KENNEDY SPACE CENTER — It is called the missing-man formation, and it is a military aviator’s way of saying good-bye.

The maneuver is executed by four low-flying fighters in a tight, triangular formation. At the appropriate moment, one of the middle planes climbs so steeply that it is almost vertical. The other three fighters continue on, holding their positions. The now-open hole in the formation represents a comrade who didn’t return home.

On Friday morning, the missing-man formation was performed above the barren, wind-swept runway at the Kennedy Space Center’s shuttle landing facility. Directly over the end of the runway, a middle plane went vertical. The jet climbed thousands of feet in a few seconds, disappearing through the single blue hole in what had all morning been a dark, cold and rain-swollen sky.

The other three planes rumbled forward hauntingly, the hole in the formation honoring the space shuttle Columbia, which should have landed on that very runway six days before.

Standing on the runway were Gov. Jeb Bush, NASA officials and religious leaders. Joining them were about 5,000 mourners who had come to pay a solemn tribute to the crew that didn’t come home.

“They were supposed to return here,” Bush said. “After orbiting the Earth for 16 days, after traveling more than six million miles, after seeing every corner of our beautiful world, they were supposed to return here.”

Bush spoke of the pride Floridians feel for the space industry. He said the entire country is sharing the burden of the disaster with the people who work around the space center.

“And so, men and women of the Kennedy Space Center, let us grieve together, but let us also share hope,” Bush said. “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. Let us cherish the hope that those men and women we lost will inspire us and our children for generations to come.”

Bush was joined at the ceremony by NASA administrator Sean O’Keefe, who was appointed to the position by President George W. Bush. O’Keefe called the space center a port for the great ships of modern history.

“Throughout our family here at Kennedy … our rivers of tears flow,” O’Keefe said. “It was our fervent prayer that Columbia and its crew would safely come home to its harbor here, but that was not to be the case. But please know this: Do not lose heart. The families of the astronauts, the American public and the president have all expressed deep confidence.”

O’Keefe said people will again fly into space from the Center. He thanked the employees for the way they handled the tragedy.

“We know space flight has risk, but on Saturday when our worst fears were realized, the people of this center were focused, organized and deliberate, doing so well what we’ve all been trained to do so many times,” O’Keefe said. “Like the rest of the NASA family, we will persevere.”

Possibly the most emotional speech of the ceremony was given by Bob Crippen. Along with John Young, Crippen piloted Columbia into space in 1981 on the shuttle program’s maiden voyage. Crippen also commanded the Challenger space shuttle on three separate missions, the last one barely a year before it exploded during liftoff.

Crippen spoke of the lost crew. But he also spoke of the Columbia itself, which he said had made 27 visits to space before its final, devastating trip.

“Columbia was a fine ship,” Crippen said. “Columbia was hardly a thing of beauty, except for those of us who loved and cared for her. She was often bad-mouthed for being a little heavy in the rear end, but many of us can relate to that.”

Because of that weight, Crippen said, Columbia didn’t get the glamorous space-station missions. Instead, he said, Columbia often went up on scientific missions focused on “giving us a better life here on Earth.”

“Just as her crew has, Columbia has left us quite a legacy,” Crippen said.

Friday’s memorial was part of a week of mourning for the lost astronauts. Earlier in the week, memorials were held in Houston and Washington D.C. Saturday, a memorial was held in Lufkin, Texas, at the center of Columbia’s debris field.

As NASA continues to grieve, the work of finding out what happened to the orbiter continues. Thousands of pieces of debris have been collected. Speculation Sunday turned toward a possible ice buildup on the outside of the shuttle.

In addition, NASA is analyzing a radar image taken a day after Columbia’s launch. The image apparently shows debris separating from the shuttle.

One week following the accident, NASA is acknowledging its speculation and second-guessing. The agency knows that the left wing was the cause of the problems, but work remains to determine what caused the damage.

The workers and friends who tearfully walked from the shuttle’s runway Friday are left with the task of moving forward. Gov. Bush said the United States will continue to pursue the promise of space.

“This nation under God still looks heavenward, looking no longer for the return of those whom we have lost but to God himself,” Bush said.