The last time humanity appeared to face a serious military threat from space may have been in 1938, when radio reports of a Martian invasion ignited public panic. While the event turned out to be fiction, part of Orson Welles’ radio drama adaptation of H.G. Wells’ The War of the Worlds, actual space battles are likely to have significant consequences for those of us back on Earth. Unfortunately, the world’s superpowers now find space to be a tantalizing place to plan for combat.