After a 50-year hiatus, a U.S.-led initiative to resume deep-space human exploration faced a critical flight test of NASA’s new Saturn V-class rocket and its Orion capsule, which is designed to support four astronauts for 21 days beyond the protective shield of Earth’s magnetosphere.

• Satellites feature novel sensors, propulsion and software
• Small spacecraft planned to venture beyond Earth orbit

Only mannequins and science experiments, many of which monitor radiation levels, are aboard for the Artemis I flight test, which was scheduled to launch on Aug. 29 from the Kennedy Space Center. If the superheavy-lift Space Launch System (SLS) rocket and Orion deep-space capsule perform as expected, Artemis II will follow in about two years with astronauts aboard for a second shakedown cruise in lunar orbit.

The pace and complexity of these missions accelerates with Artemis III, which is expected to mark the return of U.S. astronauts to the lunar surface for the first time since the final Apollo Moon mission in December 1972. Unlike Apollo, which stemmed from a technological showdown with the former Soviet Union, Artemis is designed as an open-ended, science-driven program to build the expertise and experience needed to send humans to Mars. Also unlike Apollo, the U.S. is not undertaking the Artemis program alone.

As the supplier of the Orion service module, the European Space Agency (ESA) is an early, critical partner. “Many of us—myself included—have been inspired and drawn to space or other technology domains thanks to the Apollo Moon landings,” ESA Director General Josef Aschbacher says.

The program was “an enormous boost for the U.S.—economically, technologically and to establish the country as a leading nation globally,” Aschbacher adds. “This impact is still felt today, which shows how important space is for the evolution and the positioning of a country.”

ESA’s involvement with Artemis I is just one leg of a multifaceted, long-term strategy to sustain and expand a U.S.-led space exploration strategy—one that builds not only on partnerships with nations but also on financial and technical alliances with private companies. At the top of the list of commercial partners is SpaceX, which is developing a variant of its Starship-Super Heavy transportation system to ferry astronauts from lunar orbit to the surface of the Moon. SpaceX plans an uncrewed demonstration of its Starship Human Landing System (HLS) in 2024. NASA optimistically is targeting the first post-Apollo landing on the Moon in late 2025. The agency’s Office of Inspector General (OIG), in a November 2021 audit, estimated that the Artemis III lunar landing more likely would be 2-3 years beyond that.

It is not just the complicated Starship HLS architecture that gives the OIG pause. The system requires an in-space fuel depot, multiple Starship launches to fill it and the technology to transfer propellants in space. The lander itself is so tall that SpaceX plans to include an elevator to ferry astronauts from the crew cabin to the lunar surface.

The development of new spacesuits for astronauts to wear while walking on the Moon is another concern. Similar to its agreement with SpaceX (and a to-be-determined second provider) for HLS services, NASA is turning to partnership agreements with private companies to supply spacesuits under Exploration Extravehicular Activity Services (xEVAS) contracts.

In June, the space agency selected  Axiom Space and Collins Aerospace as part of a potential $3.5 billion public-private partnership to develop, operate and provide training for extravehicular activity spacesuits for Artemis moonwalkers, as well as for future spacewalks outside the International Space Station (ISS). The suits are intended to accommodate a broader range of individuals to support the assignment of a more diverse group of astronauts to deep-space and low-Earth-orbit missions.

In addition to the HLS and xEVAS efforts, the Artemis program currently includes:

• An upgraded SLS, known as Block 1B, that replaces the single-engine Interim Cryogenic Propulsion Stage upper stage planned for the first three Artemis missions with the Exploration Upper Stage (EUS), powered by four Aerojet Rocketdyne RL10 engines. With the EUS, an SLS could send more than 83,000 lb. toward the Moon, compared with the current lift capacity of 59,000 lb.
• The Mobile Launcher 2 (ML-2), which will be used to assemble, process and launch the SLS Block 1B rocket and Orion spacecraft. NASA awarded Bechtel a $383 million contract in 2019 to design, build, test and commission the ML-2, but the OIG in June 2022 determined that the project will cost 2.5 times more and will not be available until October 2025—2.5 years later than planned.
• The Gateway Power and Propulsion Element (PPE), Gateway Habitation and Logistics Outpost (HALO) and Gateway deep-space logistics—the starting elements for an outpost in lunar orbit that will be used to stage sorties to the surface of the Moon, test technologies needed for human travel to Mars and host science experiments.

