The Compton Spectrometer and Imager (COSI) mission, a small research satellite, is scheduled to launch on a SpaceX Falcon 9 rocket in 2027. This satellite is designed to study the violent processes behind the creation and destruction of chemical elements, focusing on supernova explosions and the formation of heavier elements through nucleosynthesis. The data collected by COSI will help scientists map the locations where these elements are being formed within the Milky Way galaxy.
COSI will also investigate the annihilation of positrons, the antimatter equivalent of electrons, which seem to be originating from the center of the galaxy. Another key objective for COSI is to quickly report the location of short gamma-ray bursts, extremely violent explosions that last only a few seconds. These bursts are believed to be caused by merging neutron stars.
The COSI mission will be sensitive to soft gamma-rays, a relatively unexplored segment of the electromagnetic spectrum. The telescope is based on a design that has been flown on research balloon flights. NASA selected COSI in 2021 to become the next mission in its Explorers program, and the mission was formally approved to proceed into development for launch in August 2027, with an estimated budget of $267 million to $294 million.
COSI will be launched from Cape Canaveral, Florida, on a Falcon 9 rocket. The spacecraft, which weighs less than a ton and was built by Northrop Grumman, will operate in an unusual orbit about 340 miles (550 kilometers) over the equator to avoid interference from radiation. SpaceX was awarded a $69 million contract to launch the COSI mission, a 37% increase from the price paid for a similar launch in 2019, due in part to inflation.
In the coming years, NASA hopes that United Launch Alliance’s Vulcan rocket and Blue Origin’s New Glenn launcher will be available to compete for launch contracts for missions like COSI. All of ULA’s remaining Atlas V rockets are already booked by other customers.
