Oceans of Life

I love the Great Lakes, but I have a new crush- the ocean. I just returned from California and the Pacific. Over and over, like the ticking of an endless clock, waves crashed on the beach, bringing evidence of life from its depths and splaying them on the shore. The ocean seems timeless. But it wasn’t always here.

Early earth looked a lot different from the planet we know today. Scientists think that when earth first formed, there were no oceans. As the planet was forming, outgassing of the crust, along with constant meteor and comet bombardment, slowly built up the water vapor that condensed to form large bodies of water. These first oceans were not the blue beauties we are familiar with. We call earth the blue planet because of our azure skies and violet oceans, but when earth was young it had red skies and greenish-grey oceans. The thick early atmosphere was mostly carbon dioxide, and the water was a cloudy stew of water and other chemicals, with lots of salt from volcanic rock erosion and dissolving gasses from the air. Evidence suggests that this stew brought all the right ingredients together to create self-replicating matter, or life. The oldest life forms we know are found along the ancient ocean shores. Stromatolites are the fossil remnants of ancient communities of bacteria, and it seems that microbial life ruled the earth for most of its history, as far back as 3.5 billion years ago.

Now we find microbes in the violent heat and pressure of volcanic vents, and miles high in the harsh outer layers of our atmophere. Our bodies are crawling with them, and it is microbes that we search for as we send probes to other planets and moons.

The origin of microbes is not understood. Perhaps the earth supplied the right ingredients herself, or perhaps they flew in on a dirty comet from outer space. As we learn more about how life formed, we gain insight as to where to look for it in the solar system. And the evidence points to water.

We’re already crawling over the surface of Mars looking for signs of water. We find a lot of evidence for its existence, but as we drill into the rocks and look for fossils, none appear. We’ve also sent a probe to Saturn’s largest moon, Titan. The probe found no watery oceans or lakes in its quick descent and painless death on the moon’s cold, remote surface. Instead, it glimpsed rivers and streams of liquid hydrocarbons, which may be home to other, unfamiliar life forms, but nothing we can recognize.

Jupiter’s moon Europa also intrigues scientists, since it is completely enveloped in ice, has a thin surface layer of organic molecules, and may harbor an entire ocean of liquid water beneath the ice. Scientists are hard at work in Antarctica, perfecting tools that can drill through miles and miles of ice and submarines that can explore the depths. They hope to send a probe to Europa to drill beneath the ice and peer below this frozen shield. Though the mission is currently on hold at NASA, someday we will launch a vehicle to the oceans of Europa to see if they hold the promise of life. Even if they don’t, we will learn more about the incredible specialness of life here on our home planet.

Until next week, my friends, enjoy the view.