by Jay Chladek
Video footage shot by enthusiasts along Columbia’s reentry path showed that the orbiter was starting to shed debris as it flew over California. In Dallas, Texas, news cameras, which were pointed to the sky to capture the reentry, filmed Columbia’s final breakup, as did a U.S. Army Apache helicopter on training maneuvers near Fort Hood, Texas. A still photograph of the breakup taken by Dr. Scott Lieberman, a cardiologist and amateur photographer from Tyler, Texas, became one of the most published photos of the event in newspapers and magazines around the world.
Groups of volunteers and members of the National Guard were mobilized into debris search teams all over central Texas, as well as New Mexico and Louisiana. Hemphill, Texas, became a major staging area for the recovery since a couple of local residents had discovered what were believed (and later confirmed) to be human remains.
The recovery activities became quite a strain on the town’s resources as the area’s population swelled almost overnight with federal agencies and news media, but people got on with their jobs in a professional manner. Ultimately, remains of all seven astronauts and portions of Columbia’s nose and crew cabin were found within Sabine County’s borders. Local funeral home directors loaned their time and services to help with recovery and transportation of the astronauts’ remains. It was all done privately and with the utmost respect.
In that part of Texas, the volunteers for the search teams had a very difficult task in searching for debris, as they had to walk through some of the most densely packed woods in the country, standing shoulder to shoulder with one another so that no piece of debris, no matter how small, would be missed. When a piece was found, a handheld GPS device would mark the location, and photographs were taken before the piece was removed for analysis.
The work to recover the remains of Columbia was painstaking and took several weeks. When the spring rains came, it got cold, wet, and very muddy. But day after day, the volunteers went out and searched. In the end, more than seven hundred thousand acres were searched over a four-state area. It also had a human cost, though, as Francis “Buzz” Meir, a contract helicopter pilot with the Forest Service, and Charles Krenek, a manager of one of the search teams, were killed when their Bell 407 helicopter went down on 27 March 2003 during an aerial search for debris in a wooded area. Three other search team members on board survived the crash with serious injuries. In Texas the two men are memorialized alongside the seven astronauts.
Once in a while, new pieces of debris are still being discovered. About five years after the event, a resident of Hemphill, while making preparations to sell his home, got ready to patch a leaking roof. He noticed that a hole had been drilled through the roof and into the side of some storage boxes in his attic. When he opened one of the affected boxes, it contained a screw from Columbia. As before, NASA was contacted, and they sent representatives to recover the debris. A sphere from Columbia’s fuel system was also recently recovered when a lake was drained.
The residents of Hemphill to this day are proud of the work they did. To their credit, unlike some other places where debris was found, no residents of Hemphill or Sabine County made any attempt to keep or sell debris from Columbia. Today, the Patricia Huffman Smith NASA “Remembering Columbia” Museum (named for the late wife of the person who donated the land to build the museum) in Hemphill stands as a memorial that the general public can visit. Thanks to exhibits from NASA and items donated by the STS-107 crew’s families, the museum helps to tell the story of the space shuttle Columbia, STS-107, the recovery, and how things changed in that region of Texas on 1 February 2003.
Debris from the shuttle was collected in a hangar at KSC. As with an aircraft crash, the recovered pieces were laid out on a grid on the floor and placed in their proper locations on the vehicle. Some debris was burned beyond almost all recognition, while other pieces were almost completely intact with no visible signs of damage. One piece of equipment recovered in good shape was a data recorder fitted to Columbia for its test missions. Because the recorder was buried deep inside the shuttle, engineers did not remove it after the testing program had concluded. The recorder and its data tapes helped provide clues as to the sequence of Columbia’s breakup after all contact was lost with mission control. A videotape from a camcorder used by mission specialist Laurel Clark was also recovered in good shape. Clark had been recording Columbia’s reentry from the flight deck; while the portion of the tape that might have recorded the breakup had been too badly damaged, the rest of the tape revealed that up to ten minutes before the shuttle disintegrated, the crew was in good spirits and there were no signs of impending disaster.
