Earth, life, space: how we think about them



Though I’m no longer consulting with NASA’s planetary protection office, I still consider myself a member of the planetary protection community, and I’m paying attention to the neoliberal/libertarian drive to loosen up (eliminate, some argue) planetary protection requirements for so-called commercial space missions – robotic or human.

An ad hoc committee of the National Academies’ Space Studies Board is currently engaged in a review of planetary protection policy development processes, and I’m keeping an eye on this project as well as the discourse in the broader space community about planetary protection.

I’ve been reviewing some of the papers I’ve presented or published over the past 10 to 12 years that are relevant to planetary protection, and I’m going to post some of them on this blog.

What follows is a paper I presented at the 23d annual conferences of the International Association for Science, Technology, and Society (February 1, 2008, Baltimore MD). I’ve made some minimal changes to bring the paper up to date.

My intent here is to give you some food for thinking about whether and how the scientific search for evidence of extraterrestrial life has affected our conception of the terrestrial biosphere.

From my biased perspective, as a consultant to NASA’s astrobiology program, a scholar of communication, and someone who has worked in the space community for more than 30 years, I propose that the search for life beyond our planet has affected the way we think about our home planet. Can I prove it? No. Can I make a good case for this claim? I think so…. Can I provide a comprehensive explanation of how it has affected our conception of our biosphere? Probably not. But I will try to make my case as best I can….


Scientists have been studying the origins and evolution of life on Earth since the beginnings of what we call science.

Philosophers have been speculating about the possibility of other worlds and life elsewhere since the days of ancient Greece.

Scientists have been searching in earnest for evidence of extraterrestrial life since the beginning of the Space Age.

In the 21st century, the study of the origins and evolution of life on Earth, the origin and evolution of Earth itself and its sister planets, the origins and evolution of life in the universe and the origins and evolution of the universe itself are intricately intertwined.

Astrobiology, the study of the origin, evolution, distribution, and future of life in the universe, has made huge strides just in the past 10 years, due to space flight opportunities, new technology, and advances in molecular biology.

Let me quickly review the state of the art in the field of astrobiology….

We still do not know exactly how life began, or precisely where, or when, though theories about the origins of life continue to proliferate, and complexify.

We have learned that life as we know it – that is, carbon-based cellular life – can survive in virtually all terrestrial environmental extremes – nuclear radiation, permafrost, deep subsurface Earth, no sunlight…. Wherever humans or their technological counterparts have gone on Earth, they have found life.

We have learned that microbial life accounts for the majority of biomass on Earth and that most of this microbial biomass is likely beneath the surface of Earth.

Our spacecraft have flown by, orbited around, or landed on Mercury, Venus, Mars, Jupiter and several of its moons, Saturn and several of its moons, Neptune, and the dwarf planet Pluto and its moons…. And of course we’ve orbited a myriad of spacecraft around Earth to study the home planet. Comparative planetology is now a thriving field. We are now looking at Europa and Enceladus, in addition to Mars, as possible habitats for life….

Thanks to all of these advances, the prospects for finding extraterrestrial life – as we know it, or perhaps as we do not know it – look more promising by the day…

At the same time that research into the origin, evolution, and distribution of life is revealing that life is highly resilient, these same lines of research are helping to reveal how life and its environment are deeply interdependent.

Some key lines of research in this area – for example, the timing and mechanics of the rise of oxygen in the atmosphere of early Earth – have been sponsored by the element of NASA’s astrobiology program now called exobiology and evolutionary biology.

These findings are improving our understanding of life on Earth and prospects for life elsewhere, contributing to understanding of global climate history and evolution, and complexifying the further study of life.

This new understanding of the highly interdependent nature of life and its environment – their co-evolution, as it were – is undoubtedly changing the way we think about our biosphere and our place in it. And when I say “we” I mean both experts and non-experts…. This understanding has a role to play in defining our future on Earth and in space….

What follows is a brief and admittedly idiosyncratic review of the parallel and intersecting histories of the study of life on Earth, space exploration and the search for extraterrestrial life, and our understanding of our own biosphere.

The beginnings…

Questions of life – the origin and evolution of life, the fate of life on Earth, the possibility of life elsewhere – have driven space exploration from its beginnings. The search for evidence of extraterrestrial life is and always has been a primary focus of NASA’s planetary exploration program.

Planetary protection – the policy and practice of preventing terrestrial biological contamination of extraterrestrial environments and extraterrestrial biological contamination of Earth – has been a concern of the international science community since the start of the Space Age.

