On Saturn’s small moon Enceladus, perpetual fountains of alien seawater launch all sorts of curious stuff into space: water, salt, silica, and even simple carbon-containing compounds fly into the void—many of which are ingredients for life as we know it.

Now, scientists working with data from a dead spacecraft have discovered something even more potentially intriguing: heavy organic compounds containing hundreds of atoms arranged in rings and chains. These are the most complex organic molecules uncovered so far at Enceladus, and—sorry, Europa—they may make the moon the most promising place in our solar system to search for life beyond Earth.

“What we know today is telling us that Enceladus is an outstanding target to go look for life, and