Europa

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:

This is the combination of colors (wavelengths) you are looking at when you see a Neon sign. Overall, it will look red due to the domination of red wavelengths. If you see a sign that is not red, it’s got a different inert gas in it but we still call them Neon signs for some reason. Argon and Xenon make blue, Krypton is white, Helium is purple.

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. 

Extremophiles

Ok, today’s Nerd Out is all about extremophiles. 

These are organisms that live under what humans deem to be extreme conditions. Perhaps they live in extreme heat, extreme cold, extreme pressure, extreme acidity…or under any other circumstance that would kill an “ordinary” living creature.

You can find extremophiles living in sheets of ice, near vents at the ocean floor, inside of volcanos…perhaps on a meteorite!

I’ll start by talking about my favorite extremophile, Water Bears.

Just look how cute they are! Doesn’t it kind of look like it’s smiling?

These are microscopic organisms with a body length of 1.5 mm. That’s about the thickness of a credit card.

They are called Water Bears because they live in water and they look like bears, duh. They also walk like bears. You know how bears kind of trudge along putting all their feet on the right side forward and then all their feet on the left side forward? That’s what these cuties do.  In fact, their scientific name is Tardigrada, which literally means slow walker.

Also, they have claws! Look:

They can move their claws swiftly the same way a cat does. Maybe they need to defend themselves from tiny microscopic bear hunters?

Water Bears (or tardigrades) are found all over the earth, and the reason is because they can survive pretty much everywhere. They are what’s called a polyextremophile which means they can survive in lots of different kinds of extreme circumstances.

FOR EXAMPLE, they can survive at a temperature of 35 Kelvin. Just to give you some perspective, at 35 K…oxygen is a solid. Oxygen ice. THAT’S COLD.

They can also survive temperatures up to 424 K, or 303 degrees Fahrenheit.

So there’s two extreme conditions under which Tardigrades are able to live. Survival in the hot temperature makes them hyperthermophiles and survival in the cold temperature makes them psychrophiles.

If you are biology-savvy you are probably thinking, “Wait…all living organisms need liquid water. How do Water Bears keep water from freezing or boiling in their cells?”. Many psychrophiles and hyperthermophiles dissolve certain proteins in their bodies to lower the freezing point and raise the boiling point of water. Also, under extreme pressures (like at the bottom of the ocean) the boiling point of water is raised.

Y’all are probably aware of how pressure changes boiling and freezing points…it’s the reason why you can boil water without getting it very hot when you are camping high in the mountains where the air pressure is lower. I’m not sure that this is what keeps water from freezing or boiling the Water Bears’ cells…but it might be! 

I do know this: Water Bears are capable of cryptobiosis. I think this is the same thing as being cryogenically frozen. I’m thinking of Austin Powers. It’s basically this form of preservation where all metabolic processes stop and you are in suspended animation. Water Bears will go into cryptobiosis after being dehydrated and can come back to life 10 years later.  Possibly longer! I don’t know if anyone’s ever tried for longer. Shit, I should find some of these guys, dry em out and check on them again when I’m old.

Ok, so we talked about how they can stand high/low temperatures and dehydration…let’s talk about how they can live in extreme pressures.

Water Bears can survive vacuum. That means no air. Zero pressure. IE: what it’s like in outer space. If humans were to be in the vacuum of space, our blood would boil (cause remember, stuff boils quicker at lower pressures). 

Wired Science listed Tardigrades (Water Bears) as #10 on their list of weirdest things launched into space in 2008. They withstood vacuum AND intense solar radiation then came back to earth in perfect health and were able to produce viable offspring.

They can also survive outstandingly high pressures.  They have been shown to survive in a cryptobiotic state at a pressure of 6,000 atmospheres. To give you a frame of reference, that pressure would definitely crush a submarine.

TARDIGRADES! YOU ARE SO FREAKING COOL!

I like to imagine that tardigrades came to earth from a meteor impact.  I mean, they could survive all the things they would need to in order to stay alive on a meteor. Are they aliens? Maybe these kinds of extremophiles were the seed to all life on earth and we’ve just evolved to be less and less extreme because we don’t need to survive in all those crazy circumstances. Who knows? Not me.

