Last flight for Craggy

#1 in series. space opera. It was 2095 and Freighter Captain Dixon Cragg, (Craggy to his friends) was unhappy at having to take early retirement at only eighty four. But times were changing and he had to play his part, helping the youngsters take his place. Earth was dying, ravished by war and disease. Moon was a busy place and was the trading post between Earth and Mars.
Convinced he was about to be sent off to Earth, his only alternative seemed to be to work as a toilet cleaner on Moon. But events were unfolding that would change the course of history for ever.