As promised in my extremophiles blog, here is the Europa blog you’ve been waiting anxiously for.
What is Europa?
It’s a moon of Jupiter!
Europa is one of the (at least) 63 natural satellites of Jupiter. Galileo spotted it through his telescope in 1609 and you can see it too if you look at Jupiter through a telescope. Here’s what you might see:
That’s Jupiter and the three other Galilean satellites: Io, Ganymede, and Callisto. These are the big ones, some of them are even bigger than planets in our solar system.
Europa is about the size of our moon which makes it bigger than Pluto and about 70% of the size of Mercury. Not too big but still, it’s got lots going for it.
I’ll tell you straight up, the reason I like Europa so much is because it’s the best candidate for life (as we know it) in the solar system. Check out the close-up:
See the cracked blue surface? That’s ice. Water ice! It’s been hypothesized that underneath the icy crust, there is a wide spread liquid ocean warmed by volcanic vents. On Earth there are entire communities of species that thrive near ocean-floor hydrothermal vents. It’s entirely possible that the same thing is going on under Europa’s ocean.
Ok, but why do we think there is an ocean?
First of all, there is lots of evidence that Europa is resurfacing. IE: water is seeping up through those cracks and freezing on the surface.
For instance, compare Europa to our moon:
See all the holes and dents? Those are craters from meteor impacts. Europa should look like that too as it is just as likely to get hit by space stuff as the moon. Even more likely, in fact, because it’s next to Jupiter which is so massive that it sucks lots of passer-byers into it’s orbit. The fact that it doesn’t look all pock marked is evidence that the surface is relatively new. The craters have been washed away.
Want some more evidence for resurfacing? Ok, well…Europa has a much higher albedo than the other icey moons around it. That’s science talk for it’s much shinier. Ice darkens in space over time. It shouldn’t be that shiny unless the ice is new.
What other evidence is there for an ocean?
Europa has a significant magnetic field. You don’t get one of those unless you have an electrically conducting liquid on the inside. Earth’s magnetic field comes from our molten iron core. It’s possible that Europa’s magnetic field is caused by a very salty ocean, with the ions from the salts providing the conductivity. Either that or it’s got a molten core…also good for the case of an ocean warmed by under sea volcanoes.
We can get clues about Europa’s interior structure based on what kinds of chemicals are present on the surface.
How do we know what chemicals are present on the surface?
Well, every element has a certain “finger print”. You can tell what you are looking at based on it’s emission spectra, the light it’s giving off, basically. This has to do with the way the electrons lose energy and eject a photon on their way down to a lower energy state. I talked about this a little bit in my transparent aluminum blog. The amount of energy that an electron loses as it falls back down to a ground state is exactly the energy of the photon it ejects. The energy of a photon is what determines its wavelength. Each element emits a combination of different wavelengths that is completely unique. This is because each element has a distinct electron configuration.
So the moral of the story is: want to know what your looking at? Look at the wavelengths it emits or absorbs.
Here is the emission spectra of Neon, to give you an idea:
Anyway, now that y’all know how it works…using spectral analysis, we’ve found carbonates and sulfates (both salts) on the surface of Europa. The saltiest areas are the also the ones that appear the freshest. I’ll spell it out for the dummies: salt water seeped out of the cracks and refroze into these fresh spots! Well, it’s possible anyway.
Hey, wait a sec…did I say carbonates? Carbon! The basic building block for life (as we know it) is present in abundance on Europa. That. Is. Rad.
So, what kind of life would we find on Europa?
Well, it couldn’t depend on photosynthesis because it’s way too far from the sun – plants just won’t grow there. Chemosynthesis would have to be how life gets by. This is a process of producing energy utilized by several organisms living near hydrothermal vents on the bottom of Earth’s ocean. Basically, biomass gets created from the oxidation of the chemicals spewing up from the volcanic vents. It’s a way of getting energy that has nothing to do with the sun.
Bill Nye named chemosynthesis as one of the 100 greatest scientific discoveries of all time. Probably because up until the 70s we had no idea that life could exist that didn’t depend on photosynthesis. I mean, when you think about it…EVERYTHING lives because of the sun. Meat eaters eat animals that eat plants that photosynthesize due to sunlight. All the food chains we knew about begin with photosysthesis. When scientists first discovered all the life on the bottom of the ocean that is surviving independent of the sun, it was a total shit show.
Aside from chemosynthesizing, Europan life would also have to be mobile. Since volcanic vents don’t last forever, they would need to be able to migrate from vent to vent.
We might get a clue for what kind of life could exist on Europa by studying Lake Vostok, a huge fresh water lake underneath 13,000 ft of ice in Antarctica. This lake has been completely untouched for 5 million years, so whatever life might exist down there has evolved independently of everything outside of it. But before we drill into it and check out what kinds of creatures are down there, we need to get to work on developing ultraclean technology so we don’t contaminate the unspoiled, ancient ecosystem.
Maybe once we have that ultraclean technology we can take it to Europa! Probably not anytime soon though... proposed missions to Europa have been haunted by budget cuts and pushed so far into the future that it seems unlikely that we’ll ever get there. I guess it’s way more important to spend money on war.
Anyway, if we did send a probe to Europa, here’s what some artist thought it might look like:
But I like to think it would look like this:
I labeled things for the people who aren’t able to correctly interpret my breath-taking artistic abilities. The blue things living near the volcanic vents are the central nervous systems of a chemosynthesizing species I have conceptualized. They are basically soft brain matter protected by a shell. They communicate with the detached, moving parts of their body via brain waves. The moving parts swim around swiftly by moving their flagella and bat-like wing-fins. The central nervous systems are capable of modulating the brain waveforms to give the detached body parts any order. It’s similar to the way our brains tell our arms and legs to walk or dance or kick, except it’s a signal that is transmitted through the water rather than being directly connected to the brain by a nervous system. The part of the detached body that receives the brain wave signal is shaped like a star.
There is also a predatory species that grows downward from the bottom of the ice. These predators look like long tentacles and are able to control their interior pressure to create dramatic pressure differences between the outside and inside of their bodies. They can create near-vacuum inside of their bodies and suck in whatever unfortunate Europan creature happens to be swimming by. They digest by putting their captured prey under high pressure and squeezing out all nutrient-rich liquids. Their waste products are what the brain species mold their protective shells from (after super-heating by the volcanoes and reforming).
The brain species are a highly intelligent and sensitive life form. They are able to interpret brain waves of not only themselves but of any other species. As an artifact of what is basically telepathic communication, they are capable of deeply understanding the needs and desires of other living creatures. They have lots of valuable wisdom to share with the universe.