The Future of Human Spaceflight: Objectives and Policy Implications in a Global Context

Why Fly People into Space?

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David A. Mindell, Scott A. Uebelhart, Asif A. Siddiqi, and Slava Gerovitch
Reconsidering the Rules of Space

To answer these questions, we must return to the basic objectives of human spaceflight and reexamine them in light of today’s world. For such a highly technical endeavor as spaceflight, its objectives have sometimes been surprisingly imprecise. What is the rationale for a large, government-funded program of human space exploration? With the rapid growth in robotic and autonomous systems, does the equation for human versus remote exploration require rebalancing?

Nations have sent people into space for a variety of reasons in the past fifty years. Some reasons have become obsolete in the face of changing technology; others remain salient for the future. Wernher von Braun’s original notion for a space station, for example, utilized human beings in orbit to change the film on space telescopes. Electronic imaging sensors and down-linked imagery have not only made film in orbit obsolete but have also replaced the need for human eyes in orbit as imaging tools.18 Early in the space era, military and intelligence agencies sought to use human spaceflight for their needs because, “given the state of robotic technology at that time, nearly every military use of space . . . was thought to need human operators at the site.”19 However, the military and intelligence communities have shown no firm interest in human orbital operations since the 1980s. During the Cold War, President Kennedy justified the expenditure of funds to send human beings to the Moon for “international political reasons” and stated that “the only justification for [the Apollo program] . . . is because we hope to beat [the Soviets] and demonstrate that starting behind, as we did by a couple of years, by God, we passed them.”20 Though the Cold War context has receded, human spaceflight is still partly justified by international prestige.

The recent Bush vision gives a representative mix of reasons for human spaceflight: to search for habitable worlds away from Earth, possibly leading to the discovery of present or past life on other planets; to develop new technologies; to inspire children to study and seek careers in science, technology, engineering, and math; and to symbolize American democracy to the world. Other objectives given for human beings in space include national security, scientific discovery, and establishing human colonies on other worlds, often for the purpose of saving the human race by seeding other planets.21

Each of these objectives does partially justify human spaceflight. Human spaceflight inspired, for example, many of today’s scientists and engineers across multiple disciplines who witnessed the Apollo program as children. But which objectives apply uniquely to human spaceflight? What objectives might be achievable with remote spaceflight programs or with other types of technology projects on the ground? For example, if the government wishes to support technology development, it could do so in more direct ways, such as research and development (R&D) contracts or direct funding of institutions. Similarly, might the billions spent on space exploration be spent in other ways to support math and science education on the ground? (By comparison, the National Science Foundation’s entire FY2008 budget for education in math, science, and engineering was a small fraction of NASA’s human spaceflight budget.22)

Primary and Secondary Objectives

We argue that the goals of a human spaceflight program should satisfy three criteria:

  1. They should only be accomplishable by human presence.
  2. They should have benefits that exceed the opportunity costs.
  3. They should be worth the risk to, and loss of, human life.

To structure goals around these criteria, we introduce the ideas of primary and secondary objectives. Primary objectives are those that meet the above criteria; they can be accomplished only through the physical presence of human beings, have benefits that exceed the opportunity costs, and are worthy of significant risk to, and possibly the loss of, human life.

By contrast, secondary objectives have benefits that accrue from human presence in space but do not by themselves justify the cost or the risk. Secondary objectives include science, economic development and jobs, technology development, education, and inspiration.

Consider science in this framework. None doubt that there are situations where people can accomplish tasks that machines cannot or that there exist things that machines can do only more slowly than people and with greater difficulty. For example, the situational awareness necessary to walk on a planetary body and identify geologic formations of scientific interest may still exceed the abilities of remote rovers. But few argue that the ability to accomplish field geology is by itself sufficient justification for missions costing tens or hundreds of billions of dollars. Were human beings to walk on Mars, they could accomplish significant science and make potentially revolutionary discoveries. But science alone does not justify human missions to Mars: the estimated cost would be many times the total budget of the National Science Foundation. Therefore, science is a secondary objective of human spaceflight.

Similarly, if human beings are to travel in space for long distances and durations, then it is ethically imperative to understand the biomedical implications for those travelers of prolonged exposure to space and planetary environments. This entails understanding the biomedical impact of the microgravity environment of the ISS and during transit to distant destinations, and of the reduced gravity environments on the Moon (1/6g, or one-sixth the gravity of Earth) and on Mars (3/8g). But such reduced- or microgravity life science research cannot be intrinsically justified; it is only necessary if we choose to send human beings into space for other, primary reasons.

