Full Article from MSNBC THE CRASH was the first fatal accident in America’s space program since the 1986 explosion of the Challenger, which also claimed seven lives. That disaster grounded the shuttle fleet for almost three years and raised deep questions about the risks of space flight. “The Columbia’s lost,” President Bush told the nation in a brief, emotional address he delivered after rushing back to Washington from Camp David, Md. “There are no survivors.” Although “our entire nation grieves,” said the president, who ordered that flags be flown at half-staff through Wednesday, the astronauts’ deaths will not spell an end to space exploration. “The cause in which they died will continue,” he said. “Our journey into space will go on.” FIERY DESCENT NASA Administrator Sean O’Keefe said Columbia broke up in flames as it re-entered the Earth’s atmosphere, spreading debris over hundreds of miles of Texas, just 16 minutes before the 100-ton shuttle was to have landed at Kennedy Space Center in Florida. It is possible the seven astronauts on board were alive through much of the shuttle’s descent and breakup and is unlikely they were killed instantly, a NASA official told NBC News. Columbia’s crew members completed more than 80 scientific research experiments during their time in orbit. O’Keefe described them as having performed their mission brilliantly and said in a broken voice, “The loss of this valued crew is something we will never be able to get over.” As investigations began, an official of the Department of Homeland Security told NBC News on condition of anonymity there was no indication that terrorism was involved. Security was extraordinarily tight on this mission because of the involvement of Israeli Air Force Col. Ilan Ramon, Israel’s first astronaut. NASA officials feared that Ramon’s presence could have made the shuttle more of a terrorist target, but security officials reported no threats. SENSORS WENT OUT NASA said the first signs of a problem came only minutes before contact was lost, when sensors stopped working on the shuttle’s left wing. Shuttle program manager Ron Dittemore told reporters that those failures were followed within minutes by several other problems, including the loss of sensors for tire pressure and temperature. The final radio transmission between Mission Control and the shuttle, at 9 a.m. ET, gave little indication of trouble. WashPost: Experts warned of safety worries Mission Control radioed: “Columbia, Houston, we see your tire pressure messages, and we did not copy your last.” Columbia’s commander, Rick Husband, calmly responded: “Roger, uh, buh ...” For several seconds, the transmission went silent; then, there was static. Most of the wreckage apparently landed in an area of many thousands of square miles between Waco, Texas, and the Louisiana border. One man reported finding what appeared to be a charred torso, thigh bone and skull on a rural road near what appeared to be other debris. NASA warned the public not to touch the debris, saying it could be contaminated with toxic fuel. It urged anyone finding debris to notify local authorities. Police and National Guard troops sealed off all suspected pieces of debris as soon as they could arrive at the scene. Advertisement FOCUS ON TILES No one expected quick answers. Experts said it would probably take months to work through the complex investigation. “We have to look at it in two different ways: Was there an in-flight breakup that resulted in an explosion of the aircraft, or was there an explosion that resulted in the in-flight breakup?” Gregg Furth, a former investigator for the National Transportation Safety Board, told NBC News. After the shuttle launched on Jan. 16, mission managers said a piece of insulating foam had broken off from the external fuel tank and might have hit the left wing. At the time, NASA said the incident did not raise safety concerns. The loss of even a few of its heat-shielding tiles could put the shuttle at greater risk as it hurtled through the atmosphere, however, Dittemore said Saturday that “we can’t discount that there might be a connection.” Former astronaut Ron Hauck told NBC News: “You worry about that hurricane-force wind upon re-entry ripping more and more tiles off. And if that’s the case, the heat could melt through the aluminum skin of the orbiter.” Dittemore cautioned, however, that “we can’t rush to judgment on it.”