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  • 太空生物学

    太空生物学(Astrobiology,Exobiology)顾名思义就是是研究生物和外空间物体的相互作用的科学,是一门广泛涉及生物学、化学、物理学、地质学和天文学等多门学科的交叉科学。是研究关于地球以及整个宇宙的生命的起源、进化、分布和未来的科学。

    编辑摘要

    目录

    概述/太空生物学 编辑

    太空生物学(Astrobiology,Exobiology)是研究生物和外空间物体的相互作用的科学。是研究关于地球以及整个宇宙的生命的起源、进化、分布和未来的科学。其中要回答的最基本的问题就是:生命是怎样起源的?空间生命的未来会怎样?我们是宇宙中的唯一生命体吗?太空生物学是一个新兴而迅速发展的领域,吸引了大量的政府基金和优秀的科学家。2003年10月15日我国“神舟”五号载人飞船成功发射以及随后的安全着陆,标志着中国在攀登世界科技高峰中,迈出了有重大历史意义的一步。中华民族在航天事业上的发展必将翻开新的篇章。

    英文介绍/太空生物学 编辑

    Astrobiology, the transcendent science: the promise of

    astrobiology as an integrative approach for science

    and engineering education and research

    James T Staley

    Astrobiology is rapidly gaining the worldwide attention of

    scientists, engineers and the public. Astrobiology’s captivation is

    due to its inherently interesting focus on life, its origins and

    distribution in the Universe. Because of its remarkable breadth as

    a scientific field, astrobiology touches on virtually all disciplines in

    the physical, biological and social sciences as well as

    engineering. The multidisciplinary nature and the appeal of its

    subject matter make astrobiology ideal for integrating the

    teaching of science at all levels in educational curricula. The

    rationale for implementing novel educational programs in

    astrobiology is presented along with specific research and

    educational policy recommendations.

    Addresses

    Department of Microbiology, NSF Astrobiology IGERT Program,

    University of Washington, Box 357242, Seattle, WA 98195, USA

    Current Opinion in Biotechnology 2003, 14:347–354

    This review comes from a themed issue on

    Science policy

    Edited by Rita R Colwell

    0958-1669/03/$ – see front matter

    2003 Elsevier Science Ltd. All rights reserved.

    DOI 10.1016/S0958-1669(03)00073-9

    Abbreviations

    NAI NASA Astrobiology Institute

    NASA National Aeronautics and Space Administration

    NSF National Science Foundation

    SETI search for extraterrestrial intelligence

    Introduction

    This article introduces the multidisciplinary field of astrobiology,

    which bridges the gap between the biological and

    physical sciences and engineering. In addition, recommendations

    are made for astrobiology to serve as an

    alternative model for teaching science and engineering

    at all levels of education including primary, secondary,

    undergraduate and graduate students. I am writing this

    article largely based upon the experience that my colleagues

    and I have had in developing a PhD program in

    astrobiology at the University of Washington.

    What a difference a word makes

    For four decades the National Aeronautics and Space

    Administration (NASA) sponsored a science program on

    exobiology, a term which, by definition, refers to the

    study of life outside Earth. Excluding Earth and earthlings

    seems inappropriate for at least three reasons. First, it

    is ironic to disregard Earth, because it is the only place so

    far known in the Universe where life actually exists.

    Second, exobiology implies that there is something very

    different and strange about creatures from other planetary

    bodies. Why shouldn’t all living matter in the Universe

    share common properties in the same sense as other

    matter? Third, the study of life on Earth, including its

    evolution and diversity, provides valuable clues and lessons

    for the exploration of other worlds that may harbor

    life. After all, if we cannot understand life, its origins and

    its limits on Earth, how can we possibly begin to identify

    life and efficiently study it elsewhere?

    The perception of scientists and lay people has changed

    since NASA introduced the term astrobiology, because

    it optimistically embraces the study of all life in the

    Universe, including life on Earth. The introduction of

    the term astrobiology coincided with NASA’s establishment

    in 1998 of the NASA Astrobiology Institute (NAI),

    which now encompasses about a dozen universities and

    research centers at NASA and elsewhere (http://www.nai.

    arc.nasa、gov). In the five years since the NAI began as

    a virtual institute, an international effort has linked its

    astrobiology program to those of several other countries.

    These include Spain (Centro de Astrobiologia), the United

    Kingdom (UK Astrobiology Forum and Network), France

    (Groupement de Recherche en Exobiologie), Europe

    (The European Exo/Astrobiology Network Association)

    and Australia (Australian Centre for Astrobiology).

