This article looks at how international humanitarian law may apply to military operations in space. Though the laws of war are well established on earth, space poses new challenges to the principles of distinction, proportionality and precaution in attack. Future scenarios whereby operations might be directed against moon-based objects, or where military astronauts might be deployed into space raise further questions as to how these principles should apply. By considering the laws of war as they are enforced on earth, and through engagement with academic opinion, this article seeks to understand the level of protection provided by the law when applied to this new domain. In anticipation of official clarification, this approach leads to reasoned arguments for reform in key areas. The challenges posed are addressed through both a contemporary and a future lens. Broad conclusions that the law of armed conflict does not shift seamlessly into space are strengthened by the numerous anomalies that ensue.