Lunar Gateway
The Lunar Gateway, or simply Gateway, is a planned space station to be assembled in orbit around the Moon. Developed as part of NASA’s Artemis program, the Gateway is intended to serve as a communications hub, science laboratory, and habitation module for supporting both crewed and robotic lunar exploration. It is designed to be the first space station constructed beyond low [Earth orbit] and as a staging point for future human missions to Mars.
The project is led by NASA in collaboration with international partners, including the European Space Agency, the Japan Aerospace Exploration Agency, the Canadian Space Agency, and the Mohammed Bin Rashid Space Centre, with additional participation from commercial partners.
In July 2025, the passage of the One Big Beautiful Bill Act allocated $2.6 billion to fund the program through FY 2032.
Overview
The Gateway is expected to serve a central role in the Artemis program beginning in the latter half of the 2020s: providing docking ports and communications relays for Orion and lunar landers like Starship HLS, staging for surface missions to the lunar south polar region, and as a platform for crewed transfer. It will also be used to evaluate concepts needed for long-duration deep-space missions.Scientific research to be studied on the Gateway are expected to include planetary science, astrophysics, Earth observation, space biology, heliophysics, and studies of human health and performance in deep-space environments.
Construction of the station's initial elements, including the Power and Propulsion Element and the Habitation and Logistics Outpost , began in the early 2020s. PPE and HALO are planned to launch together on a Falcon Heavy no earlier than 2027, with crewed assembly and first crewed visits expected to be part of Artemis IV, currently targeted for no earlier than September 2028.
Name
The station was initially announced as the Deep Space Gateway in 2017. NASA’s FY 2019 budget request renamed the station as Lunar Orbital Platform-Gateway .In November 2019, NASA officially designated the station as Gateway. The station’s logo was inspired by the American landmark Gateway Arch in St. Louis.
History
Background
The Apollo Command and Service Module was the first crewed lunar orbiting spacecraft performing dockings and crew transfers with another spacecraft, the Apollo Lunar Module. Lunar bases, like the first Tranquility Base as well as concepts for lunar bases have been the main focus of human presence at the Moon.Studies
An earlier NASA proposal for a cislunar station had been made public in 2012 and was dubbed the Deep Space Habitat. That proposal led to funding in 2015 under the NextSTEP program to study the requirements of deep space habitats. In February 2018, it was announced that the NextSTEP studies and other ISS partner studies would help to guide the capabilities required of the Gateway's habitation modules. The solar electric Power and Propulsion Element of the Gateway was originally a part of the now-canceled Asteroid Redirect Mission.On 7 November 2017, NASA asked the global science community to submit concepts for scientific studies that could take advantage of the Deep Space Gateway's location in cislunar space. The Deep Space Gateway Concept Science Workshop was held in Denver, Colorado, from 27 February to 1 March 2018. This three-day conference was a workshop where 196 presentations were given for possible scientific studies that could be advanced through the use of the Gateway.
In 2018, NASA initiated the Revolutionary Aerospace Systems Concepts Academic Linkage competition for universities to develop concepts and capabilities for the Gateway. The competitors were asked to employ original engineering and analysis in one of four areas: "Gateway Uncrewed Utilization and Operations", "Gateway-Based Human Lunar Surface Access", "Gateway Logistics as a Science Platform", and "Design of a Gateway-Based Cislunar Tug". Teams of undergraduate and graduate students were asked to submit a response by 17 January 2019 addressing one of these four themes. NASA selected 20 teams to continue developing proposed concepts. Fourteen of the teams presented their projects in person in June 2019 at the RASC-AL Forum in Cocoa Beach, Florida, receiving a US$6,000 stipend to participate in the Forum. The "Lunar Exploration and Access to Polar Regions", from the University of Puerto Rico at Mayagüez, was the winning concept.
On May 2, 2018, NASA stated the International Space Exploration Coordination Group, a non-binding coordination forum comprising 14 worldwide space agencies, identified the Gateway as a critical component in expanding human presence to the Moon, Mars, and deeper into the Solar System.
International participants
On 27 September 2017, an informal joint statement on cooperation regarding the program between NASA and Russia's Roscosmos was announced. However, in October 2020 Dmitry Rogozin, director general of Roscosmos, said that the program is too "U.S.-centric" for Roscosmos to participate, and in January 2021, Roscosmos announced that it would not participate in the program.As of January 2024, the Canadian Space Agency, the European Space Agency, Japan Aerospace Exploration Agency and Mohammed Bin Rashid Space Centre plan to participate in the Gateway project, each contributing a robotic arm, refuelling and communications hardware, habitation and research capacity and an airlock module. These international elements are intended to launch after the initial NASA PPE and HALO elements are placed into lunar orbit with some co-manifested with Artemis missions.
