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

Implications for U.S. Human Spaceflight Policy

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

How does specifying primary and secondary objectives for human spaceflight (and exploring the mix of objectives in other nations’ human spaceflight programs) inform the policy decisions currently facing the United States? If we accept this framework of objectives, or even one similar to it, what are the policy implications? Clearly, no conceptual framework will deterministically resolve all current policy dilemmas. But a framework should shed light on how to imagine ways forward. Ultimately, these questions lead us to ask: in what type of human spaceflight program should the United States invest?

Why are such questions necessary? History shows that inconsistent objectives lead to an inconsistent space program and that coherent objectives yield a coherent space program. By their nature as large, complex technological systems, human spaceflight programs integrate numerous facets, from national policy to organizational cultures, technical decisions, and even operational plans. Without clear conceptions about the objectives of such programs and their relative priorities, these facets will not align into a coherent whole. Kennedy’s 1961 objectives for the Apollo program, clearly based on national pride and international prestige, on the desire to beat the Soviet Union to the Moon “before this decade is out,” had implications right down to the “nuts and bolts”—the most basic technical choices made by NASA engineers. Though the Apollo program may have occurred in a unique political environment, even in the current resource-constrained environment the United States must clearly define a set of primary objectives that will shape the architecture and technical design of new space systems. When technical choices are made in a policy vacuum, they can constrain capabilities and future policies in undesirable ways.

We acknowledge that policy choices are not based on primary objectives alone. Politics, bureaucratic give-and-take, international relations, and a host of other factors influence any decision and program. For instance, we characterize objectives such as job creation and retention as secondary—they are not worth the risk to human life and arguably not worth the opportunity cost— but they nonetheless remain central for members of Congress. Similarly, primary objectives differ among nations, so any decisions either to collaborate with or compete against other nations must take into account their disparate goals and must fit into the overall framework of U.S. foreign policy. Nonetheless, a workable conceptual core should be able to take a great number of these factors into account.

The remainder of this paper, then, examines some of the current policy issues in light of primary and secondary objectives and their global parallels. We look at several decisions:

  • When should the United States retire the space shuttle?
  • How should the nation utilize the International Space Station?
  • How should future plans balance the Moon, Mars, and other possible destinations?
  • What should be the balance between human and remote/robotic missions?
  • How should the United States demonstrate global leadership in human spaceflight?

The first decision, retirement of the space shuttle, is of immediate interest. President Obama’s FY2010 budget suggests that the 2010 retirement will proceed as scheduled, but we still see value in examining the decision as an exercise. The later decisions, though of less immediacy than the shuttle retirement, will face the nation in the next four to eight years.

Our framework does not provide simple, direct answers to any of these questions. In fact, for some cases, it highlights contradictions that may be irresolvable with current programs. For other cases, however, it does show logical directions that would generate a consistent and coherent program. For all, it provides a framing of the issues and a set of terms for discussion.

Retirement of the Space Shuttle

As its first critical space decision, the Obama administration will decide whether to retire the space shuttle. The shuttle was originally developed in part to support a space station, and the ISS, now nearing completion, was designed to be serviced by regular shuttle visits. Continuing to fly the shuttle while developing the Constellation vehicles, however, will cost billions of dollars above NASA’s current budget. Delaying shuttle retirement to support the ISS might have its advantages, but a delay does not support the United States’ primary objectives for human spaceflight.

The space shuttle, seen as both the symbol of American technical excellence and as a “policy failure,” has passed its design life.178 Despite the age of the orbiters, the nation made no strong attempt to replace them during their first thirty years. The CAIB report described this situation as “a failure of national leadership.179 Analyst John Logsdon considers this failure in depth, stating that the United States has been:

willing, over the past 35 years, to continue a human spaceflight program, but only at a level of funding that has forced it to constantly operate on the edge of viability. . . . [T]he assertion [by the CAIB] that the lack of a Shuttle replacement is a “failure of national leadership” is the logical result of the half-hearted U.S. commitment to human spaceflight.180

The national leadership required to make a decision on replacing the shuttle finally emerged after the Columbia accident. In its discussion of the future of the space program, the CAIB recommended that the orbiters be recertified by 2010 for “continued use . . . to 2020 and possibly beyond.”181 Because NASA intended at the time of the accident to fly the orbiters for another decade at least, members of the CAIB describe their goal as stimulating NASA to improve the safety organization around the shuttle.

In light of the CAIB report, however, and in order to free funds to develop Constellation vehicles, the Bush administration decided to retire the space shuttle rather than perform a formal recertification. Because only the shuttle has the capacity to carry much ISS hardware into orbit, NASA has almost exclusively dedicated the remaining shuttle missions to completing station assembly. Meanwhile, since 2005 the shuttle program has been shutting down capabilities including workforce, facilities, and equipment. Based on a 2010 retirement date, the program no longer needs items such as star trackers or tires and is closing contracts and ceasing hardware production with the 1,500 companies that supply shuttle components.182

Reasons to postpone retirement center on the need to support the ISS. Flying the space shuttle past 2010 gives NASA greater flexibility for ISS maintenance, supports the delivery and return of research materials, and maintains the operational workforce at NASA. A delay in retirement could shorten the gap between the shuttle and the first flight of the Orion spacecraft, maintaining independent U.S. crew access to the station.

