In what might embarrass less adventurous souls, astronaut Koichi Wakata is returning to Earth with the underwear he used during his 4-month space station stay so scientists can check them out.
Warning to researchers: He kept them on for a month at a stretch.
They're experimental high-tech undies, designed in Japan to be odour free.
The Japanese astronaut described his space underwear test today as shuttle Endeavour and its crew aimed for a touchdown the next morning. The astronauts released some mini satellites, their final job before Friday's re-entry, and said it was time to come home after more than two weeks aloft.
"I haven't talked about this underwear to my crew members," Wakata said, 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."
The underwear, called J-Wear, is a new type of anti-bacterial, water-absorbent, odour-eliminating clothing designed for space missions. The line includes shirts, pants and socks as well. Wakata tested all of them during his mission; he had four pairs of the silver-coated underwear, a cross between briefs and boxers.
"We'll see the results after landing," Wakata said.
J-Wear is billed as being antistatic and flame retardant, which is especially important for spaceship wear.