How does one define the boundary between astrobiology and astrochemistry in these examples? In the Exobiology program, it was decided that the proposals needed to make a clear connection between the carbon in interstellar space and its delivery to Earth in the form of cometary or meteoritic material. More generally, the parts of astronomy that are most relevant to astrobiology are those that might directly influence either the origin or later evolution of life. They include many different subjects and should be viewed not as being narrow but rather as being life-focused. By applying this principle in a reasonable manner, it should be possible to define the parts of astronomy that ought to be included in astrobiological research at the critical step when funding decisions are made. Intellectually, the sweep should be broader in order to encompass areas that, with work and insight, can be brought directly into the astrobiological enterprise.
Finding. Funding for astrobiology is limited, and the boundaries of the field are unclear; there is a risk that not all funds will go toward research topics that are justifiably “astrobiology.”
Recommendation. In funding decisions, NASA and other funding agencies should regard astronomical research as astrobiology if it is life-focused in plausible ways.
With these points of view in mind, the committee summarizes currently funded astronomical research at the NASA Astrobiology Institute (NAI) and in other NASA-funded astrobiology programs.
There is significant astronomical content in the research proposed or being done by the present NAI nodes; however, there is some potential redundancy since many subjects are treated or studied at multiple centers. The committee identified seven specific subject areas that are the focus of more than one NAI node:
Planet formation. Planetary formation is being investigated at seven NAI nodes: NASA Goddard Space Flight Center (GSFC), Penn State Astrobiology Research Center (PSARC), Carnegie Institution of Washington (CIW), the University of Colorado at Boulder (CU-Boulder), the University of Washington (UW), the University of Arizona (UA), and NASA Ames Research Center (ARC). PSARC is investigating how stellar metallicity (elements with atomic weight greater than that of helium) affects planet formation and the possibility of planets around white dwarfs. CIW is modeling planetary formation and works on the detection of extrasolar planets. CU-Boulder is proposing to study the evolution of protoplanetary disks into planets. UA will study planetary formation through observations of circumstellar disks, while ARC is studying planetary formation in the context of planet habitability. GSFC will simulate interstellar clouds and protoplanetary chemistry.
Biomarkers. The Virtual Planetary Laboratory (VPL) at NAI is exploring the possibility of detecting biomarkers (especially ozone) on planets around F, G, K, and M stars. The astronomical environment and the spectral characteristics and variability of the host star are important for this work. ARC will assess the prospects of survival of biospheres and the strategies to detect them. The Search for Extraterrestrial Intelligence Institute (SETI) looks for novel biosignatures—namely, signs of extraterrestrial technology.