English: Artist concept of the SLS in flight. The SLS is an advanced, heavy-lift rocket that will provide an entirely new capability for science and human exploration beyond Earth’s orbit. The first SLS mission -- Exploration Mission 1 -- in 2017 will launch an uncrewed Orion spacecraft to demonstrate the inteВgrated system performance of the SLS rocket and spacecraft prior to a crewed flight. The second SLS mission, Exploration Mission 2, is targeted for 2021 and will launch Orion and a crew of up to four astronauts.