Special underwear tested by Japanese astronaut Koichi Wakata in the International Space Station has returned after the one month mission.

The Japanese underwear, called J-Wear, is a new type of anti-bacterial clothing designed for space travel and made by top textile maker Toray.

Each item of underwear was finished with a special nanotech fabric developed by Toray that can repel static, wick away water, kill bacteria, neutralise odours, and "prevent fouling, or permanent odour infusion."

"I haven't talked about this underwear to my crew members," Wakata said in an interview with The Associated Press, drawing a big laugh from his six shuttle colleagues.

"But I wore them for about a month, and my station crew members never complained for about a month, so I think the experiment went fine."

By Michael Fitzpatrick.