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Gateway: First human outpost near the Moon

Special report by Anatoly Zak; Editor: Alain Chabot

After several years of behind-the-scene negotiations, the partners in the International Space Station, ISS, project are quietly putting the finishing touches on a grand plan to extend human presence beyond the Earth's orbit for the first time since 1972 and to establish a pioneering long-term outpost in the vicinity of the Moon, known as Deep Space Gateway, DSG. If this effort manages to overcome all the financial, political and technical hurdles, it might lead to even more ambitious human undertakings in deep space, including a return to the Moon, visits to asteroids and, ultimately, an expedition to Mars! This page is designed to serve as a starting point for our exclusive unofficial coverage and visualization of the project in the coming years.

The architecture of the cis-lunar Gateway in its maximum expansion envisioned by ISS partners in 2019, including the outpost's key components and their sponsoring agencies. Subscribers: click names for access to detailed info on the contemporary status of each element. New readers: click "INSIDER CONTENT" to subscribe.

Origin of the lunar orbital station concept

The concept of an orbital station around the Moon appeared in early American and Soviet studies of lunar exploration. Around 1959, Wernher von Braun envisioned the refueling of transport ships in the lunar orbit. In 1962, Sergei Korolev, the founder of the Soviet space program, considered long-duration "satellite-stations" in lunar orbit to support deep-space expeditions.

Cis-lunar stations near Lagrangian points

At the beginning of the 21st century, or some 240 years after their discovery, Lagrangian points in the Earth-Moon system appeared for the first time on the short list of destinations for manned spacecraft. In its official strategy made public in 2011, NASA said that "initially, exploring the vast expanse of space surrounding the Earth and Moon, including the Lagrange points, will establish a human presence outside of the low Earth orbit...

How it all started

Although at the beginning of the 2010s, NASA proclaimed an expedition to Mars as the ultimate goal of its human space flight program, the US agency agreed with its ISS partners that the road to the Red Planet would go through an outpost in the cis-lunar space.

2017: Deep Space Gateway, DSG

During 2017, the concept of the cis-lunar station made major strides toward leaving a drawing board. In October, US Vice President Mike Pence seemingly came very close to endorsing the project in a major space policy announcement.

2018: Lunar Orbital Platform - Gateway, LOP-G (INSIDER CONTENT)

In 2018, five space agencies continued active negotiations on the design of the near-lunar outpost. At the beginning of the year, the launch of the first piece of the station, the Power and Propulsion Element, PPE, was shifted from NASA's giant SLS rocket to a smaller commercial vehicle and, by April, the second habitation module was reinstated in the outpost's architecture.

2019: LOP-G reaches first development milestone (INSIDER CONTENT)

In February 2019, the international effort to develop a habitable outpost in orbit around the Moon passed a significant engineering review, but Roskosmos was the only member of the development team not to sign off on the completed work.

Focusing on the lunar-surface landing in 2024, NASA pushed the task of completing the cis-lunar station to a period after the return to the Moon, however the multi-national Gateway project apparently managed to adapt to new priorities. Unfortunately, Roskosmos essentially frozen its participation in the ongoing work after 2018.

2021: Specialists detail Gateway's design and operations (INSIDER CONTENT)

By the start of 2021, NASA had all its partners from the International Space Station, ISS, project except for Roskosmos, committed to the development of the Gateway station. With the political support for the project getting stronger at home and abroad, engineers continued working out technical details of the design and operation of the Gateway.

2022: Lunar Gateway faces uncertainty again (INSIDER CONTENT)

Politics, economics and technology are all presenting serious challenges to the Lunar Gateway project, raising questions whether the habitable outpost in orbit around the Moon could be built in time to support lunar expeditions in the 2020s.

NEW, Feb. 8: 2023: Progress and setbacks (INSIDER CONTENT)

In 2023, NASA had to make major revisions in the flight manifest of the Artemis program due to accumulating delays and to make respective adjustments in the Gateway cis-lunar station project, which fully depended on its big sister program.

From the publisher: Pace of our development depends primarily on the level of support from our readers!