Many larger components of the ISS, including orbital replacement units (ORUs) such as the gyroscopes that hold the station’s attitude, were designed for transport aboard the shuttle and cannot be carried in any other cargo vehicle. The shuttle can carry more mass and has greater volume than any existing or planned alternative. For unpressurized cargo such as the ORUs, the Japanese HTV has 565 cubic feet of volume compared to the approximately 10,500 cubic feet of the shuttle’s payload bay (neither the Russian Progress nor the European ATV can carry unpressurized cargo).183 For pressurized cargo, such as experiment racks or supplies, the Progress can carry 4,000 pounds of mass, the ATV can carry 12,125 pounds, and the shuttle can carry a Multi-Purpose Logistics Module with a cargo capacity of nearly 21,000 pounds.184

NASA’s strategy for maintaining the ISS was originally based on availability of the shuttle to provide spare parts “on demand.” After the Bush vision was announced, however, NASA changed its maintenance strategy from providing spare parts when necessary to prepositioning ORUs that might be needed over the next decade. The remaining flights (listed in Table 1) will deliver as many components as possible to the ISS before retirement. However, in the event the ISS uses ORUs at a faster rate than anticipated, the shuttle’s cargo capability would be valuable for delivering necessary hardware to the station.

Table 1: Remaining Space Shuttle Missions, as of September 2009

Mission Orbiter Projected
Launch Dates
STS-129 Atlantis Nov. 12, 2009 EXPRESS Logistics Carrier 1 and
EXPRESS Logistics Carrier 2
STS-130 Endeavour Feb. 4, 2010 Tranquility Node 3 and the Cupola
STS-131 Discovery March 18, 2010 Multi-Purpose Logistics Module and a Lightweight
Multi-Purpose Experiment Support Structure Carrier
STS-132 Atlantis May 14, 2010 Integrated Cargo Carrier and the Russian Mini
Research Module 1
STS-133 Endeavour July 29, 2010 EXPRESS Logistics Carrier 4 and a
Multi-Purpose Logistics Module
STS-134 Discovery Sept. 16, 2010 EXPRESS Logistics Carrier 3 and the
Alpha Magnetic Spectrometer

NASA may switch the order of STS-133 and STS-134 in the manifest. Source: NASA, “Consolidated Launch Manifest,” n.d.,

In addition to launching hardware to orbit, the shuttle also can return cargo, or “downmass,” to Earth. Without this downmass capability, astronauts will dispose of unwanted equipment in space, as opposed to returning it for refurbishment and reuse. Many life-science experiments, however, are depending on cargo return. Biological research and animal experiments, for example, generate samples that need to be carried back to Earth in freezers. A NASA advisory council anticipated a downmass requirement of nearly 10,000 kilograms (22,000 pounds) of pressurized cargo from 2006 to 2010.185 Whereas the shuttle is capable of returning thousands of pounds of cargo, the Soyuz is able to return only tens of pounds. Other cargo vehicles such as the Progress or ATV lack the ability to return to Earth, and are destroyed upon reentry into the atmosphere. Maintaining the shuttle would support the down-mass requirements of much of the life science research originally planned for the ISS.

Besides its continued use as a cargo vehicle, the shuttle would also maintain independent U.S. crew access to the ISS. Former NASA administrator Mike Griffin describes as “unseemly” a situation in which the United States must rely on the Russian Soyuz for astronaut transport.186 From a budgetary perspective, NASA would pay orders of magnitude less money for the Russians to transport astronauts ($51 million per astronaut) than it would to maintain the shuttle. However, an underlying concern of this dependence is that heightened tensions between the United States and Russia could result in Russia denying U.S. access to the station.187 Given Russian motivations in space, this scenario is debatable, and in any case, maintaining the shuttle does not lessen the reliance on the Russians: because the orbiters can remain at the station for only two weeks, a Soyuz vehicle (or two Soyuz vehicles for a six-person crew) must always remain docked and available for crew rescue. Postponing the shuttle retirement reduces, but does not eliminate, reliance on the Russians for crew transport.

Lastly, beyond issues of ISS support, maintaining the shuttle will keep in place the workforce supporting the program and will maintain their operational proficiency. Although NASA plans to retain much of the shuttle workforce by transferring people to Constellation, the high unemployment that may result from ending the shuttle program remains a concern, particularly at NASA’s Kennedy Space Center in Florida. For this reason, the administration could choose to maintain the shuttle as a jobs program.

Given these arguments in favor of postponing the shuttle’s retirement— bringing necessary cargo to the ISS, returning downmass to Earth, maintaining U.S. crew access, and keeping the workforce employed—what guidance can primary objectives provide to policy-makers? If policy-makers accept that the primary objectives of the U.S. human spaceflight program are based on some combination of exploration, national pride, and international prestige, what are the implications for the space shuttle?

Primary objectives suggest that the shuttle still be retired. The most pressing reasons remain its high cost, the opportunity cost of not moving forward with the exploration program, and risks of another accident.

Consider first the role of the space shuttle as a cargo delivery and return vehicle. Since the Challenger accident, the nation has accepted that human lives should not be risked for cargo delivery (or return). The first criterion for primary objectives—that human presence is necessary for the tasks—is not met for the role of the shuttle as purely a cargo vehicle.

The difficulty in the current circumstances is that the ISS was designed to be supported by the shuttle, which requires a human crew. NASA, however, has been planning for the shuttle retirement since the Bush vision was announced, and other vehicles (European ATV, Japanese HTV) are becoming available to make up for the lost cargo capacity. NASA initiated the Commercial Orbital Transportation Services (COTS) program to address the up- and downmass shortfalls. A cargo return capability for the COTS spacecraft (the COTS “C” option) is warranted because ISS research is a beneficial secondary objective of human spaceflight even if it does not justify continued space shuttle flights.188

Consider next the objective of maintaining the operational space shuttle workforce. Despite the attention that workforce issues have with members of Congress, this is a secondary objective of human spaceflight and is not worth the risk of human life.

