Silent Autumn

Dane was born on an Earth that was environmentally unsound: the result of industrial pollution that has encompassed the entire planet. He left to become a starship pilot. After a successful career, he returned to the planet of his birth to help his sister settle the estate of his parents, who have recently died. As the book opens, he is departing from Earth for the last time, in order to accept a job as the pilot of a revolutionary new galactic explorer called the GOmod-1 (Galactic Odyssey Model One).
Sandy is an astrophysicist who was born and raised on the Settlements: giant, cylindrical space stations or platforms that occupy Lagrangian points in Earth's orbit. She has discovered a "stellob" - a stellar object - which could possibly be a neutron star in the making.
Dane and Sandy leave the space platform for the new platform being built by Brunel, in the location of the Trojan satellites in the orbit of Jupiter. Here they meet for the first time the genius if somewhat temperamental man of 113 years. Also there to meet them is Sandy's mother, Barbara (also an astrophysicist). Dane, Barbara, and Sandy discuss the interrelationships that are inevitable in a long-lived and sexually free society which condones nothing but insensitivity. People can live in space only by getting along with their fellow man - and woman.
Fred, an engineer now working as Brunel's second in command, explains all that he has done in the past four decades since his last hop - with Dane and Barbara - to a neutron star. He has elected to have a family, all of whom live on the new Settlement. He and Barbara have aged in realtime while Dane - who has spent so much time at faster-than-light speeds - has hardly aged.
Brunel's ego is almost as large as the new space platform he has designed. But more important to him is the new deep space vehicle that he wants Dane to pilot for him. The objective round-trip time to the proto-neutron star that Sandy has discovered is nearly five years, although only a couple months will pass for those on the hop.
Every deep space hop incorporates three people: pilot, astrophysicist, and engineer. Dane thinks that Fred is the most likely candidate as vehicle engineer, since he helped in the construction of the GOmod-1 from its inception. But Brunel has different ideas. He himself has decided to go on the hop, to try out his new toy - and hopefully to prove to the System that he is the greatest engineer in the history of mankind. He wants to be remembered for something more than just building a platform that is bigger than any previous platform.
What the trio discover on the other side of the Galaxy will have far-reaching implications for the entire human race. Their discovery will - hopefully - enable mankind to survive the next stage in the expansion of civilization.