Understanding the influence of gravity on biological systems also has implications for health on Earth. Here on Earth, medical experimentation with human beings is given serious ethical scrutiny, and practical limitations are enforced, no matter how great the potential benefit of violating those limitations. Human spaceflight purely for health research would likely be subject to simi-lar ethical constraints. Thus, human life-science research is also a secondary objective of human spaceflight.

Technology and economic development have a similar status. First is the opportunity cost; if the U.S. government wishes to invest in technology, it can do so in other, more direct ways. Developing space-based life-support technologies or Moon-dust scrubber systems, for example, are not as likely to generate returns for Earth-based applications as would direct investment in solar cell manufacturing or new biomaterials.

Another argument frames human spaceflight as a jobs program, one that employs tens of thousands of people on the ground. The shuttle program, for example, employs over two thousand civil servants and fifteen thousand work-year equivalents for contractors. But, again, few argue that human spaceflight is the only or even the optimal way to invest in a technically talented workforce. Dividing the cost of the shuttle program by the number of people employed yields a very expensive jobs program.

Given the current state of technology, no known natural resources in space can profitably be exploited. Even if researchers were to discover such resources and develop efficient extraction schemes to exploit them, human presence would not likely be required. Human presence will always be more expensive than remote operations, so any genuine space-based extractive business is likely to rely heavily on remote presence. Therefore, technology and economic development are secondary objectives of human spaceflight.

None of this is to say that secondary objectives are unimportant. All have contributing roles to play in justifying government expenditures on space exploration. While secondary objectives may or may not justify their own costs, we argue that, in general, they do not justify the risks to human life.

Primary Objectives: Exploration

Human spaceflight is risky. Seventeen people have died aboard U.S. spacecraft and four aboard Russian craft. One in sixty space shuttle flights has ended in disaster. What objectives have sufficient value for nations and cultures that justify these risks?

A primary objective of human spaceflight has been, and should be, exploration. Exploration is a keyword in the Bush vision and in NASA’s own terminology. Yet while the word is often used, it is rarely specified beyond lofty rhetoric and allusions to curiosity and frontiers. What is exploration, and why explore?

First, it is worth considering what exploration is not. Some argue that “exploration is in our DNA,” that some fundamental, even genetic, human trait compels us as individuals and as nations to seek out new territory. The civilization that fails to expand geographically, the argument goes, will enter a state of permanent decline, always to be superseded by other nations with more compelling wanderlust.

We reject these arguments about essentialist qualities of human nature. No historical evidence, no social science evidence, and no genetic evidence support an assertion that human beings have an innate, universal compulsion to explore geographically. In addition, space exploration is radically different from the kinds of geographical expansion that have marked human history because of its high degree of technical difficulty, the extreme hostility of the space environment to human life, and the lack of possible encounters with other human cultures. Furthermore, if some grand universal compulsion caused us to explore, we would find no compelling reason for the United States or any other nation to act now, because eventually we would migrate to the stars, regardless of our potentially fallible political decision-making. “There is nothing predestined about geographic discovery, any more than there is about a renaissance, a tradition of Gothic cathedrals, or the invention of the electric light bulb.”23

The exploration of space will continue if and only if governments or other large entities consider it within their interests and means to do so. “Perception of acceptable risk is not merely a calculation of probabilities, costs, and benefits; it is also a cultural choice and always subject to reconsideration.”24 Only a fraction of nations has ever found exploration valuable, and only a smaller fraction is now spacefaring. “Just because individuals like to explore does not mean that the larger group of which they are a part (in this case, the human race) has a need to collectively explore.”25

Moreover, if exploration were simply a matter of finding out what lies beyond our immediate vicinity, then satisfying that curiosity would not require direct human presence; that is, it would not satisfy the criteria for human spaceflight. If we are primarily concerned with finding what is out there, then robotic spacecraft and other technologies can search at a fraction of the cost and risk. In fact, many such machines are returning wondrous data every day. Even if an innate human curiosity is accepted as a justification for space exploration in general, it fails as a justification for human space exploration.

What, then, is exploration? Exploration is a human activity, undertaken by certain cultures at certain times for particular reasons; it has components of national interest, scientific research, and technical innovation but is defined exclusively by none of them.26 We define exploration as an expansion of the realm of human experience—that is, bringing people into new places, situations, and environments, and expanding and redefining what it means to be human. Exploration in the context of space activity addresses a number of key questions, such as: what is the role of the Earth in human life? Is human life fundamentally tied to the Earth? Could it survive without the planet?

