Lunar Gateway

• 1. Introduction

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  The Lunar Gateway was never going to orbit Earth. It was designed to circle the Moon instead, and Apollo 11 astronaut Buzz Aldrin wanted no part of it. Aldrin said he was "quite opposed to the Gateway" and called the idea of using it as a staging area for lunar missions "absurd." NASA spent years developing the project anyway. What problem was this station supposed to solve? Why did so many veterans of the space agency line up against it? And what finally became of a project once billed as humanity's first space station beyond low Earth orbit?

• 2. A Problem With Orion

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  Orion's European Service Module could not, on its own, leave low lunar orbit, and that single limitation shaped the entire Gateway concept. NASA needed a place where its Orion crew capsule could meet up with a lander without requiring more propulsion than the service module could provide. Engineers picked a near-rectilinear halo orbit around the Moon, a path that cut the fuel needed for Orion to reach and leave it. Decades earlier, the Apollo Command and Service Module had already proven the basic idea. It became the first crewed lunar orbiting spacecraft to dock and transfer crew with another vehicle, the Apollo Lunar Module.

  From the latter half of the 2020s onward, Gateway was meant to provide docking ports and communications relays for Orion and landers such as Starship HLS. It was designed as a staging point for missions to the lunar south polar region and as a platform for crewed transfers. It would also have let engineers test ideas for long-duration deep-space travel. Researchers planned to use it for planetary science, astrophysics, Earth observation, space biology, heliophysics, and studies of human health and performance far from Earth.

  Construction of the station's first elements, the Power and Propulsion Element and the Habitation and Logistics Outpost, began in the early 2020s. Before cancellation, both were slated to launch together on a Falcon Heavy rocket. The first crewed visit was expected as part of Artemis IV, scheduled no earlier than September 2028.

• 3. How Gateway Got Its Name

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  NASA first announced the station in 2017 under the name Deep Space Gateway. Its FY 2019 budget request renamed it the Lunar Orbital Platform-Gateway, before NASA officially settled on simply Gateway in November 2019. The station's logo drew its design from the Gateway Arch, the landmark in St. Louis.

  An earlier NASA proposal for a station in cislunar space, called the Deep Space Habitat, had already surfaced publicly in 2012. That proposal led to funding in 2015 under the NextSTEP program to study what a deep space habitat would require. By February 2018, NASA said those NextSTEP studies, together with other International Space Station partner studies, would guide the required capabilities for Gateway's habitation modules. The Power and Propulsion Element itself traced back to the canceled Asteroid Redirect Mission, which had originally developed the solar electric propulsion concept.

  On the 7th of November 2017, NASA invited the global science community to propose studies that could take advantage of Gateway's location in cislunar space. Denver, Colorado hosted the resulting Deep Space Gateway Concept Science Workshop, running from the 27th of February to the 1st of March 2018. Over three days, 196 presentations were given. That same year, NASA launched the RASC-AL competition, asking university teams to design Gateway concepts across four themes, from uncrewed operations to a cislunar tug. Twenty teams were selected to develop their ideas. Fourteen presented in person in June 2019 at a forum in Cocoa Beach, Florida, each receiving a US$6,000 stipend. A team from the University of Puerto Rico at Mayagüez won with a concept for lunar exploration and access to the polar regions.

  On the 2nd of May 2018, NASA cited a forum of 14 space agencies, the International Space Exploration Coordination Group. The group had named Gateway a critical piece of expanding human presence toward the Moon, Mars, and deeper into the Solar System. NASA formalized its commitment in 2019 by establishing a Lunar Gateway Program Office at Johnson Space Center.

• 4. Partners Across The World

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  On the 27th of September 2017, NASA and Russia's Roscosmos announced an informal joint statement on cooperation for the station. That partnership collapsed by October 2020, when Roscosmos director general Dmitry Rogozin called the program too "U.S.-centric" for his agency to join. Russia formally declined to participate in January 2021.

  Four other partners stayed in. They were the Canadian Space Agency, the European Space Agency, and the Japan Aerospace Exploration Agency. A fourth partner, the Mohammed Bin Rashid Space Centre of the United Arab Emirates, also joined. Between them they were contributing a robotic arm, refueling and communications hardware, habitation and research capacity, and an airlock module. All of it was planned to launch after NASA's own elements reached lunar orbit.

