An anonymous reader quotes a report from Space.com: The first flight of NASA's next-generation heavy-lift rocket, the Space Launch System (SLS), is now scheduled for 2019 and will not include a human crew, agency officials said today (May 12). As of 2016, NASA had planned for the SLS' first flight to take place in 2018, without a crew on board. But the transition team that the Trump administration sent to the agency earlier this year asked for an internal evaluation of the possibility of launching a crew atop the SLS inside the agency's Orion space capsule. Robert Lightfoot, NASA's acting administrator, said during a news conference today that, based on the results of this internal evaluation, a crewed flight would be "technically feasible," but the agency will proceed with its initial plan to make the rocket's first flight uncrewed. The internal evaluation "really reaffirmed that the baseline plan we had in place was the best way for us to go," Lightfoot said. "We have a good handle on how that uncrewed mission will actually help [the first crewed mission of SLS] be a safer mission when we put crew on there." SLS' first flight will be called Exploration Mission 1, or EM-1, and will send an uncrewed Orion capsule (which has already made one uncrewed test flight, aboard a United Launch Alliance Delta IV Heavy rocket) on a roughly three-week trip around the moon. The first crewed flight, EM-2, was originally scheduled to follow in 2021.