Transcripts of meetings by senior NASA managers during the shuttle Columbia's ill-fated flight show mission management team chairman Linda Ham and other top officials, despite a dearth of technical data, simply did not believe falling insulation from the ship's external fuel tank could cause a catastrophic breach in the ship's left wing.
The transcripts include extensive discussions of relatively minor temperature control problems with Columbia's Spacehab research module and debate about the shuttle's slightly over-limit landing weight. But there is surprisingly little discussion about the foam strike investigators now believed doomed the ship 81 seconds after blastoff Jan. 16.
Instead, the mission management team (MMT) unanimously accepted, with only a smattering of questions from Ham, the results of a hurried analysis that concluded the worst threat Columbia faced was possibly severe, but localized, tile damage that might require repairs between flights.
Ham has declined all interview requests since the shuttle tragedy and has not participated in any news briefings to this point. With the benefit of 20-20 hindsight, she has been criticized by some observers for not recognizing the severity of the foam strike and its potential for causing catastrophic damage. As chairman of the MMT, she also has been blamed for quashing efforts to obtain spy satellite photography of the shuttle to better characterize any potential damage.
But the widely reported, unsuccessful efforts to obtain spy satellite imagery were not discussed at the MMT meetings, the transcripts show, and in any case, sources say, those efforts primarily were derailed by lower level managers before reaching the MMT chairman.
Ham remains in the shuttle program office at the Johnson Space Center, but earlier this summer she was removed from her post as program integration manager and replaced by flight director John Shannon, who will assume at least some of her duties. Wayne Hale, a former flight director who now serves as deputy program manager under William Parsons, is expected to assume Ham's role in future MMT meetings.
As for Ham's role chairing the MMT meetings during Columbia's flight, the transcripts show no particularly unusual comments on her part or any obviously questionable decisions. But surprisingly, the foam strike was never a top-of-the-agenda item and it was discussed only sparingly, in summary format, and with no debate even though the strike was the most significant such impact ever observed.
When it was discussed, the team focused almost totally on possible damage to the heat shield tiles on the underside of Columbia's left wing and all but dismissed the possibility the foam strike could have damaged the reinforced carbon carbon — RCC — panels making up the wing leading edge. This was a particularly striking turn of events considering there was little or no test data on how the carbon composite leading edge panels might respond to a strike by a large piece of foam and there was uncertainty about exactly where the foam had hit the wing.
During the third MMT meeting of Columbia's mission, held on Jan. 24, Don McCormack, representing NASA's mission evaluation room support team, told Ham engineers had started an assessment of potential tile damage using a program called "Crater."
While the analysis was not yet complete, McCormack said, "obviously there's potential for significant tile damage here, but they do not indicate, the thermal analysis does not indicate, that there is a potential for a burn-through. There could be localized heating damage. Obviously, there is a lot of uncertainty in all this in terms of the size of the debris and where it hit and angle of incidence and, uh, it's difficult..."
"No burn-through means no catastrophic damage and localized heating damage would mean a tile replacement?" Ham asked.
In the process of discussing potential tile damage, Ham and her colleagues never revisited the RCC issue even though there was little or no data presented about how the carbon composite panels would respond to a significant impact. And the impact seen during Columbia's launching was the most significant on record.
After complaints that MMT participants listening in by phone could not hear, Ham repeated that Schomburg, who had no expertise in RCC systems, "does not believe that there is any burn-throughs, so no safety of flight kind of issue. It's more of a turnaround issue similar to what we have had on other flights. That's it? All right, any questions on that?"
There were no questions. And with that, any lingering concern about the health of the RCC panels was dismissed.
The foam in question broke away from the left-side "bipod ramp" area of the external tank where two large struts attach the nose of the shuttle to the top of the tank. To keep ice from forming on the struts and falling onto the shuttle, foam insulation is sprayed on the tank and then sculpted by hand to form two aerodynamic ramps, or slopes, at the base of each strut making up the bipod.
Eighty-one seconds after Columbia blasted off from the Kennedy Space Center, a 1.67-pound chunk of foam from the left bipod ramp area broke free and slammed into the ship's wing at more than 500 mph. Engineers now believe it hit the leading edge on the lower side of RCC panel No. 8, punching a hole in the panel or causing enough damage to result in breach of some sort.
Recent tests at the Southwest Research Institute in San Antonio, Texas, clearly demonstrated such a breach was possible.
While the details are not known with certainty, engineers believe Columbia re-entered Earth's atmosphere Feb. 1 with a hole of some sort in the left wing leading edge. Sixteen minutes after falling into the discernible atmosphere, Columbia's flight computers lost control of the orbiter and the shuttle broke apart. Commander Rick Husband and his six crewmates were killed.
CBS News Space Consultant William Harwood has covered America's space program full time for nearly 20 years, focusing on space shuttle operations, planetary exploration and astronomy. Based at the Kennedy Space Center in Florida, Harwood provides up-to-the-minute space reports for CBS News and regularly contributes to Spaceflight Now and The Washington Post.
By Bill Harwood