Astronaut Kathryn Thornton during installation of COSTAR on HST

STS061-98-0AR (8 Dec 1993) --- Earth is partially illuminated but the Hubble Space Telescope (HST) and the Space Shuttle Endeavour are still mostly in darkness, in this 70mm frame photographed during the fourth of five space walks. Astronaut Kathryn C. Thornton, barely visible above left center in the frame, works to install the Corrective Optics Space Telescope Axial Replacement (COSTAR).