'Fireflies' help NASA map radiation around Jupiter and its moons 

 The first ever 3D radiation map of Jupiter and its moons has been created using low-light cameras aboard the Juno Spacecraft that have been tweaked to operate as radiation detectors.  

https://cdn.mos.cms.futurecdn.net/WMKLEmYy5rLSTh9A34xnWa.jpg

https://www.space.com/fireflies-help-nasa-map-radation-around-jupiter-and-moons