The National Research Council’s (NRC’s) decadal survey New Frontiers in the Solar System established an ambitious and comprehensive set of science objectives for solar system exploration.¹ In the present midterm review, the Committee on Assessing the Solar System Exploration Program evaluates the progress being made in addressing these objectives, assessing NASA’s mission portfolio, concept studies, research and analysis programs, Earth-based observing programs, and supported laboratory science, and the degree to which each has addressed the decadal science objectives. For each science objective, the committee provides a grade based on current progress toward the science objective, along with an indication of the trend in progress foreseen over the remaining 5 years of the period (2003-2013) covered by the decadal survey. (The grades and trends are defined in Chapter 1.)

Overall, NASA is making impressive progress toward many of the decadal survey science goals, with continued gains foreseen over the next 5 years. NASA’s Mars program in particular has been highly successful, with a comprehensive and detailed plan of investigations aimed at high-priority science objectives. Also, tremendous progress has been made in understanding the primitive, nonplanetary bodies in the solar system. The committee gives this area a grade of B.

Despite its evident importance, however, NASA has not significantly addressed the primary goal of astrobiology (life detection), and progress toward other objectives has been slowed by the steep reduction in astrobiology research and analysis funding. Also, although it is beyond the horizon of the decadal survey, the committee notes that there is a large and growing gap between missions to the giant planets once the Juno mission (currently scheduled for launch in 2011) is completed. Because of these reductions, the committee debated assessing the area of meeting the science goals of the decadal survey as having a downward trend, but concluded that “No change” is more appropriate for now.

As presented in Summary Table S.1, the crosscutting themes of the decadal survey form the titles of the sections below, and each key question is shown together with the grade and trend for activity in that arrea as assessed by the committee.