The Gateway, which will be about one-sixth the size of the ISS, will be unoccupied and remotely operated during much of its planned 15-year design life but capable of supporting four-member crews for 30 days with an Orion spacecraft attached. International partners on the program include ESA, the Japan Aerospace Exploration Agency and the Canadian Space Agency.

The outpost is to be located in what is known as a near-rectilinear halo orbit, a highly stable, seven-day orbit ranging from 1,000 mi. to 42,415 mi. from the lunar surface.

The PPE core module, built by Maxar, is a high-power, 60-kW solar-electric-propulsion spacecraft that will provide power, high-rate communications, attitude control and orbital transfer capabilities for the Gateway.  It will be launched connected to the HALO, a pressurized living quarters that includes command-and-control systems and docking ports for visiting spacecraft, including Orion, lunar landers and cargo resupply ships. Northrop Grumman is the prime contractor for the HALO.

In 2021, NASA contracted with SpaceX to launch the combined PPE-HALO into lunar orbit aboard a Falcon Heavy rocket. Launch is planned for no earlier than November 2024. SpaceX also was awarded the first NASA contracts to deliver cargo and other supplies to the Gateway. The agency anticipates one logistics mission will be needed for each crewed increment.

NASA plans to launch the PPE and HALO in time to support the Artemis IV mission, during which astronauts—arriving to the Gateway aboard an Orion capsule—will help integrate the planned International Habitation Module with the HALO. The module will provide additional living space for crews aboard the Gateway.

Depending on the outcome of the Artemis I uncrewed flight test, Artemis II could follow in mid-2024. Four astronauts would launch on what is known as a hybrid free-return trajectory, which uses Earth’s gravity to pull Orion back after flying by the Moon.

The launch will be similar to Artemis I’s through core stage separation. Two burns of the SLS upper stage are planned to adjust Orion’s orbit around Earth, with the spacecraft ending up in an ellipse ranging from 235 mi. to 68,000 mi. above the planet and moving fast enough to leave Earth orbit. The upper stage then separates and becomes a target for a proximity operations demonstration that will assess Orion’s handling qualities in advance of rendezvous, docking and undocking maneuvers in lunar orbit needed for Artemis III.

The Orion service module will conduct the translunar injection burn to send the spacecraft on a four-day trip around the backside of the Moon. The mission is expected to last about 10 days.

For Artemis II, the Orion spacecraft will be equipped with an environmental control and life support system on the capsule, which is not flying on Artemis I. To mitigate the risk, Orion will remain in Earth orbit for two days prior to continuing on to the Moon so the life support system and other equipment can be checked out.

Compared with the first two missions, the Artemis III flight profile is much more complicated, as it requires several SpaceX Starship tanker flights and a fuel depot to provide propellant for the HLS. Artemis III also will require a separate SLS-Orion launch to send the crew to the HLS in lunar orbit.

In total, the OIG estimates NASA will spend $93 billion on the Artemis effort in fiscal 2012-25, a program that so far has bridged political divides both in the White House and in Congress for more than a decade.

“In the past, the programs were largely driven by one political party or another,” says former NASA Administrator Jim Bridenstine.

For example, the 2005-09 Constellation lunar exploration initiative was a Republican-led program. “It never really had buy-in from the Democrats,” Bridenstine says.

Similarly, the Asteroid Redirect Mission, proposed by the administration of then-President Barack Obama in 2013, was panned by Republicans before ultimately proving to be unpopular among both parties. “When only one party is driving the effort, it creates an opportunity for the other party—when things change—to cancel the effort,” Bridenstine says. “We worked really hard to make sure that when we built the Artemis program . . . we were reaching out to Democrats as much as possible. We worked really hard to try to make this as bipartisan as possible.”

Along with building bipartisan political support, NASA added international collaborations, which were not a part of the failed Constellation program. “It makes it more of a sustainable program when all these countries are sharing the costs and gaining the benefits,” Bridenstine says. “That model is how we thought about building the Artemis program.”