Enhancing Military and Commercial Spacepower through Nuclear

Abstract

Strategic competition among great powers is increasing the importance of maintaining and increasing U.S. national power in outer space. The United States, Russia, and China are all pursuing space reactors and nuclear rockets but spacepower and associated theories have yet to fully consider how space nuclear technologies enable national space capabilities. Similarly, the role of space nuclear energy in the Department of Defense (DOD) – namely, the U.S. Space Force planning remains unclear. This article examines space nuclear energy’s contribution to U.S. national power. It reviews Cold War history and current plans to develop space nuclear energy. It evaluates emerging spacepower theories and offers an initial framework of how nuclear energy builds national spacepower. Finally, it concludes by reviewing recent U.S. policy developments and offering a pathway for the United States to lead in space nuclear technologies. This involves building a supportive industrial base for civilian applications, which can accelerate innovation, build capabilities, and deliver technology optionality. Meanwhile, the DoD will need to design effective procurement, management, and regulatory systems for military space applications. Further research is needed to evaluate how space reactors and propulsion can support soft and hard power, as well as the geopolitical implications of their development.

Introduction

Space nuclear power systems may be a keystone basis for long-term and high energy activities in outer space. The tyranny of distance and time makes energy density and reliability essential to space operations. Refueling with chemical fuels is expensive and not currently practical. Solar panels power most existing space systems, but have performance limitations in deep space. Nuclear power systems offer distinct advantages for national space operations. Radioactive decay powers some of the most iconic space missions of all time, from deep space probes to Martian rovers. Fission reactors can support high-energy space applications, including lunar science bases and private space mines. Nuclear rockets can outperform chemical rockets and offer maneuver advantages in deep space.

Strategic competition among great powers is driving a renaissance in planning for space nuclear power systems. The growing importance of the space domain for terrestrial military competition and emerging commercial uses of space make maintaining and expanding spacepower a prime national concern. The United States, Russia, and China are all exploring how space reactors and nuclear rockets can support commercial and military missions in outer space. However, relatively little work has examined how space nuclear technologies comport with spacepower theories and national strategies.

This article explores the intersection between space nuclear power, spacepower, and astropolitics. It reviews space nuclear’s history during the Cold War and describes current commercial and government plans. The article presents three novel contributions. First, it describes how spacepower and astropolitics generally do not account for the unique capabilities of space nuclear energy. Second, this article argues that spacepower theories should consider space nuclear technologies and provides an initial analysis. Third, it evaluates how the emerging advanced nuclear industrial base and federal space procurement can support commercial, civil, and military space applications, building on recent executive branch policy.

Space nuclear technologies and their operational implications

Mission planners have long considered nuclear power options for powering, heating, and propelling spacecraft.[1] Nuclear energy is advantageous because of its energy density – it contains the most potential energy per mass of any energy source. In the next several decades, it is likely the only option for megawatt-scale electricity generation. Nuclear has a high level of reliability and availability and can operate in shadowed regions such as lunar polar craters. Three nuclear mechanisms can be used for spacecraft energy: radioactive decay, fission, and fusion (although fusion remains a long-term technology).[2]

Spacecraft use radioactive decay of isotopes for heating and power. Radioactive decay of an unstable isotope produces heat in a radioisotope heating unit (RHU) and produces heat and electricity in a radioisotope thermoelectric generator (RTG).[3] Although RTGs typically cost more than solar alternatives, they are able to conduct more missions with more instruments over longer time frames.[4] The most common radioisotope fuel is Plutonium-238 (Pu-238) due to a long half-life, manageable radiation, and relatively high heat production.[5] Less commonly, Polonium-210 was used by the Soviet Union for the Lunokhod lunar landers.[6] While RHUs and RTGs have high reliability due to a lack of moving parts, they produce low amounts of power (historically less than one kilowatt), generally limiting them to robotic exploration.

Comparably nuclear fission reactors can support power consumption at the kilowatt- or even megawatt-scale, enabling advanced operations and crew support. Like terrestrial reactors, space reactors produce heat through controlled fission of uranium-235 atoms, converting heat to electricity.[7] In the space operating environment, however, reactors do not use the light-water technology that dominates terrestrial nuclear power, they instead use other fission and thermal cycles. Beyond producing heat and electricity, fission reactors can also provide nuclear electric propulsion when paired with an ion drive.[8] These low thrust, high specific impulse engines have slow acceleration but can reduce long-distance travel times. 

Designers can also adapt nuclear reactors to directly expel a heated propellent in nuclear thermal propulsion (NTP). Commonly called nuclear rockets, fission NTP systems have high thrust and a specific impulse two to three times that of conventional chemical rockets.[9]These systems could reduce Mars mission durations to 2 years or less, and provide maneuverability in cislunar space.[10] Beyond near-term technologies, more exotic forms of space nuclear propulsion include fusion, fission fragment rockets, and nuclear pulse propulsion.[11]

Using nuclear energy for space applications faces several limitations, especially risks of accidents releasing radioactive materials on Earth during launch or reentry. A recent study contracted by NASA on inadvertent reentry found that each scenario – burnup in the atmosphere, intact impact, and scattered impact – brought operational concerns and required design mitigation.[12] After operations in space, nuclear systems need decommissioning and spent fuel storage. Historically, the United States and Soviet Union disposed of all fission reactors operated in space in “graveyard” orbits, in upper low Earth orbit (LEO) or medium Earth orbit, to prevent reentry to Earth.[13] However, rising amounts of space debris are leading to new concerns about these orbits, with a defunct Soviet nuclear-powered satellite colliding with another satellite in 2009.[14]

