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1
Introduction
ASTROBIOLOGY AT NASA
In its current usage, the term “astrobiology” is variously defined as the study of the origin, evolution, distribution, and future of life in the universe; the study of life as a planetary phenomenon; the study of the living universe; or the origin and co-evolution of life and habitable environments.1-3 The term was apparently coined in the 1940s4 and was used periodically in the 1950s.5 In about 1960 “astrobiology” appears to have been supplanted by the more restricted term “exobiology” and then independently reinvented in 1995 by Wesley Huntress, NASA’s then-associate administrator for space science.6
The history of NASA’s involvement in astrobiology and its modern precursor, exobiology, can be divided into three periods. The first lasted from the late 1950s to the time of the Viking Mars program in 1976. During this period, NASA’s Office of Life Sciences devoted many resources to the study of the origins and evolution of life on Earth and elsewhere in the universe. The second period began after the Viking spacecraft failed to unambiguously detect evidence of life on Mars. This disappointment reduced NASA’s eagerness to fund follow-on missions to Mars or other major activities relating to the search for life beyond Earth. In 1996, exobiology experienced revitalization in the aftermath of an announcement claiming the discovery of evidence of past life in the martian meteorite ALH 84001, and the subject of exobiology began its transformation into the current-day field of astrobiology. The revitalization and transformation mark the third historical period.
Beginnings to Viking
NASA’s involvement in exo/astrobiology stems from repercussions generated by an international conference focused on studying the origins of life that took place in August 1957 in Moscow. The location of the conference, in conjunction with the Cold War-driven political climate of the time, spread fears among U.S. officials that the Soviet Union had discovered the secret behind the origins of life. Joshua Lederberg, a young Nobel Prize-winning biologist, had recently begun pondering the notion of life on other worlds and was able to use the fears generated by the 1957 conference to persuade the newly formed NASA to devote resources to studying the origin of life. Lederberg argued that NASA would need to understand the origins of life on Earth in order to plan the search for extraterrestrial life. He coined the term “exobiology” to describe studies relating to the origins of life on Earth and the development of instruments and methods to search for signs of life in the cosmos.7
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In 1960, NASA created the Office of Life Sciences. One function of this office was to award grants for exobiology research. This research included studying life-detection techniques, learning how to prevent forward and back contamination of planetary environments by spacecraft, and studying the origins of life.
After the founding of NASA’s Office of Life Sciences, exobiology continued to grow. Many scientists who were unable to achieve funding through agencies, such as the National Science Foundation (NSF) and the National Institutes of Health (NIH), that required that their work fit into a rigidly defined scientific discipline were successfully courted by NASA and encouraged to apply for exobiology grants.
NASA’s Office of Life Sciences invested a considerable amount of money in the design and development of life-detection instruments. Three of these instruments were chosen to fly aboard the 1976 Viking mission to Mars. The twin Viking landers were designed to land on the Red Planet and search for the presence of life or organic materials on the surface.
Post-Viking Era
The Viking landers touched down on the surface of Mars in July and September 1976. Although the results were eagerly awaited by many on Earth, scientists were disappointed to find that the data from the landers were ambiguous. While one of the instruments did seem to show a positive detection of life,8 the other two life-detection instruments did not.9,10 Moreover, a fourth experiment revealed no sign of organic material in the samples of martian regolith analyzed.11 Scientists later demonstrated that the positive results from the single experiment likely resulted from abiotic processes related to the highly oxidizing nature of the martian surface material.12
In the wake of Viking’s failure to unambiguously detect biological activity or, even, organic compounds in the martian soil, the exobiology program experienced a decrease in political support. The public, which had been so enthusiastic about the possibility of life on other planets, became disillusioned by the negative results of Viking. Not only did the prestige of exobiology suffer, but the entire Mars exploration program also experienced a lull in the two decades following Viking.
Although funding did not reach pre-Viking levels in this era, work in the field continued. The scientific community remained interested in studying the origins of life, and internal NASA advisory committees and independent groups continued scientific planning for future endeavors in this area. Many significant discoveries were also made in this time period. Indeed, NASA’s strategy of actively seeking out interdisciplinary projects that did not readily find a home in other funding agencies was extremely successful and resulted in the funding of many seminal research activities that proved of lasting value. Examples of important research opportunities funded by the Exobiology program include the following: Lynn Margulis’s work on the endosymbiotic origins of eukaryotic cells, Carl Woese’s discovery of the Archaea, Luis Alvarez’s theory of an asteroid as the cause of the Cretaceous-Tertiary mass extinction, the discovery of microfossils of the earliest life on Earth, and James Lovelock’s Gaia hypothesis.13 This does not mean that other agencies made no contributions to the nurturing of what would later be called astrobiology. NSF, for example, was instrumental in funding many important research activities, including the following: Stanley Miller’s work on prebiotic synthesis; the collection of lunar, martian, and other meteorites in Antarctica; and Geoffrey Marcy’s search for exoplanets, i.e., planets around other stars.14
In 1995, astronomers announced the discovery of an extrasolar planet orbiting the star 51 Pegasi. Although this planet orbits very close to its parent star and is far too hot to harbor life as we know it, this unexpected discovery, taken together with the earlier discovery of planets in orbit around a pulsar, generated enthusiasm for the possibility for countless yet-to-be-discovered planetary systems, some of which could have the potential to sustain life. At about the same time, the Hubble Space Telescope obtained spectacular images of disks around young stars, which were interpreted as possible sites for future formation of planets, perhaps including ones with environmental conditions suitable for life.