What other kinds of extremophiles are there?

Let’s talk about acidophiles. There are some organisms that prefer to hang out in pools of sulfuric acid. Yeah, sulfuric acid…you know, the stuff that will melt your face? It’s what happened to Two-Face.

Chemists use sulfuric acid as a drying agent because it removes water. In fact, when sulfuric acid reacts with water it releases lots of energy in the form of heat. This is why people get acid burns.

So why aren’t acidophiles getting burned?

They survive by constantly removing hydrogen ions from their bodies at a very high rate. I think that the reason this helps them is because the hydration of sulfuric acid is thermodynamically favorable. That means the sulfuric acid really wants to pick up the hydrogens that H₂O has to offer. Maybe the acidophiles eject lots of hydrogen ions as a sort of distracter for the sulfuric acid. Like, “hey don’t take my water…eat this instead!”. I’m not sure, I’m not going to pretend that I know enough chemistry to explain this fully but that seems right to me.

My favorite acidophile is ferroplasma acidarmanus. It’s a microbe that lives in acid and eats iron. Bad. Ass.   

They were discovered by a scientist named Katrina Edwards in the 90s when people were trying to figure out why iron mines were so damaging to the environment.

Here’s the story: sulfide is found naturally in metallic ores. Around iron mines the conversion of sulfide to sulfuric acid is greatly accelerated and no one knew why. This is a problem because it’s not very nice for the environment to have lots of acid run-off from mines. In fact, it has cost mining companies billions of dollars in environmental damage.

So, what’s going on?

As I said earlier, these critters eat iron so they will surely be found in abundance around mines where lots of iron is exposed. Turns out, they are the ones responsible for transforming the sulfide (which is just a negatively charged sulfur ion)  into sulfuric acid. Probably by ejecting all those hydrogen ions. I’ll bet the sulfide picks up 2 of those hydrogens that it’s spitting out and gets four oxygens from the air to make H₂SO_4. 

So this is a microbe that hates the environment. And eats metal. And lives in acid. It's like a bad guy from Captain Planet.

Ferroplasma acidarmanus forms a green slime. Check it:

The thing that is remarkable about this microbe is that it seems rather fragile. By that I mean, it doesn’t have a cell wall to protect it from the damaging effects of acid. It thrives in acid, it even makes more acid for itself to hang out in, but in all other repsects it's a rather delicate microbe. 

You know where Ferroplasma Acidarmanus would love to live? Jupiter’s moon Europa where there is lots of sulfuric acid frozen on the surface. I’m sure I will nerd out on Europa soon. It’s one of my favorite things to learn about.

Or what about Venus where it rains sulfuric acid? 

Check it!

Anyway, perhaps you are seeing a pattern? Extremophiles could be the most likely organisms to exist on other planets. I mean, if they can thrive in these kinds of hostile and “unearthly” habitats, why couldn’t they exist in more volatile places in the solar system? 

Tardigrades could certainly live on Mars, at least for a little while. Maybe they already do…

There are lots more extremophiles I could talk about! I didn't even delve into all the ones that live around thermal vents on the ocean floor. Maybe next time! 

Transparent Aluminum

Remember in Star Trek IV when Scotty gives that dude the recipe for transparent aluminum? Well, I just found out that clear aluminum exists. Life modeling art, perhaps? I wonder sometimes…

I think that Star Trek and other sci fi classics have been giving nerds with know-how ideas for new technology for years. The flip phone for example...tell me that wasn't inspired by Kirk's communicator. Sliding doors, like the kind they have in the grocery store: Star Trek all the way. 

Anyway, clear aluminum! How cool. Imagine what a strong window you can make, with really thin panes! Or if you could see your canned food from the outside, what would that be like? No more shaking it and making a guess when the label has been peeled off. Clear aluminum would certainly make dumpster diving easier. And clear aluminum foil?? HOW COOL. Just sayin.