The primary limitations face space nuclear technologies may be security and nonproliferation, especially related to the use of highly enriched uranium (HEU) in space reactors. National and international law strictly controls HEU because it can be directly used in a weapon. There are three primary, interrelated concerns with HEU-powered spacecraft: security, launch accidents, and precedence.[15] HEU presents security concerns as it could obtained by non-state actors or rogue states in the unlikely event of a launch accident that distributes HEU on Earth.[16] More pressing, the use of HEU for civil space activities goes against U.S. policy to limit HEU in all civil applications and raises concerns about establishing a bad precedent.[17] Unlike terrestrial reactors, where low enriched uranium (LEU) can readily be used with limited performance implications, space reactors are mass constrained. LEU designs thus have performance disadvantages compared to HEU.[18] These limitations are pronounced for nuclear thermal propulsion as they can reduce the mass-to-thrust advantages of nuclear rockets compared to chemical propulsion.[19] However, commercial entities are better suited to developing LEU designs and LEU designs could be cheaper in the long-term.[20] Considering HEU limitations, most near-term U.S. space reactors are likely to use high-assay low enriched uranium (HALEU), with enrichments of up to 19.9% uranium-235, to maximize energy per mass.[21] They are also likely to use the fast neutron spectrum, enabling fission of uranium-238 and increasing overall fuel efficiency.

Historical and prospective roles of space nuclear energy in national space activities

With the nuclear and space ages starting within a span of two decades, the early Cold War featured significant space nuclear activities by the United States and Soviet Union. As early as 1951, the U.S. Air Force worked with the Atomic Energy Commission (the precursor the Department of Energy and Nuclear Regulatory Commission) to explore powering satellites with space reactors.[22] The United States investigated each type of nuclear space system, ultimately test flying the SNAP-10A reactor in the 1960s and using RHUs and RTGs to support multiple early space missions. The United States also designed and tested a nuclear rocket, Nuclear Engine for Rocket Vehicle Application, but never did test flights. These early uses of space nuclear power, developed through close collaboration between Department of Defense (DOD) and the Atomic Energy Commission, were driven by both the space race and the arms race.[23] American space nuclear development efforts continued until the end of the Cold War. The 1980s Strategic Defense Initiative for missile defense envisioned nuclear power as an enabling technology for space-based assets. Megawatt and multi-megawatt space reactors were the only power systems able to supply projected energy demands for space-based laser weapons.[24] 

Contemporaneously, the Soviet Union pursued multiple space nuclear energy technologies during the space race and subsequent activities. The two Soviet lunar landers, Lunokhod-I and Lunokhod-II, utilized RHUs to survive lunar night. The Soviet Union also developed nuclear rockets but never flight-tested them. The greatest amount of Soviet space nuclear activity involved the use of space reactors to power satellites tracking U.S. naval vessels on the world’s oceans.[25] During the 1970s and 1980s, the Soviet Union launched dozens of these reactors. Following a launch accident and an international incident when a reactor accidently reentered and crashed in Canada, and in light of their contemporary provocative military nature, Steven Aftergood proposed a ban on the use of space reactors in any Earth orbit.[26] As with SNAP-10A, Soviet reactors were stored in graveyard orbits at the end of their lifetimes.

Radioisotope power sources were essential for previous American scientific missions. Some of the most important space missions in history used RHUs and/or RTGs, including Apollo, Voyager, Pioneer, and New Horizons.[27] Radioisotope energy has heated or powered most Mars rovers, including the ongoing Perseverance mission which could extract the first Martian regolith samples for Earth return. The Dragonfly mission has an even more ambitious plan, with an RTG powering a drone quadcopter to explore Saturn’s moon Titan.[28] The combination of a power source able to survive Titan’s harsh conditions and flight technologies will enable Dragonfly to cover more area than any lander in history. However, the reliance of American RTGs on Plutonium-238 is a limiting factor for deep space missions as Pu-238 is a nuclear weapons byproduct and inventories have fallen since the end of the Cold War. The Department of Energy (DOE) is now producing Pu-238 directly but can only support several missions per decade.[29]

NASA is studying how nuclear fission reactors can power uncrewed and crewed missions. In 2018, DOE and NASA collaborated to produce Kilopower, the first entirely new reactor design built and operated in the United States in decades. [30] Designed to produce 1-10 kilowatts-electric using HEU, Kilopower was successful due to an engineering process that emphasized getting to an operating reactor as quick as possible, avoiding the development fate of earlier U.S. space reactors. Following Kilopower, NASA is turning to commercial providers for reactor innovation, with an expected solicitation for commercial entities to build a reactor for flight testing on the Moon by 2027.[31]

Commercial space fission designs are emerging in the United States due to both renewed government interest and development of private commercial space activities. At least four companies are designing space reactors or nuclear rockets while another three American nuclear developers have designs that could be adapted to space.[32] Commercial companies can produce space and nuclear technologies at lower cost and development risk than government entities.[33] Some of these designs are intended to serve private “NewSpace” activities such as space manufacturing, Mars settlement, space stations, or space mining.[34] The most promising of these, and game changing, may be mining for space resources on the Moon or asteroids. Water produced from the Moon or asteroids can enable production of propellant in-space, enabling refueling and lowering space transportation costs (notably, electrolysis of lunar water can produce hydrogen, the preferred propellant for NTP). The energy density and high reliability of nuclear reactors make them natural, and perhaps necessary, candidates for private space mines.[35]

The United States is pursuing two separate nuclear rocket approaches which could greatly augment its soft and hard spacepower. NASA is investigating NTP to propel crewed missions to Mars and has begun receiving proposed designs from vendors.[36] Meanwhile, the Defense Advanced Research Projects Agency (DARPA) is progressing on a nuclear rocket project called Demonstration Rocket for Agile Cislunar Operations (DRACO).[37] As the name implies, the rocket is intended for deep space operations and is notable as DARPA plans to develop DRACO through flight testing, which would make it the first nuclear rocket to reach space.

