Challenge the Hellmaker (1976) by Walt & Leigh Richmond

CHALLENGE THE HELLMAKER is an intriguing novel by a husband and wife team of scientists who have been absent from the science fiction world for too long. Drawing on their exhaustive knowledge and imagination they have conjured up a near-future world dominated by the repressive U.N. Security Corps. The only barrier to its total dictatorship is a small group of international scientists isolated on a space station miles above the Earth... and the Hellmaker.