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Lunar exploration illustration
Effective future exploration of the Moon or other destinations beyond low Earth orbit requires development of a suite of technologies that can increase capabilities and lower costs. (credit: Pat Rawlings/NASA)

Future space capabilities for an ambitious civil space program

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There is at present tremendous uncertainty and no little concern regarding the future of human spaceflight in particular, and global space programs more generally. This uncertainty is due in large measure to the recently announced redirection of the US space program. The reasons for those changes are complex and controversial. It is important to appreciate, however, that the principal issues driving the changes are not related to the goals of the US space program. Rather, they are being driven by the anticipated costs of achieving US civil space goals using the toolkit of technologies and systems that are available today. If they were affordable and cost-effective, no one would object to a lunar outpost, a human mission to Mars, or to large new Earth and space science missions. The central challenge for US space science and exploration during this decade revolves around the issue of affordability.

We should not give up on our ambitious goals for space; rather, we must find ways to accomplish ambitious goals far more affordably that can possibly be done with architectural approaches from the 1960s.

One good approach to achieving affordability is to focus. A modest space program—focused on only a few goals—can certainly be affordable and successful. Several countries have followed this approach for decades. A program with modest goals—one that seeks to accomplish less—could be more affordable and far less risky that an ambitious civil space program. However, such an approach would raise a number of inherent strategic issues for the United States.

A modest space program could not support the full suite of important national objectives that we have in space, and it would fail to achieve the profound cultural goals to which Americans aspire in space. Worse, a tightly focused program could readily become vulnerable to scientific or technological “surprise”. The space programs of other nations might well focus on important goals that the US chose not to pursue for reasons of budget—and in due course they might well achieve mission goals and develop novel capabilities that challenge US leadership in space.

A second—and I believe a better—approach to achieving affordability is to innovate. We should not give up on our ambitious goals for space; rather, we must find ways to accomplish ambitious goals far more affordably that can possibly be done with architectural approaches from the 1960s.

The White House and NASA’s new leadership seem to agree. In the recently released NASA budget, there is a robust commitment to a reinvigorated NASA investment in science and technology. This restoration is urgently needed: the budget for civil space advanced technology development has been reduced drastically during the past five years.

However, the future of the US civil space program cannot be science-only, nor can space technology investments be limited to what is known as “technology push” R&D—i.e., technology development for its own sake. The objectives of NASA’s new advanced technology investments should be dedicated to making possible more affordable and sustainable approaches to ambitious space science and exploration programs in the future.

How can this be achieved? What technology investments should be pursued to best enable a wide range of ambitious but still affordable goals for the US civil space program?

The objectives of NASA’s new advanced technology investments should be dedicated to making possible more affordable and sustainable approaches to ambitious space science and exploration programs in the future.

The answer is to direct future advanced technology investments toward the development of critically needed “Future Space Capabilities”, rather than on new technology for its own sake. There are three fundamental capability gaps that must be addressed in order to achieve the goal of affordability: transformational space infrastructures, safe and sustainable human presence in space, and revolutionary autonomy and robotics. Realizing each of these capabilities will require advances in some very specific areas of technology, and risks will need to be taken. However, it has long been known that organizing US civil space technology investments around solving hard systems problems such as these will stimulate far more innovation than any other approach to research and development.

Critical technology challenges

Transformational Space Infrastructures: First and foremost, there is an urgent need to dramatically reduce the cost of owning and operating space systems by at least a factor of 10 while significantly increasing the operational capabilities of those systems. This requires investments in the following technology areas.

  • In-Space Refueling, comprising the capability for cryogenic fluid (e.g., propellant) storage and management, and the safe and efficient transfer of fluids in space
  • Affordable Long-Lived Power in Space, including high-energy and high-efficiency solar electric power generation systems and modular/reconfigurable power management and distribution (PMAD) for use throughout the inner solar system (including on the surfaces of the Moon and Mars), and advanced radioisotope power systems for use in the outer solar system.
  • Reusable High-Energy In-Space Propulsion, which includes both high energy and high efficiency electric/electromagnetic propulsion systems, as well as high energy/high fuel efficiency, re-startable, and deep throttling cryogenic propulsion.
  • High-Strength and Low-Mass Modular Structures, including both systems and materials for modular systems, as well as a range of advanced materials for use in structural systems in extreme environments (including high-temperature environments), as well as tailored features such as self-healing materials.
  • Intelligent Modular Space Systems, comprising redundant and self-reconfigurable modular electronics, low mass, deployable thermal systems, and intelligent interfaces (including wireless interconnects).
  • Reusable Low-Cost Launch Systems, comprising a range of novel approaches in propulsion, structural systems, materials, vehicle avionics, and spaceport operations.

