With somber ceremonies, the United States on Friday commemorated the loss of the space shuttle Columbia and its seven-member crew on the tenth anniversary of the disaster.
Columbia, Nasa's first space shuttle orbiter to be put into service, disintegrated during re-entry on February 1, 2003, as it was ending its 28th mission.
All seven astronauts on board died in the landmark incident that triggered the end of the shuttle mission.
"Ten years ago, seven brave astronauts gave their lives in the name of exploration when America's first flight-ready space shuttle, Columbia, failed to return safely to Earth," President Barack Obama said in a statement.
At a ceremony at the Space Mirror Memorial on the grounds of the Kennedy Space Center in Florida, those remembering the dead included Evelyn Husband Thompson, the widow of the shuttle commander Rick Husband, as well as former astronauts and representatives of the US space agency, Nasa.
Meanwhile, Nasa Administrator Charles Bolden and a delegation gathered at Arlington National Cemetery near Washington where three of Columbia's crew members are buried.
Columbia's demise was triggered when a loose piece of insulating foam from the external fuel tank that had peeled off during the shuttle's launch 16 days earlier struck one of Columbia's carbon composite wings.
After the incident, the administration of former president George W. Bush decided to put an end to the shuttle program, allowing the three remaining orbiters to fly only as long as it took to complete the International Space Station -- in 2011 -- and to honor Washington's commitments to its partners.
Aside from 45-year-old Husband and his co-pilot William McCool, 41, the crew consisted of: Kalpana Chawla (41), Michael Anderson (43), Laurel Clark (41), David Brown (46) and Ilan Ramon (48), Israel's first astronaut.
Six of the seven were married and together they had a total of 12 children.
Friday's annual Day of Remembrance also honors others killed in other space-related incidents.
Three American astronauts died after a fire swept through the Apollo 1 aircraft during a test run in January 1967, and the explosion of the space shuttle Challenger in January 1986 shortly after take-off killed all seven crew members aboard.
"As we undertake the next generation of discovery, today we pause to remember those who paid the ultimate sacrifice on the journey of exploration," Obama said.