Is nuclear technology the next space frontier?

Our generation’s space race is well under way, driven not only by the spirit of exploration, but also the desire to dominate in a new theatre of war
Illustration by Shane Cluskey for The Parliament

By Maximilian Lock

Research scientist at the Institute of Atomic and Subatomic Physics, Vienna

09 Oct 2023

Setting foot on distant planets and building new homes among the stars have long been the realm of science fiction, but both are edging closer to becoming a reality. Nuclear technologies with the potential to propel spacecraft and enable the existence of extraterrestrial bases, have attracted major interest and funding in recent years. If they can be safely implemented, the result would be a step-change in our ability to exist in and travel through space. 

But increasing tensions between world powers and the creeping militarisation of space provide a dangerous background for this nuclear revolution. Our generation’s space race is well under way, driven not only by the spirit of exploration, but also the desire to dominate in a new theatre of war. 

At the heart of almost all nuclear technology is the process of fission, in which an atom splits apart, releasing a huge amount of energy in the form of heat. When a nuclear reactor is brought into a “critical” state, the intense heat from a controlled chain reaction can be used to generate electricity, as in the hundreds of nuclear power plants operating on Earth today.  

A spacecraft or an extraterrestrial base with a small nuclear reactor would have a ready supply of power for life support, heat and any other needs astronauts may have, without being dependent on intense sunlight or a constant supply of fuel from Earth. 

The abundance of energy generated from a small mass of nuclear fuel means the propulsion of spacecraft by nuclear energy could be extremely efficient, halving the travel time to Mars, according to some estimates. This would drastically reduce astronauts’ exposure to the hazardous radiation present in interplanetary space, and the psychological stress of the journey, as well as the resources needed. Nuclear propulsion is also expected to enable far greater manoeuvrability than is currently feasible. 

The European Space Agency’s plans for nuclear propulsion are rather modest

The promise of agility in space turns what may otherwise have been a technology of purely scientific interest into a matter of national defence. As the war in Ukraine has shown, satellites now play a vital role in conventional warfare, and the United States, China, India and Russia have recently all demonstrated anti-satellite weapons. At a press briefing earlier this year, a senior US military official pointedly declared that the country was “ready to fight tonight in space if we have to”. 

The race is on to gain the advantage that nuclear propulsion would provide in such a fight. The Demonstration Rocket for Agile Cislunar Operations (Draco) programme, run by the US Department of Defense in collaboration with Nasa has a $0.5bn (€0.4bn) contract with Lockheed Martin to develop a nuclear-powered spacecraft, to be demonstrated in Earth orbit by 2027.  

Russia’s Nuklon project aims to demonstrate the technology in 2030, while China is believed to be aggressively investing in a wide range of space technologies, including nuclear power and propulsion.  

The drive to dominate cislunar space, or the area between the Earth and the moon, similarly underlies the race to build a permanent lunar base. Nuclear technology is vital to the establishment of a lunar base, making it possible for humans to survive the long and cold lunar night – around 14 days, with a temperature of about -250C in the polar regions.  

In 2017, then- president Donald Trump signed a space policy directive instructing Nasa to lead a programme to establish a presence on the moon. To join this initiative, later named “Artemis”, international partners must sign a series of non-binding bilateral agreements meant to guide civil space exploration and recognise nations’ right to commercial space mining. So far, 29 nations have signed these Artemis Accords, including Europe’s five largest economies, as well as India and Japan. 

China and Russia are absent from this list. Russia has described the agreements as too “US-centric”, while Chinese media has compared them to the British enclosures, a historical movement whereby communal lands were transferred to private hands. Instead, the two nations intend to collaborate on their own base, with construction beginning in 2026. 

Another of former president Trump’s space policy directives included the goal of demonstrating a small modular nuclear reactor on the lunar surface. Small modular reactors (SMRs) are a proposed new generation of nuclear reactors, less powerful than a traditional power plant, but smaller and more versatile – making them perfect for space applications.  

Most designs use high-assay, low-enriched uranium as a fuel, which is currently unavailable at scale, and Trump signed an executive order pushing for the construction of a US-based supply chain shortly before leaving office. China, meanwhile, is on course to have the world’s first commercial SMR operational in 2026.  

Where is Europe in all of this? The European Commission is planning to launch a collaboration scheme later this year to develop operational SMRs by the start of the next decade, with a goal of “EU technological sovereignty”.  

The European Space Agency’s plans for nuclear propulsion, meanwhile, are rather modest, consisting of two small programmes, each tasked with obtaining feasibility studies into different forms of nuclear propulsion. According to an ESA spokesperson, “nuclear propulsion has never been demonstrated in Europe, this is why we have to start with preliminary investigation”. 

It is natural to wonder how safe this proliferation of nuclear fission technology will be, given the tendency for rocket launches to fail explosively, and for orbiting bodies to occasionally undergo uncontrolled re-entry into the Earth’s atmosphere. Proponents of nuclear technology claim these problems can be solved by keeping the nuclear fuel in a non-critical state until the craft is safely away from Earth, and by only activating the reactor far away from Earth’s atmosphere.  

Space science is a humbling enterprise, filled as it is with countless reminders of human smallness. Paradoxically, each advance is an expression of the astonishing power of human ingenuity and organisation. As nuclear technology brings us into a new frontier of possibilities, and potential conflicts, we must remember these twin lessons. The decision to deploy it must be made carefully – out of hope for the future of humanity, not from our fear of each other.