Moonwalking astronauts will have sleeker, more flexible spacesuits that come in different sizes when they step onto the lunar surface later this decade.

Exactly what that looks like remained under wraps. The company designing the next-generation spacesuits, Axiom Space, said Wednesday that it plans to have new versions for training purposes for NASA later this summer.

The moonsuits will be white like they were during NASA's Apollo program more than a half-century ago, according to the company. That's so they can reflect heat and keep future moonwalkers cool.

The suits will provide greater flexibility and more protection from the moon's harsh environment, and will come in a wider range of sizes, according to the Houston-based company.

NASA awarded Axiom Space a $228.5 million contract to provide the outfits for the first moon landing in more than 50 years. The space agency is targeting late 2025 at the earliest to land two astronauts on the moon's south pole.

At Wednesday's event in Houston, Axiom Space chief engineer Jim Stein modeled a dark spacesuit, doing squats and twisting at the waist to demonstrate its flexibility. The company said the final version will be different, including the color.

The suit features a backpack Axios Space described as a "portable life support system."

"Inside of this box are all the parts and the components to keep you alive," said Russell Ralston, deputy program manager for extravehicular activity at Axiom Space.

"You can think of it as like a very fancy scuba tank and air conditioner kind of combined into one."

The suit is designed to be worn for up to eight hours at a time.

Vanessa Wyche, the Johnson Space Center director, said the new suit has "more functionality, more performance, more capability" than the bulky version worn by Apollo astronauts.

"We have not had a new suit since the suits that we designed for the space shuttle and those suits are currently in use on the space station," Wyche said. "So for 40 years we've been using the same suit based on that technology."

While Axiom Space described the newly-unveiled spacesuit as "revolutionary," one thing has not changed since the days of Apollo.

"We're still using diapers in the spacesuits," Ralston said. "They're just honestly a very effective solution."

"Sometimes simplicity is best and this is one of those cases."