by Andrew Faught

As the space probe hurtled toward Pluto in what would give the world its clearest-ever glimpse of the mysterious dwarf planet, the unthinkable became reality.
 
“This is my life’s work, and then 10 days before coming to fruition, I had my worst nightmare,” says New Horizons mission systems engineer Chris Hersman, Eng ’88. “It was 48 hours of terror.”

The date was July 4, 2015, not quite a decade after the probe, which is the size and weight of a grand piano, was flung into the cosmos to study and photograph one of the solar system’s farthest outposts. Suddenly, and without explanation, Hersman and his team lost communication with the craft.

Nervous moments turned into a two-day race to find the cause of the blackout and avoid missing the start of the nine-day “encounter command sequence,” in which New Horizons would snap photos of Pluto and collect atmospheric data. In the end, Hersman and his colleagues at mission headquarters, Johns Hopkins University’s renowned Applied Physics Laboratory, regained transmissions — with a scant 12 hours to spare.

The fix was simple, although the problem, or anomaly, as engineers are wont to say, wasn’t anything for which Hersman and his colleagues had planned. The craft’s computer had become overloaded when its earthbound operators sent it Pluto flyby instructions at the same time the computer was compressing data to make room for new information.

“It was essentially a software conflict,” says Hersman, whose job is to ensure that all technical aspects of the mission run smoothly. “They were operations that shouldn’t have taken place at the same time.”

The episode played to his strengths, according to those who know him. Not only does Hersman embody a natural equanimity, but he also possesses a knack for rooting out the source of trouble, notes Alice Bowman, the mission’s operations manager.

“Chris has the ability to focus on the minute details of what’s going on,” Bowman says. “When there’s a problem on the spacecraft, he leaves no stone unturned. Which is a huge benefit, because many times what you see on the surface is not necessarily the root cause of the problem. And he’s very cool under pressure.”

For Hersman, the Pluto mission is the culmination of a lifetime of tinkering and scientific inquiry. He was on the team that proposed the mission in 2001, part of NASA’s New Frontiers program to develop missions to study Jupiter and Venus, in addition to Pluto.

Watching the Apollo moon missions as a kid wasn’t the only factor that fired Hersman’s imagination and propelled him into a career as a space-age electrical engineer. Growing up in suburban Greenhills, just north of Cincinnati, he began disassembling unusable televisions and radios as a teenager. Trying to figure out how things worked became a way of life. He even wowed UC friends with his quizzical creations.

Hersman lived in Calhoun Hall with childhood pal and roommate Sean Keith, Eng ’88, a chemical engineering major who now is an executive with GE Aviation. The pair built a loft on which they could perch their beds to create more floor space. But there was one problem. Neither man could reach the light switch once they were in bed.

“It’s a source of pride for me to know Chris and what he’s accomplished.”

It was at UC, where Hersman got his undergraduate degree in electrical engineering, that he would learn the maxim that continues to inform his work: Test as you fly, and fly as you test. In simplest terms, the adage, subscribed to widely by NASA engineers, means ground tests and simulations should accurately reflect the planned mission.

Wavering from a plan can have disastrous effects, as Hersman can attest. Luckily for him, his early misfortunes came with much lower stakes: as a participant in the college’s egg drop contest. From a balcony at Rhodes Hall, students attempted to lower a raw egg to a target 20 feet below. They could employ whatever methods they saw fit to keep the egg intact.

Using fishing line, pulleys and an improvised egg “hammock,” Hersman figured his own plan was foolproof. Until the day of the competition, when he decided to use thicker fishing line. He assumed the extra tensile strength would improve his chances for success.

“My friend who was working with me asked, ‘Are you sure we should change anything?’ I said ‘Yes, I know what I’m doing,’” Hersman recalls with a now-knowing laugh. “I rewired the larger line and, sure enough, when we went to do it, the line was a little bit too big and it jammed in the system of pulleys.”

The effort ended with a splat. But it taught Hersman a critical lesson.

“Ever since then, I realized you don’t change something after you test it,” the engineer says. “Even though it was a small consequence at the time, it was very important to test as you fly.”