Six days after the space shuttle Columbia was supposed to touch down here at Kennedy Space Center, thousands of workers gathered at the landing site to mourn and remember the fallen crew members.

It was on the same spot that many of them had gathered last Saturday to welcome the crew home.

"They were supposed to return here," Florida Gov. Jeb Bush (R) told the assembly. "After orbiting the Earth for 16 days, after traveling more than 6 million miles, after seeing every corner of our beautiful world, they were supposed to return here. . . . This place stood ready to welcome home seven new heroes last Saturday morning, but the men and women of Columbia did not return to us. Our entire nation grieves at their loss."

Despite the size of the gathering, the informality of the setting on Runway 33 and the clouds that dropped occasional sprinkles, a somber silence prevailed during the hour-long ceremony. Many employees of the space center shed tears amid songs and short speeches offered by local clergy, two astronauts, Robert Crippen and James D. Halsell, Bush and NASA Administrator Sean O'Keefe. Florida Sen. Bill Nelson, a former astronaut, also attended.

"Last Saturday, Columbia and her stalwart crew were minutes away from this port, this very spot in safety following their noble mission to advance the frontiers of science," O'Keefe said. "Friends and family, we were all gathered here at the Shuttle Landing Facility waiting to give these space explorers a welcoming hug for their return to this good Earth, and instead God brought the crew members into his loving embrace. Such are the mysteries of existence that we can never hope to fathom."

There were lighter moments, too, as colleagues and friends recalled the seven astronauts and the shuttle Columbia, which Crippen said was beloved though it was "often bad-mouthed for being a little heavy on the rear end."

Likewise, Rabbi Zvi Konikov of the Chabad Jewish Community Center of the Space Coast recalled a conversation he had with Israeli astronaut Ilan Ramon.

"Last year, Ilan Ramon turned to me with a question," Konikov recalled. " 'How does one mark the Sabbath in space with every 90 minutes another sunset, every 10 1/2 hours is a Sabbath, every 20 days Rosh Hashanah?'

"Jerusalem, we have a problem.

"So I had my homework to do. But Ilan taught us a powerful message: No matter how fast we're going, no matter how important our work, we need to pause and think about why we're here on Earth."

One of the most somber moments came at the ceremony's end, when four NASA T-38s flew overhead in the missing-man formation, in which one of the jets broke off from the pack to fly into the clouds.

"That's what choked me up," said Heri Soto, 36, an engineer on the processing team for the fatal mission. "It shook me. It shook everybody. It suddenly touched home then."