NASA's Cosmochemistry Program is a highly interdisciplinary effort focused on studying materials from extraterrestrial bodies. Much of what we know about the origin and early evolution of solar system bodies, including the Earth, derives from analyses of the chemical, isotopic, and mineralogic compositions of meteorites, lunar rocks and soils, interplanetary dust particles, and presolar grains, as well as numerical and experimental simulations of the formation of precursor grains and the accretion and differentiation of such bodies. In addition to continuing studies of samples in hand, the Cosmochemistry Program will play a central role in curating and analyzing samples to be returned from asteroids, comets, and Mars by planned spacecraft missions.

   In describing mission-oriented research by NASA and similar government organizations, a National Science Policy endorsed by the House Committee on Science¹ recommended that "research and development in federal agencies, departments, and the national laboratories should be highly relevant to, and tightly focused on, agency or departmental missions, and must focus on essential programs that are well managed, long-term, high-risk, non-commercial, and have great potential for scientific discovery." How does the Cosmochemistry Program relate to NASA's mission?

   NASA's Space Science Enterprise Strategic Plan² identifies seven fundamental questions that form the basis for the agency's scientific mission. Below are listed some examples of major, ongoing Cosmochemistry research efforts that directly relate to each of these questions:

• Cosmic elemental and isotopic abundances based on analyses of primitive meteorites provide ground truth for galactic chemical evolution models, from which hydrogen and helium isotopic abundances critical for cosmological models can be calculated.

• The abundances of actinide nuclei deduced from analysis of planetary materials are major constraints on the rates of galactic r-process nucleosynthesis and the age of the galaxy.

How do galaxies, stars, and planetary systems form and evolve?

• Astrophysical models of stellar evolution are constrained by analyses of stardust grains extracted from chondritic meteorites.

• Interplanetary dust particles derived from comets provide information on the relative proportions of presolar and solar matter in comets and on the fate of volatiles and organic matter in the early solar system, and refractory inclusions in meteorites reveal how solid matter first condensed.

• The timing and mechanisms of planetary accretion and differentiation are defined by isotopic measurements, laboratory experiments, and numerical models of the formation of lunar samples and meteorites.

What physical processes take place in extreme environments?

• Melting and recrystallization in the deep interiors of planets and asteroids are understood by studies of samples from differentiated bodies, and can be simulated by laboratory experiments at elevated pressures and temperatures.

• Processes in an exploding supernova can be seen in particles of stardust that are ejected into the interstellar medium and later incorporated into meteorites.

How and where did life begin?

• Proposed chemical biomarkers, microfossils, and tiny minerals formed by organisms in a martian meteorite, while controversial, have prompted additional research which will be the basis for a Mars exploration program focused on the search for life.

• The apparent absence for evidence of life in organic-bearing meteorites from small asteroids that contained liquid water for short periods of time reveals that the emergence of life is not automatic.

How is the evolution of life linked to planetary evolution and to cosmic phenomena?

• The formation and evolution of the molecular building blocks of life in interstellar clouds and in the solar nebula are revealed by the compositions of organic molecules extracted from meteorites.

• Analyses of the abundance and isotopic composition of water in martian meteorites relates to the climate and habitability of Mars in the past.

• Impacts of large meteoroids, as documented by study of terrestrial impact rocks, have had disastrous biologic consequences.

How and why does the Sun vary and how do the Earth and other planets respond?

• The history of the Sun is written in the isotopic compositions of analyzed solar particles implanted in the regoliths of the Moon and other airless bodies.

• Present theories of terrestrial planet atmospheric evolution depend heavily on data derived from the study of solar particles in lunar soil.

How might humans inhabit other worlds?

• Knowledge of surface materials and how to utilize them is a prerequisite for establishing a base on any planet, e.g. analysis of lunar soils and volcanic deposits suggests possible use in oxygen production and as building materials.

• Continued habitation of our own world might depend on understanding the physical properties of a near-Earth asteroid on a collision course.

