These scientists made history in their Grumman "clean room."

BETHPAGE, N.Y. - John Devaney and his colleagues weren't exactly sure what Neil Armstrong would set foot on when he climbed down the ladder of the lunar module to the surface of the moon.

"We didn't know what the moon was made of," recalled the retired Grumman engineer, one of the thousands who helped make the module that landed on the moon 40 years ago tomorrow.

"Guys were writing us letters, MBAs, saying the astronauts are going to sink up to their waists in 5 or 6 feet of moon dust," he said. "I always point out to people that Armstrong hung onto the ladder and he took his one foot off and then made his speech."

The men who built a dozen lunar modules at a Long Island defense plant better known for making jet fighters were somewhat bashful about their place in history.

"We didn't realize the significance at the time," said Devaney, now 74. "We knew it was important, blah blah blah, but later on it became more important."

After winning a contract in 1962, nearly 3,000 engineers and more than 7,000 people in all created more than a dozen hand-built lunar modules at a cost of about $2 billion, keeping President John F. Kennedy's vow to put a man on the lunar surface by the end of the decade.

Because it was designed solely to fly in space after hitching a ride aboard a massive Saturn rocket, the lunar module, or LEM, was made of lightweight materials. No seats were necessary, because the astronauts didn't have to worry about gravity. An early design featured large windows, but engineers downsized the view for astronauts to mere portals.

"Every one of these LEMs that landed on the moon was different," said Gerry Sandler, 75, who worked intimately on many aspects of the project and retired as president of Grumman Data Systems. Later models left room for a lunar rover - think golf cart in space - and more space for toting hundreds of pounds of moon rocks back to Earth.

Sandler believes that Grumman, now a part of Northrop Grumman Aerospace Industries, was chosen to build the lunar module because of its expertise making planes to land on aircraft carriers. The F-14 Tomcat of Top Gun movie fame was a Grumman aircraft.

"They knew how to build small structures and landing gear that got knocked around, and that was what was needed to land on the moon," Sandler said.

The lunar module was actually two spaceships in one. The bottom, or descent stage, with the spidery legs, got the astronauts to the lunar surface. The top part, or ascent stage, featured a small rocket ship that ferried two astronauts back to the orbiting command module where one astronaut stayed behind.

Devaney who worked in systems analysis and technical support, remembered how much precision was required in a time before modern computers.

"The whole engineering was done with slide rules," he said, noting the lunar module's entire computer capability was less than what's in today's average cell phone. "Someone would have to go over all the daily notes and calculations every night."

It took several years of designing and redesigning before actual construction began in Grumman's "clean room," where everyone had to wear pristine white coveralls, hats, and boots to prevent any contamination of the spacecraft. A piece of dust in the wrong place could spark disaster.

"It was one big room, no dividers. And it was wall-to-wall desks and people and noise. I mean, everybody trying to do his little thing," said Devaney of Plant 25, where the LEM was built.

There were unending discussions on how to balance the weight of the aircraft, debates on how engines would work, and a litany of other concerns.

At the nearby Cradle of Aviation Museum in Garden City, N.Y., which houses LM-13, one of three lunar modules built but never launched after the Apollo project fell victim to budget cuts, former test pilot and Grumman retiree Tom Gwynne said visitors often tell him of a family connection to the project; a father or uncle who may have built the tiniest widget somewhere on the spacecraft.

"Everybody who worked on this took responsibility for it," Gwynne said.

Al Contessa was 19 when he was hired as a thermal insulation technician - applying the material that looks like aluminum foil on the LEM. It was paper-thin because gravity was not an issue.

Only days before Apollo 11 took off, Contessa was sent to Cape Kennedy to add insulation to the lower portion of the lunar module's landing gear, climbing inside the massive Saturn rocket as it awaited liftoff. "It was pretty hectic right up until the very end," Contessa, now 62, remembered.