How would it work? A multitude of designs and missions

In 2011, the US embarked on the full-scale development of the super heavy booster dubbed the Space Launch System, SLS. The giant rocket would be powerful enough to send around 10 tons of extra cargo along with the Orion crew vehicle beyond the Earth's orbit. As result, each Orion mission could carry a building block of the future outpost to the lunar orbit.

What is it for? To the Moon and beyond

Initially, for NASA, the main goal of the near-lunar station was not the Moon but Mars. For example, the station could perform endurance tests of a closed-loop life-support system needed for missions to the Red Planet and asteroids. New radiation protection and propulsion systems could also be tried. However NASA's partners wanted to use the outpost to explore the Moon itself.

Where would it be? Orbital mechanics

After considering Lagrangian points, engineers chose the Near-Rectilinear Halo Orbit, NRHO, around the Moon for the cis-lunar station. It will keep the outpost always in view of mission control on Earth and beyond the Moon's shadow. During each revolution lasting less than a week, the station will come as close as 1,500 kilometers to the Moon and fly around 70,000 kilometers from the lunar surface at its farthest point.

How much will it cost? (INSIDER CONTENT)

During the Formulation Sync Review, FSR, in September 2018, NASA detailed a possible budget for the cis-lunar station and its major components. According to NASA, the gateway in the lunar orbit would be implementable under the agency's current budget.

Refueling in cis-lunar space (INSIDER CONTENT)

Refueling operations will be critically important for maintaining a human outpost in the lunar orbit. However, in addition to the high cost of delivering propellant to the vicinity of the Moon, refueling will be complicated by the need to develop an entirely new system to transfer and store liquid xenon for the outpost's innovative electric engines, along with the traditional hypergolic propellant.

Scheduling cis-lunar station development (INSIDER CONTENT)

The cis-lunar station program involves an extremely complex network of organizations including space agencies, contractors and scientific teams around the world, which all have to work in sync on multiple aspects and components of the project over many years. To manage their interdependent activities, NASA formed a special Schedule Working Group, SWG, tasked with compiling and updating the project's schedule.

Although in 2017, NASA and its partners agreed that the cis-lunar station would be "parked" in a giant egg-shape orbit known as the Near-Rectilinear Halo Orbit, NRHO, it was always assumed that the outpost could still make occasional sorties to other interesting destinations in the vicinity of the Moon. In 2018, specialists continued defining possible scenarios for possible journeys around the Moon.

Cis-lunar team works on improved rendezvous systems (INSIDER CONTENT)

Specialists working on the project of the cis-lunar station are completing the analysis of potential upgrades aimed to boost the reliability of rendezvous and docking operations between the Orion spacecraft and the components of the future outpost in the lunar orbit.

How risky is the Gateway? (INSIDER CONTENT)

The fact that astronauts and cosmonauts put their lives on the line every time they take seats aboard the spacecraft is well known and obvious, but, mostly beyond the public view, NASA actually puts a real number on the risk for each space mission and establishes requirements for that risk not to exceed a certain threshold. The Gateway project, which takes astronauts beyond Earth's orbit for first time since the Apollo era and therefore, eliminates the possibility for the return home within hours for the first time since the 1970s, has a whole new level of risk to be assessed.

The life-support system for the Gateway-Orion system (INSIDER CONTENT)

In early 2020, NASA established that the Orion crew vehicle would not be able to perform the first American lunar landing since the Apollo program without upgrades to its life-support system. Ironically, the much-vilified Gateway station might prove to be critical in filling the newly found gap in the ship's capabilities to accomplish the Artemis missions.

The Gateway considered for "safe haven" role (INSIDER CONTENT)

In 2019 and early 2020, NASA studied the possibility of the Gateway station serving as a temporary shelter for the crew of a stricken Orion spacecraft in lunar orbit.

The Orion might get late design change (INSIDER CONTENT)

In 2020, NASA planned to introduce a last-minute change in the position of the docking mechanism on its Orion spacecraft, apparently to provide more clearance between the crew vehicle and the near-lunar Gateway, which is expected to be the ship's main destination in the 2020s.