Footage captured during launch revealed that the orbiter was struck by a large chunk of foam that came off an aerodynamic ramp on the shuttle’s ET. The foam was used to insulate the cryogenic fuel in the tank and keep heavy ice from forming on it. While the foam is flexible, contraction of the ET during fueling can still produce cracks. Pieces can come loose on ascent either from the cracks or from trapped air bubbles, causing foam sections to break off as outside air pressure decreases.
Prior to Columbia’s reentry, a few NASA engineers had expressed concerns in private emails that the foam might have damaged Columbia’s tiles on the left wing. But mission managers dismissed these concerns as shuttles had returned from orbit with tile damage before with no problems. Some engineers asked to have the DoD use its reconnaissance satellites to take images of Columbia’s wing, but management also rejected those plans. Managerial members of the shuttle program felt that if there were damage, it would just cause problems during turnaround of a shuttle for its next flight and would not be a safety risk on this one. They were very wrong in making that decision.
Enhancement of the launch footage revealed that the chunk of foam that hit the wing was about twenty-one to twenty-seven inches long by over twelve to eighteen inches wide and struck at a velocity from four hundred to nearly six hundred miles per hour due to the shuttle still accelerating from the thrust of its SRBs. While managers felt that tile damage wouldn’t be a concern, no attention was paid to the reinforced carbon-carbon (RCC) wing panels, which were designed to handle the highest heat loads of reentry. The RCC panels are very stiff. Although many consider them able to withstand a lot of abuse, the panels are also very thin compared to the tiles, and the areas behind them are hollow.
To test the theory that ET foam could damage RCC, engineers with NASA and other agencies took some RCC wing panels to the Southwest Research Institute in San Antonio, Texas, and fired foam blocks at them using angles and speeds suggested by the data analysis. During a full-scale test using launch video data, the foam block blew nearly a ten-inch hole in the middle of an RCC panel, and an audible “Holy shit!” could be heard on video footage of the test. People were shocked by what they saw. Regardless of what some had believed before, everyone now knew that a foam strike was what had doomed Columbia.
During reentry, heat plasma is normally kept away from the shuttle’s surface by its entry attitude and shape. A shuttle enters the atmosphere with its nose pitched up at forty degrees so that the bottom bears the brunt of the reentry. This creates a bow wake until the shuttle slows down enough that its nose can be lowered safely for a glide to landing. The shuttle’s heat-resistant tiles, blankets, and RCC panels keep the rest of the structure from overheating due to the air friction, but the tiles and RCC can’t resist the direct heat of plasma. The loss of a single tile is not enough to cause the plasma wave to be disturbed, but a large hole, especially in a critical area such as the leading edge of a wing, can cause the plasma to approach closer to the surface of the shuttle’s exterior and perhaps touch it. Due to the hole in the RCC panel, hot plasma entered Columbia’s wing.
Over the next several minutes, the plasma plume torched through wires, causing sensor dropouts, and melted the wing’s internal structure. The plume also opened up the hole in the wing wider. The wing’s shape itself gradually began to distort, shedding tiles along the way and exposing more of the orbiter�
��s aluminum structure to reentry heating. Columbia’s computers maintained control of the wing’s elevons and, near the end, activated thrusters to try to compensate for the increasing drag on that side. But eventually, Columbia’s hydraulic lines in the left wing were breached, rendering the elevons useless.
Columbia started to lose control at 07:59:37 CST when it lost hydraulic pressure, and nine seconds later it pitched up into a flat spin to the right. Seeing the indication on his monitor, pilot McCool flipped switches on a cockpit panel in an attempt to restart the shuttle’s auxiliary power units to try to get hydraulic pressure back, but it was too late. At 08:00:02 portions of the left wing and OMS pod broke away. The fuselage of the orbiter stayed together until aero forces ripped it apart, with the front fuselage and crew cabin separating from the rest of the orbiter about sixteen seconds later.
