Jack Farmer's scientific career is clearly on track these days. He's the director and principal investigator of Arizona State University's astrobiology program, funded by NASA. He's also chair of the NASA Astrobiology Institute's Mars Focus Group, heading NASA's efforts to select landing sites with biological potential for the 2003 Twin Mars Exploration Rovers. As a leading exopaleontologist, Farmer serves on a half-dozen committees that oversee NASA's program of robotic exploration of the solar system. But if he seems to be settling down these days, settling down might be little more than another new adventure.

Moving Early and Often

There was a time when geologist Farmer bounced from place to place, position to position. After getting his Ph.D., Farmer worked for 5 years as a museum scientist at the University of California (UC), Davis, collecting and maintaining the geology department's teaching and research collections. For those five summers he taught a six-week field and lab-based course in marine paleoecology at Bodega Marine Laboratory in northern California--a course that drew students from all over the world. It was this course that consolidated his interest in modern analog studies as a tool for interpreting the past. He left that job to spend 5 years as a senior petroleum geologist for Exxon, hunting for oil and gas in offshore areas of southern California. Another change brought him to the University of California, Los Angeles (UCLA), where for the next 5 years he taught a heavy load in earth science, paleontology, oceanography, and sedimentology as Visiting and Adjunct Professor. Then came yet another move to the NASA Ames Research Center in the heart of California's Silicon Valley, where he worked as a National Research Council (NRC) Senior Fellow.

"I'm a generalist," said Farmer in a recent telephone interview. "In college, the thing I didn't fully grasp about geology was how broad a field it is. Geology has provided me the latitude to explore. I've spent much of my career exploring that breadth of geology and doing lots of different things, all with the goal of understanding Earth history."

Jack Farmer.

Photo: Seth Shostak/SETI

Farmer attributes his wanderlust to a keen sense of curiosity. "I think part of it is I'm an explorer. I was 6 or 7 years old when I got started collecting rocks. By 10 or 12, I had a huge collection. Then, in high school I got interested in biology. In college geochemistry and volcanology were early interests, and I did my senior thesis in that field. Then I swept across the field of geology again to interface with the life sciences. I did my Ph.D. in paleobiology."

Putting It All Together Takes Time

As a graduate student in paleobiology at UC Davis, Farmer had developed an interest in studying the paleoecology and preservation potential of fossils, something that would lie largely dormant over the next decade while he tried his hand at other things. While at UCLA, however, Farmer returned to this his first love, doing research on stromatolite-forming microbial communities. Here he developed a keen interest in the early evolutionary history of multicellular animal life. Toward that end he pursued studies of small (meiofaunal) grazing animals living within microbial mats and documented the earliest appearance of animal and trace (so-called Ediacaran) fossils in late Precambrian sediments in NE Norway.

At UCLA, Farmer developed the contacts that would eventually help move his career along when he participated in the creation of an award-winning textbook, The Proterozoic Biosphere: A Multidisciplinary Study (1992), edited by UCLA professor J. William Schopf. Collaboration on the book brought Farmer together with an international group of experts on Earth's early biosphere, creating a informal network of colleagues that includes many of the researchers that Farmer continues to work with today.

One of these colleagues, geochemist David Des Marais, suggested that Farmer apply for an NRC Senior Fellowship at Ames; he did so in 1991. At Ames, Farmer studied microbial life in the hot springs at Yellowstone National Park,a project he began in 1989 while still at UCLA. In many hot springs, minerals like silica, iron oxide, and carbonate precipitate out of the water, sometimes trapping microbes like insects in amber, creating "instant" microfossils. Through this work he became committed to understanding the factors that control long-term preservation.

Farmer compared the modern fossilization process happening in the Yellowstone springs with the microfossil record of ancient hot spring sites like the 350-million-year old deposits in NE Queensland, Australia which he described with colleague Malcolm Walter.

"In the early '90s, I worked with hot springs," Farmer says. "Now, I'm working with low temperature carbonate springs in eastern California and central Mexico. In all these springs, there's a common thread: the rapid precipitation of chemicals from springs mediating the formation of chemical sediments. These are natural laboratories which reveal how biosignatures are captured and conserved in rocks in different environmental settings. The ultimate goal is take this information and apply it to interpreting the deep record on our planet. The other purpose is to take this information and use them to explore Mars."