Power and Propulsion Element, PPE

The assembly of the human outpost in lunar orbit was expected to begin with the launch of the Power and Propulsion Element, responsible for the maneuvering, power and communications on the future habitat.

2018: NASA details PPE design (INSIDER CONTENT)

During 2018, a NASA team involved in the project of the space station in the lunar orbit increasingly focused its attention on the development of the Power and Propulsion Element, PPE, which was to become the first piece of the future deep-space outpost.

2019: PPE enters development (INSIDER CONTENT)

On May 23, 2019, NASA announced that Maxar Technologies (formerly MacDonald, Dettwiller and Associates Ltd.) of Westminster, Colo., had been selected to build and launch the PPE module. Maxar also confirmed that it had planned to launch the spacecraft on a commercial rocket at the end of 2022.

2020: PPE continues to evolve (INSIDER CONTENT)

Despite selecting the prime contractor and transitioning to the full-scale development of the first component of the cis-lunar station, the Power and Propulsion Element, PPE, saw a number of design changes in 2020.

NEW, Nov. 1: 2022: First piece of the lunar Gateway takes shape (INSIDER CONTENT)

In 2022, the work on the Power and Propulsion Element, PPE, at the core of the future near-lunar orbital base, transitioned from the drawing board to metal.

•HABITATION AND LOGISTICS OUTPOST, HALO

Habitation module-1 (a.k.a Utilization Element) (INSIDER CONTENT)

During negotiations in Houston in April 2018, NASA proposed the new assembly scenario for the Lunar Orbital Platform - Gateway, LOP-G, program, which brought back the second habitation module into the architecture of the station, almost a year after only a single habitat was left in the design. The "revived" element was now dubbed "Utilization Module" and was provisionally scheduled for launch in 2023.

Habitation and Logistics Outpost, HALO (INSIDER CONTENT)

In the Summer of 2019, NASA re-arranged the architecture of the cis-lunar station to accelerate its ability to support the assembly of the three-component lander which would shuttle the first crew since the Apollo era from the lunar orbit to the surface of the Moon as early as 2024. The new component replaced the ESPRIT refueling module and the Utilization Element in the early configuration of the Gateway.

In the first half of 2020, NASA decided to combine the initial two modules of the future cis-lunar orbital station into a single payload. Joining the Power and Propulsion Element, PPE, with the Habitation and Logistics Outpost, HALO, would allow saving a considerable mass and launch them on one super-heavy rocket, such as Falcon Heavy, which had made two successful flights by that time.

HALO and I-Hab absorb D-Hab systems (INSIDER CONTENT)

In late 2019 and the first half of 2020, international team of engineers worked on re-destributing systems from the cancelled US habitation module among HALO and I-Hab modules. Other modules of the station could also be affected.

2021: HALO leaves the drawing board (INSIDER CONTENT)

Following initial studies of the internal arrangements of the Gateway station in 2020, engineers set about detailing the interior of the HALO. In the meantime, first pieces of the module appeared in metal, as the project reached Preliminary Design Review, PDR.

2022: HALO approaches Critical Design Review (INSIDER CONTENT)

During 2022, Thales Alenia Space was completed welding of the HALO module and prepared it for delivery to Northrop Grumman for outfitting, while the development of the spacecraft reached Critical Design Review, CDR.

Gateway to host lunar sorties (INSIDER CONTENT)

If money allows, the various agencies could cooperate on the development of a manned lander designed for sorties onto the lunar surface. However, the jury is still out on the efficiency of deploying a non-reusable lander at the station, versus flying independent expeditions to the Moon without a way station. Unlike most agencies, NASA is skeptical about the whole idea, because it would take the focus away from Mars. Russian studies of the lunar lander

Ascent Element for the piloted lunar lander (INSIDER CONTENT)

After receiving a political deadline for delivering a crew to the surface of the Moon in 2024, NASA wasted no time formulating the early architecture of a lunar lander. Engineers worked on the technical specifications of the three-element complex which would be based at the cis-lunar outpost. Its top component would be the Ascent Element with the crew cabin and the engines for the takeoff from the Moon.

