A world-renowned astronomer and an esteemed science writer make the provocative argument for space exploration without astronauts. Human journeys into space fill us with wonder. But the thrill of space travel for astronauts comes at enormous expense and is fraught with peril. As our robot explorers grow more competent, governments and corporations must ask, does our desire to send astronauts to the Moon and Mars justify the cost and danger? Donald Goldsmith and Martin Rees believe that beyond low-Earth orbit, space exploration should proceed without humans. In The End of Astronauts, Gold.