The EM-3 flight has gained its first notional mission outline, detailing a flight to Near-Rectilinear Halo Orbit to deploy the Hab module for the new Deep Space Gateway.
According to the preliminary mission outline, the EM-3 flight would be a crewed mission to Near-Rectilinear Halo Orbit (NRHO) around the Moon. Placing the DSG in a NRHO will create a DSG orbital trajectory that takes the outpost close to the lunar surface to permit low-energy transfer opportunities for scientific excursions in cislunar space and to the lunar surface itself.
For EM-3 specifically, the mission carries a total duration of 16-26 days with baseline objectives to “demonstrate spacecraft systems performance beyond LEO for crewed flight” and to launch the DSG habitat module to NRHO and mate the Hab to the already-launched Power and Propulsion Element (PPE).
The PPE will have been launched on the previous SLS mission, EM-2.
To accomplish these objectives, both the crewed Orion module and the Hab element for the DSG will launch atop an SLS Block 1B rocket as co-manifested payloads from the Kennedy Space Center, Florida.
SLS will launch into a 28.5 degree inclination orbit, with SLS’s SRBs and Core Stage inserting Orion and the Hab module into an initial 22 x 970 nautical mile (40.7 x 1,806 km) orbit.
Following this initial orbit insertion, the nominal mission timeline would call for the EUS to perform an ascent burn to circularize the Orion and Hab module into an 100 nmi (115 miles; 185 km).
The EUS will then fire its engines again for the Trans-Lunar Injection burn, which will send Orion, the EUS, and the Hab module into a transfer orbit to the Moon.
Once safely en route to the Moon, Orion will separate from the top of the remaining SLS stack and will likely turn around to mate to the Hab module.
The exact details of this are not yet known as the design process for the DSG continues.
Regardless, over the course of the 3-10 day outward trip from Earth to the Moon, Orion’s auxiliary engines will perform at least four Outbound Trajectory Correction (OTC) maneuvers to refine the craft’s approach to the Moon.
These OTCs will allow Orion/Hab to target a precise point to enter a NRHO around the Moon while the EUS performs a disposal into a heliocentric orbit.
Once Orion and the Hab module have slipped into a NRHO, Orion will maneuver the Hab toward the PPE, and the four-person crew will then connect the two DSG elements together – a moment that will begin in-space construction of the DSG.
Once the Hab module and PPE are successfully mated together, Orion’s crew will perform a series of initial checkout operations over Orion’s 10-20 day stay in NHRO.
After this, Orion will undock from the Hab element and baby DSG, and the journey back to Earth will begin.
As with the outbound trip, the inbound journey will last between 3-10 days, with Orion’s auxiliary engines performing several Return Trajectory Corrections (RTCs) to properly align the craft for a precise point in Earth’s atmosphere for reentry.
According to graphics on the preliminary mission plan, EM-3 will target a splashdown in the Pacific Ocean off the coast of Baja California, Mexico – after which Orion will be loaded onto a recovery ship and brought back to the United States via the Port of San Diego.
Source: Nasaspaceflight.com