    Why is astrobiology so appealing?

    How is it that astrobiology has captured the curiosity,

    fascination and admiration of so many? Surely much of its

    appeal has to do with the great metaphysical questions of

    astrobiology. Where did we come from? How does life

    begin and evolve? What is life’s future? Does life occur

    elsewhere in the universe?

    This young and vigorous field holds great expectations

    that these questions can and will be answered. Herein lies

    the appeal of astrobiology. Not only is the subject matter

    of broad interest to virtually all of us, it is basic to our

    perception of the world in which we live. Furthermore,

    scientists are sanguine about our ability to answer at least

    some of these questions in the foreseeable future. So, it is

    not surprising that the air bristles with excitement and

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    anticipation at astrobiology meetings as scientists report

    how they are unraveling the mysteries of life, its tenacity,

    fragility, distribution and origins.

    The transcendent nature of astrobiology

    Astrobiology is remarkable in its extreme breadth and

    therefore its potential for multidisciplinary education

    and research. It touches on virtually all fields of science

    and engineering. As a result it is perhaps unique among all

    disciplines. Astrobiology is unlike, for instance, biology

    which is exclusively centred on the study of all aspects of

    life on Earth. Astrobiology, by contrast, considers questions

    that transcend our planetary boundary. When biologists

    ask the question ‘What is life?’ they are constrained

    by the range of life forms on Earth. However, when the

    astrobiologist asks the same question, all boundaries are

    removed. The astrobiologist is no longer confined to life

    on Earth, but is forced to conjure possibilities beyond the

    requirements of water and the DNA! RNA! protein

    dogma. Indeed, imagination is the only limitation to the

    astrobiologist’s thinking, although it is a severe one. To

    test your own imagination, contemplate the question

    ‘What is life?’ and propose one or two truly alternative

    life styles to that which we know so well.

    A special multidisciplinary challenge for astrobiology

    relates to the dating of early events on Earth and provides

    another example of its transcendent nature. Geologists

    working with paleontologists provided us with the

    Geological Timetable during the last half of the 20th

    century. From this effort, much was learned about the

    past 600 million years of animal and plant evolution.

    However, little is known about early evolution, that is,

    from the Precambrian Eon after Earth’s formation about

    4.5 billion years ago until 600 million years ago. Our only

    hope to uncover this information is through the mutual

    efforts of geologists, micropaleontologists, microbiologists

    and phylogeneticists. Fossils alone cannot answer

    the important questions about the order in which processes

    such as methanogenesis and sulfate reduction

    occurred, because microbial fossils are too simple. Chemical

    biomarkers for processes and specific microbial

    groups are needed in conjunction with phylogenetic

    analyses. Already astrobiologists from the various disciplines

    are talking with one another about resolving this

    issue through multidisciplinary efforts.

    So, not only does astrobiology provide genuine appeal to

    all, but it is perhaps unique in its transcendence of

    science. It encompasses aspects of biology, astronomy,

    physics, planetary sciences, chemistry and geology as well

    as the social sciences. Example topic areas in astrobiology

    are given in Box 1.

    Interdisciplinary astrobiology research

    Much of the exciting research in astrobiology lies at the

    interface between two or more disciplines. For example,

    microorganisms are intimately involved in rock weathering

    processes. From an astrobiological perspective,

    biological weathering processes leave ‘signatures of life’

    such as specific biological compounds or microbial fossils

    that could be used to identify life on rocks from other

    planetary bodies such asMars. The traditional training of

    geologists and microbiologists does not prepare PhD

    graduates to study these geobiological activities by themselves;

    however, in astrobiology, scientists work together

    in designing and testing hypotheses and thereby expanding

    our understanding of fundamental but poorly studied

    processes.

    In our astrobiology PhD program at the University of

    Washington, we have seen examples of interdisciplinary

    work that have resulted in unique perspectives. It is

    noteworthy in this regard that it is not always the faculty

    who have made these breakthroughs, but it is often our

    PhD students. One example of this is work carried out by

    an astronomy student, John Armstrong, and a biology

    student, Llyd Wells, who have worked with an astronomy

    faculty member, Guillermo Gonzalez. They proposed

    that the Moon, as ‘Earth’s attic’, probably contains

    rocks with microbial fossils and other signatures of life

    from Earth that were ejected to the Moon as it drifted

    away from Earth after its formation. These fossils would

    be well preserved, because they have not been exposed

    to weathering and tectonic processes on Earth. These

    rocks are therefore likely to contain geochemical and

    fossil evidence that may tell us much about early Earth

    history [1]. In a second paper, they suggest that, had a

    major sterilizing impact occurred on Earth following the

    evolution of life, rocks subsequently ejected from the

    Moon by an impact event could have been brought back

    to Earth to re-seed it [2]. These papers are having a

    major influence on NASA’s thinking concerning the

    possibility of launching amission to theMoon to retrieve

    early Earth rocks.