The final objective in postponing the shuttle retirement, maintaining independent U.S. crew access to the station, poses more complex questions. The decision to rely on Russia for U.S. astronaut transportation clearly involves aspects of national pride and international prestige, both primary objectives of spaceflight. If policy-makers believe either that American pride would not accept astronauts flying on Russian Soyuz or that a deteriorating international relationship between the United States and Russia would limit access to the station, then these primary objectives could justify maintaining the shuttle.

A broader examination of the U.S. objectives for human spaceflight does not support this interpretation, however. Although national pride is a primary objective, it is unlikely to support extending obsolete, aging, and risky hardware. And an examination of the Russian space industry suggests that a scenario whereby Russia prevents astronauts from flying on the Soyuz is not likely.

Is the perceived loss of international prestige during the “gap” great enough to be worth the money, the opportunity cost, and the risk to human life of continuing to fly the shuttle? If the highest priority objective of U.S. human spaceflight is exploration, however defined, these costs and risks outweigh the concerns of independent U.S. access.

For instance, no matter the number of actual launches, NASA requires funding of billions of dollars per year to maintain the shuttle. A short-term delay in retirement to 2012 is estimated to cost a total of $5 billion; a longer delay to 2015 could cost up to $11 billion.189 These costs are huge compared to the $51 million per astronaut to fly on the Soyuz; they must be borne either by a corresponding increase in the NASA budget or by a shift in funds away from the exploration program. Assuming that the economic conditions preclude an increase in NASA’s top-line budget by these amounts, the opportunity cost of maintaining the shuttle would be a reduction in the Constellation budget, which would delay the first launch of Orion and push back missions beyond low Earth orbit. Maintaining shuttle operations will shift the gap, not close it. If exploration remains a primary objective of spaceflight, continuing to fly the shuttle for international prestige would inflict a high cost on future U.S. efforts in space.

Any discussion of the shuttle must also include the increased risks of an accident that accompany additional flights. NASA estimates that even through the current 2010 retirement date the chance of losing another orbiter is 1 in 77. Another disaster would cost astronauts’ lives and also endanger the future of the space program. Keeping the shuttle for ISS support when NASA has other options for accessing the station does not satisfy the criterion of human spaceflight being worth the risk to human life.

For these reasons, extending space shuttle operations does not satisfy the primary objectives of spaceflight. Although the ISS would benefit from the shuttle’s capacity for cargo delivery, the nation would pay a large opportunity cost for this benefit. Further, the administration must decide whether a basic level of U.S. crew transport independence, wherein the United States must still rely on Soyuz for emergency crew return, is worth the risk to human life from further shuttle missions. We conclude that the administration should allow NASA to focus on future success in developing a new generation of human spaceflight technology. This focus promises to renew U.S. pride in the space program and support the United States’ primary objective of global leadership in human space exploration.

  • Continuing to fly the shuttle past 2010 does not advance U.S. primary objectives for human spaceflight. Although some potential benefits might be realized by extending the program, they support secondary objectives that do not justify the risk to human life.
  • The current shuttle manifest should be flown to its scheduled conclusion, even if that schedule slips somewhat past 2010, and then the shuttle should be retired.
  • NASA should continue to support commercial, European, and Japanese development of crew and cargo alternatives, particularly for cargo return, during and after the gap.

Utilization of the International Space Station

The decision to build a U.S. space station was made in 1984, and the resulting station—the ISS—has taken NASA and its sixteen international partners an estimated $100 billion and more than twenty-five years of development to complete. Yet even as the station assembly nears its end, questions remain regarding to what purpose and for how long the facility will be used. The opportunity cost of this assembly is huge. One wonders what else could have been accomplished with the budget and time dedicated to its assembly (perhaps a much smaller facility or a complex spacecraft ready to depart for Mars).

Envisioning the future of this investment entails answering two basic questions. First, how can the United States best utilize this permanently crewed laboratory facility? Second, how long should the United States keep the ISS? The Bush vision implied that the United States would no longer support the station after 2016.

The laboratory space aboard the ISS offers research and development opportunities found nowhere else on or above Earth. The station’s key attribute is the microgravity environment (“weightlessness”) combined with the presence of human crews. Life scientists require human presence to understand the effects of long-duration spaceflight on human health, and such research also provides a unique perspective on medical problems on Earth. Engineers, too, find the microgravity environment of the ISS a valuable laboratory for technology development that benefits both exploration and unmanned space missions.190 Because the crew is present to stop and restart experiments, investigators can test immature technologies and push the technological envelope with the knowledge that in the case of any failure an astronaut can press the “reset” button for another try.

Significant research aboard the ISS, however, awaits the completion of assembly in 2010. Until the recent increase in crew size, the three-person crew was able to devote only 10 percent of its time to research because of the maintenance needs of the growing station. NASA plans to use the period leading up to full mission operations to prepare experiments and research teams, but significant challenges exist for full utilization.191 These challenges include the lack of consistent research goals, the lack of funding for the research community to use the station, and the limited time remaining to prepare experiments.

After the Columbia accident, the Bush vision focused on using the ISS almost exclusively to test technologies and develop medical countermeasures for NASA’s new exploration efforts.192 Despite this emphasis, in 2006 the National Research Council questioned whether NASA’s research plan was appropriately aligned with its exploration needs. The NRC described NASA efforts to align research with exploration needs as “nascent,” even though “the ISS may well represent the only timely opportunity to conduct the R&D that is necessary to solve exploration problems and reduce crew and mission risks prior to a Mars mission.”193 Meanwhile, in 2005, Congress named the ISS a “National Laboratory” in order to expand its usefulness beyond the exploration program, and to promote research sponsored by other federal agencies and by nongovernmental players.194 The ultimate balance of exploration- and nonexploration-related research within the ISS research portfolio remains unclear.