   NASA's mission involves both active exploration by spacecraft and unraveling the meanings of these discoveries through scientific research. The Cosmochemistry Program obviously contributes to scientific research, but it also has many direct connections with current and planned spacecraft missions:

• A primary goal of the Near-Earth Asteroid Rendezvous mission is to determine the relationship between meteorites and asteroid 433 Eros.

• Lunar Prospector has provided compositional maps which can be compared with mineralogical data from Apollo samples and lunar meteorites.

• Isotopic analysis of samples of the solar wind returned by the Genesis mission will test cosmic abundances inferred from chondritic meteorites.

• Cometary dust and interstellar dust returned by the Stardust spacecraft will be compared with interplanetary dust particles and with interstellar grains extracted from meteorites.

• Instruments on Mars Surveyor orbiters have been calibrated with martian meteorites, and their data may be interpreted in the context of these samples.

• Mars Surveyor lander missions will focus on the search for life, prompted in part by studies of the ALH84001 meteorite.

• The properties of martian meteorites can be used to leverage global results from a Mars sample return.

• Laboratory analysis of an asteroid sample returned by the Muses-C mission will provide ground truth for the calibration and interpretation of asteroid spectra.

   Although the Cosmochemistry Program is central to spacecraft missions that are expected to return extraterrestrial samples, it also unravels the secrets of materials derived from places where no spacecraft could ever go:

• Presolar grains extracted from meteorites were originally formed from atoms crafted by nuclear processes inside red giant stars and supernovae.

• Processes and conditions that occurred in the solar nebula or deep within the melted interiors of small planetesimals during the formative period of our solar system can be understood by studying meteorites.

• Laboratory experiments simulate core formation, crust extraction, and planetary outgassing.

   To extract the information in extraterrestrial materials, cosmochemists must analyze them using every technique at their disposal.

• Observations of the structures and compositions of crystals and amorphous materials, and the textural relationships between them, are made using optical and electron microscopes.

• The elemental, molecular, and isotopic compositions of materials are analyzed using a variety of tools, including electron and ion microprobes and mass spectrometers.

• Experiments are performed to understand the conditions under which various components are stable and to simulate the processes that have affected them.

• Terrestrial analogs are studied, since the conditions under which they formed may be better constrained.

   Laboratory analyses are inherently of higher quality than analyses performed in situ on the surfaces of another planet, an asteroid, or a comet. Many analytical techniques require significant sample processing in the laboratory before any measurement is made, and other measurements require such great sensitivity that equivalent spacecraft-mounted instruments simply cannot be constructed. Moreover, with samples analyzed in a laboratory, the experiments can be modified as new information is obtained.

   Extraterrestrial samples, whether obtained by spacecraft or by cosmic accident, are precious, so the quantities available and allocated for analysis are usually very small. Consequently, research in the Cosmochemistry Program challenges, and often leads, technology. The development of new micro-analytical capabilities and techniques, or in many cases even the acquisition of existing state-of-the-art instrumentation, offers a major challenge to the investigators in this program. NASA is considering the Laboratory Instrumentation for Analysis of Returned Samples (LIFARS) program, which can directly address this issue.

   Sample curation is critical to the Cosmochemistry Program's research, because extraterrestrial materials must be stored, handled, and processed in an environment that minimizes contamination and in a way that preserves materials for future research using techniques that have not yet been developed. The curation requirements for samples returned by spacecraft missions are likely to be very different from those employed for the continuous stream of recovered Antarctic meteorites and interplanetary dust particles. Several planned sample return missions are making use of existing Program curation facilities and expertise, already functioning at a high level of cleanliness and procedural maturity. However, modest investments in upgrades and adaptations will be required.

   Much of the successful cosmochemistry research depends on bringing together scientists from different disciplines, often accomplished by establishing consortia to study specific samples. Thus, the Cosmochemistry Program depends on breadth.

