Not all world-class choreographers design for principal dancers of the American Ballet Theater or the Marinsky Ballet, both known for extreme perfectionism; some, who are actually engineers, work with astronauts underwater to choreograph spacewalks, also known as EVAs.

"As we approach the 20th anniversary of the first Hubble Servicing Mission later this year, we need to tell our 'formula for success' story before it is forgotten," says Mike Weiss, then the deputy technical program manager for the Hubble Space Telescope and now the Laser Communications Relay Demonstration (LCRD) mission project manager, who was there from the beginning.

The stage was set when the Solar Maximum Mission (SolarMax), which launched on Feb. 14, 1980, to study the sun during high periods of the solar cycle, developed a show-stopping malfunction.

SolarMax blew a fuse. "The challenge was to figure out how to repair SolarMax using shuttle-based, space-walking astronauts to allow our scientists to observe the next period of solar maximum activity, which occurs only once every 11 years, without spending funds to design, build and launch a new solar observatory," explains Weiss.

Engineers from Goddard met with their counterparts at NASA's Johnson Space Center in Houston to brainstorm. NASA, in general, is an agency of perfectionists, but where spacewalks are concerned, NASA practices as frequently and diligently as any principal dancer preparing for an international competition.

Astronauts prepare for spacewalks in Johnson's Weightless Environmental Training Facility (WETF), the predecessor to today's Neutral Buoyancy Laboratory (NBL).

Because movement under water is as close as possible to approaching that of zero-gravity, astronauts had long prepared for spacewalks in Johnson's Weightless Environmental Training Facility (WETF), the predecessor to today's Neutral Buoyancy Laboratory (NBL).

The standard approach to problem-solving spacewalk issues was for the astronauts to don training versions of their spacesuits and dive into the pool with their scuba-diving assistants. Design engineers and other training assistants observed the training runs deck side. The astronauts trained for SolarMax repair by working with a mockup of the spacecraft, which was an almost exact duplicate.

"It just wasn't working efficiently," says Weiss. "The engineers felt too disconnected from the trainers. We couldn't get a feel for how things were really going underwater." During a training session, Ken Rosette, a Goddard design engineer, came up with a brilliantly elegant solution: The spacecraft engineers could learn to scuba dive so that they could work underwater next to the astronauts. Their project manager, Frank Cepollina, thoroughly endorsed the idea.

About a dozen engineers prepared for their new starring roles as scuba divers by becoming certified. Once they dove into the water, they understood how the tools and equipment they were designing for the complex spacecraft operated in a zero-G environment.

"Working in the water alongside the astronauts and being able to observe and assist with the underwater training made all the difference in quickly finding the correct solutions," says Weiss. It was the beginning of an incredible partnership between Goddard's spacecraft experts and Johnson's shuttle experts and astronauts.

A few years passed. On April 24, 1990, Hubble launched on STS-31 to be NASA's preeminent eyes in the sky. Then came major disappointment. Hubble couldn't focus. Hubble needed corrective glasses to correct flaws in the mirror design.

The scuba-diving engineers were again called in to rehearse with the astronauts. The life-size mockups of Hubble were large, so the underwater training began in Marshall Space Flight Center's Neutral Buoyancy Simulator (NBS), which was NASA's deepest tank. The team began preparing for a then unprecedented five spacewalks to repair an even more complicated spacecraft.

"Very late one evening, Story Musgrave and his three space-walking crewmates arrived at the NBS to meet the engineering team," recalls Weiss. "Story immediately said he had some ideas he wanted to try. We told him that we were all set for the morning run, but Story wanted us to put on our scuba gear and immediately get to work. So we did."

The servicing mission, launched in December of 1993 on STS-61, was an unqualified success, as were the subsequent four encores known as Servicing Missions 2, 3A, 3B and 4.

"Once the engineers learned how to scuba dive into the pool with the astronauts, the game changed," says Weiss. "SolarMax was the beginning, but Hubble really changed the game.

"Our work led not only to marvelous scientific discoveries, but it also definitively demonstrated NASA's ability to successfully perform on-orbit servicing missions." Scuba-diving engineers were later used to train for assembly of the International Space Station. They remain ready to help with a future mission to take NASA even farther into space.