Funding for ISS research has also taken severe cuts. The research community preparing to use the station was devastated after 2005, when NASA’s research-focused Office of Biological and Physical Research merged with its new Exploration Systems Mission Directorate, and its $1 billion budget was effectively zeroed. The NRC makes the point that “once lost, neither the necessary research infrastructure nor the necessary communities of scientific investigators can survive or be easily replaced.”195 A 2008 NRC study of NASA’s Exploration Technology Development Program concluded that the reduction in funding “will have long-term consequences and result in compromised long-term decisions. Extensibility to longer lunar missions and to human exploration of Mars is at risk in the current research portfolio.”196

The third great challenge is the amount of time remaining before full ISS utilization begins. On average it takes three to five years to design an experiment, build the hardware, pass necessary NASA safety review boards, and prepare for launch. For biomedical research into long-duration spaceflight, where a large number of subjects are necessary to produce useful data, all major life-science investigations should have been selected by 2006 in order to finish by 2016. In fact, most were canceled in 2005. NASA highlights some “pathfinder” experiments that were prepared in a year’s time, but in order to get the most use out of the ISS this research community must be recreated and project development started as soon as possible.197

In addition to grappling with these challenges in utilizing the station, policy-makers must also decide when to retire the ISS. The 2016 retirement date suggested in the Bush vision, only six years after NASA completes assembly, was arbitrarily chosen based on the fifteen-year design life of the U.S. laboratory module (launched in 2001). Node 1, launched in 1998 before the laboratory module, is already nearing the end of its design life and must be recertified by 2013. NASA projects the cost of operating the ISS at $2.1 to $2.4 billion per year. These costs could convince policy-makers to cut short any utilization in order to free resources for Constellation and gain operational experience on the Moon.198 In this case, NASA has only four years to demonstrate the “benefit and cost prospects for extended ISS operations” before a decision on extending its life is required.199

Given these issues, the ISS provides a complex case for the objectives of human spaceflight. Based on this framework, building a station the size and cost of the ISS may not have been justified by the primary objectives of exploration, national pride, or by international prestige. Although images of men and women who call the station home for six-month visits represent an expansion of the human experience, does that justify the opportunity costs? Now, however, the question is immaterial; the station exists. How do primary and secondary objectives help frame the future of the ISS?

Although scientific and research efforts involving human spaceflight are, in our framework, secondary objectives, they are central to maximizing the utility of the station. As long as primary objectives justify the station’s continued existence, these secondary objectives may warrant a greater level of support than NASA is currently receiving. Life-science research is necessary to support primary exploration objectives to the Moon and beyond. Indeed, the major contribution of the ISS to exploration is in learning how to support human beings in space for periods of time exceeding those of a human Mars mission while gaining experience with resupply and logistics needs. The ISS experience reduces the uncertainty of future exploration missions, directly supporting primary objectives. Other secondary objectives, such as technology development, can greatly benefit from human presence but require research support, preparation, and launch opportunities to achieve a return on the investment in the ISS. The station can contribute to space research, satisfying secondary objectives of spaceflight. But the opportunity costs of the ISS will surely rise if, after all of the sunk costs are spent, inadequate resources are provided to make use of the facility.

These secondary objectives, however, do not justify the risk to human life. In order to justify continued human presence on the station, and to address the question of how long to keep the station, policy-makers should consider the primary objectives of the project.

The primary objective of the ISS has always been international prestige rather than exploration. From the start it was an international partnership among the Western allies. With the inclusion of the former Soviet Union, the ISS became an example of post–Cold War cooperation. In the Bush vision, completing the ISS was justified by the need to maintain the partners’ trust that the United States would not back out of its space agreements.

Congress has called upon NASA to ensure that the ISS “remains a viable and productive facility” through 2020, and international prestige provides a strong objective to maintain the station beyond 2016.200 The Japanese and European modules were launched only in 2008 and will not have reached the end of their ten-year design life until 2018. After the expense of assembling the ISS, the international partners would likely see its abandonment after only six years of full operation as an abrogation of U.S. responsibilities with implications for future cooperation.

The ISS also clearly represents an example of, and possibilities for, international collaboration. Utilizing the station for the design life of all its modules would support American efforts to build a similar partnership for the exploration program. The primary objective of international prestige would appeal to an administration focused on increasing America’s global leadership. Further, by involving Russia, the ISS “arguably has done more to further understanding and cooperation between the two nations [the United States and Russia] than many comparable programs.”<sup> 201 Despite the challenges of coordinating with all station partners, the ISS partnership can serve as a blueprint for future cooperation.

The framework supports utilization of the ISS to meet both primary and secondary objectives. The administration and Congress should provide direction regarding the balance of research efforts, as well as funding to support the research community, to ensure that the opportunity provided by the ISS is not wasted.

  • Congress and the new administration should reevaluate the research balance between immediate goals of exploration systems, basic science, and nonexploration-related technology development. Research communities that will use the ISS should be reconstituted in time for the post-2010 utilization period. A clear structure for selecting, supporting, and launching experiments should be established and articulated.
  • The United States should work with its partners to develop a broad, funded plan to reduce operating costs and utilize the ISS through 2020 for research in the physical and life sciences, for development of technologies to support exploration for both Moon missions and long-duration Mars flights, and as a laboratory for space technology development.

