In the last essay, we talked about the possibilities of life on Europa and why it’s a good candidate due to the high probability of water beneath its surface. See, the thing about water is that it’s much easier to get life going in the water rather that outside of it. Life swam around the oceans of the young Earth for billions of years before making the trek onto dry land, and even then, that was a tenuous step that could’ve been reversed given proper circumstances. Indeed, some animals went back to the oceans. Today, the animal we call the baleen whale has the remnants of hind legs buried deep within the back of its body. For the ancestors of some whales, moving on up to the dry side wasn’t such a hot idea after all.
And you know, evolutionarily speaking, it worked out for them. After all, these days the whales are not only some of the largest animals in the oceans, but also in the world. The biggest animal on the face of our planet is the blue whale, an animal so big that it couldn’t survive on land if it ever decided to try the dirt again. In the oceans, the whale has few predators and the larger whales haven’t any natural predators at all. The only thing capable of preying upon them, unfortunately, is us.
Swimming, swirling, and gliding through the waters of the oceans and seas and lakes and rivers is a vast swath of life and much of it isn’t even understood today. Things can disappear and hide down there for years, decades, even centuries. The most popular example of this is the coelacanth, a fish thought to have been extinct since the Cretaceous, 65 million years ago. Then a fisherman caught one off the east coast of South Africa in 1938 and tossed a serious wrench into that belief. The absolute alien nature of some deep sea life defies the imaginations of science fiction and fantasy writers the world over.
There’s a fish, a really scary looking fish, called the barreleye. It’s a sort of standard looking fish, small and unassuming. The non-standard thing about it is the transparent head. Its eyes float around inside the skull and it can literally look up through the top of its head. It’s able to control those eyes too. Floating quietly in the water, maybe 2,000 feet down, it watches overhead for stuff to eat. Once it spots something, it rotates the eyes to the front of the skill and goes for it.
Another fish, the aptly named viperfish, is a terrifying thing to behold. They can grow up to two feet in length, but that’s not so weird. No the issue is the light they produce from a small lure that they use to bring prey to them. They flash this light and, when something gets too close, they snap into it with needle-like teeth so big that they don’t even fit inside their head. They’re able to curve the teeth and that makes it so they can actually shut their mouth. It’s something right out of the Ridley Scott Alien movies, but all the more horrifying because it’s real.
Every year, we find new species in the oceans, or we confirm the existence of something we suspected but never saw alive. That’s right here, on this world.
How can we expect to know what may or may not have evolved in the waters of other worlds?
Let’s cast our eyes deeper into the solar system, looking beyond Jupiter. Let’s go almost 696 million kilometers (over 432 million miles) farther and we’ll find ourselves within the orbit of Saturn. Now the planet Saturn itself is just as inhospitable to life as Jupiter. A gas giant, if Saturn does have a solid surface below the clouds, it’s under tremendous pressure and nothing we know of could survive there. There’s not a whole lot of water running around Saturn. It’s atmosphere is mostly hydrogen with just a little helium thrown around the clouds.
Every planet has some unique feature and Saturn is no exception. While many are familiar with Jupiter’s Great Red Spot, a storm stretching sometimes three times the diameter of the Earth across the face of the planet, Saturn too has a massive storm. The odd thing about it is its shape, that of a hexagon. Locked to Saturn’s north pole is a hexagonal storm system, each side approximately 13,800 km (8,600 miles) long. That makes each side of the storm larger than the diameter of the Earth.
Oh, and there are Saturn’s rings. I guess you could say those are a unique feature as well.
Actually the rings aren’t as unique as you may think. Jupiter has rings, so does Uranus. However neither of them have the span, the magnificent area, of the rings of Saturn. Each ring is a little different than the other rings. Some rings are basically snowballs, ranging in size from a few meters across to microscopic. Other rings are more rocky, and this ties into a hypothesis that says a portion of the rings are the remains of a moon that got a little too close and was torn apart by Saturn’s gravitational tides.
One ring, as it happens, is very special. The rings are named in sections. Some are simply lettered from A – G. Others, like Pallene Ring or the Phoebe Ring, are properly named. If we travel 180,000 km (111,847 miles) from the centre of Saturn, we hit the inner borders of the E ring. In this ring we find almost no large particles. Almost every bit of matter here is microscopic, but there’s a whole lot of it – enough to form a ring 300,000 km (186,411 miles) wide. It’s mostly ice with some ammonia and carbon dioxide and, in 2005, planetary scientists confirmed what they’d suspected for some time.
As Enceladus orbits Saturn, it’s spitting out a massive amount of water and ice in a process known as cryovolcanism. Unlike the volcanoes we know here on Earth, a cryovolvano doesn’t erupt lava or molten rock, but water and ice. Picture the world’s most famous geyser, Old Faithful in Yellowstone National Park. Now, make it bigger, much bigger. Then, put enough force beneath it to not only spray water into the air, but to blast it off the planet completely. That’ll give you some idea how a cryovolcano acts on Enceladus.