By 1967, spacefaring nations had reached agreement to regulate interplanetary contamination, as articulated in Article IX of the United Nations Outer Space Treaty. The treaty states that exploration of planetary bodies will be conducted “so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter….”

In 1959, NASA funded its first exobiology project, an instrument intended to detect evidence of biological activity on Mars. In 1960 NASA organized an Exobiology Program, to fund studies of the origin and evolution of life on Earth and the search for evidence of life beyond Earth.

Meanwhile, on the West Coast, in 1966 environmentalist Stewart Brand (founder and editor of the Whole Earth Catalog and CoEvolution Quarterly) began a public-awareness campaign aimed at prodding the space community to look at the whole Earth from space. “Why Haven’t We Seen a Photograph of the Whole Earth Yet?” Brand was asking, in hopes “that it would stimulate humanity’s interest in its mega-habitat” (Brand, 2007).

The first time U.S. astronauts saw and took pictures of “Earthrise” from space, capturing Earth and its Moon in a single frame from lunar orbit, was on the Apollo 8 mission in 1967. The common wisdom is that the advent of the human ability to see the Earth in its entirety from space helped to inspire Earth Day and the environmental movement.

On April 22, 1970, the first Earth Day was celebrated.

It was not until Apollo 17 in 1972 that NASA astronauts produced the now-iconic photo of the whole Earth from space, appearing alone in the void (Maher, 2004).

Environmental historian Neil Maher has argued that NASA’s 1967 “Earthrise” photo and its 1972 “Whole Earth” photo played key roles in two opposing cultural narratives. The “Earthrise” photo was one of “a long line of photographs enlisting nature to support American expansion at home and abroad…. By figuratively depicting [President John F.] Kennedy’s New Frontier in its sloping lunar surface, the Apollo 8 photograph helped extend America’s Manifest Destiny into the ultimate wilderness—outer space.” NASA’s 1972 “Whole Earth” photo “tells a different story,” replacing “the idea of the American frontier with a vision of non-American nature…an image of a more global natural environment” (ibid.).

Also in 1972, NASA launched Landsat I, the first element of a system of Earth observation satellites. The Landsat satellites, and other space-based earth-observing systems after it, have produced a more or less continuous view of the surface of Earth and its oceans over more than three decades.

We now take for granted the ability to see any place on Earth, any time, from space: fires in the Brazilian rainforest, flooding in south Asia, polar ice loss….

NASA’s Viking landers, launched to Mars in 1976, included three biology experiments designed to look for possible signs of life. Though the consensus is that those experiments did not find any evidence of biological activity on Mars, some scientists are still arguing over the meaning of the results. (This dispute persists in large part because scientists have been unable to agree on a precise definition of what life is (and is not).)

In 1977, Stewart Brand initiated a public debate, in CoEvolution Quarterly, about expanding human presence into space. Colonizing space “will be as momentous as the atomic bomb,” Brand declared. With space colonization, “our perspective is suddenly cosmic, our Earth tiny and precious, and our motives properly suspect…. If we can learn to successfully manage large complex ecosystems in the Space Colonies, that sophistication could help reverse our destructive practices on Earth. And if we fail…then we will have learned something as basic as Darwin about our biosphere – that we cannot manage it, that it manages us” (Brand, 1977, p. 72).

Also in 1977, in the world of science, biophysicist Carl Woese and colleagues announced in the Proceedings of the National Academy of Sciences that they had identified a new branch of life on Earth, called archaea. The New York Times reported on these findings, and history was made.

These scientists redrew the tree of life, depicting the evolution of life by genetic rather than structural relationships. The research that led to this momentous discovery was sponsored by NASA’s exobiology program.

In 1979, chemist James Lovelock unveiled his Gaia hypothesis, positing that Earth and all of its life are an integrated super-organism.

“My first thoughts about Gaia,” Lovelock says, came earlier in the 1970s “when I was working in [the] biosciences division of the [NASA] Jet Propulsion Laboratory, where we were concerned with the detection of life on other planets” (Lovelock, 1988, p. xvi) and working on plans for the Viking mission to Mars.

The Gaia hypothesis, according to Lovelock, “forces a planetary perspective. It is the health of the planet that matters, not…some…individual species” (p. xvii).

Also in 1979, Science magazine published a report of the discovery of life in hydrothermal vent systems of the Galapagos Rift (Corliss, et al, 1979). This discovery marked a major advance in scientific understanding of life. Not only was life thriving in environmental conditions considered inhospitable, but also this life depended on chemicals (chemosynthesis), not sunlight (photosynthesis), to survive.

The study of what we now call extremophilic life subsequently took off….