    Another example of interdisciplinary collaboration involves

    two of our faculty members. Peter Ward and Don

    Brownlee, a paleontologist and an astronomer, respectively,

    have collaborated in writing two recent provocative

    books on astrobiology, ‘Rare Earth’ and ‘The Life and Death

    of Planet Earth’ (Box 2).

    Box 1 Example topic areas in astrobiology.

    Star birth, death and recycling of elements

    Formation of planetary systems

    Origin and evolution of life

    Search for extraterrestrial biosignatures

    Habitable planets and satellites within and beyond our solar system

    Earth’s early geosphere, hydrosphere and atmosphere

    Earth’s early biosphere

    Mass extinctions and diversity of life

    Fossil and geochemical evidence of early life

    Life in extreme environments

    Planetary protection

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    Current Opinion in Biotechnology 2003, 14:347–354 www.current-opinion、com

    Astrobiology as an exciting new field for

    research

    In this brief article, it is not possible to provide detailed

    information about ongoing astrobiology research that is

    changing our views of our world and the possibility of life

    elsewhere. What I have done is to ask my colleagues to

    submit references of recent articles that they believe

    have made major contributions in their fields. I have

    grouped these below under various astrobiology subject

    headings along with brief descriptions of their content

    and significance. This is not meant to be a complete

    listing, but should provide an indication of the vitality

    and breadth of the field. An excellent general reference

    on astrobiology has been written by Des Marais and

    Walter [3].

    Extreme environments and extremophiles

    Several groups have looked at extreme environments on

    Earth, protracting their findings to possible conditions on

    other planetary bodies. For example, Doran and colleagues

    [4] report on Lake Vida, one of the largest lakes in

    the McMurdo Dry Valleys of Antarctica, which was previously

    believed to be frozen solid. However, it now turns

    out to contain a briny liquid (seven times seawater salinity,

    temperature below 108C) beneath a 19 m thick ice

    cover that has effectively isolated the brine for about 2800

    years. The ice cover contains microbial populations that

    are metabolically active upon thawing. The physical

    features and geological history of the lake suggest it

    may be an analog of the last vestige of an ancient Martian

    aquatic ecosystem.

    Similarly, Kelley and coworkers [5] describe a new class

    of marine hydrothermal system hosted on peridotites.

    The field hosts at least 30 active and inactive 30–60 m

    tall carbonate chimneys that vent fluids at 40–758C with

    pH values of 9–10. The chimneys harbor dense and

    diverse microbial communities. Because this system is

    hosted in peridotites, it is very reducing and associated

    with high pH fluids. It may be the best current analog

    to hydrothermal systems that operated on early Earth

    (Figure 1).

    Other groups have investigated various environments,

    including winter sea-ice [6] (Figure 2), active sulfide

    chimneys [7,8], and the acidic, iron-rich red river, Rio

    Tinto, in Southern Spain [9]. Together, these types of

    studies have highlighted the harsh environments in which

    life can exist and have helped scientists understand the

    range of environments outside Earth that may harbor

    microbial life.

    Geological sciences

    Sudbury in Ontario is the largest known and most important

    bolide impact structure (astrobleme) on Earth, being

    one of the first to be recognized and debated. Its many

    geological features are exposed at the Earth’s surface, and

    Box 2 Astrobiology book and journal list (since 2000).

    Textbooks

    Bennett J, Shostak S, Jakosky B: Life in the Universe. Boston:

    Addison Wesley; 2003.

    For introductory college courses for nonscience majors; stronger

    on the physical sciences than biology

    Goldsmith D, Owen T: The Search for Life in the Universe, 3rd Edn.

    San Francisco: Benjamin Cummings; 2002.

    For introductory college courses for nonscience majors; stronger

    on the physical sciences than biology

    Prather E, Offerdahl E, Slater T: Life in The Universe Activities

    Manual. Boston: Addison-Wesley; 2003.

    Student activities to accompany the textbook by Bennett et al.

    Zubay G: Origins of Life on the Earth and in the Cosmos, 2nd Edn.

    London: Harcourt; 2000.

