Thought Leadership

Karl-Georg Schlesinger
Nuclear in Space: Pros and Cons

Resource Abundance through Nuclear Technology in Space - a technical Solution to a moral Dilemma

by DC Member Karl-Georg Schlesinger


The unmatched capabilities of deploying nuclear technologies in space – particularly for asteroid deflection - may imply a serious moral dilemma. Even for the absolute emergency case of a hazardous object finding itself on a collision course with Earth, i.e., the so-called ”planetary defense” scenario, the underlying decision-making framework is complex and not resolved at all. In that case, applying a nuclear explosive is the most efficient and promising solution, but it also leads to the most delicate situation concerning international treaties.

The upside of a commercial use of nuclear devices in space would be an economic leapfrog potential since ultra-low energy costs would allow for abundant resource supply. However, a nation that decides to pursue this path would have to leave international contracts and put up with violating arms control measures. This culminates in the tradeoff between the prospect of economic prosperity – particularly tempting for emerging nations - and the goal of nuclear non-proliferation.

Approaching the objective from an entirely new perspective, i.e., designing a technology compatible with international contracts and security measures and providing the economic benefits of nuclear fusion energy densities, could solve the moral dilemma. With OuSoCo – standing for Outer Solar System Company – the deep space company in stealth mode I founded two years ago with Melanie Bochmann, we have developed a technology solution for this apparent conundrum.

Keywords: Asteroid deflection, Space Resources, Nuclear Technology, Planetary Defense

1.    The Key Role of Resource Abundance

Maintaining peace and international security – as it is proclaimed in Article 1 of the UN Charter– is the leading purpose and principle of why the UN was established. Eco- nomic growth, affordable and clean energy as well as reduc- ing inequalities are among the 17 goals of the 2030 Agenda for Sustainable Development, adopted by all United Na- tions Member States in 2015.

Ensuring resource abundance and low cost of energy are key drivers to achieving these goals. The EU proposed the Critical Raw Materials Act, given the crucial role of certain raw minerals in unfolding economic opportunities. The list of critical raw materials defined by each of the major geopolitical actors in trade - China, Japan, EU, In- dia, and the US – differs but is derived based on individual strategic goals and economic risk assessment. These ma- terials are considered essential for science and technology advancements, such as decarbonization technologies, na- tional security, and digitization efforts.

At the same time, competition over natural resources can potentially fuel conflicts often obscured by ethical, re- ligious, or political tensions.

2.   Prospects of Asteroid Mining

Mining resources from asteroids could potentially provide a solution to these issues:

ˆ Asteroids offer critical resources in high quality and large scale, while negative social and environmental mining footprints can be avoided in space.

ˆ Due to the small body size (i.e., a large surface area compared to a small radius), practically the whole asteroid is accessible for mining. In contrast, larger bodies, such as Earth or Moon, require deeper mines resulting in higher energy efforts, costs, and risks.

While the DART mission – where an object was deflected using a kinetic impactor from its orbit as a test method for planetary defense – was successful in 2022, and other missions have already returned asteroid probes to Earth for scientific purposes, the commercial efforts of the first generation of space mining companies from a decade ago failed. One reason was that the cost of transporting resources from the asteroid’s original orbit to an accessible orbit in the Earth-Moon system was simply too high to make this a viable option even for precious metals like Platinum group elements. The prevailing approach, which is highly energy-intensive, involves transporting batches of resources using small probes that continuously travel back and forth between the original asteroid orbit and the in- tended destination, often within the Earth-Moon System. The only viable solution is transporting the whole as- teroid body in one piece. This means deflecting an asteroid from its original orbit – i.e., an orbit in Mars proximity or even farther away - into a stable and much closer park- ing orbit in the Earth-Moon system to make its resources accessible. Such a deflection maneuver, e.g., using a nu- clear standoff method as described in the following - still requires vast amounts of energy that can only be provided using a nuclear device (also referred to as cartridge). A standoff nuclear deflection maneuver would require 1) to deliver a nuclear explosive to the proximity of the asteroid of interest. In a next step 2) the nuclear device detonates with some distance from the asteroid, so that nuclear re- action output – usually x-rays and neutrons – 3) deposit energy in the asteroid’s surface material. The energy de- position then 4) leads to high-velocity ablation of asteroid material, which expands outwards and blows off the sur- face. This effect can be compared to a rocket-like exhaust, leading to a change of velocity and an orbital deflection. Due to the nuclear energy densities that such a device fea- tures, it would also allow for compatibility with available payload capabilities of existing launch vehicles. The ex- plosive yield of a nuclear device for a mission intended to deflect an object of 1 to3 kilometers in diameter would re- quire a very large standoff detonation from a device with 1 to 10 gigaton explosive yield, the equivalent of 1 to 10 billion tons of TNT or up to one million Hiroshima bombs. Note also that this is the only existing technology that allows it to reach the needed very low level of cost due to its unmatched nuclear energy densities. In addition, there is a scaling effect: A high-yield device is not much more expensive to produce than a smaller device. Consequently, this leads to a cost level of only a fraction of a cent per kWh, far below anything that can be achieved on Earth.