In the early 1980s, scientists working in the field of exobiology called on NASA to broaden its study of the evolution of complex biological systems on Earth to examine the evolution of complex life in the context of space. That is, NASA research into the origin and evolution of life should address “the effects of properties of the universe as a whole upon the evolutionary processes occurring on a planet’s surface” (Milne, et al, 1985, p. 2). NASA took heed.

In 1987, the World Commission on Environment and Development issued its now-famous report, “Our Common Future,” on sustainable development. “In the middle of the 20th century, we saw our planet from space for the first time,” the Commission noted in its report.
“Historians may eventually find that this vision had a greater impact on thought than did the Copernican revolution of the 16th century…. From space, we see a small and fragile ball dominated not by human activity and edifice but by a pattern of clouds, oceans, greenery, and soils. Humanity’s inability to fit its activities into that pattern is changing planetary systems, fundamentally. Many such changes are accompanied by life-threatening hazards. This new reality, from which there is no escape, must be recognized – and managed.” The Commission also noted in this report, “We have the power to reconcile human affairs with natural laws and to thrive in the process.”

Several years later, in his book Pale Blue Dot, Carl Sagan (1994) observed that while the human ability to see Earth from space has changed the way we think about our home planet, “the connection between exploring other worlds and protecting this one is most evident in the study of Earth’s climate and the burgeoning threat to that climate that our technology now poses. Other worlds provide vital insights about what dumb things not to do on Earth” (p. 221) – for example, atmospheric ozone depletion, greenhouse warming, and the generation of nuclear winter.

In 1996, NASA’s exobiology program was superceded and encompassed by a new astrobiology program, dedicated to the study of the origin, evolution, distribution and future of life in the universe (Dick and Strick, 2004)….

To reiterate, astrobiology is the study of the origin, evolution, distribution, and future of life in the universe. This multidisciplinary field now encompasses the search for habitable environments in our Solar System and habitable planets outside our Solar System, the search for evidence of prebiotic chemistry and life on Mars and other bodies in our Solar System, laboratory and field research into the origins and early evolution of life on Earth, and studies of the potential for life to adapt to challenges on Earth and in space.

NASA’s Astrobiology Program addresses three fundamental questions: How does life begin and evolve? Is there life beyond Earth and, if so, how can we detect it? What is the future of life on Earth and in the universe? In striving to answer these questions and improve understanding of biological, planetary, and cosmic phenomena and relationships among them, experts in astronomy and astrophysics, Earth and planetary sciences, microbiol­ogy and evolutionary biology, cosmochemistry, and other relevant disciplines are participating in astrobiology research. In its search for evidence of extraterrestrial life, the Astrobiology Program is funding a wide array of research in molecular ecology and molecular evolution, geared “towards understanding the origins of life and the evolutionary history of organisms on this planet” (Sogin, 1999).

Among “other relevant disciplines,” the social sciences and humanities have an important but as-yet-undeveloped role to play, especially in considering the future of life on Earth and elsewhere.


In light of all these social and scientific developments that I have just described, and many others that I have not described, I conclude that the search for extraterrestrial life has most certainly affected our conception of the biosphere, the way we think about our home planet and our place on (or in) it. Expert and non-expert understanding of life, at the macro and the micro level, is changing, rapidly…..

It would be difficult – though interesting and potentially fruitful – to document exactly how the search for extraterrestrial life has changed the way we think about the biosphere. I cannot do that right now. But I will consider some ways in which the search has altered our perspective.

Considering the biosphere at the microscopic scale, we now know that life teems kilometers beneath the surface of Earth, around deep-sea hydrothermal vents, inside Antarctic rocks and at the bottom of perpetually ice-covered Antarctic lakes, in highly acidic hot springs and radioactive water. Life like us thrives by photosynthesis. Another sort of life on Earth thrives by chemosynthesis. The idea of life in other planetary environments barely requires a leap of imagination these days….

We have recently come to understand that microbial life, extremophilic or otherwise, dominates our biosphere. As astrobiologists have put it, “For more than 3.5 billion years, microbes of untold diversity have dominated every corner of our biosphere” (Sogin and Jennings, 2003).

Microbes play a key role “in geochemical cycling, biodegradation, and the protection of entire ecosystems from environmental insult…they control global utilization of nitrogen through nitrogen fixation, nitrification, and nitrate reduction; and they drive the bulk of carbon, sulfur, iron, and manganese biogeochemical cycles.” Most important to us, “the continued survival of later evolving multicellular plants and animals is completely dependent upon interactions with microorganisms” (ibid.)….

