The U.S. president’s vision of a settlement on the Moon and a human voyage to Mars revives a long-held hope of resuming our exploration of our universe. NASA has responded vigorously in program planning and initial development of launch and crew vehicles, but has not yet been given either the authorization or the budget for the overall program.

Such a Moon/Mars effort will be a huge undertaking. The full cost of the Apollo program, our most ambitious space venture to date, exceeded $125 billion in today’s dollars. A Moon settlement will require far more support and supply missions. Its considerably greater cost will require long-term commitment, dependable, sustained appropriations, and strong, patient public support based on appreciation of the expenditures and the benefits. A successful Moon mission may enhance the prospects for a more challenging Mars voyage.

To focus effectively on exploration with no significant budget increases, NASA has been forced to make deep cuts in its science, space applications, Earth observations, astronomy and aeronautics research. The cuts not only impair ongoing work, but also in some instances threaten irreparable damage to long-term capability. These are areas in which private-sector investment is severely limited because of the high risk, high cost and little or no likelihood of proprietary commercial reward. Government support of aeronautics and space research is essential, and over the years has greatly strengthened the nation’s position in a world increasingly dependent on scientific and technological progress. It has made possible advances in civil and military aviation, astronomy, communication, computational capabilities, Earth sciences, and navigation that would have been inconceivable less than half a century ago.

An important corollary has been the growth of an aerospace industry that supports more than a half-million high-quality private-sector jobs and provides a major positive component of the U.S. balance of trade. Aerospace also has inspired a generation of science and engineering graduate students.

If we are serious about space exploration, we must face up to the cost and act responsibly to provide and sustain the needed support. And we must understand that it requires new additional investment and cannot be funded simply by curtailing effort in other areas of NASA responsibility.

Continuing growth in domestic and international air transportation increases the importance of research toward greater safety, cost reduction, fuel conservation, system capacity and environmental protection. Space applications offer opportunities far beyond the already proven benefits in communication, navigation and weather forecasting. Greater emphasis on Earth observations and on solar-terrestrial science is essential to the long-term survival of human civilization by providing understanding of the threats and means to mitigate them. As repeatedly stated by respected scientific, academic and industry advisory bodies, these research programs address critical national needs and, along with space exploration, fulfill the mandate of NASA’s authorizing legislation.

Disruptions in these important NASA efforts would be unfortunate enough. But destroying them without reasonable assurance of sustained exploration progress would be inexcusable. And to date, no such assurance exists. The exploration vision remains underfunded while the research is being seriously weakened.

If the president and Congress agree on the goals and timing of lunar and planetary exploration, a clear national policy to that effect, based on realistic appreciation of total cost and thorough planning, should be established. Out-year budgets will of course be driven by evolving circumstances but, if the policy is to be at all meaningful, immediate funding should be significantly increased so that NASA can continue to prepare for the new mission without undue damage to its science and aeronautics research programs.

With such policy guidance and long-term commitment, we can look forward confidently to one of the greatest accomplishments in human history. Without them we risk having wasted large amounts of money on an aborted effort and having unjustifiably decimated vital aeronautics and space research.

Richard H.Truly, Robert A. Frosch and James M. Beggs are former NASA administrators who authored this Commentary on behalf of the NASA Alumni League, a nonprofit organization of former NASA NACA, and Jet Propulsion Laboratory employees and those assigned to NASA from other agencies for a year or more.