It has been theorized that Europa’s oceans may be similar to Earth’s seas. While sulfate salts were thought to dominate Europa’s oceans, Hubble Telescope detected NaCl presence on Europa’s surface. This is exciting since Earth’s oceans get their salty taste from NaCl too. Samantha Trumbo of Caltech, Pasadena stated that Europa’s internal geochemistry and surface composition theories required a revision. If NaCl could be an indicator of internal composition of Europa, then Europa’s oceans are likely to be similar to Earth.
Galileo spacecraft that had orbited Jupiter during 1995-2003 had spotted yellowish-looking patches on its surface. Irradiated NaCl was held to be a likely explanation for this. Trumbo and team started searching for NaCl via Hubble’s STIS instruments during May-August 2017.
Absorption lines at 450 nm were observed an irradiated NaCl presence sign. However, it wasn’t found across the planet. Rather, it was Europa’s Jupiter-facing side. NaCl was mostly found in chaotic and disruptive regions where it is likely that the ocean was spitting out material from within it.
Io, another Jupiter moon, often spat out sulfur compounds that devastated Europa’s trailing side. However, the Jupiter-facing side is shielded. It is suggested that this side could be the most accurate picture of Europa’s own material composition, Trumbo stated in her study. However, it is still very unclear. While NaCl’s origins were pretty much confirmed to be from its interiors, it remains to be seen if Europa’s interiors have NaCl widespread through them.
Sulfate salts are thought to rule Europa’s oceans and NaCl could simply be a minor player. Experiments conducted on Earth imply that Earth’s oceans started out as sulfate filled. Even today, meteorites expel sulfates when dipped in water. However, seafloor hydrothermal mechanisms could eventually cause NaCl concentrations to rise. If Europa does have such mechanisms in place, which are widespread through the Earth, they could also exist on Enceladus, Saturn’s moon with an icy, subsurface sea.