273 — Evidence of a plume on Europa from Galileo magnetic and plasma wave signatures

On September 21, 2003, the Galileo spacecraft, which had been studying Jupiter for eight years, plummeted into the Jovian atmosphere, and that was the end of the mission.

HA JUST KIDDING; ¡SCIENCE!

Galileo continuously transmitted data back to Earth until it was physically incapable of doing so, and that dataset is still largely unexplored.

The idea that Europa — a moon of Jupiter — has oceans underneath its icy surface — continues to fascinate researchers. It has been widely thought that another probe will need to arrive at Europa in order to definitely decide if the moon is releasing “plumes” — sure evidence that the moon contains liquid water. (Here’s a video of a lecture I attended at the Space Telescope Science Institute, where I had the opportunity to ask a question of expert Dr. Susana Deustua.)

But it turns out that another probe — still welcome — is perhaps unnecessary, as Galileo’s decade-old data is still revealing new truths about this moon. Galileo passed within 400km of Europa; close enough, it turns out, to experience dramatic changes in recordings from magnetometers and plasma wave spectrometers: These changes coincide with our expectations for plumes, which suggest evidence of planet-wide oceans underneath the icy crust.

This is, as scientists say, “crazy awesome.”