A small number of Naval Flight Surgeons—including two dual-designated Naval Aviators/Naval Flight Surgeons: CAPT David M. Brown, MC, USN (FS) and CAPT Joseph P. Kerwin, MC, USN (FS) -- have also qualified as astronauts. CAPT Kerwin flew in 1973 as Science Pilot aboard Skylab 1, becoming the first U.S. physician to fly in space. Two of these officers, CAPT Brown and CAPT Laurel Blair Salton Clark, MC, USN (FS) were both killed during the Space Shuttle Columbia disaster, mission STS-107, in 2003.