NASA is ready to move forward with the development of the Space Launch System (SLS) -- an advanced heavy-lift launch vehicle that will provide an entirely new national capability for human exploration beyond Earth's orbit. It will use a liquid hydrogen and liquid oxygen propulsion system, which will include the RS-25D/E engine from the Space Shuttle Program for the core stage and the J-2X engine for the upper stage. SLS will also use solid rocket boosters for the initial development flights. The SLS will have an initial lift capacity of 77 tons. The lift capacity will be evolvable to more than 143 tons. The first developmental flight is targeted for the end of 2017. By comparison, the Saturn V booster that sent men to the moon was able to lift 130 tons.