40 years after Challenger disaster, NASA faces safety fears on Artemis II

Forty years ago today, disaster struck NASA’s human spaceflight program when the Space Shuttle Challenger exploded 73 seconds after takeoff, killing all seven people on board.

The tragedy nearly ended the shuttle program prematurely. Decades later, the mistakes that led to Challenger disaster, as well as the fallout from the similar loss of the shuttle in 2003 Colombiaoccupy a particularly important place at a time when NASA seeks to launch four astronauts on the ambitious Artemis II mission around the moon starting next week.

The mission will be the first crewed flight of the massive Space Launch System (SLS) rocket and Orion capsule, as well as the first time humans have left Earth’s orbit since the last Apollo mission in 1972. NASA has already faced public scrutiny for its handling of the unexpected behavior of Orion’s heat shield – crucial equipment for protecting astronauts when they return to Earth – during an uncrewed orbital test flight in 2022.

On supporting science journalism

If you enjoy this article, please consider supporting our award-winning journalism by subscription. By purchasing a subscription, you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

NASA believes that the changes made as a result of Challenger and other disasters in its history are enough to keep Artemis’ crews safe. “Challenger…brought out aspects of the agency that hopefully no longer exist and that we’re still working to address,” says Tracy Dillinger, safety culture program manager in NASA’s Office of Safety and Mission Assurance. “Space is risky. We know that, and our astronauts know that. We just want to be smart about the risks we accept.” Currently, Orion’s heat shield is widely considered the greatest risk to the crew; NASA said this concern was addressed by changes to the Artemis II flight path.

From routine to disaster

The 1986 Challenger The disaster occurred during mission STS-51L, the 25th flight of NASA’s shuttle program, which was approaching its fifth anniversary. During the week-long mission, the crew had an eclectic schedule: observing Halley’s Comet and deploying both a communications satellite and an astronomical instrument into Earth orbit, but most notable was one of its crew members, Christa McAuliffe.

McAuliffe had taught middle and high school and was selected to fly after a national “Teacher in Space” competition. She planned to teach two lessons from orbit, and her inclusion was part of a broader NASA campaign to present shuttle spaceflight as an ordinary, low-risk activity in which non-astronauts could participate.

“It’s a kind of multipurpose vehicle that astronauts themselves often call a space truck,” says Jennifer Levasseur, a space historian and curator at the Smithsonian Institution’s National Air and Space Museum. “The space shuttle is supposed to be very regular, it’s supposed to be routine, it’s supposed to be safe, so safe that the astronauts don’t even have to wear spacesuits.”

On that cold morning in late January, thanks to the excitement over McAuliffe’s flight, some 2.5 million students nationwide watched the launch, only to see the disaster unfold on live television. The so-called O-rings that connected the cylindrical segments of one of the shuttle’s solid rocket boosters ruptured in launch conditions far colder than they were designed for. Just over a minute after ignition, the booster rupture caused the shuttle’s giant external fuel tank to explode, tearing the vehicle to pieces over the ocean and dooming all seven astronauts.

Engineering safety culture

With the world watching, NASA struggled to understand what went wrong and how to fix it, while engaging in a deeper debate: Was human spaceflight still worth the risk of catastrophic loss? Although NASA rejected calls to end the Space Shuttle program, it suspended flights for nearly three years while it studied NASA data. Challenger disaster.

With charts, graphs and dense technical writing – in a report that spanned more than 200 pages, not including its 15 appendices – NASA officials deconstructed the failure. This document highlighted not only the thermal constraints of the O-rings, but also the inherent design limitations of the shuttle and the sociological pressures surrounding the program that put those O-rings in place and moved the launch forward.

“It was very obvious on several missions prior to STS-51L that there was a problem with the solid booster sections and the way they fit together,” says Levasseur. Some safety concerns were even raised before a shuttle flight. And on the morning of the launch, when an engineer expressed concern about O-rings in cold weather, program managers who wanted the agency to successfully fly shuttles regularly decided to let the launch proceed anyway.

“Despite all this knowledge, NASA continued,” says Levasseur. “His management said, ‘We have a schedule.’ This “launch fever” or “start fever,” along with the recurring O-ring anomalies that prompted managers to ignore them, appeared to be the company’s real downfall. Challenger. The extreme cold caused the O-rings to fail, but NASA’s culture was just as blameworthy and in need of more urgent modernization than any piece of hardware on the shuttle.

Smaller versions of NASA’s Challenger The investigation is happening today, says Sandra Magnus, a part-time professor of engineering practice at the Georgia Institute of Technology and a former NASA astronaut who previously served on NASA’s Aerospace Safety Advisory Committee. “Whenever there is an accident, whether it is something huge like Challenger or something a little less life-threatening, NASA has a process to go through to try to understand what happened and why it happened,” she says.

Artemis’ ambitions

NASA is now facing its first crewed trip beyond Earth’s orbit since 1972, and numerous iterations of the agency’s safety investigation processes have taken place throughout the launch process to protect four astronauts: NASA’s Reid Wiseman, Victor Glover and Christina Koch and the Canadian Space Agency’s Jeremy Hansen. They will be the first humans to launch on the SLS megarocket and its Orion capsule, and if all goes well, they will set a record for humans reaching the greatest distance from Earth.

Some worry about their fate when they return home, when their capsule will have to re-enter and cross the Earth’s thick atmosphere, enveloped for many painful minutes in a ball of fire ignited by friction. Orion is of course equipped with a heat shield, which combines updates based on knowledge from Apollo and the Space Shuttle program, notes Levasseur.

While examining the Orion capsule that flew on the uncrewed Artemis I mission in 2022, NASA officials noticed that huge pieces of its heat shield had exploded unexpectedly. It’s a problem that engineers have studied in the years since the test flight, and they say that adjusting Orion’s trajectory toward Earth — a faster dive into the atmosphere with a steeper slope instead of a shallower, more prolonged descent — should help avoid this problem.

But this is not the same as rethinking the heat shield, and the agency chose not to test the heat shield on this new re-entry profile before committing. Artemis IIThe astronauts participate in it. According to NASA officials, rethinking the heat shield would have caused too many delays and a new re-entry test was deemed too costly.

It would be difficult for an observer to determine whether this choice reflects a launch fever that once again violates procedural norms. Artemis is a massive program — NASA estimated in 2024 that its costs since October 2011 would reach $93 billion by October 2025 — and one that can inherently exert pressure to move things forward, says Jordan Bimm, a space historian at the University of Chicago.

And NASA must juggle many pressures. “NASA has never had a moment like this before,” Bimm says. In spaceflight, the agency juggles negotiating multibillion-dollar contracts with commercial giants such as SpaceX and Blue Origin while competing with spaceflight newcomers, such as China and India, which are pursuing their own crewing ambitions.

The agency set what experts consider a promising example during the Artemis I mission, which was repeatedly delayed, even going so far as to move the massive rocket off the launch pad to shelter it from a hurricane.

To Levasseur, this suggests that current NASA leaders will make difficult choices to ensure the safety of their crews. “These are children or young people from the 1980s, who were inspired by the first space shuttle flights,” she says. Many, like her, were shaped by watching the Challenger disaster in childhood, or later Colombia tragedy. “Those memories are there, and they won’t want to make the same mistakes they did before.”