Russia and China are also pursuing nuclear power sources for outer space applications, although there is less publicly available information concerning these plans. For the last decade, Rosatom State Nuclear Energy Corporation has worked on a nuclear-reactor powered rocket engine to provide electricity and thrust for deep-space missions.[38]Russia appears to be developing a nuclear reactor for a satellite to power space-based electronic warfare capabilities.[39]China’s ongoing lunar lander programs feature radioisotope energy sources, critical to survive the lunar night. Notably, these initial radioisotope systems were supplied by Russia, an early indication of emerging Russia-Chinese space cooperation.[40]When the Chang’e-5 mission returned the first lunar surface samples to Earth in 50 years, this radioisotope energy boosted Chinese soft power and contributed to realization of Chinese space goals and President Xi’s “Space Dream.”[41]China Aerospace Science and Technology Corporation recently indicated that it is researching a nuclear-powered space shuttle, with a breakthrough expected before 2040.[42]In light of the U.S. development of NTP for military applications, China’s strategy to become a preeminent power in space could drive sustained interest in Chinese NTP.[43]

Integrating space nuclear into spacepower theories and astropolitics

Theories of spacepower remain relatively new and are only beginning to grasp the nature of military and other power in the space domain. Spacepower is considered an applied aspect of security studies, international relations, and astropolitics.[44] For present purposes, it is worth identifying two major themes. First, many theorists draw upon sea and air power for inspiration, with theorists often citing Mahanian seapower’s focus on maritime commerce as an example for how spacepower could emerge from space commerce.[45]Second, there is a distinction between “brown water” spacepower, which views space as a domain primarily focused on Earth orbits to support terrestrial activities, and “blue water” spacepower, which views space activities as extending into cislunar space and beyond.[46]

Scenario based analysis can provide a useful framework to interrogate these theories of spacepower. Peter Garretson describes two visions of space conflict in the 2030s: Earth-based conflict leading to space actions, and space conflict dealing with primarily space-based causes.[47] The former envisions conflict within LEO and geostationary orbit, reflecting its earth-centered nature. In this case, nuclear reactors could matter to the degree they support unique orbital space capabilities while nuclear rockets could have minor maneuver advantages. In the second vision, conflict could occur in cislunar or deep space due to space resources or other interests, with nuclear rockets, nuclear electric propulsion, and reactors each bringing distinct benefits. A 2019 Aerospace Corporation report reviews a broader range of competing theories about the nature of space warfare and its implications for defense planning.[48] This report presented six schools of thought for space conflict for the space economy and balance of power in 2060:

· Space Control First

· Enable Global Missile War

· Keep the Plumbing Running

· Frictionless Intelligence

· Nukes Matter Most

· Galactic Battle Fleet

The treatment of space as a warfighting domain and associated technology planning depends on which of these competing (and occasionally complementary) schools of thought planners adopt. Of the six schools, “Space Control First” and “Galactic Battle Fleet” are most likely to require space nuclear rockets for strategic advantage. Similar reports also outline different scenarios, ranging from orbital focuses to cislunar space and beyond, that would bring alternative implications for nuclear technology development.[49]

To the degree spacepower theories consider technology, they often focus on near-Earth space capabilities. Essential elements of initial spacepower are navigational, communication, missile warning, intelligence, surveillance, and reconnaissance services from satellites, foundational cross-domain technologies that enable precision strike on land and at sea. As additional nations gain space access, many ‘nascent’ or ‘middle’ space powers have these services for at least commercial purposes and sometimes military.[50] Increasing reliance on outer space surveillance and communications by global militaries means the most disruptive and threatening new space technologies are counterspace capabilities, which provide offensive options for great powers and other space actors.[51] Space situational awareness technologies form the basis for anti-satellite missiles, co-orbital space weapons, cyber capabilities, and high-energy ground-based weapons that can disrupt or destroy enemy satellites.[52] These technological analyses often neglect how nuclear energy can build space-based capabilities or power ground-based high energy weapons that target satellites.[53]

Despite their importance to national space capabilities, most of the referenced documents, reports, and books do not mention space nuclear energy and when they do it is often in passing. The limited existing analysis that exists focuses primarily on nuclear propulsion as opposed to power reactors. In reviewing how propulsion supports space superiority, Spacelift 2025 describes how nuclear electric propulsion and nuclear rockets could deliver orbital transfers and other near-Earth operational requirements.[54] In particular, one study that specifically investigated nuclear reactors examined how political challenges could be addressed.[55] Furthermore, in “Developing National Power in Space,” Brent Ziarnick examines multiple aspects of the relationship between nuclear propulsion and national space power, noting that nuclear’s expected performance benefits could open up the solar system beyond cislunar space to broad commercial activities.[56] His analysis describes how progression along multiple types of propulsion, from first generation fission rockets to fourth generation fusion rockets, would grow capabilities. Notably, Ziarnick proposed that a nuclear rocket would be well suited for a space guard type entity (modeled after the U.S. Coast Guard) performing operations such as in-space rescue, emergency repair, and law enforcement. In highlighting how new material supply can benefit spacepower, he also highlights the importance of finding fissile or fusion fuels in space for nuclear rockets. 