Power and propulsion
On 1 November 2017, NASA commissioned five studies lasting four months into affordable ways to develop the Power and Propulsion Element, leveraging private companies' plans. These studies had a combined budget of US$2.4 million. The companies performing the PPE studies were Boeing, Lockheed Martin, Orbital ATK, Sierra Nevada, and Space Systems/Loral. These awards are in addition to the ongoing set of NextSTEP-2 awards made in 2016 to study development and make ground prototypes of habitat modules that could be used on the Gateway as well as other commercial applications, so the Gateway is likely to incorporate components developed under NextSTEP as well. The PPE will use four 6 kW BHT-6000 Busek Hall-effect thrusters and three 12 kW NASA/Aerojet Rocketdyne Advanced Electric Propulsion System Hall-effect thrusters for a total engine output fractionally under 50 kW. In 2019, the contract to manufacture the PPE was awarded to Maxar Technologies. After a one-year demonstration period, NASA intended to "exercise a contract option to take over control of the spacecraft". Its expected service time is about 15 years. In late 2023, it was reported that flight qualification testing was occurring on the thrusters for the Power and Propulsion Element.Orbit and operations
The Gateway will be deployed in a near-rectilinear halo orbit around the Moon. The eccentricity of the chosen NRHO takes the station within of the lunar north pole surface at closest approach, and as far away as over the lunar south pole, with a period of about 7 days. One of the advantages of an NRHO is the minimal amount of communications blackout with the Earth.Traveling to and from cislunar space is intended to develop the knowledge and experience necessary to venture beyond the Moon and into deep space. The proposed NRHO would allow lunar expeditions from the Gateway to reach a low polar orbit with a Δv of 730 m/s and a half a day of transit time. Orbital station-keeping would require less than 10 m/s of Δv per year, and the orbital inclination could be shifted with a relatively small Δv expenditure, allowing access to most of the lunar surface. Spacecraft launched from Earth would perform a powered flyby of the Moon followed by a NRHO insertion burn to dock with the Gateway as it approaches the apoapsis point of its orbit. The total travel time would be 5 days; the return to Earth would be similar in terms of trip duration and Δv requirement if the spacecraft spends 11 days at the Gateway. The crewed mission duration of 21 days and is limited by the capabilities of the Orion life support and propulsion systems.
Gateway will be the first modular space station to be both human-rated, and autonomously operating most of the time in its early years, as well as being the first deep-space station, far from low Earth orbit. This will be enabled by more sophisticated executive control software than on any prior space station, which will monitor and control all systems. The high-level architecture is provided by the Robotics and Intelligence for Human Spaceflight lab at NASA and implemented at NASA facilities. The Gateway could conceivably also support in-situ resource utilization development and testing from lunar and asteroid sources, and would offer the opportunity for a gradual buildup of capabilities for more complex missions over time.
Structure
For supporting the first crewed mission to the station planned for 2028, the Gateway will begin as a minimal space station composed of only two modules: the Power and Propulsion Element and the Habitation and Logistics Outpost. Both PPE and HALO will be assembled on Earth and launched together on a Falcon Heavy rocket in 2027. They are expected to reach lunar orbit after nine to ten months. The I-Hab module, a contribution from ESA and JAXA, is to be launched on the SLS Block 1B as a co-manifested payload on the Artemis IV crewed Orion mission. All modules will be connected using the International Docking System Standard.Planned modules
- The Power and Propulsion Element started development at the Jet Propulsion Laboratory during the now canceled Asteroid Redirect Mission. The original concept was a robotic, high-performance solar electric spacecraft that would retrieve a multi-ton boulder from an asteroid and bring it to lunar orbit for study. When ARM was canceled, the solar electric propulsion was repurposed for the Gateway. The PPE will allow access to the entire lunar surface and act as a space tug for visiting craft. It will also serve as the command and communications center of the Gateway. The PPE is intended to have a launch mass of with propellant accounting for half that mass and the capability to generate 50 kW of solar electric power for its ion thrusters, which can be supplemented by chemical propulsion. In May 2019, Maxar Technologies was contracted by NASA to manufacture this module, which will also supply the station with electrical power and is based on Maxar's 1300 series satellite bus. The PPE will use Busek 6 kW Hall-effect thrusters and NASA Advanced Electric Propulsion System Hall-effect thrusters. Maxar was awarded a firm-fixed-price contract of US$375 million to build the PPE. NASA is supplying the PPE with an S-band communications system to provide a radio link with nearby vehicles and a passive docking adapter to receive the Gateway's future utilization module. NASA awarded a contract of US$331.8 million to launch PPE on a SpaceX Falcon Heavy in 2027 with the HALO module.
