TO ENABLE CONSTRUCTION OF NEXT-GENERATION HARD X-RAY TELESCOPES THIS PROJECT AIMS TO (A) DEVELOP CO- NI- AND PTBASED X-RAY MULTILAYER COATINGS HAVING HIGH REFLECTANCE UP TO ~200 KEV IN ORDER TO MAXIMIZE TELESCOPE EFFECTIVE AREA AND EXTEND ENERGY COVERAGE BEYOND NUSTAR AND (B) DEVELOP TECHNIQUES TO MITIGATE MULTILAYER-COATING-STRESS-INDUCED DEFORMATION OF THIN-SHELL MIRROR SUBSTRATES IN ORDER TO ACHIEVE HARD X-RAY TELESCOPE ANGULAR RESOLUTION OF 15 ARC-SECONDS OR BETTER.