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The Challenger space shuttle is transported to the launch pad in December 1985, about a month before the fateful launch. (Credit: NASA)

On Jan. 28, 1986, NASA’s Challenger space shuttle disintegrated 73 seconds after launching from the Kennedy Space Center. All seven crew members aboard, including Â鶹Ãâ·Ñ°æÏÂÔØBoulder alumnus Ellison Onizuka (AeroEngr ’69), tragically lost their lives.

David Klaus, professor emeritus from Â鶹Ãâ·Ñ°æÏÂÔØBoulder’s Ann and H.J. Smead Department of Aerospace Engineering Sciences, started his career with NASA and was a shuttle launch control engineer at the time (although he did not work the Challenger mission).

Â鶹Ãâ·Ñ°æÏÂÔØBoulder Today spoke with Klaus about his memories of that day, the legacy of the crew and crucial lessons learned from the tragedy.

Where were you on the day of the Challenger incident?

NASA had plans to start launching Air Force payloads off the West Coast at Vandenberg Air Force Base in California in July of 1986. I was training to be on the Vandenberg launch team, and I would have been on the Challenger launch console, but I had just gone out to California for some work out there. So I was at the Vandenberg launch site when the Challenger launched from the Kennedy Space Center in Florida.

We happened to be sitting in the launch control center at Vandenberg. We pretty much saw what everybody else watching TV saw, although we could hear the comms loops. We could hear what was going on.

When did you realize that something was wrong?

All I saw was that infamous image with the solid rocket boosters going off in two directions. I was pretty new in the game at that point, so I didn't have a lot of insight. But I was sort of in disbelief at first. You don't really comprehend what you're seeing. It just doesn't look right. Something looks wrong. Your brain’s trying to process what's going on. But we realized pretty quickly that this was a bad event.

What caused the shuttle to break apart?

The actual root cause of the failure was the O-rings (gaskets) that keep the propellant pressure contained inside the two rockets. It was really cold in Florida that day, and my understanding is that the cold weather made the seals brittle. Because they were brittle, they allowed gas pressure to escape, and the escaping gas pressure is ultimately what caused the destruction of the vehicle.

The Challenger crew members are pictured in November 1985, about two months before the tragedy. Back row, from left: Ellison Onizuka, Sharon McAuliffe, Greg Jarvis and Judy Resnik. Front row, from left: Michael Smith, Dick Scobee and Ron McNair. (Credit: NASA)

What lessons were learned from the Challenger?

For every NASA mission, when something goes wrong or is unexpected, it gets documented as ‘lessons learned’, and you work to make sure it doesn't happen again. You either change operational requirements, or you change the design, or both.

After the Challenger accident, for example, NASA has had tighter weather criteria for launch. And they added heater strips around the O-ring joints on later flights as part of a redesign. So both operational and design changes were made.

It's a high-risk endeavor to start with, putting people into space. And I think it became very apparent at that point. The Challenger was the first in-flight fatal accident that had occurred in NASA's history. In the space domain, there are a lot of unknown unknowns, and those are the ones that can cause the biggest problem. But once they happen, they're not unknown anymore, and now you've got something you can design toward.

How do you view the legacy of the Challenger crew?

The Challenger incident was one of those generationally defining moments. It was a reminder that life is risky. If you're pushing the envelope, you accept the risks, and you do the best you can to mitigate those risks. But you can't ever make them go away. So the crew’s legacy was maybe a heightened awareness of the risk of space flight, but also the importance of continuing to go to space even when catastrophic events do occur.

Looking back 40 years later, what stands out the most about the Challenger?

The technical lessons learned made me start thinking more about risk analysis. It's one thing to design a vehicle that can meet all the needs and do the job, but once you get to that point in the design process, you now go back and start looking at it and saying, ‘What can go wrong? What happens if it goes wrong, and what can we do about it if it does go wrong?’

The human aspect, of course, goes without saying. These were some pretty outstanding individuals, and their lives were tragically cut short. But on the other hand, I don't think they would have stepped aside. Everyone understood that there was risk. The degree of risk might have been debatable, but anytime you're launching people into space—anytime you're walking across the street, for that matter—there's a degree of risk that you accept in your life to do what you want to do.

David Klaus

If you were speaking to young engineers now, what would you want them to understand?

When you're the one designing the rockets or the habitats or any of the infrastructure, pay attention to the details. Don't take shortcuts. Try to think beyond just ‘Here's an answer that's good enough.’

Consider risk analysis from the very beginning of the design. Think about all the things that can go wrong and try to design something that is what we call either fault tolerant or redundant. So, if something breaks, can the system continue working? Or do you have another way that you can provide that function in place of the thing that broke?

Think about what needs to be done and break it down into the functions that have to be accomplished to make that happen. Then brainstorm different ideas—not just one solution, but as many as you can come up with. And then work to find an optimal balance of risk and complexity from that process.Ìý