In response to China’s space nuclear ambitions, Garretson proposes that Department of Energy (DOE) lead American space technology research, including nuclear rockets, space resources for conventional rockets, and lunar Helium-3 extraction.[57] Over the next two decades, space nuclear may be more important for building soft and economic power through civil and commercial activities than for military applications. Space exploration and research by NASA is an “obvious, high-profile, high-leverage mechanisms for exercising soft power” and building overall national influence.[58] 

Nuclear power is an enabling technology for these efforts, especially for emerging space applications. The U.S. National Space Council report “A New Era for Deep Space Exploration and Development” highlights the importance of nuclear power sources for scientific research, economic activities like space resources, and to transport astronauts to Mars.[59] If nuclear power is foundational to space resources and if space resources are foundational to expanded economic activity in outer space, nuclear power is a necessary technology for sustainable space commercial development.

Greater research is needed into the spacepower and astropolitical characteristics of space nuclear energy given its transformational capabilities for civil, commercial, and military applications. The historical decisions by the United States and Soviet Union during the Cold War, and the modern plans by the United States, Russia, and China to pursue space nuclear energy, underscore its foundational nature to building spacepower. Nuclear rocket capabilities could make NTP a requirement for long-term space superiority in cislunar and deep space. Whether its advantages are likely to be decisive remains unclear, especially with technology and operational uncertainty. In Earth orbit, nuclear energy technologies could be foundational to high-energy applications such as space weapons. Further research is needed on space weaponization enabled by nuclear energy (ground-based and space-based) as it could be destabilizing for nuclear warfare and space deterrence. Additional research is also needed on the economic and soft power benefits that a nation gains from missions and activities enabled by space nuclear energy.

Public policy for an enduring space nuclear industrial base

The United States needs a national strategy to develop a strong space nuclear industrial base to maintain American competitiveness and leadership in space,  in particular cislunar and deep space. There should be substantial skepticism that current efforts to develop space reactors and nuclear rockets will be successful or inevitable given the sporadic and generally unsuccessful nature of most space nuclear development programs to date. Space nuclear energy is part of both the nuclear and space sectors, strategic and technically complex industries. American success in these and related industries is needed in strategic competition among great powers.[60] The long timeframes involved with space nuclear technology development, especially to reach advanced and mature designs, means that continuing activities are necessary to ensure the United States is not surpassed by Russia and China. Sustained industry and government support is needed for technological superiority, as is a conducive policy framework.[61]

Terrestrially, the U.S. commercial nuclear sector is struggling to retain global leadership amid greater economic competition from Russian and Chinese designs. Private innovators are rising to the challenge and the United States now hosts dozens of companies pursuing advanced reactor designs and fuels, including for microreactors most suitable to be adapted for space applications.[62] Beyond several companies explicitly pursuing space nuclear designs, two commercial fuel developments, HALEU and tri-structural isotropic particle (TRISO) fuel, will underlie any domestic space nuclear program.[63] With limited enrichment capability, the United States may struggle to produce sufficient HALEU and commercial vendors may be forced to the only alternative global supplier, Russia. Any approach to integrating space nuclear energy into spacepower theories must recognize and incorporate domestic nuclear innovation capabilities. A strong domestic industry that supports innovation in reactor designs, fuels, and supply chains for terrestrial use is a prerequisite for advanced space nuclear technology development. More broadly, frameworks that analyze the benefits of nuclear power capabilities on national security should incorporate the potential benefits to spacepower. In the United States, the civilian nuclear power sector supports military nuclear programs though technological risk mitigation, procurement assurance, and human capital calculated to be worth tens of billions of dollars to U.S. national security.[64]

Robust and diversified nuclear and space sectors are foundational to a successful space nuclear enterprise. Technological innovation is the basis for long-term competitiveness and the U.S. industry model can take advantage of private-sector innovation and low-cost delivery. A 2020 U.S. government report on the space industrial base found that public-private partnerships and concerted government efforts were needed to maintain competitiveness.[65] Among other recommendations, the report identified space nuclear power systems as key areas of technological competition. Notably, it considered a launch of the first space reactor since the Cold War as an expected key inflection point in great power competition. 

In recent years, the federal government took several major actions to catalyze development of space nuclear power for security, civil, and commercial purposes. In August 2019, the Trump administration issued the “Presidential Memorandum on Launch of Spacecraft Containing Space Nuclear Systems.”[66] Responding to previous limitations and uncertainties in space nuclear launch authorities, the new pathway established a three-tier system to guide launch approvals based on safety risk analysis. Critically, the memorandum created a pathway for commercial space nuclear power systems for the first time. However, the memorandum has the status of an executive order; future legislation governing launches can further decrease technological development risks for commercial providers. Further, while the new process streamlines interagency processes, it is unclear how the process will integrate in practice with current processes at regulatory agencies.

Beyond the launch memorandum, two major executive orders formalized recent technology progress and built the policy foundation for successful development of space nuclear power for national objectives. Space Policy Directive-6 (SPD-6) established a “National Strategy for Space Nuclear Power and Propulsion,” that would leverage space nuclear systems to “achieve the scientific, exploration, national security, and commercial objectives” of the country.[67] Key goals included developing a fuel supply chain serving both terrestrial and space needs, demonstrating a fission reactor on the lunar surface, and continued improvements in RPS technologies. Critically, SPD-6 discouraged the use of HEU for space reactors in all but the most limited of applications. The directive also provided for interagency collaboration and coordination in development of space nuclear systems, identifying the roles of different agencies in the overall national strategy. A central aspect of the policy was a focus on leveraging private sector. 

