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Table of Contents
Cover Story
Earth Sciences
Life Sciences
Northwest Explorer

Looking For Life In All The Weird Places

Books By Washington State Professors Explore Limits And Possibilities For Life In The Universe

Life as We Do Not Know It: The NASA search for (and synthesis of) alien life
by Peter Ward
288 pp., Viking, 2005

Life in the Universe: Expectations and Constraints
by Dirk Schulze-Makuch and Louis N. Irwin
172 pp., Springer, 2006 (2nd ed.)

Depending on how you look at it, the field of astrobiology is either expanding or contracting rapidly. Astrobiology, the study of life in the universe, has scored several major successes in recent months, benefiting from a continuing win-streak of missions to Mars, Venus, the Saturnian system, and even back from a comet with samples enclosed. These missions have yielded an extraterrestrial treasure trove of information about conditions on planetary bodies in our solar system and of their chances for supporting life.

Yet simultaneously, astrobiology has taken hits in the earth-bound realm of budget-wrangling. This March, NASA announced that it will be postponing or canceling many planned projects in order to meet President Bush's targets for manned space flights. The New York Times reported (March 2, 2006) that the cuts will come to $3 billion over the next five years, even as NASA's overall spending grows. The sudden shelving of high-profile projects like a sample-return mission to Mars and an exploration under the ice of Jupiter's moon Europa has been especially hard on astrobiologists—especially after repeated assurances that such projects would not be sacrificed to fuel the president's directives for human spaceflight.

So, as budgets tighten and the universe of possibilities for research constricts, many rocket-scientist minds are at work trying to figure out ways to focus the search for life beyond Earth on the best bets for success.

The multibillion dollar questions: Does life exist beyond Earth exist, and if so, how do we find it?

Two recent books by professors in Washington state address these issues. One book is a wide-ranging account of the science for a popular audience; the other is a slim and academic (but handily organized) textbook. Both books seek to expand the view of what we might look for and to focus the discussion of where we are most likely to find life.

Peter Ward's Life As We Do Not Know It is the more wide-ranging and layman-friendly read. Ward, a paleontologist by training, is a professor of biology and earth and space sciences, and an adjunct professor of astronomy at the University of Washington. He is a principal investigator for the NASA Astrobiology Institute, and the author of twelve other science books for a popular audience.

While he has won awards and commendations for the accessibility of his earlier books, the one that brought Ward the most notoriety is Rare Earth (NWS&T, Winter 2000), which he coauthored with fellow UW professor Donald Brownlee. In Rare Earth, the authors argued that simple forms of life may be more common in the universe than we've previously thought, but at the same time it is highly unlikely there are places other than Earth that would allow life to evolve into complex, intelligent forms. The book became a bestseller for its highly readable explanation of this theory; but it was also criticized by those who believe we will one day communicate with sentient beings beyond our atmosphere.

Life As We Do Now Know It picks up where Rare Earth left off. It presents findings from the fast-moving field of astrobiology that have advanced the science in just the past few years. It also addresses an acknowledged gap from the earlier book—essentially, that it only discussed the possibilities for finding life like that on Earth: life with carbon-based chemistry, water-filled cells, and DNA. "[I]t is surely possible that there must be a multitude of types of life differing in their most fundamental properties of chemistry and metabolism,” writes Ward. "Such life indeed might be life as we do not know it.” (p. xxiii).

Ward responds to the criticism of his earlier book with vigor. He devotes several chapters to exploring definitions of life and eventually comes up with a new classification scheme for it— a new tree of life that puts DNA life out on a new limb (with a brand new level of taxonomy) and life that doesn't need on another. On this new branch of life he hangs viruses, which have always been problematic for life-definers because they are unable to reproduce without hosts.

Ward doesn't shrink from controversial claims, and seems even to enjoy the role of the heretic. But rearranging the tree of life and adding viruses to it is just a starting point. From here, Ward goes on to what we calls a "rational look at what alien life might be like” (p. x). He explores possibilities for alternative chemistries and genetic codes of "life as we do not know it,” explores proposed ways for how life might evolve, and introduces readers to some fascinating efforts (perhaps already successful) at creating synthetic life.

Ward's book really blasts off, however, with the tour of the galaxy in the final chapters. In these, he assesses the possibilities for life on various planets, moons, and orbiting bodies, and discusses how we might explore them. He tells of recent exciting findings with the passion of an insider, and campaigns for future explorations. He clearly has his favorites, most notably Saturn's moon Titan, where the European Space Agency's Huygens probe landed successfully in 2005. Ward doesn't oppose human exploration, and even puts in a plug for one day sending a scientist (preferably a biochemist) to Titan and another (preferably a paleontologist) to Mars. It's obvious that he would go himself, if only he could.

