(Probably Found) Looking for a book

[trenga]

I am engaged in a book search for a novel of which I cannot remember either the title or author. The story concerns a future where deep space freighters using light speed and atomic engines deliver cargo to the future. The ships are crewed by humans who are physically altered by the atomic drives of the ships and are nursed by female beings called "pooh bears". The central theme of the story is the conflicts caused by having to travel across time, and the isolation of the crews from the rest of humanity. It seems odd, I know, that I can remember so much of the story but cannot remember the title or author. If anyone can put me on the track of this book I wold surely appreciate it. Thanks.

 

[Danny McG]

An old query.
I have a faint tickle about Marion Zimmer Bradley but that's all my memory brings up.
Hoping you still get a notification about this, good luck in your search.

 

[CassFrank]

I suspect Danny McG was on to something and this is Marion Zimmer Bradley’s Endless Universe.

 

[Danny McG]

It looks like you got it @CassFrank

I've now downloaded Endless Universe and here's a quote-
"continually mothered and tended by the Poohbears"

(However I don't think trenga will ever return to confirm this)

 

[Pyan]

I’ll mark it “probably found”, as the ‘poohbears’ attribute seems fairly conclusive.