MIAMI • The United States is in a hurry to send people to Mars by the 2030s, but a key question remains for these deep space explorers.

What will they wear? An audit report out on Wednesday by the National Aeronautics and Space Administration's (Nasa) Office of the Inspector General found that the US space agency has spent lots of money and time on developing new spacesuits, but has little to show for it.

Despite spending nearly US$200 million (S$279 million) on Nasa's next-generation spacesuit technologies, the agency remains "years away from having a flight-ready spacesuit", said the report.

The white, bulky spacesuits worn mainly by US and European astronauts when they float outside the International Space Station (ISS) "were developed more than 40 years ago and have far outlasted their original 15-year design life".

Each suit has been refurbished over the years, with new features such as glove warmers. But the suits have suffered an increasing number of problems, such as water leaking inside the helmets.

Among other concerns raised by the report, just 11 of the original 18 life-support backpacks, known as extra-vehicular mobility units and which keep astronauts alive in the vacuum of space, still work.

Even beyond these technical mishaps, Nasa's current gear would simply not be suitable for deep space.

For example, next-generation spacesuits need to have better dust shields and more flexible hip sections so people can wear them while walking on the ground, whether inside a spaceship or on alien terrain.

Nasa has spent US$135.6 million on suits that could be worn on the Moon, but that programme, called Constellation, was cancelled during former United States president Barack Obama's administration.

More than US$51 million has also been spent on an Advanced Space Suit Project and US$12 million on an Orion Crew Survival System, for suits that could be worn in deep space. But these would need to be tested aboard the ISS prior to its scheduled retirement in 2024.

And Nasa is squeezed on time and money, having reduced funding for spacesuit development in favour of priorities such as an in-space habitat, the report said. "Given the development schedule, a significant risk exists that a next-generation spacesuit prototype will not be sufficiently mature in time to test it on the ISS prior to 2024."

AGENCE FRANCE-PRESSE