To the Moon and Mars

The Bush vision directed NASA to land astronauts on the Moon by 2020 in preparation for eventual Mars missions, but it did not specify the size of the lunar program or how long the United States would remain on the Moon. NASA’s current plans remain ambiguous about the relationship between a Moon and a Mars mission, and this ambiguity is generating heated debate about the appropriate balance between the two. (Other potential missions to near-Earth asteroids or Lagrangian points are also being debated.) Some argue that extended presence on the Moon is a necessary precursor to human-crewed Mars flights.202 A lunar laboratory, for example, would help scientists understand the effects of lunar gravity, dust, and radiation on human health, with the goal of preparing for next steps to Mars. Others worry that a lunar outpost could evolve into an expensive facility that drains resources from further exploration goals.203 Given this background, what are the primary and secondary objectives of a Moon/Mars program?

Perhaps nowhere is the articulation of primary objectives more critical than with the exploration program. The program is affected by short- and medium-term decisions, such as the shuttle retirement and the development of the Ares V heavy-lift vehicle, which should be based on these objectives. Moreover, the long-term vision of the exploration program, including the exit conditions for the lunar portion, as well as the likely funding profile, impact immediate decisions. This is particularly true if, as the Bush vision contends, the Constellation program’s goal is to progress from the Moon to human missions to Mars. Consider the following three examples.

First, the focus of ongoing biomedical research will change dramatically in the next several years depending on whether the Moon or Mars is the ultimate destination. For questions of astronaut health, the experience base required to support lunar missions lasting from weeks to months is well within the experiences gained on the ISS. Medical issues at a lunar outpost are dominated by radiation exposure and management of sick or injured crew; in an emergency, astronauts could return to Earth in three days. By contrast, health issues for a Mars mission are dominated by the long transit time between Earth and Mars, possibly up to a year, and the inability to return to Earth.204

Medical issues in this case require study of bone loss, muscle deconditioning, nutrition, sensorimotor, and immunological issues. The research priorities are more ambitious with Mars as a destination. Hence, the long-term vision for human spaceflight has implications for short-term research decisions.

Second, details of hardware development depend on the choice of destination. Hardware requirements for a permanent Moon base differ from those for short lunar sorties followed by a mission to Mars. An example is the ascent engine of the Altair lunar lander, which returns astronauts from the lunar surface. Two types of engines are under consideration: a hypergolic engine (like that on the Apollo lunar lander), which will also be used for the Orion service module; and a liquid oxygen and methane (LOX/CH4) engine, which would be developed separately for the Altair ascent stage.205 If the program focuses entirely on the lunar program, then a hypergolic engine is more affordable because of commonality with the Orion. However, a LOX/CH4 engine will ultimately be desirable, if not necessary, for a human Mars mission.206 If the goal of the lunar program is truly to develop and test hardware in preparation for a Mars mission, then NASA should immediately invest in developing a LOX/CH4 engine. The affordability of the exploration program depends on its long-term goals.207

Third, a Mars mission requires significant technology development that is not at all necessary for the Moon. The challenge of capturing a massive spacecraft into Martian orbit, descending through the atmosphere, and landing on the surface (often abbreviated as entry, descent, and landing, or EDL) is much greater for a human mission than for robotic spacecraft and rovers. The spacecraft used to land the Spirit and Opportunity rovers on the Martian surface had a mass of just over 1 metric ton (2,344 pounds at launch).208 By comparison, a human mission may require as much as 100 metric tons at the beginning of Mars orbit capture, with a minimum of 20 metric tons landing on the surface.209 These order-of-magnitude differences require NASA to investigate aerocapture technologies, where the planet’s atmosphere slows the arriving spacecraft into orbit, and to design new landing systems because the current parachute and propulsion technologies may not work for such a large payload. Because these technologies are not necessary for the Moon missions, NASA today has no significant research under way to develop EDL technologies for a human-scale payload on another planet.

If the nation’s goal is to proceed quickly to Mars, NASA should plan for a more minimalist campaign on the Moon using systems that are to the maximum extent designed for human Mars missions. A recent Planetary Society white paper recommended that “human landings on the Moon should be deferred until after a new transportation and interplanetary flight capability is developed” and suggests instead missions to near-Earth objects such as asteroids.210 This begs the question, however, what is the nation’s goal in exploration? What are the objectives of a program beyond low-Earth orbit, and how do primary and secondary objectives inform the current lunar program versus any alternatives?

If a primary objective of human spaceflight is to expand the human experience, then any destination beyond low-Earth orbit might satisfy. The Moon is no less worthy a destination just because twelve men have already walked on its surface. Similarly, international prestige might accrue no matter the planetary body explored. Primary objectives do not specify the destination but instead help select among program options.

To satisfy primary objectives of human spaceflight, a new policy should be more, and not less, ambitious. In developing an expansive human spaceflight program, the nation accepts a cost in lost opportunities for other high-technology ventures and also accepts risks to human life. The costs and risks are too great for the administration to leave the exploration program operating at the edge of viability, faced with the same resource constraints and atmosphere of “too much with too little” that plagued NASA leading up to the Columbia disaster.

Given the imbalance between the goals of the 2020 lunar landing and the current funding profile, any commitment for a Mars mission following the 2020 lunar landings requires a decision on the expected size and duration of a U.S. lunar presence. The concern is that, assuming a constant budget, even after the “gap” between the space shuttle and Orion another gap may occur after the United States returns to the Moon because development of the full lunar outpost may not be affordable without cutting back the utilization period prior to full deployment. A third gap may occur between lunar missions and eventual Mars missions because of the lack of a transition strategy between the Moon and Mars and because of the need for developing largely custom Mars exploration systems.

Additional objectives, such as prestige gained from continued technical superiority in space, or forging an international partnership in space after the ISS-era, may also motivate the national leadership. A program focused merely on the next lunar landing, without a clear articulation of the long-term goals and primary objectives of the endeavor, would not represent a coherent long-term program. The Constellation program would look less like “Apollo on steroids” and more like just Apollo.