From Paleontology to Exopaleontology

At Ames, Farmer turned back to his grad-school interests in paleobiology and sedimentology and, combining them with his interest in microbial communities, found his research niche: the study of microbial biosediments and their relation to early biosphere evolution. Working with some of the colleagues he'd met on the textbook project, his next step was to apply this information to the creation of a whole new field: the study of ancient environments on planets, such as Mars, that resemble Earth.

After the 1978 Viking missions showed the early limitations of NASA's search for life on Mars, Farmer's work provided NASA with a new direction. Applying to Mars the methods of paleontology that proved successful on Earth, Farmer developed the science of exopaleontology (a term he coined) to the study of early conditions on Mars and other earthlike worlds.

There are significant risks to this approach. Even in 1991, very little was known about the Red Planet. More study might still reveal that Mars was fundamentally different from Earth in its development. If it existed at all, life might have developed in locations completely different from the places where Farmer and his colleagues are looking, wasting NASA's time and limited resources. But, if they're going to look, they have to look somewhere.

Farmer's hunch was that early life on Mars, if it existed at all, followed a path similar to that of life on Earth and thus could be found in the same places and detected by the same means that paleontologists use to discover Earth fossils. Among the best places to find Martian microfossils would likely be at the sites of mineralizing springs, ancient evaporite deposits, and soil hardpans.

"We think there were a lot of hot spring environments on Mars," says Farmer, "and large lake basins where evaporites may have formed. On Earth, there's hardly a place in these kind of environments where biology is not expressing itself. Given that these springs on Earth are teeming with life, my hunch is that it's a good place to begin looking for ancient biosignatures on Mars."

In 1994 Farmer, now a Civil Servant and Research Scientist at Ames, helped NASA outline a strategy for locating fossil biosignatures on Mars. The strategy called for a series of robotic missions to perform three tasks: 1) identify likely sites from orbiting spacecraft to map surface mineralogy; 2) send landers to the best sites to locate aqueously deposited sedimentary rocks; and 3) mount surface missions to target and sample the most likely deposits at these sites and return them to Earth for in-depth laboratory study.

Farmer's experience with Exxon, which involved a variety of imaging and remote sensing techniques to locate geological structures favorable for the accumulation of petroleum, also served him well in working with NASA mission planners and technologists developing the instruments to be carried into Mars orbit by the next generation spacecraft. Farmer helped craft the original measurement requirements that would drive instrument development and, with his students and post docs, carried out terrestrial analog studies to help reveal what could be learned in support of exopaleontology.

Farmer helped select the landing site for Mars Pathfinder and thinks that the Mars Surveyor and Mars Odyssey spacecraft now in orbit have begun the job of meeting the first-stage requirements of finding potential ancient hydrothermal systems--for example, the Mars hematite site at Terra Meridiani. "On earth, coarse-grained ("specular") hematite only forms in the presence of abundant water," says Farmer.

In 2003, two Mars Exploration Rovers will pursue the second stage of the search strategy by sending probes to two promising sites on the surface. As the Chair of the Mars Exploration Payload Assessment Group (MEPAG), the primary community based mission planning group, Farmer will help refine the 2009 mission payload. Later this summer MEPAG will also produce recommendations regarding mission pathways beyond 2009 and the timing of a first sample return.

Still Taking Chances

Farmer's success in creating an exopaleontological approach to the study of life on Mars is due in no small part to his willingness to take chances and try new things. His decision in 1998 to move from NASA's Ames Research Center to a tenured position in the geology department at Arizona State University is another example of a willingness to take on new challenges. At Arizona State, Farmer is in charge of the new astrobiology program, with new responsibilities that add administration and teaching to his research workload for NASA.

Says Farmer, "We have close to 85 people in ASU's program now, about half of whom are students, we maintain the books for 24 separate accounts and must constantly update our program website- our primary tool for public engagement. Trying to keep everybody happy and the research moving is a challenge, but I have a great group of people working with me to make sure this happens. "Since I came to ASU four years ago, it's taken a while to get my research program off the ground, That's been rolling for a couple of years now. There is an ongoing obligation to my students to help guide them toward excellence. I strive to keep them motivated and on track. It adds to the diversity of things I do every day."