Managing science-driven projects involve important differences with respect to other types of space missions. The main one is the character of science, exploring the unknown, that establishes how the final output is evaluated and thus the tools used to maximize it. For space missions supporting market-driven applications, the assessment of performance is clearly defined by the quality of the service provided and its added value. For space science missions, success is evaluated in terms of the advance of scientific knowledge, based on new discoveries and the tests of the laws of nature. The output can be facilitated but not fully predicted. Thus, performance has to consider initial science goals and the engineering requirements to achieve them but also, and most important, the preservation and maximization of the potential for unknown discoveries. The key indicator of the success of a space science mission is the quality and quantity of achieved scientific breakthroughs and discoveries. To optimize them, we need to consider the full mission lifecycle, from the mission definition through the development and its operations. In this paper, we discuss some management considerations to ensure and maximize the science output of a space mission over its whole lifecycle, from planning to operations. Specific elements are proposed to evaluate the results.