Compton Spectrometer and Imager
Artistic rendering of COSI | |
| Names | COSI SMEX-17 |
|---|---|
| Mission type | Gamma-ray astronomy |
| Operator | University of California, Berkeley NASA |
| Website | https://cosi.ssl.berkeley.edu/ |
| Spacecraft properties | |
| Spacecraft | COSI |
| Payload mass | < 400 kg |
| Start of mission | |
| Launch date | August 2027 (planned) |
| Rocket | Falcon 9 |
| Launch site | Cape Canaveral Space Force Station |
| Contractor | SpaceX |
| Orbital parameters | |
| Reference system | Geocentric orbit |
| Regime | Low Earth orbit |
| Main Germanium detectors | |
| Name | Compton telescope |
| Collecting area | 25% field of view of the sky |
| Transponders | |
| Band | Gamma Rays |
| Bandwidth | 0.2–5 MeV |
Logo of COSI with all the participating institutions. | |
The Compton Spectrometer and Imager (COSI) is a NASA SMEX astrophysics mission that will launch a soft gamma-ray telescope (0.2–5 MeV) in 2027. It is a wide-field compact Compton telescope (CCT) that is uniquely suited to investigate the "MeV gap" (0.1–10 MeV). It provides imaging, spectroscopy, and polarimetry of astrophysical sources, and its germanium detectors provide excellent energy resolution for emission line measurements.
The germanium detectors have an instantaneous field of view of more than 25% of the sky, and they are surrounded on the sides and bottom by active shields, which provide background rejection while also allowing for detection of gamma-ray bursts and other gamma-ray flares across the majority of the sky.