D arl Thomas mopped the streams of perspiration from his bronzed face and lean-flanked, wiry body, nude save for clinging shorts and fiber sandals. "By the whirling rings of Saturn," he growled as he gazed disconsolately at his paper-strewn desk. "I'd like to have those directors of ITA here on Mercury for just one Earth-month. I'll bet they wouldn't be so particular about their quarterly reports after they'd sweated a half-ton or so of fat off their greasy bellies. 'Fuel consumption per man-hou