by Nola Taylor Redd for Astrobiology Magazine
Moffett Field CA (SPX) Oct 19, 2012
The Mars Science Laboratory Curiosity rover has 10 science instruments, and each will be used in the coming weeks and months to help characterize the environment of Mars and determine if the planet ever had the potential for life. The Sample Analysis at Mars (SAM) instrument is actually a combination of three individual instruments that will investigate the chemistry of the Martian surface. Roughly the size of a microwave oven, SAM will analyze samples taken by the robotic arm, looking for organic and inorganic compounds.
NASA's Jen Eigenbrode is one of the scientists working with SAM. Presently following the cycle of a Martian day, or Sol, Astrobiology caught up with her while she was starting her day off at 1 pm Earth time.
What does it feel like living on Mars time?
What kind of science do you generally do?
I am an organic biogeochemist. I study organic molecules that are trapped in rocks, sediments, and ice. My research addressed techniques for recovering molecules from the materials that host them, as well as their sources and preservation over geological time. Often, at least on Earth, the organic molecules in rocks, sediments, and ice are a record of microbial ecology. On Mars, we don't know what the record is of yet.
What is it then that you do specifically with MSL?
I'm also a participating scientist studying the effect of high-energy proton radiation on sediments with organic materials. The question I seek to address is, how will cosmic radiation affect the search for organic molecules at Gale Crater?
Let me use a hypothetical situation to explain this research. Suppose sediment deposited at Gale Crater contained organic materials, possibly from life, maybe from a geological process. Over geological time, those sediments were buried and then re-exposed at the Martian surface as a rock outcrop.
Then along comes Curiosity. Curiosity drills five centimeters into the sedimentary at rock, collects a sample, and uses SAM to analyze it. The discovery of martian organic materials regardless of its chemical composition would suggest the prerequisites for Mars to develop a biosphere were complete. The lack of an organic detection would raise more questions.
In both cases, to fully interpret the observation we need to know if cosmic radiation bombarding the surface of the expose rock has destroyed or significantly altered the original organic materials in that rock. We have no Earth analog for the radiation environment on Mars, and so the best that we can do is experimental studies.
What I am going to do then is take an artificial analog of materials that we suspect Curiosity might come across at Gale Crater, expose the analog sediments to high levels of radiation, and see what happens to organic molecules. The results will inform SAM scientists on how to interpret observations. I have several SAM and MSL operational roles in the mission activity.
Some of this entails working in groups to daily decide what type of science observations we want to achieve. Some of it is more along the lines of being ready to assess the data that comes down from satellites and check it to make sure we got the data that we were expecting.
I am also involved in working with the other scientists on getting ourselves as prepared as possible for interpreting the first sets of data that's come down from some of the SAM experiments.
There's a lot of work that we can do in the lab, a lot of analysis that we can do of earlier data that we collected when SAM was still here on Earth. We're evaluating all of that. We're on the edge of our seats waiting for data and we want to be as fully prepared as possible to be able to review that data and interpret what we get from Mars when we analyze our first solid sample. Hopefully, we'll find some martian organics in it.
The MSL mission has been in the works for over ten years. I joined NASA five years ago, and since then I have been actively involved in SAM at various levels. SAM is the most unique and complex instrument suite I have ever come across. If you were to compare a conventional, commercial set of instruments to SAM, it would take up my entire laboratory. We managed to squeeze all that instrumentation into something the size of a large microwave oven, built to withstand launch and landing and the environment of Mars.
It doesn't behave the same way that an instrument in my lab would behave. We need to understand all that to make sure that we can really make sense of the results that we get back. I am continuously working to reconcile the differences between doing instrument analyses on Mars as opposed to in my comfortable, climate-controlled lab. Thinking through how to do science on Mars with SAM is a welcoming challenge.
How could your work help to answer astrobiology questions?
So, if life were to be on another planet, it would most likely be in microbial form. Mars is close to Earth. It's easy to get to and seems to have an early history similar to Earth's. It is currently the best place for us to look for evidence of extraterrestrial life.
What astrobiologists have done, as a community, is try to pin down the requirements of all life, especially of microbial life. One of the basic ones is water. All of life needs water. It is part of cellular structure, which helps to form and provide environmental conditions that are moderate to extreme, and it is a medium for transporting nutrients around and getting rid of waste products. We now know that Mars has a "water history".
Water has actively shaped the surface of the planet for a very long time. Energy sources enable life to do things. We know there are energy sources, because the rocks themselves provide that kind of energy. So does sunlight. Most environments have an energy source already available. The other requirement is carbon.
Organisms need organic molecules to build their biological structures, transfer energy, and conduct biochemical reactions. Thus it would seem that the crux the habitability puzzle on Mars is figuring out where the organic carbon is.
Even if Mars never had life, it should have organic molecules, whether from geological processes, or meteorites raining down on the surface. They should be there. We think Gale Crater has the right rocks to preserve them. Yet we haven't looked closely enough to actually detect them.
That will change with Curiosity. In taking this full circle, if we were to find organic molecules in the rocks at Gale Crater, then all of a sudden we will come to the realization that the ancient environment of Gale Crater could have supported life. That's a pretty big deal, because right now we don't know of any other place beyond Earth that has ever been capable of doing so.
It sounds like a baby step in the astrobiology big picture, but it actually is a fundamental step forward in addressing "Is there life out there beyond Earth?" If we don't find organic molecules at Gale Crater, then it begs the question of why not.
We will need to understand, given the chemistry of the rocks, the nature of the modern surface environment, and what we think about the surface environment over the last several tens of millions of years since the rock had been exposed, what could have happened to those organic molecules?
Could they have been lost? For the first time in history, we have a mobile astrobiology laboratory to explore the red planet and an interdisciplinary team of 400+ scientists studying its observations. There is no doubt that we will learn a great deal about the habitability potential of Mars and why Mars evolved so differently from Earth.
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