Shortly after SPD-6, the Trump administration issued Executive Order (E.O) 13972, which similarly formalized recent developments and established new goals for using advanced reactors for national security and space exploration purposes.[68] In its goal’s statement, the E.O. highlights the importance of the domestic nuclear industrial base to any space activities. Beyond formalizing ongoing activities, specific provisions of the E.O. include directing the National Aeronautics and Space Administration (NASA) to fully evaluate the role of nuclear energy systems in civil space exploration, promoted the development of domestic HALEU supply, and further reiterated the need to integrate multi-agency and private sector technology development efforts through a “Common Technology Roadmap.”

Beyond these executive orders, other federal government activities established a foundation for future technology development. Space nuclear power and propulsion received a call out as a priority area in the National Space Policy in late 2020.[69] Also in late 2020, NASA and DOE signed a general memorandum on collaboration to support space technology development.[70] For space nuclear, DOE plays a central role in funding innovators, performing basic research, and commercializing technologies. The Department is also responsible for fuel production: a new production line dedicated to Plutonium-238 can support several deep space probes per decade, enabling advanced civil space exploration missions.[71]Due to DOE’s importance, the DOE joined the National Space Council in early 2020. Continued coordination between NASA, DOD, and DOE is needed to drive multiple space nuclear pathways, enable commercialization, and share lessons learned.

The Biden administration has an opportunity to continue to develop policy and expand technology plans. In evaluating the role of space nuclear power, the Biden administration can recognize the role of such technologies in enabling scientific exploration and building soft power. Further, successful space reactor projects will augment domestic nuclear fuel demand and material supply chains, accelerating the pace of terrestrial reactor innovation and supporting the administration’s climate policy goals. Congress and the Biden administration can build upon recent success by ensuring continued funding and policy progress for space reactors. Achieving successful demonstration projects for civil, commercial, and military applications is the top near-term priority for space nuclear development. Beyond funding current plans for DRACO, NASA’s lunar surface fission project, and NASA’s NTP project, several policy arenas can increase the chances of success.

Federal agencies and commercial developers must successfully navigate environmental regulations. Testing space nuclear power systems is a big challenge due to radiological safety concerns and any project must meet environmental, DOE, Nuclear Regulatory Commission, and other requirements.[72] Environmental permitting, particularly the National Environmental Policy Act (NEPA), will shape space nuclear research and development, testing, and launches. Currently, NASA is conducting a programmatic environmental assessment (EA) for RHUs, easing the launch approval process for some civil spacecraft. NASA and DOD should consider expanding this EA approach toward space reactors and nuclear rockets, including consideration of a generic environmental impact statement process. The Federal Aviation Administration should also consider what NEPA requirements are needed for commercial licensees.

Defense applications also require successful program administration. If the DOD and USSF pursue space nuclear technologies, they will need to establish transparent procurement, training and, regulatory regimes. For the nuclear navy, these functions are handled by the Office of Naval Reactors. Beyond this office, there is limited expertise and systems for nuclear power system procurement and regulation in DOD. Although the Office of Naval Reactors provides a potential model for a Space Reactors office, the relatively limited number of space reactors needed in the near-term will likely not require a similar bureaucracy. As most proposed space reactors are likely to use automated operation, training needs may not be as great. Commercial vendors could offer an alternative regulatory pathway.

Conclusion: the role of space nuclear energy in strategic competition among great powers

Space nuclear is an enabling technology for civil and military spacepower. Radioisotope power, nuclear reactors, and nuclear rockets can all provide energy and propulsion services that are otherwise not available in outer space or on celestial bodies. The activities enabled by such services are a source of national prestige and enhance scientific knowledge through exploration. Although they have yet to commence, the economic potential of commercial space activities using nuclear technologies could expand the role of the space sector in the global economy. Space reactors may be the best options for space mining, unlocking in-space refueling and reducing space transportation costs. 

National policy and spacepower theory should more fully consider the strategic drivers of space reactor development and steps needed to unleash their potential to enable U.S. power. Improved understanding of Russia and Chinese space nuclear plans is needed, as is analysis of their role within each nation’s space strategy. Radioisotope power sources are essential to scientific and civil space activities yet achieving soft power with them requires continued production of Pu-238. Fission reactors can be most transformational for commercial activities, building economic power through space mining and production of in-space propellant. Nuclear rockets can build spacepower through civil Mars exploration and through performance advantages for military operations in cislunar space. 

If long-term spacepower is dependent on space nuclear technologies, strong industrial policy and sufficient DOD management are needed to ensure American competitiveness. Using space nuclear energy to build spacepower will require competitive and robust domestic nuclear and space industries. Commercial innovations in advanced reactors and fuels provide the foundation for space reactor and nuclear rocket designs, and are needed to keep technology pathways open. In particular, terrestrial demand for HALEU and TRISO fuels can provide a ready fuel source for likely space nuclear systems, and domestic supply chains are needed. To quickly achieve their potential for DOD, space nuclear activities need to move beyond DARPA and other research labs into practical deployments with the U.S. Space Force and potentially other branches. Space nuclear technologies will not be competitive and sustainable unless civil, commercial, and defense applications are pursued in concert, enabling innovation ecosystems and lowering overall costs.

Alex Gilbert is a project manager at the Nuclear Innovation Alliance and a fellow at the Payne Institute at the Colorado School of Mines. This paper represents solely the author’s views and do not necessarily represent the official policy or position of any Department or Agency of the U.S. Government. If you have a different perspective, we’d like to hear from you

NOTES

[1] IAEA. “The Role of Nuclear Power and Nuclear Propulsion in the Peaceful Exploration of Space.” International Atomic Energy Agency, 2005. https://www-pub.iaea.org/MTCD/publications/PDF/Pub1197_web.pdf.

