The Space Launch System, or SLS, is a United States Space Shuttle-derived heavy launch vehicle being designed by NASA. It follows the cancellation of the Constellation Program, and is to replace the retired Space Shuttle. The NASA Authorization Act of 2010 envisions the transformation of the Ares I and Ares V vehicle designs into a single launch vehicle usable for both crew and cargo.

The SLS launch vehicle is to be upgraded over time with more powerful versions. Its initial version without an upper stage is to lift a payload of 70 metric tons to orbit. The final version with an integrated upper Earth Departure Stage is to lift 130 metric tons, which would make it the most powerful rocket ever created.

SLS is to take astronauts and hardware to such destinations as near-Earth objects like asteroids, Lagrangian points, the Moon, and Mars. SLS may also support trips to the International Space Station, if necessary. The SLS Program is integrated with NASA's Orion Program, providing a multipurpose crew vehicle. SLS will use the ground operations and launch facilities at NASA's Kennedy Space Centre, Florida.

On July 25, the SLS program passed two key reviews, for combined system definition and system requirements, to move toward its preliminary design review, scheduled for late 2013. The SLS critical design review is scheduled for early 2014. These various checkpoints pave the way for the finished design of SLS to begin construction in earnest.