Ethan Stiefel’s new work for the Washington Ballet, “Frontier,” is about astronauts and space travel. The dancers wear spacesuits. They’re sleek, tailored, zip-up affairs, vaguely authentic looking, as though NASA and New York’s Seventh Avenue met and made a onesie.

In fact, that is what happened. Stiefel calls it “a wild, serendipitous coming-together” that led to his collaboration with Ted Southern, owner of a company that creates spacesuits and safety garments, and Southern’s wife, fashion designer Flora Gill, who founded the womenswear label Ohne Titel and once designed for Karl Lagerfeld. 

“Frontier” will have its world premiere May 25, with performances continuing through May 27 at the Kennedy Center Opera House. It tells the story of a group of ASCANS — the NASA acronym for astronaut candidates — and flight technicians preparing for a mission, and the stage effects include a rocket launch and travel to a distant planet.

Just 25 minutes long, the ballet is a big event for everyone involved, but especially for Stiefel, the retired American Ballet Theatre star who is unveiling his first major commission as a choreographer, and for Washington Ballet Artistic Director Julie Kent, who asked Stiefel, her friend and former dance partner, to tie his ballet to the Kennedy Center’s John F. Kennedy centennial celebration. That’s where the space theme came from, reflecting the former president’s expansion of the space program. 

“Frontier” is Kent’s first commission as director, and it is the much-anticipated centerpiece of her inaugural season’s grand finale. The new ballet shares the program with two established 20th-century masterpieces — the heartbreaking “Jardin aux Lilas” (“Lilac Garden”), by Antony Tudor, a tale of clandestine love and duty, and Frederick Ashton’s effervescent “The Dream,” a distillation of Shakespeare’s “A Midsummer Night’s Dream.” The three ballets will be accompanied by a live orchestra and performed on the Kennedy Center’s largest stage, on which the Washington Ballet last appeared in 1988.

Stiefel’s ballet follows the path of a female ASCAN who, like Stiefel and Kent in their new roles, is finding her footing in several ways. Gill and Southern fit right in with this crew of enthusiastic newcomers — they’re first-time ballet-costume designers, although Southern got his start in design by making the giant angel wings for the models in a Victoria’s Secret fashion show, and has crafted costumes for movies (“Spider-Man”) and Cirque du Soleil. There’s not a lot of demand for an aerospace/ready-to-wear duo, so Southern and Gill had never teamed up in their professional lives.

“We were so excited when we got this project,” Gill said in a telephone interview. “This was the perfect project for us to work together on for the first time.” 

With his company, Final Frontier Design, the 39-year-old Southern was used to pouring years of research into prototyping gloves for NASA, for example, while Gill, 36, had been churning out collections for Ohne Titel (German for “untitled”) with a partner, designing dresses and pantsuits with a postmodern edge. Gill folded her company a year ago, however, so Stiefel’s call to the couple’s Brooklyn home, at the urging of a mutual acquaintance, came at the perfect time.

“I had this image of a warrior-athlete, preparing for battle,” Stiefel says. “So we’ll see the astronaut go from human to a more superhero look. And what many times we hide — the costume change — in this case, it’s part of the choreography.”

There’s a scene in the ballet devoted to donning and doffing the spacesuit onstage, and that required separate rehearsals for all the Velcro and zipping and unzipping. Real ASCANS would have done this “a thousand times,” Stiefel tells his dancers on a recent afternoon at the Washington Ballet’s Wisconsin Avenue NW studios. “So that’s the sensibility we’re going for.”

Among the costume accessories neatly arrayed on the floor — gloves, shin guards, arm cuffs, harness, backpack — NASA’s love of Velcro is evident everywhere. There are also zips and snaps, a mesh cap and a helmet. So many opportunities for a wardrobe malfunction . . . but that’s why this rehearsal has been called.

“Okay, you walk — one, two, three, four, five, six, seven — and kneel on eight,” Stiefel tells Sarah Steele, a willowy, dark-eyed 22-year-old. She was recently hired as an apprentice, and Stiefel plucked her from that bottom rank to star in his ballet. Her courage at the outset of rehearsals attracted him. She possesses, he says, “the essence of a strong, brave artist.”

“You have a full eight counts to zip,” he continues. “Then you’ll get lifted. Turn on four, arms on five. Four counts for the gloves. . . . Lift on five; six, you get into the backpack.”

Steele and the dancer-crew members who are helping her dress eye him intently, tallying up the counts in their heads. The first few run-throughs are rocky — Steele’s zipper snags on the waistband of her tights, the gloves don’t cooperate. The helmet strap must be snapped — oh, where is it, where’s that dang other end? — and, meanwhile, the cyber beats in the commissioned music are racing on. Ah, at last, success! Well, the helmet’s a little askew. But Steele stands triumphant, ready for takeoff, fists clenched at her sides in the ready position.

“This is going to work,” Stiefel assures his dancers. “This will be absolutely no problem. We have two weeks to work on it.”

With spacesuits, it’s easy to get into the sci-fi aesthetic or wander too far in the David Bowie direction. At the get-go, Stiefel told the designers that he wasn’t after glitter gods and that they should avoid design details on the shoulders and hips, please — no dancer wants to draw attention there.

The flight costume resembles what’s called a mechanical counter-pressure spacesuit, an experimental concept that uses formfitting materials rather than the “big balloon” of the conventional suit. It’s more of a suggestion than a replica, because the donning/doffing scene “dictated a lot of the design choices,” Southern says. He included some rigid motocross armor and fasteners for football equipment, while Gill made sure everything looked good on the body and was visible from an opera-house-size distance.

Having enjoyed this first collaborative project, the couple are now diving deeper into tech-inspired fashions. They’re planning to launch a clothing line called Space Rated, “to take some of the technological advances done for spacesuits and bring them into the clothing sphere, and make scientific knowledge as cool as streetwear,” Gill says. She likens it to an aerospace version of the cult skater label Supreme.

“It’ll be inspired by the legitimate scientific research that Ted is working on,” she says. No word yet on what the line will include, but who knows? “Frontier’s” ballerina-ASCANs may help put slim-fitting, futuristic jumpsuits into the mix.