Human presence, and its attendant risk, turns a spaceflight into a story that is compelling to large numbers of people. Exploration also has a moral dimension because it is in effect a cultural conversation on the nature and meaning of human life. Exploration by this definition can be accomplished only by direct human presence and may be deemed worthy of the risk of human life. “Ships [of discovery] must voyage into a moral universe that explains who a people are and how they should behave, that criticizes and justifies both the sustaining society and those it encounters.”27

As an example, the lasting impact of the Apollo program is not defined by specific technologies of interest to engineers or even by scientific results known within a particular community. What made an impression on people across the globe were images of human beings walking on another world. The feat stands as one of the notable moments in the 20th century. The photograph of Apollo 11 astronaut Buzz Aldrin on the Moon is a global icon of modernity and peaceful technological achievement. Even today, interest in Apollo centers on the human experience, as evidenced by the recent film In the Shadow of the Moon, which showcased the Apollo astronauts’ personal stories.28 The twelve men who walked on the Moon did something—experienced something —that no other people have done before or since. They expanded the realm of human experience.

Primary Objectives: Pride and Prestige

The expansion of human experience might seem too universal to satisfy national interests, too general to appeal to practical policy considerations. Indeed, the Apollo missions were undertaken “in peace for all mankind.” Nevertheless, they were unmistakably branded as American, and that branding provided the major political impetus for the program.29 Apollo expanded what it meant to be human in uniquely American ways. Observers hailed American astronauts as paragons of self-reliance, individualism, and other American virtues.30

Closely related to the exploration objective, then, are those of national pride and international prestige. Rockets and spacecraft are powerful symbols, and since its origins human spaceflight has been promoted and received as an indicator of national strength and purpose. During the Cold War, the Soviet Union and the United States upheld human spaceflight as the badge of national leadership, technological strength, and political resolve. Astronauts risked their lives in demonstration of these ideals, just as soldiers and airmen risked their lives to demonstrate the military strength of the nation. Lyndon B. Johnson perhaps put it best when he said, “In the eyes of the world first in space means first, period; second in space is second in everything.”31 By this argument, any nation advanced and focused enough to send people into space must be positioned to define the future. Any nation that could muster the resources, master the technologies, and exhibit the long-term commitment to mount human missions into space must be capable of other great feats, be they military, economic, or cultural.

Though the Cold War rivalry has faded, its presumption that leadership in space is correlated with economic, political, and cultural leadership has had wide impact. As many observers have noted, human spaceflight is an instrument of soft power; it serves as an example for members of other nations and cultures to emulate and follow. Incorporating this logic as their own, other nations have accepted the notion that human spaceflight is a marker of modernity and first-class status. In China and Japan, not to mention numerous other nations that have flown people on American or Russian flights, astronauts remain public figures of iconic “rock star” status. When Russian president Vladimir Putin wrote to Chinese president Hu Jintao after the first Chinese human spaceflight, he congratulated him on the “successful advancement of your country along the path of comprehensive development, of its becoming a modern world power.”32 The statement might have seemed condescending had it not validated the underlying objectives of the Chinese program.

All nations do not share the same objectives for human spaceflight, but each defines its human space accomplishments according to its own cultural values. Russian space enthusiasm, for example, reflects a history of philosophical, cultural, and religious musing on spaceflight.33 During the Soviet era, Soviet cosmonauts were hailed as ideological icons of the Communist regime:

Soviet propaganda often used the Soviet space program as a symbol of a much larger and more ambitious political/engineering project—the construction of communism. Both projects involved the construction of a new self, and the cosmonaut was often regarded as a model for the “new Soviet man.” The Soviet cosmonauts publicly represented a communist ideal, an active human agency of sociopolitical and economic change.34

The Chinese similarly acclaim their astronauts, or yuhangyuan (also referred to as “taikonauts” in the Western press), as embodiments of Chinese history, culture, and technological prowess:

If the particular types of heroic iconography that have come to surround China’s first space traveler, Shenzhou V’s Yang Liwei, [are] any sort of reliable indicator, Chinese society by 2003 was well on its way toward successfully mixing a rising sense of pragmatic nationalism, communist ideology, traditional Confucian values, and drive for economic and high-tech industrial competitiveness into an effective recipe for an expansive program of human spaceflight.35

In India, too, accomplishments in space represent national aspirations to become a global power.

