About an hour into the mission, SLS EM (Exploration Mission) 1 is well under way. Shown here is an Orion/ESM (European Service Module) still mated to ICPS, which is burning its last fuel reserves during the end phase of TLI (Trans Lunar Injection)
Here's a short description of what would be going on in the cockpit of Orion/ESM, still mated to the Interim Cryogenic Propulsion Stage (ICPS). The main ICPS engine has just finished the TLI (Trans Lunar Injection) burn and it is on its way to the Moon:
- The orbital apogee has been reached at 353870 km, at which point (when reached) the spacecraft will be in the Lunar gravitational sphere of influence.
- Apogee is graphically represented on MFD as a solid dot.
- Spacecraft is still very close to earth, represented by a diamond symbol on MFD, "only" 3446 km above Earth, and still has a long way to go to reach the Moon.
- During the burn, 2 guidance events made sure that the spacecraft kept pointing along the velocity vector, which was constantly changing as the orbital path was being "stretched" to reach to the Moon.
- During the burn, almost all of the ICPS's fuel was spent, with only 2% remaining. Being the "interim" stage, it is designed to only carry Orion/ESM, without any additional hardware, and as such, it is able to only barely reach the Moon. Currently in development by NASA/Boeing is Exploration Upper Stage (EUS), which will be capable of carrying substantially more load to cislunar space.
The next event would be to detach ICPS from Orion/ESM. ICPS would slowly coast away from Orion/ESM, but still following a generally same trajectory to the Moon, where it would eventually crash onto the Lunar surface, or miss the Moon and enter orbital path around the Sun, much like Saturn S-IVB stages of Apollo era.