A somber President George W Bush today delivered the news that "the Columbia is lost" and led grief-stricken Americans in mourning the death of the seven-member shuttle crew in what he called a day of "great sadness."
"The Columbia is lost. There are no survivors," Mr Bush said in an address to the nation from the White House Cabinet Room after the worst space disaster in 17 years.
"This day has brought terrible news and great sadness to our country," Mr Bush said after returning to the White House from the Camp David presidential retreat.
The President ordered flags at the White House and elsewhere flown at half-mast and consoled the families of the astronauts who perished.
He also called Israeli Prime Minister Mr Ariel Sharon to express sorrow at the loss of Israel's first astronaut, Col Ilan Ramon, who was flying on the shuttle when it broke up over Texas on its return from a 16-day science mission.
"These men and women assumed great risk in the service to all humanity in an age when space flight has come to seem almost routine," Mr Bush said. "Because of their courage and daring and idealism we will miss them all the more."
Administration officials said there was no indication terrorism was involved - at 200,000 feet (63,000 meters) up, it was out of surface-to-air missile range - and no threat had been received targeting the spacecraft.
Mr Bush has vowed that the US space programme would continue despite the second loss of a space shuttle after Challenger blew up on takeoff in 1986. Columbia was NASA's oldest shuttle and first flew in 1981.