  • A new human spaceflight policy should clarify the expected size and duration of a U.S. lunar presence and the balance between the Moon, Mars, and other destinations in exploration programs.
  • To satisfy the primary objectives of human spaceflight, a new policy should be more, and not less, ambitious.
  • The administration and Congress should review the Constellation architecture to ensure compatibility with long-range exploration missions (in particular, human Mars missions). Even if doing so means somewhat easing the 2020 deadline for lunar return, NASA must ensure that the new architecture provides a solid foundation for the next generation of human spaceflight.

The Role of Robotic and Remote Vehicles

We have described the expansion of human experience as the core of exploration and exploration as a primary objective of human spaceflight. At first glance, and in a historical sense, this expansion of human experience seems to dictate direct human presence. But the nature of human experience is itself changing here on Earth as it expands into a whole range of new technological possibilities.211 Our “experience” of the world increasingly maps onto communications networks and remote presence through video, listening, even email and social networking. A new generation growing up with these technologies may not take for granted the old adage that there is something special and unique about “being there”—or at least they may not accept that “being there” necessarily involves having one’s body physically in a place. Young Americans, interested in the idea of remotely controlling robots on the Moon or Mars, make “a direct link between teleoperation of Mars and Moon robots and exploration.”212

Space exploration has always embodied a mix of human beings and machines. Since the first probes were sent into orbit in the 1950s, machines have telemetered their “presence” to human beings on Earth as they have explored Earth orbit, the Moon, Mars, and far, far beyond. The Viking landers on Mars in the 1970s sent back images that gave a palpable sense of the Martian terrain and transformed the abstract planet into a place that human beings had seen. Shuttle astronauts describe the close collaborations between the shuttles’ Canadian-built robotic arm and human spacewalkers.213 More recently, the Mars Exploration Rovers Spirit and Opportunity have sent back images and data, and provided explorations and stories to millions on Earth, from professional scientists to schoolchildren. The rovers’ websites have been among NASA’s most popular. These “robotic” explorers are really telerobots, interacting in near real-time with human beings on Earth who explore the solar system through them.214

A rule of thumb within the Mars rover group has been that what it took a rover to do in a day, a human could do in thirty seconds. But no one has proposed sending human beings to Mars simply because they are faster at accomplishing human tasks. And yet NASA still divides its “human” programs from its “robotic” ones, beginning with the distinctly separate engineering cultures of the Johnson Space Center, center of human spaceflight, and the Jet Propulsion Laboratory, center of remote space exploration. Amid the discussion of the human return to the Moon, NASA has not articulated a vision for extensive remote exploration using rovers as a precursor.

What is the best, most extensive remote robotic rover that could be built for operation on the Moon? Such a vehicle would be complete with the latest video and telemetry connected to immersive interface environments on the ground, combined with the best remote manipulators technologically feasible for collection and analysis of samples. Why is such a vehicle not roving the Moon today? The closest vision for such a vehicle has come not from NASA but from the Google Lunar X PRIZE.

Perhaps the human spaceflight cultures within NASA have underemphasized the mixes of robotic and human exploration out of anxiety that the human presence might be overshadowed by remote presence. By contrast, such combined human/robotic missions should serve to underscore, not question, the benefits of direct human presence. A human presence in space truly justified by primary objectives ought to be robust to, and indeed enhanced by, the most advanced technologies of remote presence in space and on the ground. Human exploration missions, as expansions of human experience, should communicate those experiences with the highest possible fidelity to millions of people on the ground.

  • To take full advantage of the human-experience dimension of exploration, NASA’s return to the Moon should aggressively employ robotics, not only as precursors but also as intimate partners in human missions. Telerobotics, remote presence, and participatory exploration will bring the lunar surface to broad populations of professionals and the public and will help redefine the nature of exploration.

Renewing Global Leadership

International prestige, whether in a spirit of competition or cooperation, has been a primary objective of human spaceflight from its inception. During the Cold War, President Kennedy clearly supported the Moon program as a competitive race against the Soviet Union. Recent statements from both the Bush and Obama administrations that recommend collaboration highlight how the international dimension of human spaceflight continues to hold value. During Apollo, the United States ran the program with few opportunities for the involvement of other nations. Today, international cooperation has become a backbone of both the shuttle and ISS programs, and the United States now has a long history of collaboration with the European, Japanese, Canadian, Russian, and other space agencies.

Most countries’ space programs contain nationalistic rhetoric, but most also recognize the benefits of cooperation. Still, other factors, particularly diplomatic relationships and foreign policy goals, clearly influence the balance between cooperation and competition. Russian experience with long-duration orbiting facilities has clearly benefited the ISS project. However, the partnership with Russia was based on more pragmatic foreign policy objectives. Cooperation also does not imply an equal sharing of costs and responsibilities: the United States clearly has contributed more to the ISS than its partners, even though all share in the assembled facility. When foreign policy goals and material contributions do not support collaboration in space, obtaining a competitive advantage may yet be an objective for human spaceflight.

In light of this analysis, what is a model for U.S. leadership in global human spaceflight in the future? We recommend against reviving the Cold War model of the “space race,” which will serve only to put U.S. space policy in a reactive mode. Primary objectives of exploration, national pride, and international prestige do not dictate exclusively national programs, and in the United States a program’s international dimensions remain critical for political support. Moreover, human spaceflight is sufficiently difficult and expensive that international collaboration may be the only way to accomplish certain goals. The United States does not have a monopoly on technology and innovation in the spaceflight arena. International collaborations in human spaceflight have not always reduced costs for the United States, and have sometimes increased them, but such partnerships may well be justified on their foreign policy goals or technology benefits more than for cost savings.