[2] Ibid.

[3] Ibid.

[4] Hayhurst, Marc, Robert Bitten, Eric Mahr, and Vincent Bilardo, Jr. “Space Power Heritage Study Final Results.” NASA, February 2019.

[5] Lange, Robert, and Wade Carroll. “Review of Recent Advances of Radioisotope Power Systems.” Energy Conversion and Management 49, no. 3 (March 1, 2008): 393–401. https://doi.org/10.1016/j.enconman.2007.10.028.

[6] Ibid.

[7] IAEA, “The Role of Nuclear Power and Nuclear Propulsion in the Peaceful Exploration of Space.”

[8] Cassady, R. Joseph, Robert H. Frisbee, James H. Gilland, Michael G. Houts, Michael R. LaPointe, Colleen M. Maresse-Reading, Steven R. Oleson, James E. Polk, Derrek Russell, and Anita Sengupta. “Recent Advances in Nuclear Powered Electric Propulsion for Space Exploration.” Energy Conversion and Management 49, no. 3 (March 2008): 412–35. https://doi.org/10.1016/j.enconman.2007.10.015.

[9] Graham, Cassandra. “The History of Nuclear Thermal Rocket Development.” In Encyclopedia of Nuclear Energy, 290–302. Elsevier, 2021. https://doi.org/10.1016/B978-0-12-819725-7.00059-3.

[10] Skelly, Clare. “Nuclear Propulsion Could Help Get Humans to Mars Faster.” Text. NASA, February 4, 2021. http://www.nasa.gov/directorates/spacetech/nuclear-propulsion-could-help-get-humans-to-mars-faster.

[11] Kammash, Terry. “Fission or Fusion for Mars Missions.” Acta Astronautica 34 (October 1994): 17–23. https://doi.org/10.1016/0094-5765(94)90238-0.

[12] Camp, Allen, Elan Borenstein, Patrick McClure, Paul VanDamme, Susan Voss, and Andy Klein. “Fission Reactor Inadvertent Reentry: A Report to the Nuclear Power & Propulsion Technical Discipline Team,” August 1, 2019. https://ntrs.nasa.gov/citations/20190030875.

[13] IAEA, “The Role of Nuclear Power and Nuclear Propulsion in the Peaceful Exploration of Space.”

[14] Weeden, Brian. “2009 Iridium-Cosmos Collision Fact Sheet.” Secure World Foundation, November 2010. https://swfound.org/media/6575/swf_iridium_cosmos_collision_fact_sheet_updated_2012.pdf.

[15] Sekiguchi, Yukari, and Suzanne Claeys. “Preventing Nuclear Risks in Outer Space.” Nuclear Network, Center for Strategic & International Studies, July 28, 2020. https://nuclearnetwork.csis.org/preventing-nuclear-risks-in-outer-space/.

[16] Voss, Susan S. “Nuclear Security Considerations for Space Nuclear Power: A Review of Past Programs with Recommendations for Future Criteria.” Nuclear Technology 206, no. 8 (August 2, 2020): 1097–1108. https://doi.org/10.1080/00295450.2019.1706378.

[17] U. S. Government Accountability Office. “Nuclear Nonproliferation: DOE Needs to Take Action to Further Reduce the Use of Weapons-Usable Uranium in Civilian Research Reactors,” July 2004. https://www.gao.gov/products/gao-04-807.

[18] Lal, Bhavya, and Jericho Locke. “Trade Offs Between High and Low Enriched Uranium Fueled Space Nuclear Power and Propulsion Systems.” Nuclear and Emerging Technologies for Space, 2020.

[19] Joyner II, C. Russell, Michael Eades, James Horton, Tyler Jennings, Timothy Kokan, Daniel Levack, Brian Muzek, and Christopher Reynolds. “LEU NTP Engine Systems Trades and Mission Options.” Nuclear and Emerging Technologies for Space, 2019.

[20] Powis, Andrew, and Frank von Hoppel. “How Will a NASA Decision on Low vs High Enriched Uranium for a Nuclear Fission Space Power Reactor Effect the Commerical Sector?” Nuclear and Emerging Technologies for Space, 2020.

[21] National Academies of Sciences, Engineering. Space Nuclear Propulsion for Human Mars Exploration, 2021. https://doi.org/10.17226/25977.

[22] Spires, David. “Beyond Horizons: A Half Century of Air Force Space Leadership.” Air Force Space Command, 1998.

[23] Butcher, Lincoln, Jericho Locke, and Bhavya Lal. “Regulations on Ground Testing of Space Nuclear Systems.” Nuclear and Emerging Technologies for Space, 2020.

[24] Idaho National Laboratory. “Atomic Power in Space II,” September 2015.

[25] Aftergood, Steven. “Background on Space Nuclear Power.” Science & Global Security 1 (1989): 93–107.

[27] Aftergood, Steven. “Towards a Ban on Nuclear Power in Earth Orbit.” Space Policy 5, no. 1 (February 1989): 25–40. https://doi.org/10.1016/0265-9646(89)90026-X.

[28] Bennett, Gary L. “Mission Interplanetary: Using Radioisotope Power to Explore the Solar System.” Energy Conversion and Management 49, no. 3 (March 2008): 382–92. https://doi.org/10.1016/j.enconman.2007.06.051.)

[29] Lorenz, Ralph D., and Eric S. Clarke. “Influence of the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) on the Local Atmospheric Environment.” Planetary and Space Science 193 (November 2020): 105075. https://doi.org/10.1016/j.pss.2020.105075.

