Remembering Challenger

Science

15 March 2019
Article
Auteur(s): Philip Lepoutre
In remembrance of an event of catastrophic magnitude that shook the world.

The Challenger Disaster happened on the 28th of January 1986 and left the world speechless and in disbelief. People emptied their souls of any belief that the Shuttle Program was a viable solution to understanding our place in the universe. The consequences went far beyond the disaster.  People who worked on the mission resigned, fell into depression, and took their own lives due to unbearable guilt. This day also marked the first time in history when public interest in space fell dramatically, leading to budget cuts and a loss of interest to innovation in the aerospace industry.

Not only was the 51-L Space Shuttle mission special because it aimed to launch revolutionary satellites into space but it was also the first time in history that a private non-astronaut citizen joined a space mission.

Fig.1: Astronauts who sacrificed their lives in the name of science

Fig.2: Challenger Space Shuttle

In the midst of the Cold War, the United States announced the start of the “Teacher In Space Project”, an initiative launched to inspire students, honour teachers, and spur public interest in mathematics, science, and space exploration. NASA wanted to find an "ordinary person," a gifted teacher who could easily communicate with students about these subjects while in orbit. NASA hoped that sending an ordinary teacher into space would increase public interest in the Space Shuttle program and also demonstrate the reliability of space flight at a time when the agency was under immense pressure to find financial support. President Reagan said it would also remind Americans of the important role that teachers and education serve in the country.

Fig.3: Christa McAuliffe, pictured here while training on the “Vomit Comet.” Her death following the Challenger disaster shocked the American public, who had fallen in love with her manners and composure.

More than 40,000 teachers across the United States came together and participated in this competition, but only one was chosen to fly aboard the Challenger Space Shuttle. Her name was Christa McAuliffe. As she watched the Space Age take birth, she couldn’t help but be inspired by immense projects like “Project Mercury” or the “Apollo Program”, which brought more than 500,000 US mathematicians, physicists, biologists, scientists, and engineers together. The sixties to eighties was the golden age of space travel and new space innovations made headlines every week. Everyone in school knew about them. We reached a point where it wasn’t necessary to convince students that being an engineer was cool because this idea was already ingrained in our culture.

Unfortunately, a tragic event caused the demise of mission 51-L, and interest in funding the American Space Program dropped.

What actually happened on the launch day?

Fig.4: This photo provided by NASA from Jan. 28th, 1986, shows icicles on the handrails of the space shuttle Challenger’s service structure on the morning of its final launch from Kennedy Space Center.

On January 24th, 1986, it was a very cold day with gusty wind. Due to the inclement weather, the launch had to be rescheduled for the 26th of January. On this day, during precheck, some anomalies in sensors were found, hence delays seemed inevitable, but pressure on NASA to go ahead with the launch was building. Forecasts predicted an unusually cold morning on the 28th of January, the new launch day, with temperatures close to -1°C, the minimum temperature permitted for launch.

Many mechanical components which had no back-up if they failed, like the rubber O-rings that sealed the booster rockets on the side of the Space Shuttle, had no data on how they would perform at such a low temperature. In addition, many engineers from Morton Thiokol (the manufacturer of the side booster rockets), particularly Roger Boisjoly, expressed deep concern about a possible O-ring failure in cold weather and recommended postponing the launch. (Rubber behaves unusually when exposed to low temperatures and as the temperature continues to drop, rubber gets stiffer, which could fail to seal the booster joint properly and increase the likelihood of creating a gap.)

The pressure to move forward with the launch was too high and despite the back and forth between NASA executives and engineers, NASA decided to proceed with the launch on the morning of the 28th of January, 1986.

As the shuttle launched, the first indicator of a major malfunction was a plume of black smoke, coming from the tightly sealed joints of the right booster rocket. At an altitude of around 11km-15km, most rockets encounter a period called max-Q, also known as the period of maximum aerodynamic pressure. It is the moment when the rocket is subjected to the highest “stress”, due to strong wind and other factors.

Precisely 58 seconds after launch, as Challenger reached max-Q, an leak opened in the rocket joint. 73 seconds after launch, the leak expanded so dramatically that it penetrated the link between the booster rocket and the main fuel tank, which opened a wider hole, and tore everything apart. As hot gases from the side booster rocket entered the main fuel tank, the shuttle burst into flames and a series of chemical reactions caused it to explode, burning more than 2 million litres of fuel in a matter of seconds. If the seal would have lasted just a little longer, the booster rockets would have separated from the main fuel tank and the safety of the crew would not have been compromised. Although this explosion was catastrophic in nature, NASA discovered that at least three of the astronauts were still alive after the explosion. NASA later found that their personal air packs, which they were instructed to activate only in case of emergencies, had been activated. However, plummeting to the ocean at a speed of over 333km/h had sealed their fates.

Fig.5: The tragic explosion of the Challenger Space Shuttle.

Fig.6: At 58.778 seconds into powered flight, a large flame plume was visible, indicating a breach in the motor casing.

This disaster could certainly have been avoided. The issues with the rubber O-rings were well documented by the engineering teams working on the Booster Rockets, but the management’s decision to proceed with the launch took precedence. With immense pressure from NASA, Thiokol management had approved the launch. Organizational bureaucracy, including a failure in communication and a management structure that allowed NASA to bypass safety requirements, led to the Challenger disaster.