Plainfield — Astronaut Barry “Butch” Wilmore, the first Space Shuttle pilot to walk in space, recalled Thursday that the battery that powered his backpack never stopped emitting “a high-pitched electric sound.”

And he’s ever so grateful.

“You might think that would get irritating after six hours,” Wilmore told a gathering at BST Systems, the specialty-battery maker. “No, it just meant it was working. … I love you guys.”

Wilmore, soon to retire after a 30-year career in the Navy, regaled BST employees, executives and invited guests with stories about his experiences as an astronaut, which have included shuttle flights to the space station in 2009 and 2014, the latter aboard a Soyuz spacecraft. Wilmore commanded the station from November 2014 to March 12, 2015, when it touched down in Dzhezkazgan, Kazakhstan.

He has logged 178 days in space and 25 hours, 36 minutes in four spacewalks.

“I really like the fact that this worked,” he said, handling a BST battery.

BST’s batteries have been working since the company’s founding in 1983, powering manned and unmanned forays in space and undersea (via Navy SEAL submersibles, not submarines). They played a key role in the Space Shuttle Atlantis launchings from 1998 to 2011, and the company has adapted a design for the Space Launch System that’s expected to propel the Orion spacecraft on “deep space” missions, including to Mars.

Kendall Junen, an official from NASA's Marshall Space Flight Center in Huntsville, Ala., said more than 1,100 contractors in 43 states are working on the project, including dozens in Connecticut.

U.S. Sen. Richard Blumenthal, D-Conn., and U.S. Rep. Joe Courtney, D-2nd District, also were on hand to pay tribute to BST and its employees.

Tom Terjesen, BST’s director of manufacturing and son of one of the company’s founders, said Thursday’s event was designed in part to remind employees of the significance of their work.

“It’s important to show them how impactful it is,” he said. “A lot of it’s assembly work and they don’t get to see the outcome. It’s an art form, though — a lot of hands on, not much automation.”

BST employs about 50 people.

Zoe Adamedes, a company spokeswoman, got a chance to observe the fruits of BST labors in July when she attended the test launching of a rocket powered by the company's batteries.

“When that rocket lifted off, the ground shook for minutes,” she said. “You see the flames, then seconds later hear the roar and feel the vibration. It was so thrilling. It made me think about what we do here.”

b.hallenbeck@theday.com