The Lunar Gateway was a planned modular space station that would have been assembled in orbit around the Moon as part of the Artemis program. Derived from earlier concepts such as the Exploration Gateway Platform, it was developed from 2017 until 2026, when the leading space agency NASA shifted focus to developing a lunar surface base. The elements of Gateway are expected to be repurposed for other projects.
The project was developed with international partners including the European Space Agency (ESA), the Japan Aerospace Exploration Agency (JAXA), the Canadian Space Agency (CSA), and the Mohammed Bin Rashid Space Centre (MBRSC) of the United Arab Emirates.
One of the technical drivers for Gateway was the limited propulsion capability of Orion's European Service Module used for the Artemis missions, which could not independently depart from low lunar orbit. A near-rectilinear halo orbit was selected, which reduced propulsion requirements. Gateway was intended to serve as a staging point where Orion could rendezvous with Human Landing System lunar landers, transfer crews, and support lunar surface missions. It was also planned to support communications, scientific research, and habitation for both crewed and robotic missions. Before its cancellation, it was expected to be the first space station beyond low Earth orbit and a potential staging point for future human missions to Mars.
Development plans called for two initial modules, the Power and Propulsion Element (PPE) and the Habitation and Logistics Outpost (HALO). Mid-way through the effort a plan emerged to launch them together on a commercial rocket. Subsequent elements were to be launched on Space Launch System (SLS) missions as co-manifested payloads with Orion and transferred to lunar orbit.
Overview The Gateway was 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 would have also been used to evaluate concepts needed for long-duration deep-space missions.
Scientific research which would have been studied on Gateway were 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 (PPE) and the Habitation and Logistics Outpost (HALO), began in the early 2020s. The PPE and HALO were planned to launch together on a Falcon Heavy before Gateway's cancellation, and the first crewed visits were expected to be part of Artemis IV, which was scheduled to launch no earlier than September 2028. However, the NASA Office of Inspector General (OIG) reported that HALO was unlikely to be ready for launch until 2032.
Name The station was initially announced as the Deep Space Gateway (DSG) in 2017. NASA's FY 2019 budget request renamed the station as Lunar Orbital Platform-Gateway (LOP-G).
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 (PPE) 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 (RASC-AL) 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 2 May 2018, NASA stated the International Space Exploration Coordination Group (ISECG), a non-binding coordination forum comprising 14 (at the time) worldwide space agencies, identified the Gateway as a critical component in expanding human presence to the Moon, Mars, and deeper into the Solar System.
In 2019 NASA established a Lunar Gateway Program Office at Johnson Space Center.
International participants
On 27 September 2017, an informal joint statement on cooperation between NASA and Russia's Roscosmos was announced. However, in October 2020, Dmitry Rogozin, director general of Roscosmos, said that the program was too "U.S.-centric" for Roscosmos to participate. In January 2021, Roscosmos announced that it would not participate in the program.
Prior to cancellation, the Canadian Space Agency (CSA), the European Space Agency (ESA), Japan Aerospace Exploration Agency (JAXA) and Mohammed Bin Rashid Space Centre (MBRSC) were planning to participate in the Gateway project, contributing a robotic arm, refueling and communications hardware, habitation and research capacity, and an airlock module. These international elements were planned to launch after the initial NASA PPE and HALO elements were placed in 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 (PPE), 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 Gateway was likely to incorporate components developed under NextSTEP as well. The PPE would have used four 6 kW BHT-6000 Busek Hall-effect thrusters and three 12 kW NASA/Aerojet Rocketdyne Advanced Electric Propulsion System (AEPS) 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 was about 15 years.Jason Crusan. Gateway Update NASA Advisory Council, Human Exploration and Operations Committee, 7 December 2018 In late 2023, it was reported that flight qualification testing was occurring on the thrusters for the Power and Propulsion Element.
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, commercial alternatives, and shifting priorities, while allowing for repurposing of existing components. On July 4, 2025, President Donald Trump signed the One Big Beautiful Bill Act into law, providing $2.6 billion for the program and requiring at least $750 million annually from FY 2026 through FY 2028.
In early 2026, references to the station were reportedly removed from congressional funding legislation, and NASA administrator Jared Isaacman was reported to be considering restructuring the program toward a lunar surface base. In March 2026, NASA confirmed it would pause Gateway as designed and instead focus on a lunar surface base for 2029–2036, repurposing hardware where possible.
NASA also announced that the Power and Propulsion Element would be repurposed for Space Reactor-1 Freedom, a proposed nuclear electric propulsion spacecraft.
The NASA OIG reported that, at cancellation, NASA had spent nearly $1.9 billion on HALO (up from the $1.3 billion contract value), with delivery projected for October 2026, beyond the original May 2025 commitment, and that corrosion in its primary structure could have delayed delivery to July 2031.
The ESA stated that, despite cancellation, it expected to continue development of most planned hardware for Gateway. The Lunar I-Hab would proceed through critical design review before a repurposing decision would be made. Lunar Link was being assessed for reuse as a dedicated Lunar communications satellite. Development of Lunar View would slow with the agency saying it would keep the technology for future deep space exploration.
Orbit and operations The Gateway was to be deployed in a near-rectilinear halo orbit (NRHO) 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.Angelic halo orbit chosen for humankind's first lunar outpost. European Space Agency, Published by PhysOrg, 19 July 2019<ref name="SN-20190916}} One of the advantages of an NRHO is the minimal amount of communications blackout with the Earth.
Traveling to and from cislunar space (lunar orbit) is intended to develop the knowledge and experience necessary to venture beyond the Moon and into deep space. The proposed NRHO would have allowed 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 have required less than 10 m/s of Δv per year, and the orbital inclination could have been shifted with a relatively small Δv expenditure, allowing access to most of the lunar surface. Spacecraft launched from Earth would have performed a powered flyby of the Moon followed by a NRHO insertion burn to dock with the Gateway as it approached the apoapsis point of its orbit. The total travel time would be 5 days; the return to Earth would have been similar in terms of trip duration and Δv requirement if the spacecraft had spent 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.