An Expedition to Mars (as played by a Central American volcano)

by Mary Martialay on January 20, 2015

Rensselaer Professor Karyn Rogers wrote this guest post while cruising at 30,000 feet aboard a Boeing 737 on a flight from Albany to Managua, Nicaragua. After landing, hopefully without delay or lost luggage, she will travel to the colonial city of Leon, jumping off point for the expedition to the Cerro Negro volcano (pictured above) which she describes below.

My name is Karyn Rogers and I am a professor in Earth & Environmental Sciences (E&ES) in the School of Science at Rensselaer, and also a member of the New York Center for Astrobiology. Depending on the day, and the expedition, I am a geochemist or geomicrobiologist or astrobiologist. On this expedition, I am all three! Our research team includes a geochemist and a planetary geologist from the University of Colorado, a graduate student from the University of Colorado, and our very own Diana Parios, a graduate student with me in E&ES.

We are heading to Nicaragua to spend a week studying and collecting samples from a young volcano named Cerro Negro, which lies just northeast of the City of Leon. Cerro Negro is a relatively young volcano, about 150 years, and still quite active, with the last major eruption occurring in 1999/2000. It is also a relatively unique volcano in that it looks a lot like Mars!

Okay, to the untrained eye, it doesn’t look like Mars at all (perhaps it’s all the surrounding vegetation that’s confusing!), but once we look into the details — like the types of rocks and minerals we find on this mountain — it has quite a striking resemblance to Mars. For example, if we look at the composition of the Cerro Negro basalts (the rocks that are formed during a volcanic eruption), we find a composition very similar to Martian basalts, including a very high iron content.

Cerro Negro interior. Courtesy of Brian M. HynekWhile the outer slopes of the volcano are generally covered in chunks of this basalt, the interior of the volcano looks quite different (as pictured at left). Here we find a jumble of rocks that are stained yellow, red, orange and green, and hot steam vents that remind us all that this volcano is very active. There is little water here, but what little there is can be quite interesting. In many locations the steam that condenses on these rocks has a pH close to zero. As this very hot and very acidic steam pours through the volcanic basalts, these rocks are altered to form new suites of minerals and these minerals look a lot like the minerals that the NASA Rovers Spirit and Opportunity have found on Mars! All of this is why we go to Cerro Negro. In fact, I have been studying this volcano since 2008 and this is my fourth expedition to this fascinating and dynamic mountain.

You might be wondering what we can learn by looking at Nicaraguan rocks and look a lot like Martian rocks. Well, part of my research is to understand what conditions, on Earth and on other planets, are necessary for life to exist. I use modern environments on Earth to figure out what might limit life on Earth (like high temperature, or high pressure, or low pH). But when it comes to figuring out where to look for life on other planets, like Mars, it’s a good idea to have some idea of what kinds of environments that could exist on Mars might also support life. One way to do this is to find places on Earth that most resemble Mars (Mars analogs), and to study whether or not they can support life. The kind of life I look for is microbial life — small, single-celled organisms that have very simple lifestyles. These primitive organisms are most closely related to Earth’s earliest organisms and scientists think that, if life ever emerged on Mars, they would have been the most likely early organisms there as well.

So, for the past several years I have been searching for microbial communities on Cerro Negro and trying to understand what they’re doing there and how they survive this harsh environment. So far, we have had some pretty interesting results. We have found that there are very steep temperature gradients around these steam vents, where the temperature changes from about 80°C to over 300°C with an inch or two of the surface. However, there are also more habitable locations where temperatures range from 40-75°C.

We don’t find microbes everywhere we look, but we do find, them – that’s the exciting news – and what we find is pretty interesting!  So far, we have found groups of microbes that work together to make a living in this harsh environment.  Some of these microbes are phototrophs; like tiny plants, they use energy from sunlight to make organic matter (for instance, more cells).  There are also chemotrophs, organisms that use chemicals in the local environment for energy (humans do that by eating food and gaining energy by oxidizing that food to carbon dioxide with oxygen in the atmosphere). Some of the chemotrophs at Cerro Negro use oxygen to process their food, but others do not, instead using forms of sulfur and iron to take the organic matter that is made by the phototrophs and turn it into carbon dioxide.

Together these groups of microbes make a living in an environment that looks pretty harsh to you and me. This gives us an idea of how a microbial community might survive in similar circumstances on Mars. Furthermore, some of the microbes that we find at Cerro Negro are encrusted in minerals that form very distinct spheroidal shapes that are then preserved in the rocks even after the microbes die. This helps us to know what we might look for in Martian rocks as evidence for past life there.

On this trip, I am trying to better understand exactly how these microbes are surviving. During past expeditions, we have identified these microbes using their DNA, but they look quite a bit different (sort of how I am only genetically very distantly related to my 23rd cousin) from a lot of the microbes we already know about. On this trip my team and I are trying to get some of these microbes to grow in the laboratory, so that we can better understand what they are doing and how they are surviving the conditions of an acidic fumarole that could have once and could still exist on Mars. I will be back in a week with an update and hopefully some new microbes to tell you about.

If this sort of topic is fascinating to you, check out my classes on the Origins of Life (ASTR 4510) and Geobiology (ERTH 2960). Meanwhile, wish us luck and stay tuned!