Descent Element for the piloted lunar lander (INSIDER CONTENT)

The most distinct element that defines the architecture of any lunar-landing vehicle is its descent stage responsible for braking on its way down and equipped with landing gear for a soft touchdown on the Moon. This is no exception for the three-element lunar lander which would be a part of the international cis-lunar Gateway.

Transfer Element for the piloted lunar lander (INSIDER CONTENT)

Unlike the "classic" two-stage designs from the Moon Race era, the crew lander based at the cis-lunar Gateway will need a third element. Because the trip from the very high lunar orbit of the proposed station will require a considerable "push" to reach the low orbit around the Moon before the final braking and descent to the surface could begin, it would not be practical to carry all the necessary propellant for the maneuvers aboard a single descent stage. Hence, the addition of a transfer space tug.

ESPRIT module

A major re-write of the assembly schedule for the Gateway early in 2017 put severe mass restrictions on the first component of the outpost. To resolve the problem, European engineers proposed a new robotic vehicle to take over some of the tasks of the original Power and Propulsion Bus.

Europe ponders ESPRIT architecture (INSIDER CONTENT)

During 2018, engineers at the European Space Agency, ESA, and its industrial contractors conducted comparative studies of different architectures for the ESPRIT. At the time, the module was scheduled for launch at the end of 2023 in the cargo section of NASA's super-heavy SLS rocket, along with the US-built Utilization Element and topped with the Orion crew vehicle.

ESPRIT becomes a stand-alone module (INSIDER CONTENT)

In 2019, the European Space Agency, continued work on the ESPRIT module, its first component for the cis-lunar Gateway station. In the course of the year, the European concept experienced drastic changes stemming from the major shift in the American space strategy and its effect on the architecture of the cis-lunar outpost.

Cis-lunar station gets panoramic windows (INSIDER CONTENT)

Continuing design work on the refueling module, ESPRIT, for the Gateway outpost near the Moon in 2020, European engineers expanded its architecture with an observation deck providing a 360-degree view of space.

Gateway's refueling module continued to evolve in 2022 (INSIDER CONTENT)

Before setting in stone the design of the ESPRIT module, European engineers made final tweaks on the drawing board with some dramatic increase in capabilities for the spacecraft intended to operate in a lunar orbit.

•INTERNATIONAL HABITATION MODULE, I-HAB

International habitation module (I-Hab)

From the outset of the project, the partners agreed to build at least two habitation modules for the crew of the cis-lunar outpost. Not surprisingly, the European Space Agency, ESA, took responsibility to provide the modules, based on Europe's experience in the Columbus and Spacelab programs

NASA refines I-Hab design in 2019 (INSIDER CONTENT)

In 2019, engineers working behind the scene on the American habitation module for the cis-lunar Gateway station made several design changes to better adapt the element for the still evolving architecture and goals of the overall project.

I-Hab module prepares to leave the drawing board (INSIDER CONTENT)

In 2021, European and Japanese engineers were putting the finishing touches on the design of a habitation module intended to expand the cis-lunar Gateway station planned for orbit around the Moon.

Metal-cutting begins for the I-Hab module (INSIDER CONTENT)

In 2022, first components of the I-Hab module appeared in metal at the assembly facility of Thales Alenia Space in Italy.

NEW, Feb. 8: I-Hab in 2023 (INSIDER CONTENT)

In 2023, European specialists at Thales Alenia Space initiated active assembly of the I-Hab module for the Gateway, but its launch date kept slipping toward the end of the 2020s.

•US HABITATION MODULE, D-HUB

In May 2018, NASA added another US-built habitation module to the Lunar Orbital Platform, LOP-G. It was identified as the Domestic Habitation Module, or D-Hab, and penciled for launch no earlier than 2025. Not counting logistical components, D-Hab would be the third pressurized piece of the near-lunar outpost.

