Since the retirement of the space shuttle, the U.S. space community has been collectively wringing its hands over the state of the nation’s human spaceflight program. Hardly a day goes by without some commentary on possible directions for human spaceflight. At Congress’s behest, the National Academies’ Committee on Human Spaceflight is beginning to assess the goals of NASA’s human spaceflight program. This comes on the heels of another National Academies study on NASA’s strategic direction, the report just issued that places emphasis on the human spaceflight enterprise. In addition, a new report by the Space Foundation, “Pioneering: Sustaining U.S. Leadership in Space,” seeks an alteration in NASA’s mission to focus on human pioneering of space and eliminating tasks that do not emphasize that objective.

Whether these efforts will provide a way forward beyond the quagmire in which human spaceflight is presently caught remains to be seen. That all of them take as a given that human spaceflight must continue — or even be emphasized beyond its current status — seems assured. But should this be the case? James Van Allen famously asked in 2004: “My position is that it is high time for a calm debate on more fundamental questions. Does human spaceflight continue to serve a compelling cultural purpose and/or our national interest? … Risk is high, cost is enormous, science is insignificant. Does anyone have a good rationale for sending humans into space?”

Ascertaining what rationales for human spaceflight are compelling remains a core issue before the United States in the second decade of the 21st century. From the defining event of Sputnik in 1957, I would contend that there have been five major rationales that have been used effectively to justify a large-scale spaceflight agenda:

  • Scientific discovery and understanding.

  • National security and military applications.

  • Economic competitiveness and commercial applications.

  • Human destiny/survival of the species.

  • National prestige/geopolitics.

Specific aspects of these five rationales have fluctuated over time but they remain the core reasons for the endeavor that have any saliency whatsoever. The first three, at least thus far, have not required human activities in space. Those have been accomplished with lesser cost and arguably greater efficiency using robotic spacecraft, thank you very much. That may change in the future — conceivably this could happen as a military human spaceflight mission emerges — but at present these goals do not require humans in space. This might also change in response to the rise of space tourism, a major venture that envisages hotels in Earth orbit and lunar vacation packages. While this has yet to find realization, it remains a tantalizing possibility for this century.

The human destiny rationale for spaceflight has been used repeatedly by astronauts and others, emphasizing that an integral part of human nature is a desire for discovery and understanding. At one level, there exists the ideal of the pursuit of abstract scientific knowledge — learning more about the universe to expand the human mind — and exploration of the unknown will remain an important aspect of spaceflight well into the foreseeable future. It propels a wide range of human efforts to explore the Moon and beyond projected for the 21st century. It also energized such efforts as the Hubble Space Telescope, which has revolutionized knowledge of the universe since its deployment in 1990. Clearly, this goal also motivates the scientific probes sent to all of the planets of the solar system.

But most importantly, this idea has privileged human spaceflight as the raison d’être of human destiny for the long term. With the Earth so well known, advocates argue, exploration and settlement of the Moon and Mars are the next logical step in human exploration. Humans must question and explore and discover or die.

There is also a terrifying aspect to this rationale; humanity will not survive if it does not become multiplanetary. The apocalyptic aspect of this — a “survival of the species” argument — might be true, but it is also terrible to consider. Carl Sagan wrote eloquently about the last perfect day on Earth, before the sun would fundamentally change and end our ability to survive on this planet. While this will happen billions of years in the future, any number of catastrophes could end life on Earth beforehand. The most serious threat is from human-caused destruction, but an asteroid or meteor could also impact the Earth. Throughout history, asteroids and comets have struck this planet, and a great galactic asteroid probably killed the dinosaurs when an object only 10 to 15 kilometers in diameter left a crater 300 kilometers wide in Mexico’s Yucatan Peninsula.

Finally, national prestige and concern for geopolitical relations have dominated so many of the spaceflight decisions that it sometimes seems trite to suggest that it has been an impressive rationale over the years. Yet there is more to it than that, for while all recognize that prestige sparked and sustained the space race of the 1960s we too often fail to recognize that it continues to motivate support for NASA’s programs. The United States went to Moon for prestige purposes, but it built the space shuttle and embarked on the space station for prestige purposes as well. Prestige may make likely that no matter how difficult the challenges and overbearing the obstacles, the United States will continue to fly humans into space indefinitely, but this is not a certainty.

Now we are at a crossroads, and the question that Van Allen asked — does anyone have a good rationale for sending humans into space? — deserves serious consideration. Should human spaceflight be continued as a national program? Is it an appropriate course for the nation’s effort in space? Are the traditional rationales in favor of human spaceflight sufficient to win support for the effort into the future? While Americans seemingly want the fruits of human spaceflight, too many are unwilling to invest in it. The rationales, as real as they might actually be, seem less compelling today than in the past. What compelling rationales offer a way forward for astronauts to push back the frontiers of the cosmos? I hope we will resolve the challenge of compelling rationales for human spaceflight into the future.


Roger D. Launius is a senior curator at the Smithsonian Institution’s National Air and Space Museum in Washington.

Roger D. Launius is a senior curator in the Division of Space History at the Smithsonian Institution's National Air and Space Museum in Washington