Old Man in a Spacesuit - Martian Dreams, #1

As a candidate for First Man on Mars, Harry Burton-HB to his friends-is pretty much the wrong stuff. He's old, his knees creak, and psychologically he's somewhat fragile. An invitation to attend an interview at the astronaut training centre in Cologne is obviously a mistake, and HB ignores it. But the emails keep on coming. HB used to write science fiction, he was famous, until his wife died and depression set in.
Now, though, there's a familiar stirring deep in the recesses of his mind. What would it be like to train as an ESA astronaut for a Mars mission? After all, this is what he used to write stories about. Okay, so somebody in recruitment screwed up. If he can't be an astronaut, at least he'll get to see the look on the recruiters' faces, when he, a sorry old sack of brittle bones and neuroses, washes up on the space agency's doorstep.
Well, surprise. It turns out they're happy to see him. And he's not the only unlikely recruit, because ESA is convinced there is a logic to sending old people to Mars. Throughout training, HB discovers a rekindling of his old passion for space, even though he knows it's nothing more than fund-raising ballyhoo. Except is it? The whole preposterous Mars enterprise is getting serious, gathering pace, and might yet turn out to be more than mere politics and posturing.
It might just happen.