So now I'm about to nerd out on transparent aluminum. I have to start with why things are transparent in the first place. 

Ok, let's start with glass. Why is glass see through? It's no news that glass is made from sand, which is a silicate. They melt it down and the individual molecules start moving in random directions because that's what happens when you heat stuff. 

The special thing about most solids is that they have a crystalline structure, meaning all the constituents, be they atoms or molecules, form a 3D repeating pattern. Think about a cube that you made out of sticks and balls of clay or something. The balls of clay are the corners. You can poke more sticks into the clay and keep this pattern going. Picture it: every ball of clay has six sticks coming out of it, two going to the balls of clay on top and bottom of it, two going to either side of it, and two going to the balls of clay in front and behind it. It’s like a bunch of cubes stacked on each other. There's a good model for the crystal structure of certain solids. 

The crystal doesn't have to look like a bunch of cubes, but it can. The kind of pattern a crystal makes depends on the solid you are talking about. Copper, for example has a face centered cubic structure, which means all the copper atoms hang out with each other in a pattern that looks like a die where all the sides are fives. Diamonds make tetrahedrons!

Quick aside: Don’t get confused when I say crystals. I’m not talking about the sparkly things you hang on your rear view mirror. I’m talking about the repeating pattern that the atoms that in a solid make. Yes, some crystal structures can have a resulting macroscopic solid the looks crystalline. For example, jewels and gem stones with repeating patterns of sharp edges, facets, and glittering faces. Most crystalline solids, however, form a jumbled array of microcrystals called grains. The microcrystals are so tiny that the crystalline nature of the solid is not visible to the human eye, but it’s very apparent as a dominant feature of the solid's structure when magnified some 2500 times.


Anyway, glass is what’s called an amorphous solid. This means that it doesn’t have a crystalline structure. It’s a little more like a liquid because after the sand gets melted down and the molecules start moving around chaotically, glass makers then cool the molten glass rapidly before the molecules have time to organize themselves into a crystal pattern. The particles freeze in a random pattern. The way that the molecules bond with each other is all disorganized and crazy; it's no longer a stack of microscopic cubes.


Basically, as long as something is heated up really hot and then cooled rapidly before the molecules have time to arrange themselves in a crystal pattern, it’s an amorphous solid. Other amorphous solids include wax, rubber, certain kinds of clear candy, and plastics. 


OK, So what makes it see-through? This is actually a two parter. Part one: Now that the crystals aren't neatly stacked, there are gaps and holes. It’s the difference between stacking your legos neatly in the box and just throwing them all in there. One of those ways is going to take up more room because there are spaces in between the blocks. Light can get through these gaps. That is, of course, if the light is of the right wavelength to fit through the hole. In the case of glass, visible light has a wavelength that seems to be comparable to many of the holes. That’s partially why the visible light can get through, or be transmitted. 


One way of filtering certain types of light is by slowing down the cooling rate and allowing the glass to form crystal patterns. This can block out Ultra Violet light, for example. People that make sun glasses have this down. I’m pretty sure this is not why transparent aluminum is see-through, though. At least it's not the only reason. 

So of course, there is more to being transparent than being an amorphous solid. Diamonds, for example, are transparent but they quite famously form crystal structures. One might argue that they are the ultimate crystal.

The transparent properties of a material are all about the band gap. This is where shit gets crazy...


We all learned about electrons living in their own shells, or orbitals, around the nucleus of an atom in high school, right? The distance an electron is away from the center of an atom (this is called it’s orbital radii) is determined by it’s energy. These orbitals are quantized energy states.


What does that mean?


The popular analogy here is to think of it like stair steps but I’m gonna make up my own. 


We are used to this continuous way of life where I can stand on this side of the room, or that side of the room, or anywhere in between this side and that side of the room. But that doesn’t work in an electron's world. They follow different rules than us. You can either be on this side of the room or that side and there is NO in between. So an electron’s energy is quantized, it comes in packets where you get it all at once or it gets taken away all at once.