By sending people into places and situations unprecedented in human history, nations aim to expand a global definition of humanity in their own image. Former NASA administrator Mike Griffin expressed this sentiment from the American point of view, stating, “I would like to be assured that wherever the frontier of human civilization is, that people from America are there as well. . . . [Space exploration] should be viewed as an investment in carrying American culture, American values.”36 The benefits to a country being represented in this way have generally justified the risk and cost of human life, much as military service to a nation is deemed worthy of such sacrifices.

Public perceptions of spaceflight vary among nations. For rising countries such as China and India, “space exploration represents one of a constellation of important ways with which to announce their ‘arrival’ as global powers,” and it serves to announce their emergence into an elite club of spacefaring powers.37 Despite variations in the political systems of countries undertaking space exploration, they tend to focus on similar lists of “justifications.”

Americans, more secure in recent decades of their nation’s leadership in science and technology, seem to be less interested: few Americans can name a single active astronaut. American public perception could change quickly, however, in the face of foreign accomplishments (a Chinese landing on the Moon, for example), or in light of continued declines, whether real or perceived, in U.S. fortunes and status.

National pride and international prestige achieved by physical human presence remain primary objectives of human spaceflight, and are deemed by nations to be worth the financial cost and risk to human life.

Risk and Resources

Descriptions of spaceflight routinely include the extreme hazards of the space environment: the amount of energy released during launch to accelerate spacecraft to orbital velocities (over 17,000 miles per hour); the orbiting spacecraft’s exposure to vacuum; and the extreme temperatures that the vehicle must withstand upon reentry. Since the beginning of the space age, all of these have been mitigated with technical solutions, but the failure of a technical system could still lead to catastrophic results. The risks associated with the space environment cannot be eliminated, only avoided.

We define inherent risks as those intrinsic to the activity of human spaceflight itself. By contrast, programmatic risks are introduced by human organizations, often because of faulty management, broken safety cultures, or insufficient resources. The history of spaceflight has shown that organizational stresses, whether budgetary or schedule-driven, coupled with high mission expectations can lead to compromises in vehicle design or operations, with potentially tragic consequences. We posit that Americans are willing to accept risks in exploration but only if those risks are clearly explained and represent the inherent risk of the endeavor rather than the programmatic risks imposed by a large organization struggling with inadequate resources, overconfidence, or other dysfunction.

The authors of the CAIB report note that the Challenger and Columbia accidents were caused by “failures of foresight” as much as by specific technical problems. These failures were not caused by a budget shortfall but resulted when, “in response to White House and Congressional mandates, NASA leaders took actions that created systemic organizational flaws.”38 The accidents occurred in environments of programmatic risk. Any development program makes choices, implicit or explicit, about the balance between risk (to performance, schedule, or human life) and available resources—choices with potential long-term implications for safety. Because these risks are programmatic, not inherent, they can be mitigated by policies and resources.

Even before the 2008 financial crises and economic downturn, NASA was struggling to find the resources to fulfill the Bush vision. Since the Bush vision was announced in 2004, the agency has taken on additional responsibilities beyond those in the vision (for example, the repair mission to the Hubble Space Telescope and an additional shuttle flight to launch a science payload), and has also experienced increased costs and unexpected expenses, all of which erode the funding for the Bush vision. This imbalance might already be causing the agency to overextend itself in an effort to meet unrealistic goals. NASA is currently being tasked to develop new systems and to maintain prominent programs while working to meet the objectives of the vision and trying to minimize the gap in U.S. human spaceflight capability.

Furthermore, the agency is constrained by the “go as you can afford to pay” policy. Soon after the Bush vision was announced, the Congressional Budget Office estimated NASA’s budget needs through the proposed Moon landing to be $32 billion more than the projected allocation.39 As a 2006 National Research Council (NRC) report described the situation:

NASA is being asked to accomplish too much with too little. The agency does not have the necessary resources to carry out the tasks of completing the International Space Station, returning humans to the Moon, maintaining vigorous space and Earth science and microgravity life and physical sciences programs, and sustaining capabilities in aeronautical research.40

Similarly, a 2008 NRC report expressed deep pessimism that the Bush vision could be sustained because “neither the [Bush] administration nor Congress had sought the resources that would be required to accomplish the Vision.” Of particular concern was that “resource shortfalls in budgets to support the development of new exploration systems integral to the Vision are having major disruptive impacts on other parts of NASA’s programs.”41

