Ice Fishing

Ask anyone in the Astrobiology biz where's the best chance to find life beyond Earth, and most of them would suggest Europa, the second of Jupiter's four "Galilean" moons. (A few stubborn holdouts at the back of the room would still yell "Mars!") Europa is a good candidate for life because it seems likely to have liquid water in its interior, beneath a surface of ice. And now it seems Europa may have oxygen as well.

The strongest evidence for liquid water is Europa's smooth, young surface (just like the moon's mythological namesake). The surface of Europa gets "resurfaced" very quickly in geological terms, so it doesn't have many craters or mountains. Just lots of smooth ice. Planetary scientists interpret this to mean that the surface of Europa is merely a crust of ice, possibly several kilometers thick, atop a liquid or nearly-liquid interior. There is some debate: Europa could have an ocean of icy slush rather than liquid water. Either way, currents and upwellings apparently drag down old ice and replace it with new material very rapidly, on a timescale of only thousands of years.

But life does require other stuff besides water. Earth-style life, in particular, needs oxygen for any kind of large, active organisms. Since Earth's oxygen all comes from plants doing photosynthesis, and Europa has no sign of plants and gets far less sunlight, it seemed unlikely that the icy moon would have much oxygen. However, that may not be the case.

There are other sources of free oxygen: energetic photons can break up water or carbon dioxide molecules directly, if there's no pesky atmosphere to block them. This creates free oxygen. Europa's surface gets bombarded by radiation constantly, and the geologically rapid resurfacing of its icy crust means that oxygen gets dissolved into the ocean (if there is one). All this means that Europa's water would have as much oxygen as Earth's oceans do. Which means that, say, fish could live there. (Fish live in water, but they do need oxygen.)

This sounds like a job for the Minnesota Space Agency.

Comments

[fishing]

yeah, The surface of Europa gets "resurfaced" very quickly in geological terms