NASA’s Space Launch System: Enabler for Deep Space Exploration

NASA’s SLS (Space Launch System) rocket is a super-heavy lift launch vehicle. Its current primary use is to launch crew and payloads to the Moon under the NASA-led Artemis campaign. Artemis’s goal is to return astronauts to the Moon, test technologies on the lunar surface and in lunar orbit, and prepare for crewed missions to Mars.

SLS has an initial mass-to-translunar injection (TLI) single launch capability of 59,000 lbs. (27 metric tons [t]) in crewed configuration with NASA’s Orion spacecraft. The vehicle produces 8.8 million pounds (39,100 kN) of thrust.

The single-launch payload capability increases significantly to more than 84,000 lbs. (38 t) on the fourth launch, which debuts the more powerful Block 1B variant featuring the larger, more capable exploration upper stage (EUS). The vehicle can send an Orion spacecraft and crew of four, along with a 10-t co-manifested payload, to the Moon on the same launch. Block 1B can also fly in a cargo-only configuration with a mass-to-TLI capability of 93,000 lbs. (42 t).

On Artemis V, the second flight of the Block 1B variant, new-production RS-25 liquid hydrogen (LH2)/liquid oxygen (LOX) engines will begin flying. The RS-25 was a key propulsion system on the space shuttle. Sixteen engines left over at the end of the Space Shuttle Program were outfitted for SLS and are flying the first four flights of the rocket. The new production engines, which take advantage of modern manufacturing technologies, will produce more thrust than the heritage engines but cost 30 percent less to produce.

The ninth SLS flight will debut the Block 2 variant, featuring more powerful solid rocket boosters. Overall vehicle thrust will increase from the Block 1B’s 8.84 million pounds (39,300 kN) to Block 2’s 9.44 million pounds (42,000kN). Booster performance increases from 3.6 million pounds (16,014 kN) each to 4.2 million pounds (18,683 kN). Mass-to-TLI in crewed configuration increases to 95,000 lbs. (43 t) in a single launch and 101,000 lbs. (46 t) in cargo-only configuration.

As SLS continues moving from development to operation, steps to increase its sustainability are already being implemented. Lessons learned from the building of the first flight vehicle have significantly reduced the build time of the second unit. Beginning with the Artemis III rocket, core stage basic structures will continue to be manufactured at NASA’s Michoud Assembly Facility in New Orleans. The core stage engine section will be outfitted at NASA’s Kennedy Space Center in Florida, and then mated with the remaining 4/5 of the stage shipped from Michoud. The four RS-25 engines also will be installed at Kennedy. This process modification enables more hardware to be in-flow at Michoud while final outfitting of the core stage is completed at the launch site.