1989’s Starfarers is the first volume in Vonda N. McIntyre’s Starfarers Quartet.
The near approach of a cosmic string1 offers humanity superluminal access to Tau Ceti. A light-sail spaceship can hitchhike on the string to explore the nearest star system. A consortium of nations builds the Starfarer as a traveling university, one that will send back dividends of new knowledge that will more than pay for its creation.
That is, if it is allowed to do what it is designed to do. Some of its government supporters have other notions of best use.