About 15,000 people work at the Kennedy Space Center, and CBS News Correspondent Peter King reports it appeared as if every one of them attended the memorial service at the end of Runway 33.
Dark clouds loomed during most of the hour-long service. But as it closed with an aerial missing-man formation, the T-38 jet that broke away found one of the few holes in the clouds and flew out of sight. Moments later, the hole closed.
The hour-long ceremony at Kennedy Space Center was held in the same area where the astronauts' families had gathered before the shuttle's scheduled landing time last Saturday. Sixteen minutes before it was to land, Columbia broke apart in the skies high over Texas.
"Many said she was old and past her prime. Still, she had only lived barely a quarter of her design life," Columbia's first pilot on the maiden voyage in 1981, Robert Crippen, said with a tear in his voice.
Astronaut Jim Halsell said knowing the Columbia astronauts was and will always be one of his greatest treasures.
"Thank you for gracing our lives with your love and your friendship," he said.
"We miss them more than words can describe," O'Keefe said from a stage that bore a large logo for the mission, STS-107.
The service was open to the 15,000 workers at the space center, and more than 5,000 attended, officials said.
"On Saturday, when our worst fears were realized, the people of this center were focused," O'Keefe said. "The teamwork that was displayed was simply magnificent."
The ceremony began with musical tributes to the seven crew members. Others attending included Sen. Bill Nelson, a former astronaut, and Gov. Jeb Bush.
"Let us share the hope that when we look to the stars, we will see in them a reminder of the heroes who dared to travel among them," Bush said.
Richard Khoury, a NASA transportation worker, said the service would allow workers to grieve publicly.
"This is good because it's hands-on. It lets us feel like we're part of it," said Khoury, who was worked at the center for 19 years.
Other services have been held in Houston and Washington.
Many of the Kennedy Space Center workers were involved intimately in launching Columbia and got to know the seven crew members. The center's 30 mental health workers began interviewing workers this week for signs of post-traumatic stress.
About 150 workers are helping with the investigation, which has focused on several possible sources of the breakup but settled on nothing as the primary cause of Columbia's destruction.