Now, when that water leaves Enceladus it’s exposed the extreme cold of space and it freezes quickly. The particles are so small, they freeze in microscopic droplets rather than larger drops and this is how the E Ring came to be. But let’s forget the ring for now because it’s not the interesting bit. No, the interesting piece is the ice and cryovolcanoes, because to have a cryovolcano, you need water.
The E Ring is huge, in fact it’s the widest ring in the entire ring system. When you’re talking that much material, you’re looking at a vast supply of water. Like Europa, Enceladus is thought to have a subsurface ocean, lying beneath the frozen and cracked surface. Many of the signs are there. The terrain, the very surface, appears even younger than Europa’s. The ice covering it appears to be new and that ice gives it a highly reflective characteristic.
Let’s talk about reflectivity for a second. Planetary astronomers call the characteristic reflection of a given surface its albedo. While there are different types of measurements of albedo, one of the most common and easy to understand is the Bond albedo, named after astronomer George Phillips Bond. The Bond albedo is simple because it measures all electromagnetic radiation reflected from a surface. This covers visible light, radio waves, microwaves, and the rest. The Bond albedo is a measurement from 0 to 1 with 0 being a totally black non-reflective surface and 1 being almost a perfectly reflective surface.
(As a side note, you can’t have a perfectly reflective surface given fiddly things like the laws of thermodynamics, but that’s something for another essay.)
To provide some comparison, the Earth’s Bond albedo is around 0.30. You can look at that number as a percentage and say that roughly 30% of the electromagnetic radiation hitting the Earth is reflected back into space. Our Moon, as bright as it is, only has a Bond albedo of 0.13. We have to remember that the reason the Moon is so bright to us is because we’re close to it. Hold a tiny bulb from a string of Christmas lights in front of your face. See how bright that light appears? Now, walk away from that light, say fifty feet. Doesn’t seem so bright, does it? So the Moon isn’t as bright as the Earth when viewed from space. Mars, which gleams as a beautiful red dot in the night sky, has a Bond albedo of 0.25 or 25%. At 0.25, it’s a fairly bright object and it’s no wonder it’s such a visible facet in our night sky.
Enceladus has a Bond albedo of 0.99.
Compared to Earth and Mars, and any other object in our solar system, Enceladus is like a mirror. The only reasons we can’t see it from Earth are its distance from us and its small size. With a surface that reflective, you are looking at a lot of new ice. That ice is coming from the cryovolcanoes and those cryovolcanoes must be powered by a subsurface ocean. While a subsurface ocean on Europa is only a well accepted theory, the existence of a subsurface ocean on Enceladus is literally scrawled across the sky. It’s there, we can’t see it directly, but we also can’t see the underground reservoir of water powering Old Faithful. We don’t need to see it, its existence is absolutely obvious.
So, a subsurface ocean on Enceladus. That makes it an incredible candidate for life in our solar system.
Now, in the words of many television infomercial hosts, “But wait! There’s more!”
An abundance of life on Earth lies in the oceans. That makes sense because there’s a lot of ocean when you compare sizes of the oceans versus the land, lakes, streams, rivers, and so on. If you were orbiting the planet and randomly flung a stone at the Earth, if we could assume it didn’t burn up passing through the atmosphere, the chances are really good that the stone will land in an ocean. Okay though, so what? There’s a lot of life in the oceans. What’s that have to do with Enceladus? Well, besides the life, and water, what else do you find an abundance of in the oceans?
That’s right, salt.
A great percentage of life on our planet not only needs water to live, but specifically they need saltwater. If you take a saltwater marine animal and dump it into a freshwater lake, you’ve sentenced it to death. The diversity of life in the freshwater systems pales in comparison to the diversity of life in the saltwater oceans. When it comes right down to the meat of the matter, saltwater is a pretty decent environment for life.
So isn’t it interesting that scientists have discovered a rather high concentration of salt in the icy materials jetting from the cryolcanoes? There’s a bit of it in the E Ring, but there’s also a lot of it on the surface of the moon, which only adds to that high albedo we talked about earlier. Finally, on one of its flybys, the Cassini probe discovered organic compounds in some of the dust spewed from the moon.
Step back, and take a look at all of that.
You have a body that’s warm enough to harbour liquid water. You’ve got a place where the water flows at least somewhat freely in a subsurface ocean protected from the harsh realms of space above it. You’ve got a place that not only has a subsurface ocean, but it’s a saltwater ocean much like the saltwater oceans of Earth. Beyond all of that, you’ve got a place that’s got a saltwater ocean with traces of organic compounds floating around in it.
You’ve got a major candidate for life beyond the bounds of Earth.
You’ve got Enceladus.