Some experts are calling for an international code of conduct for spacefaring nations. But defining misconduct isn't easy.
An analysis by the Union of Concerned Scientists suggests that just about everything that the Air Force's new X-37B robotic space plane can do could be done using cheaper technology.
The US Air Force's secret X-37B space plane remains in Earth orbit, but its initial mission might be coming to an end.
The new national space policy calls on the space agency to target missions beyond low-Earth orbit – such as to an asteroid – by 2025, with the eventual goal of sending astronauts to Mars.
Critics say its motives may have included testing missile defenses or poking at China.