Much work was also being done at this time on the existence of life in extreme terrestrial environments, such as deep-sea hydrothermal vents. These new “extreme” life forms expanded the limits of what were once considered to be acceptable conditions for life to develop and proliferate. Finally, observations from the Galileo spacecraft suggested that liquid water existed below Europa’s icy surface, raising the tantalizing idea that life could be found elsewhere in the solar system outside the traditional habitable zone.
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Transformation and Revitalization
The August 16, 1996, issue of Science contained an article that once again ignited interest in the possibility of life beyond Earth. The authors of the article claimed that they had discovered evidence suggesting that ancient fossilized bacteria were present in the meteorite ALH 84001, a piece of Mars collected in Antarctica in 1984.15 They based this claim on four pieces of evidence: (1) the presence of carbonate globules which had been formed at temperatures favorable for life, (2) the presence of biominerals (magnetites and sulfides) with characteristics nearly identical to those formed by certain bacteria, (3) the presence of indigenous reduced carbon within martian materials, and (4) the presence in the carbonate globules of features similar in morphology to biological structures.
The extraordinary claim of past life from Mars was eagerly reported by the media but received a very skeptical reaction from many researchers. Very little time passed before criticisms of the article were published, sparking a debate over the true nature of the supposed martian “bacteria.” The authors of these opposing articles argued that the putative nanometer-scale microfossils proposed by the discovery team were highly suspect and likely to be of abiotic origin. The formation temperature of the carbonate globules was soon controversial and, in some cases, suggested a value far above the upper limit for life. Some features were very similar to artifacts produced by the application of conductive coatings onto samples during their preparation for study using scanning electron microscopy. In many cases, the supposed biotic features were regarded as too small to support cellular-based metabolisms. It was known that many features resembling morphological and chemical biomarkers are actually formed by abiotic processes. In addition, most of the organic compounds extracted from ALH 84001 showed radiocarbon activity, indicating that they were very young and had been introduced after the meteorite landed on Earth.
The debate concerning the validity of the claims about ALH 84001 played a pivotal role in the development of astrobiology.16 Although the initial suggestions surrounding ALH 84001 have not been sustained, the announcement triggered a political and programmatic reaction out of all proportion to its scientific significance. In response to congressional calls for a space summit—to discuss “the recent evidence that life may have existed on Mars, as well as other significant advances in space science and technology”17—the White House’s Office of Science and Technology Policy and NASA requested that the NRC’s Space Studies Board organize a workshop to discuss the implications of ALH 84001 and other recent advances in the space sciences. The resulting workshop was held on October 28-30, 1996, and concluded that the study of the origins of life, planetary systems, stars, galaxies, and the universe is a powerful organizing theme for NASA’s space science activities. A subsequent briefing of the workshop results to Vice President Gore concluded that the recent discoveries—such as those concerning life in extreme environments, planets around other stars, a subsurface ocean on Europa, and the transfer of material from planet (e.g., Mars) to planet (e.g., Earth) in the form of meteorites—“… are astonishing returns being reaped from years of investment in many scientific disciplines. Now is the time to leverage that investment and to pursue the quest for origins into the 21st Century.”18 On February 6, 1997, President Clinton proposed that funds be appropriated for a major new NASA activity—the Origins Initiative—to focus on studying the origins of life in the context of the formation of planets, stars, and galaxies. This initiative included funding for missions to Mars and Europa, several astrophysical projects, and the initiation of a major program in astrobiology.
THE NASA ASTROBIOLOGY INSTITUTE
The planning for NASA’s Astrobiology program built on several parallel activities that had taken place earlier in the 1990s. As is mentioned above, NASA’s long-standing Exobiology program had achieved much success by concentrating on the funding of activities that did not readily fit within the more rigid disciplinary boundaries favored by other funding agencies. Thus, the Exobiology program naturally gravitated to inter- and cross-disciplinary activities. The concept of a virtual institute focusing on interdisciplinary research related to the origin, evolution, and distribution of life in the universe was pioneered in 1992 within the context of a program to establish several so-called NASA Specialized Centers of Research and Training (NSCORTs). An NSCORT focusing on issues relating to the origins and evolution of life, the so-called NSCORT in Exobiology—initially consisting of five principal investigators (PIs) and 20 students divided among the Salk Institute for Biological Studies, Scripps Institution of Oceanography, Scripps Research Institute, and University of California, San Diego—was established
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soon thereafter. The NSCORT program proved so popular that, a few years later, a second NSCORT—the New York Center for Studies on the Origins of Life—was established, linking researchers and students at Rensselaer Polytechnic Institute, the State University of New York at Albany, and the College of St. Rose. The NSCORTs in New York and California were eventually funded for periods of 5 and 10 years, respectively.
