Although NASA has made progress toward the overall space exploration science priorities recommended in a 2011 decadal survey by the National Academies of Sciences, Engineering, and Medicine, the space agency should raise the priority of scientific research that addresses the risks and unknowns of human space exploration. This heightened priority is particularly important given the limited remaining lifetime of the International Space Station (ISS) – the most significant destination for microgravity research – and because the U.S. currently does not have a strategy for the station beyond 2024, says a new midterm assessment report by the National Academies.