page_title: John Houbolt
section_title: Lunar orbit rendezvous (LOR)
hierarchical_section_title: John Houbolt / Lunar orbit rendezvous (LOR)
caption_attribution_description: English: John C. Houbolt at blackboard, showing his space rendezvous concept for lunar landings. Lunar Orbital Rendezvous (LOR) would be used in the Apollo program. Although Houbolt did not invent the idea of LOR, he was the person most responsible for pushing it at NASA.
context_page_description: John Cornelius Houbolt was an aerospace engineer credited with leading the team behind the lunar orbit rendezvous mission mode, a concept that was used to successfully land humans on the Moon and return them to Earth. This flight path was first endorsed by Wernher von Braun in June 1961 and was chosen for Apollo program in early 1962. The critical decision to use LOR was viewed as vital to ensuring that Man reached the Moon by the end of the decade as proposed by President John F. Kennedy. In the process, LOR saved time and billions of dollars by efficiently using existing rocket technology.
context_section_description: Although the basics of the lunar orbit rendezvous (LOR) concept had been expressed as early as 1916 by Yuri Kondratyuk and 1923 by German rocket pioneer Hermann Oberth, NASA would provide the first practical application of the concept. Some engineers were concerned about the risks of space rendezvous, especially in lunar orbit, where there would be no fallback options in case of a major mishap.
  After Houbolt presented the LOR concept to a series of dismissive high-level panels, he ignored the chain of command and complained in a long letter dated November 15, 1961, to Associate Administrator of NASA Robert Seamans that his proposal had been derided as "a scheme that has a 50 percent chance of getting a man to the moon and a 1 percent of getting him back." Indeed, at one of the earliest NASA panels on December 14, 1960, Houbolt was attacked in the presence of both Seamans and Wernher von Braun by fellow engineer Max Faget, who announced, "His figures lie. He doesn't know what he's talking about." However, the detailed letter to Seamans, together with studies of the difficulties posed by the need for a massive rocket in a direct ascent and the problems associated with landing a large craft on the lunar surface following an earth orbit rendezvous, led Seamans and von Braun to support LOR by early 1962.
  While some aspects of Houbolt's initial estimates were off (such as a 10,000 pound Apollo Lunar Module which was ultimately 32,399 lb (14,696 kg)), his LOR package proved to be feasible with a single Saturn V rocket whereas other modes would have required two or more such rocket launches or a rocket much heavier than the Saturn V to lift enough mass into space to complete the mission
caption: LOR explained by Houbolt
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