In parallel with the NSCORT activity, scientists at NASA’s Ames Research Center drew up plans for a “life in the universe” program that would open up many new scientific possibilities by merging many different research activities underway at the center. The proposal was well received by NASA officials, but the name of the proposed endeavor was changed to astrobiology, thus independently reinventing the term that fell out of usage in the late 1950s. The Ames initative, as well as the subsequent efforts to define astrobiology, laid the foundations of modern astrobiology. Ames was named NASA’s Lead Center in Astrobiology by Administrator Dan Goldin in May 1995. Ames personnel soon began holding workshops and meetings to explore models for the best way to perform astrobiology and related multidisciplinary research.
Meanwhile, Gerald Soffen, then the head of University Programs at NASA’s Goddard Space Flight Center and formerly the principal scientist on the Viking missions to Mars, independently developed a concept for an institute focusing on astrobiology. Soffen’s vision was for an institute having the following characteristics:
Play a key role in determining the future of astrobiology;
Be both real and virtual, using modern communications technology;
Provide access to a continuous council of technical experts;
Employ an interdisciplinary approach; and
Recommend research directions, priorities, experiments, missions, and technology developments to NASA management.
The culmination of efforts of both Soffen and researchers at Ames came in May 1998 when 11 geographically dispersed teams of scientists (see Table 1.1) were named as the initial members of the NASA Astrobiology Institute (NAI). The teams, selected on a competitive basis in response to a cooperative-agreement notice (CAN) issued in 1997, were awarded funding of approximately $1 million a year for 5 years. The NAI formally opened for business in July 1998 under the leadership of Interim Director Scott Hubbard. Nobel laureate Baruch S. Blumberg was named the first NAI director in 1999.
From its founding, the NAI has actively nurtured partnerships with international organizations interested in astrobiology. Such partnerships are entered into on the basis of no exchange of funds and have the overall goal of providing collaborative opportunities for NAI researchers via, for example, access to unique scientific facilities and field sites outside the United States. Foreign astrobiology organizations can propose to become either an associate or an affiliate member of the NAI. The former arrangement involves a formal agreement between NASA and a foreign government, and the associated entity has the same status as one of the NAI’s domestic nodes, whereas the latter is a much looser arrangement that does not involve a formal government-to-government agreement. The NAI’s affiliate and associate members are selected via an application process that considers their organizational nature, the types of scientific activities in which they are engaged and their relationship to NAI objectives, and the likely productivity of the proposed activities. The Centro de Astrobiología in Spain became the first associate member of the NAI in 1999.
A second CAN was issued in 2000 and resulted in the selection of four new NAI teams, bringing the total number of NAI institutions to 15 (see Table 1.1). The Australian Centre for Astrobiology was also established, and it became the second associate member of the NAI.
In 2000, in response to a request from NASA’s Office of Space Science, the National Research Council’s Committee on the Origins and Evolution of Life (COEL), a joint committee of the Space Studies Board and the Board on Life Sciences, was charged to assess the state of the NASA Astrobiology program. COEL’s report, entitled Life in the Universe: An Assessment of U.S. and International Programs in Astrobiology, was published in 2002.
In 2003, the 5-year funding period for the 11 original NAI members teams ended. Six of these teams successfully applied for and were awarded funding for an additional period of 5 years. In addition, six new teams were funded (see Table 1.1). Bruce Runnegar, a professor in UCLA’s Department of Earth and Space Sciences and
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the Institute of Geophysics and Planetary Physics, also became the new director of the NAI. In addition, NASA released a revised version of the original 1998 Astrobiology Roadmap outlining the fundamental goals and objectives of astrobiology (Table 1.2).19
The year 2004 marked the establishment of the Federation of Astrobiology Organizations (FAO), whose goal is “to create an architecture that can implement cooperative international activities central to the interests of the individual astrobiology networks, associations, institutes, and societies that comprise [the] federation.” The federation consists of the NAI as well as groups from Britain, Australia, Mexico, Spain, France, Germany, and Sweden.
Carl Pilcher, the former director of NASA’s solar system exploration program, took over as NAI director in 2006. The four teams that received funding in 2001 also completed their 5-year agreements, and membership in the NAI dropped to 12 teams. Because of budgetary restrictions, these four teams were not replaced until 2007.
The NAI currently consists of 16 teams (see Table 1.1) and involves the work of approximately 600 investigators distributed across some 150 institutions. The NAI is administered by its director20 and a small staff, through an office known as NAI Central,21 located at the NASA Ames Research Center.
The NAI’s teams (“nodes”) are supported through cooperative agreements between NASA and the teams’ institutions;22 these agreements involve substantial contributions from NASA and each of the teams. The NAI Handbook outlines the expectations of membership in the institute, emphasizing active participation in realizing all aspects of the NAI’s mission.23
The principal investigators of each team, together with the NAI director and deputy director, constitute the executive council.24 Its role is to advise NAI management in matters of institute-wide research, space mission activities, technological development, and external partnerships.
