"Turnover Point" by Alfred Coppel
"Every era in history has had its Pop Ganlon's. Along in years and not successful and not caring much anyway. A matter of living out their years, following an obscure path to oblivion.
It was that way in ancient Egypt, just as it will be when the Solar System shrinks to our size. And once in a while such men are given an opportunity to contribute to the society that has forgotten them...."
Let'Em Breathe Space by Lester Del Rey
"Eighteen men and two women in the closed world of a space ship for five months can only spell tension and trouble—but in this case, the atmosphere was literally poisoned."