Limitations in the CAIB Report

CAIB chair Hal Gehman said, “We’re very proud of our report. I’m on the speaking circuit, I don’t talk about space, I talk about risk assessment, risk management, and safety. I’ve been to lots of places, and our report is being used as a textbook.”

There are some issues brought up by the CAIB where I feel they were wrong. Even with all of these limitations the CAIB report is still an excellent analysis for what happened, and unlike many technical reports very readable.

The CAIB says NASA was under internal pressure to launch STS-113 (the mission between the bipod loss on STS-112 and STS-107) because of the length of time the three person Expedition 5 crew spent in space. Expedition 5 was launched in June 2002 and scheduled to spend four months in space and return home on STS-113 in October before the flowliner problems grounded the fleet. But the four months is just the planning schedule. It's always been stated it's a flexible number with anywhere between four to six months acceptable. Even six months is an arbitrary limit, the plan has always been if a crew has to spend more than six months because of operational limitations (e.g. shuttle delays) the flight surgeons will interview the astronauts and make a recommendation. Many Russian cosmonauts have made far longer missions without any long term health problems. The previous ISS crew, Expedition 4, spent 6.4 months in space, two months longer than planned. NASA tends to be more conservative than Russia about stretching the limits for longer crew duration in space. There's no reason to believe STS-113 was under pressure to launch just to return Expedition 5 home on schedule.

There could have been a concern if there were additional delays to STS-113 it might interfere with the Christmas holidays where traditionally the shuttle program stands down, but past history shows NASA will fly a shuttle mission over Christmas if necessary. STS-113 could have delayed up to mid December before it would impact STS-107. Hypothetically if technical problems did delay STS-113 for a couple of weeks then STS-107 would have also delayed a couple of weeks. It would take at least another month of delays to STS-113 before requiring another major change to STS-107’s schedule. If there was a greater delay to STS-113 and it only affected that particular shuttle then it’s possible the flight order could have been reversed again with STS-107 flying before STS-113. If there was a serious concern about the health of ISS astronauts because of the length of their stay they could have returned to Earth in their Soyuz spacecraft, but that would have been a fairly major decision. Certainly large STS-113 delays would affect the plans to complete the U.S. portions of ISS on schedule in February 2004, but they would not have directly affected STS-107.

The CAIB report says pressure to complete ISS on schedule resulted in additional pressure to launch STS-107. The many STS-107 delays show it actually functioned as a “relief valve” for ISS flights. In June 2002 the shuttle schedule was supposed to be STS-107 in July, STS-112 in August, and STS-113 in October. Because of the flowliner delays managers made the decision to push STS-107 behind the two ISS flights. That permitted the ISS missions to fly with only about a one month delay to each flight. NASA managers were always willing to give STS-107 less schedule priority than ISS flights. Once people started to live on ISS the shuttle's number one priority had to be supporting space station’s astronauts. Other missions, like STS-107, would by definition get lower schedule priority - as they should. There’s no reason to believe managers would have hesitated ordering another delay to STS-107 if necessary to keep the ISS flights on schedule.

It’s also extremely important to note that even with the pressure to keep the space station’s construction on schedule managers were perfectly willing to ground the fleet because of the flowliner cracks. The difference between the flowliner delays and bipod incident on STS-112 is falling foam was considered “acceptable” and not a safety issue since it had happened in the past while the flowliner was an unknown situation and recognized as potentially dangerous.

The CAIB says the decision to schedule Columbia for the STS-118 ISS assembly mission put additional pressure to launch STS-107 as quickly as possible because any delays to STS-107 would result in less time to turnaround Columbia for STS-118. STS-118 was planned for November 2003. It would be a relatively slow processing period with a less hectic pace than the other shuttles and preplanned storage periods when the other shuttles had higher priorities. Both Atlantis and Endeavour were scheduled to fly twice during the nine months between Columbia’s STS-107 and STS-118 missions.

