Overview
The Space Launch System (SLS) is NASA's super heavy-lift expendable launch vehicle, developed to support deep-space exploration missions under the Artemis programme. SLS launched successfully for the first time on Artemis I in November 2022, sending the uncrewed Orion capsule around the Moon and back. It is the most powerful rocket to have completed a successful orbital mission, producing 39,144 kN (8.8 million lbf) of thrust at liftoff.
Key Specifications (Block 1)
| Parameter | Value |
|---|---|
| Operator | NASA (prime contractor: Boeing) |
| First Flight | 16 November 2022 (Artemis I) |
| Height | 98.1 m (322 ft) |
| Diameter | 8.4 m (core stage) |
| Liftoff Mass | ~2,608,000 kg |
| Core Stage Engines | 4 × RS-25 (former Shuttle main engines) |
| Solid Rocket Boosters | 2 × 5-segment SRBs (Northrop Grumman) |
| Upper Stage | ICPS (Interim Cryogenic Propulsion Stage, 1 × RL10) |
| Payload to LEO | 95,000 kg |
| Payload to TLI | 27,000 kg |
| Reusability | Fully expendable |
| Launch Site | LC-39B, Kennedy Space Center, Florida |
Block Variants
Block 1: The initial configuration, used for Artemis I and planned for Artemis II. Uses the ICPS upper stage with a single RL10 engine. 27,000 kg to trans-lunar injection (TLI).
Block 1B: Replaces the ICPS with the more powerful Exploration Upper Stage (EUS), featuring four RL10 engines. Increases TLI capacity to ~38,000 kg. Planned for Artemis IV and beyond.
Block 2: A future upgrade with advanced boosters replacing the SRBs, targeting 46,000 kg to TLI and 130,000 kg to LEO. Timeline uncertain.
Artemis I
SLS's maiden flight on 16 November 2022 was a success. The rocket launched the uncrewed Orion capsule on a 25.5-day mission that included a distant retrograde orbit around the Moon, reaching a maximum distance of 432,210 km from Earth — the farthest a human-rated spacecraft has ever travelled. Orion returned safely with a precision splashdown in the Pacific Ocean.
Criticism and Cost
SLS has faced criticism for its high per-launch cost (estimated at $2.2–4.1 billion per mission including manufacturing and operations) and its fully expendable design. Unlike SpaceX's reusable Falcon Heavy and Starship, every SLS core stage, booster set and upper stage is discarded after a single use. Proponents argue SLS is the only currently operational vehicle capable of sending crew-rated payloads to the Moon with Orion.
