“In certain circles, astrobiology has become a resounding but meaningless catchword in the competition for grant money.” — Nature, August 9.

Like its predecessor “exobiology,” the recently coined field of “astrobiology” is accused of being a science without a subject. The curiosity of a well-funded research project without evidence of its reason for being (i.e., life beyond earth) led to an interesting debate in Nature on August 9: “Astrobiology: Frontier or Fiction”.

Astrobiology, the study of life in the universe, is sometimes criticized as being a fashionable label that simply rebrands already existing research fields. Its practitioners, however, argue that the discipline provides a broad framework for developing a better understanding of the frontiers of biology. In biologist and a planetary scientist offer their views.

Critique by a Biologist
Antonio Lazcano, the biologist, was gently brutal in his assessment of the scientific status of astrobiology, killing it with faint praise. First, he traced its origins:

Stimulated by controversies that arose over the evidence for extraterrestrial life in the Martian meteorite ALH 81004 in the mid-1990s, NASA reorganized its programs on exobiology and planetary science as part of an attempt to integrate its research on life sciences into its space-exploration efforts. Thus was born astrobiology, an all-encompassing effort that was expanded to include the study of extremophiles, the occurrence of planets and their habitability beyond our Solar System, and research on the origin and evolution of life on Earth, among other disciplines. But can a funding programme be transformed into a new science?

His faint praise was to acknowledge that the program created jobs, “endorsed the teaching of evolutionary biology,” and generated much open publication. Along with it came “specialized journals and scientific societies, university courses, graduate programs and books, as well as by a handful of centers and networks of varying scope and uneven academic standards in countries other than the United States.”
But then, Lazcano worried that many of these efforts “tend to place far too much weight on a handful of loose analogies between extremophilic microbes and the potential habitability of other worlds in our Solar System.” If life exists in extreme environments on Earth, it does not follow logically that it forms in extreme environments elsewhere. Arguments from analogy cannot form the basis for claims about other worlds. The flap over arsenic-based life exhibits a tendency to “extrapolate to other parts of the universe the ability of microbes to adapt to extreme environments” here. He added this zinger: efforts to do this “may be due more to the struggle for funding than to the desire to study habitable planets.” Looking at the logic of the situation produced this blunt statement

In the absence of unambiguous proof for its existence, almost nothing can be said about extraterrestrial life about which the opposite is not also true. The scarcity of evidence gives considerable latitude, and, in certain circles, astrobiology has become a resounding but meaningless catchword in the competition for grant money.

Lazcano is willing to agree that the search for life beyond the earth is a legitimate scientific question, but in practice, from what he’s seen, its practitioners don’t keep a healthy distance from science fiction and “from the theological musings that somewhat surprisingly find their way into astrobiology meetings.” This lack of rigor, combined with the broad-brush category astrobiology has become, is disturbing. In his conclusion, all faint praise vanished:

Depending on who you speak to, astrobiology seems to include everything from the chemical composition of the interstellar medium to the origin and evolution of intelligence, society and technology — as if the Universe is following an inevitable upward linear path leading from the Big Bang to the appearance of life and civilizations capable of communication.
Neither the formation of planets nor the origin of life is seen today as the result of inscrutable events; rather, they are considered as natural outcomes of evolutionary processes. However, this does not mean that such outcomes are inevitable, and it is still to be shown that life exists — or has existed — in places other than Earth. The lack of evidence should not inhibit us in the slightest, but unless we are bound by the highest academic standards and critical attitudes, astrobiological discussions will become nothing more than empty speculation laced with a formidable disregard for scientific plausibility.

Defense by a Planetary Scientist
What was the comeback of Kevin Hand, the planetary scientist? It’s not clear he read Lazcano’s piece before publishing his; but if he did, he paid it little attention. His arguments consisted largely of the very analogies that Lazcano criticized.
For one, Hand analogized from the other three great fields of science — physics, chemistry, and geology — that biology must also apply beyond the earth. He analogized further that, since theoretical entities assume scientific status in physics (like the Higgs boson), extraterrestrial life deserves recognition as a scientific hypothesis.
Hand quoted a paper that defined astrobiology as “the application of geobiological principles to the study of planets and moons beyond the Earth” — committing the very extrapolation Lazcano warned about. Going on from there, he dabbled in discussions about methane on Mars, implying astrobiology is needed to sort out the geological from the biological causes, and the Mars Science Laboratory rover, implying that our knowledge of methane will help interpret what the rover finds. All this begs the question whether astrobiology as a new field of science (with its own funding demands) is required to answer such questions. Astronomy, chemistry, and biology seem poised to offer their own answers without help from a composite concoction like astrobiology.
Hand was not done with arguments from analogy: “The analogy in chemistry would be as if, after creating the first periodic table in the 1860s, Mendeleev and others had decided not to search for more elements, even though the gaps in the table provided a guide for where to look.” But Mendeleev had many elements, with well-defined gaps in his table. Astrobiology knows of only one instance of life in the universe; it’s not a fair analogy.
Then he made a logical leap, claiming, “Life on Earth serves as a guide for identifying potentially habitable environments elsewhere.” That’s simply not true. Much of the discussion about life beyond Earth revolves around questions of whether it is totally different from life as we know it. Finding habitable environments elsewhere, furthermore, is not necessarily a part of astrobiology. A million habitable worlds could be lifeless.
His last arguments made no pretense of being empirical. He speculated about whether life might be found on Europa or other planets or moons: “If funding permits, within the next few decades we will know the answer to whether or not life exists elsewhere in our Solar System.” But hope alone cannot justify spending public money. That’s essentially all he had to offer: “It’s time for biology’s great experiment. It’s time to learn whether we live in a biological Universe or one in which life on Earth is a singularity.”
Interesting as those questions are philosophically or theologically, they do not substantiate astrobiology’s claim to scientific status. They do not bind astrobiology to the highest scientific standards. They do not overcome Lazcano’s criticism of astrobiology as “empty speculation laced with a formidable disregard for scientific plausibility.”
Contrasting Astrobiology with Intelligent Design as Science
Intelligent design theory does not attempt to answer the question whether life exists beyond earth. It could handle either outcome. It is concerned with known causes adequate to produce certain effects wherever they are found. Unlike astrobiology, ID does not assume evolution as a cause. The cause required to produce the effects seen in life, like irreducible complexity, complex specified information (CSI) and functional purpose, is intelligence. Evolution — an unguided, purposeless, stochastic phenomenon — is arguably not a cause at all.
Intelligent design is not an extrapolation. As a cause, intelligence is known to produce CSI and functional machines. It is an inference to the best explanation, not an extrapolation into the unknown. If you find a language in code that conveys meaning, you know that intelligence produced it, even if you can’t read it (as Egyptian hieroglyphics remained mysterious before the Rosetta Stone).
Intelligent design is not an argument from analogy. Analogies compare unlike things. A bacterial flagellum is not analogous to an outboard motor; it is an outboard motor. A molecular machine that employs energy to produce work is just as much a machine as an artificial machine. The genome is not analogous to a code; it is a code.
Intelligent design, furthermore, is not a science in search of a subject. ID is already in wide use in archaeology, forensics and cryptography, among other fields. The very same inference to intelligence is assumed by SETI researchers, even though most of them are evolutionists.
For these reasons, intelligent design has a much stronger claim to scientific status than astrobiology. Unfortunately, in our particular political context at the moment, ID is far too politically incorrect to garner a spot at the federal funding trough.