Carol Mullins knows the secrets of St. Mark’s Church in-the-Bowery. She knows that it’s strangely colder by the crypt of Peter Stuyvesant, who had the first chapel built on the site, now in the East Village, in 1660. She knows which architectural features predate the fire that destroyed much of the late-18th-century building in 1978. She knows the location of the hidden trapdoor that leads to the rafters of the arch above the nave.

“It’s a wonderland of wood,” she said recently. “It looks like an upturned boat in there.”

Mullins, 85, knows all this because just before that fire, she started designing lighting for Danspace Project, which has been presenting performances in the church since 1974. In 1982, she became the resident lighting designer, a position she still holds.

At Danspace’s 50th anniversary gala on Tuesday, Mullins will be among the honorees. It’s an acknowledgment of one of the under-sung troopers essential to dance in New York, especially the underfunded, boundary-pushing “downtown” kind that Danspace has fostered.

When people ask her why she has stayed there so long, she replies that she’s still learning, “and there’s a new set of problems every couple weeks.”

After so many years, St. Mark’s Church is a palimpsest of memories for Mullins. An early one involves the choreographer Ishmael Houston-Jones, whose work “Relatives” Mullins lit in 1982. For the end of the dance, during which Houston-Jones jumped as the lights faded, he told her to keep the lights up “as long as you like it.”

“I thought it looked fabulous,” Mullins recalled. “So he’s dying out there, jumping and jumping. Since then, he occasionally jokes about my sense of timing.”

Mullins is well aware of the sanctuary’s limitations as a performance space. There are no wings and no lighting grid, so lights have to be hung along the balcony and the columns, meaning no directly overhead angles. And because the church is still used as a church, set pieces and lighting equipment on the floor have to be moved out between shows. (And, in reverse, so does most of the religious iconography.)

But more than limitations, Mullins knows the possibilities and advantages. She loves the height — “the spires pointing up to God and all of that,” she said. And while the white walls make light bounce, they also serve as a blank canvas.

Another advantage is Mullins herself. She sees her job as a service to others. And while she has her proclivities — she likes color, dislikes dimness — she said she “resists the temptation to impose.” She tries to figure out what artists want to accomplish and how to do it.

The young choreographer Andros Zins-Browne, who worked with Mullins in February, said he was surprised by her “astoundingly contemporary sensibility” and how attentive and open she was.

“She was never precious about her ideas, which left me a lot of space not to be precious about mine,” he said. “She immediately knew how to use the available resources to do what I was looking for. And she also knew how to push back,” making suggestions “that just looked better.”

Vicky Shick, a choreographer who has worked with Mullins many times since 1996, called her designs “a subtle dazzle as opposed to a big show-off.”

“She takes delight in your work and can look at it and pick up things you might not notice,” Shick said. Even under pressure, Mullins “acts like we have all the time in the world,” Shick added.

Shick spoke of Mullins’s ability, while on tour, to be a logistics whiz and to strike up a rapport with different crews. “She organized us,” Shick said, “but she’s also in the lobby late at night, giggling and telling stories. I think she had kind of a wild life.”

That life started in Lorton, Virginia. “It was the home of three prisons,” Mullins said. “The motto of the town was ‘Not Just a Place to Do Time.’”

She got out of there as soon as she could, studying chemistry at George Washington University but not quite graduating. She got a job with a technical publisher that relocated to New York from Alabama. But she received a grant to do volunteer work in Bangkok and it was there, in 1970, that she received disturbing letters from her best friend back in New York.

“She was saying things like ‘I bounced on a board for five hours in an alley and it was the most meaningful experience of my life,’” Mullins said. “I thought she was in some cult and I had to get her out.”

Instead, Mullins returned to the city and joined that cult, or at least a cultlike artistic collective: the Byrd Hoffman School of Byrds, run by Robert Wilson. Mullins started performing in Wilson’s scrappy avant-garde shows, which could last many, many hours. (So did her husband, the experimental playwright Jim Neu.)

The choreographer Douglas Dunn, who has collaborated with Mullins on more than a dozen Danspace shows, remembered seeing her in a Wilson production, silently reading to herself onstage alongside the dance critic Edwin Denby. “They both had gleaming white hair,” Dunn said. “It was a profound image.”

One day in Spoleto, Italy, Wilson asked Mullins to take over the collective’s lighting design. “I knew nothing about lighting,” she said, “but Bob had an intuitive feel for what people would be good at.” He was right, and he helped, not with technique but with vision: “Bob taught me how to see.”

In Europe, the members of Wilson’s troupe were treated like stars. When one of their productions moved to Broadway, Mullins said, the experience was a fiasco, making her realize that Broadway wasn’t for her.

In any case, Wilson’s next production was the Philip Glass opera “Einstein on the Beach,” Wilson took over the lighting, and Mullins couldn’t sing. She became the lighting designer for Wilson-adjacent artists, particularly the choreographer Andy de Groat. In 1982, de Groat relocated to Europe, putting Mullins out of a job. Cynthia Hedstrom, the director of Danspace at that time, called up to offer her one that lasted. (Since 1998, she has shared the Danspace position with Kathy Kaufmann.)

One of Mullins’s favorite memories of the years that followed is about the star experimental choreographer Steve Paxton. At the end of a show, he was given a bouquet. He picked out a rose and threw it up to Mullins, who leaned out from her perch on the balcony to catch it.

“I had this immense feeling of satisfaction,” she said. “Nobody throws flowers at me.” At this year’s gala, at least metaphorically, she’ll get her own bouquet.