A simplified technical overview of the European Service Module's propulsion system that powers the Orion spacecraft to the Moon and back for Artemis.

A total of 33 engines of three types provide thrust to manoeuvre the spacecraft on all axes.

The main engine on the first mission is a repurposed Space Shuttle Orbital Maneuvering System engine that has flown in space before. This engine provides 25.7 kN, enough to lift a van, and can swivel in pitch and yaw.

Eight thrusters are placed as a backup and provide 490 N each – enough to lift 50 kg on Earth. These are fixed at the bottom of the Service Module to provide orbit corrections and as a backup to the main engine.

Lastly, 24 smaller engines grouped into six pods provide attitude control. In fixed positions, they can be fired individually as needed to move the spacecraft in different directions and rotate it into any position.

The propellant is provided by four 2000-liter tanks with 1-cm thick walls inside the service module: mixed oxides of nitrogen (MON) as oxidiser and monomethyl hydrazine (MMH) as fuel. The tanks will hold the fuel at a pressure of 25 bar with a total capacity of nine tonnes of fuel. Helium from two tanks push the propellants into the engines.

Orion is NASA’s next spacecraft to send humans into space. It is designed to send astronauts farther into space than ever before, beyond the Moon to asteroids and even Mars. When they return to Earth, the astronauts will enter our atmosphere at speeds over 32 000 km/h but the capsule will protect them and ensure a bumpy but safe landing.

ESA has designed and is overseeing the development of Orion’s service module, the part of the spacecraft that supplies air, electricity and propulsion. Much like a train engine pulls passenger carriages and supplies power, the European Service Module will take the Orion capsule to its destination and back.