NASA refines D-Hab design in 2019 (INSIDER CONTENT)

In 2019, engineers working behind the scene on the American habitation module for the cis-lunar Gateway station made several design changes to better adapt the element for the still evolving architecture and goals of the overall project.

•AIRLOCK MODULE, SHM

Russian airlock module

By June 2016, Russia limited its role in the cis-lunar project to an airlock module, whose concept was formulated at the nation's key human space flight contractor, RKK Energia, by October of the same year. During its flight to the lunar vicinity either on NASA's SLS or on Russia's own Angara-5/KVTK rocket, the module would double as a cargo vehicle.

Russia rethinks airlock concept (INSIDER CONTENT)

By April 2018, RKK Energia detailed the configuration of the Airlock Module, conceived as Russia's primary contribution to the future international outpost in lunar orbit.

Airlock postponed to 2028, moved from SLS to Russian rocket (INSIDER CONTENT)

Although the Russian-proposed airlock module finally replaced the US notional designs of this element in the official NASA images of the lunar Gateway by 2019, behind the scene, the work stalled on what was the only contribution to the US-led project which Roskosmos tentatively committed to.

NEW, Feb. 8: Partners consider new functions for airlock (INSIDER CONTENT)

Although around 2019 Roskosmos put a freeze on its contribution to the future US-led Gateway station around the Moon, other international participants considered shifting a scientific airlock to the Russia-assigned module.

NEW, Feb. 8: UAE replaces Russia as supplier of airlock (INSIDER CONTENT)

Marking a major reshuffle in the exclusive space club, the United Arab Emirates took the seat on the Gateway project in 2023 that had been vacated by Roskosmos in the late 2010s.

Deep-Space Transport, DST

In the second phase of the assembly at the end of the 2020s, NASA hopes to equip the cis-lunar platform with a bigger better habitation and propulsion module, which would be capable of deep-space missions, possibly even to the vicinity of Mars. It will generate up to 150 kilowatts of power and feature the latest electric propulsion system.

Robotic lunar lander, HLEPP

The cis-lunar outpost is also expected to serve as a home and, possibly, a mission control center for a robotic lunar lander designed to collect and return soil samples from the surface of the Moon. As of 2016, European, Japanese and Canadian space agencies hoped to pool funding to build the rover-carrying unmanned platform for the project, known as the Human Lunar Exploration Precursor Program, HLEPP.

Robotic arm (INSIDER CONTENT)

Capitalizing on its extensive experience in the Space Shuttle and the ISS programs, the Canadian Space Agency promised to provide a sophisticated robotic arm for the cis-lunar base. The device was expected to ride into space, strapped to the very first piece of the outpost -- the propulsion module.

Near-lunar spacesuit (INSIDER CONTENT)

NASA and Roskosmos have made the first step to integrate a prospective American spacesuit with the Russian module serving as an airlock aboard the Lunar Orbital Platform, LOP-G.

The science airlock will allow the crew to take experiments and other payloads from the short-sleeve environment of the Deep Space Gateway to the vacuum of space in the vicinity of the Moon. It could also serve as an entry point for containers with precious soil samples delivered by robotic vehicles from the surface of the Moon to the lunar orbit. Last but not least, during long expeditions aboard the near-lunar gateway, the crew could use the science airlock to dispose of trash.

Russian Lunar Mission Support Module

The Russian political decision in the summer of 2017 to participate in the development of the DSG project, prompted engineers to consider again possible Russian contributions to the project. One concept prepared for the Checkpoint Review meeting in October 2017 included a Lunar Mission Support Module.

Russia quietly drafts lunar orbital station of its own! (INSIDER CONTENT)

In 2018, facing uncertainty in its cooperation with the West, Roskosmos began formulating a new concept for a national cis-lunar station relying on a pair of modules originally slated for the International Space Station in the Earth's orbit. The proposed plan might be shared with NASA during the first meeting of newly appointed heads of Russian and US space agencies next month.

Russian lunar station still on the agenda in 2019 (INSIDER CONTENT)

Russian engineers continue studying various options for launching a large habitat into the lunar orbit which could join the US-led cis-lunar Gateway or operate as an inpendent space station.

