Artemis

Artemis, U.S. crewed spaceflight program begun in 2017 that is intended to return astronauts to the Moon during the 2020s for the first time since 1972. Artemis is named after the Greek Moon goddess, the twin sister of the god Apollo, for whom the previous American crewed lunar spaceflight program was named.

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Artemis emerged from the canceled Constellation program, which would have carried astronauts to the International Space Station (ISS) after the space shuttle program ended. It represents the United States’ most ambitious space exploration endeavour since the National Aeronautics and Space Administration (NASA) last sent astronauts into space aboard the space shuttle in 2011. (Since then, NASA astronauts have flown on Russian Soyuz spacecraft and the commercially built SpaceX Dragon spacecraft.)

Although the Constellation program was canceled by the administration of U.S. Pres. Barack Obama in 2010 because of what was determined to be an unrealistic launch schedule, work continued on the crewed spacecraft Orion. Ultimately, Orion became part of the Artemis lunar exploration program proposed by the Donald Trump administration.

Orion consists of a cone-shaped crew module, which can carry four astronauts. The crew module is connected to a cylindrical service module, which has Orion’s main engine and carries water and air, as well as four solar arrays to power the spacecraft. The service module, built by the European Space Agency (ESA), is based on the Automated Transfer Vehicle (ATV), an uncrewed spacecraft that supplied the ISS. Orion had its first uncrewed test flight in December 2014, completing two orbits of Earth.

Artemis I on its launchpad

In 2010 the U.S. Congress mandated the development of a new launcher to carry Orion. The Space Launch System (SLS) is one of the largest and most powerful rockets ever built. Its central stage is powered by four liquid-hydrogen–liquid-oxygen engines. Flanking the central stage are two solid rocket boosters that would fall away two minutes after launch. The central stage would then carry Orion to Earth orbit. SLS weighs 2.6 million kg (5.74 million pounds) when fully fueled and has a maximum thrust of 39 million newtons (8.8 million pounds). (For comparison, the Saturn V, which launched the Apollo astronauts toward the Moon, weighed 2.8 million kg (6.2 million pounds) when fully fueled and had a thrust of 34.5 million newtons [7.6 million pounds].)

The SLS was originally planned to be operational at the end of 2017 at a cost of $500 million per launch. However, development of the SLS went significantly over budget, and, in a 2021 report, the NASA inspector general estimated that the true cost per launch of the SLS would be $2.2 billion, which meant that each Artemis launch would cost more than $4 billion when the cost of Orion was included.

Artemis I launch

Orion spacecraft

The goal of the Artemis I mission, which launched on November 16, 2022, is to test the safety and performance in deep space of the uncrewed Orion, which would orbit the Moon about 70,000 km (44,000 miles) from its surface on a flight expected to last about 25.5 days. The return of astronauts to space as part of a NASA program would then happen as early as 2024, when Artemis II would take a crew of four around the far side of the Moon and back to Earth. If both missions are successful, Americans would again set foot on the lunar surface as part of Artemis III, planned for launch in 2025. As part of the Artemis III mission, two astronauts would transfer to a SpaceX Starship waiting in lunar orbit, which would carry them to the lunar surface. Those astronauts, whom NASA has said would be the first woman and the first person of colour on the Moon, would spend almost a week in the Moon’s south polar region, where frozen water possibly exists in permanently shadowed craters. This represents a significant departure from the Apollo missions on which astronauts explored the equatorial regions of the Moon.

Orion approaching Gateway.

Future Artemis missions would dock at Gateway, an international space station in lunar orbit from which astronauts would descend to the Moon’s surface. Gateway’s first two modules, the Power and Propulsion Element (PPE) and the Habitation and Logistics Outpost (HALO), are scheduled to be launched together, uncrewed, in 2024. The ESA would build an International Habitation module (I-HAB), with contributions from the Japan Aerospace Exploration Agency, and a refueling module for Gateway. In addition, the Canadian Space Agency would supply an external robotic arm for the space station. Proposed lunar surface missions in the Artemis program include building a base camp at the lunar south pole, where astronauts could stay for one or two months.