2 May 2024
The Compton Spectrometer and Imager (COSI) is a NASA Astrophysics Small Explorer satellite mission that will perform gamma-ray measurements in the 0.2 – 5 MeV bandpass. COSI has been confirmed and is proceeding to Phase C. The Key Decision Point (KDP) review occurred on 16 April 2024, and the KDP-C Decision Memo was signed shortly after. This marks the end of the mission formulation phase and the start of implementation.
After its planned launch in 2027, COSI will make all-sky maps of nuclear and annihilation emission lines, including studying the glow of 511 keV positron annihilation emission from the central Milky Way Galaxy. COSI will also measure the gamma-ray polarization of sources such as accreting black holes and provide rapid gamma-ray burst localizations.
The mission's principal investigator (PI) is John Tomsick at UC Berkeley. Other institutions involved in the upcoming phase of the mission include the Naval Research Laboratory, Goddard Space Flight Center, Northrop Grumman, Space Dynamics Laboratory, Lawrence Berkeley National Laboratory, UC San Diego, Clemson University, Louisiana State University, and international partners in Italy, France, Germany, and Japan. COSI is part of the Explorers Program portfolio managed at Goddard Space Flight Center.
For more information, please visit the Explorers Program and COSI websites.