STS103-E-5243 (22 December 1999) --- Astronaut John M. Grunsfeld, mission specialist, on Discovery's mid deck wearing the thermal undergarment which complements the extravehicular mobility unit (EMU) space suit. Grunsfeld joined astronaut Steven L. Smith for the first scheduled space walk on this the third NASA visit to HST. This photo was taken with an electronic still camera (ESC).