Lonely Planets

by David Grinspoon

  than any bet in Atlantic City, since we don’t really know what kind of

  game we’re playing. We have to base our strategy on educated guesses.

  We want to go and look anyway because, well, how could we not? This

  argument is not sufficient to sway congressional committees, or the

  White House Office of Management and Budget. It doesn’t do to say,

  “Okay, Madam Senator, we admit we are stabbing in the dark, but if

  you give us a lot of money, we’ll certainly learn much of value, and who

  knows, we might make the discovery of the millennium.” Our missions

  to other planets are in part scientific experiments, but in large part they

  are just poking around the neighborhood to see what we dig up. So we

  ask for money for exploration and seek to justify it as science.

  Now that exo has morphed into astro, is biology here to stay as a linchpin of our space exploration plans? If life continues, like quicksil-ver, to elude our grasping hands, will we stay on task? By casting our

  lot in with astrobiology we are expressing faith in its longevity.

  Astrobiology is hot now, but historically both scientific interest and

  government support are cyclical. It remains to be seen whether we can

  commit for the long haul. But for our society this is good practice at

  thinking on long timescales, which as a survival skill is as essential as

  learning to think globally.

  W H A T A B O U T T H E R O C K S ?

  And what of the little worms who started all this astrobiology fuss, the

  “microfossils” in the Mars rock? In the eyes of most of the community,

  they have been demoted to strange mineral deposits that were probably

  not made by living organisms.

  In the seventeenth century Johannes Kepler described oceans and an

  atmosphere on the Moon. The excitement generated by Kepler’s reports

  helped spur scientific interest in a plurality of worlds, and that interest

  retained momentum long after better telescopes and more objective

  observers revealed the Moon to be a dry, battered ball of rock.

  Similarly, in the late twentieth century, astrobiology was given its

  biggest impetus by a discovery most practitioners now regard as highly

  250

  L o n e l y P l a n e t s

  dubious. As with the Viking biology results two decades earlier, the

  confusion underscores the difficulty of identifying, or agreeing on, signs

  of life.

  Personally I’m not sure. I don’t think we can entirely rule out the

  possibility of some biological products in the Martian rocks, but I am

  highly skeptical. One problem is that we know nothing of where on

  Mars these rocks came from, since we received them as random shrap-

  nel sprayed by some long-forgotten impact. Assuming we can find

  more rocks with similar features on Mars, it will be much easier to

  interpret them when we can examine the environments where they

  formed.

  There are, in fact, living and fossilized terrestrial bacteria that look

  very much like these things, with the same segmented, elongated

  shapes. However, the Martian “worms” are incredibly tiny compared

  to any organisms we know of on Earth. They are about one hundred

  nanometers long and ten to twenty nanometers wide. (A nanometer is a

  billionth of a meter.) The smallest bacteria on Earth are hundreds of

  times larger than this. Life-forms using our type of chemistry probably

  cannot fit into a package so small. You need to have a container large

  enough to hold the genetic material that describes how to make the

  container.

  Today, the general attitude in our field is surprisingly scornful of the

  Martian fossils, even among many who are enjoying the funding and

  interest in astrobiology that they sparked. Scientists agree that we need

  more data from Mars. It is commonly said that we won’t be able to

  answer the question definitively until we return carefully chosen sam-

  ples from Mars and analyze them in our labs on Earth. Even this may

  be optimistic. It is quite likely that once we do return the first Martian

  samples, the answer about the “fossils” will still be “maybe.”*

  The scientists who claimed that they had found fossils in ALH84001

  did us all a big favor, and I don’t just mean the increased funding for

  research in astrobiology. They got us all thinking. When we asked our-

  selves, “Could this be real?” we realized that there is no reason why we

  shouldn’t find ancient fossils on Mars, even if there are none in these

  *Returning a small sample from Mars is turning out to be much more difficult, technologically, than we once thought. When I joined SSES in 1998, the central goal of our Mars program was to return Martian samples to Earth by the year 2005. Then it got pushed back to 2014, and now 2020 is looking more realistic . . .

  Astrobiology

  251

  particular rocks. And, the reasoning continues, since the extremophiles

  on Earth show us that life can adapt to a surprising range of conditions,

  couldn’t this ancient life have somehow adapted to modern Martian

  conditions?

  Biological or not, those nanoscale wormies in that little four-pound

  Mars rock made NASA and the planetary community turn and face our

  true purpose. By exploring space we are embracing life, not running

  away from it.

  Is It Science Yet?

  16

  LONDON—An elaborate, 155-year-old hoax was

  revealed Monday, when the Royal Astronomical

  Society confessed that the planet Neptune does not

  Image unavailable for

  exist. “It appears to have begun in 1846, when

  electronic edition

  Johann Galle needed a big discovery to give his

  career a jump start, so he fabricated this new planet,”

  said Royal Astronomical Society president N. O. Weiss.