Later, tests revealed that the crew cabin started to depressurize when it separated from the fuselage. The crew would have had less than ten seconds of consciousness before passing out from lack of oxygen. Analysis of the retrieved suit remains revealed that none of the crewmembers had closed their helmet visors or activated their emergency oxygen packs. Even if they had done so in a now-darkened cabin, they likely would have been killed by the blunt force trauma sustained as the cabin continued to tumble. Even if someone had survived that, they still would have died when the crew cabin started coming apart a few seconds after 08:01.
The Columbia Accident Investigation Board Report concluded that NASA management was at fault for not paying attention to the warning signs of a possible problem and not taking steps to try to prevent foam loss on the ET, instead accepting damage caused by foam shedding as a normal part of shuttle operations. Put simply, NASA was playing a case of russian roulette. As with Challenger, there was a bullet in the chamber. It was a different bullet this time than Challenger’s SRB O-ring seal, but the results were the same.
It would be two and a half years before a shuttle was ready to fly again as NASA spent the stand-down period designing cameras to detect debris from the shuttle on ascent and new equipment to inspect its bottom once it reached orbit. Work was also done to minimize foam loss from the ET. New materials and repair procedures were developed in case heat shield damage was detected. Plans were also put in place to make sure a backup shuttle was ready to launch within a few weeks in case damage to a shuttle was too extensive and a crew had to use the ISS as a safe harbor. Even then, the ISS as a safe harbor wasn’t an available option for STS-107, since Columbia was in a completely different orbit from that of the ISS.
But a bigger change was in store for NASA’s long-term future. The administration of President George W. Bush (son of the elder George H. W. Bush) and Congress decided that shuttle flights would end by 2010. NASA would focus its efforts on design of a new capsule-based spacecraft called Orion as part of the Constellation program. Constellation would take crewmembers to the ISS, on missions back to the moon, and on to the planet Mars. The shuttle program was expensive to operate, with some inherent risks related to its configuration, while capsules on top of rockets were deemed to be safer. Future spacecraft would carry either crew or cargo but not necessarily both.
The shuttle would still continue to operate for the next few years, as its heavy-lift capabilities were needed to finish construction of the ISS. In 2006 NASA projected that it would need about twenty more flights to finish the station. While the work to complete the ISS was underway, NASA and its contractors started work on Constellation. Hopefully, if NASA had the budget it needed, the delay between the last shuttle flight and the first within the Constellation program would not be a long one.
Expedition 6
All these decisions about NASA’s long-term future were still far off in the days and weeks after STS-107 was lost. Aside from the loss of friends to each ISS crewmember, Columbia’s loss would also have a big impact on life aboard the station, both in the short-term and for the foreseeable future. While the ISS was new and in better shape than Mir was during the Shuttle-Mir Program, logistical resupply from the shuttle was no less important. Three people on orbit consume a certain amount of supplies while generating trash and waste. The station was in an unfinished state as well, with some of its equipment operating in temporary configurations only intended for a short period of time. The shuttle was also vital for periodic reboosts of the station’s orbit. While a Progress craft could reboost the station, a shuttle had bigger engines and carried a larger fuel reserve.
During the stand-down period, ISS program managers and engineers had to develop new procedures to help maintain the station in a semimothballed state until it could be supported by a shuttle once again. Naturally, this meant that STS-114 would not be coming up in three months to take the crew home. Instead, the current crew would have to return to Earth on the Soyuz. There would be a fair amount of work ahead for the Expedition 6 crew before they could return home. The next crew would also require some changes and retraining before flight, since they would have to launch on a Soyuz.
