Service module in the context of "Boeing Starliner"

The European Service Module (ESM) is the service module component of the Orion spacecraft, serving as its primary power and propulsion component until it is discarded at the end of each mission. In January 2013, NASA announced that the European Space Agency (ESA) will contribute the service module for Artemis I, based on the ESA's Automated Transfer Vehicle (ATV). It was delivered by Airbus Defence and Space in Bremen, in northern Germany to NASA at the end of 2018. After approval of the first module, the ESA will provide the ESMs from Artemis II to Artemis VI. However, the Trump administration has called for the termination of Orion spacecraft program after Artemis III.

The module's first flight was Artemis I, the first major milestone in NASA's Artemis program to return humans to the Moon, on November 16, 2022. The Space Launch System launched Orion toward the Moon, where the ESM placed the spacecraft into distant retrograde orbit around the Moon, and subsequently extracted it from that orbit and sent it back to Earth.

Dragon 2 is a class of partially reusable spacecraft developed, manufactured, and operated by the American space company SpaceX for flights to the International Space Station (ISS) and private spaceflight missions. The spacecraft, which consists of a reusable space capsule and an expendable trunk module, has two variants: the 4-person Crew Dragon and Cargo Dragon, a replacement for the Dragon 1 cargo capsule. The spacecraft launches atop a Falcon 9 Block 5 rocket, and the capsule returns to Earth through splashdown.

Crew Dragon's primary role is to transport crews to and from the ISS under NASA's Commercial Crew Program, a task handled by the Space Shuttle until it was retired in 2011. It will be joined by Boeing's Starliner in this role when NASA certifies it. Crew Dragon is also used for commercial flights to ISS and other destinations and is expected to be used to transport people to and from Axiom Space's planned space station.