HOUSTON Its easy to forget that before the 20- and 30-somethings made their mark on the internet, youth was prominent in the U.S. space program.

Most Apollo astronauts were in their late 30s and up, but the engineers and whiz kids running Johnson Space Centers (JSC) Mission Control Center were a young and enthusiastic bunch.

Many were fresh out of college and drawn to the new frontier by President Kennedy. More than a few had military experience.

The Apollo 13 mission was a supreme test of their skills and imagination, taking them beyond putting a man on the moon, to devising a way to bring back a crippled ship and its crew. The answers werent in the books -- theyd have to make up the rules as they went.

Flight director Glynn Lunney (nearest camera), and his team of controllers struggle to bring Apollo 13 safely home.

Lunney and crew swung into action that wouldnt end until splashdown almost one week later.

NASA and JSC management had already gone home after the crews live TV broadcast before the explosion, but rushed back to the space center.

Kranz and Lunney briefed them on the situation and on their plan.

Lunney, now retired and living near Houston, recalls the response was, "How can we help you guys?" A clear course of action was developed.

"It said a lot about NASA and delegation," Lunney said. "They were willing to let a bunch of 30-somethings in the control center decide without interfering."

Retrofire officer Chuck Deiterich was at home when his wife came in and told him shed heard on TV a serious problem had developed with the spacecraft.

He sped to JSC and wound up spending the night developing plans for engine burns to bring the endangered crew home.

Deiterich, then 32, said he didnt have time to think about the situation, but worked with the rest of the controllers to find solutions. To him it felt like another simulation exercise or "sim" conducted by the trainers.

"When you work a sim, it looks and feels like a real mission," he said. "When you get to the real mission you carry the same attitude and dont think too much about the consequences until its over."

Deiterich worked almost all of the Apollo missions and said each one seemed to have their own twist for mission controllers to work on. He calculated an engine burn for Apollo 8 when commander Frank Borman thought the third-stage booster was not falling back after separation. Apollo 12 was struck by lightning after liftoff and now Apollo 13 was in serious danger.

"When the flight was over, we debriefed it. We found out that we didn't need to do anything different and we'd been on the right path. It was a grand thing -- a wonderful piece of work."

Lunney said within eight to 10 hours, Mission Control had a firm plan to bring back the crew safely. In the first few minutes of the crisis, the crew had moved to the lunar module and powered down the command module.

The decision was made to go around the moon, rather than execute a risky burn of the damaged service module engine and go directly back to Earth. Instead, the crew would fire the lunar modules engine. Toward the end of Lunneys shift, worries about the carbon dioxide levels surfaced.

"By the time we got to worrying about it, the back room had already begun work on it," Lunney said.

To Lunney, it seemed more than a Mission Control effort. Other NASA centers, contractors and JSC personnel pitched in.

"We were faced with the most dangerous event in spaceflight history and no one shied away from what they were supposed to do," he said.

Deiterich, retired and living near Austin, Texas, said hes amazed at how people believe computers did all the work in Mission Control during the rescue of Apollo 13. He and others calculated the midcourse-correction, reentry and other engine burns.

"We did stuff with computers and they would do the math for you," he said. "But they didnt come up with the sequences and commands."

Every controller had a desk crammed with notebooks, drawings and charts. A lot of work was still done with pencil and paper, Deiterich said.

"Things werent as automated as they are now," he said.

Hard work and long hours paid off for the crew and Mission Control when the capsule and crew splashed down in the Pacific Ocean. The JSC crew breathed a sigh of relief, but within days was recording what theyd learned and looking at what they could have done differently.

"When the flight was over, we debriefed it," Lunney said. "We found out that we didnt need to do anything different and wed been on the right path. It was a grand thing -- a wonderful piece of work."