This paper describes development of and test results for an electrostatically switched radiator (ESR). This is a device that can control the radiation emitted from a surface by controlling the position of a thin membrane. The present structure has been fabricated for flight testing on NASA’s ST5 New Millennium program. It consists of 4 separately controlled radiator sections with a total active area of 57.6 cm2. As opposed to the original approach, this structure has the outer membrane at ground potential and is constructed onto a printed circuit board. In this paper we discuss the current state of development of the ESR, including device fabrication and test results. © 2004 American Institute of Physics