3.  Legal Framework derived from Planetary Defense

In planetary defense, it is broadly established – also confirmed by recent simulations - that nuclear weapons technology is the only efficient option to deflect a large- scale asteroid (a few kilometers in diameter) away from its collision course with Earth. At the same time, the plane- tary defense scenario presents unresolved legal questions. The two main nuclear arms control treaties – the nuclear test ban treaty and the outer space treaty – forbid the nuclear option for deflecting a hazardous object.

However, proponents of the nuclear option argue that nuclear explosives should be kept in the weapons arsenal– or even be built - to be prepared for a potential asteroid threat. Following that argumentation, very high-yield nu- clear explosives are critically needed for the case of emer- gency, not having any terrestrial justification and entirely contradicting international disarmament efforts and the major nuclear arms treaties.

The crucial point for the case of emergency is that one mustn’t run into a situation where one has to trade the low-probability-high-impact risk of an asteroid threat against the risk of increasing the danger of a nuclear inci- dent between nations. Therefore, simply ignoring international treaties does not seem to be a viable option. The same holds for the possibility that a major nation decides to use a nuclear device in a hypothetical planetary de- fense scenario and condones to leave the contracts (which is legally possible for both contracts). Many authors con- sider the authorization through the UN Security Council in such an asteroid-threat-related scenario as the decision- making framework being most compatible with interna- tional law. Some authors even see it as the only option that ensures a safeguard mechanism (see Green (2019) and the extensive literature cited therein).

Beyond the case of humanity facing an existential cri- sis in the form of a threatening asteroid, legal problems also arise from the need to perform nuclear tests as part of a planetary defense strategy. Under these conditions – where a concrete threat from an asteroid is not yet im- minent – the international community may not be willing to trust a state maintaining its nuclear weapons capabili- ties for testing a feinted asteroid deflection maneuver. Go- ing beyond this and seeking exemptions from international treaties to deflect an asteroid to make its resources acces- sible does not seem possible. Based on the legal discussion mentioned above, this would appear to be impossible to reconcile with Chapter VII of the UN Charter (Chapter et al. (1945)) and the mandate of the Security Council to maintain or restore international peace and security. This situation exposes the international community to a severe risk.

Despite these fundamental security and legal concerns, it is crucial to point out the unique upside potential of nu- clear technology, applied for peaceful, industrial purposes: The specific physics of combining nuclear fusion energy densities and a large cartridge of fusion fuel (as supplied by a nuclear bomb) into a device leads to a reduction of cost per unit of energy by many orders of magnitude compared to any other process (this was already noted by world- famous physicist Freeman Dyson in Dyson (1968) where he calculated the cost per kWh to 0.0003 cent in terms of 1968 dollars, i.e. valued 0.0026 cent in today’s dollars).

4.   Pulsed Propulsion as a Game-changer

In 2022 a detailed study was published on the im- plications of Pulsed Propulsion for international law (see Reynolds and Outten (2022)). Pulsed Propulsion is a tech- nology very close to the standoff nuclear deflection of as- teroids and was pursued in the context of Project Orion in the US during the 1960s. Tests and engineering efforts confirmed the feasibility of the project. The main reason for abandoning Project Orion was that tests became illegal due to the Nuclear Test Ban Treaty of 1963. Speaking very high level: Instead of an asteroid, a spaceship is propelled externally by a nuclear explosion. The two technologies are close enough, so the results of the study by Reynolds and Outten (2022) can be applied to the asteroid deflection case, too. The technology of the company OuSoCo that I co-founded– standing for Outer Solar System Company and operating in stealth mode – uses a similar but safe and legally compatible principle, as it is described below in further detail.

