Apollo: The Race To The Moon

by Catherine Bly Cox

Before each major maneuver, the astronauts went through a straightforward and largely automated procedure. The astronauts would select an appropriate star from their list and ask the spacecraft to find it for them. The spacecraft, consulting the I.M.U., would orient itself so that, if the platform was properly aligned, the star in question would be centered in the cross hairs of the crew’s sextant, the A.O.T. (Alignment Optical Telescope). If the star wasn’t exactly centered, the astronaut looking through the A.O.T. made the necessary adjustment to center it, and the computer entered the adjustment into the I.M.U., which then corrected itself. When the crew of Thirteen tried to do this with the alignment it had borrowed from the C.S.M., they found that the debris from the explosion in the service module still accompanied them, reflecting light and creating a swarm of false stars indistinguishable from the real ones. They reported the problem to the ground. “A genius in Mission Control,” Lovell wrote in his account of Apollo 13, suggested using the sun instead (it was Ken Russell, the lead Guido). Not even the particles from the debris could block out a target as large as the sun.