How will the current political environment—including the upcoming gap in U.S. launch capability, the need to rely on the Russian Soyuz, and the pressing economic situation—influence the development process? Will it create budget shortfalls or a rush to launch, and what will be the resulting risks? The CAIB report remarks how “the past decisions of national leaders—the White House, Congress, and NASA Headquarters—set the Columbia accident in motion by creating resource and schedule strains that compromised the principles of a high-risk technology organization. . . . We cannot explore space on a fixed-cost basis.”42 Programmatic risks should be acknowledged, even in the midst of an economic crisis, by policy-makers defining the future of the human spaceflight program.


18. Roger D. Launius and Howard E. McCurdy, Robots in Space (Baltimore: Johns Hopkins University Press, 2008).

19. Ibid., 6.

20. “Presidential Meeting on Supplemental Appropriations for NASA, November 21, 1962,” in John F. Kennedy Presidential Library, Boston; quoted in Robert C. Seamans, Jr., Project Apollo: The Tough Decisions (Washington, D.C.: NASA History Division, 2005), 45.

21. Roger D. Launius, “Compelling Objectives for Spaceflight? History and the Search for Relevance,” in Critical Issues in the History of Spaceflight, ed. Steven J. Dick and Roger D. Launius (Washington, D.C.: NASA History Division, 2006).

22. National Science Foundation, “President Signs Omnibus Appropriation Bill,” January 8, 2008,

23. Stephen Pyne, “Seeking Newer Worlds: An Historical Context for Space Exploration,” in Critical Issues in the History of Spaceflight, ed. Dick and Launius, 18.

24. J. R. McNeill, “Gigantic Follies? Human Exploration and the Space Age in Long-Term Historical Perspective,” in Remembering the Space Age, ed. Steven J. Dick (Washington, D.C.: NASA History Division, 2008), 8.

25. Taylor E. Dark III, “Reclaiming the Future: Space Advocacy and the Idea of Progress,” in Societal Impact of Spaceflight, ed. Dick and Launius, 570.

26. Daniel F. Lester and Michael Robinson, “Visions of Exploration,” Space Policy 25 (forthcoming).

27. Pyne, “Seeking Newer Worlds,” 18.

28. In the Shadow of the Moon, DVD, directed by David Sington (2007; Los Angeles: THINK-Film LLC, 2008).

29. Michael L. Smith, “Selling the Moon: The U.S. Manned Space Program and the Triumph of Commodity Scientism,” in The Culture of Consumption: Critical Essays in American History, 1880–1980, ed. Richard Wightman Foz and T. J. Jackson Lears (New York: Pantheon, 1983).

30. Howard McCurdy, Space and the American Imagination (Washington, D.C.: The Smithsonian, 1999).

31. Walter A. McDougall, “Technocracy and Statecraft in the Space Age—Toward the History of a Saltation,” The American Historical Review 87 (4) (1982): 1025.

32. Igor’ Lisov, “Yang Liwei in Space,” Novosti kosmonavtiki, no. 12 (2003), (in Russian).

33. Asif Siddiqi, The Red Rockets’ Glare: Spaceflight and the Soviet Imagination, 1857–1957 (New York: Cambridge University Press, forthcoming).

34. Slava Gerovitch, “‘New Soviet Man’ Inside Machine: Human Engineering, Spacecraft Design, and the Construction of Communism,” OSIRIS 22 (2007): 135.

35. James R. Hansen, “The Great Leap Upward: China’s Human Spaceflight Program and Chinese National Identity,” in Remembering the Space Age, ed. Dick, 119.

36. “NASA’s Griffin: ‘Humans Will Colonize the Solar System,’” The Washington Post, September 25, 2005,

37. Asif A. Siddiqi, “National Aspirations on a Global Stage: Fifty Years of Spaceflight,” in Remembering the Space Age, ed. Dick, 17–35.

38. CAIB Report, 195.

39. Congressional Budget Office, A Budgetary Analysis of NASA’s New Vision for Space Exploration (Washington, D.C.: Congressional Budget Office, 2004),

40. National Research Council, Review of NASA Plans for the International Space Station (Washington, D.C.: National Academies Press, 2006); emphasis in original.

41. National Research Council, United States Civil Space Policy: Summary of a Workshop (Washington, D.C.: National Academies Press, 2008), 11.

42. CAIB Report, 203.