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Toward More Interaction Between the
NASA Astrobiology Institute and the
Planetary and Astronomical Sciences
Two space science activities, planetary science and the astronomical search for origins, have made and
continue to make strong intellectual contributions to astrobiology. Yet both of these disciplines, especially the
latter, are underrepresented in the Astrobiology program in general and in the NASA Astrobiology Institute (NAI)
in particular. In this chapter the committee explores this imbalance and makes recommendations for its rectifica-
tion.
PLANETARY SCIENCES AND ASTROBIOLOGY
Intellectually and programmatically balanced research programs within NASA have the greatest potential for
successful scientific output. The planetary science community, working within the context of NASA's Solar
System Exploration program, has achieved this balance after some decades of evolution. In the first decade of the
existence of planetary science as a distinct discipline (through about 1970), planetary scientists focused largely on
supporting the primary NASA effort in human exploration of the Moon. While other missions were conceived and
executed (e.g., the Mariner missions to Mars and Venus), most of the resources were expended on the Ranger,
Lunar Orbiter, and Surveyor spacecraft sent to the Moon. Much was learned about our nearest neighbor in space,
with perhaps the most spectacular results being the development of the impact origin of the Moon and the
realization that impact processes have played a fundamental role in planetary evolution.) However, the narrow
intellectual focus of NASA's planetary science activities made them vulnerable to the rise and fall of the Apollo
program, and lunar studies fell victim to the end of human lunar exploration.
In planetary science's second decade (through 1980), the Solar System Exploration program broadened
somewhat, but large resources were expended on the one goal of searching for life on Mars. While technologically
successful, the Viking missions of the mid-1970s cast a scientific pall on the exploration of Mars until the mid-
1990s, and in the late 1970s the agency found itself with a few large missions modeled, in scale at least, after
Viking.2 From 1980 through 1990, planetary science largely relied on these large missions, and consequent
delays, failures, or cancellation damaged the intellectual vigor of the field.
COEL argues that the situation today in planetary science is spectacularly different, and much healthier.
NASA's Solar System Exploration program includes a mix of flight programs, which run from Discovery missions
(e.g., Mars Pathfinder, Near-Earth Asteroid Rendezvous, and Stardust) through to flagship missions (e.g., Galileo
32
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NASA ASTROBIOLOGY INSTITUTE AND THE PLANETARY AND ASTRONOMICAL SCIENCES
33
and Cassini), and provides a varied tapestry of flight-preparation times, risks, and rewards. Notable among these
has been the spectacular exploration of the outer solar system, commencing with the Pioneer 10 and 11 missions,
through the Voyager discoveries about the satellite systems of the giant planets, and culminating in the Galileo
discoveries about Europa and the promise of Cassini discoveries at Saturn. Laboratory studies have blossomed as
well, because techniques developed to analyze the Apollo lunar samples have been applied to the large numbers of
meteorite samples found, serendipitously, through Antarctic exploration. Among these samples are pieces of Mars
and the Moon, and laboratory studies inspired the goal of directly collecting small-body samples that is being
realized through the ongoing Stardust mission. These direct samplings of primitive and evolved material in the
solar system, including organic phases, are being directly applied as well to the astronomical study of planetary
origins.
For over a decade, the astronomical studies have provided increasingly detailed information on planetary
systems in formation (from space-based platforms such as the Hubble Space Telescope [MST] and ground-based
systems such as the twin 10-m Keck telescopes). But perhaps most extraordinarily, the detection and now the
characterization of extrasolar planets has created a new intellectual realm within planetary science, and also has
produced profound synergies between observational planetary astronomy and its parental roots in large telescopic
observations of the cosmos. Giant planets are being detected indirectly and, in a few cases, observed directly to
allow analyses of their bulk and atmospheric properties. Flight opportunities ranging in scale from Explorer
(microlensing) through Discovery (Kepler-transits) to flagship (the Space Interferometry Mission [SIM]) missions
cannot truly be classified as astronomical or planetological because they are informed by both. Theoretical
understanding of planets gleaned from flight missions within the solar system is being applied successfully to
extrasolar planets, today in the realm of the giants, but eventually to terrestrial planets as well.
Indeed, for these reasons the planetary science activities today are so intellectually robust that the sudden
cancellation in 2002 of two outer planet missions (to Europa and Pluto) will cause much less disruption in the
program than it would have in the 1980s or 1990s.
Astrobiology has strong intellectual links with the planetary sciences that go well beyond the exploration of
two objects (Mars and Europa) to the investigation of diverse environments within which organic evolution has
transpired and extended to the origin of life itself. Several of the node principal investigators in the NAI are either
planetary scientists or individuals with a strong interest in the planetary sciences. A number of planetary scientists
are involved in other Astrobiology program elements, such as the Exobiology research and analysis program and
the Astrobiology Science and Technology Instrument Development program.
