The Fated Sky (Lady Astronaut Universe #2)

The Fated Sky continued the grand sweep of alternate history begun in The Calculating Stars. It is 1961, and the International Aerospace Coalition has established a colony on the moon. Elma York, the noted Lady Astronaut, is working on rotation, flying shuttles on the moon and returning regularly to Earth.
But humanity must get a foothold on Mars. The first exploratory mission is being planned, and none of the women astronauts is on the crew list. The international Aerospace Coalition has grave reservations about sending their "Lady Astronauts" on such a dangerous mission. The problem with that is the need for midjourney navigation calculations. The new electronic computation machines are not reliable and not easily programmed. It might be okay for a backup, but there will have to be a human computer on board. And all the computers are women.