   The information gained from cosmochemical research is directly relevant to sample return missions, but it also complements information from other kinds of inquiry. For example, understanding the martian core depends not only on constraints on its size from Mars Pathfinder tracking telemetry but also on inferences about its composition from studies of martian meteorites, laboratory experiments, and numerical calculations. Determining whether asteroids are re-accreted "rubble piles" is based on density estimates from spacecraft observations of asteroid size and mass and on mineralogic studies of meteorite breccias which experienced radically different cooling rates. Documenting changes in the Sun's luminosity requires the integration of astrophysical theory with the measured isotopic compositions of the ancient solar wind implanted into lunar soil and modern solar wind particles returned by the Genesis spacecraft.

   Research in the Cosmochemistry Program is carried out by approximately a hundred principal investigators, primarily at universities and NASA field centers. There is constant tension between the desirability of integrating new investigators into the Program and the maintenance of established laboratory facilities to respond to mission requirements. This core discipline relies on analytical instrumentation and laboratory experiments. In many cases, off-the-shelf technology is not adequate for working with small extraterrestrial samples, so researchers in this Program must often develop specific protocols and specialized instruments. This has led to a tendency toward continuing commitments to highly productive, established research programs. The continuation of productivity and innovation is assured by the requirement of full peer review every three years. Many innovative research efforts, which require substantial periods of time to mature and involve considerable risk to the PI relative to the reapplication of previously successful approaches, permit discoveries that would be impossible without long-term support. For example, the identification and isolation of presolar diamonds in meteorites, which required more than a decade of effort at one laboratory, has allowed the emergence of one of the most exciting, interdisciplinary avenues of research in the space sciences.

   The National Research Council's recent report, Supporting Research and Data Analysis in NASA's Science Programs³, noted that the average grants in NASA Space Science disciplines have decreased in size during the decade ending in 1995. Their recommendation was that grants be monitored to ensure that funding levels are adequate to achieve the proposed research and that numbers of grants to an investigator are consistent with time commitments. The major scientific accomplishments of the Program in the face of declining funding over the past several decades are a tribute to the talents of Program scientists. However, the need to add new investigators at adequate funding levels, as noted above, competes with the need for appropriate funding for continuing, high-quality investigations. Some combination of on-going research programs and new initiatives is necessary to keep the Cosmochemistry Program vibrant. Program management must also consider diversification in terms of new skills needed. For example, sedimentary rocks may be prime targets for Mars sample return, based on the likelihood that they might contain organic matter or evidence for life, but no sedimentologists and very few organic geochemists or geobiologists are represented in the present Cosmochemistry Program.

   An accompanying figure gives an estimated time line for opportunities to study new extraterrestrial materials. The demographics of investigators in the Cosmochemistry Program will undergo significant changes during this time, and new laboratory facilities will be needed for these new investigators, prompted by advancing technology.

   Scientists funded by the Cosmochemistry Program have made astonishing discoveries, but with some notable exceptions these discoveries have not been communicated widely to the public or incorporated into K-12 curricula. Although cosmochemists publish their results in scientific journals, in reality their work is not complete until it has been communicated, in plain language, to the public which supports their research. This is not a difficult assignment. Space science seizes the public's attention and captivates its imagination, if scientists will make the effort. Cosmochemists have also not been conscientious enough about explaining the scientific importance of sample studies to colleagues in other fields of space science. To make informed decisions about future missions, we must ensure that all planetary scientists appreciate the value of laboratory studies.

This time line illustrates the expected recoveries of extraterrestrial samples by future spacecraft missions, against a backdrop of an ongoing Antarctic meteorite program and aircraft recoveries of interplanetary dust particles.

   Recommendation:

• Establish and fund the proposed Laboratory Instrumentation for Analysis of Returned Samples (LIFARS) Program. This is the highest priority recommendation of the MOWG.

CHALLENGE:
Develop and maintain the curatorial capability to maximize scientific return from all extraterrestrial samples.
   Sample curation involves processing and allocating materials for research and display, as well as protecting these precious samples for use by future generations of scientists. Each of the planned sample return missions will impose special curation requirements. The influxes of new samples are in addition to the steady stream of recovered Antarctic meteorites and interplanetary dust particles that also require curation.