Other aspects of the NAI include the Director’s Seminar Series, which brings the community together monthly via videoconference to share scientific progress;25 focus groups that mobilize expertise within the community on relevant topics;26 the annual report, which describes the most recent activities of each of the NAI’s teams;27 the online Research Archive, which highlights top scientific discoveries and advances;28 and the NAI Newsletter, which provides the latest news about activities and opportunities.29 Special attention to the next generation of astrobiologists is exemplified by the NAI’s Postdoctoral Fellowship Program30 and the Lewis and Clark Fund for Exploration and Field Research.31 NAI Central also organizes institute-wide workshops, such as the Strategic Impact Workshop,32 to facilitate collective discussion and planning for the NAI’s research.
The NAI continues to adapt and evolve in a changing environment. Most recently, the NAI’s 2007 Director’s Discretionary Fund competition emphasized a strategic impact on NASA’s ability to achieve its goals,33 especially in the areas of flight missions, cross-program synergies, collaborations with other funding agencies, and external partnerships.
CURRENT STATUS OF NASA’S ASTROBIOLOGY PROGRAM
NASA’s Astrobiology program currently resides within the Planetary Science Division of NASA’s Science Mission Directorate and consists of four different programmatic elements:
The NASA Astrobiology Institute (NAI), a consortium of 16 competitively selected, principal investigator-led teams conducting interdisciplinary research at geographically dispersed research institutions. The NAI’s budget for fiscal year 2008 is about $16 million.
The Exobiology and Evolutionary Biology grants programs, which currently fund some 150 individual principal investigators located at U.S. universities, research institutions, federal laboratories, and NASA centers. The combined budget of these two programs in fiscal year 2008 is about $11 million.
The Astrobiology Science and Technology Instrument Development (ASTID) program, which funds the initial development of new, astrobiology-relevant instruments that may be selected for future flight opportunities. The program currently funds some 49 instrument-development projects at U.S. universities, research institutions, federal laboratories, and NASA centers. The ASTID program budget for fiscal year 2008 is about $9 million.
The Astrobiology Science and Technology for Exploring Planets (ASTEP) programs, which fund the field-testing of new, astrobiology-relevant instruments in terrestrial settings representative in some way of the extrater-
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TABLE 1.1 Members of the NASA Astrobiology Institute, 1998 to Present
Node
Node Name/Theme of Research
Principal Investigator
Selected in Competition for CAN Number
Period of NAI Funding
Arizona State University
Exploring the Living Universe: Origin, Evolution, and Distribution of Life in the Solar System
John Cronin
Jack Farmer
1
1998-2003
NASA Ames Research Center
Linking Our Origins to Our Destiny
David Des Marais
1, 3
1998-2008
Carnegie Institution of Washington
Astrobiological Pathways: From the Interstellar Medium, Through Planetary Systems, to the Emergence and Detection of Life
Sean Solomon
1, 3
1998-2008
Harvard University
The Planetary Context of Biological Evolution
Andrew Knoll
1
1998-2003
Jet Propulsion Laboratory
Definition and Detection of Biosignatures
Kenneth Nealson
1
1998-2003
NASA Johnson Space Center
Center for the Study of Biomarkers in Astromaterials
David McKay
1
1998-2003
Marine Biological Laboratory
Marine Biological Laboratory Astrobiology Science Team/Environmental Genomes and Evolution of Complex Systems in Simple Organisms
Mitchell Sogin
1, 3
1998-2008
Pennsylvania State University
Penn State Astrobiology Research Center/Evolution of a Habitable Planet
Hiroshi Ohmoto
1, 3
1998-2008
Scripps Research Institute
Self-Producing Molecular Systems and Darwinian Chemistry
Reza Ghadiri
1
1998-2003
University of California, Los Angeles
From Stars to Genes: An Integrative Study of the Prospects for Life in the Cosmos
Bruce Runnegar
Edward Young
1, 3
1998-2008
University of Colorado
University of Colorado Center for Astrobiology
Bruce Jakosky
1, 3
1998-2008
Michigan State University
Center for Genomic and Evolutionary Studies on Microbial Life at Low Temperatures
Michael Tomashow
2
2001-2006
restrial environments in which they may be eventually deployed. The program currently funds six field campaigns and/or two advanced-instrument projects based at U.S. research institutions, universities, and NASA centers. The ASTEP program budget for fiscal year 2008 is about $5 million.
