How We Got to the Moon

During the 1960s, NASA had the daunting task of landing a person on the moon. When John F. Kennedy announced the goal to put a man on the moon by the end of the decade, they had only recently sent Alan Shepard into space for the first time. It would be another nine months before John Glenn would become the first American to orbit the Earth. NASA would need to perfect every step in just 8 short years. The first step is to reach the altitude of the moon. In order to get there efficiently, we must perform a maneuver known as a “Hohmann Transfer.” Designed to minimize fuel consumption, it allows us to build lighter, cheaper spacecrafts.
But once the spacecraft is headed to the moon, it will be going too fast to be fully captured by the moon’s gravity. At this speed, it will slingshot around it and head back to Earth. To insert itself into lunar orbit, the spaceship needs to slow down. The only way it can do this is by burning its rocket in the direction it’s flying. Once it’s burned for long enough, the speed of the rocket is low enough to establish a lunar orbit.
moon 2
moon Both the US and the USSR had been trying to refine this technique since the late 1950s, with little success. Both nations had succeeded in getting impactors and landers onto the moon, but it wasn’t until November 1966 when NASA successfully put an unmanned craft into orbit. In December 1968, Apollo 8 would become the first manned spaceship to orbit the Earth.
Getting to lunar orbit was tricky, but once NASA engineers could consistently make the calculations correctly, they advanced to the next challenge – getting a manned lander onto the surface of the moon.

The USSR’s Luna 2, the first manmade
to reach the surface of the moon.
Image Credit: NASA

Written by Scott Yarbrough