If you were at the controls of a spacecraft attempting to land on the moon you wanted the sun behind you at an angle between seven and twelve degrees above the horizon, so it cast long shadows from boulders you might not see otherwise. This means that you were aimed at a crescent moon when you launched from Earth three days before. The first landing on Apollo 11, for instance, blasted off toward a new quarter-moon and the crew saw no more than a three-quarter Earth.

It wasn't until the last Apollo mission that NASA targeted a landing site on the far western face of the moon: the rumpled Valley of Taurus Littrow, which earthly geologists thought might be the least disturbed and thus primordial of the possible landing sites. This meant launching toward a nearly full moon, which in turn meant departing from Florida at night. It was the only night launch of the mighty Saturn V, the most stupendous rocket ever built, and took place on December 7, 1972.

The three men atop the rocket were Eugene Cernan, the Commander of Apollo 17; Harrison "Jack" Schmitt, the Lunar Module Pilot who would accompany Cernan down to the surface if all went well; and Ron Evans, the Command Module Pilot who would remain in lunar orbit, keeping their return ship running while his crewmates did the glamorous exploring. All three have claimed that they took the famous Blue Marble Shot.

On the five previous Apollo missions the commanders, all space veterans, were allowed to choose who would land with them on an alien world. All had picked rookies, loyal sidekicks they felt comfortable with and confident in. For Apollo 17 Cernan had chosen Joe Engle, a former X-15 pilot, and the two trained for months as the backups for Apollo 14. Then by established NASA policy they rotated together to prime crew status on Apollo 17.

But then Congress canceled the funding for Apollo 18, which also had a crew that trained together for months. The Lunar Module Pilot on that crew was Jack Schmitt, a Harvard-trained geologist who was a scientist-astronaut. Six of them were selected amid great nerdy fanfare in 1965 but none had been assigned to a mission until Schmitt got a seat on the very last planned flight. They were generally regarded as dorks by the pilot astronauts, Right Stuff bravos like Cernan and Engle who between them had flown a hundred different aircraft, from helicopters to rocket planes, landing on everything from heaving carriers to empty deserts. When political pressure bumped Engle in favor of Schmitt on Apollo 17 a very odd couple was sent to the moon.

They were busy as hell the first six hours. Lunar missions only made two orbits around the earth, three hours of frantic preparation before cranking it up to escape velocity. They were coming around to the daylight side for the third time when the last booster fired for six minutes to propel them away from the human planet. There were a thousand critical things they had to do next: separate from that final booster stage, accomplish a delicate docking maneuver with the service module, reorient and stabilize their new combined spacecraft, check all the various systems and compute their trajectory, and climb out of the awkward hardsuits they'd been wearing since blast-off.