The world's other major space power, Russia, sent its condolences to Washington, but yesterday went ahead with the launch of a cargo rocket carrying food and fuel to the International Space Station (ISS).
The seven members of Columbia's crew had "given their lives to conquering the dangers of space in the name of peace, science and progress of civilisation", Russian President Vladimir Putin said of Saturday's tragedy.
Russia's Baikonur cosmodrome in the Kazakh steppe was in grief as the supply ship took off for the space station, which is manned by a joint US-Russian crew. "Nobody had expected a tragedy like this, and we are in mourning and grief," said Oleg Urusov, editor-in-chief of Baikonur's main space magazine Kosmodrom.
"Baikonur residents, as people close to the space industry and space exploration, take the Columbia catastrophe as they would the loss of their own loved ones," he added.
A wave of sorrow engulfed Israelis as what was expected to be the triumphal return of Israel's first astronaut, former combat pilot Colonel Ilan Ramon, became another dashed dream.
Col Ramon's five-year-old daughter Noa, who was in Houston hoping to welcome her father home, was reported to have asked her mother: "How can you die in space? People are supposed to die only on earth."
The launch of Col Ramon's space flight had lifted the spirits of Israelis. But as debris came crashing down on a Texas town called Palestine an irony lost on no one national morale plunged anew.
Palestinian President Yasser Arafat and the Palestinian Authority Israel wants disbanded expressed condolences to the families of all seven astronauts.
Pope John Paul, in his weekly address in St Peter's Square, called on people to pray for the crew and said his prayers were with their families.
"The painful news of the tragic explosion of the US space shuttle Columbia has triggered sharp emotions in everyone," the 82-year-old Pontiff told hundreds of faithful.
"I invite everyone to pray for the victims of the accident. At this extremely testing time, I am spiritually close to the relatives. I assure them that I will remember them in my prayers."
Japan, which had been due to send up its fifth astronaut on a US shuttle next month, said the disaster would deal a blow to its space programme.
Officials said astronaut Soichi Noguchi's mission would be postponed.
"The accident not only poses a serious situation for the US manned space programme but also for the ISS project, which our nation is also taking part in," Science Minister Atsuko Toyama said in a statement.
The station is being built by Russia and the United States with the help of space agencies from Europe, Canada and Japan.
China, which hopes to become the world's third nation to launch a manned spacecraft, possibly later this year, also sent condolences to the United States and Israel.
Chinese President Jiang Zemin told President George W Bush China deeply regretted the loss of Colombia's seven crew but he believed the exploration of space would continue.
Cuba, long-time ideological foe of the United States, also sent words of sympathy.
A Foreign Ministry statement said the Cuban flag would be flown at half-mast at the United Nations in New York out of respect for the American people.
The leaders of Germany and France, at odds with the United States over Washington's hardline attitude on the Iraq crisis, sent condolences to both the United States and Israel.
British Prime Minister Tony Blair, just returned from Washington and a council of war with Bush over Iraq, wrote to both the US leader and Israeli Premier Ariel Sharon expressing sorrow at the disaster.
In Baghdad, Iraqis on the street facing a possible US-led assault on their country said the tragedy was God's retribution on Americans.
"We are happy that it broke up," government employee Abdul Jabbar al-Quraishi said. "God wants to show that his might is greater than the Americans. They have encroached on our country. God is avenging us," he said.