Background

The Space Launch System successfully launched Artemis II on 1 April 2026, placing the Orion capsule and four crew members on a translunar trajectory for the first crewed Moon mission in over fifty years. The Block 1 variant used for Artemis II produces 8.8 million pounds of thrust at liftoff, making it the most powerful rocket NASA has ever flown.

SLS is a government-owned heavy-lift launch vehicle derived largely from Space Shuttle hardware: its core stage uses four RS-25 engines (former shuttle main engines) and TWIN solid rocket boosters. Each flight costs approximately $4 billion all-in. In February 2026, NASA Administrator Jared Isaacman cancelled the planned Block 1B and Block 2 upgrades, freezing SLS capability at its current configuration. Congress responded by mandating $1.025 billion per year in SLS funding through FY2029, preventing any near-term programme cancellation.

SLS sits at the centre of a cost-versus-capability debate. SpaceX Starship, if it achieves full operational status, could offer higher payload capacity at a fraction of the cost, undermining the political and industrial rationale for continuing SLS beyond the legislated missions.

Common Questions

How powerful is the Space Launch System?

SLS Block 1 produces 8.8 million pounds of thrust at liftoff, making it the most powerful rocket NASA has ever flown, surpassing the Saturn V in some metrics.Source: NASA technical specifications

Why does the SLS cost so much?

Each SLS/Orion flight costs ~$4 billion due to the use of expendable hardware, shuttle-derived engines produced at low rates, and the overhead of maintaining a government-run launch infrastructure.Source: NASA OIG cost analysis

Is the SLS being cancelled?

Not immediately. Congress legislated $1.025 billion per year through FY2029. However, the Block 1B and Block 2 upgrades were cancelled in February 2026.Source: One Big Beautiful Bill Act; NASA statements

How does SLS compare to SpaceX Starship?

SLS costs ~$4 billion per flight and flies once every one to two years. Starship aims for full reusability at a fraction of the cost, though it is not yet operational for crewed missions.Source: Industry analysis

What is the SLS Block 1B?

Block 1B was a planned upgrade adding an Exploration Upper Stage for greater payload capacity. It was cancelled by NASA Administrator Isaacman in February 2026.Source: NASA programme announcement, Feb 2026

How the World Sees Them

China

SLS cost and limited flight rate are cited as evidence that the US cannot sustain a competitive lunar programme pace against China's Long March 10.

United States

Congressional mandates protect SLS jobs in key states; the rocket's political constituency is stronger than its economic case.

European Union

ESA's service module depends on SLS continuing; European contractors benefit from each flight even at the high per-mission cost.