- The Habitation and Logistics Outpost, also called the Minimal Habitation Module and formerly known as the Utilization Module, will be built by Northrop Grumman Innovation Systems. A single Falcon Heavy will launch HALO in 2027 along with the PPE module. The HALO is based directly on a Cygnus Cargo resupply module to the outside of which radial docking ports, body mounted radiators, batteries and communications antennae will be added. The HALO will be a scaled-down habitation module, yet it will feature a functional pressurized volume providing sufficient command, control and data handling capabilities, energy storage and power distribution, thermal control, communications and tracking capabilities, two axial and up to two radial docking ports, stowage volume, environmental control and life support systems to augment the Orion spacecraft and support a crew of four for at least 30 days. The overall HALO mass is expected to be 8–9 tons depending on the final internal layout configuration and launch vehicle lift capability. On 5 June 2020, Northrop Grumman Innovation Systems was awarded a contract, by NASA, of US$187 million to complete the preliminary design of HALO. On 9 July 2021, NASA signed a separate contract with Northrop for the fabrication of HALO, and for integration with the PPE being built by Maxar, for US$935 million. In July 2022, Northrop Grumman awarded Solstar a contract to supply Wi-Fi access for personnel and equipment in the HALO module. On 2 April 2024, it was announced that welding was complete on the module and that the next step was for the module to undergo a series of stress tests upon successful completion of which it would be transported to Northrop Grumman's facility in Arizona for final outfitting. In April 2025 HALO arrived in the US.
- The European System Providing Refueling, Infrastructure and Telecommunications service module will provide additional xenon and hydrazine capacity, additional communications equipment, and an airlock for science packages. It will have a mass of approximately, and a length of. ESA has awarded two parallel design studies, one mostly led by Airbus in partnership with Comex and OHB and one led by Thales Alenia Space. The construction of the module was approved in November 2019. On 14 October 2020, Thales Alenia Space announced that they had been selected by the European Space Agency to build the ESPRIT module. In early 2021, Thales Alenia Space announced effective contract signature. The ESPRIT module will consist of two parts. The first part, called Lunar Link, will provide the communications for the Gateway. It will launch in 2027 pre-attached to the HALO module, for which Thales has separately been awarded a contract by NASA to construct its hull and micrometeoroid protection. The second part, called Lunar View, will contain the pressurized fuel tanks, docking ports and small-windowed habitation corridor and launch in 2029.
- The Lunar I-HAB will be an additional habitation module built by ESA in collaboration with Japan. On 14 October 2020, Thales Alenia Space announced that they had been selected by ESA to build the I-HAB module. The module will include contributions from the other station partners, including a life support system from JAXA, avionics and software from NASA and robotics from the Canadian Space Agency. The module is slated to launch in 2028 on the Artemis IV mission as a co-manifested payload on the SLS Block 1B along with a crewed Orion spacecraft. The I-HAB would have a maximum launch mass of and provide a habitable volume of in order to increase the station's combined habitable volume to.
- The Canadarm3, a pair of robotic remote manipulator arms, one large and one small, broadly similar to the Space Shuttle Canadarm and International Space Station Canadarm2, and associated dextrous manipulator. The arm is to operate autonomously; however, it is also capable of accepting control from ground stations or from astronauts aboard Gateway. The Canadarm3 is to be the contribution of the Canadian Space Agency to this international endeavor. CSA contracted MDA Space to build the arm. MDA previously built Canadarm2, while its former subsidiary, Spar Aerospace, built Canadarm.
- The Crew and Science Airlock Module will be used for performing extravehicular activities outside the space station and would have the docking port for the proposed Deep Space Transport. It will be built by the UAE's Mohammed bin Rashid Space Centre, and is slated for launch around 2030.
Proposed modules
The concept for the Gateway is still evolving, and is intended to include the following modules:- The Gateway Logistics Modules will be used to refuel, resupply and provide logistics on board the space station. The first logistics module sent to the Gateway will also arrive with a robotic arm, which will be built by the Canadian Space Agency.