    Tutorial approach to the biochemistry of how life works and its origin

    Popular books

    Clark S: Life on Other Worlds and How to Find It. New York:

    Springer-Praxis: 2000.

    Darling D: Life Everywhere: the Maverick Science of Astrobiology.

    New York: Basic Books; 2001.

    Well-written; includes personalities of researchers

    Darling D: The Extraterrestrial Encyclopedia: an Alphabetical

    Reference to All Life in the Universe. Three Rivers; 2001.

    deDuve C: Life Evolving: Molecules, Mind, and Meaning. Oxford UK:

    Oxford University Press; 2002.

    Nobelist argues for the inevitability of the emergence of life

    Dick S: Life on Other Worlds: the 20th Century Extraterrestrial Life

    Debate. Cambridge UK: Cambridge University Press; 2001.

    Shorter, popular version of ‘The Biological Universe’ listed below

    Fry I: The Emergence of Life on Earth: a Historical and Scientific

    Overview. New Jersey: Rutgers University Press; 2000.

    Excellent overview of past and current ideas on the origin of life

    Grady M: Astrobiology. Washington: Smithsonian Institution Press; 2001.

    Nice slim volume

    Koerner D, Levay S: Here be Dragons: the Scientific Quest for

    Extraterrestrial Life. Oxford UK: Oxford University Press; 2000.

    Ward P: Rivers in Time: the Search for Clues to Earth’s Mass

    Extinctions. Columbia: Columbia University Press; 2000.

    Ward P, Brownlee D: Rare Earth: Why Complex Life is Uncommon in

    the Universe. Copernicus, 2000.

    Pioneering synthesis; astronomer and paleontologist argue that planets

    with conditions for life more complex than single cells are

    rare in the Universe

    Ward P, Brownlee D: The Life and Death of Planet Earth: How the

    New Science of Astrobiology Charts the Ultimate Fate of Our

    World. New York: Henry Holt; 2003.

    Wills C, Bada J: The Spark of Life: Darwin and the Primeval Soup.

    Cambridge MA: Perseus; 2000.

    Scholarly publications

    Dick S: The Biological Universe: the Twentieth-Century

    Extraterrestrial Life Debate and the Limits of Science.

    Cambridge UK: Cambridge University Press; 2000.

    The definitive historical study of the development over the 20th

    century of ideas (both scientific and more popular, e.g. UFOs) on

    extraterrestrial life, origin of life, exobiology and astrobiology

    Horneck G, Baumstark-Khan C (Eds): Astrobiology: The Quest for the

    Conditions of Life. New York: Springer; 2002.

    Most chapters (by separate authors) are an outgrowth of a

    workshop on astrobiology held in Germany; uneven coverage

    Lemarchand G, Meech K (Eds): Bioastronomy ‘99: A New Era in

    Bioastronomy. Proceedings of the Astronomical Society of the

    Pacific Conference; Hawaii, USA, 2–6 August 1999. Vol. 213.

    ASP, 2000.

    Proceedings of a wide-ranging conference; strongest on the astronomy

    Journals

    Astrobiology. New York: Mary Ann Liebert, Inc.; (2001–).

    International Journal of Astrobiology. Cambridge UK: Cambridge

    University Press; (2002–).

    Astrobiology, the transcendent science Staley 349

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    it is one of the world’s largest sources of nickel ore. The

    Fe-Ni-Cu-S ore was not derived from the bolide, but

    formed by processes induced by the impact. Naldrett [10]

    has reviewed our current understanding of this site in an

    article that illustrates the contribution of the geological

    sciences to astrobiology.

    Planetary and atmospheric science

    Astronomers are beginning to discover planets beyond

    Earth’s solar system and new models are being proposed

    for their formation [11]. Data from the Hubble Space

    Telescope provided the first direct detection of the atmospheric

    composition of a planet orbiting a star outside our

    solar system [12]. Sodium was found in the atmosphere

    of a planet orbiting a yellow, Sun-like star called HD

    209458, located 150 light-years away in the constellation

    Pegasus. Although this particular planet is a gas giant like

    Jupiter and unlikely to harbor life, the study demonstrated

    that it is feasible to measure the chemical makeup

    of extrasolar planetary atmospheres and to potentially

    search for the chemical markers of life (such as O2)

    beyond our solar system [13].

    Recent evidence strongly supports the view that Mars has

    water that has flowed in the recent past, supporting the

    notionthat subsurface brinesmayexist [14].Bolideimpacts

    in the past may have thawed frozen subsurface water

    leading to temporary episodes of rain and flash floods [15].

