Jeff Wisoff Reflects on Decades of National Service

At the end of April 2025, Jeff Wisoff will wrap up his 24-year career at Lawrence Livermore National Laboratory. In this question-and-answer interview, Wisoff reflects on his time as Principal Associate Director of NIF & Photon Science, the achievement of fusion ignition, and how his time at the NASA Astronaut Corps informed his approach to leadership.

Note: this interview has been condensed and edited for clarity.

Early Career and NASA Experience

When did you first know you wanted to be an astronaut? Was there a specific moment that solidified this dream?

I grew up in Norfolk, Virginia, during a time when I can remember men walking on the moon. It was an exciting era for space exploration that energized many people about science, engineering, and U.S. technical leadership. I didn’t initially set out to become an astronaut. I went to the University of Virginia for my undergraduate studies, and while I knew I wanted to pursue science, I wasn’t entirely sure what direction to take. I was interested in astronomy but wasn’t convinced it would provide a reliable living, so I majored in physics as a strategic move to keep my options open.

Was there a particular teacher or course that influenced your career path?

At UVA, I worked with Professor Dan Larson one summer, which sparked my interest in lasers. Later, at Stanford, I worked with Professor Robert Byer, who coincidentally would later lead the committee that certified the performance of NIF. It’s a small world—I actually met my future wife Tammy Jernigan outside Professor Byer’s door at Stanford, before we both became astronauts and well before NIF was built.

How did you get started at NASA?

After Stanford, I went to Rice University as a visiting faculty member and then as a tenure-track faculty member. NASA’s astronaut program had recently expanded to include scientists, not just military pilots. Sally Ride from Stanford had joined, and it opened opportunities for people with different backgrounds. I applied to NASA and got in on my second try, entering with the class of 1990.

I stayed at NASA until 2001, after my last flight in 2000. I had the chance to fly four times on the shuttle, visit both the Russian space station MIR and the International Space Station (ISS), and perform three spacewalks. My last mission involved working on the ISS assembly. Perhaps the most exciting experience was testing the astronaut jet pack, which was designed as a rescue device in case a spacewalker came untethered.

I feel obliged to take a detour to talk about the jet pack. How does it work?

The jet pack is built into your life support system and shoots gas in different directions for propulsion, allowing you to maneuver back to the space station over short distances. It has a deployable hand controller that attaches to your chest with a hook-and-loop fastener. One button nulls all your rates, so if you’re tumbling, it stabilizes you. Then you can use the hand controller to steer yourself.

The challenge is being efficient with the limited gas supply. We trained using a virtual reality helmet that simulated separating from the space station. On the actual flight, we performed jet pack test maneuvers after the ISS construction tasks were completed. I did my flight of the jet pack during the dark side of our Earth orbit. It was like being your own satellite while the earth spun below you. For safety, my partner was on the robot arm with a loose tether attached to me, just in case the system didn’t work as expected. It flew exactly as expected and is now a standard part of the spacewalking equipment on ISS.

How were you at handling heights?

Interestingly, some people do experience vertigo when they first exit for a spacewalk, feeling like they might fall. I never had that sensation, but there are other perceptual challenges in zero gravity. Your sense of what’s right side up can suddenly flip. I remember during my first spacewalk, the handrails on the shuttle initially looked incorrectly oriented to me, but after changing my focus, they appeared normal again. Astronauts train for the spacewalks in a giant pool with modified spacesuits that are neutrally buoyant to simulate floating. One advantage of actual spacewalking compared to the pool is that in space, you don’t have blood rushing to your head when you’re upside down, and you’re not fighting the viscosity of the water when moving large objects.

Time at LLNL and Fusion Ignition

You had a banner career at NASA. What brought you to Lawrence Livermore National Laboratory?

After nine shuttle flights between my wife Tammy and me (she had five, I had four), we decided it was time for something new. We both had Stanford connections and had great appreciation of the Bay Area, and we wanted to go somewhere with impactful missions similar to NASA. LLNL was a natural fit.

I was familiar with the Lab because they had built the Nova laser while I was studying lasers at Stanford. Like today, LLNL had the reputation as a world leader in laser research. Tammy, with a background in astrophysics, had connections with the physics directorate from serving on its External Review Committee. LLNL was building NIF at the time, and with my laser background and NASA experience, plus Tammy’s connections to the physics directorate, it was an ideal solution for both our careers. I joined LLNL in October 2001. At that time, Ed Moses, who was the NIF project manager, was interested in bringing in people from NASA and the Nuclear Navy who had experience with other large projects.

What was your first role at the Lab?

I initially worked with Mary Spaeth in systems engineering and was given responsibility for the “small optics” of NIF—the front end of the NIF laser system and the diagnostic packages. When I arrived, there were concerns about what NIF would cost, so we were working to simplify designs and scrub requirements for components like the preamplifier module, the master oscillator room, and the PABTS system, which magnifies and steers the beam from the preamplifier laser system into the main beam path. I later became the operations manager for the NIF and Photon Science Directorate, then the principal deputy, and eventually applied for and was selected for the Principal Associate Director position after Ed Moses retired.

A few years later, the Lab put the “I” in NIF. What did it take to achieve fusion ignition?

There were certainly highs and lows in the journey. A lot of sacrifice was made across the Lab to get NIF built, so finally getting to NIF’s dedication and certifying that the laser met requirements were major milestones. But then came a period when experimental results did not meet expectations, leading to budget questions and some lean times.

What proved critical was stepping back and breaking the problem into smaller pieces to better understand the physics issues and building stronger relationships both inside and outside the Laboratory. Over time, our capabilities increased. Improvements in our computational and diagnostic capabilities led to more 3D modeling and more real data providing insight as to where the problems were. These, coupled with better targets, optics, laser precision and more laser energy were crucial to ultimately achieving success.