This is exactly what is happening when electrons hop up to higher or lower energy states. 


How? 


With photons! Photons are the particle that is associated with light. They are massless bundles of pure energy. If an electron absorbs a photon it gets all of it’s energy and if it ejects a photon it loses energy equal to the energy of the ejected photon. This will put it in a different orbital.


The energy of a photon depends on the wavelength of the light that it comes from. The bigger the wavelength, the smaller the energy.


Anyway…back to the band gap. Basically, it’s a difference between the energy levels of two groups of electrons. The two groups are called the conduction band and the valence band. A solid is a good conductor (meaning electrons have an easy time moving inside of it) IF AND ONLY IF the band gap is small. The valence electrons have every opportunity to hop up to a higher energy level…the next one up is so close, after all. That means the electrons are very likely to absorb an incoming photon and hop up into the conduction band. Once an electron is in the conduction band it’s free to cruise around and make TVs work and stuff. Current is the working name for electrons moving over the face of a solid, btw.


SO, the band gap is pretty small in things that are good conductors. Metals tend to be good conductors. Hm, metals also happen to be the opposite of transparent. They are reflective. Shiny. Including aluminum, it’s a great conductor with a very small band gap.


WHY SHINY: As I mentioned, all the photons that hit the metal get absorbed by the electrons because they have a really easy time jumping over the small band gap into the next energy level. Since light is an electromagnetic wave, the electric field of the light induces a current in the metal which ejects the incoming photons back out immediately and the surface appears reflective if the metal is smooth. If it’s not smooth the metal will have a dark appearance because all the incoming photons are getting absorbed instead of reflected or transmitted. 


How cool is that? I love thinking about how the appearance of everything we can see is just the result of photons interacting with electrons and crystal structures of solids. 


Ok, so that’s why things are shiny but why are they transparent?


If the band gap is large (as it is in insulators, the opposite of conductors) the electrons can’t absorb any photons because they don’t have the option of jumping to a higher energy state. That means the photons go right through the crystal structure of the solid with out being absorbed by electrons along the way. 


The size of the band gap determines what kind of light will be transmitted and what will be reflected; Because remember, the band gap is an energy difference...energy of light is determined by it's wavelength...wavelength determines the type of light we are talking about. What kind of light will this object transmit and what will it reflect? Red? Blue? Infrared? X-rays? Depends on your band gap! 


Maybe this is a stretch, but it just occurred to me: the atmosphere is made of stuff that is transparent to visible light but opaque to infrared light. That's the whole reason the green house effect exists. So, the molecules in the atmosphere must have a band gap with a smaller energy than visible light but the same size as infrared light. Or maybe you can't think of it like that because the atmosphere is a gas and not a solid. Who knows? Not me! 


That was a lot of stuff. Good review session for me, for reals. 


Ok, so how did they make aluminum, which should be shiny, as it is a metal and good conductor, the opposite of shiny? Also, does that mean that it no longer has conductive properties? This is what I needed to find out. 


So, according to phys.org they used an extremely high powered and teeny tiny focused x-ray laser. (aside: you know laser is an acronym, right? Love it.) When I say teeny tiny I mean a twentieth of the diameter of a human hair. They managed to use this laser to kick out a core electron. That means, they removed an electron that is not a valence electron. So, it was somewhere deep inside the electron cloud and not an electron that usually gets messed with in regular chemical reactions. They were able to do this without disturbing the crystal structure of the aluminum.


How did that make it see-through? I can only assume that by removing a core electron the rest of the electrons switched around and ended up in an arrangement that gave it a much bigger band gap. Not sure. 


I seem to have reached an impasse so I emailed my physics prof. Maybe she can explain it to me!


That's enough nerding out for now. See you next time!

My intentions...

So now I'm a blogger! 

Here's Why:

I really love research projects. They are my favorite. I love learning about certain things or NERDING OUT, so to speak, so I thought I would create a space for myself to do that and share my brand new knowledge with a greater community. Maybe people will even read this and tell me all kinds of cool stuff I don't know about yet! 

Here we go!