NASA’s Galileo Mission Points to Ammonia at Europa, Recent Study ShowsIn this composite image, red pixels mark locations on Europa’s surface where ammonia-bearing compounds were detected; purple indicates no such detection. Captured by NASA’s Galileo mission in 1997, the data is overlaid on a black-and-white mosaic that zooms in on a portion of the moon’s surface. NASA/JPL-CaltechNew analysis of decades-old data has turned up a significant result: the first discovery of ammonia-bearing compounds on the surface of Jupiter’s moon Europa. Hidden in the data were faint signals of ammonia near fractures on the moon’s frozen surface, through which liquid water containing dissolved ammonia compounds would be expected to rise. It also provides a tantalizing target for follow-up by the Europa Clipper mission, which arrives at the Jupiter system in April 2030.