NASA has announced that it has chosen a new proposal for an additional space telescope that will be used to study the recent history of star birth, star death, and how chemical elements within our galaxy formed. The mission is a GammaRay telescope called the Compton Spectrometer and Imager (COSI).
Currently, NASA expects COSI to launch in 2025, and the mission is the latest small astrophysics mission from the agency. The Astrophysics Explorers Program received 18 different proposals for telescopes in 2019, with four selected for mission concept studies. NASA investigated each proposal in-depth and ultimately chose COSI to continue into development.
For decades NASA has sought opportunities for smaller-scale missions specifically to fill gaps in our knowledge of the cosmos. COSI will help scientists better understand the origin of chemical elements in the Milky Way, which also helped form the Earth as we know it. The mission will study gamma rays produced by radioactive atoms after massive stars explode.
COSI will map where chemical elements formed within the Milky Way and investigate the origin of positrons in the galaxy, also known as antielectrons. Antielectrons are subatomic particles with the same mass as electrons, but they have a positive charge. The principal investigator for COSI is John Tomsick from the University of California Berkeley.
NASA expects the mission to cost $145 million, plus launch costs. Currently, NASA has not chosen a launch partner. The technology used for the mission has been developed over the past decades using flights on scientific balloons. In 2016, an early version of the GammaRay instrument was taken aloft by the NASA super pressure balloon designed to lift heavy objects for long durations.