Sustainable Human Presence: Secondly, if ambitious human exploration is ever to be sustainable, it is essential that the expected costs of human presence in space beyond low Earth orbit (i.e., to the Moon, Mars, and accessible deep space targets such as asteroids) be reduced by at least an order of magnitude, while assuring that human operations in space are as safe as reasonably achievable. This capability requires advances in the following areas.

  • Sustainable Habitation Systems, such as low mass, long-life, and re-configurable space habitats (including locally-maintained closed-loop life support systems), that can be readily “restarted” (since human presence is unlikely to be continuous at first).
  • Sustainable, Increasingly Self-Sufficient Human Operations Systems, including extravehicular activity (EVA) systems that can be locally maintained and repaired over indefinite periods of time, and which can be locally upgraded to incorporate new technologies.
  • Radiation Protection, such as extravehicular activity (EVA) systems that can be locally maintained and repaired for indefinite periods of time.
  • Remote Medical Care in Space, including capabilities of the largely autonomous care for illnesses, and treatment of traumatic injuries.

Autonomous Space Operations: Finally, if ambitious science and exploration missions are to be made affordable, then we must move aggressively toward more and more self-sufficient, operationally autonomous systems in space. This third capability will require advances in the following areas.

  • Autonomous Human Mission Operations, including highly effective and increasingly self-sufficient human operations in deep space (without large ground crews for mission operations), with advances in intelligent and self-reconfigurable human mission systems, advanced human-machine interfaces, etc.
  • Lunar and Planetary Resource Utilization, such as extraction, processing, and manufacturing of useful materials (e.g., propellants) and system elements (such as solar arrays or structural elements).
  • Reconfigurable High Bandwidth Communications and Networks, including long-range high-rate communications (e.g., optical communications), reconfigurable local wireless networks.
  • Intelligent Self-Sufficient Robotic Systems, for example highly mobile, dexterous, and autonomous robotics (i.e., advanced versions of conventional “rovers”), as well as UAV-like vehicles, systems, etc.

Why develop these technology areas?

There would be numerous benefits to advancing the areas of technology identified above. For the sake of brevity, the fundamental benefits of the Future Space Capabilities that would result from advancing the above technology areas can be characterized succinctly in terms of three figures of merit that are drivers of space program costs: mission cost due to manufactured hardware, mission cost due to launch, and mission cost resulting from labor during mission operations.

If successful, the technology advancements suggested—and the set of Future Space Capabilities that would result—could make possible a wide range of new, more ambitious space missions.

Mission Costs Due to Manufactured Hardware. The critical issues with exploration mission architecture using existing technologies arise from two primary characteristics: (1) the mission hardware is expended after a single use or a single mission (particularly in-space transportation systems, in-space habitation, etc.), and (2) the mission hardware is very expensive (typically $50,000 to $100,000 per kilogram of hardware—and perhaps much more). In the case of an Apollo-type mission, the mission hardware mass may be in the range of 100,000 kilograms: if that hardware is expended after a single mission, the mission cost due to manufactured hardware cannot be less than $3–5 billion per mission.

Reducing this cost depends on reducing the amount of hardware expended—i.e., increasing the reusability of mission hardware—and reducing the cost per kilogram of the mission hardware. The principal capabilities that allow these objectives to be achieved include (a) affordable refueling of space vehicles in low Earth orbit and beyond, (b) reusable systems, and (c) modularity of system architectures that are used to implement missions (to realize lower manufacturing costs and ease of repair).

Mission Costs Due to Launch. Second only to hardware costs, the cost of Earth-to-orbit launch is the most important driver of mission costs. (Of course, mission launch costs rapidly become greater with increasing distance beyond low Earth orbit.) Typically the cost of launch can be in the range of $10,000 to $20,000 per kilogram, particularly in the case of heavy-lift launch vehicles that are used only infrequently. In the case of an Apollo-type mission, the total mission mass may be in the range of 100,000 kilograms or more (including systems to go beyond LEO); in this case, the mission cost due to launch would be about $1 billion per mission or more.