Assembly in lunar orbit
Crewed flights to the Gateway are expected to use Orion and SLS, while cargo missions are expected to be done by commercial launch providers. In March 2020, NASA announced SpaceX with its future spacecraft Dragon XL as the first commercial partner to deliver supplies to the Gateway.Phase 1
The first two modules will be launched together on a Falcon Heavy rocket no earlier than 2027.| Year | Mission objective | Mission name | Launch vehicle | Human/robotic elements | Status |
| 2027 | Launch of Power and Propulsion Element and Habitation and Logistics Outpost | Falcon Heavy | Robotic | Under development | |
| September 2028 | Delivery of Orion MPCV and I-HAB module | Artemis IV | SLS Block 1B | Crewed | Under development |
| March 2030 | Delivery of Orion MPCV and ESPRIT Refueling Module | Artemis V | SLS Block 1B | Crewed | Under development |
| March 2031 | Delivery of Orion MPCV and Crew and Science Airlock Module | Artemis VI | SLS Block 1B | Crewed | Under development |
| March 2032 | Delivery of Orion MPCV and logistics module | Artemis VII | SLS Block 1B | Crewed | Design phase |
Criticism
NASA officials promote the Gateway as a "reusable command module" that could direct activities on the lunar surface. However, Gateway has received some negative reactions.Michael D. Griffin, a former NASA administrator, said that the Gateway could be useful only after there are facilities on the Moon producing propellant that could be transported to the Gateway. Griffin thinks that after that is achieved, the Gateway would then serve as a fuel depot. In a written testimony to Congress, Griffin stated that the current architecture requiring staging operations at a Gateway based in a lunar polar near-rectilinear halo orbit (NRHO) with a 6.5-day period was disadvantageous in that immediate return to the Gateway from the lunar surface is possible only on 6.5-day centers and that no early human lunar mission should knowingly accept the risk of stranding a crew, whether on the surface or in lunar orbit, for days at a time.
Clive Neal, a University of Notre Dame geologist and advocate for the lunar exploration program, called the Gateway "a waste of money" and stated that NASA is "not fulfilling space policy by building an orbital space station around the Moon".
Former NASA Associate Administrator Doug Cooke wrote in an article on The Hill stating, "NASA can significantly increase speed, simplicity, cost and probability of mission success by deferring Gateway, leveraging SLS, and reducing critical mission operations". He also wrote, "NASA should launch the lander elements on an SLS Block 1B. If an independent transfer element is required, it can be launched on a commercial launcher".
George Abbey, a former director of NASA's Johnson Space Center, said, "The Gateway is, in essence, building a space station to orbit a natural space station, namely the Moon. If we are going to return to the Moon, we should go directly there, not build a space station to orbit it".
Former NASA astronaut Terry W. Virts, who was a pilot of STS-130 aboard and commander of the ISS on Expedition 43, wrote in an op-ed on Ars Technica that the Gateway would "shackle human exploration, not enable it". He also said, "If we don't have the goal, we are putting the proverbial chicken before the egg by developing 'Gemini' before we know what 'Apollo' will look like. Regardless of a future destination, as someone who lived on the ISS for 200 days, I cannot envision a new technology that would be developed or validated by building another modular space station. Without a specific goal, we're unlikely to ever identify one". Virts further criticized NASA for abandoning its planned goal of separating crew from cargo, which was put in place following the Space Shuttle Columbia disaster in 2003.
Apollo 11 astronaut Buzz Aldrin stated that he is "quite opposed to the Gateway" and that "using the Gateway as a staging area for robotic or human missions to the lunar surface is absurd". Aldrin also questioned the benefit of the idea of sending "a crew to an intermediate point in space, pick up a lander there and go down". Conversely, Aldrin expressed support for Robert Zubrin's Moon Direct concept which involves lunar landers traveling from Earth orbit to the lunar surface and back.
Tom Young, a former director of NASA's Goddard Space Flight Center, stated at a hearing at the House Science committee that NASA's portfolio of human spaceflight programs may now be overloaded. "The plate is really full today ... I personally think that the leadership is going to have to, number one, prioritize, but number two is probably to eliminate some of the things that are currently being done that will interrupt having any opportunity of 2024, or I would say even 2028". He said Artemis could be useful in preparations for later missions to Mars but he did not really see a required role for the Gateway in the lunar program.
Mars Society founder Robert Zubrin called the Gateway "NASA's worst plan yet" in an article in the National Review. He said, "We do not need a lunar-orbiting station to go to the Moon. We do not need such a station to go to Mars. We do not need it to go to near-Earth asteroids. We do not need it to go anywhere. Nor can we accomplish anything in such a station that we cannot do in the Earth-orbiting International Space Station, except to expose human subjects to irradiation – a form of medical research for which a number of Nazi doctors were hanged". Zubrin also stated, "If the goal is to build a Moon base, it should be built on the surface of the Moon. That is where the science is, that is where the shielding material is, and that is where the resources to make propellant and other useful things are to be found".
