Review of NASA Office of Space Science Enterprise Strategic Plan: Letter Report (2003)

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ASSESSMENT OF NASA’S DRAFT 2003 SPACE SCIENCE ENTERPRISE STRATEGY 6 (JIMO)—and the perception of this mission as a priority of the NRC’s SSE survey. According to the presentation by the chair of NASA’s Space Science Advisory Committee to the NASA Advisory Council on March 20, 2003, “This mission [JIMO] responds to the National Academy of Sciences’ recommendation that a Europa orbiter mission be the number one priority for a flagship mission in Solar System exploration.”14 Yet the science objectives of JIMO, as presented in the draft document, do not map clearly to the SSE survey’s Jupiter-system objectives. Furthermore, the Board has not yet seen a scientific review of the OSS’s proposed implementation of JIMO and thus has no basis on which to assess whether JIMO can achieve the science objectives recommended for the Europa Geophysical Explorer (EGE) mission. The Board understands that JIMO is the OSS’s response to an emerging budgetary and policy window of opportunity. Nevertheless it is concerned that, under the OSS draft document, the near- to mid-term exploration of Europa will become hostage to the successful implementation of an uncertain and expensive advanced technology development program. Given the uncertainties in mission design and cost, as well as the many other outer solar system missions that might utilize nuclear reactor technology to address important scientific priorities, NASA’s best near-term strategy may be to consider JIMO as one of several reference missions for establishing the requirements and guiding the development of advanced power and propulsion technologies until such time as JIMO’s responsiveness to the scientific priorities for the exploration of Europa and the other Galilean satellites can be assessed. INTERDISCIPLINARY ASPECTS AND SCIENTIFIC BALANCE The draft document discusses the scientific balance across themes and within theme areas. Section 4.1, Program Elements, describes the array of components that constitute the OSS program, including flight missions, research and analysis (R&A), sounding rocket and balloon programs, advanced detector and instrument systems, ground-based programs, laboratory measurements, supporting technologies, and data management. The draft also refers to interdisciplinary scientific aspects of the OSS program in individual theme sections and in the discussion on astrobiology, which is the most visible interdisciplinary activity in the program. Overall, the document offers a balanced description of science within and among themes. In the interest of strengthening the OSS program, the Board identifies several opportunities for enhancing the scientific balance among these elements and for highlighting additional interdisciplinary activities within the OSS portfolio. Balance Across Themes The Board appreciates NASA’s efforts to include the search for life as part of its NASA Vision and Mission, Section 2, page 6, but believes the emphasis is overstated under Goal 5, “Explore the solar system and the Universe beyond, understand the origin and evolution of life, and search for evidence of life elsewhere” and in the many repeated references to the search for life, sometimes without substance, throughout the document. This overemphasis minimizes science that is not focused on life and sometimes reduces 

ASSESSMENT OF NASA’S DRAFT 2003 SPACE SCIENCE ENTERPRISE STRATEGY 7 scientific credibility. To cite two examples, first the SEC theme refers to a link between biospheres and energy from the Sun but does not elaborate on how SEC will advance the agency strategic goal, “Understand the origin and evolution of life and search for evidence of life elsewhere” as presented on page 9. To retain a credible linkage between SEC and biospheric processes, examples should be provided. The document could discuss potential ultraviolet effects on atmospheric and ocean chemistry in the form of photolysis reactions that produce oxygen radicals and oxidized forms of sulfur. These reactions could have an important influence on life even in the absence of photosynthesis. Second, studies are under way to learn which “biosignatures”—identifiable spectral features in a planet’s reflected light—might reveal past or present life on a planet. However, to take advantage of this new information it will be necessary to develop space telescopes of unprecedented size and sophistication. The Board also believes that additional attention to identifying science and technology connections across themes, and more generally across the nation’s astronomical and Earth-oriented research, would strengthen the OSS draft document. For example, as pointed out in the NRC report Life in the Universe, there are linkages among Solar System Exploration, Mars Exploration, and Astrobiology as well as between Astronomical Search for Origins and Astrobiology,15 but none of those connections are explicit in the draft document and others are not mentioned. The Board did not find any mention in the document of the potential ties between the James Webb Space Telescope (JWST), which will explore the formation and evolution of planetary systems, and the Near-Earth Objects program or with other studies of the outer solar system. Another opportunity for strengthening the connection among theme discipline areas would be to describe the overlaps between studies of dark matter, neutrino masses, astrometry, and gravitational wave phenomena through the Wilkinson Microwave Anisotropy Probe (WMAP), the Solar Heliospheric Observatory (SOHO), and neutrino observatories. The OSS draft document should also provide a clearer connection between terrestrial climate, which is mentioned as a key area for the Living With a Star (LWS) program, and how this research is implemented within the broader NASA (Earth Science Enterprise) and national (e.g., Climate Change Research Initiative) contexts.16 The document generally achieves a consistent level of detail within the various theme sections, although the SEU theme was overly specific in its discussion of missions and mission details (box on page 46). In addition, one of the most profound astrophysical discoveries of the last decade was evidence for dark energy and the accelerated expansion of the universe, which are not yet explained in terms of fundamental physics and are noted as leading questions in the Connecting Quarks with the Cosmos report.17 This discovery is so important that the Board believes it deserves mention in the list of “grand questions” in the opening paragraphs of the SEU theme. The WMAP’s contribution to the exploration of dark energy could also be noted. The role of astrobiology is presented in the document in the box “Astrobiology and the Search for Life” (following page 9). However, the Board believes that the language in the box generally underestimates the complexity and difficulty of “understanding” how life originated and evolved. At best, scientists can “explore” or “investigate” the origins and evolution of life; claiming the goal of “determining or understanding” promises much more than basic science is likely to deliver.