    Earth may have actually frozen over completely in its

    past, a phenomenon referred to as ‘Snowball Earth’.

    Hoffman and Schrag [16] have recently reviewed this

    field and Warren et al. [17] discuss where surface life may

    have survived during one of these remarkable events.

    Until recently, atmospheric scientists explained how early

    Earth could remain unfrozen even when the sun was 30%

    less luminous because they believed the atmosphere had

    high levels of the greenhouse gas, carbon dioxide. This

    view has now changed as Pavlov et al. [18] showed how

    biogenic methane in an early anoxic atmosphere could

    have served as the key greenhouse gas. Catling et al. [19]

    showed that the high methane concentration in the early

    atmosphere could also explain the oxidation of the atmosphere:

    ultraviolet light’s decomposition of methane to

    hydrogen and its escape to space would have left Earth

    more oxidized before biogenic oxygen production.

    Early evolution

    As surprising as it may seem microbiologists are still

    discovering on Earth entirely new kingdoms ofmicrobial

    life including representatives from each of the three

    Figure 1

    Several groups have looked at extreme environments on Earth, protracting their findings to possible conditions on other planetary bodies. Kelley and

    coworkers [5] described a new class of marine hydrothermal system from the mid-Atlantic Ridge that is hosted on peridotites, which may be the

    best current analog to hydrothermal systems that operated on early Earth. The figure shows a hydrothermal vent off the coast of Washington State.

    The structures at this site vent at temperatures up to 3008C. Detailed analyses of one of the sulfide structures shows that they host dense and

    diverse microbial communities. (The photograph is reproduced with kind permission from D Kelley.)

    350 Science policy

    Current Opinion in Biotechnology 2003, 14:347–354 www.current-opinion、com

    domains, the Bacteria, Archaea and Eucarya. One example

    is described in the recent paper of Huber et al. [20]

    who reported an unexpected group of the Archaea,

    known species of which parasitize other members of

    the Archaea.

    Much confusion still exists about the evolution of the first

    organisms. Woese [21] considers the importance of horizontal

    gene transfer on the evolution of early cellular life.

    He proposed the ‘Darwinian Threshold’ as a seminal

    period that separates early evolution in which horizontal

    gene transfer dominated evolutionary processes from the

    subsequent period in which evolution followed the vertical

    inheritance of life as we now know it.

    Although evidence indicates that many of the traits of the

    Eucarya can be traced to the Bacteria and Archaea, until

    recently tubulin genes have only been found in the

    Eucarya, all species of which have them. However, this

    too is no longer true; a bacterium that contains a- and

    b-tubulin homologs has now been discovered [22].

    Paleontology

    Shen et al. [23] demonstrate the existence of microbial

    sulfate reduction as early as 3.45 billion years ago, providing

    the first evidence of a specific metabolism in

    Earth’s evolutionary record. As this is typically a heterotrophic

    metabolism in which organic matter is oxidized

    anaerobically with sulfate, it implies that microbial ecosystems

    were already quite diverse with complex trophic

    webs and biogeochemical cycles. As sulfate reduction

    requires sophisticated biochemical control, it further

    implies that soon after the end of heavy meteorite bombardment

    of the Earth, life was already quite advanced in

    its cellular functions.

    Considerable doubt has been cast on the claim that there

    is carbon-isotopic evidence for life on Earth older than

    3.85 Ga [24,25]. If correct, this claim would imply that

    autotrophic organisms inhabited the Earth at the time of

    the heavy meteorite bombardment and therefore that life

    could have been widespread in the early solar system. Van

    Zuilen et al. [24] argue that the observed carbon-isotope

    fractionation is not biotic, but is instead the result of

    metamorphic carbonate reduction to graphite. Fedo and

    Whitehouse [25] argue that the host rock for this graphite

    is an altered igneous rock and not a sedimentary banded

    iron formation, so it should not be expected to host

    biological remains.

    Planetary protection and the search for

    extraterrestrial intelligence

    Astrobiologists are concerned about the biological contamination

    of planetary bodies by life from elsewhere.

    Figure 2

    Sea-ice on Earth has become a model system in which to study planetary bodies such as Jupiter’s moon Europa, which has a frozen ocean that is

    shown in close-up view. The texture of the ocean supports the view that there are large blocks of ice floating on a liquid ocean that may support

    microbial life. (Figure reproduced with courtesy of the Jet Propulsion Laboratory at NASA/Caltech.)

