FTV: Challenger 40 Years On
Over the decades it has existed, January has been a hard month for NASA (followed closely by February). Sadly, the loss of the Apollo 1 crew during a training session on January 27, 1967 marked the first mission related fatalities for the United States manned space program. The Apollo 1 accident took place during what was known as a ‘plugs out’ simulated mission. The test was being conducted on a Friday at the end of a long, exhausting week. The launch pad fire that erupted in the capsule claimed the lives of Gus Grissom, Ed White, and Roger Chaffee. Astronauts Elliot See and Charles Bassett were on route to the McDonnell Aircraft Corporation in St. Louis eleven months earlier when their T-38 jet struck the roof of the plant. Both were killed on impact, but their deaths did not happen during training or an actual mission.
The Apollo 1 fire was blamed on what became known as ‘go fever’. In their haste to get Apollo off the ground, there were short cuts taken to try and reach the Moon by the end of the 1960s decade. Lack of oversight coupled with plain old sloppy construction methods doomed the crew before the craft was even ready to fly. It was a deadly combination of things that killed the crew which in turn could have led to the whole program being scraped.
The death of the three astronauts sounded warning bells that made NASA pause for a complete re-evaluation of the Apollo program. When the problems were identified and corrected, all the folks at NASA, from the nuts and bolts assembly crews to the highest levels of management, came to the same conclusion. Had they carried on with the slip-shod work that went into the first Apollo capsule design, NASA would no doubt have lost their first crew in space if that version of the ship had been put into orbit.
February 1, 2013 marked the second loss of a crew during a mission. Shuttle Columbia broke apart returning from 16 days in space, brought down by damage that had occurred to the leading edge of its left wing just 81.9 seconds after it left the launch pad. A piece of insulating foam broke off the ‘bipod ramp’ that connected the shuttle to the external fuel tank. At the speed they were already traveling, it punched a hole in the reinforced carbon-carbon panel on the leading edge of the shuttle’s wing. On their second day in orbit, an attache case sized object was seen drifting away from the orbiter. The crew had no way of knowing a ten inch hole had been opened in the wing that would allow super heated gas to penetrate the craft upon re-entry.
Columbia lost attitude control and disintegrated some 200,000 feet over Texas and Louisiana, dooming the seven person crew. The launch pad cameras had recorded pieces of foam breaking off the tank struts on previous flights, but nobody gave them much thought. The idea that ‘it is just foam insulation’ was put to the test by using an air canon to fire various size chunks of the material at segments of a wing panel. The data revealed that these ‘light, airy chunks of foam’ carried quite a wallop at launch speeds and could (and did) indeed damage the orbiter. The loss of Columbia caused another shuffle in NASA’s procedures. The agency enacted new policies that directed the shuttle crews to examine (in orbit) the Shuttle using a camera mounted on the mechanical arm mounted in the payload bay. Though it was never needed, a contingency plan was put in place to rescue any crew stranded by any future damage to the vehicle.
It was the loss of the Space Shuttle Challenger on January 28, 1986 that shook NASA to the core. Apollo 1 was the end result of the ‘get it done no matter what it takes’ attitude that the Moon landing program created. ‘Go fever’ cost three men their lives. Columbia happened because nobody considered that the ‘light, airy chunks of foam’ breaking off the bipod struts could pose any danger to the orbiter. This mistake came at the cost of seven more lives. Although the Challenger accident also doomed seven souls (five astronauts, Greg Jarvis, a technician and the first ever teacher in space, Krista McAuliffe), it was different. In his book Challenger: A True Story of Heroism and Disaster on the Edge of Space (Avid Reader Press, 2024), author Adam Higginbotham lays out the premise that this accident was one that could have (and should have) been prevented.
When the space shuttle program was first envisioned, it included a large transport ship that would take a smaller orbiter to the upper atmosphere where it would then complete the trip to orbit. Both the transport and the orbiter would fly back to Earth to be refitted for the next mission. When the Air Force insisted the orbiter be large enough to carry bus-sized spy satellites into space, the size of the shuttle grew beyond what the engines would be able to lift. This new design was the reason solid fuel rocket boosters (SRBs) were added to the vehicle. Solid fuel rockets had been used before, but never for manned flights. Once the SRBs were ignited, there was no way to throttle them down which put severe limitations on any form of escape plan for the crew should an emergency happen in the first minutes after liftoff.
The SRB contract was awarded to Thiokol, a company based just outside of Salt Lake City, Utah. These boosters were much larger than most conventional solid fuel rockets in use. They were so large, they had to be transported to Florida in segments and assembled to their full length at Cape Kennedy. The 13 foot diameter cylinders were packed with a rubbery fuel that was formed with a long conical opening from the base to the top end. When it was time to ignite the SRBs, a kind of flame thrower would shoot a 150 foot long flame up the opening to ensure even combustion. During the design phase, the SRBs were tested on the grounds of the Thiokol plant and then disassembled to see if the joints were performing as expected. To ensure no hot gas escaped the interior, each joint contained two O-ring gaskets made from a composite rubber compound sealed in place with heat resistant putty.
During a Shuttle launch, the SRBs were jettisoned from the large external fuel tank and picked up by two recovery ships after they had parachuted back to the ocean. They would be towed back to Florida and a team would disassemble them and examine the joints between segments for any signs of damage. After an early Shuttle flight, they discovered that there had been some leakage (called blow by) of the seals on one segment. It was determined this happened in the first seconds after the SRBs were ignited when the internal pressure deformed the casings. As long as the primary and secondary O-rings sealed again, it was deemed that some blow by was an acceptable risk. It was telling that when the damage was first noticed, it occurred when the launch took place under the coldest temperature of any previous flight. The damage was noted and the segments were sent back to Utah to be refitted for another flight.