   Recommendation:

• As soon as possible, develop and implement a plan for capable, cost-effective curation (and, as necessary, quarantine) of all samples returned by spacecraft missions. This should include a clear statement for the scientific desirability of widely distributing samples for analysis on a timely basis and a mechanism for international allocation of samples based on scientific merit.>/b>

CHALLENGE:
Strengthen and diversify the Cosmochemistry research community.
   Years of nearly constant funding have hindered the entry of investigators into the Cosmochemistry Program at adequate funding levels and discouraged potential graduate students and postdocs from entering the field. Sample return missions will, in many cases, occur after a significant number of current investigators have retired. New skills and expertise will be needed to attack the problems posed by these samples. At present funding levels, the need for a dynamic program, with changes in personnel to allow for shifts in scientific emphasis, is not compatible with the requirement to invest in upgraded laboratory facilities and long-term research efforts.

   Recommendation:

• Encourage new and under-represented investigators, as well as established scientists from outside the Cosmochemistry community, to become familiar with critical research issues and opportunities by involving them in NASA review panels and committees.

• Establish and maintain a Cosmochemistry Program web site that will attract wide interest and will include links to sites that provide information on new opportunities for researchers, graduate students, and postdocs.

• Add new areas of expertise (e.g. sedimentology, geobiology), which will be required by Mars sample return. An augmentation of investigators and funding is required to maintain current program balance and breadth, because multiple samples from different kinds of bodies will be returned nearly simultaneously.

• Provide access to interdisciplinary analytical facilities and support for such facilities.

• Increase opportunities for the next generation of cosmochemists by providing traineeships.

CHALLENGE:
Develop additional bridges to other space science communities.
   Cosmochemistry research is, by its very nature, interdisciplinary, and the Cosmochemistry Program has been particularly successful in building bridges to the fields of astrophysics (through studies of interstellar grains), planetary geology and geophysics (through studies of lunar rocks and experimental petrology), and exobiology (through studies of ALH84001) over the last decade. The opportunity to analyze new kinds of extraterrestrial materials, such as solar wind, cometary dust, and martian soil, will open new avenues of collaborative research.

   Recommendation:

• Explore and support new interdisciplinary initiatives, including programs jointly sponsored by other agencies. Important initiatives can be identified at workshops that encourage interdisciplinary research.

CHALLENGE:
Expand the collection of scientifically important samples at low cost.
   Ongoing collection and curation efforts (supported jointly, in the case of Antarctic meteorites, by NASA, NSF, and the Smithsonian Institution) have paid handsome dividends in new discoveries of previously unrecognized kinds of extraterrestrial materials. These "poor man's spacecraft missions" are highly cost effective.

   Recommendation:

• Continue aggressive collection and analysis programs for Antarctic meteorites and interplanetary dust particles.

CHALLENGE:
Effectively communicate the scientific basis for sample study to the broader scientific community and the excitement of new results in cosmochemistry to the general public.
   Education and outreach efforts are an important part of NASA's mission, and the Cosmochemistry Program must strengthen its efforts in these areas. The justification for an appropriately funded Cosmochemistry Program depends on communicating its discoveries to the rest of the scientific community and to the public.

   Recommendation:

• Include information appropriate for students in the Cosmochemistry Program's web site.

• Encourage Cosmochemistry investigators to publish outreach articles in magazines and web sites to increase visibility of the program.

• Support efforts to train scientists to communicate with journalists more effectively.

• Continue to produce and distribute multi-media materials to Cosmochemistry investigators to support their education and outreach activities.

• Explore reporting mechanisms for assembling media stories on Cosmochemistry Program research and for using this information in communicating with NASA administrators.

CHALLENGE:
Maintain the Cosmochemistry Program's strong relevance to NASA's strategic plan and its responsiveness to appropriate recommendations by advisory groups.
   As NASA's goals evolve, the Program must change.

   Recommendation:

• Ensure that the Cosmochemistry Program's NRA (and hence its funded research) directly addresses evolving NASA goals and conforms to appropriate recommendations from NRC and other advisory bodies.