John Houbolt

• 1. Introduction

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  John Cornelius Houbolt was an aerospace engineer who once opened a letter to a NASA administrator with an unusual line. 'Somewhat as a voice in the wilderness, I would like to pass on a few thoughts,' he wrote. He was not a lone crank shouting into the void. Houbolt was fighting for an idea NASA's own leadership had already rejected, a plan for reaching the Moon that he called lunar orbit rendezvous. Why did NASA's engineers resist his idea so fiercely at first? What eventually changed their minds? And what happened two decades later, when Houbolt raised a second alarm inside NASA, this time about a very different spacecraft?

• 2. The Lunar Rendezvous Fight

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  On the 14th of December 1960, at one of NASA's earliest review panels, engineer Max Faget turned on Houbolt. Two of the agency's most senior figures watched: Associate Administrator Robert Seamans and rocket designer Wernher von Braun. 'His figures lie,' Faget said. 'He doesn't know what he's talking about.' Houbolt was proposing lunar orbit rendezvous. In his plan, one spacecraft would separate from the main ship in lunar orbit and descend to the surface alone. It would then climb back up to meet the ship still circling overhead.

  Roughly a year later, on the 15th of November 1961, Houbolt wrote a long letter straight to Seamans, ignoring the normal chain of command. In it, he complained that his proposal had been derided. Critics called it a scheme with 'a 50 percent chance of getting a man to the moon and a 1 percent of getting him back.' The same letter posed a blunt question to NASA's leadership: 'Do we want to go to the moon or not?'

  The idea of a lunar orbit rendezvous was not new. Yuri Kondratyuk had outlined the basic concept as early as 1916. German rocket pioneer Hermann Oberth described a version of it again in 1923. NASA, though, would be the first to actually attempt it. Some engineers worried about the risk of any rendezvous in space. A botched docking above the Moon would leave no way to rescue the crew.

  Some of Houbolt's own numbers were off. He initially estimated the Apollo Lunar Module at about 10,000 pounds. The finished module weighed 32,399 pounds, or about 14,696 kilograms. Even so, his overall plan held up. A single Saturn V rocket could fly the lunar orbit rendezvous mission. A direct ascent to the Moon would have needed a much heavier rocket instead. An Earth orbit rendezvous approach would have needed two or more separate Saturn V launches.

  NASA formally adopted lunar orbit rendezvous for the Apollo program in July 1962. Seamans and von Braun came around to support the plan that same year. Houbolt's letter helped persuade them. So did separate studies of the risks posed by a massive direct ascent rocket, and by landing a large craft after an Earth orbit rendezvous. NASA treated the choice as vital to reaching the Moon within President Kennedy's timeline for the decade. It also saved the agency time and billions of dollars by making full use of rocket and spacecraft technology that already existed.

  On the day Apollo 11 landed on the Moon, Houbolt sat in Mission Control as a guest. Von Braun had personally invited him to witness it. As the landing succeeded, von Braun turned to Houbolt and said two words: 'Thank you, John.' A NASA film crew in Houston captured the moment on camera.

• 3. From Iowa To Langley

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  Houbolt was born in Altoona, Iowa, on the 10th of April 1919, the son of first-generation Dutch immigrant parents. He spent part of his childhood in Joliet, Illinois, where he attended Joliet Central High School and then Joliet Junior College.

  At the University of Illinois at Urbana-Champaign, Houbolt earned a bachelor's degree in 1940 and a master's degree in 1942, both in civil engineering. A doctorate in technical sciences followed in 1957, from ETH Zurich.

  Houbolt joined the National Advisory Committee for Aeronautics in 1942. He remained on staff when the agency became NASA. From 1963 to 1976, he worked outside the agency, at a consulting firm called Aeronautics Research Associates. He then returned to NASA and stayed until his retirement in 1985. Throughout much of that career, he worked as an engineer at Langley Research Center in Hampton, Virginia.

  Once NASA committed to lunar orbit rendezvous, many other aspects of the Apollo mission were built around that single decision. Houbolt would apply the same engineering judgment again nearly two decades later, this time to the Space Shuttle.

• 4. The Space Shuttle Warning

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  Ahead of the Space Shuttle's first flight, STS-1, in 1981, Houbolt co-wrote a letter with structural engineer Holt Ashley. It went to Chris Kraft, director of Johnson Space Center. The two engineers urged Kraft to delay the launch. They warned that the orbiter could suffer a major loss of thermal protection tiles, and potentially be lost entirely.

  Their sharpest worry was the strut attaching the orbiter's nose to its External Tank. Langley Research Center pushed for further wind tunnel testing. Kraft agreed to it, though reluctantly. Concern about the tiles was not new; it had persisted since the Shuttle's original development. By that point, though, the teams involved believed the vehicle was safe to fly.

  Upon jettisoning, the External Tank did show heat damage around the forward strut area, just as Houbolt and Ashley had feared. Once in orbit, some tiles were visibly missing near the Shuttle's tail. NASA feared that more critical tiles on the underside might be damaged too. Engineers hastily arranged to use KH-11 KENNEN spy satellites and the Kuiper Airborne Observatory to photograph the orbiter and assess the damage. The damage turned out to be minimal, and the mission concluded safely.

  Similar leading edge thermal protection panels failed years later, this time on the left wing under far more extreme heat. That failure caused the loss of the Space Shuttle Columbia in 2003.

• 5. Honors And Final Years

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  NASA awarded Houbolt its Exceptional Scientific Achievement Medal in 1963. He later became a member of the National Academy of Engineering.

  On the 15th of May 2005, the University of Illinois at Urbana-Champaign granted him an honorary doctorate. His papers were later deposited in the university's archives. In 2009, the Illinois House of Representatives adopted House Resolution 540 in his honor.

  In the 1998 HBO miniseries From the Earth to the Moon, actor Reed Birney played Houbolt on screen. Houbolt himself lived for a time in Williamsburg, Virginia, and later settled in Scarborough, Maine. He died there on the 15th of April 2014, at a nursing home, from Parkinson's disease.

  The city of Joliet, Illinois, where Houbolt had gone to school, commemorated him in several ways. The street fronting Joliet Junior College was renamed Houbolt Road. A mural inside Joliet Union Station includes a Lunar Module, a nod to his work for NASA. A wing of the Joliet Area Historical Museum keeps a permanent exhibit on his achievements.