In response to language in the NASA Authorization Act of 2000 and a subsequent request from NASA, the Astrobiology program and related U.S. and international programs relating to the detection of life in the universe were formally reviewed by the National Research Council. The resulting report, Life in the Universe: An Assessment of U.S. and International Programs in Astrobiology, commented that “remarkable progress has been made over a short period of time in defining the key scientific questions, initiating research and training programs, and developing collaborations on a national and international scale.”34 The report identified five issues that NASA needed to address in the near term to ensure the health of the Astrobiology program:35
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Node
Node Name/Theme of Research
Principal Investigator
Selected in Competition for CAN Number
Period of NAI Funding
University of Rhode Island
Subsurface Biospheres
Steven D’Hondt
2
2001-2006
University of Washington
Planetary Habitability and Evolution of Biological Complexity
Peter Ward
2
2001-2006
California Institute of Technology
Virtual Planetary Laboratory/Exploring the Habitability and Biosignatures of Extrasolar Terrestrial Planets
Victoria Meadows
2, 4
2001-2006 and 2007-2012
University of California, Berkeley
BioMars/Biospheres of Mars: Ancient and Recent Studies
Jillian Banfield
3
2003-2008
NASA Goddard Space Flight Center
Origin and Evolution of Organics in Planetary Systems
Michael Mumma
3
2003-2008
Indiana University
Indiana-Princeton-Tennessee Astrobiology Institute
Lisa Pratt
3
2003-2008
SETI Institute
SETI Institute NAI Team/Planetary Biology, Evolution and Intelligence
Christopher Chyba
Rocco Mancinelli
3
2003-2008
University of Arizona
Life and Planets Astrobiology Center/Astronomical Search for the Essential Ingredients of Life: Placing Our Habitable System in Context
Neville Woolf
3
2003-2008
University of Hawaii, Manoa
Origin, History and Distribution of Water and Its Relation to Life in the Universe
Karen Meech
3
2003-2008
Massachusetts Institute of Technology
Requirements for Development and Maintenance of Multicellular Life
Roger Summons
4
2007-2012
Montana State University
Astrobiology Biocatalysis Research Center
John Peters
4
2007-2012
University of Wisconsin, Madison
Organic and Mineralogical Signatures and Environments of Life on Earth and Other Planetary Bodies
Clark Johnson
4
2007-2012
Definition of astrobiology and its goals. In particular, the perception in some circles at the time the study was undertaken that astrobiology as both an intellectual endeavor and a NASA program is ill-defined.
Evaluation of the impact of the NAI on astrobiology. Has the NAI affected astrobiology in a way that a standard, principal-investigator grants program could not have? The report recommended as essential that a review of the impact of the NAI on astrobiology be conducted.
Review/retirement of existing programs. Should existing NAI nodes be forced to recompete for funds every 5 years or should some other mechanism be devised to ensure the continuation of productive research teams?
Insularity of the NAI. The report expressed concern about the potential tendency to regard astrobiology as a private club whose membership is exclusively confined to those researchers affiliated with the NAI.
The “astro” in astrobiology. Despite considerable overlap in areas of scientific interest, the astronomical community had little involvement in astrobiology at the time the report was drafted.
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TABLE 1.2 Astrobiology Roadmap—Fundamental Goals and Objectives of Astrobiology
Goals
Objectives
1.0 Understand the nature and distribution of habitable environments in the universe by determining the potential for habitable planets beyond the solar system, and characterize those that are observable.
1.1 Investigate how solid planets form, acquire liquid water and other volatile species and organic compounds, and how processes in planetary systems and galaxies affect their environments and habitability. Use theoretical and observational studies of the formation and evolution of planetary systems and their habitable zones to predict where water-dependent life is likely to be found in such systems.
1.2 Conduct astronomical, theoretical, and laboratory spectroscopic investigations to support planning for and interpretation of data from missions to detect and characterize extrasolar planets.
2.0 Explore for past or present habitable environments, prebiotic chemistry and signs of life elsewhere in the solar system by determining any chemical precursors of life and any ancient habitable climates in the solar system, and characterize any extinct life, potential habitats, and any extant life on Mars and in the outer solar system.
2.1 Through orbital and surface missions, explore Mars for potentially habitable environments, as evidenced by water or aqueous minerals. Study martian meteorites to guide future Mars exploration. Develop the methods and supporting technologies for the in situ characterization of aqueous minerals, carbon chemistry and/or life.
2.2 Conduct basic research, develop instrumentation to support astrobiological exploration and provide scientific guidance for outer solar system missions. Such missions should explore the Galilean moons Europa, Ganymede and Callisto for habitable environments where liquid water could have supported prebiotic chemical evolution or life. Explore Saturn’s moon, Titan, for environments favorable for complex prebiotic synthesis or life.
3.0 Understand how life emerges from cosmic and planetary precursors by performing observational, experimental and theoretical investigations to understand the general physical and chemical principles underlying the origins of life.
3.1 Characterize the cosmic and endogenous sources of matter (organic and inorganic) for potentially habitable environments in the solar system and in other planetary and protoplanetary systems.
3.2 Identify multiple plausible pathways for the condensation of prebiotic monomers into polymers. Identify the potential for creating catalytic and genetic functions, and mechanisms for their assembly into more complex molecular systems having specific properties of the living state. Examine the evolution of artificial chemical systems that model processes of natural selection to understand better the molecular processes associated with prebiological evolution in the universe.
3.3 Identify prebiotic mechanisms by which available energy can be captured by molecular systems and used to drive primitive metabolism and polymerization reactions.
3.4 Investigate both the origins of membranous boundaries on the early Earth and the associated properties of energy transduction, transport of nutrients, growth, and division. Investigate the origins and early coordination of key cellular processes such as metabolism, energy transduction, translation and transcription. Without regard to how life actually emerged on Earth, create and study artificial chemical systems that undergo mutation and natural selection in the laboratory.
4.0 Understand how past life on Earth interacted with its changing planetary and solar system environment by investigating the historical relationship between Earth and its biota by integrating evidence from both the geologic and biomolecular records of ancient life and its environments.