However, COEL believes that the relationship between astrobiology and the planetary sciences could be
better. The recent effort to produce a decadal strategy for planetary sciences exhumed deep suspicions within a
significant portion of the planetary community that astrobiology would dominate solar system exploration to the
exclusion of a balanced flight program, and that it would displace scientific priorities in planetary exploration not
having to do with the search for life. In part, this suspicion dates back to the 1970s with the strong Viking emphasis
on finding life on Mars at the expense of potential geophysical and geochemical explorations of the red planet.
Today, however, planetary science is so intellectually strong and broad that such concerns are unfounded, if NASA
continues to recognize the value and strength of a broad planetary program.
COEL believes that the broad planetology and astrobiology communities jointly have a responsibility to go
beyond shallow and polarizing characterizations of the two research areas to a much more extensive intellectual
and research relationship. This may require formal efforts to bring larger numbers of scientists together to explore
the intellectual connections more deeply than they have been explored to date.
COEL commends NASA for developing a strong and well-balanced Solar System Exploration program that
forms an important foundation for much of the central endeavor of astrobiology.
Recommendation
The NASA Astrobiology Institute should initiate a much broader suite of focus group programs with
planetary scientists, beyond those currently devoted to studies of Mars and Europa, to create a deeper level of
mutual understanding and appreciation of the two research areas and to provide new perspectives for future
solar system exploration.
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34
LIFE IN THE UNIVERSE
ASTRONOMICAL SEARCH FOR ORIGINS AND ASTROBIOLOGY
Astronomical Search for Origins, as a NASA program, comprises study of the formation and early evolution
of galaxies, stars, and planets. It has also come to include the detection and characterization of extrasolar giant
planets, leading eventually to the detection and characterization of extrasolar planets the size and nature of Earth.
The advent of space telescopes and large ground-based telescopes have enabled fundamental advances in these
areas. Key results include, for example, the following:
· Origin and evolution of galaxies, production of the biogenic elements, history of star formation rates,
. . .. . . . . .. . ... .. . .. . . . . . .. - · . . . . ~ . -
temporal and spatial changes in stellar metallicity, relationships between metallicity and planet formation and
habitability;4
· The relationship between star formation and the frequency of planet-forming disks;s
· The frequency of formation of giant planets and terrestrial planets;6
· Properties of extrasolar giant planets and their evolution via orbital migration;7
· Stability of planetary orbits and spin states as affected by gravitational perturbations from other planets and
from natural satellites over the history of planetary systems;8
· Elucidation of practical techniques for the detection and characterization of extrasolar habitable planets;9
and
· Understanding the chemical composition of molecular clouds, protostellar disks, and comets.~°
Research relating to the astronomical search for origins is incredibly fertile today, and one would be hard-
pressed to decide whether the most exciting results are being obtained on the largest (cosmological) or smallest
(planetary systems) scales. It is not an exaggeration to argue that the Copernican revolution is in fact being
completed today in the elucidation of the structure and fate of the cosmos, and in the determination of the
frequency with which planetary systems form and the nature of the worlds thus built. The astronomical search for
origins is also a programmatically healthy research area in the sense that discoveries are accomplished with a mix
of ground- and space-based facilities, which in turn involve projects both small (inexpensive) and large (expen-
. .
slve) In scope.
Millimeter-wavelength telescopes of 10- to 12-m diameter or greater are crucial in establishing the chemical
composition of comets, planetary atmospheres, and interstellar gas. Small ground-based optical telescopes 1 m
or less in aperture accomplished the first discoveries of planets around other stars and then their first characteriza-
tion by transits. These achievements required precise spectroscopic and photometric techniques developed in the
laboratory. The iodine gas absorption cells serving as a reference for the stellar wavelength shifts induced by
orbiting planets, and the precise photometry enabled by modern electronic detectors, transformed these modest
telescopes into major planet-detection and -characterization facilities. Much larger optical telescopes, with a
mirror aperture of 6 m or larger and equipped with advanced adaptive optics capabilities, are required to examine
the broader class of extrasolar planets that are not in the unusual orbital orientation necessary to make studies of
transit possible.
Such facilities, supported outside NASA with other federal, private, or state funds, represent a substantial
monetary contribution to the research area of astrobiology, on a level of hundreds of millions of dollars in
infrastructure. At the same time, existing or approved large-scale projects such as HST, the James Webb Space
Telescope (JWST), and SIM take such observations much farther in terms of precision and sensitivity. (The latter
mission is one component of NASA's so-called Navigator program, focusing on the detection and characterization
of extrasolar planets.) With HST, it has been possible not only to infer the size of an extrasolar giant planet by
means of transit photometry, but also to measure the atmospheric composition of the object.~3 JWST will take the
transit capability even farther. Moreover, SIM will enable detection and characterization of planets down to bodies
a few times the mass and/or size of Earth.