Eric Berger, senior space editor at Ars Technica, stated in an article that the "Gateway introduces costs and complexity into the Artemis Program at a time when NASA is already contending with a superfluity of both" and that "NASA would gain several benefits from canceling Gateway" including a reduction in energy, or delta-v, needed to carry out lunar missions and a simplified lunar landing. Berger also stated that requiring both Orion and Starship to dock with and undock from the Gateway is needlessly complex. In addition, Berger also called for cancelling the Exploration Upper Stage and replacing it with United Launch Alliance's Centaur V upper stage to further simplify the Artemis Program.
Retired aerospace engineer Gerald Black wrote in an article on The Space Review stating that the Gateway is "useless for supporting human return to the lunar surface and a lunar base". He added that it was not planned to be used as a rocket fuel depot and that stopping at the Gateway on the way to or from the Moon would serve no useful purpose and cost propellant.
Mark Whittington, a contributor to The Hill newspaper and an author of several space exploration studies, stated in an article that the "lunar orbit project doesn't help us get back to the Moon". Whittington also pointed out that a lunar orbiting space station was not used during the Apollo program and that a "reusable lunar lander could be refueled from a depot on the lunar surface and left in a parking orbit between missions without the need for a big, complex space station".
Astrophysicist Ethan Siegel wrote an article in Forbes titled "NASA's Idea For A Space Station In Lunar Orbit Takes Humanity Nowhere". Siegel stated that "Orbiting the Moon represents barely incremental progress; the only scientific 'advantages' to being in lunar orbit as opposed to low Earth orbit are twofold: 1. You're outside of the Van Allen belts. 2. You're closer to the lunar surface", reducing the time delay. His final opinion was that the Gateway is "a great way to spend a great deal of money, advancing science and humanity in no appreciable way".
Response from NASA
On 10 December 2018, NASA Administrator Jim Bridenstine said at a presentation "There are people who say we need to get there, and we need to get there tomorrow", speaking of a crewed mission to the Moon, countering with "What we're doing here at NASA is following Space Policy Directive 1", speaking of the Gateway and following up with "I would argue that we got there in 1969. That race is over, and we won. The time now is to build a sustainable, reusable architecture. The next time we go to the Moon, we're going to have American boots on the Moon with the American flag on their shoulders, and they're going to be standing side-by-side with our international partners who have never been to the Moon before".Dan Hartman, the program manager for Gateway, on 30 March 2020, told Ars Technica that the benefits of using Gateway are extending the mission duration, buying down risk, providing research capability and the capability to re-use ascent modules.
GAO 2024 Report
On 31 July 2024, the United States Government Accountability Office found that the Gateway has run into numerous technical problems which have yet to be addressed by NASA. One problem was related to the PPE's ability to keep the Gateway integrated stack in the right orbit and pointing in the right direction when large, heavier vehicles are docked with the Gateway. The report found that although the Gateway is meeting the performance requirements for stack controllability that NASA set for it, those requirements do not account for the mass of some visiting vehicles that plan to dock with the Gateway. The mass of the lunar lander Starship is approximately 18 times greater than the value NASA used to develop the PPE's controllability parameters. Another major problem was that the co-manifested vehicle mass or CMV of the PPE and HALO are both exceeding their mass allocations. The report stated that if NASA cannot reduce the mass, it could affect the Gateway's ability to reach the correct lunar orbit. The report also stated that late design changes to reduce their mass could result in cost growth or schedule delay. Another risk was found related to several defects on a network chip—which affects multiple Gateway components, including the HALO's flight computer and power distribution system which could lead to the Gateway's flight computers to unexpectedly restart and result in loss of control of the Gateway. The proposed 15-year lifespan is also considered to be too short to properly support a crewed mission to Mars.Potential cancellation
On May 2, 2025, the second Trump administration released its fiscal year 2026 budget proposal, which proposed canceling the Lunar Gateway program, citing escalating costs, more cost-effective commercial alternatives and shifting priorities. The proposal included language about the opportunity to repurpose already produced components for use in other missions.On July 4, 2025, President Donald Trump signed the One Big Beautiful Bill Act into law, which included a provision that allocated $2.6 billion to fund the program, and requiring at least $750 million of the total be spent annually from FY 2026 through FY 2028.