For example, a sustainable partnership with Russia would involve taking into account their interest in prolonging the service life of the ISS until 2020 and cooperating on transportation elements of the lunar and Mars programs. Russia might contribute to the development of alternative transportation architectures that are not on the critical path of the U.S. lunar program.215

A successful, sustainable partnership with Russia could ensure that the research potential of the ISS is achieved and that the United States shares some costs and risks. Russian vehicles might provide additional rescue and transportation options, which would reduce risk for U.S. missions. The Russian space establishment would have a vested interest in continued collaboration with the United States and would be more likely to take effective steps toward preventing proliferation as its space industry consolidates and is brought under tighter centralized control.

The United States has a spectrum of options regarding China. Analysts suggest three possible options for U.S. space policy with respect to China: (1) continue the current policy of noncooperation; (2) engage China in gradual, step-by-step cooperative efforts; or (3) propose a “grand bargain,” a comprehensive settlement of all major issues in military, commercial, and civil uses of space.216 Each of these paths has a variety of strengths and weaknesses. For example, would continued noncooperation promote healthy competition or needlessly encourage a Chinese domestic space industry? Would close cooperation encourage further openness about the Chinese space program and reduce the risks of unilateral provocative actions such as the January 2007 Chinese antisatellite test? Or would it add needless costs to a U.S. program with little tangible security benefits? A deep exploration of these issues is beyond the scope of this paper and requires a close collaboration between human spaceflight experts and analysts of Chinese politics and security policy, as well as knowledge of the political and cultural dimensions of human spaceflight.

Inviting China to participate in the ISS, either as a visitor or a full partner, is the most concrete, immediate option for collaboration.217 Again, options range from flying a Chinese yuhangyuan on existing systems to the ISS, to full options for docking Shenzhou spacecraft to the ISS on a regular basis. Such collaboration would pose technical and safety challenges, as well as questions of technology transfer. Chinese participation in the ISS would require radical revision of the current situation of noncooperation between the United States and China and would pose significant political hurdles on both sides. Setting it as a prospective goal, however, might help structure a series of “small bargains,” gradually engaging China in a widening range of cooperative space activities. While technical, safety, and security issues could be gradually worked out, China’s participation in the ISS would ultimately be a political rather than a technical question.

Any movement on the U.S. relationship with China in human spaceflight must be nuanced by consideration of the larger relationship, particularly regarding commerce, human rights, and national security. Still, by pursuing cooperation, the United States could reassert its role as the leader of global human space efforts, avoid a costly lunar space race, and help avert a dangerous space arms race. China would meet its goals of displaying technological prowess and raising national prestige by engaging with the world’s greatest space power.

India offers even greater opportunities for supporting United States primary objectives in spaceflight. A pragmatic option for NASA would be to build upon current exchanges in space science and applications missions to leave the door open for potential cooperation in selected areas of human spaceflight technology. As an instrument of foreign policy, the current “nuclear deal” has closely aligned India and the United States on matters of nuclear energy and advanced technology. Space is but one component of this link.

Although the balance between cooperation and competition with other nations in human spaceflight remains dependent on larger foreign policy issues, human spaceflight provides an effective diplomatic tool for the United States to use to further the primary objective of global leadership.

  • International partnerships in human spaceflight represent an ideal use of science and technology to advance broad human goals and bring nations together around common values.
  • The United States should reaffirm its long-standing policy of international leadership in human spaceflight and remain committed to its existing international partners. Leadership need not be defined only as “first, largest, and in charge,” but should also represent foresight in building new relationships and collaborations and in setting an example for human spaceflight as an open, civilian enterprise. Given the public enthusiasm for human spaceflight around the globe, a clear perception of the United States as collaborating with other countries to accomplish goals in space would have far-reaching benefits.
  • The United States should invite international and commercial partners to participate in its new exploration initiatives to build a truly global exploration effort.
  • Collaboration with Russia would bring tangible benefits to the Russian space program, possibly influencing Russian public opinion in favor of collaboration with the United States in space and potentially in other areas.
  • The United States should begin engagement with China on human spaceflight in a series of small steps, gradually building up trust and cooperation. Despite technical and political hurdles on both sides, such efforts could yield benefits for U.S. primary objectives. All would entail revision of the current situation of noncooperation between the United States and China.
  • NASA should actively engage the Indian Space Research Organization to develop possibilities for a sustainable partnership in human spaceflight in the 2015 to 2025 time frame, particularly if India chooses to embark on human lunar missions in the post-2020 time frame.


178. John M. Logsdon, “The Space Shuttle Program: A Policy Failure?” Science 232 (1986): 1099–1105. NASA, using early, overly optimistic flight rates, originally estimated the design life of each orbiter to be one hundred missions over approximately ten years. By number of missions, the three remaining orbiters have flown only a quarter of their design lives; however, NASA has operated them for nearly three times longer than expected. As of September 2009, Discovery has flown thirty-seven missions over twenty-five years (first flight in 1984), Atlantis has flown thirty missions over twenty-four years (first flight in 1985), and Endeavour has flown twenty-three missions over seventeen years (first flight in 1992).

179. CAIB Report, 211; emphasis in original.

180. John M. Logsdon, “‘A Failure of National Leadership’: Why No Replacement for the Space Shuttle?” in Critical Issues in the History of Spaceflight, ed. Dick and Launius, 293.

181. CAIB Report, 209.

182. Scott Pace, “The NASA Constellation Program and Post-Shuttle Transition” (seminar in Space, Policy, and Society, Massachusetts Institute of Technology, Cambridge, Massachusetts, May 5, 2008).