There are natural intellectual connections between studies in the general areas of the astronomical search for
origins and astrobiology. First, life as we understand it is a planetary phenomenon, and we seek its existence on
appropriate planets in orbit around other stars. Second, life is the culmination of chemical evolution that has
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NASA ASTROBIOLOGY INSTITUTE AND THE PLANETARY AND ASTRONOMICAL SCIENCES
35
transpired on cosmic time scales. Hence, the origin of the nonhydrogenic chemical elements including carbon in
stellar and galactic evolutionary processes leads naturally to organic chemistry in a variety of astrophysical
environments, and thence to the origin and evolution of carbon-based life in the free-energy-rich environment of
planet Earth. Indeed, in the NASA Astrobiology Roadmap, the astronomical search for origins and the astronomi-
cal techniques used to study them play strong roles.
Paradoxically, this is not the case programmatically within the Astrobiology program. Little astronomically
oriented research is conducted within the framework of the current Exobiology and Evolutionary Biology R&A
programs. Rather, this research fits more naturally within the Origins of Solar Systems R&A program. The latter
activity is comparable in size to the Exobiology program, and is administered under the Office of Space Science
but not from within the Astrobiology program. The technological-development programs (ASTID and ASTEP) are
devoted to techniques aimed at observing planets within the solar system or ecosystems on Earth, while the
separate Astronomical Search for Origins program focuses on developing new techniques for characterizing
extrasolar planets. The NAI itself has not been able to successfully centralize research teams devoted to the
astronomical search for origins in a meaningful way, with the exception of the node led by the University of
Washington, which was selected in the second round. Where NAI nodes have included astronomical studies
related to the search for origins as part of their research, this could be better integrated into and be a more important
part of the overall NAI effort. Part of the difficulty in doing so arises because little common ground exists between
the techniques and facilities that astronomers use to detect and characterize extrasolar planets and those familiar to
biologists. Further, there is a suspicion among a portion of the astronomical community that the usual difficulty of
assembling a peer-review panel for NAI membership that truly spans discipline breadth among biology, geology,
and astronomy may have served to rule out worthy proposals based on novel astronomical approaches to astrobio-
logical issues in the last competition for NAI membership.
ENHANCING INTERACTION BETWEEN ASTROBIOLOGY AND
THE ASTRONOMICAL SEARCH FOR ORIGINS
COEL sees a danger in attempting a forced realignment of the NAI toward the astronomical search for origins.
The natural center of gravity of the research at the NAI and its 15 nodes is not in astronomical studies relating to
origins, and it would be detrimental to the flow of research to do anything beyond collegial encouragement and
free exchange of ideas between astronomers and other disciplines in the NAI. However, the fertility of current
activities in the general area of the astronomical search for origins is exceedingly high. Moreover, public excite-
ment has been high over the discovery of new planets and what this foretells for the eventual discovery of Earth-
like planets. That research should not be forced into a different intellectual context simply for the sake of creating
an appearance of completeness in NASA's Astrobiology program itself.
COEL offers two suggestions for increasing the volume and value of interactions between scientists active in
the general areas of the astronomical search for origins and astrobiology. The first is to encourage the NAI and
major astronomical institutions to initiate joint study efforts, ranging from conferences to long-term focus groups,
that will enable more researchers in both areas to talk, mutually educate themselves, and "cross over" between the
disciplines. The Space Telescope Science Institute's conference Astrophysics of Life (May 2002) is an excellent
start to such an endeavor. It could be continued by initiating formal discussions, along the NAI's Mars and Europa
focus group models, exploring topics in, for example, "astrobiology and the astronomical search for origins." The
NAI and major astronomical institutions, recognizing the parity in research efforts between the two and avoiding
the impression that the NAI is trying to reinvent the astronomical wheel, should initiate such focus groups jointly.
The second suggestion, which is longer term, devolves from the fact that the NAI itself was intended to be
an experiment in the creation and operation of a virtual institute, whose outcome, if successful, would be the
propagation of such a structure to other promising fields of scientific endeavor. Astronomical studies relating to
the search for origins could be the next activity ripe for a consortium-based institution a NASA Origins Institute
(NOI) promoting research of scale, which is informed by and informs the large-scale ground- and space-based
programs now under way. The breadth of astronomical origins from the creation of galaxies to the formation and
early evolution of planets is a strength in this regard. It would contribute to the potential intellectual scope of such
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36
LIFE IN THE UNIVERSE
a new institute and to the level of competition that would be anticipated in the call for proposals for it. Arguing for
this approach is the current lack of consortium-based research opportunities in astronomical studies related to
origins on a scale larger than the individual R&A grants (typically $100,000 per year) and smaller than the flight
missions (typically $100 million or larger in total development cost, spanning several years or more). Finally, the
roadmap makes clear the intellectual and technical linkages among different problems and activities in the Astro-
nom~cal Search for Ongins program. An NOI would allow NASA to reap the benefits of these linkages by
encouraging and funding collaboration among multiple institutions with differing expertise in the full range of
studies relating to the astronomical search for ongins.
