The year is 2183. Fifty-six-year-old Saunders Maxwell is a stubborn old space-farer who has spent his entire life in space. He has commanded the Moon-Mars shuttle and led exploration missions beyond Mars. Later he turned to asteroid mining, captaining a small ship and crew on repeated trips to the asteroid belt, bringing back minerals or even small asteroids to sell so that the Mars colony could harvest them for the needed resources.
As he and his pilot Harry Nickerson fly over the vast slopes of the giant volcano Olympus Mons on their way home from one such mining mission, Maxwell spots a strange glint below, a glint that is not natural and should not be there.
When they land they discover something entirely unexpected and impossible, the body of man who had disappeared on a distant asteroid almost a half century before. Sanford Addiono had been on one of the first manned missions to the asteroid belt when he and a partner had vanished. Nothing was ever heard from them again. Even more baffling, two later missions to that asteroid found that it had disappeared as well, no longer in orbit where it was supposed to be.
Now, 46 years later, Maxwell finds Addiono’s body on the surface of Mars. How Addiono had gotten to Mars from a distant lost asteroid–without a spaceship–was baffling.
That riddle was magnified by what Addiono had brought back with him. Among his effects was a six-fingered robot hand that had clearly been made by some alien civilization, along with a recorder and memo book describing what Addiono had seen.
Here was a mystery that would rock humanity, the first alien contact. And at that moment Saunders Maxwell decides that he is going to be the person to solve that mystery, even if it takes him through hell and back.
Unfortunately, that is exactly where that journey takes him.
The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.
He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.