Space may offer hope for the future of humanity in the form of unexplored resources and scientific secrets, but humanity has only begun to scratch the surface of this frontier. In the 2020s, space science is being driven less by scientific exploration and more by tech company entrepreneurs, who are changing the way that space science develops and evolves. This issue of The Reference Shelf looks at the state of space exploration in the 21st century and explores a variety of views about how space science and exploration could and should evolve in the future.