4.1 Investigate the development of key biological processes and their environmental consequences during the early history of Earth through molecular, stratigraphic, geochemical, and paleontological studies.
4.2 Study the origins and evolution of life forms that eventually led to more complex multi-cellular biota that appear in the fossil record or exist today.
4.3 Examine the records of the response of Earth’s biosphere (both the habitable environment and biota) to extraterrestrial events, including asteroid and comet impacts.
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Goals
Objectives
5.0 Understand the evolutionary mechanisms and environmental limits of life by determining the molecular, genetic, and biochemical mechanisms that control and limit evolution, metabolic diversity, and acclimatization of life.
5.1 Experimentally investigate and observe the evolution of genes, metabolic pathways, genomes, and microbial species. Experimentally investigate the forces and mechanisms that shape the structure, organization, and plasticity of microbial genomes. Examine how these forces control the genotype-to-phenotype relationship. Conduct environmental perturbation experiments on single microbial species to observe and quantify adaptive evolution to astrobiologically relevant environments.
5.2 Experimentally examine the metabolic and genetic interactions in microbial communities that have determined major geochemical processes and changes on Earth. Investigate how these interactions shape the evolution and maintenance of metabolic diversity in microbial communities. Investigate how novel microbial species establish and adapt into existing communities.
5.3 Document life that survives or thrives under the most extreme conditions on Earth. Characterize and elucidate the biochemical capabilities that define the limits for cellular life. Explore the biochemical and evolutionary strategies that push the physical-chemical limits of life by reinforcing, replacing, or repairing critical biomolecules (e.g., spore formation, resting stages, protein replacement rates, or DNA repair). Characterize the structure and metabolic diversity of microbial communities in such extreme environments.
6.0 Understand the principles that will shape the future of life, both on Earth and beyond by elucidating the drivers and effects of ecosystem change as a basis for projecting likely future changes on time scales ranging from decades to millions of years, and explore the potential for microbial life to adapt and evolve in environments beyond its planet of origin.
6.1 [Characterize] [e]nvironmental changes and the cycling of elements by the biota, communities, and ecosystems.
6.2 Explore the adaptation, survival and evolution of microbial life under environmental conditions that simulate conditions in space or on other potentially habitable planets. Insights into survival strategies will provide a basis for evaluating the potential for interplanetary transfer of viable microbes and also the requirements for effective planetary protection.
7.0 Determine how to recognize signatures of life on other worlds and on early Earth by identifying biosignatures that can reveal and characterize past or present life in ancient samples from Earth, extraterrestrial samples measured in situ, samples returned to Earth, remotely measured planetary atmospheres and surfaces, and other cosmic phenomena.
7.1 Learn how to recognize and interpret biosignatures which, if identified in samples from ancient rocks on Earth or from other planets, can help to detect and/or characterize ancient and/or present-day life.
7.2 Learn how to measure biosignatures that can reveal the existence of past or present life through remote observations.
SOURCE: Excerpted from revised NASA Astrobiology Roadmap; see http://nai.arc.nasa.gov/roadmap/.
Despite the concerns about these five issues, the report concluded that NASA’s Astrobiology program “is well poised to catalyze fundamentally important discoveries concerning the origins of life, its distribution in the cosmos, and the long-term fate of life on Earth.”36 Now, 5 years after Life in the Universe was drafted, the first and fifth items above are no longer regarded as issues of general concern. The remaining three items, all focusing on the NAI, are directly or indirectly the subject of this report.
A discussion of the role of astrobiology in the context of a traditional space-science discipline can be found in Astronomy and Astrophysics in the New Millennium,37 the most recent astronomy and astrophysics decadal survey report, which comments that “… researchers can recognize the signature of life elsewhere only by understanding better the history of life on Earth over the past 4 billion years and exploring more deeply the possibility that life has
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also had an independent history on Mars or other planets and moons in our solar system. This study is an essential part of the new synergy between astronomy, planetary science, and biology—what has been called astrobiology” (p. 157). The decadal survey continues by noting (pp. 157-158) that astrobiology has the potential to:
“… encourage collaborations across … disciplines in order to address questions that compel the imaginations of scientists and citizens alike.”
“… draw together investigators from disciplines that in the past have shared little except a common interest in understanding the natural world.”
“… [bring] diverse scientific cultures together at the right moment in time.”
“… [generate] extraordinary public interest … by [its] attempts to understand our origins and the ubiquity of life in the universe.”
“… link the seemingly abstract world of research at the frontiers of knowledge to questions that have excited the human imagination since people first gazed at the heavens.”
Another discussion of the role of astrobiology in the context of a traditional space-science activity can be found in New Frontiers in the Solar System: An Integrated Exploration Strategy,38 the first solar system exploration (SSE) decadal survey. That document highlights the role of astrobiology in (p. 158):
“… [providing] a scientific organizational structure that integrates a wide subset of solar system issues and questions that span the origins, evolution, and extinction of life.”
“… [allowing] nonexperts to grasp the connections between different component disciplines within planetary science and to do so in a way that most people will appreciate as addressing core themes in human thought.”
