Loose foam at launch might be related to shuttle crash, officials say.(Chicago Tribune)

Byline: Jeremy Manier

NASA officials will be investigating whether loose foam that struck Columbia during takeoff 16 days before it exploded Saturday contributed to its disintegration under the extreme physical stress of re-entering the Earth's atmosphere _ one of the most dangerous parts of any shuttle mission.

Cameras detected the foam insulation breaking free from an external fuel tank and striking Columbia's left wing, prompting days of review while the shuttle was in space over whether the orbiter's safety had been compromised, officials said Saturday.

The sparse information NASA had Saturday seemed to point to failures on the craft's left side. Sensors on the shuttle's left wing and in the left wheel gear detected a sudden temperature increase or stopped working minutes before the vehicle exploded 207,000 feet over Texas as it flew at 12,500 mph.

Although it's possible the foam knocked off heat-resistant tiles the shuttle needs for re-entry, officials said, it's too soon to draw conclusions.

"Is that the smoking gun? We do not know," shuttle program manager Ron Dittemore said during a news conference Saturday. "There are a lot of things in this business that look like a smoking gun but turn out to be not even close."

Experts said many other malfunctions could have destroyed the shuttle during re-entry, when a cocoon of hot plasma envelops the spacecraft.