Safety of the astronauts

The foam debris problem continues to hound the space shuttle fleet. Four years and $235 million later, it appears the problem has not been solved.

Another piece of foam dropped from the fuel tank bracket during launch of the shuttle Endeavour last week, bounced off a strut and slammed at 200 mph into its critical heat shield. Like what happened in the ill-fated shuttle Columbia, the foam gouged a portion of the thermal tiles. The gash was not quite as big as Columbia’s 6-inch by 10-inch hole; it was only a 3 ½- by 2-inch gouge.

NASA officials have announced that the damage to the heat shield does not pose a threat to the safety of the astronauts. But NASA will decide Wednesday whether the astronauts will go on a spacewalk to repair the damage. They carry a repair kit with them: this was one of the safety recommendations of the review board that investigated the Columbia shuttle disaster.

So the heat shield may be repaired, the shuttle will be able to endure the heat of atmospheric re-entry, and get back to Earth without further damage. That will be one emergency safely resolved. But the shuttle’s problems remain.

There is the question of whether safety concerns are being downplayed because of a tight flight schedule. The shuttle program has already been delayed four years, and at least 12 but desirably 14 more flights are needed in order to complete the International Space Station by the time the shuttle fleet retires in 2010.

Take the foam debris. NASA was aware that foam could still pop free from their attachments to aluminum brackets that secure a pipe to the fuel tank. When the shuttle Atlantis was launched last September, foam popped off the brackets; before the shuttle Discovery’s launch last December, foam actually fell off a bracket.

Going into the countdown last week, inspectors had spotted a crack in foam on a lower bracket. But mission managers decided the foam was positioned too low on the tank to pose a threat to the orbiter (note: that crack was not responsible for the foam debris that broke loose).

It has been said that succumbing to schedule pressures, despite significant issues on safety, contributed to the disasters of Challenger in 1986 and Columbia in 2003.

NASA could defer three more flights scheduled between now and April. These flights will utilize the aluminum brackets which have been associated with the perennial foam debris problems. In April, a new tank redesigned to use titanium brackets will be deployed. The new brackets will have lesser likelihood of shedding foam.

Should the three flights be delayed, for safety considerations? This will add even more to the pressures of schedules. This is a tough question that NASA officials must face in the coming weeks.