The recommendations and a brief rationale are given below. A detailed discussion is presented in Chapters 2 through 6 of this report.

Two recommendations are better characterized as general strategies rather than specific opportunities:

Recommendation: Strategy 1—Every opportunity should be seized to increase the breadth and detail in inventories of organic material in the solar system. As results accumulate, each succeeding investigation should be structured to provide information that will allow improved comparisons between environments. Analyses should determine abundance ratios for the following:

• Compound classes (e.g., aliphatic, aromatic, acetylenic);

• Individual compounds (e.g., methane/ethane);

• Elements in organic material (e.g., C/H/N/O/S); and

• The isotopes of elements such as C, H, N, and O.

Investigators should strive to interpret these results in terms of precursor-product relationships.

These objectives are broadly applicable and represent systematic steps toward addressing questions of biogenicity, lines of inheritance of organic material, and mechanisms of synthesis. With limited funds, returns from investigations like those proposed below (in “Selected Opportunities for Research ”) will move NASA more smoothly toward ultimate success. For example, the task group proposes that newer, more sensitive, and specific analytical methods be used for the analysis and reanalysis of carbonaceous chondrites. As these studies proceed and the results from flight experiments are obtained, it will become apparent which of these new techniques should be adapted to flight experiments. Moreover, the ground-based investigations of chondrites will pave the way for better analyses of returned samples, whenever they become available.

Recommendation: Strategy 2—Organic-carbon-related flight objectives should be coordinated across missions and structured to provide a stepwise accumulation of basic results. Some of the objectives that should be included in such missions are as follows:

• Quantitation of the amount of organic carbon present to ±30 percent precision and accuracy over a range of 0.1 parts per million to 1 percent;

• Repetitive analyses of diverse samples at each landing site;

• Comparability so that relatable data are obtained from a wide range of sites; and

• Elemental and isotopic analyses so that the composition (H/C, N/C, O/C, and S/C) is obtained together with the isotope ratios of all the carbon-bearing phases.

These recommended approaches to research will allow scientists to build an overview of the distribution of organic carbon in the solar system; provide information about heterogeneity at each location studied; and support preliminary estimates of relationships, if any, between organic materials at diverse sites.

The selected research opportunities were divided by the task group into three general categories based on the cost of the research and the time frame in which it could be undertaken. The recommended research is given by category below.