Deploying such a technology would potentially allow an emerging nation to leapfrog its economic development through resource abundance and ultra-low energy costs. Raising the living standard and well-being of billions of people and avoiding looming conflicts over resources would be a tempting perspective for some governments. However, on the downside deploying this technology would imply vi- olations of international law and abandoning strict control over nuclear proliferation. The study warns that emerg- ing economies might see the option to leave international contracts as a prize they might be willing to pay to access this technology.

5.  The Moral and Legal Dilemma of Nuclear Applications in Space

It seems like we are facing a question that no politi- cian and nobody in the world would have ever wanted to be asked: Do we give the prospect of cheap energy and abundant critical resources (which could raise the living standard of billions and avoid looming conflicts over re- sources) the preference over a strict control over nuclear proliferation and clear goals of disarmament or vice versa? But is this true? Do we really have to face this ques- tion? The answer is: No. The physics of nuclear fusion energy densities in a large fusion fuel cartridge cannot be beaten. But the dilemma above arises because nu- clear weapons are presently the only technology to realize this physics. What if there would be a different technol- ogy solution? This would open the possibility of follow- ing a path of energy and resource-driven prosperity. At the same time, it would allow the UN and the Security Council to opt for an even stricter path of nuclear non- proliferation and disarmament in the future since nuclear weapons would no longer be necessary in the stockpil then, even for the extreme case of planetary defense.

6.   A Technology Solution

Historically, the concept of nuclear deflection of an as- teroid was developed much later than nuclear weapons. It is, therefore, based on the idea of applying a nuclear device from the existing stockpile to this application. But sup- pose we would proceed the other way around. What if we start from the problem of asteroid deflection and demand to use nuclear fusion energy densities and a large fusion fuel cartridge (to achieve a low level of cost) starting from a blank sheet of paper for the design of the nuclear device? Of course, we would aim for a non-weapons design to avoid any conflict with international treaties and be fully com- patible with disarmament goals.

This is precisely what we have developed and filed patents for at OuSoCo. The central idea is that the car- tridge, which is placed next to the asteroid with a standoff, does only contain the fusion fuel. It does not contain any driver to start the fusion reaction (like the fission-based ignitor of the hydrogen bomb). In other words, it is a rather simple fuel tank with no mechanism to ignite it- self. The driver is separated from the fuel cartridge over a large distance of at least 2 million kilometers, which is dictated by technical details of the mechanism. It takes the form of a Laser system which accelerates a small sail by the pressure of light, a technology that already has been applied by JAXA and others. The small sail then hits the fusion fuel cartridge at relativistic velocity, lead- ing to an ultra-high kinetic impact energy which is more than enough energy to ignite the fusion reactions. Due to this ultra-high level of impact energy, one of the central challenges of nuclear fusion applications gets solved, i.e., depositing enough energy for igniting nuclear fusion reac- tions. The crucial point for the present discussion is that this significant spatial separation of driver system and fusion fuel implies a clear distinction from any weapons tech- nology, leading to compatibility with international treaties and disarmament goals.

Beyond this, the technology is fully compatible with further regulation of the Laser system. It, therefore, al- lows for the next step in international treaties and future measures to maintain or restore international peace and security.

Due to the unique characteristics of OuSoCo’s tech- nology – featuring ultra-low energy costs and providing abundant, affordable resources – a true space economy with manufacturing and assembly facilities in space fi- nally comes within reach. The scenario drawn by Jeff Be- zos (Doepfner (2018)) of moving heavy industry off Earth and the Earth being zoned residential and light industry, would not be reserved for the great-grandchildren’s great- grandchildren generation, but could already be tangible. Resource abundance would fuel both a flourishing space economy and prosperous development on Earth.


Chapter, V., Chapter, X., Territories, D., Chapter, X., 1945. Charter of the united nations. available at the website http://www.un. org/en/documents/charter/chapter14. shtml (accessed 2 March 2020) .

Doepfner, M., 2018. Jeff bezos reveals what it’s like to build an empire.

Dyson, F.J., 1968. Interstellar transport. Physics Today 21, 41–45.

Green, J.A., 2019. Planetary defense: Near-earth objects, nuclear weapons, and international law. Hastings Int’l & Comp. L. Rev. 42, 1.

Reynolds, G.H., Outten, J.L., 2022. Pulsed nuclear space propulsion and international law: Some preliminary observations. J. Air L. & Com. 87, 445.