NASA’s Juno mission measures the amount of oxygen on Europa. Jupiter’s ice-covered moon generates 1,000 tons of oxygen every 24 hours—enough to keep a million people breathing for a day. But the rate of oxygen production on Jupiter’s moon Europa is significantly slower than most previous studies. The results, published March 4 in the journal Nature Astronomy, were obtained by measuring hydrogen evolution from the surface of Jupiter’s icy moon using data collected by the Jovian Auroral Distributions Experiment (JADE) instrument.