as heavily in human aspirations and eventual outcomes as hard calculations of cost and benefit. John Maynard Keynes memorably wrote that

a large portion of our positive activities depend on spontaneous optimism rather than material expectations.…Most probably, of our decisions to do something positive, the full consequences of which will be drawn out over many days to come, can only be taken as the result of animal spirits—a spontaneous urge to action rather than inaction, and not as the outcome of a weighted average of quantitative benefits multiplied by quantitative probabilities.1

Keynes was referring to the decisions of investors, but his observation could reasonably be applied to the academic and career choices of young students, the passion of scientists whose work produces technological and economic bounties of unforeseen character, and explorers venturing into a new frontier.

It is important to note that the logic of the call for white papers, tweets, and similar data inputs does not produce results that can be generalized; that is, they are not results from representative samples of any group or population. No conclusions may be drawn from them about opinions or perceptions of “the public,” nor can any estimates be made about trends or percentages of people who hold one opinion or another. What can be said is that the opinions, positions, and arguments communicated to the committee through those venues are valuable sources of ideas and perspectives that might not otherwise be captured through more traditional polling and sampling methods. Thus, they were useful in the committee’s deliberations and helped to ensure that it did not overlook points of view that might otherwise not be visible.

The committee reached out primarily to key influencers in the science and technology communities who maintain a moderate to high level of attention to space-related topics. Among the social structures that were contacted were science institutions, universities, professional organizations, blogs (for example, Boing Boing, io9, and Wired), and social media (for example, social media at NASA, Tim O’Reilly, and Science Friday).

Respondents to the call for white papers were asked the following questions:

  • What are the important benefits provided to the United States and other countries by human spaceflight endeavors?
  • What are the greatest challenges to sustaining a U.S. government program in human spaceflight?
  • What are the ramifications and what would the nation and world lose if the United States terminated NASA’s human spaceflight program?

Almost 200 white papers were submitted to the committee in response to the call for input.2 Many came from people who were deeply engaged with NASA’s work and contributed thoughtful analyses of specific issues that they believed the committee needed to be better informed about. All were read by two or more committee members, and the committee devoted time to discussing what they had read and to point out important papers for the full committee to read. Ideas that made a strong appearance in the white papers included substantially increasing support and recognition of commercial spaceflight efforts, exploiting space for economic benefits, increasing international partnerships, and increasing focus on technology development.

Participants in the Twitter campaign were asked to answer the following question: What are your best ideas for creating a NASA human spaceflight program that is sustainable over the next several decades? Over a period of 27 hours, tweets and retweets that used the hashtag #HumansInSpace were captured and reviewed.3 The Twitter campaign captured 3,861 tweets and retweets, which came from 1,829 unique users who had a collective 13.75 million followers. Tweets related to the promotion of the campaign itself and all retweets were filtered out. About 1,604 original tweets from 710 unique users directly answered the call for ideas.

Many of the 1,604 tweets provided unique ideas on how to pioneer a sustainable human spaceflight program (Figure 2.1). Ideas that appeared often in the tweets included increasing the frequency of crewed missions, making


1 J.M. Keynes, The General Theory of Employment, Interest and Money, Book 4, Palgrave Macmillan, 1936, Chapter 12, Section 7, p. 161.

2 At the time of this writing, these can be viewed at

3 Access to the public discussion via Twitter was available at the committee’s website at

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