This makes low-molecular-mass propellants more effective than high-molecular-mass propellants. Because chemical rockets and nuclear rockets are made from refractory solid materials, they are both limited to operate below 3,000 °C (5,000 °F), by

6192-454: The stand and became the basis for current NTR designs being researched at NASA 's Glenn Research Center and Marshall Space flight Center. The NERVA/Rover project was eventually canceled in 1972 with the general wind-down of NASA in the post- Apollo era. Without a human mission to Mars , the need for a nuclear thermal rocket is unclear. Another problem would be public concerns about safety and radioactive contamination . In January 1965,

6278-480: The strength characteristics of high-temperature metals. Chemical rockets use the most readily available propellant, which is waste products from the chemical reactions producing their heat energy. Most liquid-fueled chemical rockets use either hydrogen or hydrocarbon combustion, and the propellant is therefore mainly water (molecular mass 18) and carbon dioxide (molecular mass 44). Nuclear thermal rockets using gaseous hydrogen propellant (molecular mass 2) therefore have

6364-420: The type of reactor, ranging from a relatively simple solid reactor up to the much more difficult to construct but theoretically more efficient gas core reactor. As with all thermal rocket designs, the specific impulse produced is proportional to the square root of the temperature to which the working fluid (reaction mass) is heated. To extract maximum efficiency, the temperature must be as high as possible. For

6450-405: The weight of the reactor. The Dumbo reactor consisted of several large barrel-like tubes, which were in turn constructed of stacked plates of corrugated material. The corrugations were lined up so that the resulting stack had channels running from the inside to the outside. Some of these channels were filled with uranium fuel, others with a moderator, and some were left open as a gas channel. Hydrogen

6536-684: Was aimed at landing NASA astronauts on the Moon as early as 2024, following an uncrewed demonstrator that was to land on the Moon as early as 2023. The ILV descent element was a variant of the Blue Moon lunar lander that Blue Origin had been working on for nearly three years by early 2020. At the end of the year-long program, the ILV was not chosen for further development, NASA having selected instead SpaceX's Starship HLS bid. Although NASA had previously stated it wished to procure multiple Human Landing Systems, it only selected one lander design, citing budgetary limitations. In May 2023, NASA selected Blue Moon as

6622-407: Was canceled before testing. In a conventional solid core design, the maximum exhaust temperature of the working mass is that of the reactor, and in practice, lower than that. That temperature represents an energy far below that of the individual neutrons released by the fission reactions. Their energy is spread out through the reactor mass, causing it to thermalize. In power plant designs, the core

6708-480: Was intended to lead to the entry of nuclear thermal rocket engines into space exploration. Unlike the AEC work, which was intended to study the reactor design itself, NERVA's goal was to produce a real engine that could be deployed on space missions. The 334 kN (75,000 lb f ) thrust baseline NERVA design was based on the KIWI B4 series. Tested engines included Kiwi, Phoebus, NRX/EST, NRX/XE, Pewee, Pewee 2, and

6794-649: Was judged sufficient for space missions by SNPO. Building on the KIWI series, the Phoebus series were much larger reactors. The first 1A test in June 1965 ran for over 10 minutes at 1090 MW and an exhaust temperature of 2370 K. The B run in February 1967 improved this to 1500 MW for 30 minutes. The final 2A test in June 1968 ran for over 12 minutes at 4000 MW, at the time the most powerful nuclear reactor ever built. A smaller version of KIWI,

6880-569: Was positioned on a railroad car in the Jackass Flats area of the Nevada Test Site . As of January 2012, the propulsion group for Project Icarus was studying an NTR propulsion system, but has seen little activity since 2019. In 1987, Ronen & Leibson published a study on applications of Am (one of the isotopes of americium ) as nuclear fuel to space nuclear reactors , noting its extremely high thermal cross section and energy density . Nuclear systems powered by Am require less fuel by

6966-477: Was providing at least that amount of funding itself to the Blue Moon project. Blue Moon had successfully competed with the Dynetics ALPACA for the contract; NASA stated that the lower cost and technical strengths of Blue Moon led to its selection. Appendix P had been open to bidding, with the exception of SpaceX, which had received a similar contract under Option B of Appendix H of NextSTEP-2, as provided for by

7052-402: Was pumped into the middle of the tube and would be heated by the fuel as it traveled through the channels as it worked its way to the outside. The resulting system was lighter than a conventional design for any particular amount of fuel. Between 1987 and 1991, an advanced engine design was studied under Project Timberwind , under the Strategic Defense Initiative , which was later expanded into

7138-479: Was reported by the Karlsruhe Institute of Technology 2008 study. In 2000, Carlo Rubbia at CERN further extended the work by Ronen and Chapline on a Fission-fragment rocket using Am as a fuel. Project 242 based on Rubbia design studied a concept of Am based Thin-Film Fission Fragment Heated NTR by using a direct conversion of the kinetic energy of fission fragments into increasing of enthalpy of

7224-628: Was the XE, designed with flight representative hardware and fired into a low-pressure chamber to simulate a vacuum. SNPO fired NERVA NRX/XE twenty-eight times in March 1968. The series all generated 1100 MW, and many of the tests concluded only when the test-stand ran out of hydrogen propellant. NERVA NRX/XE produced the baseline 334 kN (75,000 lb f ) thrust that Marshall Space Flight Center required in Mars mission plans. The last NRX firing lost 17 kg (38 lb) of nuclear fuel in 2 hours of testing, which

7310-480: Was then continued through the NASA's NERVA program (1961–1973). NERVA achieved many successes and improved upon the early prototypes to create powerful engines that were several times more efficient than chemical counterparts. However, the program was cancelled in 1973 due to budget constraints. To date no nuclear thermal propulsion system has ever been implemented in space. A nuclear thermal rocket can be categorized by

7396-463: Was to serve as the primary contractor, with a variant of its Blue Moon Lunar Lander serving as the descent stage. Lockheed Martin would build the ascent stage, in part based on its Orion crew capsule. Northrop Grumman would build a transfer stage based on its Cygnus spacecraft . The lander was projected to launch on the Blue Origin New Glenn launch vehicle. In April 2020, Blue Origin won

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