How does the Orion spacecraft fit into the Artemis missions & the Human Landing System (HLS)? Our interest in the Orion spaceship stems from its interfaces & dependencies with the HLS & the Lunar Gateway. 

The Orion spacecraft will support the Artemis program in returning Humans to the Moon. Its purpose is to transfer the crew (four crew members) to & back from the Lunar Gateway during the Artemis II & III missions. SpaceX’s HLS (or BLUE ORIGIN‘s) will be required to dock into the Gateway, orbiting in Near Rectilinear Halo Orbit (NRHO). The Orion will either dock to the Gateway, from which the crew will have access to the HLS, or dock into SpaceX‘s / Blue Origin HLS for direct crew access. Two of Orion’s crew will land on the Moon aboard the HLS, and two will remain in orbit onboard Orion or the Gateway. SpaceX has the option to demonstrate a safe, independent crew transfer to the lunar orbit; however, the Orion will still function as NASA’s & the international community’s gateway crew circulation and cargo delivery vehicle. 

The Orion is designed for a 25-34 days mission timeline with 21 days active lifetime limit.

The Orion Vehicle, at a wet Mass of 27 Ton @ pre-TLI (Trans Lunar Injection), will be mounted & launched into orbit on the SLS (Space Launch System). 120 sec from liftoff, the SLS will release the two SRBs (Solid Rocket Booster). Shortly after, the Orion separates from the LVSA (Launch Vehicle Stage Adapter) & jettisons the LAS (Launch Abort System). Then Orion and the ICPS ( Interim Cryogenic Propulsion Stage) will coast into apogee, & as it starts cruising, the Orion spacecraft will deploy its four solar arrays. After several orbital maneuvers around the earth, the ICPS will perform the TLI, then disconnect from the Orion along with the Module Stage Adapter (MSA), sending the Orion spacecraft into a translunar patched trajectory to catch up with the Gateway at NRHO.

The Orion Vehicle – the Crew Module and the European Service Module (ESM) – is 7.3 meters in height & 5.3 meters in diameter. 

The ESM holds 33 engines divided into three types: The main engine is a repurposed Space Shuttle Orbiting Maneuvering System engine (OMS-E) capable of providing 25.7 kN. Another eight auxiliary Aerojet R4D-11 provide 490 N each. Lastly, 24 Reaction Control 22N Engines, grouped into six pods to provide attitude control.

The ESM also includes 4x2000l propellant tanks, two with Mixed oxides of Nitrogen (MON) and two with monomethyl hydrazine capable of carrying 9 tons of fuel. It also has hydrogen tanks to push the fuel to the engines, two water tanks (240 liters – for a 20-day mission with four astronauts ), nitrogen tanks (30kg), and oxygen tanks (90kg). The whole ESM is protected from space by six radiators and multi-layer insulation blankets and cooled by hydrofluoroether pumped in a closed circuit.