[30] U.S. Government Accountability Office. “Space Exploration: DOE Could Improve Planning and Communication Related to Plutonium-238 and Radioisotope Power Systems Production Challenges.” Accessed June 29, 2021. https://www.gao.gov/products/gao-17-673.

[31] McClure, Patrick R., David I. Poston, Marc A. Gibson, Lee S. Mason, and R. Chris Robinson. “Kilopower Project: The KRUSTY Fission Power Experiment and Potential Missions.” Nuclear Technology 206, no. sup1 (June 5, 2020): S1–12. https://doi.org/10.1080/00295450.2020.1722554.

[32] Foust, Jeff. “NASA to Seek Proposals for Lunar Nuclear Power System.” SpaceNews, September 2, 2020. https://spacenews.com/nasa-to-seek-proposals-for-lunar-nuclear-power-system/.

[33] Locke, Jericho, and Bhavya Lal. “Emergence of a Commercial Space Nuclear Enterprise.” Nuclear and Emerging Technologies for Space, 2019.

[34] Hardin, L. A. “United States Nuclear Rocket Company (USNRC).” Nuclear and Emerging Technologies for Space, 2014. https://ntrs.nasa.gov/citations/20140008782.

[35] Hubbard, Moderator: Scott, Participants: Ken Davidian, Steve Isakowitz, John Logsdon, James R. (Russ) McMurry, George Nield, and Marcia S. Smith. “Growing the Future of Commercial Space.” New Space 1, no. 1 (March 2013): 3–9. https://doi.org/10.1089/space.2013.1501.

[36] Kornuta, David, Angel Abbud-Madrid, Jared Atkinson, Jonathan Barr, Gary Barnhard, Dallas Bienhoff, Brad Blair, et al. “Commercial Lunar Propellant Architecture: A Collaborative Study of Lunar Propellant Production.” REACH 13 (March 2019): 100026. https://doi.org/10.1016/j.reach.2019.100026.

[37] General Atomics. “General Atomics Delivers Nuclear Thermal Propulsion Concept to NASA,” September 2020. https://www.ga.com/general-atomics-delivers-nuclear-thermal-propulsion-concept-to-nasa.

[38] Greiner, Nathan. “Demonstration Rocket for Agile Cislunar Operations (DRACO).” Defense Advanced Research Projects Agency. Accessed June 29, 2021. https://www.darpa.mil/program/demonstration-rocket-for-agile-cislunar-operations.

[39] RT International. “Russia ‘Tests’ Key Piece of Nuclear Space Engine to Revolutionize Long-Range Missions.” Accessed June 29, 2021. https://www.rt.com/news/442521-nuclear-propulsion-system-russia/.

[40] Hendrickx, Bart. “Ekipazh: Russia’s Top-Secret Nuclear-Powered Satellite.” The Space Review, October 7, 2019. https://www.thespacereview.com/article/3809/1.

[41] World Nuclear News. “China Signs up to Four New Units from Russia,” June 8, 2018. https://www.world-nuclear-news.org/Articles/China-signs-up-to-four-new-units-from-Russia.

[42] Goswami, Namrata. “Waking Up to China’s Space Dream.” The Diplomat, October 15, 2018. https://thediplomat.com/2018/10/waking-up-to-chinas-space-dream/.

[43] Xinhua. “China to Achieve ‘Major Breakthrough’ in Nuclear-Powered Space Shuttle around 2040: Report - Xinhua | English.News.Cn.” Accessed June 29, 2021. http://www.xinhuanet.com/english/2017-11/16/c_136757737.htm.

[44] Goswami, Namrata. “China in Space: Ambitions and Possible Conflict.” Strategic Studies Quarterly 12, no. 1 (2018): 74–97.

[45] A partial sample of these theories include: Gray, Colin S. “The Influence of Space Power upon History.” Comparative Strategy 15, no. 4 (October 1996): 293–308. https://doi.org/10.1080/01495939608403082; Shaw, John. “The Influence of Space Power upon History 1944-1998.” Air Power History 46, no. 4 (1999): 20–29; Dolman, Everett C. Astropolitik: Classical Geopolitics in the Space Age. Cass Series--Strategy and History. London ; Portland, OR: Frank Cass, 2002; Smith, M.V. “Ten Propositions Regarding Spacepower.” Air University Library, October 2002; Hays, Peter L., and Charles D. Lutes. “Towards a Theory of Spacepower.” Space Policy 23, no. 4 (November 2007): 206–9. https://doi.org/10.1016/j.spacepol.2007.09.003; Hertzfeld, Henry R. “Globalization, Commercial Space and Spacepower in the USA.” Space Policy 23, no. 4 (November 2007): 210–20. https://doi.org/10.1016/j.spacepol.2007.09.004; Burris, Matthew. “Astroimpolitic: Organizing Outer Space by the Sword.” Strategic Studies Quarterly 7, no. 3 (2013): 108–29; Klein, John J and Routledge. Space Warfare: Strategy, Principles and Polity. London; New York: Routledge, Taylor & Francis Group, 2014; Developing National Power in Space: A Theoretical Model. Jefferson, North Carolina: McFarland & Company, Inc., Publishers, 2015; Townsend, Brad. “Strategic Choice and the Orbital Security Dilemma.” Strategic Studies Quarterly, Spring 2020, 64–90; and Ziarnick, Brent. “A Practical Guide for Spacepower Strategy.” Space Force Journal, no. 1 (January 31, 2021). https://spaceforcejournal.org/a-practical-guide-for-spacepower-strategy/.

[46] Ziarnick, Developing National Power in Space.

[47] See Ziarnick, “A Practical Guide for Spacepower Strategy;” and Townsend, “Strategic Choice and the Orbital Security Dilemma.”

