The Forever Man — Gordon R. Dickson

The ancient starship La Chasse Gallerie is found drifting perilously in space. Despite heavy damage from alien Laagi warships, incredibly the ship is till intact and the voice of its pilot, Raoul Penard, comes through loud and clear. But Petard died over one hundred years ago On Earth, frantic investigation reveals that Petard may be dead but his mind is very much alive merged with the ship itself. The staggering potential of this evolutionary breakthrough compels the scientists to embark on a technological journey of astonishing discovery