on the need for and uses of nuclear power and propulsion systems. In addition to calling for the reopening of RPS production lines, both the SSE and SSP decadal survey reports recommended that NASA assign a high priority to the development of advanced propulsion systems, including NEP.4,5 The SSE decadal survey explicitly included NEP in its list of recommended technology developments, and it pointed to several missions that “are enabled or enhanced by NEP” and that naturally follow on from missions recommended as priorities for the decade 2003–2013.6 The 2001 AAp decadal survey makes no recommendations concerning the use of nuclear power and propulsion systems.

It was specifically not the task of the committee to reprioritize the decadal surveys, to set priorities for the period beyond the time horizons of the respective surveys, or to draft a formal review of Project Prometheus. But because the committee was charged to identify high-priority objectives, it used selection criteria that are broadly consistent with those used by the three most recent decadal surveys. That is, priorities are determined by consideration of intrinsic scientific merit and a combination of other issues, including technical readiness, programmatic balance, availability of necessary infrastructure, and budgetary impact.7

In practice, this approach implied that the committee’s primary task was the identification of a series of promising mission concepts to help define where the availability of space nuclear systems could have a major scientific impact. It also implied that a necessary secondary task was the identification of a variety of technological, programmatic, societal, and budgetary caveats that might impact the potential space science applications of nuclear power and propulsion systems. It is the committee’s hope that, these caveats aside, the conceptual missions discussed in this Phase I report will be studied by NASA and the wider scientific community and, if found to have sufficient merit and potential, will then be considered for prioritization in future decadal surveys.


Solar and Space Physics and Solar System Exploration

The material presented in Chapters 4 and 6 clearly demonstrates that the availability of nuclear power and propulsion technologies has the potential to enable a rich variety of solar and space physics and solar system exploration missions. A particularly exciting prospect for the solar system exploration community is the likely availability of a new generation of RPSs that will enable missions ranging from long-lived surface landers to deep atmospheric probes. Similarly, the solar and space physics community is intrigued by the possible uses of nuclear power and propulsion systems to enable complex, multidisciplinary exploration activities in the outer solar system and the local interstellar medium.

Of the various nuclear technologies considered, RPSs directly enhance or are enabling for missions identified as priorities for the coming decade in the SSP and SSE survey reports. RPSs can also enhance and enable missions mentioned in the respective survey reports that are likely to be candidates for consideration as priorities in subsequent decades.

These and additional mission possibilities exist, but because of the lack of detailed studies, it is not possible at this time to say whether or not these missions are uniquely enabled or greatly enhanced by nuclear power and propulsion systems. Rather, the discussions in Chapters 4 and 6 center on the identification of a number of promising mission concepts that could plausibly be enhanced or enabled by RPS technologies and/or NEP. The mission concepts selected by the committee as particularly promising include the following (in heliocentric order):

  • Solar Coronal Cluster—an NEP-class mission designed to deploy multiple RPS-powered subsatellites in the inner heliosphere to study the origins of space weather (see Box 4.2);

  • Long-Lived Venus Lander—an RPS-powered lander designed to conduct seismic and other observations on the surface of Venus for at least 1 month (see Box 6.1);

  • Long-Lived Mars Network—a network of RPS-powered probes designed to conduct seismic, meteorological, and other observations on the surface of Mars for an extended period (see Box 6.2);

  • Jupiter Magnetosphere Multiprobe Mission—an NEP-class mission designed to deploy multiple RPS-powered subsatellites to study the global dynamics of the jovian magnetosphere (see Box 4.4);

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