The National Research Council’s solar system exploration decadal survey enunciated a comprehensive series of goals, priorities, and recommendations relating to the exploration of Mars.1 The decadal survey also described the important role played by R&A programs, technology-development activities, and related undertakings in supporting Mars missions. The following series of extracts from the decadal survey—relating to, for example, the recommendations for small, medium, and large spacecraft missions—are relevant to the topics discussed in this letter report.
While MSR cannot replace certain crucial in situ measurements (e.g., heat flow, seismicity, electromagnetic sounding for water, analyses of labile samples, and determination of atmospheric dynamics), it is scientifically compelling in its own right, and the ground-truth acquired from returned samples will aid the interpretation and greatly enhance the value of data from orbital and robotic lander missions. Spacecraft capabilities that would contribute to effectiveness in sampling include mobility, in situ reconnaissance analytical instrumentation, and a core drilling device. (Under current conditions, it appears likely that living organisms, and more generally all organic material, would be destroyed by oxidizing conditions in the surface layer of Mars. They may be preserved only at depth in the planet. Just what depth—centimeters, meters, kilometers—is unknown.) Necessary capabilities include the ability to manipulate and document samples collected and to package them in a way consistent with requirements placed by the planetary protection protocol imposed on the mission. A radioisotope power system for the mission … would expand the geographic range of sites that could be sampled and would extend the mission’s stay time, allowing the collection of a larger and more carefully selected suite of samples. Ample power undoubtedly will be important if drilling is contemplated.2
Observations by robotic orbiters and landers alone are not likely to provide an unambiguous answer to the most important questions regarding Mars: whether life ever started on that planet, what the climate history of the planet was, and why Mars evolved so differently from Earth. The definitive answers to these questions will require analysis in Earth-based laboratories of Mars samples returned to Earth from known provenances on Mars. Moreover, samples will provide the ultimate ground-truth for the wealth of data returned from remote-sensing and in situ missions. The SSE Survey recommends that NASA begin its planning for Mars Sample Return missions so that their implementation can occur early in the decade 2013-2023.