“… [being] the primary means by which NASA tries to implement one of its prime objectives—understanding life’s origins and its distribution in the universe.”
“… [becoming] a fundamental part of the solar system exploration strategy.”
In summary, the SSE decadal survey report “… encourages NASA to continue the integration of astrobiology science objectives with those of other space science disciplines. Astrobiological expertise should be called upon when identifying optimal mission strategies and design requirements for flight-qualified instruments that [will] address key questions in astrobiology and planetary science” (p. 9).
The goals of astrobiology have not only figured prominently in NRC reports. In outlining plans to implement the Vision for Space Exploration—the initiative to return humans to the Moon and, ultimately, to Mars—President George W. Bush charged NASA to conduct robotic exploration of Mars to search for evidence of life; to explore Jupiter’s moons, asteroids, and other bodies to search for evidence of life; and to undertake advanced telescopic searches for Earth-like planets and habitable environments around other stars.39 These fundamental, astrobiology goals, enunciated by President Bush in 2004 as the science component of the Vision, figure prominently in NASA strategy planning documents.40
The most recent NRC comments on the role, scope, and status of NASA’s Astrobiology program are made in An Assessment of Balance in NASA’s Science Programs.41 This document makes the following points (p. 20):
“The decadal surveys for astrophysics and for solar system exploration both embraced astrobiology as a key component of their programs, with the questions encompassed by astrobiology serving as overarching themes for the programs as a whole.”
“The missions put forward in the solar system exploration survey are all key missions in astrobiology, whether they are labeled as such or not. And issues and missions related to astrobiology represent one of the key areas of interest identified in the astronomy and astrophysics communities.”
“Astrobiology provides the intellectual connections between otherwise disparate enterprises.”
The report continues by recognizing that: “NASA’s Astrobiology program creates an integrated whole and supports the basic interdisciplinary nature of the field. Further, the Vision [for Space Exploration] is, at its heart,
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Assessment of the NASA Astrobiology Institute
FIGURE 1.1 The budgetary history of the four elements constituting NASA’s Astrobiology program. The program is currently operating on an annual budget of approximately $4 million more that the figure indicated for fiscal year 2007. Courtesy of John D. Rummel, NASA Science Mission Directorate.
largely an astrobiology vision with regard to the science emphasis [footnote omitted]. In developing the future of the program, the missions actually feed forward from the basic science. Astrobiology is just beginning the type of synthesis and integration that will allow it to provide science input for future mission development. Without it, the science and the scientific personnel will not be in place to support the missions when they do fly.”42
Despite favorable reviews by the NRC and almost a decade’s worth of steady budget increases (Figure 1.1), the astrobiology community was shocked to learn that NASA’s proposed budget for Fiscal Year 2007 included a 50 percent cut for the Astrobiology program. The reason why the program was singled-out for a cut of 50 percent when other programs were only cut by 15 percent has never been explained satisfactorily.
Some slight budgetary relief came in 2007 when approximately $4 million was added back to the program from SMD discretionary funds and a reallocation of resources within SMD’s Planetary Science Division. Nevertheless, the current expectation is that NASA’s Astrobiology budget will remain at approximately the FY2007-level with annual corrections for inflation. Thus, the Astrobiology program enters its second decade with a major disconnect between the resources allocated to its execution and the important role ascribed to the program in NASA and NRC strategic plans.
NOTES
1. See, for example, S.J. Dick and J.E. Strick, The Living Universe: NASA and the Development of Astrobiology, Rutgers University Press, New Brunswick, New Jersey, 2004, pp. 205-213.
2. L.J. Mix et al. (eds.), “The Astrobiology Primer: An Outline of General Knowledge—Version 1, 2006,”. Astrobiology 6: 735-813, 2006. Available at http://www.liebertonline.com/doi/pdfplus/10.1089/ast.2006.6.735.
3. See, for example, http://www.nai.arc.nasa.gov/about/about_nai.cfm#overview.
4. L.J. Lafleur, “Astrobiology,” Astronomical Society of the Pacific Leaflets 3: 333-340, 1941.
5. See, for example, H. Sturghold, The Green and Red Planet, University of New Mexico Press, Albuquerque, New Mexico, 1953; O. Struve, “Life on Other Worlds,” Sky and Telescope 14: 137-146, 1955; or A.G. Wilson, “Problems Common to the Fields of Astronomy and Biology: A Symposium—Introduction,” Publications of the Astronomical Society of the Pacific 70: 41-43, 1958.
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6. See, for example, S.J. Dick and J.E. Strick, The Living Universe: NASA and the Development of Astrobiology, Rutgers University Press, New Brunswick, New Jersey, 2004, pp. 204-205.
7. J.E. Strick, “Creating a Cosmic Discipline: The Crystallization and Consolidation of Exobiology, 1957-1973,” Journal of the History of Biology 37: 131-180, 2004.
8. V.V. Levin and P.A. Straat, “Recent Results from the Viking Labeled Release Experiment on Mars,” Journal of Geophysical Research 82: 4663-4667, 1977.
