An Explanation of NASA's Space Shuttle Columbia Disaster
On January 16th, 2001, the Columbia space shuttle launched for the 27th and last time on a mission to perform various experiments, including investigating the effects of microgravity on the human body.
It was a joint mission with Israel and included Israeli astronaut Ilan Ramon, a move made to foster support for further international space missions. After having successfully completed their experiments, the shuttle attempted to re-enter the atmosphere, only to reach the ground in pieces spanning 200 miles across Texas, Louisiana, and Arkansas. What caused this is the direct reason that NASA ended their space shuttle program in 2011.
The immediate cause of the Columbia accident--foam insulation impact damage to orbiter--was mostly solved after the accident. The retirement in 2011 was due to budgetary and long-term risk to future crews, flying without a capable crew escape system.
They key to understanding the cause of the disaster occurred fewer than 90 seconds into the launch.
To better understand the problems associated with Columbia's landing, a basic understanding of the space shuttle's anatomy is needed. Beginning with the Challenger Space shuttle, which also ended in disaster and took the lives of 7 astronauts, NASA began to insulate their shuttles with spray on foam. The external tank was always insulated with spray-on foam, part of the shuttle's original design. Challenger was lost due to a booster design flaw and bad decision-making.
The shuttle had a massive capsule, this was the external, liquid fuel tank containing liquid O2 and H2, the propellant supply for the 3 main engines. containing supercooled hydrogen and oxygen to aid in propulsion during takeoff. Hoping to curb the potential for fragments to fall off, they sprayed foam on in compromised areas. An unintended side effect was the dried foam shooting off at a high velocity during launch. The foam insulation was always sprayed on over the entire tank. The problem was that fragments of this foam from the tank would fall off and strike the orbiter hanging on the side of the tank. Unfortunately it fell off due to trapped air under the foam expanding. But as it fell it could strike the orbiter at speeds of several hundred miles per hour.
Post launch, multiple photographs were analyzed and one such revealed a solid brick of foam around one foot by 2 feet, striking the left wing of the shuttle at around 500 miles per hour about 82 seconds post-launch.
Team managers at NASA were alerted to this impact, and reviewed the footage the next day, only to decide that the damage was not significant enough to cause any problems. In a routine meeting assessing potential damage of the shuttle on day 5 of the mission, NASA engineer Rodney Rocha knew that this had potential to become a larger issue.
Rodney requested, at least a dozen times, for American satellites to produce images of the damage caused; but several NASA managers--not the flight director--turned down the imagery requests. shut down these requests and considered it to be “a dead issue”.
Taking it a step further, Rocha emailed the shuttle engineering office, requesting the astronauts be contacted to make a visual inspection of the damaged wing. He received no response. 8 days into the mission, the crew was alerted via email of the debris strike, but were told it was no concern for worry, and that they wanted to give them a heads up in the event a reporter asked them about it on landing.
Rocha later received a response from the manager shuttle engineering office saying that he “wasn't going to be chicken little about this”.
The issue of foam breaking off was not exclusive to the Columbia launch, occurring on various shuttle launches before, and the shuttle engineering office maintained that because of the prior incidents resulting in successful missions, no further imagery or examination was required of Columbia, and at most would need minor repairs upon landing.
This is called "normalization of deviance", where you get used to a potentially catastrophic situation when it does not result in disaster. This human mindset also resulted in the Challenger accident.
Rocha and others attempted numerous times to report the issue to Linda Ham, manager of the mission management team, but she denied 3 separate requests for images of the damaged tiles, stating it would take too much time. NASA at the time was described to have a “broken safety culture” that prioritized the mission and it’s publicity over minor concerns. Midway through the mission, Ham led a meeting where engineers from Boeing acknowledged the issue but stated there was no major damage to the Columbia Shuttle.
Boeing trusted its debris impact model, but its assumptions were incorrect, and led managers to a false sense of safety. In fact the model applied to heat shield tiles, not the leading edge panels of the wing.
Upon re-entry, temperature sensors in the damaged left wing had stopped giving readings. Superheated gasses burned through the shuttle causing the wing failure, which, when it occurred, sent the orbiter out of control within seconds. (Read about that sequence in the Gehman commission report) The Columbia Accident Investigation Board (CAIB) was formed, and Rocha was invited to join the team. Around 40% of the pieces of the shuttle were recovered including footage from the inside during re-entry.
CAIB released a report following the incident and issued the following “There were lapses in leadership and communication that made it difficult for engineers to raise concerns or understand decisions. Management failed to actively engage in the analysis of potential damage caused by the foam strike.” They had also determined, if NASA had been alerted to the problem soon enough, that there was the potential for either a repair or a rescue mission, aided by the Atlantis, a second shuttle set to launch soon after.
Bringing Columbia Home makes the point that, yes, a rescue mission could have been considered, but NASA would have had to declare a rescue on the second day of Columbia's mission to have time to succeed. NASA, even with perfect decision-making, did not have the confirming damage information by then to make that crucial decision.
In the wake of the disaster, the CAIB also stated that NASA’s culture must change, and can do so under solid leadership. The shuttle program was suspended for two years. Shuttle flights encountered the foam issue time and time again after, and following the completion of the International Space Station the program was disbanded in 2011. However, the liberated foam was small, so small that it was incapable of causing heat shield damage. While imperfect, that technical solution worked. It was the potential for some other unanticipated accident cause, and the absence of a crew escape system, that led managers to retire the shuttle.
No manned spacecrafts have launched on United States soil until this past May when SpaceX launched the Crew Dragon Demo-2.