The Mote in God's Eye

By Larry Niven and Jerry Pournelle. Simon and Schuster, New York, 1974. ISBN 0-671-21833-6 <bibref>Niven.etal:1974</bibref>

This is a science fiction story about humanity's first contact with alien intelligence about 1000 years after attaining faster-than-light travel. The aliens contact humanity by sending a piloted laser sail to an inhabited human world.