American Scientist

In January 2004, President Bush announced his "New Vision for Space Exploration" in a White House document titled "A Renewed Spirit of Discovery." It was, and still is, widely welcomed in the aerospace community as a response to the loss of the space shuttle Columbia and the resulting need to define a purpose for human space flight in a way that justifies the cost and risk.

The vision was remarkable because it included strong support for space science and robotic space exploration—for example, returning samples from Mars and searching for Earthlike planets beyond our solar system. But its primary focus was to set a new course for the human exploration of space, first with missions to the Moon and then to Mars. Even "beyond" was contemplated.

The first step, though, was simply to replace the space shuttle. The aging and tragically reduced shuttle fleet would, for reasons of safety, require either retirement or complete (and expensive) refurbishment. The latter option would block any move to send astronauts beyond low-Earth orbit. Thus the president committed to retiring the shuttle and ending its expensive operations, which would free resources to build a new rocket and get started on implementing the vision. The mantra was "go-as-you-pay": Future activities would be financed using funds that became available from the cessation of the shuttle program and from an anticipated modest growth in the NASA budget.

That was the theory. Practice has turned out a little differently. Despite the lip service given to the topic, including resolutions in Congress, promised increases in funding for the new initiative were neither proposed by the administration nor offered by legislators. Funds will presumably become available after the shuttle is retired in 2010, but in the meantime money is tight.

Not only does work on the vision have to be funded, but past-due bills arising from the Columbia accident had to be paid. No money was allocated for such obligations in the administration's first budget after it presented the vision. Rather, NASA was told to cut back on planned robotic exploration and space science and use those funds to implement a more narrowly focused version of the vision, one that weakened the goal of preparing for missions to Mars. Instead, the Moon was made the vision's destination, and the resulting Constellation program was described as "Apollo on steroids."

The redirection of planned science funding opened a rift between the science community and the human space-flight community. That effect was ironic, because "A Renewed Spirit of Discovery" had specified an integrated set of missions, robotic and human, with both science and exploration goals.

Breaking Ranks

This split between the science and human space-flight communities has undermined political support for the vision and provided a weapon to those opposed to funding human space flight at all. The goal of returning people to the Moon has failed to spark much public interest, and the administration's rationale "to bring the Moon into our economic sphere" has inspired few.

Furthermore, with reduced funding for both science and exploration, questions have emerged about how NASA has decided to implement the vision—about building a new Ares launch vehicle instead of using the existing Atlas and Delta rockets, about the cancellation of work on a Mars sample-return mission and about the approach being taken to international cooperation in space, to name a few of the issues. But the biggest question of all was how to sustain the vision and the commitment to human space flight beyond Earth orbit when a new administration takes office in January 2009.

Almost certainly, high among the coming administration's priorities will be a renewed emphasis on using satellites to help Earth scientists observe and understand various forms of global change. As important as this work is, the Earth-science program has little need for (or influence on) human space flight.

For all of these reasons, especially that of looking ahead to a new administration, the Planetary Society and the Department of Aeronautics and Astronautics at Stanford University decided to organize a two-day workshop last February to examine the vision and the balance between science and exploration in the nation's future space programs. We assembled some 50 experts with various backgrounds and experience in space exploration to comment on U.S. space policy. In the group were eight former astronauts. Bringing them along with scientists, engineers, policy analysts and industry executives into a single conversation was our goal.

The topics discussed included scientific investigations of extraterrestrial bodies, Earth science and climate change, the planned lunar missions, eventually sending humans to Mars, alternative destinations for astronauts to explore, using people or robots in outer space, vehicles for accessing low-Earth orbit and beyond, emerging entrepreneurial activity, and international collaboration.

One of the great surprises to the organizers of the workshop (the two of us, former astronaut, now University of Virginia professor, Kathy Thornton and former NASA Associate Administrator Wesley T. Huntress, Jr.) was that this diverse group was able to reach consensus on several important points.

We found general agreement with the notion that human space exploration is undertaken to serve national and international interests and that it provides important opportunities to advance science—but that science is not the primary motivation. Participants were also mostly of the opinion that human exploration requires enhanced international collaboration and that the undertaking offers the United States an opportunity for global leadership. The participants agreed that the purpose of sustained human presence in space is to go to Mars and beyond and that the significance of the Moon and other intermediate destinations is to serve as stepping-stones along that path.

The people we brought together at the workshop also noted that NASA has not received the budget increases needed to support the mandated human exploration program as well as other essential parts of the agency's portfolio—including space science, aeronautics, technology development and especially Earth observations, which are vital given the urgent concerns about global climate change.

Mars or Bust

Finding out that advocates of the nation's space program consider it to be underfunded was not much of a surprise. But this was nevertheless a key conclusion to come from the workshop, and to the general public this appraisal may not have been obvious. The redirection of science funds to pay old bills from the shuttle program and for emergency allocations required for NASA facilities affected by hurricanes has been undermining the vision.

Statements at the workshop about the importance of going to Mars and of international cooperation as a rationale for human space exploration are also very important. We believe that moves in these directions would substantially increase and sustain popular support for the space program. We also believe they would enable the next administration to justify spending money on space exploration and to ensure that it will truly be carried out for the benefit of all humankind.

Why would such redirection help? Mars is a place with an atmosphere and water, where life could have formed and where ultimately it will be determined whether we become a multi-planet species. It is an obvious target for exploration in the popular imagination and has already been visited by robots, generating much public enthusiasm. For scientists, inquiry into the origin and evolution of life compels the further exploration of Mars. The Moon is a stepping-stone for nations that are just now becoming space faring and for the United States and Russia, which have to renew their capabilities to explore beyond Earth orbit. It can also serve as a good waypoint for an emerging cadre of space entrepreneurs. But as a human destination, this dead world is a dead end.

There might be other stepping-stones, too. In a 1994 study, the International Academy of Astronautics emphasized the value of the stable "L" (Lagrangian) points in the Earth-Sun system, the near-Earth asteroids and the Martian moon Phobos. Missions to these places offer interesting and potentially valuable rewards in their own right, in addition to advancing the capability for sending astronauts on long interplanetary voyages. But their greatest value could be to supply what is missing in the current human space-exploration plan—publicly engaging milestones on the road to Mars.

The workshop attendees emphasized that human space exploration serves overarching national and international interests. Some believe this means positioning ourselves for a new space race with China, but a greater triumph would come from international cooperation. The International Space Station provides a basis for a future in which many nations work together to reach the Moon and Mars. Such collaboration would be the most direct way to attain greater financial and technical resources, as well as domestic political support, for the grand adventure of human exploration of other worlds.

We believe that thoughtful discussions, such as the ones that went on during our workshop, can make the space program more relevant and more engaging to the public. And only with popular backing can we sustain a healthy space program, not just over the next presidential administration, but perhaps over the next century.