The Jovian moon of Europa is surrounded by plenty of mystery and lots of speculation. Slightly smaller than our own moon, it is composed largely of silicate rock with a tenuous exosphere of molecular oxygen and a possible iron core. The surface is predominantly made of ice and while it is checkered with streaks and fractures it is in fact one of the smoothest in the whole solar system. This smooth but variegated surface resembles images of sea ice as seen on Earth and has led many planetary scientists to believe that there is a vast subsurface ocean of liquid water below the frozen crust.
Tentative evidence for this ocean can be seen by looking at what has been termed ‘chaos terrain’, an area where some believe the subsurface ocean has melted through the icy exterior due to tidal up-welling. Other evidence can be found in the data that the Galileo probe obtained, showing that Europa has a weak magnetic field induced through Jupiter’s own, suggesting the presence of a conductive sub layer i.e an ocean of liquid saltwater .
If indeed there is an ocean under the frigid surface, then it is plausible to think that extraterrestrial life might exist, but what kind of life? This proposition hinges on one fact: the temperature of Europa’s ocean. While the moon may possess an internal energy source, it is insufficient to provide the necessary heat to help maintain biological processes. However, the orbital resonance between Jupiter, Io, Europa and Ganymede probably heats the interior of the moon through tidal flexing which would ensure that the ocean remained liquid. The energy from the tidal flexing could also possibly be released through hydrothermal vents much like the black and white smokers that are found on Earth’s ocean floor. Europa’s hydrothermal vents could provide the ideal conditions for a more modest ecosystem than those found around Earth’s vents but they would support a hot, nutrient rich environment in which micro organisms like anaerobes and archaea could potentially thrive.
The only way that we will know for sure what lies beneath Europa’s mysterious surface is by going there, and it looks like we’re going to get our chance. NASA and ESA announced near the end of last month that they were going to undertake a joint mission to launch two probes by the end of the next decade to study Jupiter and it’s four moons. Just what discoveries will be made about Europa is anyone’s guess, but they’re sure to be extremely exciting and very compelling.
This reminds me of the movie 2010 - The Year We Make Contact (sequel to 2001 - A space odyssey). They discover some form of life there on Europa. I love that scene!
You know, one has to be aware with such discussions that life is not confined to the narrow definitions of Earth scientists. In the last few years just on Earth itself there have been many discoveries of strange creatures and life forms that had not been though possible before. There could be species that don’t need oxygen, photosynthesis, carbon etc. Who knows? Maybe not a point in case but this makes me recall a story of transparent, eyeless critters found in a deep and inhospitable cave environment (I believe in Israel).
Hi Dennis, I’m glad you enjoyed the post. 2010 certainly is a fantastic, thought provoking movie and a worthy sequel to the cult classic 2001: A Space Odyssey. While I share your enthusiasm for the discovery of new life here on Earth I think that the likelihood of finding multicellular extraterrestrial life within our own solar system is completely non existent.
Microbial life or to be more specific: extremophiles i.e. archaea & bacteria offer the best prospects for finding life on Mars, Europa, Enceladus & Titan. These organisms thrive in physically harsh environments that are otherwise inimicable to the majority of terrestrial life. One example of this can be seen when a colony of Endoliths were found inhabiting a South African gold mine 2 miles below the surface of the Earth. These organisms live in complete darkness and deal with extreme temperatures as well as intense pressure. They are also capable of using inorganic chemicals present in rock to synthesize all the organic compounds necessary for life.
While the direct discovery of extraterrestrial life beyond our own solar system is all but impossible with our current technology, I am certain that it will be carbon based life that we find on other worlds out there. The interstellar medium is awash with the fundamental chemical elements (hydrogen, oxygen, carbon, nitrogen, sulfur & phosphorous) required to produce organic molecules which can be found in comets, stellar clouds and meteors. The important thing with carbon is that it can bond with up to four other atoms including itself, which allows for the creation of stable complex organic molecules. Silicon has long been touted as an alternative to carbon and does have similar chemical properties but it’s complex molecules offer an inconsistent basis for organisms to develop. The Earth itself has abundant quantities of silicon and is carbon poor, yet carbon based life flourishes. This fact alone goes some way to confirm that life elsewhere in the universe must be carbon based.
If we can find primitive life on other worlds in our own ‘backyard’ then it would redefine our place in the cosmos and widen the scope for alien life beyond our own solar system.
Thanks for your comment,
Ewan