Satellite imagery provider Space Imaging, of Denver, Colo., has appointed Charles Stees as CFO and Mark E. Brender as vice president of corporate communications.   . . .   Waltham, Mass.-based Thermo Electron Corp., a provider of high-tech instruments, has appointed Peter Manning to its board of directors. Manning recently retired from FleetBoston Financial.   . . .   Ultratech Stepper Inc., a San Jose, Calif.-based supplier of photolithography systems used to manufacture semiconductors and nanotechnology devices, announced it has received a multiple-system order for its Saturn Spectrum 3e tool from Tokyo-based Casio Micronics Co. Ltd., a merchant gold-bump foundry. Casio will use the tools to perform gold-bump processing on device drivers for liquid crystal displays. Delivery is scheduled for the second quarter of this year.