Ignition was truly a Laboratory-wide achievement. Teamwork in the national interest is the superpower of the Laboratory. This is why LLNL exists—to do big, exciting, enabling, and transformative things for our country. I remember telling our team in our auditorium that the December 5^th experiment achieved ignition ... it was a thrill like seeing the large rocket finally lift off the pad; a testament to the incredible things humans can do when they work together with dedication and common purpose.

What surprised you the most about leading NIF?

What amazes me is how NIF has constantly evolved. Often when you build something, it can easily become frozen in time. But with NIF, we keep adding capabilities and making it more capable and more unique in the world. The laser is well over a decade old, yet we’re increasing its energy rather than reducing it. We plan through a proposed Enhanced Yield Capability (EYC) project to take the laser from the current 2.2 MJ energy per shot to around 2.6 MJ per shot. That’s a testament to how Livermore continuously pushes boundaries to achieve big goals.

What’s a bigger deal: going on a spacewalk or leading NIF?

People often ask me if NIF or the International Space Station (ISS) was harder to build. I tell them that NIF is more sophisticated and precise in all its engineering than ISS, but the commute to the ISS worksite was much harder! In all seriousness, I hope one of the things I brought to the directorate was the same sense of team spirit and “we’re-all-in-it-together" that I experienced at NASA. Spending a lot of our life at work doing missions in the national interest should create a special bond; you can feel it here.

What role did collaboration play in achieving ignition?

Collaboration was essential. This included building collaborations both inside and outside the Lab. Ignition is hard, so we needed as many smart people as possible lending their ideas to overcome obstacles. Some of these people were in areas where lasers can complement NIF, such as applications for Department of Defense missions and scientific facilities. These projects created support for additional laser expertise that could help with NIF when needed.

The NIF&PS directorate functions in a “swarming mode” on problems, quickly moving the best people across projects into place to resolve issues. Our relatively narrow focus on lasers, optics, and HED experimental science means everyone understands the projects and feels vested in their success. It creates a certain esprit de corps that leads to the "all-in-it-together" attitude to solving problems.

What does achieving ignition mean for the country and world?

First and foremost, ignition sends a clear signal to our allies and adversaries that the United States is at the absolute bleeding edge of HED science and stockpile stewardship. This helps place doubt in the minds of potential adversaries about their ability to act aggressively without paying a price, which is the basis for deterrence.

Ignition has also opened up tremendous interest in inertial fusion energy, which the whole Laboratory, not to mention a burgeoning public-private movement, can now contribute to. We’ve described ignition on NIF as being like the Wright Brothers’ first flight. If you stood at that moment watching their rickety plane, you couldn’t have imagined something like the SR-71 Blackbird flying just decades later.

Similarly, while we have visions of what a fusion power plant might look like over the next 20 years, the version that exists 50 years from now may look very different. Keeping the analogy to airplanes, we’re in the “barnstorming era,” where various approaches to commercial fusion are being proposed. Some will succeed and attract more financial backing, while others will fade away as part of a natural selection process.

Is fusion energy inevitable?

It’s a matter of when, not if—assuming we don’t get distracted by other challenges. Eventually, energy security will become important enough that significant resources will flow into fusion development. The jury is still out on which approach to fusion energy will be most commercially viable. My view is that when you don’t know which path will succeed, you should advance all promising approaches to overcome technical barriers and see how things develop.

Leadership and Legacy

Looking back on your career, what are you most proud of?

Technology is always fascinating, but it’s the people who are truly amazing. We couldn’t achieve what we have without the dedicated teams at the Lab. The real advantage LLNL has is its mission—people want to contribute to national security and see it as important enough to dedicate a significant part of their lives to. Being part of nurturing that legacy of unsurpassed scientific and operational excellence at the Laboratory is the most satisfying to me because it means we are not done yet. There are many great discoveries to come.

What advice do you have for the next generation of leadership at the Lab?

Maintaining the collaborative approach is crucial. The incredible dedication and teamwork required to execute NIF shots—particularly ignition shots—is remarkable. There are always problems but with the right esprit de corps, the team will swarm and do what is necessary to succeed. Establishing that spirit in the workforce comes from leadership removing barriers, establishing open communication, and trusting the team to exercise good judgment in their everyday work. Building on a foundation of technical and operational excellence while nurturing the collaborative culture will be key for future leaders.

Looking Ahead

How do you see the public perception of fusion evolving?

I believe public interest and support will grow as fusion demonstrates increasingly practical results. The ignition breakthrough captivated people’s imagination, similar to how early aviation achievements did. As technical challenges are overcome and fusion moves closer to commercial viability, I expect both public and private investment to accelerate.

What message would you like to share with young people considering careers in STEM?

The work we do at national laboratories demonstrates what’s possible when scientific knowledge is applied to important challenges. Whether in space exploration or fusion research, these fields offer the opportunity to push boundaries and contribute to society in meaningful ways. The excitement of discovery and the satisfaction of solving complex problems make STEM careers incredibly rewarding. My advice is: jump in!

Thanks for taking the time, and best wishes for the next chapter.

Thanks, and to all my colleagues at the Lab, I wish you great success in the future.

More Information:

“NIF’s Jeff Wisoff and Jean-Michel Di Nicola Elected Optica Fellows,” NIF & Photon Science News, November 14, 2023

“Astronauts Launch ‘Dream Big’ Mural with Recipes for Success,” NIF & Photon Science News, November 16, 2022

“Apollo 11 Inspired LLNL’s Wisoff, Jernigan,” NIF & Photon Science News, July 24, 2019

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