The CAIB report says it’s a complicated operation to shuffle shuttles between the OPFs and the storage area in the VAB. But what’s not in the report is it was a common and well understood activity whenever NASA had to juggle its fleet. Because of the flowliner problems Columbia spent three separate periods in storage so STS-112 and STS-113 could be processed for their missions.

The shuttle processing teams can be very flexible with how OPFs are scheduled. In one case the decision to move Endeavour from its OPF to the storage area to free up the OPF was made after the go-ahead for Columbia’s deorbit burn on STS-83. If Columbia remained in orbit for another day or got diverted to the alternate landing site in California then Endeavour could continue to use the OPF. But once the go for the deorbit burn was given technicians moved Endeavour to the VAB storage area so the OPF could be cleared for Columbia’s use after it landed. With the loss of Columbia NASA now has three shuttles and three OPFs, so each shuttle can have its own dedicated hangar and there will be far less need to juggle shuttles anymore.

The connection between assigning Columbia to the STS-118 ISS mission resulting in additional pressure to launch STS-107 is a very shaky one at best.

It's important to note even without STS-107, even without any limitations on how long an ISS crew can stay in space, and even without an arbitrary deadline to finish ISS by a certain date there was pressure to keep the shuttle fleet flying to support ISS because there are people onboard. The live-aboard crews need oxygen, water, and food and that means a steady supply line, plus a full “pantry” in case a delivery flight is missed or delayed for whatever reason. That will always be a concern whenever there are long term astronauts in space and especially when there’s a limited number of ways to send supplies. ISS is similar to Antarctic research. Some supplies can be stored at the South Pole but there has to be an uninterrupted flow of supplies for the researchers. During the harsh Antarctic winter all of the planned supplies are sent in advance and if necessary a plane can fly over the pole and drop a parachute load of emergency supplies. But occasionally it's necessary to perform a medical evacuation or get critical supplies through the harsh weather and safety margins may have to be reduced to accomplish the mission.

The CAIB notes NASA performed an inspection of the shuttle on STS-27 when the tiles were damaged but did not on STS-107. But the report de-emphasizes on STS-27 the shuttle’s robot arm was onboard and it was a far less busy mission. That made it an almost trivial task to inspect the shuttle’s belly. In contrast on STS-107 a close-up inspection meant a spacewalk which would have been extremely challenging because of its location outside of Columbia’s cargo bay.

The report says none of the MMT members have classified clearances or knowledge about the Department of Defense’s capabilities. But any engineer could easily calculate the maximum theoretical resolution of images from a spy satellite or ground-based observatory.

The CAIB report notes the what-if e-mail exchanges between landing gear experts at NASA’s Langley Research Center in Virginia and shuttle engineers at JSC did not include MMT members. However those exchanges did include Jeff Kling, the Mission Control engineer responsible for Columbia’s landing gear, and entry flight director LeRoy Cain. They were the key people responsible for the second-to-second decisions during Columbia’s reentry and had more power than the MMT who do not have that responsibility or authority. According to NASA’s flight rules Kling could recommend to Cain for the crew to abandon Columbia or make a belly landing if he felt the problem with the landing gear was bad enough – but a MMT member could not. Kling recited the rules, “[The flight director] is in charge of real-time operations, especially during dynamic flight, and if we thought we needed to bailout that recommendation would come from me. LeRoy would assess it as reasonable or not, and he would make the [judgement] call and capcom would tell the crew to bailout.”

The report is correct when it notes the Debris Assessment Team should have asked Dave Brown to downlink the rest of the video he shot of the ET. Brown certainly shot far more footage than what was broadcast, but for the most part it would have been extremely similar. Reading the CAIB report gives the impression the additional footage could have shown the ET’s other side with the bipod fitting and the missing foam. Even if that was true the video resolution would have been low and extremely doubtful whether or not any lost bipod foam could have been detected.