    Astrobiology, the transcendent science Staley 351

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    Rummel [26] has written an accessible review of the

    history and state of planetary protection policy and implementation.

    More specific issues, such as the handling and

    quarantine of samples returned from elsewhere (e.g.

    Mars), have been considered in some detail [27].

    In part 1 of a comprehensive treatment of biological

    transfer, Mileikowsky et al. [28] discuss the potential

    for the natural transfer of microbes between solar system

    bodies. This is based on knowledge that large impact

    events (from comets or asteroids) occurring on one body

    can propel significant quantities of material off a planetary

    surface and into solar orbits that may intersect the orbits

    of other bodies.

    The search for extraterrestrial intelligence (SETI) continues

    as one of the earliest endeavors that has attempted

    to discover advanced life on other planetary bodies [29].

    NASA’s astrobiology website contains links to the NAI

    projects as well as an Astrobiology Roadmap that

    describes research goals. Perhaps what is most remarkable

    is that, during the past decade, this field has grown from a

    small core of dedicated scientists to a large and impressive

    group with many young scientists. With the emergence of

    new technologies, such as genome sequencing and extrasolar

    system planetary discovery techniques, our understanding

    in all areas from molecular evolution to planetary

    habitability is rapidly transforming our comprehension

    of astrobiology.

    Astrobiology’s promise for multidisciplinary

    science education and research

    Most educators agree there is a need to rethink science

    and engineering education. Many of the traditional disciplines

    seem to lack context in our modern world, at least

    to many young scholars. By incorporating astrobiology

    into a curriculum, the treatment of subject matter

    changes. For example, consider the biology instructor

    who is interested in teaching about the diversity of life.

    A typical approach would be to discuss the different

    species from each of the numerous animal groups and

    how some are being threatened with extinction due to

    habitat loss. In an astrobiology course the diversity issue

    could be addressed in the context of mass extinctions,

    such as, ‘What happened to the dinosaurs?’ The answer to

    this question entails a discussion of biology, paleontology,

    astronomy, physics (for dating fossils), evolution and

    could be followed up by a discussion of the human-driven

    mass extinction that is occurring now. Therefore, astrobiology

    can provide a compelling way of integrating the

    sciences in the classroom.

    Also, from a pragmatic standpoint, the subject matter in

    astrobiology is very flexible. It can be taught within the

    structure of an entire science curriculum at one extreme,

    or as a single course. Furthermore, astrobiology can be

    taught to all educational levels and it serves as an engaging

    outreach program to the public.

    Because of the interest in astrobiology courses, several

    books have recently been published, some of which could

    serve as textbooks for courses at the undergraduate and

    graduate levels (Box 2).

    Policy recommendations for astrobiology

    science education and research

    PhD traineeship programs

    Evidence from our University of Washington National

    Science Foundation (NSF) Integrative Graduate Education

    and Research Traineeship (IGERT) astrobiology

    program (http://depts.washington、edu/astrobio/) indicates

    that astrobiology can serve as an excellent subject area for

    interdisciplinary PhD education in science and engineering.

    Because astrobiology is such a broad and exciting

    field of study in science, it should be promoted as a

    curriculum in science education and research at the

    doctoral level.

    We recommend that NASA, NSF and other appropriate

    federal agencies should provide support for the implementation

    of PhD traineeship programs in science and

    engineering education in astrobiology. This will develop

    a unique group of scientists and engineers who will be

    able to effectively communicate and collaborate with one

    another. Furthermore, they will be able to subsequently

    train university students in astrobiology and interdisciplinary

    research.

    Astrobiology students who receive PhD degrees will be

    ideal candidates for the instruction of courses for doctoral

    students interested in astrobiology. At this time there are

    very few students. Even when more students graduate,

    however, it should be recognized that they will not have

    the in-depth experience to supervise students in PhD

    courses and research in areas outside their own disciplinary

    expertise, so a co-mentoring approach appears more

    appropriate. Astrobiology students trained in our program

    complete all of the necessary requirements in their major

    department and, in addition, complete the requirements

    for the astrobiology program. Therefore, they can compete

    effectively for post-graduate opportunities with

    others in their own area, but have the added experience

    of working in a multidisciplinary training environment,

    which, we believe, makes them better prepared for their

    future careers.