Reducing this cost depends on reducing the amount of mass to be launched, and increasing the use of low-cost launchers. The principal capabilities that allow these objectives to be achieved include (a) lower mass systems, (b) reusable space systems, (c) increased launch of propellants and systems on lower cost commercial launchers, and (d) early and increasing reliance on in situ resources.

Mission Cost Resulting from Labor During Mission Operations. A final key driver for ambitious future missions is the cost of personnel involved in sustaining engineering and mission operations, particularly for long-duration and/or highly complex missions. For example, in the case of a full time equivalent labor cost of $250,000 per year, if 5,000 or more personnel were involved in mission sustaining engineering and operations, then the mission cost due to labor would be more than $1–1.5 billion per year. For example, if an Apollo-type lunar architecture involved two missions to the Moon per year, the labor cost could easily be more than $500–700 million per mission.

Reducing this cost depends on reducing the number of personnel involved in each mission’s operations and increasing the number of missions per year, while diversifying the responsibilities of sustaining engineering personnel. The principal capabilities that allow these objectives to be achieved include (a) increased systems autonomy, (b) increased use of robotic systems, and (c) increased bandwidth in communications, coupled with use of wireless reconfigurable networks of local systems.

Benefits enabled by this approach

If successful, the technology advancements suggested—and the set of Future Space Capabilities that would result—could make possible a wide range of new, more ambitious space missions. Of course, specific programs would require specific budget decisions. However, in general more affordable and sustainable systems and operations would allow ambitious goals to be pursued without a priori dramatic ongoing increases in the overall US government budget for the civil space program. Some examples of the types of missions that could be realized include the following.

Large Platforms in LEO and Beyond, including the affordable deployment of large platforms in low- to mid-Earth orbits, in geostationary Earth orbits (e.g., fiber-equivalent communications satellites, hyper-spectral/large aperture Earth observing platforms), to Libration Point missions (e.g., telescopes, Sun-Earth connection spacecraft), or beyond.

Space Assembly, Maintenance and Servicing Missions, including servicing of large platforms in geostationary orbits, such as Earth-observing systems (e.g., SAR), or commercial platforms.

Affordable Human/Robotic Missions Beyond Low Earth Orbit, including missions to the Earth-Moon and Sun-Earth Libration Points (e.g., for the deployment of large space telescopes), diverse lunar missions (including both sorties, Mars test campaigns, or an outpost), eventual human/robotic Mars missions, and missions to other deep space targets of opportunity.

Permanent Human Activity on the Moon and Development of Lunar and Other Space Resources, including establishing low-cost robotic networks on the Moon, pursuing lunar surface resource development, and enabling both permanent long-range transportation capabilities on the lunar surface and low cost launch from the Moon, etc.

Ambitious Robotic Science Missions, including Mars sample return or a robotic surface outpost, staging of revolutionary deep space missions (e.g., Europa landers, or Titan surface rovers), and others.

Novel Commercial and Science Space Missions, including completely new options, such as lunar surface telescopes, lower cost public space travel, space solar power systems, and others.


There are, of course, additional technology investment areas that are deserving of attention by the revitalized NASA space technology R&D budget that has been proposed beyond those mentioned above. These include R&D to develop extreme environment electronics and computing, novel materials for continuing innovation in sensors and detectors, and others. Also, there must be room in the budget for purely “out of the box” studies and technology research—resources set aside for advanced concepts activities that provide the conceptual “seed corn” for defining the new missions, and even the new goals of the civil space program of the future. And, there must be an adequate investment in education and outreach to assure that NASA’s space technology and science investments inspire students from kindergarten to graduate school to pursue careers in engineering, the sciences, and space exploration.

However, even in these challenging economic times the US civil space program must remain dedicated to achieving ambitious goals if it is to fulfill the purposes for which it was established more than 50 years ago. By focusing future civil space technology investments on creating ambitious but affordable Future Space Capabilities, including those delineated above, we can still fulfill those purposes of 50 years ago… and more.