The Tranquillity Alternative

On mankind's last mission to the moon, a killer comes along for the ride
Since the first manned spaceflight in 1944, NASA has conquered the outer atmosphere, explored Mars, and placed nuclear missiles on the moon. But funding for interstellar adventures—military or otherwise—has dried up. Now, NASA is planning a final lunar mission to pack up the remnants of man's first extraterrestrial colony. The nuclear missiles are meant to be shot into the sun, but someone onboard the USS Conestoga would prefer to see them fired toward Earth.
The night before the mission launch, one of the astronauts is kidnapped from his hotel room and replaced with a surgically altered body double. By the time the other astronauts uncover the deception, the Conestoga is too far from home for NASA to help. On the surface of the Moon, a decades-old conspiracy has reached its final stage, and Earth's fate hangs in the balance.