The primary contractor for NASA’s Space Launch System (SLS), Boeing is nearing the completion of the first SLS Core Stage. NASA hopes to launch the maiden flight of the SLS rocket this year.

Boeing has recently confirmed that the top half of the first SLS Core Stage has been assembled in a vertical stacking frame at the Michoud Assembly Facility in New Orleans. The so-called “forward join” is made of the intertank and the liquid oxygen (LOX) propellant tank.

The SLS Core Stage is made up of five parts. The first is the engine section within which the four RS-25 engines are mounted. The engine section also houses the aft booster attachment points. Atop the engine section is the 2-million-litre (537,000-gallon) LH2 propellant tank. The LH2 tank is then separated from the 742,000-litre (196,000-gallon) LOX propellant tank above by the intertank. The intertank houses avionics, electronics and the forward booster mounting points. Finally, above the LOX propellant tank sits the forward skirt housing the flight computer, cameras and avionics.

With the “forward join” of the first stage complete, Boeing is currently completing the installation of plumbing and electronics in the engine section. Once complete, the section will be mated with the huge LH2 tank and then transported to the Michoud Assembly Facility for final assembly.

Once complete, the SLS Core Stage will be mated with Boeing’s Interim Cryogenic Propulsion Stage (ICPS) and Alliant Techsystems five-segment Solid Rocket Boosters (SRBs), an upgraded variant of the SRBs used for the shuttle. The ICPS will only be used for Block 1 test flights. Once operational, the rocket will utilise the Exploration Upper Stage (EUS) currently being developed by Boeing.

With the completion of the first SLS Core Stage approaching, Boeing has begun construction on the propellant tanks for the second.