From the sea floor to Mars and beyond - diving deep helps us search for life elsewhere in the solar system

Imagine yourself at the bottom of the ocean able to withstand more than 200 times the pressure you’re experiencing right now, near freezing temperatures, and of course being able to see in the dark. 

Now imagine that you’re not just anywhere on the sea floor. Imagine youself staring at a towering rock structure glittering with fools gold and spewing what looks like black smoke into the surrounding seawater. You are now staring at one of the thousands of hydrothermal vent chimneys that are found in particular locations on the ocean floor.

Some say life on Earth originated at hydrothermal vents. Others speculate that geological features like hydrothermal vents likely exist elsewhere in our solar system on places like Jupiter’s volcanically active moon Europa. For these reasons hydrothermal vents here on earth are often used as analogue environments to help astrobiologists figure out how best to look for extraterrestrial life. 

So why are these vents so important, and why should we attempt to better understand inner space life in order to better look for life in outer space?

As you all know, we depend on the sun’s energy to power photosynthesis which enables plants and other organisms to produce the bioligical material (or biomass) that is the foundation of most food chains in most ecosystems on Earth. Not all ecosystems though...

At hydrothermal vents something very different happens, and it is this something that we think might be happening on other worlds that are too far away from the sun or covered in ice and therefore unable to be able to use the sun's energy to generate biomass. By any definition these vent chimneys represent extreme environments... extreme pressures, temperatures up to 400°C, near complete darkness, and it is in these extreme environments that microbes harness energy from chemicals spewing from the earth, rather than energy from the sun in a process called chemosynthesis to create living material.

This process, of chemosynthesis, could -in theory- occur and form the basis of food chains and ecosystems anywhere there is volcanic activity and water.  In hydrothermal vents on Earth microbes garner energy from gasses like methane, sulfide, sulfate, or hydrogen.

One major reason that hydrothermal vents are my favorite thing to think about and study is that the process of doing so is inherently interdisciplinary. 

We need geologists to tell us how seawater gets entrained in the seafloor, how it interacts chemically with the crustal rock and transforms in to hot, metal-rich hydrothermal fluids, and how it is then responsible for the awe inspiring structures I had you visualize a minute ago. 

We need chemists and bioenergetic modelers to look at the composition of these fluids and predict what chemical reactions are favorable that might provide energy life. 

And we need biologists (like me!) to look for life in and on the walls of these chimneys and tell us who is there and what they are actually doing. 

We also need engineers to help us build instruments and vehicles that can access these environments and collect the samples we need.

So, by studying how microbes eek out a living in one of the most extreme environments on Earth, by asking questions about how specifically they generate biomass, what metabolisms they carry out, and what are the factors that limit life in these extreme enviromnents, we may actually be learning how alien microbes are surviving or even thriving on distant worlds.


A New Age in Ocean Exploration

Technology like Google Maps and Google Earth make it seem like the entire world is at our finger tips. So, you might not believe me when I tell you that Earth is largely unexplored, but its true. The vast majority of the sea floor has never been seen by human beings. This is in stark contrast to Mars and the moon for which we have far more detailed maps because of satellite technology that is unable to "see" through water. However, emerging technology is making this distant deep sea world much more accessible. I'll start with a story to show you what I'm talking about... 

Live streaming video of my experiment at the bottom of the Pacific

Live streaming video of my experiment at the bottom of the Pacific

Just the other day I was sitting in my office on the east coast, interacting with a research expedition that was at sea studying hydrothermal vents in the eastern pacific.  They were visiting a site where I had deployed an experiment two years before, which I was really hoping they would be able to collect with the robotic submersible (ROV) ROPOS they were working with. I got an email from my collaborator at sea that morning saying that this was the day! I went to the website where the expedition was live streaming both cruise updates and video footage from the submersible on the sea floor (connected to the ship via cables and then sent out to the Internet through satellite connections) in real time. I was able to keep an eye on what the sub was doing all day long. When the time came and I saw (with much relief) that the team had located my experiment, I noticed lots of microbial growth on my samplers and wondered if they might be clogged, which would have changed the experimental conditions. I called in to a satellite phone, and while I was looking at my experiments I was able to request that the team on board make specific temperature measurements that would tell me how my samplers were functioning. It was a short phone call because folks at sea are very busy and satellite phone time is expensive, but I was able to listen to the audio from the ship's control room that intermittently accompanied video from the sea floor when the folks on board had something to narrate, and I could hear the temperature measurements. I grabbed my notebook from the cruise two years before and was able to see that the temperature had decreased significantly in the two years since my experiment. The cool thing is that I would not have known I needed those measurements if I had not had eyes on the sea floor, but there I was in my office on land far from my study site.

This summer there were 5 different expeditions that I know of in different locations on different ships that were streaming live video from sea. You watched archived video footage from the group that collected my samplers here, but they won't be live streaming again until next summer.  When I first went to sea to do research in the summer of 2010 I was aware of any ships live streaming from the sea floor, so technology is definitely changing how we study this largely unexplored world. However, streaming video from sea is just the beginning. The same expedition that collected my samplers was deploying cameras and seismic sensors that will soon be connected to a network of fiber optic cables that have been laid in order to transmit power to specific sites of interest on the seafloor and relay data back, to land in real time, from the depths. So, soon I'll be able to watch live video from my site even when a research ship is nowhere near. These first sensors in certain locations are just the beginning. It's hard to imagine how deep sea research will change when we can plug instruments into a power source on the sea floor and no longer rely on batteries with limited lifespan to power our instruments, when we can have eyes on our sites year round as opposed to the sampling season when ships can safely access our sites, when we can gather a continuous stream of data rather than a few snapshots when we are lucky enough to get out to sea, and perhaps most importantly when all that data is publicly available to scientists who might not be able to get out to sea, to teachers for use in classrooms, and to curious folks everywhere.

We are entering a new age in deep sea exploration, and I feel very lucky to be a part of it.