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In the summer of 1961, NASA was seriously considering the particulars of getting to the Moon by the end of the decade. One of the first questions on everyone’s mind was: “How do we actually get to and from the Moon?” Serious consideration was given to 3 options or mission modes: direct ascent, Earth-orbit rendezvous, and Lunar-orbit rendezvous. Direct ascent required the development of a single huge rocket booster that could land on the Moon and return. NASA realized that this plan would be enormously expensive and the rocket could not be developed within the decade. NASA focused on the concept of Earth-orbit rendezvous (EOR). The main idea of EOR was to launch several spacecraft independently on mid-sized Saturn rockets. The astronauts would then assemble, fuel, and detach a lunar mission vehicle from the joined modules and fly directly to the Moon. Many NASA leaders strongly supported this idea, particularly the concept of creating a space station of sorts. However, a few engineers were strong believers in the concept of lunar orbit rendezvous. The concept was suggested by engineer Tom Dolan and was largely ignored until it was strongly championed by Langley engineer, John Houbolt. The proposal used a larger Saturn rocket to carry a pair of smaller spacecraft to lunar orbit. One of them would ferry part of the crew to and from the lunar surface. In the days before orbital rendezvous had even been tried, the idea of rendezvous operations far away in lunar orbit was considered dangerous and impractical. Within a year though the decision had been made. On July 11, 1962, Administrator James Webb announced that NASA’s Apollo Program would land on the Moon using the lunar orbit rendezvous method.

[Picture: Apollo 11 Lunar Module as photographed by Michael Collins, the Command Module pilot]

The then-radical supercritical wing looks amazing on this NASA F-8 in this picture from the early 1970s. But, Richard Whitcomb's breakthrough is now incorporated in most new aircraft designs.

On this day in 2006, NASA Astronauts Piers Sellers and Mike Fossum (of the STS-121 crew) performed an Extravehicular Activity (EVA, as we say at NASA) - or spacewalk - to deploy a spare pump module and to replace a reel of cable responsible for running power, among other things, to the International Space Station's Mobile Transporter Cart. This EVA, which lasted for 6 hours and 47 minutes, brought the mobile cart back into full operation.

Training for EVAs is a long and arduous process. Astronauts must learn how to maneuver and perform tasks in a 280-pound spacesuit without gravity to hold them in place. This is more difficult than you might think - and as NASA discovered during Project Gemini in the 1960s. In order to prepare astronaut for spacewalks, NASA built the Neutral Buoyancy Lab (aka the NBL). Located at the Johnson Space Center (in Houston, Texas), the NBL is a 40-ft-deep pool filled with 6.2 million gallons of water. Resting at the bottom of this pool (the largest in the world) are full-sized models of various parts of the International Space Station. (The real station is much too large to fit in a pool this size.)

Astronauts begin training by going through their planned spacewalks while wearing normal scuba gear. Once each astronaut is comfortable performing assigned tasks underwater, they don their bulky spacesuit. Scuba divers are also stationed in the pool for preliminary assistance and protection. Each astronaut usually train 7 hours for every hour planned in their EVA, giving them lots of experience before they even step outside the ISS.

[Picture: EVA training at NBL on October 7, 1997]