183. Gary Kitmacher, ed., Reference Guide to the International Space Station (Washington, D.C.: NASA, 2006),

184. Ibid.

185. “NASA Advisory Council Space Station Utilization Advisory Subcommittee Meeting” (meeting report, Center for Advanced Space Studies, Houston, Texas, July 28–30, 2004).

186. House Committee on Science and Technology, NASA’s Fiscal Year 2009 Budget Request, 110th Cong., 2nd sess. (February 13, 2008).

187. Michael D. Griffin, “Why We (Still) Need to Retire the Shuttle,” Space News, October 20, 2008.

188. The COTS A option is for launching unpressurized cargo to the ISS; COTS B is for launching pressurized cargo; COTS C is for launching and returning pressurized cargo to Earth; and COTS D is for crew launch and return.

189. Becky Iannotta, “Shuttle Extension Options Have Common Denominator: High Cost,” Space News, January 5, 2009.

190. Alvar Saenz-Otero, “Design Principles for the Development of Space Technology Maturation Laboratories aboard the International Space Station” (Ph.D. diss., Massachusetts Institute of Technology, 2005).

191. NASA, The National Aeronautics and Space Administration (NASA) Research and Utilization Plan for the International Space Station (ISS) (NASA, June 2006),

192. NASA, The Vision for Space Exploration.

193. National Research Council, Review of NASA Plans for International Space Station (Washington, D.C.: National Academies Press, 2006).

194. NASA Authorization Act of 2005, Public Law 155, 109th Cong., 1st sess. (December 30, 2005).

195. National Research Council, Review of NASA Plans for International Space Station.

196. National Research Council, A Constrained Space Exploration Technology Program: A Review of NASA’s Exploration Technology Development Program (Washington, D.C.: National Academies Press, 2008).

197. One example of a pathfinder experiment involves development of a potential Salmonella vaccine. See NASA, “National Lab Pathfinder-Vaccine-1A (NLP-Vaccine-1A),” August 5, 2009,

198. Pace, “The NASA Constellation Program and Post-Shuttle Transition.”

199. NASA, NASA Report to Congress Regarding a Plan for the International Space Station National Laboratory (NASA, May 2007),

200. NASA Authorization Act of 2008, Public Law 442, 110th Cong., 1st sess. (October 15, 2008).

201. Abbey and Lane, United States Space Policy,6.

202. W. W. Mendell, “Meditations on the New Space Vision: The Moon as a Stepping Stone to Mars,” Acta Astronautica 57 (2005): 676–683; and Laurence R. Young, “Using the Moon to Learn About Living on Mars,” ASK Magazine, no. 32 (Fall 2008): 34–35,

203. The Planetary Society, Beyond the Moon: A New Roadmap for Human Space Exploration in the 21st Century (Pasadena, Calif.: The Planetary Society, 2008),

204. For a single mission, cosmonaut Valeri Polyakov has the record of 437 days in orbit. An opposition-class (short-stay) Mars mission would last 661 days. NASA’s preferred long-stay, conjunction-class mission would last 905 days.

205. Clinton Dorris, “Lunar Program Industry Briefing: Altair Overview” (presentation at Exploration Systems Mission Directorate forum, Washington, D.C., September 25, 2008),

206. A LOX/CH4 propulsion system is significantly better in performance, and methane and oxygen could, in principle, be produced on Mars, eliminating the need to transport ascent propellant from Earth.

207. Paul D. Wooster, Wilfried K. Hofstetter, William D. Nadir, and Edward F. Crawley, “The Mars-Back Approach: Affordable and Sustainable Exploration of the Moon, Mars, and Beyond Using Common Systems,” IAC-05-D3.1.06 (paper presented at the 56th International Astronautical Congress, Fukuoka, Japan, October 17–21, 2005).

208. NASA, “Mars Exploration Rover Mission: The Mission,” n.d.,

209. Wilfried K. Hofstetter, Paul D. Wooster, William D. Nadir, and Edward F. Crawley, “Affordable Human Moon and Mars Exploration through Hardware Commonality,” AIAA 2005– 6757 (paper presented at Space 2005, Long Beach, California, August 30–September 1, 2005).

210. The Planetary Society, Beyond the Moon.

211. Savan C. Becker, “Astro Projection: Virtual Reality, Telepresence, and the Evolving Human Space Experience,” Quest 12 (3) (2005): 34–54.

212. Mary Lynne Dittmar, “Engaging the ‘18–25’ Generation: Educational Outreach, Interactive Technologies, and Space,” AIAA-2006-7303 (paper presented at Space 2006, San Jose, California, September 19–21, 2006).

213. Savan C. Becker, “Rise of the Machines: Telerobotic Operations in the U.S. Space Program,” Quest 11 (4) (2004): 14–39.

214. William J. Clancey, “Becoming a Rover,” in Turkle, Simulation and Its Discontents, 107–127; Zara Mirmalek, “Solar Discrepancies, Mars Exploration and the Curious Problem of Inter-planetary Time” (Ph.D. diss., University of California, San Diego, 2008); and Steven Squyres, Roving Mars: Spirit, Opportunity, and the Exploration of the Red Planet (New York: Hyperion, 2005).

215. Alain Dupas and John M. Logsdon, “Creating a Productive International Partnership in the Vision for Space Exploration,” Space Policy 23 (2007): 27.

216. Theresa Hitchens and David Chen, “Forging a Sino-US ‘Grand Bargain’ in Space,” Space Policy 24 (2008): 128–131; and Johnson-Freese, “A New US-Sino Space Relationship,” 155.

217. “China Hopes to Join International Space Station Project.”