Gateway assembly scenarios as of mid-2018 (INSIDER CONTENT)

The first detailed assembly scenario for the cis-lunar Gateway emerged in 2018, depicting all major configuration of the outpost during its construction in orbit.

Assembly scenarios as of August 2019 (INSIDER CONTENT)

During 2019, engineers drastically redesigned assembly scenario to reflect the latest changes in the project itself and to address the new priorities in NASA's exploration strategy. The latest mission sequence, the new architecture of the outpost and its estimated mass at each stage of assembly became the basis for the the Integrated Analysis Cycle, IAC-4.

Logistics and cargo ships (INSIDER CONTENT)

Various concepts of unmanned vehicles carrying cargo to the cis-lunar outpost have been under consideration in the past couple of years. Cargo flights would be required to extend the presence of the crews on the outpost beyond the few days afforded by the life-support system of the manned spacecraft.

Logistics Augmentation Module, LAM (INSIDER CONTENT)

The Logistics Augmentation Module, LAM, was conceived to be the first cargo supply mission launched toward the near-lunar station on an expendable commercial rocket. Overall, it would be the third flight to assemble and maintain the human outpost in the vicinity of the Moon.

Japan mulls Falcon Heavy-launched cargo ship for cis-lunar station (INSIDER CONTENT)

In 2018, the Japanese space agency, JAXA, formulated an early concept of a robotic vehicle intended for a one-time re-supply of the cis-lunar station. The spacecraft would be propelled to its destination on a SpaceX' Falcon Heavy rocket.

Russian cargo ship (INSIDER CONTENT)

In 2019, in the latest round of assessment of possible contributions to the international lunar gateway, Russian engineers mulled a specialized version of cargo ship which could reach the outpost by way of a domestically built rocket.

Dragon-XL cargo ship (INSIDER CONTENT)

On March 27, 2020, NASA announced that SpaceX company had been selected to be the first provider of pressurized and unpressurized supplies and experiments to the Gateway.

Orion transport spacecraft

The first and only vehicle capable of delivering astronauts to the outpost (at least initially) will be NASA's Orion spacecraft launched on the giant SLS rocket. Most of the station's components will hitchhike to the lunar vicinity along with the Orion. By the time, it carries its first crew, NASA will have spent nearly two decades for the Orion's development.

PTK/Federatsiya spacecraft

As of 2016, Roskosmos promised that its new-generation transport spacecraft, PTK NP/Federatsiya will have a rocket large enough to send it beyond the low Earth orbit around 2027. If ever built, the PTK will provide an alternative to the Orion for astronauts and cosmonauts to reach the cis-lunar base.

Ryvok transport vehicle (INSIDER CONTENT)

At the beginning of 2019, Roskosmos leadership looked at possible engineering ideas which could allow the fast development of a new transport system to the lunar orbit. One concept, which caught attention of Roskosmos head Dmitry Rogozin, relied on an aerodynamic heat-shield to ease the spacecraft into the Earth's orbit without use of propellant in a method known as aerobraking.

NASA's SLS rocket

NASA's super-heavy rocket known as the Space Launch System or SLS was approved for development in 2011 and it is promised to be ready for the first test launch at the end of 2019. SLS derived from the Ares-5 rocket, first envisioned around 2003.

Russian super-heavy rocket

In 2016, the Russian space officials concluded that a super-heavy launcher would be the only efficient way for carrying crews to the Moon. However, with all the economic problems facing the Russian economy, the big rocket is not expected to appear on the scene until the late 2020s.

Russian launchers: Proton and Angara-5/KVTK

Although the key mission for the Angara-5V rocket would be to compete on the commercial market and deliver the heaviest military payloads, the rocket could fins some role in human missions beyond the Earth's orbit. As many as four Angara-5Vs would be required to put a crew on the lunar surface with the use of the 20-ton next-generation PTK NP spacecraft and a separately launched lander.

All articles and illustrations inside this section by Anatoly Zak unless stated otherwise. All rights reserved

Last update: February 8, 2024