Artist concept of the SLS Block 1 configuration. For the first time in almost 40 years, a NASA human-rated rocket has completed all steps needed to clear a critical design review (CDR). The agency’s Space Launch System (SLS) is the first vehicle designed to meet the challenges of the journey to Mars and the first exploration class rocket since the Saturn V. SLS will be the most powerful rocket ever built and, with the agency’s Orion spacecraft, will launch America into a new era of exploration to destinations beyond Earth’s orbit.