  “Ever since, every astronomer who’s wanted some attention

  has come up with some new report on ‘Neptune’ and made up some rubbish

  to support it. I swear, we meant to come clean eventually, but the whole

  thing just kind of snowballed.”

  — The Onion

  W E I R D S C I E N C E

  We scientists recoil against alien stories and beliefs that ignore stan-

  dards of evidence and common sense.* Yet, extraterrestrial life is

  among the most difficult of subjects to approach scientifically.

  Astrobiology is not just another science. It has sometimes been derided

  as a “science without a subject,” or even more harshly as a pseudo-

  science. I disagree. But, to recap, here are four ways in which it is weird

  science:

  1. We ourselves are part of the phenomenon we seek to study. Can

  a camera photograph its own lens?

  2. We can’t say what it is exactly that we are looking for on other

  planets, but we think we’ll know it when we see it.

  *Admittedly, sometimes science rules against common sense.

  Is It Science Yet?

  253

  3. We rely entirely on a single example—life on Earth. Could you

  imagine trying to develop a science of botany if you were locked in

  a room with only one seed? This does not make for “good science”

  the way we usually think of it. In medicine, for example, we are

  suspicious o
f studies with small numbers of test subjects.

  4. We are blatantly biased by an overwhelming desire to find cer-

  tain answers. Life good. Dead universe bad. Science, we have been

  taught, is supposed to be neutral, like Switzerland. We’re not sup-

  posed to take sides or rig the game. Yet, when it comes to life in

  the universe, we’ve unabashedly forsaken our neutrality. We can’t

  hide our love away. We want life.

  Science demands “well-posed” research questions that we can frame

  as specific hypotheses for us to test. We can’t go to Mars and do an

  experiment designed to “search for life, whatever that might be.”* But

  we also can’t just sit here on Earth and fret over our philosophical

  conundrums while Mars stares down at us licking its chops, guarding

  its precious secrets. So, we make educated guesses about which aspects

  of Earth life will be universal. We go to Mars and search for water, for

  organic molecules, for biogenic gases, for microbial mats. We look for

  signs that on Earth would point to life. We employ widely accepted, but

  unproven, criteria for inhabited planets. To “do good science” we have

  to pretend we know the answers to the big questions “What is life?”

  and “What kinds of planets are living?” This is fine, as long as we don’t

  forget that we are still following hunches.

  Astrobiology is intellectually unrestrained—some would even say

  flaky—compared to other fields. It is not too hard to come up with a

  conjecture about the origin or early evolution of life, or the possibility

  of life in some alternative planetary environment, and get a publication

  (and a newspaper story). Peer review still applies, but our filters are

  somewhat loosened, as there is a wide acknowledgment that outside-

  the-box thinking must be encouraged, up to a point, since we don’t

  really know the shape or size of the box. Inevitably, some junk slips

  through. When reading astrobiology papers, you have to set your bull-

  *Although simple cameras come the closest to such “open to anything” experiments, which was why Sagan was so keen on using the Viking lander cameras to look for macrofauna.

  254

  L o n e l y P l a n e t s

  shit detector on a slightly higher setting than you would when reading

  in an older, more established field.

  Lately, I’ve been thinking of astrobiology as a resurgent branch of

  natural philosophy. Calling it this may help us remain mindful of the

  limitations and assumptions necessary to do our science and the larger

  questions that we sometimes sweep under the rug.

  N A T U R A L P H I L O S O P H Y

  The fence we’ve built between science and philosophy is a recent con-

  struction. Up until about 150 years ago, the study of the natural world

  was not called science, but natural philosophy. There were no “scien-

  tists,” only natural philosophers. Many famous philosophers, including

  René Descartes and Immanuel Kant, had important physical insights

  that contributed to the foundations of science. Likewise, none of our

  classical Western scientific heroes—(e.g. Galileo, Darwin, Newton, and

  Kepler)—called themselves scientists.* They were philosophers with a

  particular interest in understanding nature. Starting with Galileo, some

  philosophers developed an experimental method of establishing truths.

  We who inherited this approach call ourselves scientists, and we gener-

  ally forget that what we assume to be the ground rules—the obvious,

  unquestionable truths about nature—were part of a new and radical

  philosophy just a few hundred years ago.

  Bertrand Russell said that “science is what you know and philoso-

  phy is what you don’t know.” Indeed, science grows at philosophy’s

  expense, continually siphoning off the known to sprout new disciplines.

