After circling Earth 2,208 times and enduring numerous near misses with speeding space junk, Koichi Wakata could be described as the kind of person who flies by the seat of his pants. But the Japanese astronaut proved during his 138 days in space that he is not the kind of person to kick up a stink about things.

As the space shuttle Endeavour prepared to return to Earth yesterday, bringing Mr Wakata home from the International Space Station, where he has been since March, he revealed that he had been wearing the same pair of prototype pants for a month, all in the name of science.

Designed to resist the rigours of lengthy space travel, the anti-static, flame-resistant, odour-eating, bacteria-killing, water-absorbent smalls have been put through their paces as part of a project aimed at ensuring that future space travellers will need only minimal space in their suitcases.

“We’re going to go beyond the Moon some day, and little things like this will seem like really, really big things when you’re far away from Mother Earth,” Mike Suffredini, manager of Nasa’s space station programme, said.

If Mr Wakata’s colleagues noticed that he had been skimping on his laundry, they were polite enough not to let on — and he refrained from bringing it up in conversation. “I haven’t talked about this underwear to my crew members,” he said during a pre-landing press briefing.

He added: “I wore it for about a month and my station crew members never complained, so I think the experiment went fine.”

Mr Wakata, 46, ate a number of curries in space, along with Japanese-style dishes such as salmon rice balls. He said that upon his return to Earth he looked forward to eating fresh sushi and cold noodles and taking a hot shower.

Mr Wakata’s special clothing range was designed by the Japanese space agency, Jaxa. It also includes socks, T-shirts, trousers and leggings, all made of cotton and polyester with a futuristic-looking silver coating.

The clothing made its debut in orbit last year when Takao Doi, another Japanese astronaut, tested it out for 16 days. But scientists wanted the product put through more rigorous testing to assess its durability.

Other astronauts on the space station usually pack their dirty laundry into unmanned Russian cargo ships, along with their rubbish, then send the craft back towards Earth. They burn up en route.

This was not an option for Mr Wakata. His clothing has been placed in special bags ready to be taken to a laboratory, where experts will examine how well it held up to the challenge.

Eager to prove that he was not just a space clothes horse, Mr Wakata talked about the success of the other tasks he performed while in orbit.

One was the testing of a “magic carpet” — a white sheet that acts like a surfboard, allowing the astronaut to move through the cabin standing upright. “I flew on this magic carpet by using adhesive tape so that the soles of my feet stayed on it,” he said.

The test was among 16 unorthodox experiments suggested by Japanese schoolchildren to see how various items performed in zero gravity. Others included how to fold and store laundry when the garments kept floating away, and how to administer eyedrops in space.

Endeavour touched down at the Kennedy Space Centre in Florida at 10.48am (3.38pm BST) yesterday.

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