Curio Cabinet

On this day in 1986, the U.S. was in mourning. One day earlier, on January 28, the space shuttle Challenger had exploded after takeoff, killing all seven crew members aboard. Most Americans were in shock…but not engineer Allan J. McDonald. He had known that there were potentially deadly problems with the Challenger, and had tried to delay its launch. After the tragedy, McDonald and other like-minded engineers worked to expose those at NASA who had insisted on pressing forward with the launch in spite of safety concerns.
 
Born on July 9, 1937, in Coding, Wyoming, McDonald began working for Morton-Thiokol, Inc., a company specializing in rockets and propulsion systems, in 1959. He served as leader for all of Morton-Thiokol’s flight tests launched out of Cape Canaveral, Florida, where he would check the condition of missiles before they were launched for testing. In 1973, Morton-Thiokol was contracted by NASA to create solid rocket boosters for their space shuttles. McDonald led a team which assessed shuttles before their launches from Kennedy Space Center in Merritt Island, Florida. It was up to McDonald to sign paperwork approving or disapproving each launch. He didn’t have the final say in whether launches moved forward, however. His opinion was considered alongside that of other engineers.
 
The space shuttle Challenger was built in 1983. Over its three years of service, it completed nine successful missions. Its tenth mission, designated STS-51-L, was originally scheduled for July, 1985. Assigning the crew took longer than anticipated, though, so the launch was rescheduled for November of that year. However, changes to the shuttle’s weight necessitated another delay, leading to the launch being set for January 28, 1986. Throughout the ongoing delays, McDonald and other engineers were tasked with inspecting Challenger, and they weren’t comfortable with what they found. The cold January weather made McDonald concerned about the O-ring seals in the shuttle's solid rocket booster joints. These O-rings were made from rubber, and were supposed to seal together joints in the boosters. Cold weather caused the rubber to stiffen. McDonald knew that this could lead to unsealed joints, and leaks of pressurized gas. Bob Ebeling, Arnold Thompson, and Roger Boisjoly, fellow engineers from Morton-Thiokol, agreed that the O-rings posed a serious problem. They, along with McDonald, told Morton-Thiokol officials of their concerns.
 
Unfortunately, pressure surrounded the mission. After all, Challenger’s launch had already been delayed, and the mission was highly-publicized due to the inclusion of school teacher Christa McAuliffe, the crew member meant to be America’s first civilian astronaut. When Morton-Thiokol brought their engineers’ concerns to NASA, they were dismissed. Days before launch, Morton-Thiokol asked McDonald to sign and submit an official form stating that the Challenger was safe to launch. He refused, but the launch moved forward anyway.
 
73 seconds after Challenger’s launch, the O-ring seals on the shuttle’s right solid rocket booster failed, having stiffened from the cold weather. Hot, pressurized gas from the boosters leaked through joints and into an external propellant tank. This caused an explosion and threw the shuttle into a rotation at nearly 1,500 miles per hour. It was ripped apart by aerodynamic forces, killing all seven crew members aboard. McDonald watched the tragedy unfold from Cape Canaveral.
 
Days later, he traveled to Washington D.C. to participate in the Rogers Commission, a Presidential Commission meant to uncover the reasons behind the launch’s failure. McDonald listened as NASA officials failed to acknowledge his concerns leading up to the launch. Finally, he interrupted an official’s testimony by raising his hand to speak. He informed the commission that he and other engineers had recommended against the launch, refused to sign off on it, and had even sent NASA a letter of concern regarding the O-rings. The focus of the commission immediately shifted to focus on procedural failures at NASA. Afterward, Morton-Thiokol retaliated against McDonald by demoting him and several other engineers, including Roger Boisjoly. Boisjoly reported this to the commission, and Congress threatened to bar Morton-Thiokol from future federal contracts unless they reversed the demotions. In 1988, McDonald was placed in charge of creating new, safer rocket boosters for future shuttle launches.
 
Even after his retirement in 2001, McDonald remained committed to safety. He became a speaker on ethics and decision making, addressing engineers on the importance of both. Prior to his death in 2021, he donated his personal papers regarding the Challenger launch to Chapman University in the hope that they could prove useful to future researchers. No doubt they contain just as many lessons about leadership and heroism as they do about engineering.

 
[Image description: Allan J. McDonald gestures as he speaks at a conference in 2012.] Credit & copyright: NASA, Sean Smith, Wikimedia Commons, Public Domain

Get Hilary Swank and Aaron Eckhart on the phone—the Earth’s core is acting up! In an event that mirrors the 2003 sci-fi B-movie The Core (rated 5.5 out of 10 on IMDb), the Earth’s molten iron core has stopped rotating before shifting gears, according to a paper published in the journal Nature Geoscience by geophysicists from Peking University. Fortunately, this isn’t a portend of the end of the world like in the movie (39 percent on Rotten Tomatoes). In fact, the core is already rotating, just in the other direction. The spinning core of the Earth acts as a dynamo that creates a magnetic field, protecting its surface from dangerous radiation from outer space, but it’s not as consistent or unchanging as it would seem. Furthermore, the core has never completely stopped—it just slowed down in relation to the mantle. One of the authors of the paper, Xiaodong Song, stated, “We see strong evidence that the inner core has been rotating faster than the surface, [but] by around 2009 it nearly stopped. Now it is gradually mov[ing] in the opposite direction.” Song and his colleague went back to records of seismic waves dating back to the 1990s to determine the rate of the core’s rotation. By tracking the rate at which repeating earthquakes travel through the inner core, they found that the core was rotating slightly faster than the mantle and the surface. But that difference began disappearing around 2009 before reappearing—except this time, the core seems to be rotating in the opposite direction. The researchers inferred from their data that this may be part of a 70-year cycle, with the direction changing every 35 years or so. It’s enough to make your head spin.

[Image description: An illustration showing the layers of the earth, with the core represented as a yellow ball.] Credit & copyright: ArtsyBeeKids, Pixabay