A normal shuttle reentry (click on “Shuttle Breakup,” then select “How Shuttle Lands") into Earth’s atmosphere (called the “entry interface”) begins at 400,000 feet altitude. Five minutes before the entry interface, the shuttle is approximately 4,400 nautical miles (5,063 statute miles) from the landing site, traveling at speeds that can reach Mach 25.1 (as in this flawless re-entry and landing by Endeavour).
Columbia began preparations for reentry at about 8:16 a.m. EST. (Click on “The Final Hour” under "Shuttle Breakup.") She broke through Earth’s atmosphere at an angle, somewhere between 28-38 degrees, with NASA tracking all data. At 8:53 a.m. EST, temperature sensors showed the shuttle’s left wing was getting hotter.
While in her reentry mode, traveling at about Mach 18.3, Columbia began to fall apart. Immediately after the tragedy, NASA managers considered several possible causes for the failure. A seam at the wheel well door could have been impacted by the breakaway debris, the loss of thermal tiles could have caused a series of catastrophic failures or a combination of other problems (click on "Shuttle Breakup," then click on "Turbulence") could have been responsible.
Not until months later, during a thorough investigation, did officials realize that the leading edge of the orbiter's left wing was struck by a briefcase-sized piece of insulation (as depicted in these videos) weighing less than two pounds. The damage was not to the heat tiles but to a breach in one of the gray panels coated with an even stronger protective material: reinforced-carbon-carbon.
Because of that significant gash in her wing, Columbia became a fireball around 9 a.m. EST, sixteen minutes before her scheduled landing. With very short notice of serious problems, the crew likely realized - in the shuttle’s final moments - that they were about to die.
NASA officials acknowledge that Columbia began to lose parts while flying over California, but while over Texas, the shuttle disintegrated. People on the ground heard what appeared to be a series of sonic booms. Others with video recorders in hand, trying to capture the shuttle as it returned to home base, unexpectedly recorded the mission’s demise.
Because the shuttle was flying so fast, its debris field covers hundreds of miles. As bits and pieces of the orbiter rained on the earth, Doppler radar recorded the event as though it were part of a weather pattern. Damaged heat tiles - some so charred that their black ceramic coating is completely gone, leaving just the white silica base material - were found within Columbia's debris field. Recovered shuttle pieces, laid out in a hanger at the Kennedy Space Center, also helped investigators determine why the shuttle disintegrated:
The Columbia is lost; there are no survivors.
On Tuesday, February 4th, families of the crew members (twelve children were left behind) attended a memorial service for their loved ones. (Scroll to the end to view the video.) Many heartfelt words were spoken and thousands of NASA colleagues shared their grief. But it is with the words of the family members - those who lost the most - that we close this story:
On January 16th, we saw our loved ones launch into a brilliant, cloud-free sky. Their hearts were full of enthusiasm, pride in country, faith in their God, and a willingness to accept risk in the pursuit of knowledge -- knowledge that might improve the quality of life for all mankind. Columbia's 16–day mission of scientific discovery was a great success, cut short by mere minutes -- yet it will live on forever in our memories. We want to thank the NASA family and people from around the world for their incredible outpouring of love and support. Although we grieve deeply, as do the families of Apollo 1 and Challenger before us, the bold exploration of space must go on. Once the root cause of this tragedy is found and corrected, the legacy of Columbia must carry on -- for the benefit of our children and yours.