The recent release of “The Martian” movie has drawn public attention to the challenges, risks and rewards of sending humans to the surface of the red planet. While in a few instances the movie distorts reality for the sake of a compelling story, those in the non-Hollywood world planning for actual human journeys to Mars do not have that luxury; they must find a path to Mars that is technically feasible, affordable and sustainable over several decades.

Both of us have been subject to countless presentations of potential Mars architectures and attended dozens, if not hundreds, of meetings about the future of human spaceflight. Yet until recently the goal of humans at Mars has felt as distant as ever.

But things are changing. As NASA Administrator Charlie Bolden is fond of saying, “We are closer today to sending people to Mars than even before.” With the current development of the Space Launch System and Orion, NASA will have key pieces of the hardware needed to send humans into deep space. A new world of commercial space services has demonstrated the potential to lower the cost of accessing low Earth orbit (and perhaps beyond), freeing up NASA to focus its energies on grander goals. NASA’s Evolvable Mars campaign, while lacking needed definition, represents an important first step in aligning the efforts of its various field centers, personnel and contractor base to the Mars goal. In addition, a recent presentation by the NASA chief medical officer indicates that a major previous unknown — the effect of space radiation — has now become more of an issue of informed consent rather than a roadblock to exploration.

NASA’s constrained budget remains a limiting factor. The 2014 National Academies’ Pathways to Exploration report was clear on this: No existing NASA plan for human spaceflight would be possible under a flat budget scenario. Even a budget that grew with inflation would not succeed in getting humans to Mars before the mid-2040s, given the Mars exploration scenario on which NASA was basing its planning.

To explore how NASA could structure a program of human exploration of Mars that is sustainable, affordable and executable, the Planetary Society, the world’s largest citizen-based space advocacy organization, convened a workshop in Washington earlier this year. The authors, both members of the society’s board of directors, co-chaired the gathering, which brought together key leaders from NASA’s science, technology and human spaceflight directorates, individuals from major industry partners, leading scientists, policymakers and congressional staff. We adopted as an organizing principle for the agenda the goal of addressing the commonly cited technical, budgetary, policy and scientific obstacles to exploring Mars with humans. The report of the workshop, titled “Humans Orbiting Mars: A Critical Step Toward the Red Planet,” was released Sept. 29 and is available online.

A focal point of workshop discussions (and of the workshop report) was a minimal Mars exploration architecture developed by a study group at the Jet Propulsion Laboratory as input to the current NASA planning process. The study team proposed a series of missions leading to a long-term human presence on the surface of Mars, including hardware demonstration missions in cislunar space throughout the 2020s, a Mars orbit/Phobos mission in 2033, a human landing on the moon in 2035 to validate landing hardware, and a short-stay surface mission on Mars by 2039. To the maximum extent practicable, the plan utilizes programs already in development or under study at NASA (like the SLS, Orion and Solar Electric Propulsion tugs), limiting new hardware development and thus minimizing a common source of budget overruns and schedule delays.

The JPL study team asked the Aerospace Corp. to subject its plan to the same cost analysis approach Aerospace had applied to the Mars exploration concepts in the 2014 Pathways to Exploration report. Aerospace found that the JPL architecture could plausibly be implemented within a human spaceflight budget that grew only with inflation, provided only that NASA withdraws from its lead role in funding operation of the International Space Station by the mid-to-late-2020s. The half-trillion-dollar price tag for getting to Mars that was a product of the 1989 Space Exploration Initiative is clearly no longer a relevant benchmark.

Traveling only to Mars orbit during the first human foray to the Martian system has space program precedents. As discussed at the workshop, Apollos 8 and 10 orbited the moon before Apollo 11 landed. Mariner missions orbited Mars before the Viking spacecraft landed. An initial orbit-only mission would focus on the critical systems and techniques needed to sustain humans during their voyage to the vicinity of Mars and back. It would defer dealing with the costs and risks associated with developing and demonstrating the capability to land on the Martian surface.

The workshop also explored the significant scientific potential of sending humans to Mars orbit and to explore Phobos, and how an orbit-first mission could easily fit within a grand narrative of Mars exploration by which NASA could engage the public.

While NASA would have the lead role in implementing this architecture, it would need partners in the enterprise. International partnerships are widely acknowledged as a necessity for any major undertaking in space. Other nations can contribute technical expertise and monetary support, and collaboration in space contributes to the strengthening of international relationships on Earth. However, without a clear strategy for reaching Mars, defining such partnerships will be difficult. In a similar vein, the private sector would benefit from a clear government strategy to assist in defining its potential role in the human exploration of Mars.

The “Humans Orbiting Mars” workshop was intended to provide a starting point for engaging a broad range of relevant stakeholders — scientists, technologists other groups interested in exploring Mars, major industry invested in existing programs, new private-sector space firms, international partners, political leaders, wide swaths of the public, and NASA itself — in a discussion of how to approach a sustainable program of human Mars exploration. Of course, the architecture laid out by the JPL study team is not the only path forward, nor was it meant to be — it is an initial “proof of concept” of one way to get to Mars. At this early stage it is impossible for any plan to anticipate all the future technological, political and engineering advances, disruptions and challenges yet to come. The JPL study team has, however, suggested that an orbit-first strategy is a compelling solution to problems in cost, sustainability and coalition-building.

Even a human spaceflight budget that grows with inflation will be difficult to maintain. Building of a broad coalition to help sustain the endeavor over time will be crucial. There is widespread agreement that sending humans to Mars should be the “horizon goal” for the U.S. space exploration program. Articulating a specific strategy for achieving that goal will provide the focus around which this coalition of stakeholders in government, industry, science, Congress and the public can emerge. The movie “The Martian” has the luxury of assuming this coalition exists at the time the events depicted unfold. We do not.

One conclusion of the workshop was that a “Kennedy moment” — when a national leader commits the United States to “bear the burden and pay the price” of a major space undertaking — is very unlikely to reoccur. So it will be such a stable coalition of supporters that will provide the foundation for what will once again be a venture that, as John Kennedy said over 50 years ago with respect to Apollo, will “organize the best of our energies and skills.” The time to form that coalition is upon us.

Scott Hubbard is a professor in the Department of Aeronautics and Astronautics at Stanford University and former director of NASA’s Ames Research Center. As “Mars czar” he redesigned the NASA robotic Mars exploration program after two failures in 1999. John M. Logsdon is founder of the Space Policy Institute at George Washington University’s Elliott School of International Affairs, where he is professor emeritus.