BARREL

NASA

On Cupid! On, Donner and BARREL!

In this image from Dec. 8, 2017, four reindeer walk past the Balloon Array for Radiation-belt Relativistic Electron Losses, or BARREL, payload on the launch pad at Esrange Space Center near Kiruna, Sweden. BARREL primarily measured X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are caused by electrons that rain down, or precipitate, into the atmosphere from…