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Recent News: In August 2019, we proposed the satellite version of COSI as a Small Explorer (SMEX).  On March 16th, 2020, it was announced that COSI-SMEX was selected for a Phase A study!  The NASA press release is here.   Work on the Phase A study will begin soon, and we are expecting it to be due in early 2021.


COSI is a balloon-borne soft gamma-ray (0.2-5 MeV) telescope designed to study astrophysical sources of nuclear line emission and gamma-ray polarization. Learn more by reading about the Science behind COSI, its Design and related Publications.

The COSI Team launched the instrument from Wanaka, New Zealand, in May 2016 aboard a Super Pressure Balloon.  Learn about the work in their Blog PostsTwitter FeedFacebook Wall, or in the News.