In what might embarrass less adventurous souls, astronaut Koichi Wakata is returning to Earth with the underwear he used during his 4 1/2-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 odor free.
The Japanese astronaut described his space underwear test Thursday 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 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."