9. N.H. Horowitz, G.L. Hobby, and J.S. Hubbard, “Viking on Mars: The Carbon Assimilation Experiments,” Journal of Geophysical Research 82: 4659-4662, 1977.
10. V.I. Oyama and B.J. Berdahl, “The Viking Gas Exchange Experiment Results from Chryse and Utopia Surface Samples,” Journal of Geophysical Research 82: 4669-4676, 1977.
11. K. Biemann, J. Oro, P. Toulmin III, L.E. Orgel, A.O. Nier, D.M. Anderson, D. Flory, A.V. Diaz, D.R. Rushneck, and P.G. Simmonds, “The Search for Organic Substances and Inorganic Volatile Compounds in the Surface of Mars,” Journal of Geophysical Research 82: 4641-4662, 1977.
12. N.H. Horowitz, To Utopia and Back: The Search for Life in the Solar System, Freeman, New York, New York, 1986, pp. 134-136 and 137-138.
13. See, for example, S.J. Dick and J.E. Strick, The Living Universe: NASA and the Development of Astrobiology, Rutgers University Press, New Brunswick, New Jersey, 2004.
14. See, for example, S.J. Dick and J.E. Strick, The Living Universe: NASA and the Development of Astrobiology, Rutgers University Press, New Brunswick, New Jersey, 2004, pp. 204-205.
15. D.S. McKay, E.K. Gibson, Jr., K.L. Thomas-Keprt, H. Vali, C.S. Romanek, S.J. Clemett, X.D.F. Chillier, C.R. Maechling, and R.N. Zare, “Search for Past Life on Mars: Possible Relic Biogenic Activity in Martian Meteorite ALH 84001,” Science 273: 924-930, 1996.
16. See, for example, D.H. Smith, “Astrobiology in the United States: A Policy Perspective,” in Astrobiology: Future Perspectives, P. Ehrenfreund et al. (eds.), Kluwer, Dordrecht, The Netherlands, 2004.
17. Letter from J.H. Gibbons, Assistant to the President for Science and Technology, to D.S. Goldin, Administrator, NASA, September 25, 1996.
18. C.R. Canizares, A.I. Sargent, et al., The Search for Origins: Findings of a Space Science Workshop, National Aeronautics and Space Administration, Washington, D.C., 1996.
19. For more information concerning the Astrobiology Roadmap see http://nai.arc.nasa.gov/roadmap/.
20. For more information about the NAI Director see http://nai.arc.nasa.gov/about/about_nai.cfm#director.
21. For more information about NAI Central see http://nai.nasa.gov/team/index_nai.cfm.
22. For more information about cooperative agreements see http://nai.nasa.gov/tools/handbook/3.cfm#CAN.
23. For more information about the NAI Handbook see http://nai.nasa.gov/tools/handbook/.
24. For more information about the Executive Council see http://nai.nasa.gov/ec/index.cfm.
25. For more information about the Director’s Seminar Series see http://nai.nasa.gov/seminars/index.cfm#1.
26. For more information about the focus groups see http://nai.nasa.gov/about/focus_groups.cfm.
27. For more information about the annual report see http://nai.arc.nasa.gov/team/execsumms.cfm.
28. For more information about the Research Archive see http://nai.nasa.gov/news_stories/news_archive.cfm?member.
29. For more information about the NAI Newsletter see http://nai.nasa.gov/newsletter/index.cfm.
30. For more information about the Astrobiology Roadmap see http://nai.nasa.gov/funding/PostDocList.cfm.
31. For more information about the Lewis and Clark Fund see http://nai.nasa.gov/funding/index.cfm#lc.
32. For more information about the Strategic Impact Workshop see http://nai.nasa.gov/ec/siw.cfm.
33. For more information about the Director’s Discretionary Fund see http://nai.arc.nasa.gov/ddf_2007/index.cfm.
34. National Research Council, Life in the Universe: An Assessment of U.S. and International Programs in Astrobiology, The National Academies Press, Washington, D.C., 2003, p. 7.
35. National Research Council, Life in the Universe: An Assessment of U.S. and International Programs in Astrobiology, The National Academies Press, Washington, D.C., 2003, p. 1.
36. National Research Council, Life in the Universe: An Assessment of U.S. and International Programs in Astrobiology, The National Academies Press, Washington, D.C., 2003, p. 1.
37. National Research Council, Astronomy and Astrophysics in the New Millennium, National Academy Press, Washington, D.C., 2001.
38. National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Washington, D.C., 2003.
39. G.W. Bush, “A Renewed Spirit of Discovery: The President’s Vision for U.S. Space Exploration,” in The Vision for Space Exploration, NP-2004-01-334-HQ, NASA, Washington, D.C., 2004.
40. See, for example, National Aeronautics and Space Administration, Science Plan For NASA’s Science Mission Directorate 2006-2016, NP-2007-03-461-HQ, NASA, Washington, D.C., 2007, pp. 31-32.
41. National Research Council, An Assessment of Balance in NASA’s Science Programs, The National Academies Press, Washington, D.C., 2006.
42. National Research Council, An Assessment of Balance in NASA’s Science Programs, The National Academies Press, Washington, D.C., 2003, p. 20.
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