The CAIB notes it was the first time Boeing engineers in Houston used the Crater program to predict the amount of damage to the shuttle’s tiles and they did it without any support from the experienced Boeing team in California. Only in passing does the CAIB note the engineers’ training was “excellent” and they were completely qualified. Originally the engineers who supported the space shuttle were located in Downey California, near Los Angeles. Because of various mergers Boeing decided to close the Downey plant and move its workforce to nearby Huntington Beach. Boeing later decided to move its shuttle support functions from California, where the shuttles were manufactured, to Houston. Besides being closer to Mission Control it would save money due to the difference in expenses between Southern California and Houston. There were concerns many of Boeing’s experienced engineers in California would not want to move to Houston, even if they were offered moving expenses and the same salaries and benefits. Boeing responded with a program where important shuttle engineers who did not want to move to Houston were offered jobs with other Boeing divisions in the Southern California area. That way their expertise would remain “in house” and they could be called upon for advice if needed. If the debris analysis team in Houston wanted to they could have called upon the experienced engineers in California.

The CAIB report almost portrays the MMT as being unconcerned about STS-107’s foam damage, especially the attitude “there’s nothing we can do about it anyway”. What’s important is the context for that attitude. Mission Control has always operated under the axiom that once a shuttle is launched the options are very limited. The reason there was no serious plan for a shuttle rescue mission is the extremely small – almost non-existent – situations where one could be used with any chances for success, even assuming another shuttle’s already ready to launch on a rescue mission. The shuttle can only carry a limited amount of supplies – and once they’re used up it has to return to Earth – there’s no other choice. It’s similar to skyscraper owners not providing escape parachutes for their occupants, just in case the building is on fire or attacked by terrorists. There are just too few situations where such an extraordinary effort would be useful and just as low chance they could be used successfully. NASA’s intent is always to make sure the safety and quality controls are in place to prevent situations like STS-107 from happening. The attitude “there’s nothing we can do about it anyway” was not callous or unfeeling – it’s a simple fact of life. In an effort to prove that that attitude was incorrect the CAIB instructed NASA to come up with a rescue plan which could have worked. The rescue scenario would only work if there was hard evidence Columbia was doomed extremely early in the mission - plus the willingness to put another shuttle and crew at risk too. While the attitude “there’s nothing we can do about it” may be wrong, at most the actual attitude for STS-107 should have been “there’s so little we can do about it and only under such extremely limited scenarios and with a lot of hindsight we shouldn’t dwell on it.”

The CAIB says that once ISS’s assembly started the order for the shuttle flights became inflexible with space station pieces needing to be launched in sequence. They noted that a problem holding up one shuttle would cause a ripple effect that would delay later flights. That’s only partially true. In several cases managers considered flying flights out of order. STS-104 carried ISS’s airlock while STS-105 was a logistics flight and crew exchange mission. STS-104 had to be put on hold when there was an issue with ISS’s robotic arm and it temporarily delayed flights until new software was developed for the space station arm. But STS-105 only needed the space shuttle’s arm and managers considered swapping the order of STS-104 and STS-105 primarily to keep the crew exchange flight as close to the originally planned date as possible. The primary change would be additional training for the new crew to operate the ISS arm to install the airlock since they would be onboard when it arrived. As it turned out the delay was fairly short and the flight order didn’t need to be changed. Another case was when the flowliners grounded the fleet. STS-112 had a piece of ISS’s truss. STS-113 had a piece of the truss for the opposite side and was also a crew exchange flight. If the flowliners problem took longer to fix than anticipated then STS-113 could have flown first and performed the crew exchange, followed by STS-112. There was no strict requirement to fly those truss segments in order.

The ISS assembly missions after STS-107 are flights to add additional segments to the truss, first the starboard side and then the port. On each side the pieces have to be assembled in order. But hypothetically if a shuttle was grounded with a piece for the starboard side NASA could fly whatever piece was next on the port side instead. Certainly once ISS’s assembly was started it reduced the flexibility in swapping the order of the shuttle missions, but there is still some flexibility.

Home

copyright 2005 Philip Chien All Rights Reserved