  On the 1st of November 2017, NASA commissioned five companies to study ways of building the Power and Propulsion Element. Those companies were Boeing, Lockheed Martin, Orbital ATK, Sierra Nevada, and Space Systems/Loral, and their combined studies carried a budget of US$2.4 million. Maxar Technologies won the actual contract in 2019 and built the module on its 1300-series satellite bus. It carried four 6 kW Busek Hall-effect thrusters and three 12 kW NASA/Aerojet Rocketdyne thrusters, for a combined output just under 50 kW. NASA planned to run the module for a year before exercising a contract option to take control of it.

  Northrop Grumman won the contract in 2020 to build the Habitation and Logistics Outpost, basing it on its Cygnus cargo spacecraft design. HALO was meant to hold a crew of four for at least 30 days and to launch together with the Power and Propulsion Element.

  Thales Alenia Space was building the European ESPRIT module, split into a communications package called Lunar Link and a refueling element called Lunar View. ESA and JAXA together developed I-HAB, an additional pressurized habitation module planned to launch as a co-manifested payload with the crewed Artemis IV mission. The Canadian Space Agency's Canadarm3 paired a large robotic arm with a smaller, dexterous one for autonomous and remote maintenance work. The Mohammed Bin Rashid Space Centre was developing the Crew and Science Airlock Module, planned to launch with the crewed Artemis VI mission. It was meant to support spacewalks and the deployment of external payloads. Every one of these later modules was designed to join the station using the International Docking System Standard.

• 5. In Orbit

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  The chosen near-rectilinear halo orbit brought Gateway within 1500 km of the lunar north pole at closest approach. At its farthest, the station reached 70000 km over the south pole, completing a lap roughly every 7 days. That eccentric path minimized the blackout periods when the station would lose communication with Earth.

  A spacecraft launching from Earth would first perform a powered flyby of the Moon, using a Δv of about 180 m/s. It would then fire an insertion burn of about 240 m/s to reach the station near the high point of its orbit. The whole trip from Earth to dock with Gateway was expected to take 5 days. A crew staying 11 days at the station would face a similar return trip. A full crewed mission of 21 days would need a Δv of about 840 m/s, a limit set by Orion's life support and propulsion systems.

  Once docked at Gateway, a mission could reach a low lunar polar orbit using a Δv of 730 m/s and half a day of transit time. Keeping the station in its orbit required less than 10 m/s of Δv per year. NASA could also shift the orbit's inclination with relatively little additional propellant, opening access to most of the lunar surface.

  Gateway was designed as the first modular space station to be both human-rated and mostly autonomous in its early years. It would have run on more sophisticated control software than any station before it. NASA's Robotics and Intelligence for Human Spaceflight lab was responsible for the high-level architecture behind that software. The station could also have supported in-situ resource utilization testing using lunar and asteroid material, gradually building toward more complex future missions.

• 6. Voices Against Gateway

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  Michael D. Griffin, a former NASA administrator, told Congress in written testimony that Gateway's near-rectilinear halo orbit had a 6.5-day period. That period limited any return from the lunar surface to the same 6.5-day cycle. Griffin argued that no early human lunar mission should knowingly risk stranding a crew for days at a time. He said Gateway could only become useful once facilities on the Moon were producing propellant to ship there. At that point, he said, it might work as a fuel depot.

  Former NASA Associate Administrator Doug Cooke wrote in The Hill that delaying Gateway and relying more on the SLS rocket could speed up the program. He said the change would also cut costs and simplify operations. Cooke proposed launching lander elements directly on an SLS Block 1B rocket, with a commercial launcher handling any separate transfer element if one were needed.

  George Abbey, a former director of NASA's Johnson Space Center, offered a blunt description of Gateway. He called it "building a space station to orbit a natural space station, namely the Moon." He argued that a return to the Moon should go there directly instead.

  Tom Young, a former director of NASA's Goddard Space Flight Center, told the House Science committee that the agency's human spaceflight portfolio was overloaded. Young said NASA's leadership needed to prioritize and eliminate programs that could delay missions planned for 2024 or 2028. He still saw a role for Artemis in preparing for future Mars missions.

  University of Notre Dame geologist Clive Neal called Gateway "a waste of money." He said NASA was failing to fulfill space policy by building an orbital station around the Moon. Mars Society founder Robert Zubrin, writing in the National Review, called Gateway "NASA's worst plan yet." He argued that nothing achievable at Gateway could not already be done aboard the International Space Station. Zubrin said any Moon base should be built on the lunar surface, where the science, shielding, and resources actually are. Aldrin, despite opposing Gateway, voiced support for Zubrin's competing Moon Direct concept of landers flying straight from Earth orbit to the lunar surface and back.

