Ares V in the context of Earth Departure Stage

The Artemis program is a Moon exploration program led by the United States' National Aeronautics and Space Administration (NASA), formally established in 2017 via Space Policy Directive 1. The program is intended to reestablish a human presence on the Moon for the first time since the Apollo 17 mission in 1972, with a stated long-term goal of establishing a permanent base on the Moon. This will facilitate human missions to Mars.

Two principal elements of the Artemis program are derived from the now-cancelled Constellation program: the Orion spacecraft (with the ESM instead of a US-built service module) and the Space Launch System's (SLS) solid rocket boosters (originally developed for the Ares V). Other elements of the program, such as the Lunar Gateway space station and the Human Landing System, are in development by government space agencies and private spaceflight companies, collaborations bound by the Artemis Accords and governmental contracts.

The Space Launch System (SLS) is an American super heavy-lift expendable launch vehicle used by NASA. As the primary launch vehicle of the Artemis Moon landing program, SLS is designed to launch the crewed Orion spacecraft on a trans-lunar trajectory. SLS first launched on 16 November 2022 for the uncrewed Artemis I mission.

Development of SLS began in 2011 as a replacement for the retiring Space Shuttle and the canceled Ares I and Ares V launch vehicles. SLS was built using a combination of Shuttle components, including solid rocket boosters and RS-25 engines, and new technology such as the Core Stage. The project has seen mismanagement, budget overruns, and delays. The first launch, required by Congress to take place by 2016, occurred nearly six years later.

The Constellation program (abbreviated CxP) was a crewed spaceflight program developed by NASA, the space agency of the United States, from 2005 to 2009. The major goals of the program, in which no crewed missions flew before its cancellation, were "completion of the International Space Station" and a "return to the Moon no later than 2020" with a crewed flight to the planet Mars as the ultimate goal. The program's logo reflected the three stages of the program: the Earth (ISS), the Moon, and finally Mars—while the Mars goal also found expression in the name given to the program's booster rockets: Ares (the Greek equivalent of the Roman god Mars). The technological aims of the program included the regaining of significant astronaut experience beyond low Earth orbit and the development of technologies necessary to enable sustained human presence on other planetary bodies.

Constellation began in response to the goals laid out in the Vision for Space Exploration under NASA Administrator Sean O'Keefe and President George W. Bush. O'Keefe's successor, Michael D. Griffin, ordered a complete review, termed the Exploration Systems Architecture Study, which reshaped how NASA would pursue the goals laid out in the Vision for Space Exploration, and its findings were formalized by the NASA Authorization Act of 2005. The Act directed NASA to "develop a sustained human presence on the Moon, including a robust precursor program to promote exploration, science, commerce and US preeminence in space, and as a stepping stone to future exploration of Mars and other destinations." Work began on this revised Constellation Program, to send astronauts first to the International Space Station, then to the Moon, and then to Mars and beyond.

The RS-68 (Rocket System-68) was a liquid-fuel rocket engine that used liquid hydrogen (LH₂) and liquid oxygen (LOX) as propellants in a gas-generator cycle. It was the largest hydrogen-fueled rocket engine ever flown.

Designed and manufactured in the United States by Rocketdyne (later Pratt & Whitney Rocketdyne and Aerojet Rocketdyne). Development started in the 1990s with the goal of producing a simpler, less costly, heavy-lift engine for the Delta IV launch system. Two versions of the engine have been produced: the original RS-68 and the improved RS-68A. A third version, the RS-68B, was planned for the National Aeronautics and Space Administration's (NASA) Ares V rocket before the cancellation of the rocket and the Constellation Program in 2010.