HOUSTON The first public hearing held by the Columbia Accident Investigation Board (CAIB) heard expert testimony Thursday on NASAs bureaucracy, roles between the space agency and contractors, and checks and balances to guarantee a space shuttle flies safely.

But as for the root cause of Columbias breakup and loss of its crew on Feb. 1, that puzzle remains unsolved.

Sitting on a stage here at a University of Houston/Clear Lake auditorium, with tables draped in black cloth, eight CAIB members listened intently to a set of four witnesses, each of whom were asked to vouch for the accuracy of the information they would provide.

Jefferson Howell, Jr., Director of NASAs Johnson Space Center (JSC) here, noted the civil servant and contractor workforce specific to his operation totals some 16,000 people on and off site.

NASAs shuttle chief, Ron Dittemore, said the Columbia accident has galvanized government and industry workers to ascertain why the space plane and crew were destroyed on reentry over Texas.

"The morale is generally pretty good considering the conditions were operating under," Dittemore explained. "Its been six weeks since we had an event that changed all our lives."

Dittemore explained that the best therapy for all those on the shuttle program was to solve what happened to Columbia. "Everybody wants to be engaged in this effort, without exception."

Shuttle teams are now tirelessly looking into the accident, Dittemore said, and are likely to identify weaknesses in the space shuttle system that are broader than the root cause of the Columbias destruction. There is no discussion regarding cutbacks to the workforce given the grounding of the shuttle fleet, he said.

"Well need every one of them in our workforce to get us through this period of time," Dittemore told the CAIB.

Dittemore echoed Howells view that NASA is facing erosion of its skill base. Furthermore, he has concerns regarding the balance of government and contractor workers. A "lean and mean" NASA, and still be safe, is not credible, he said.

In recent times, Dittemore added, the shuttle program has undergone a shuffling of contractor work, moving industrial support from California and replanting that help at JSC and the Kennedy Space Center in Florida. That move of people and hardware has been disruptive, but also beneficial in some areas to the program, he said.

Safety reviews and quality assurance "is our life blood," Dittemore said. A mix of checks and balances and "healthy tension" between engineers and shuttle operations is in place, he said.

"We have cultivated that culturewe want the people in our system to challenge the assumptions," Dittemore said. Anybody having "what if" viewpoints would find an open door policy in the shuttle program, he said.

Dittemore said that the shuttle safety track record "is there to defend ourselves."

Another witness, Keith Chong, a Boeing senior scientist from Huntington Beach, Calif., detailed work on foam insulation applied to large propellant tanks, both in the shuttle external tank as well as the companys Delta 4 booster.

Chong said that under the U.S. Air Forces Evolved Expendable Launch Vehicle program, the Delta 4 propellant tank carries foam insulation similar to the shuttles external tank.

For the Delta 4 program, Chong said, a special laser scanning system is utilized to show any problems in the foam bonding to the fuel tank. In ten seconds, a two-foot by two-foot area of foam can be certified okay for flight, he said.

Chong said due to environmental issues, the use of Freon was halted as a blowing agent in foam processing. Foam flaking called the "popcorn effect" -- was one by-product of that decision, he said.

A recommendation by Chong was for NASA to look into the laser scanning technology for adoption in certifying that shuttle external tanks are ready for use.

The final witness, former NASA Ames Research Center Director Henry McDonald, focused his remarks on a Space Shuttle Independent Assessment (SIAT) report he led before leaving his NASA post.

That report uncovered what McDonald termed "near misses and diving catches" within the shuttle program.

"The shuttle program is one of the most complex engineering activities undertaken anywhere in the world at the present time," said McDonald, who is now a professor of computational engineering at the University of Tennessee at Chattanooga.

McDonald said there is no doubt that NASA is safety conscious. "The question has been how to translate that into a safe and effective program. That is very, very difficult given the complexity of the issue."

McDonald said the SIAT report flagged a number of issues, with some of those concerns not embraced or adopted by NASA. "I was personally disappointed that some of the recommendations were not carried out," he said.

In particular, McDonald said, the tracking of waivers and problem areas encountered within the shuttle program requires a new database system one more in tune with information technology handling capabilities of the day.

Congressional budget cuts in the past for shuttle upgrades aced out monies for such new data handling concepts, McDonald said. That kind of capability could help spot trends and uncover problems that might go unnoticed in readying each shuttle for a mission, he said.

CAIB chairman Gehman asked if McDonald would agree with the observation that "hiring more inspectors is not the issue." McDonald did.

Overall, its McDonalds view that NASA may well have become lulled into a false sense of security - with Columbia as a horrific wake-up call. "Its a question of risk assumption and perceptionand that is a complicated animal," he said.

Gehman said the first public forum served as a foundation for moving forward. "Im not going to tell you what we learnedyou saw us scribbling like mad," he told reporters after the public meeting.

Gehman said that future public hearings are intended to work chronologically through the shuttle system and the last flight of Columbia.

Witnesses asked to speak before the CAIB in the future will also come from both NASA and outside the agency, he said.

"We thought the witnesses were all very forthcoming. They all answered our questions fully. Nobody was defensive. So we are quite happy with the witnesses," Gehman concluded.