Manned flight to Mars

This is one of my favorite books, chronicles a different story. What would have happened if instead of building the Space Shuttle, the Americans had decided to focus all their efforts on a manned flight to Mars, continuing the Apollo / Saturn program?
There would have been triumphs and tragedies, but the story would have had a completely different course. This is what happened forever inaccessible and lost who visited us with talent by Stephen Baxter. We will probably on Mars, but by a much longer way.