Europa, one of Jupiter’s largest moons, has long been considered a prime candidate in the search for life-supporting environments within the Solar System. Although its surface is an icy shell, scientists believe that beneath it lies a deep, salty liquid ocean surrounding a nickel-iron core. Europa is heated internally by tidal flexing caused by Jupiter’s gravity, which generates enough energy to keep the ocean from freezing completely. This process also forces water and dissolved materials upward through cracks in the ice, reshaping the surface through cryovolcanic activity. Recent findings suggest that this subsurface ocean may be even more chemically intriguing than previously thought.

Data collected by NASA’s Galileo spacecraft between 1995 and 2003 hinted at the presence of ammonia on Europa, but only recently have researchers confirmed it. By reanalyzing measurements from Galileo’s Near-Infrared Mapping Spectrometer, NASA/JPL scientist Al Emran identified faint ammonia absorption features at a wavelength of 2.2 microns. These signals were detected near surface fractures, which are believed to be pathways allowing liquid water to rise from the ocean below. Because ammonia is quickly destroyed by radiation in space, its presence indicates that the material was brought to the surface relatively recently in geological terms.

Ammonia (NH₃) contains nitrogen, a key element for life as we know it, essential for forming amino acids, proteins and DNA. While ammonia alone does not prove that life exists on Europa, it strengthens the case that the moon’s ocean could be chemically hospitable. Ammonia also lowers water’s freezing point, influencing the ocean’s physical and chemical behavior and potentially supporting long-term liquid conditions.

Ammonia is not unique to Europa; it has been detected on other icy bodies such as Pluto, several Uranian moons, Titan, and in plumes from Saturn’s moon Enceladus. However, confirming its presence on Europa is significant because it highlights active geology and ongoing exchange between the surface and subsurface ocean. These discoveries are especially important for NASA’s Europa Clipper mission, launched in 2024 and set to arrive in 2030, which will investigate Europa’s habitability, ocean structure, and surface chemistry in unprecedented detail.

To find out more about Europa’s ocean and its life, read the article by NASA.