Surrounded by brilliant white, we grin goofily at each other as we sit stiff-backed on opposite sides of a stuffy airplane cargo bay. It could be a weird scene from 2001: A Space Odyssey, where they might stash astronauts who’d gone berserk in space. Clean, white floor cushioned with inch-thick foam. Padded walls and ceiling swathed in white vinyl. Clumps of strange-looking apparatus bolted to the floor. But this is no movie scene. It’s NASA’s sleek KC-135, a modified Air Force gas tanker dubbed the “weightless wonder,” flying out from Houston over the Gulf of Mexico on a hot July morning at more than 400 mph.