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Space Shuttle OMS Engine
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Space Shuttle OMS Engine

Shuttle-era engine reused in Orion's service module, flying its seventh mission.

Last refreshed: 2 April 2026 · Appears in 1 active topic

Key Question

How does a Space Shuttle engine end up powering a Moon mission?

Timeline for Space Shuttle OMS Engine

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Common Questions
What engine powers Orion to the Moon?
The Orbital Maneuvering System Engine (OMS-E), a refurbished Space Shuttle engine now in ESA's service module.Source: Lowdown briefing analysis
How many times has the Artemis II OMS engine flown?
Six previous flights on the Space Shuttle; Artemis II is its seventh mission.Source: Lowdown briefing analysis
Why is Artemis using old shuttle engines?
Reusing proven hardware reduces cost and risk compared to developing a new engine; the OMS-E has an extensive reliability record.Source: Lowdown briefing analysis

Background

The Orbital Maneuvering System Engine (OMS-E) that powers Orion's trans-lunar injection burn on Artemis II flew six Space Shuttle missions in the 1990s and 2000s before being refurbished for deep-space duty. The engine is now mounted in the European Service Module 2, making it the propulsive heart of the first crewed mission beyond Earth orbit since Apollo 17.

The OMS-E was originally developed by Aerojet for the Space Shuttle programme, providing the thrust needed for orbital insertion and de-orbit. Its vacuum-optimised nozzle and reliability record made it a logical candidate for reuse rather than developing a new engine under cost and schedule pressure.

Reusing shuttle-era hardware in a 21st-century Moon mission reflects both the enduring quality of 1970s-era aerospace engineering and the budgetary constraints that have shaped Artemis throughout its development. The engine's seventh mission will be its most ambitious: a burn that sends four humans toward the Moon for the first time in over half a century.