Ward's treatment of Titan demonstrates his vivid, reader-friendly writing: "We descend into the palisade-like ring wall of a large impact crater on Titan's surface. With the tiny sun now below the horizon, the thick, ruddy smog that is Titan's atmosphere darkens into dim magenta and then loses all color” (p. 217).

One major strength of Ward's book is its accessibility. In his introduction, he takes us to the famous Star Wars bar, only to argue that the diverse, highly evolved renegades found there are not nearly so likely as modest microbes. At another point in the book, he takes us on recreated ALVIN dive with scientists who may have found "aliens” on earth (at least life as we did not know it) at hydrothermal vents under the sea (pp. 1-5). Ward contrasts synthetic life creation to Dr. Frankenstein's work and presents other spot-on metaphors throughout.

In one particularly helpful passage (chapter 4), Ward compares how life might have began to his own impatient efforts in the kitchen, and presents a "recipe book” of theories. Also here is what seems to be a sly dig at religion: "Sometimes I think it simpler just to consider all this cooking as some miracle taking place out of my sight. Much easier that way. But the chaos in the kitchen afterward, the mess left behind, puts the lie to that little fable. . . . There are no miracles in cooking.” (p. 89)

There are places where Ward's writing is not so engaging. These come mostly when he is listing theories or ideas, or when his musings become brainstorming sessions on the page. In this wide-ranging book, some sections are also more complex than others. When he introduces his new taxonomy, Ward says he's "making it at one and the same time a science book for the public and a science book for the scientists” (p. 47)—but the details of this section tilt it toward the expert readers.

You will find few flowery sentences in Life in the Universe, though

it's obvious the authors don't lack a sense of creativity and fun. After all, the book's dedication (complete with ultrasound image) is to "an embryonic individual of a species on a water-rich planet in an otherwise unremarkable solar system at an outlying part of the galaxy in an unexceptional part of the universe” (the then-unborn child of the first author, p. ix).

Except for this brief indulgence, the authors may have intentionally kept humor in check. They note in their preface an upsurge in the number of books written about life in the universe, and note (respectfully) that "scientific depth has often been sacrificed in favor of the laudable goal of engaging a broad audience” (p. v). Instead, they opt for a critical and contained exploration of what astrobiologists should look for and how they should look for it.

To do this, the authors draw upon backgrounds in multiple disciplines, as is appropriate in the melting-pot field of astrobiology. The first author of the book, Dirk Schulze-Makuch, is currently a professor of geology at Washington State University (WSU) in Pullman. He and his coauthor, Louis Irwin, a biologist, published the first edition of the book in 2003 when both taught at the University of Texas at El Paso (Irwin continues to teach there).

What results is a slim, tightly structured tour of life in the universe. Like Ward's book, it begins by expanding what we might think of as "life” and progresses by looking at life's needs and limits—listed as: energy sources, chemical building blocks, solvents for biological reactions, and habitats. Each chapter is succinct and summarized clearly at the end. Also like Ward, the authors share the basic argument that "life occurs redundantly in the universe”, but that in ways that "strain conventional thinking about the fundamental nature of living systems.”

The authors of Life in the Universe have their own picks for places in the universe likely to have habitats for life. As mentioned in passing by Ward, one of Irwin and Schulze-Makuch's areas of interest is the theory that there might be conditions for life in the atmosphere of Venus. There is more detail about how one might detect such life. However, while these authors sometimes stick their heads into the clouds, they think the greater probability is that life will be found on the ground, or better still, underground where the harsh conditions of most planets would be mitigated.

One of the strengths of Life in the Universe is the authors' attention to assessing the likelihood of the ideas they propose. They acknowledge that theirs is a speculative field. And what it may lack in flair, Life in the Universe makes up for in clarity and brevity. Of the two books, this would be the more appropriate to present in a time-crunched syllabus. In fact, the authors test-drove this volume in a graduate seminar.

That said, the textbook format, tables, and diagrams this book contains shouldn't make it scary. There is jargon, but the authors have kept it to a minimum. A science-savvy reader interested in astrobiology should find almost all of the text accessible. And it helps that chapters are brief, and explained again at the end.

One of the drawbacks to the authors' critical, textbook approach is that the book ends abruptly. Look to Ward's book instead for closing chapters on the implications of exploring (and possibly contaminating) other planets and for direct advocacy of the next steps we should take. Also, one might have hoped for more updates about missions that have happened since the first edition of Life in the Universe. But the fact may be that the field is moving too fast.

In the end, both of these books are well-suited for their different purposes. While tackling the problem in different ways, both challenge the boundaries of what we consider life and indicate the most plausible places to find it outside Earth. Both serve as good summaries of a science that will be naturally speculative until people find real evidence of alien life. But this speculation about the possibilities of life for our universe is also what makes the field so much fun.

Ben Raker is a Seattle-based writer and editor who studied science writing at the University of Washington.

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