    Astrobiology PhD programs are likely to remain interdepartmental

    for the foreseeable future. Although they

    may eventually be accepted as departmental programs,

    this seems premature now as it may actually detract from

    the true vision of a cross-disciplinary field. Nonetheless, if

    life is discovered elsewhere in our solar system or in

    another planetary system, it could certainly lead to a need

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    Current Opinion in Biotechnology 2003, 14:347–354 www.current-opinion、com

    to train additional astrobiologists through university

    departmental programs. In this sense, an astrobiology

    training program could serve as a forerunner for the cadre

    of scientists and engineers eventually needed.

    The current NSF IGERT program is an excellent model

    to use for development of a joint NASA-NSF or other

    agency program, because of the importance it places on

    integrative student training and support for development

    of novel educational ideas.

    Undergraduate university level

    Astrobiology is currently amenable for the instruction of

    undergraduate students in single courses. Textbooks are

    available that may be used for that purpose if institutions

    have faculty members who can teach in the various

    subject areas.

    Because astrobiology covers such a vast area, most instructors

    will find it difficult to teach an entire course; however,

    it could be team-taught by faculty from biology and the

    physical sciences. Ultimately, as PhD scientists and engineers

    are trained in astrobiology, they would become

    ideal candidates to teach an entire course at the undergraduate

    level.

    Our recommendation for teaching astrobiology at the

    undergraduate level is to provide support for training of

    existing faculty at institutions that wish to develop astrobiology

    courses or a curriculum. This could be handled by

    supporting faculty study leaves to a university in which a

    graduate level program in astrobiology is in place, as well

    as at the various non-academic NAI institutions.

    Primary and secondary education

    Astrobiology is an exciting field that is ideal for teaching

    science to students in secondary education. Some materials

    are currently available for this such as Astro-Venture

    for grades 5–8, at the NAI site mentioned previously, and

    the SETI Institute high school curriculum (www.seti、org/

    Welcome.html). However, there is a need to train teachers

    and develop additional instructional materials. This

    could be initiated with a trial period at primary and

    secondary schools that wish to pursue this subject matter

    in their science curriculum. Once this trial period is over,

    say after five years, the concept could be evaluated and, if

    appropriate, implemented.

    To teach astrobiology at this level we recommend that

    support is provided for workshops and course planning

    sessions for scientists from universities with astrobiology

    programs and science teachers of primary and secondary

    school students. The goal of these workshops is to

    develop trial curricula for teaching astrobiology at the

    primary and secondary levels. It would also be necessary

    to support the development of astrobiology courses and

    appropriate educational materials (textbooks, videos,

    websites, etc) that could be used for teaching primary,

    secondary and undergraduate students interested in

    science and engineering.

    Conclusions

    Recent advances in scientific knowledge from such disparate

    areas as microbiology, astronomy, geochemistry,

    paleontology, genomics, planetary science and molecular

    evolution have culminated in the formation of the new

    field of astrobiology. Astrobiology, which transcends virtually

    all of the sciences, aims to answer the great questions

    about the origin of life and its distribution and

    evolution in the Universe. Astrobiology has quickly

    ascended to international prominence as a novel multidisciplinary

    and integrated scientific research area.

    Because of its innately interesting subject material, astrobiology

    is ideally suited for teaching science from kindergarten

    to the graduate level. Now is the time to

    implement astrobiology into educational programs in

    the form of new courses and new curricula. In order to

    accomplish this goal, governmental resources will be

    needed to train teachers and develop appropriate instructional

    guidelines and materials.

    Acknowledgements

    I want to thank my colleagues at the University of Washington who have

    made suggestions and provided some of the references mentioned,

    especially Roger Buick, David Catling, Eric Cheney, Jody Deming,

    Deborah Kelley, Marsha Landolt, Thomas Quinn, Steve Warren and Llyd

    Wells. In addition, I wish to thank David Morrison who provided the book

    listing and Woodruff Sullivan III who provided book annotations. Also

    thanks to Rosalind Grymes and John Rummel for their excellent

    suggestions, most of which I have adopted. I am also grateful to the NSF

    IGERT and NASA NAI programs for providing support for my laboratory’s

    research in astrobiology.

    References and recommended reading

    Papers of particular interest, published within the annual period of

    review, have been highlighted as:

    of special interest

    of outstanding interest

    1.

    Armstrong J, Wells L, Gonzalez G: Rummaging through Earth’s

    attic for remains of ancient life. Icarus 2002, 160:183-196.

    This paper suggests that the moon may contain fossils of early Earth

    organisms in rocks that were ejected to the moon by impacts.

    2.

    Wells L, Armstrong J, Gonzalez G: Reseeding Earth by impacts of

    returning ejecta during the late heavy bombardment. Icarus: in

    press.