Staged EVAs
Thanks to delivery of the Quest and Pirs airlock modules the previous year, the ISS was no longer completely dependent on shuttles for assembly tasks. While EVAs conducted from the Russian side carried out important work, EVAs conducted from Quest were capable of doing more-complicated tasks. The shuttle-era EMUs allowed for more mobility. Russian suits operate at higher pressures, meaning less of a need for prebreathing to flush nitrogen from the blood. American suits operating at a lower internal pressure of 3.7 psi allow for easier movement and less fatigue. During early ISS space walks, EVA crewmembers would conduct brisk exercise while prebreathing pure oxygen to flush nitrogen from the blood quicker, but this would leave them slightly winded. When the Quest airlock arrived, EVA crews gained the option of camping out overnight in the airlock at higher oxygen levels at a slightly reduced pressure to flush nitrogen. So on EVA day, the amount of preparation time needed before heading outside was reduced.
In addition to the normal EVAs conducted by shuttle crews, station crews conducted what NASA calls “staged” EVAs. While the tasks were usually simpler than a shuttle assembly mission, staged EVAs were no less important, as they might involve tasks for getting ahead, such as relocating equipment already present, fitting small pieces of hardware, or cleaning up a previous work site. EVAs are not scheduled on a whim, as the tasks have to be critical for continued station operation and the risk has to be low before a space walk is authorized.
Expedition 6 crewmembers Ken Bowersox and Don Pettit conducted two staged EVAs. One was conducted in January, and the second one was conducted in April, after Columbia’s loss. The first one primarily involved removal of launch locks from a heat radiator on the main truss so that it could be deployed properly and removal of debris from a PMA on Unity. The second EVA involved reconfiguring electrical cables on the truss and fitting backup power cables to one of the gyros. They also replaced a power-control module and fitted a light fixture on to one of the truss’s Crew Environment Translation Aid carts. These carts act in a manner similar to a railcar and would allow the SSRMS or other equipment to be moved to the ends of the truss just short of the main solar arrays once the truss was fully completed.
Don Pettit and Saturday Morning Science
Nikolai Budarin was a typical Russian civilian cosmonaut. He spent two years in the Soviet Army in the 1970s before getting his degrees in aircraft and electrical engineering and joining NPO Energia in various postings. Prior to Expedition 6 he had also been part of two expeditions to Mir late in its lifespan, and his engineering background came in rather handy for its maintenance.
Ken Bowersox, on the other hand, was the stereotypical American astronaut of the shuttle program. He was an Eagle Scout, a graduate of the U.S. Naval Academy with a degree in aerospace engineering, a naval aviator, and a graduate of the U.S. Air Force Test Pilot School at Edwards before joining the astronaut corps in 1987 as a shuttle pilot. He was also a navy captain. He flew two shuttle
missions as a pilot and two more as a mission commander.
Compared to those two men, Donald Pettit was a unique individual. Selected as an astronaut in 1996, Pettit had been assigned as a backup for Expedition 6, but he was moved up to prime crewmember when original Expedition 6 science officer Don Thomas was medically disqualified after an issue cropped up during a preflight physical. Pettit was a smart individual with kind of a thin build. Like Bowersox, he was also an Eagle Scout, and he had a love of the outdoors, having grown up in Silverton, Oregon. He had a degree in chemical engineering and a doctoral degree from the University of Arizona before working for the Los Alamos National Laboratory. He had the smarts, but he was still a rookie astronaut on his first assignment.
Don Pettit also had a unique curiosity for how things work. Back on Earth, he set up a laboratory in his garage to do scientific experiments on his days off. A self-described “übernerd,” as it were, Don Pettit is almost like a cross between Don Herbert’s classic television persona Mr. Wizard and fictional television scientist MacGyver, with some Bill Nye the Science Guy thrown in for good measure. While he didn’t have the looks of Richard Dean Anderson’s character MacGyver, Pettit was just as creative. In one case, Pettit took three of the crew’s personal CD players and used them for an experiment in gyroscopic properties. One CD player with a CD spinning in it just tumbles. Two taped together at ninety-degree angles from one another are more stable, but the assembly still tumbles in one direction. Tape a third CD player to the others at another ninety-degree offset, and the resulting creation is rock-solid stable. Pettit used his new creation as a flashlight holder while doing maintenance inside access panels in the Destiny laboratory.
