Planetary science transcends national boundaries. Even during the depths of the Cold War, planetary scientists from both East and West frequently cooperated by exchanging samples from their respective lunar missions or by coordinating their independent missions to Halley’s Comet. Now, decades later, planetary science is a truly global endeavor. Spacecraft that explore the planets come not only from the United States, but also from China, India, Japan, and the nations of Western Europe. If the list is expanded to include nations with some space-based capacity—those that use spacecraft data, build spacecraft instruments, operate relevant ground-based facilities, or contribute in some other way to the advancement of planetary science—planetary science encompasses the globe.

This chapter reviews the recommendations of the 2003 planetary science decadal survey and summarizes some of the most exciting recent scientific achievements. The chapter concludes with a discussion of the organization of this report, articulating how this and subsequent chapters relate to the the statement of task (Appendix A) for the Committee on the Planetary Science Decadal Survey.


In the 1970s and 1980s, science strategies for exploring the solar system were drafted by the National Research Council’s (NRC’s) Committee on Planetary and Lunar Exploration (COMPLEX), which addressed separately the inner planets, the outer planets, and primitive bodies. Early in the 1990s, COMPLEX crafted a single solar system strategy that united and updated the several preexisting documents. The resulting report, An Integrated Strategy for the Planetary Sciences: 1995-2010,1 showed that it was both feasible and appropriate to establish a set of self-consistent, solar-system-wide priorities for planetary science. The Integrated Strategy provided the foundation upon which the planetary community’s first decadal survey was built, with the process starting in 2001. Unlike the precursor reports from COMPLEX, which only considered science goals, the 2003 decadal survey—New Frontiers in the Solar System: An Integrated Exploration Strategy—both outlined science priorities and identified new initiatives needed to address those priorities.2 The study also advocated the creation of a new class of medium-size missions, named New Frontiers.

The 2003 decadal survey’s statement of task from NASA called for prioritized missions binned in small, medium, and large categories with respective costs of less than $325 million, less than $650 million, and more than $650 million in then-year dollars. That survey prioritized Mars missions separately from missions to other solar system destinations. The present report provides status updates for the missions recommended in the 2003 survey.

Non-Mars Mission Priorities in 2003


In the 2003 planetary science survey the only large mission identified was Europa Geophysical Explorer: a spacecraft to orbit Europa and determine the nature and depth of the subsurface ocean postulated to exist beneath Europa’s ice shell. Although much planning has occurred, the mission has not been initiated. Current efforts focus on implementing this mission in the context of a joint NASA-ESA Europa Jupiter System Mission (Chapters 8 and 9).


The 2003 planetary science decadal survey identified five medium-class initiatives to collectively initiate the competitively selected line of New Frontiers missions. These initiatives were, in priority order:

1. Kuiper Belt-Pluto Explorer—a mission to perform the initial spacecraft reconnaissance of the Pluto/Charon system as well as one or more other Kuiper belt objects. This mission is currently being implemented as the New Horizons mission launched in 2006 and scheduled to reach Pluto in 2015 (Figure 1.1). Subsequently, the spacecraft will be redirected so that it passes near to at least one additional Kuiper belt object, as was recommended in the 2003 planetary science decadal survey.

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