Some of the engineers at Thiokol were alarmed when they found out there had been erosion on some of the segment O-rings. They proposed more testing to see if this was going to be a chronic problem that needed more scrutiny. The Shuttle program managers at NASA were feeling under the gun trying to reach what was beginning to seem like an impossible goal: to launch Shuttles on a regular schedule. Thiokol was under pressure to keep SRBs rolling off the assembly line. The concerned engineers felt the safety aspect of their job was being given short shrift. Thiokol was acquired by the company that manufactured Morton Salt but the schedule to grind out more SRBs didn’t change..
Morton Thiokol engineers Roger Boisjoly and Allan McDonald were very vocal about the reported damage to the O-rings. Boisjoly in particular was prone to getting a bit prickly when their concerns were not, in his mind, addressed. He badgered the company enough to get a detailed study of the joint problem approved and had begun exploring design changes. With the increased demand for SRB production, the studies kept getting delayed. Boisjoly wrote a comment in the margin of his working notes that simply said, ‘loss of life’.
Serious discussions about the O-ring problems were circulating among the MT engineers as early as 1984. At first, some charring of the first seal was attributed to air bubbles in the putty used to cover the joints. The air bubbles allowed some burn through to the first O-ring, but they were confident the second O-ring would keep the joint secure. It was determined that the putty was kept in cold storage before application and the procedure was changed to ensure the material was warmed before application.
Before each flight, a group representing all departments involved would meet at the Cape and give a ‘go / no-go’ assessment to approve the next launch. The O-ring problems were noted but checked off on the list as an ‘acceptable risk’ and not enough of a concern to prevent the shuttle from flying. Managers from both NASA and Morton Thiokol were instrumental in downplaying the risk and the flights continued even though the engineers studying the problems were not happy with the pace of the investigation. When Challenger was launched on its fatal flight, the engineers in Utah had warned that the unprecedented cold temperatures dictated the flight be delayed. In fact, they recommended that the shuttle not be launched below a temperature of 53 degrees F. The overnight temperature for the Challenger launch dipped to a frigid 18 degrees F! After a 30 minute offline caucus at Morton Thiokol, the senior managers there overruled this decision and gave the go-ahead for the launch. The engineers who were overridden felt that by ignoring their recommendation, the seeds of the disaster were planted.
When the Rogers Commission began investigating the accident, those most responsible for the launch taking place (against advice of those who knew better) tried their best to defend the decision to launch. Using what commissioner Richard Feynman called ‘fantastical numbers’, the managers who were questioned about the reliability of the Shuttle tried to paint a rosy picture. They said the odds of a failure of this magnitude in a Shuttle would be ‘1 in 100,000’. In other words, they would only expect to have one Shuttle failure even if they launched one every day for 274 years. A poll of the engineers involved rated ‘chance of failure’ anywhere between 1 in 50 to 1 in 200. In reality, two failures in 135 Shuttle flights put the number at a more realistic 1 in 68.
The commission’s final report cut through the bureaucratic fog and laid the blame squarely where it belonged. Their findings might not have come to light without some backdoor dealings between the engineers and the commission. One of the committee members, astronaut Sally Ride, was the lynch pin in uncovering the truth. Ride had been given documentation that NASA had prior knowledge of the risk of failure in the solid booster rocket O-rings that ultimately doomed Challenger. She in turn, shared this information with fellow commission member Richard Feynman. Feynman was a renowned theoretical physicist who had won the Nobel Prize in Physics in 1965. Commission head Rogers called Feynman ‘a real pain’, because he was a bit of a maverick who did not suffer fools lightly nor did he strictly follow the agenda set by the commission.
During one of the commission’s televised sessions, Feynman confronted the NASA and Morton Thiokol higher ups about their claims that the weather played no part in the accident. Feynman dropped a piece of the O-ring material introduced as evidence into a glass of ice water. After a few minutes, he took out the O-ring material and compressed it. He made the point clear to all – the cold conditions kept the compressed O-rings from expanding to fill the SRB connection points. This allowed the blow by that doomed Challenger. By providing Feynman with her inside information, Sally Ride made sure this information came to light in the hearings. The findings of the Rogers Commission changed the lax oversight culture at NASA that had led to the loss of Challenger and its crew.
The Rogers report detailed that both NASA and Thiokol had known about the O-ring problems as far back as 1977. Not only had they known about the problem, they knew it had the potential to cause just the sort of catastrophic failure that brought Challenger down. The Report called it ‘an accident rooted in history’. There were many members of the Flight Readiness Review (FRR) team at NASA who could have stopped the launch, but for some reason they had decided not to do it. The management structure at NASA lacked a system of major checks and balances and in the case of the Challenger accident, it proved to be a fatal scenario.
The Rogers Report concluded that: “…failures in communication … resulted in a decision to launch 51-L based on incomplete and sometimes misleading information, a conflict between engineering data and management judgements, and a NASA management structure that permitted internal flight safety problems to bypass key Shuttle managers.” Feynman summed up the whole affair in his 1988 book Do You Care What Other People Think? The second half of the book talks extensively about the Challenger accident where he said, “For a successful technology, reality must take precedence over public relations, for nature can not be fooled.”
Top Piece Video: We just finished talking about Paul McCartney in our last FTV so the foolish decisions mentioned above make this appropriate: