"In the space race of the 1950s and '60s, the leading voices were rocket scientist Wernher von Braun and ... another guy. Household names included Neil Armstrong, Alan Shepard and ... oh, you know, the fellow who pushed the idea of a separate crew capsule and lunar lander. America wouldn't have won the race, the Eagle wouldn't have landed in 1969 and the Apollo 13 crew would never have survived if it weren't for an engineer from [the] NASA Langley Research Center. John C. Houbolt."

So reads a feature on HamptonRoads.com written in 2009 about one of the unsung heroes of the Apollo Program. Houbolt may have never become a household name, but his ideas and contributions to Apollo made it possible to achieve the goal of landing a crew on the Moon and safely returning them by the end of the decade.

As a member of of Lunar Mission Steering Group, Houbolt had been studying various technical aspects of space rendezvous since 1959 and was convinced, like several others at Langley, that lunar-orbit rendezvous (LOR) was not only the most feasible way to make it to the moon before the decade was out, it was the only way.

At the time many scientists thought the only way to achieve a lunar landing was to either build a giant rocket twice the size of the Saturn V (the concept was called Nova) or to launch multiple Saturn Vs to assemble the lunar ship in Earth orbit (an approach known as Earth orbit rendezvous).

In November 1961, Houbolt took the bold step of skipping proper channels and writing a 9-page private letter directly to incoming Associate Administrator Dr. Robert C. Seamans. Describing himself somewhat melodramatically "as a voice in the wilderness," Houbolt protested LOR's exclusion from the NASA debate on the Apollo mission profile.

"Do we want to go to the moon or not?" the Langley engineer asked. "Why is Nova, with its ponderous size simply just accepted, and why is a much less grandiose scheme involving rendezvous ostracized or put on the defensive? I fully realize that contacting you in this manner is somewhat unorthodox," Houbolt admitted, "but the issues at stake are crucial enough to us all that an unusual course is warranted."

Houbolt clearly saw that the giant Nova rocket and the expensive and complex Earth orbit rendezvous plan were clearly not a realistic option--especially if the mission was to be accomplished anywhere close to President Kennedy's timetable.

While conducting a rendezvous in orbit around the Moon was going to be a challenge, the weight, cost and savings of using LOR were obvious once one realized that LOR was not fundamentally much more difficult than Earth orbit rendezvous. This insights, and Houbolt's brave and energetic advocacy of it, made all the difference.

Dr John C. Houbolt, so little known, but a man of great ideas and bravery, died April 15, 2014, at the age of 95.