[48] Garretson, Peter. “What War in Space Might Look Like Circa 2030-2040?” Nonproliferation Policy Education Center, August 13, 2020.

[49] Rumbaugh, Russell. “What Place for Space: Competing Schools of Operational Thought in Space.” The Aerospace Corporation, July 2019.

[50] https://aerospace.csis.org/wp-content/uploads/2019/09/Future-of-Space-2060-v2-5-Sep.pdf ; https://www.dni.gov/files/ODNI/documents/assessments/GlobalTrends_2040.pdf

[51] Shabbir, Zaeem, Ali Sarosh, and Sheikh Imran Nasir. “Nascent Space Powers: Some Policy Issues.” In 2019 Sixth International Conference on Aerospace Science and Engineering (ICASE), 1–5. Islamabad, Pakistan: IEEE, 2019. https://doi.org/10.1109/ICASE48783.2019.9059125.

[52] Defense Intelligence Agency. “Challenges to Security in Space.” Defense Intelligence Agency, February 2019. https://media.defense.gov/2019/Feb/11/2002088710/-1/-1/1/SPACE-SECURITY-CHALLENGES.PDF.

[53] Harrison, Todd, Kaitlyn Johnson, Thomas Roberts, Madison Bergethon, and Alexandra Coultrup. “Space Threat Assessment 2019.” Center for Strategic & International Studies, April 2019; Weeden, Brian, and Victoria Samson. “Global Counterspace Capabilities: An Open Source Assessment.” Secure World Foundation, April 2019.

[54] Gilbert, Alex, Morgan Bazilian, and Julia Nesheiwat. “The Complex Policy Questions Raised by Nuclear Energy’s Role in the Future of Warfare.” Just Security, March 16, 2020. https://www.justsecurity.org/69056/the-complex-policy-questions-raised-by-nuclear-energys-role-in-the-future-of-warfare/.

[55] Baird, Henry D., Steven D. Acenbrak, William J. Harding, Mark J. Hellstern, and Bruce M. Juselis. “Spacelift 2025 The Supporting Pillar for Space Superiority.” Air Command and Staff College, August 1, 1996. https://apps.dtic.mil/sti/citations/ADA392963.

[56] Downey, James, Anthony Forestier, and David Miller. “Flying Reactors: The Political Feasibility of Nuclear Power in Space.” Air University, April 2005.

[57] Ziarnick, Brent. Developing National Power in Space: A Theoretical Model. Jefferson, North Carolina: McFarland & Company, Inc., Publishers, 2015.

[58] Garretson, Peter. “Why the next Space Policy Directive Needs to Be to the Secretary of Energy.” The Space Review, July 1, 2019. https://www.thespacereview.com/article/3744/1.

[59] Sabathier, Vincent, and G. Ryan Faith. “Smart Power Through Space.” Center for Strategic & International Studies, 2008; Dinerman, Taylor. “NASA and Soft Power, Again.” The Space Review, June 15, 2009. https://www.thespacereview.com/article/1396/1.

[60] The White House National Space Council. “A New Era for Deep Space Exploration and Development.” The White House National Space Council, July 23, 2020.

[61] Sadat, Mir. “America Must Build Its Technology Industries to Win against China and Russia.” TheHill, October 18, 2020. https://thehill.com/opinion/technology/521088-america-must-build-its-technology-industries-to-win-against-china-and.

[62] Voegeli, Nathan. “Space Nuclear Reactors: History and Emerging Policy Issues.” The Nonproliferation Review 14, no. 1 (March 2007): 163–75. https://doi.org/10.1080/10736700601178648.

[63] GAIN. “Advanced Nuclear Directory: Developers, Suppliers and National Laboratories.” Gateway for Accelerated Innovation in Nuclear, January 2021; Gilbert, Alexander Q., and Morgan D. Bazilian. “Can Distributed Nuclear Power Address Energy Resilience and Energy Poverty?” Joule 4, no. 9 (September 2020): 1839–43. https://doi.org/10.1016/j.joule.2020.08.005.

[64] Lal, Bhavya, and Jericho Locke. “Trade Offs Between High and Low Enriched Uranium Fueled Space Nuclear Power and Propulsion Systems.” Nuclear and Emerging Technologies for Space, 2020.

[65] Ichord, Jr., Robert, and Bart Oosterveld. “The Value of the US Nuclear Power Complex to US National Security.” Atlantic Council, October 2019.

[66] Butow, Steven, Thomas Cooley, Eric Felt, and Joel Mozer. “State of the Space Industrial Base 2020.” 2020 State of the Space Industrial Base Workshop, July 2020.

[67] Trump Administration. “Presidential Memorandum on Launch of Spacecraft Containing Space Nuclear Systems,” August 20, 2019.

[68] Trump Administration. “Presidential Policy Directive 6 (Space Policy), ‘National Strategy for Space Nuclear Power and Propulsion,’” December 23, 2020. 

[69] Trump Administration. “Executive Order 13972. Promoting Small Modular Reactors for National Defense and Space Exploration,” January 14, 2021.

[70] Trump Administration. “National Space Policy of the United States of America,” December 9, 2020.

[71] “Memorandum of Understanding between Nationonal Aeronautics and Space Administration and U.S. Department of Energy Regarding Energy-Related Civil Space Activities,” October 2020.

[72] U. S. Government Accountability Office, “Space Exploration.”

[73] Butcher, Lincoln, Jericho Locke, and Bhavya Lal. “Regulations on Ground Testing of Space Nuclear Systems.” Nuclear and Emerging Technologies for Space, 2020.