Space Launch System

The Space Launch System (SLS) is an American two-stage super heavy-lift expendable launch vehicle used by NASA. The primary launch vehicle for the Artemis program, SLS is designed to launch the four-person Orion spacecraft. The rocket first launched in November 2022, carrying the uncrewed Artemis I mission. Its only crewed launch has been for the Artemis II lunar flyby in April 2026, becoming the second launch vehicle to carry humans beyond low Earth orbit (LEO), after NASA's Saturn V of the Apollo program. Development of SLS began in 2011 as a congressionally mandated replacement for the retiring Space Shuttle program and the cancelled Ares I and Ares V launch vehicles of the Constellation program, incorporating some hardware from both programs. Costing US$31.6 billion as of 2025, the project has been criticized for mismanagement, budget overruns, and delays, but ultimately succeeded in human spaceflight in 2026. All SLS launches take place from Launch Complex 39B at the Kennedy Space Center in Florida. The new Boeing-built core stage is powered by four ex-Shuttle RS-25 engines. Attached to the core are two Northrop Grumman five-segment Solid Rocket Boosters, built for the Ares vehicles, tested on Ares I-X, developed from the Shuttle's four-segment SRB. SLS currently uses the Interim Cryogenic Propulsion Stage (ICPS) as its second stage, for the insertions to low Earth orbit and trans-lunar injection. ICPS uses the RL10 engine, and was derived from the Delta Cryogenic Second Stage designed by Japan's space agency. Aerojet Rocketdyne builds the RS-25 and RL10 engines. Starting from Artemis V, no earlier than late 2028, SLS will use the Centaur V upper stage, developed for the Vulcan Centaur, instead of ICPS. NASA previously planned to upgrade SLS from its current Block 1 configuration to a Block 1B and Block 2, but cancelled these plans in February...