    Since the moon probably received ejecta from early Earth, returning

    ejecta from the moon could have re-inoculated the Earth, which might

    have been sterilized by large impacts.

    3.

    Des Marais D, Walter M: Astrobiology: exploring the origins,

    evolution, and distribution of life in the Universe. Annu Rev Ecol

    Systems 1999, 30:397-420.

    Comprehensive review article with 100 citations of technical articles.

    4. Doran P, Fritsen C, McKay C, Priscu J, Adams E: Formation and

    character of an ancient 19-m ice cover and underlying trapped

    brine in an ‘ice-sealed’ east Antarctic lake. Proc Natl Acad Sci

    USA 2003, 100:26-31.

    5.

    Kelley D, Karson I, Blackman D, Fruh-Green D, Gee J, Butterfield D,

    Lilley M, Olson E, Schrenk M, Roe K: An off-axis hydrothermal

    field discovered near the Mid-Atlantic Ridge at 308N.

    Nature 2001, 412:145-149.

    This paper announces the discovery and describes the nature of the novel

    ‘Lost City’ hydrothermal vent system near the mid-Atlantic ridge.

    Astrobiology, the transcendent science Staley 353

    www.current-opinion、com Current Opinion in Biotechnology 2003, 14:347–354

    6.

    Krembs C, Deming J, Junge K, Eicken H: High concentrations of

    exopolymeric substances in wintertime sea ice: implications

    for the polar ocean carbon cycle and cryoprotection of

    diatoms. Deep-Sea Res 2002, 49:2163-2181.

    This study of winter sea-ice cores shows that the ice is filled throughout

    with high concentrations of exopolymeric substances (EPS). At winter-ice

    temperatures to as low as –208C, EPS were observed to protect organisms

    within the ice against physical damage by encroaching ice crystals.

    7. Schrenk M, Kelley D, Delaney J, Baross J: Incidence and diversity

    of microorganisms within the walls of an active deep-sea

    sulfide chimney. Appl Environ Microbiol: in press.

    A comprehensive, up-to-date treatment of the diversity of life within

    active sulfide chimneys. Fluorescence in situ hybridisation, 16S rDNA

    sequences and cell count data are provided in several transects/zones

    across the wall of a 3008C chimney from the Mothra Hydrothermal Field.

    8.

    Kelley D, Baross J, Delaney J: Volcanoes, fluids, and life in

    submarine environments. Annu Rev Earth Planetary Sci 2002,

    30:385-491.

    This major review paper looks at processes in the mantle to the hydrosphere

    in the context of impacts on microbial communities. Much of the

    information is directly relevant to astrobiological questions concerning

    the flux of volatiles, heat sources and linkages to microbial processes.

    This paper is being used by numerous upper undergraduate and graduate

    classes in a textbook fashion.

    9. Zettler L, Gomez F, Zettler E, Keenan B, Amils R, Sogin M:

    Eukaryotic diversity in Spain’s river of fire. Nature 2002, 417:137.

    DNA extracted from the acidic, iron-rich red river, Rio Tinto, in Southern

    Spain showed that 60% of its biomass is contributed by eukaryotic

    microorganisms. 18S rDNA sequencing indicated this extreme environment

    contains a surprising diversity of eukaryotic microorganisms.

    10. Naldrett A: Presidential address: from impact to riches:

    evolution of geological understanding as seen at Sudbury,

    Canada. GSA Today 2003, 13:4-9.

    11.

    Mayer L, Quinn T, Wadsley J, Stadel J: Formation of giant planets

    by fragmentation of protoplanetary disks. Science 2002,

    298:1756-1759.

    This planet formation article is causing a paradigm shift in the way we

    think of planet formation and has implications for the ubiquity of planetary

    systems.

    12.

    Charbonneau D, Brown T, Noyes R, Gilliland R: Detection of an

    extrasolar planet atmosphere. Astrophys J 2002, 568:377.

    This is the first report of an atmosphere of an extra-solar system planet.

    13. Des Marais D, Harwit M, Jucks K, Kasting J, Lin D, Lunine J,

    Schneider J, Seager S, Traub W, Woolf N: Remote sensing of

    planetary properties and biosignatures on extrasolar terrestrial

    planets. Astrobiology 2002, 2:153-181.

    14. Malin M, Edgett K: Evidence for recent ground water seepage

    and surface runoff on Mars. Science 2000, 288:2330-2335.

    15. Segura T, Toon O, Colaprete A, Zahnle K: Environmental effects

    of large impacts on Mars. Science 2002, 298:1977-1980.

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