  For example, the study of consciousness and the mind used to be part

  of philosophy, but now it’s psychology and neuroscience. Studying the

  heavens and pondering other worlds was once something that philoso-

  phers did. When we started to learn something definite, these musings

  became the science of astronomy. Only those areas in which we have no

  solid answers at all are left as a sticky residue for philosophers to roll

  around in.

  Along with the switch to “science” came a narrowing of scope. Science

  *None of them would today be considered “skeptics” either: Newton was obsessed with alchemy. Kepler practiced numerology and based his conclusions about extraterrestrial life on mystical principles. Herschel was convinced, for metaphysical reasons, that there was life on the Sun, Moon, and planets and devoted his astronomical career to finding evidence for it. Darwin was a creationist.

  Is It Science Yet?

  255

  became professionalized. It became a full-time day job and splintered into

  a few, and then many, separate fields and specialties. Natural philoso-

  phers did not carve up the universe like that, and they didn’t separate sci-

  ence from questions about the limits of science. In becoming scientists

  we’ve accepted an invisible framework. We don’t worry about the rules

  about how to do science, because these seem obvious, beyond question.

  Paradoxically, none of us can say exactly what these rules are. The history

  and philosophy of science are not part of a scientific education. Rather,

  scientists learn the stories and rules through an intuitive cultural assimila-

  tion, the way a child picks up the rules of social interaction.

  Philosophers of science have competing ideas about what “the scien-

  tific method” is, or even whether there is one.* They argue about the

  way science really works, but they all agree that no theory about sci-

  ence is remotely scientific. Meanwhile, working scientists are far too

  busy doing science to worry about what it is.

  Scientists ask, what can we know of nature? To this, natural philoso-

  phers added, how can we know this and what can’t we know? Science,

  as it has grown in confidence, has lost the ability, or at least the desire,

  to question its own authority. Before science became Science, think-

  ers kept these questions closer in mind. A new natural philosophy

  approach would rejoin science with philosophy of science as a common

  area of inquiry.

  In some ways our present science cannot completely handle the ques-

  tion of extraterrestrial life. In this field, more than any other, we must

  keep our grand ignorance of the ways of the universe constantly in

  mind and be open to anything. Yet, this kind of approach flies in the

  face of what is usually considered to be good science, because science

  requires that we make specific predictions to test hypotheses. The odd

  status of astrobiology in the suite of sciences can, I think, be under-

  stood by realizing that it is not yet science, exactly, but still natural

  philosophy.

  An awareness of the limits of science is especially important when we

  skirt close to its edges. For an honest consideration of the questions

  raised in this field, we must bravely sail beyond the edge of the scientif-

  *Historically, these ideas have included the empiricism (letting nature speak for itself) of Galileo, the
experimental, inductive approach of Francis Bacon, the pure reason of Kant, the provisional truths and falsification of Karl Popper, and the “normal science” and revolutionary paradigm shifts of Thomas Kuhn.

  256

  L o n e l y P l a n e t s

  ically mapped world back into the realm of natural philosophy where,

  in addition to chipping away at some relevant, well-posed scientific

  questions, we should constantly ask ourselves, “Why do we believe

  what we believe?” What is the interplay between common sense, evi-

  dence, intuition, and faith that forms our beliefs about life in the

  universe?

  None of this is meant as a put-down of astrobiology. I think natural

  philosophy is a fine thing indeed and may be what science needs now.

  By helping rejoin the splintered communities of science, and rubbing

  our noses in the limits of science, astrobiology can help us to rediscover

  the study of nature as a whole.

  Another problem plaguing science these days is a sometimes deserved

  reputation for arrogance. But modesty is called for when facing the

  huge unknowns in studying alien life. A natural philosophy approach

  could also infuse our quest with a much needed dose of humility, which

  can only help science.

  During the Enlightenment, science grew out of natural philosophy

  and took on a life of its own. In an unconstrained field like astrobiol-

  ogy, where our ignorance so outweighs our knowledge that we are not

  even sure how to ask the right questions, we can benefit from hearken-

  ing back to the earlier approach. Our innocence in the ways of the uni-

  verse demands that we be natural philosophers again.

  O U T O F T H E N E U T R A L Z O N E

  We have been taught that science is largely value-free except for a sense

  of integrity to the truth. We are supposed to dispassionately interrogate

  nature and accept the answers, whether we like them or not. Yet, in the

  past, natural philosophers often mixed their spirituality, ethics, and val-

  ues in with their science.

  Our neutral stance is not just a cop-out. It arises from an attempt to

  maintain a high standard of objectivity—a commitment to letting

  nature be the judge. Undeniably, it is methodologically dangerous to

  want a certain answer too badly. When hunting wabbits on Mars we

  have to be vewwy, vewwy careful not to scare them up out of nowhere.