High Quality Content by WIKIPEDIA articles! 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. It is to be upgraded over time with more powerful versions. Its initial capability of the core elements, without an upper stage, will be between 70 metric tons (for the Block 0 configuration with 3 engines and a partially fueled core) and 100 metric tons (for the Block I configuration with 4 engines and a fully fueled core) to low-Earth orbit (LEO) in preparation for missions beyond low-Earth orbit. With the addition of an integrated upper Earth Departure Stage and a fifth SSME-derived core engine, the total lift capability is to be 130 metric tons which would make it the most powerful rocket ever created.