 This is a question I'm asked fairly often. Why did Apollo go to the moon using lunar orbit rendezvous? The short answer is that it saved weight. The long answer is actually really interesting, and we're going to go through the Colesnodes version today on Vintage Space. When Kennedy pledged the nation to land a man on the moon and return him safely to the Earth on May 25th of 1961, it lit the fire under NASA to really get the Apollo program going, but it didn't tell NASA exactly how to get to the moon. There were few options, the most direct and straightforward of which was a method called direct ascent. This method called for launching a spacecraft directly from the Earth's moon without stopping in either Earth or lunar orbit, launching it on a massive nova rocket. The problem with this method was that the spacecraft was really, really heavy. If it was all going to land on the lunar surface, that meant the crew had to take all of their consumables, including all of the fuel for the return journey, down to the lunar surface and launch it up again. This meant that the payload NASA would have to land on the moon was roughly the size and weight of an Atlas rocket, and it would have to be done such that the crew would be able to ready the spacecraft for launch and launch it from the lunar surface without ground crews. Not only was it heavy, it was actually pretty complicated for the most direct method. Direct ascent fell out of favor as a lunar mission method or mode fairly quickly and was replaced by Earth orbit rendezvous. This method is also pretty much what it sounds like. Rather than launch the spacecraft on one massive nova rocket, Earth orbit rendezvous called for launching the spacecraft in pieces on the smaller Saturn V rocket. Once all the pieces were in lunar orbit, the crew could assemble them and then carry on to the moon. The rest of the mission would basically look like the direct ascent method. The entire spacecraft, including all the fuel for the return journey, would land and launch again from the lunar surface. This method was sort of simpler, but really kind of just made things more complicated. It's still called for landing an incredibly heavy payload on the moon, but now it added the complication of assembling that spacecraft in orbit around the Earth. It was John Hubble, assistant chief of the Dynamics Load Division at NASA's Langley Research Center, who proposed an alternative that was more complicated but would solve the weight issue. His method was called lunar orbit rendezvous. He solved the biggest problem in both direct descent and Earth orbit rendezvous as the size and weight of the payload that had to land on the moon. If landing the fuel for the mission on the lunar surface and then launching it back up again was the biggest challenge, why not leave the fuel in orbit around the moon and pick it up before you return to the Earth? Hubble proposed a modular spacecraft, each piece of which would have a very specific purpose and could be jettisoned when it was done. The entire spacecraft could go to the moon and then only a dedicated smaller lunar landing vehicle would descend to the surface. Descend to the moon with the smaller lunar module and leave the heavier command service module with the fuel for the return journey in lunar orbit. Hubble championed hard for lunar orbit rendezvous, arguing that it was the only way NASA was going to make it to the moon by the end of the decade. The key decision makers behind Apollo eventually came around and the method was selected in July of 1962. However, Earth orbit rendezvous and direct descent using NOVA were both retained as backup methods until October. It wasn't until October of 1962, a year and a half after Kennedy initially pledged the nation to land a man on the moon that NASA figured out exactly how it was going to do it. What do you think might have happened had we gone with direct descent and built the massive NOVA rocket? Let me know in the comments below and if you have questions or topics you'd like to see covered on future episodes, leave that in the comments below as well. For old timey space content every single day of the week, follow me on Twitter as AST Vintage Space. And with episodes going up every Tuesday and Friday, be sure to subscribe right here so you never miss an episode.