Considering the biosphere at the planetary scale, we now know that the more we explore extraterrestrial environments, the more we learn about how different they are from Earth. And at the same time we find that they are similar, too.

We routinely look at pictures of Earth and other planets taken from space these days and remark upon their resemblances and their differences. We know that planets and planetary environments evolve. We cannot help but think – even believe – that some of these extraterrestrial environments have life….

I have mentioned the role of planetary protection policy in space exploration. Building on the concept of planetary protection and extending our constructions of “nature” and “wilderness” into the solar system, some astrobiologists have advocated the creation of a “planetary park system” to preserve and protect pristine extraterrestrial environments of scientific importance or “natural beauty” from environmental degradation or contamination by terrestrial exploration missions.

Planetary parks would “extend the reasons for practical protection policies beyond the utilitarian protection of scientific resources emphasized by planetary protection, into other utilitarian and intrinsic value arguments” (Cockell and Horneck, 2004, 2006).

The idea of “astroenvironmentalism” has been explored outside the science community as well. The principles of astroenvironmentalism, as detailed by one environmental writer, include “considering space and the celestrial bodies pristine wildernesses that need to be protected,” requiring environmental impact statements for space missions, treating planetary bodies “as wildernesses that need to be protected,” and creating ethical guidelines for protecting life elsewhere (Miller, 2001)….

So our constructions of “environment” and “nature” in what Steven Yearley (2008) calls “advanced modernity” are thus being extended from Earth into space. From an environmentalist perspective, this is a good thing.

Alternatively, the search for evidence of extraterrestrial life is affecting our conception of the terrestrial biosphere in a different, conflicting way. There is a trend in the space community, energized in the Reagan era and reinvigorated during the George W. Bush years, toward viewing the solar system as an environment to exploit, as we have with our own planetary environment. From this “dominionist” or “manifest destiny” perspective, our home planet, and our home solar system, are seen as resources here for us to use as we like.

These two opposing perspectives on the place of humans in space are reflective of two parallel and conflicting cultural narratives of space exploration (Billings, 2007): outer space as a sort of supermarket of resources, open to exploitation by whoever gets there first; and outer space as a pristine wilderness to be studied and appreciated but left unaltered.

Rhetorical critic Janice Hocker Rushing speculated that the post-Apollo focus of space exploration on the search for evidence of extraterrestrial life is a product of a widespread understanding that humankind exists in a universe, not only on planet Earth. A contemporary narrative of space exploration might better reflect this understanding by telling a story of “a spiritual humbling of self” rather than “an imperialistic grabbing of territory.” Space is too big to be conquered, as Rushing pointed out….

Cultural studies scholar Constance Penley has also examined cultural narratives of space exploration. While noting that “the WASP space cowboy version of spaceflight” has persisted from the Apollo era into the present, Penley has observed that NASA “is still the most popular point of reference for utopian ideas of collective progress.” In the popular imagination, “NASA continues to represent…perseverance, cooperation, creativity and vision,” and these meanings embedded in the cultural narrative of spaceflight “can still be mobilized to rejuvenate the near-moribund idea of a future toward which dedicated people…could work together for the common good”….

The more we look, the more we find that life is everywhere on, and in, Earth. The more we look, the more we find that the basic ingredients for life as we know it are everywhere, not only throughout our solar system but throughout interstellar space. We have also found that much of life on Earth – perhaps the majority of it – is “weird” extremophilic microbial life, adapted to niche environments that humans and their multicellular relatives could not tolerate.

While astrobiologists are identifying biosignatures for detecting extraterrestrial life as we know it – carbon-based, cellular life – they have also begun the task of developing a set of biosignatures to use in searching for signs of life as we do not know it – extraterrestrial weird life – life that does not need water as a solvent, life that is not made of carbon-based compounds (Space Studies Board, 2007).

To wrap up, let me restate my initial question in a somewhat different form….

Without the search for extraterrestrial life, would we have come to understand, as we now have, how life and environment continually shape each other?

My answer is, “I don’t think so.” Though I cannot prove my claim, let me offer the views of a few other experts to back it up.

In the mid-1970s, anthropologist Ashley Montagu told a NASA-sponsored symposium on the subject of “life beyond Earth and the mind of man” that people “are no longer humane beings, but sick persons – a sickness induced by the worship of false values….” Montagu recommended preparing for what he considered to be the eventual discovery of extraterrestrial life “by becoming what you ought to be, by realizing your evolutionary destiny, which is to live as if to live and to love were one” (Berendzen, 1975, p. 26).