COEL recognizes the natural overlaps between the NAI and an NOI, particularly in the area of organic
chemistry and the origin of life. In the main, the areas and techniques employed in NAI and NOI research would
be complementary, not redundant. Creation of an NOI would be an acknowledgment of both the success of the
NAI and the need to maximize the scientific opportunities inherent in the astronomical search for ongins. It would
also extend the experiment of the virtual institute concept to address the important issue of interactions between
institutes. Could the NAI and an NOI foster additional and more meaningful interactions between the correspond-
ing fields?
Recommendations
· NASA should foster more extensive links between the Astrobiology and the Astronomical Search for
Ongins programs. In the short term, these linkages require cooperation between the NAI and major astro-
nom~cal institutions, such as the Space Telescope Science Institute and universities with extensive astronom~-
cal programs, in creating joint workshops and focus groups to educate researchers in both areas and to initiate
more extensive and novel research endeavors.
· Panels evaluating NAI membership proposals must be broadly constituted to ensure expert evaluation
of research programs that are intellectually strong but have a discipline balance very different from that found
in the existing NAI nodes.
· NASA should study the feasibility and desirability of creating and funding an institute, akin to the
NAI, dedicated to consortium-based science and technology (e.g., involving multi-institution teams) related to
the astronomical search for origins on the full range of spatial and temporal scales.
NOTES AND REFERENCES
1. K. Righter and R. Canup, Origin of the Earth and the Moon, University of Arizona Press, Tucson, 2000.
2. M.H. Carr and J.B. Garvin, "Mars Exploration," Nature 412: 250-253, 2001.
3. Space Studies Board, National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, National
Academies Press, Washington, D.C., 2003 (in press).
4. G. Gonzalez, D. Brownlee, and P. Ward, "The Galactic Habitable Zone I. Galactic Chemical Evolution," Icarus 152: 185-200, 2001.
5. C. Briceno, A.K. Vivas, N. Calvet, L. Hartmann, R. Pacheco, D. Herrera, L. Romero, P. Berlind, G. Sanchez, J.A. Snyder, and P.
Andrews, "The CIDA-QUEST Large-Scale Survey of Orion OB1: Evidence for Rapid Disk Dissipation in a Dispersed Stellar Population,"
Science 291: 93-96, 2001.
6. J.I. Lunine, "The Occurrence of Jovian Planets and the Habitability of Planetary Systems," Proceedings of the National Academy of
Sciences 98: 809-814, 2001.
7. G.W. Marcy, W.D. Cochran, and M. Mayor, "Extrasolar Planets Around Main Sequence Stars," pp. 1285-1311 in Protostars and
Planets IV, V. Mannings, S. Russel, and A.P. Boss, eds., University of Arizona Press, Tucson, 2000.
8. M.J. Duncan and T. Quinn, "The Long-term Dynamical Evolution and Stability of the Solar System," pp. 1371-1394 in Protostars and
Planets III, E.H. Levy and J.I. Lunine, eds., University of Arizona Press, Tucson, 1993.
9. C. Beichman, N.J. Woolf, and C.A. Lindensmith, The Terrestrial Planet Finder, National Aeronautics and Space Administration,
Washington, D.C., 1999.
10. A. Li and J.M. Greenberg, "A Comet Dust Model for the ~ Pictoris Disk," Astronomy and Astrophysics 331: 291-313, 1998.
11. E.F. van Dishoeck and G.A. Blake, "Chemical Evolution of Star-Forming Regions," Annual Reviews of Astronomy and Astrophysics 36:
317-368, 1998.
12. G.W. Marcy, W.D. Cochran, and M. Mayor, "Extrasolar Planets Around Main Sequence Stars," pp. 1285-1311 in Protostars and
Planets IV, V. Mannings, S. Russel, and A.P. Boss, eds., University of Arizona Press, Tucson, 2000.
13. D. Charbonneau, T.M. Brown, R.W. Noyes, and R.L. Gilliland, "Detection of an Extrasolar Planet Atmosphere," The Astrophysical
Journal 568: 377-384, 2002.
Representative terms from entire chapter:
planetary science
