WASHINGTON – U.S. Naval Research Laboratory scientists launched the second Strontium Iodide Radiation Instrument (SIRI-2) instrument in December 2021 onboard Space Test Program (STP) Sat-6. SIRI-2, a gamma-ray spectrometer, will demonstrate the performance of europium-doped strontium iodide gamma ray detection technology with sufficient active area for U.S. Department of Defense (DoD) operational needs.
The first SIRI mission was launched on December 3, 2018, onboard STP Sat-5 with a one-year mission to investigate the detector’s response to on-orbit background radiation in low Earth orbit (LEO). The much larger, SIRI-2 instrument is operating in a geosynchronous orbit, where the radiation background is significantly different in composition.