Rocket engine

RS-25

Also known as SSME, Space Shuttle Main Engine

Rockets

Overview

A reusable fuel-rich staged-combustion LH2/LOX engine developed for the Space Shuttle (as the SSME) and now expended on the SLS core stage; among the highest-efficiency hydrogen engines flown.

Components & hardware

Propellants

LH2 / LOX

Powers

Space Launch System (SLS)

Knowledge connections

Sources

Facts on this topic will be cited from these primary and reference sources.

NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.

Quick facts

Type: Rocket engine
Cycle: Staged combustion
Propellant: LH2 / LOX
Sea-level thrust: 1,860 kN
Vacuum thrust: 2,279 kN
Specific impulse (vac): 452 s

Unknown specifications are left blank rather than estimated.

Provenance & sources

review 2026.1

Asteria Scientific Review Process · verification: sourced · accurate

High evidenceconfirmed
The RS-25 is a reusable fuel-rich staged-combustion LH2/LOX engine developed as the Space Shuttle Main Engine and now used on the SLS core stage, with a vacuum specific impulse of about 452 seconds.
Source: NASA Science · Public domain (US Government work)

Reviewed by the internal Asteria Scientific Review Process — not an external institutional review. See the evidence framework and authority dashboard.

Quality & authority

56%

Reviewed

Completeness: Complete
Source coverage: Partial
Citation coverage: Complete
Relationship coverage: Complete
Review coverage: Complete
Image coverage: None

Curated from authoritative public sources. See source quality.

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