FIGURE 2.1 Examples of tweets providing ideas for a sustainable U.S. human-spaceflight program.

laws that allow NASA to focus on consistent long-term planning, investing in more research and development (R&D) directly applicable to prolonged human spaceflight journeys, selecting artists to be astronauts, building more significant partnerships with international and commercial entities, and creating a clear storyline of how robotic and human missions are moving NASA toward the goal of human settlement.

In addition to providing ideas, the tweets and white papers were useful to the committee in reviewing the set of historical rationales presented later in this chapter. All the rationales mentioned in this report were also mentioned frequently in the tweets and white papers. Notably, the survival rationale made a strong appearance in both the white papers and tweets.


One of the charges to the committee was to identify the enduring questions that describe the rationale for and value of human exploration in a national and international context. Implicit in that charge is the thought that identifying such enduring questions can help to ensure the continuity and sustainability of choices for the U.S. program in human spaceflight. To address that task, the committee concluded that it was necessary to examine and discuss the historical rationales that have been presented as the reasons for which such a program is needed and useful. This chapter addresses both the enduring questions and the rationales.

Implied in the committee’s charge was the expectation that the committee could find questions that would both deepen the rationales for human spaceflight and provide a long-term compass for the work, as perhaps certain deep-science questions have done for some fields of science. However, the committee, having examined the historic rationales (discussed below) often given for the program, found no new or deeper rationales and no questions that would suggest them. The rationales can be divided into five that the committee calls pragmatic and two that the committee calls aspirational. The pragmatic rationales are related to benefits to economic and technological strength, to national security and defense, to national stature and international relations, to education and inspiration of students and the general public, and to scientific exploration and observation. The two aspirational rationales are human survival and shared human destiny and aspiration (for exploration). Each rationale can be evoked by one or more questions. However, in the context of the more pragmatic rationales, the questions do not lead to motivation specifically for human programs as opposed to motivations for spaceflight and space exploration more generally, including both robotic and human ventures. Furthermore, although the questions are important and will continue to be important, they do not rise to the level that the committee considered was intended by the term enduring question.

The National Academies of Sciences, Engineering, and Medicine
500 Fifth St. N.W. | Washington, D.C. 20001

Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement