Interview with Todd Barber: The Rocket Scientist Who Keeps Voyager Flying

From a Kansas Backyard to the Edge of Interstellar Space

When Todd Barber looked through a small backyard telescope as a kid in Kansas, he never imagined that decades later he’d be steering two of humanity’s farthest spacecraft — Voyager 1 and 2, now traveling beyond the edge of the Solar System.

Today, Barber serves as a Senior Propulsion Engineer at NASA’s Jet Propulsion Laboratory (JPL), with over 35 years of experience across missions like Galileo, Cassini, Mars rovers, and Voyager itself. A lifelong space enthusiast and MIT-trained propulsion specialist, he’s one of the quiet figures behind the loudest moments in NASA history — from Saturn orbit insertions to the “seven minutes of terror” that defined Mars rover landings.

“I’m one of about a dozen people still working on Voyager,” he said. “Out of eight billion on Earth, that’s pretty humbling.”

Discovering a Lifelong Passion for Space

Barber’s love of science began early. “By age five, I already knew I was a STEM kid — and this was before STEM was even a word,” he laughed.

Encouraged by his father, who “could fix anything,” he spent childhood days disassembling gadgets, running home science experiments, and launching model rockets. A telescope gifted to his family opened an even bigger universe. “Seeing Jupiter’s moons and Saturn’s rings through that lens changed me,” he said.

Then came Voyager’s flybys of Jupiter and Saturn in the late 1970s. “I remember reading National Geographic’s spread of Voyager images at my grandparents’ house,” he recalled. “Those pictures — the storms, the moons, the magnetic fields — hooked me for life.”

That fascination eventually led him to study Aerospace Engineering at MIT, where he found both his “tribe” and his calling. “In high school, being a nerd wasn’t cool,” he said. “But at MIT, I was surrounded by people just like me.”

Finding His Tribe at MIT

Barber earned both his bachelor’s and master’s degrees at MIT, specializing in propulsion. “I loved the chemistry of it,” he said. “All those childhood explosions and model rockets finally made sense.”

He fondly recalls MIT’s infamous “Unified Engineering” course — a grueling, year-long gauntlet integrating fluid mechanics, structures, dynamics, and propulsion. “They call it drinking from a firehose, and they’re not kidding,” he said. “At the time, I wondered if anything was sinking in — but years later at JPL, I realized I was using it every day.”

Barber later became a teaching assistant for the same class. “By the third time through, I finally understood it,” he joked. “It was like unlocking the matrix.”

Launching a Career at JPL

After graduation, Barber landed his dream job at NASA’s Jet Propulsion Laboratory in 1990. “My first assignment was mission operations for the Galileo spacecraft on its way to Jupiter,” he said. “I couldn’t believe it — I was working on a mission to the same planet that inspired me as a kid.”

JPL had a tradition of training new hires by putting them on flight operations for existing missions before assigning them to new designs. “It’s the best way to learn how to ‘speak JPL,’” Barber said.

But a hiring freeze soon followed, and his “six-month rotation” in operations turned into a 35-year career. “Most people want to move on to design work,” he said. “Not me. I absolutely adore flying these spacecraft.”

Over the years, Barber’s name became synonymous with propulsion operations. “If a new mission has a propulsion issue,” he said, “my phone usually rings.”

Keeping the Cassini Spacecraft Alive

Barber spent 21 years on the Cassini mission to Saturn — what he calls “the middle years of my career.” Despite its complexity, he said Cassini was “the smoothest mission I’ve ever worked on.”

That doesn’t mean it was without challenges. “Two weeks after launch, we discovered a leaking regulator in the propulsion system,” he said. “We had to close valves and monitor pressures carefully to prevent catastrophic overpressurization. It wasn’t fun — but it worked.”

At the other end of Cassini’s life came a more existential problem: running out of propellant.

“There’s no gas gauge in space,” Barber explained. “So I became the human gas gauge.”

Using complex thermal and pressure models — along with creative methods like heating the propellant tanks to observe how quickly they warmed and cooled — Barber estimated fuel levels with remarkable precision.

“At the end of Cassini, I had 1% propellant left, plus or minus 2%,” he said with a laugh. “So I was either brilliant or out of gas.”

Landing on Mars — the “Seven Minutes of Terror”

In addition to Saturn, Barber has worked on all three generations of Mars rovers — Spirit, Opportunity, Curiosity, and Perseverance.

While the early missions used airbags to bounce to safety, the later rovers employed the now-famous sky crane technique, lowering the rover onto the Martian surface via rockets.

“The 7 minutes of terror — that’s real,” Barber said. “But the funny part is, there’s nothing we can do during it. Mars is so far away that by the time we see the spacecraft enter the atmosphere, it’s already landed — or crashed.”

For the engineers, that delay creates both relief and suspense. “It’s Schrodinger’s Cat in real life,” he said. “We’re waiting to see if it’s alive or dead.”

When the touchdown confirmation finally comes, though, it’s pure joy. “We jump around, we cry, and within minutes we get the first photos from a place no human has ever seen up close. There’s nothing like it.”

Lessons from Mistakes

Barber openly discussed one of his early errors — a mass calculation mistake during Galileo mission planning.

“I forgot to remove the mass of the entry probe,” he said. “Two months of calculations — all wrong. I was mortified.”

But the experience taught him an enduring lesson about accountability. “I learned to always own your mistakes,” he said. “Hiding them only makes things worse. If you’re honest and fix it fast, your team will respect you more.”

Propulsion Mysteries and Public Misconceptions

According to Barber, one of the biggest misconceptions about propulsion is how uncertain it can be. “People think we know exactly how much fuel is left — we don’t,” he said.

In zero gravity, propellant doesn’t settle, so there’s no simple gauge. “We use models, equations of state, even heat transfer methods to infer the amount,” he said. “Each has errors — but together, they get us close enough to make history.”

Barber also described how even small human errors can be mission-ending. “We send thousands of commands to these spacecraft,” he said. “One wrong line can destroy a mission. That’s why uplink review — as boring as it is — might be the most important part of my job.”

Advice for the Next Generation

When asked what advice he’d give to aspiring aerospace engineers, Barber emphasized teamwork, communication, and integrity.

“In school, it’s about individual grades and rankings,” he said. “But in this business, it’s all about collaboration. No one builds a spacecraft alone.”

He also encouraged young engineers to write well. “Good English matters,” he said. “You’ll need to explain complex problems clearly — to managers, peers, even the public. Writing is an underrated engineering skill.”

Above all, he said, stay curious and humble. “Even at 60, I’m learning new tricks,” he added. “I just became the Attitude Control Engineer for Voyager, even though I haven’t taken a controls class in 38 years. I’m nervous — but excited. That’s the beauty of this career. You never stop learning.”

Full Circle

From gazing at Voyager pictures as a kid to flying the real spacecraft decades later, Todd Barber’s story is a full-circle journey of passion, perseverance, and purpose.

“The boy looking at those National Geographic photos got everything he dreamed of — and more,” he said. “Thanks to hard work, good mentors, and the thrill of chasing the stars.”