In a similar vein, planetary scientist and natural philosopher David Grinspoon (2004) has observed, “We can conceive of a truly intelligent, sustainable communicating society. But we don’t know if we can become one. So we search the skies for confirmation of a hopeful image of ourselves” (p. 414).

Can, does, the search for extraterrestrial life help us humans to figure out how to live together?

Stewart Brand (2007) continues to prod us to think about Earth from the perspective of space. In the scientific journal Nature, he asserted that to better understand our home planet, we must integrate data gathered by Earth-observing satellites with genetic data gathered by microbiologists – a merger of the macro with the micro. “Metagenomics is giving us detailed access to the genes and gene communities of bacteria and archaea,” he wrote.

“A unifying body of data, ideas, models and images of the whole-Earth system could inspire the public and may shift scientific thinking. In studying the energy dynamics of the Earth–Sun system while learning how our microbial partners manage to keep this planet comfortably terraformed for life, we would begin to step up to the full meaning of Earth stewardship.”

Environmentalist Bill McKibben (2007) has considered how space exploration has broadened his perspective on our home planet. “This may come as less of a shock to others, but it’s my own recent discovery: we live on a planet,” he wrote in Orion magazine.

NASA’s Apollo images of Earth from space, he said, “seemed designed to shock us into seeing that the world we knew was finite, that we had been born onto a lovely oasis…we should protect at all costs.”

In McKibben’s opinion, however, this view “didn’t take…we’ve done more to damage the planet in the decades since that picture appeared than in all of human history before that.”

From a different perspective, political scientist Walter McDougall (2007) has considered how space exploration and the search for life elsewhere has affected our views of life on Earth and come to the same conclusion as McKibben. That is, we are not getting the message.

“The greatest icon bequeathed by space technology” to humankind thus far, McDougall claims, is the Apollo 8 “Earthrise” photo. “It has become a cliche to observe how Earthrise inspired environmentalists since it vividly depicted our biosphere as finite and fragile….”

Just as important as this new perspective on our biosphere, he says, “was the urgent if obvious revelation that the natural, holistic earth seen from space is free of political, racial, and religious boundaries. The sum of those two perceptions must be a Spaceship Earth mentality transcending mundane considerations of geopolitics and geoeconomics.”

But “no such transcendence has begun to occur,” McDougall concludes. “Even after the end of the Cold War, so often blamed for perverting the dream, astronautics has worked no metamorphosis, no paradigm shift, in human behavior. Conceptions of extraterrestrial worlds as our property to exploit and as pristine environments to protect are in competition for a central role in U.S. space policy.”

Twenty years ago, environmental philosopher Eugene Hargrove (1986) predicted, “It is not unlikely that the environmental movement…will split into warring camps over the issue of resources exploitation of the Solar System…some environmentalists will decide that we should exploit [these] resources…to the full in order to bring resource exploitation on Earth as close to an end as reasonably possible; others will conclude that such resource exploitation is simply a continuation of improper environmental policies long pursued on this planet” (pp. xi-xii).

Current discourse about our future in space addresses this important ideological issue, but, regrettably, the environmental community is not engaged in the discussion. Nor is the STS community, to my knowledge.

In the Handbook of Science and Technology Studies, Steven Yearley notes that environmental studies are critical to STS because they provide “key insights into the status of ‘the natural’ in advanced modernity” (p. 921)….

He concludes that science and technology studies have has become the primary scholarly means of “understanding ‘knowing nature’ in conditions of advanced modernity” (p. 940).

In this presidential election year, when space policy issues are in the public eye, scholars of science, technology, and society can contribute to the public discourse on these issues – and perhaps even build a needed bridge between environmentalists and the space community – by expanding the boundaries of their conceptions of “environment” and “nature” to encompass outer space, where humans are venturing more frequently and more invasively.

Can our vision of a human future in space become a vision of humanity’s peaceful co-existence on Spaceship Earth and the need to work together to preserve life here and look for life out there?

In conclusion, I would argue that developing new perspectives on our home planet and the place of, and for, life on it is perhaps the only sound rationale for continuing a government-funded space exploration program in the early 21st century. The search for extraterrestrial life can help humans to feel at home in the universe, fostering a sense of belonging. As it did in “Star Trek: Voyager,” the search can encourage us to care about our home.

I encourage the STS community to consider how the search for evidence of extraterrestrial life is affecting our understanding of biospheres (terrestrial and extraterrestrial) and how this understanding might help to shape space exploration policy and plans.

Which cultural narrative will it be? The human conquest and exploitation of extraterrestrial environments, at the expense of extraterrestrial life if need be? Or careful robotic exploration, preserving pristine extraterrestrial environments for their own sake, with or without life?

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