Shuttle crew honoured at memorial

President Bush led the United States in mourning the seven space shuttle Columbia astronauts yesterday, telling family and friends at a memorial service that the nation shared in "your sorrow and your pride."

Accompanied to the memorial service by American space heroes Neil Armstrong and John Glenn, Bush offered a solemn tribute.

"The loss was sudden and terrible, and for their families the grief is heavy. Our nation shares in your sorrow and in your pride," Bush told the thousands from the space community still in shock at the loss.

Quoting astronaut David Brown as telling his brother some weeks before the mission that the space programme would "go on" even if something went wrong, Bush said: "Captain Brown was correct. America's space programme will go on."

Moments later, the crowd stood for the tolling of seven bells for each fallen astronaut and four Nasa jets rocketed directly overhead in a "missing man" formation.

It was at Johnson Space Centre where mission controllers had monitored Columbia's last minutes of life, noticing an alarming increase in temperatures aboard the spaceplane then hearing commander Rick Husband's last communication: "Roger, buh," before his words were severed like the chopping of a phone line.

Scheduled to land 16 minutes later in Florida, the shuttle instead broke apart 80 kilometres up going at 20,000 kilometres per hour, sprinkling burning hulks of the spacecraft down to the Texas plains far below.

Recovery teams are still scouring the Texas countryside for debris that is hoped to hold clues to the cause of the disaster.

Columbia's nose cone was reported found on Monday and Nasa reversed itself on the damage to the orbiter at launch, saying it was starting to look like the previously discounted incident was an important piece of the puzzle over the cause of the breakup. (Reuters)

The crowd at the space centre, many of them wiping tears from their eyes, were gathered at a courtyard on a warm, sunny day for the funeral-like memorial service of hymns and speeches.

Near the speakers' platform was a large photograph of the smiling seven, five men, including Israel's first astronaut, and two women, all dressed in orange flights suits, preparing for the 16-day mission. Memorial flowers and balloons decorated the entrance to the Nasa complex.

Mentioning each by name, Kent Rominger, chief of the astronaut corps, fought back tears when he said: "I know you're listening. Please know you are in our hearts, and we will always smile when we think of you."

The crew included shuttle commander Rick Husband, pilot William McCool, payload commander Michael Anderson, payload specialist Ilan Ramon, an Israeli Air Force colonel, payload specialist Laurel Clark, payload specialist David Brown and payload specialist Kalpana Chawla, a U.S. citizen born in Karnal, India.

"Today our grief is overwhelming," said Nasa Administrator Sean O'Keefe, who vowed a relentless effort to "make sure this doesn't happen again."

"We owe this to you, the families and to the American people. With an uncompromising commitment to safety, we will keep this solemn pledge," he said.

Bush brought with him aboard Air Force One Armstrong, the first man to walk on the moon, and Glenn, the former senator and space pioneer who was the first American to orbit the earth.

Despite the loss of a second shuttle - Challenger blew apart on liftoff in 1986 - the White House said Bush was committed to continuing the shuttle program. The remaining three shuttles are grounded until the cause of the accident is known and corrected.

"The president understands that manned space flight is a risky mission," White House spokesman Ari Fleischer told reporters. "And it's a risk that the president thinks is in our national and international interest."

Nasa's painstaking investigation is now focusing on whether foam insulation that flew from an external fuel tank on the shuttle's liftoff on Jan. 16 damaged Columbia's system of ceramic tiles designed to protect its underbelly from the superhot temperatures reached on re-entry from space.

The debris hit the underside of the left wing and may have damaged tiles that protect Columbia from the searing heat of reentry, where the outside temperatures can reach 1,650 degress Celsius.

Nasa Shuttle program manager Ron Dittemore said they were particularly interested in finding "upstream" debris, particularly tiles that may have fallen off the shuttle earlier than previously thought as it glided across California, Arizona and New Mexico.

Nasa reversed itself on the damage to the orbiter at launch on Monday, saying it was starting to look like the previously discounted incident was an important piece of the puzzle over the cause of the breakup.