I read a book somewhere around 1981 or 82 at our local library. It was the first book in a series. I can almost remember the entire book just not the title nor the author. I would love to find out if the author continued the series.
It starts out that there is a planet of mercenaries who hire out their services to other planets. There is a planetary distress call which recalls all the warriors back to the home planet. One warrior whose starship malfunctions, is left in orbit as the rest of the warriors enter the planets atmosphere and are immediately killed by a extremely lethal radiation weapon that has killed the entire planet.
He was close enough to the planet to become terminally ill, and ends up going out into the universe seeking who sent the bomb in the grain supply and killed his people and to try and find another warrior. On the way, he meets up with a scientist who knows what is going on. They replace his bones through some process to keep him alive.
There is also a creature that reminded me of a ghost. That is all that I remember.