  Retired aerospace engineer Gerald Black, writing in The Space Review, called Gateway "useless for supporting human return to the lunar surface and a lunar base." Stopping there, he added, would cost propellant for no real benefit. Astrophysicist Ethan Siegel titled a Forbes article "NASA's Idea For A Space Station In Lunar Orbit Takes Humanity Nowhere." He argued lunar orbit offered only two real advantages over low Earth orbit. Those were escaping the Van Allen belts and cutting the time delay to the lunar surface.

  Eric Berger, senior space editor at Ars Technica, wrote that Gateway added cost and complexity to Artemis when NASA already had plenty of both. Berger said cancelling Gateway would cut the delta-v needed for lunar missions and simplify landings. He also called for replacing the Exploration Upper Stage with United Launch Alliance's Centaur V. Mark Whittington, a contributor to The Hill, wrote that the project "doesn't help us get back to the Moon." He noted that the Apollo program had never used a lunar orbiting station at all.

• 7. NASA Answers Back

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  On the 10th of December 2018, NASA Administrator Jim Bridenstine told an audience that some people wanted an immediate return to the Moon. He countered that NASA was following Space Policy Directive 1, arguing "we got there in 1969" and that race was over. Bridenstine said the goal now was a sustainable, reusable architecture, with American astronauts standing beside international partners who had never been to the Moon.

  Dan Hartman, Gateway's program manager, told Ars Technica on the 30th of March 2020 that the station extended mission duration and reduced risk. He also said it offered fresh research capability. Flying to the Moon without Gateway limited crews to whatever supplies a lander or Orion alone could carry, Hartman said. A single logistics module at Gateway, he added, could stretch a mission from 30 to 60 days. He said more time in lunar orbit meant more crew research into human health in deep space. It also meant a better chance to reuse ascent modules across missions. Hartman called Gateway a resource for buying down risk on the way to both the Moon and eventual missions to Mars.

• 8. The End Of Gateway

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  On the 31st of July 2024, the United States Government Accountability Office reported that Gateway had run into technical problems NASA had yet to resolve. One issue involved the Power and Propulsion Element's ability to keep the station's stack pointed correctly once large, heavy vehicles docked with it. The mass of the lunar lander Starship was about 18 times greater than the value NASA had used to set those controllability requirements. The report also found that the combined mass of the Power and Propulsion Element and HALO exceeded their co-manifested vehicle mass allocations. That problem could force late design changes, drive up cost, or delay the schedule. Investigators flagged a defect in a network chip used across multiple Gateway components, including HALO's flight computer and power distribution system. That defect could cause the flight computers to unexpectedly restart, and the station to lose control. The report also judged the station's proposed 15-year lifespan too short to properly support a crewed mission to Mars.

  Less than a year later, on the 2nd of May 2025, the second Trump administration released its fiscal year 2026 budget proposal. It called for cancelling the Lunar Gateway program entirely, citing rising costs, commercial alternatives, and shifting priorities. The proposal did leave room to repurpose existing hardware. On the 4th of July 2025, President Donald Trump signed the One Big Beautiful Bill Act. The law allocated $2.6 billion to the program and required at least $750 million a year from fiscal year 2026 through fiscal year 2028.

  Early in 2026, reports found that references to the station had disappeared from congressional funding legislation. By the 26th of February 2026, NASA Administrator Jared Isaacman was said to be weighing a restructure toward a lunar surface base centered in Houston. NASA made it official in March 2026, announcing it would pause the station as designed. It would instead pursue a lunar surface base planned for between 2029 and 2036, reusing Gateway hardware and partner contributions where it could.

  Carlos Garcia-Galan, NASA's deputy program manager for Gateway, was reassigned to lead that surface base effort. He said a lunar orbiting outpost "has value in our overall exploration goals." NASA might revisit the idea later, he added, even as the agency focused on the surface for now. At the same news conference, NASA said the Power and Propulsion Element would be repurposed into Space Reactor-1 Freedom. That proposed spacecraft is meant to be the first nuclear fission-powered interplanetary mission and to demonstrate nuclear electric propulsion in deep space. The European Space Agency is expected to announce its decision in June 2026 on the fate of its Gateway components.