Slower-than-light interstellar travel became physically possible, and five expeditions were launched, manned by star-peering low-mass wireheads. Ultra-long baseline interferometry, beamed from radiotelescopes aboard the wirehead starships, established hard parallaxes for most stars in the Orion Arm of the Galaxy. Examinations of the Perseus and Centaurus Arms showed troubling patches where patterns of stars appeared to have an ominous regularity.