The top priorities for the commercial space industry and space agencies for the next 20 years are obvious. For the first time since the Apollo era, astronauts will be deployed to the Moon first, and then permanent infrastructure will be built so they may stay there for extended periods of time. The first crewed trips to Mars will then be launched, followed by follow-up missions every 26 months, which will result in the development of surface habitats (and maybe a permanent base). Space organizations are looking into next-generation propulsion, power, and life support technologies to achieve these goals.
This includes solar-electric propulsion (SEP), which uses sun energy to drive Hall-Effect thrusters with exceptionally high fuel efficiency. They are also investigating tiny nuclear reactors and nuclear thermal propulsion (NTP), which would enable faster travel times and a consistent power source for habitats on the Moon and Mars. Along with Rolls-Royce, the UK Space Agency (UKSA) has collaborated with NASA to create nuclear technologies for space exploration. The international car and aerospace company recently teased the appearance of their “micro-reactor” in a tweet.
Long-distance space exploration has relied on thermoelectric generators for years. The Viking 1 and 2 orbiters and landers, which were the first to study Mars’ surface, were among the first missions to rely on them. The thermoelectric reactors were also used by the Voyager 1 and 2 spacecraft, which are now in interstellar space and have been running for more than 45 years. Missions like the Curiosity and Perseverance rovers, as well as the New Horizons probe, have been made possible in recent years because to multi-mission radioisotope thermoelectric generators (MMRTG).
Researchers are thinking about nuclear technologies that have been thoroughly tested since the early space era, including the Nuclear Engine for Rocket Vehicle Application, as they ponder the future of space and the exploration aspirations of NASA, the ESA, China, and others (NERVA). Programs like NASA’s Kilopower Reactor Using Stirling Technology (KRUSTY) and the NASA/DARP project to build a spacecraft that would use nuclear-thermal propulsion are the results of more recent efforts (NTP). In order to keep up, the UKSA (a crucial component of the ESA) has teamed up with Britain’s top aerospace developer.
In December 2021, Rolls-Royce revealed that they have partnered with the UKSA to investigate nuclear power alternatives for the next space missions. For lengthy trips far from Earth, when solar power is not always an option, the resulting technology will offer propulsion and power systems. This includes the South Pole-Aitken Basin, where surface habitats are planned to be constructed in the near future by NASA, the ESA, China, and Russia. This area experiences a single “lunar night” that lasts for fourteen days before giving way to another fourteen days of nonstop sunlight.
The distance between Mars and the Sun varies from 1.38 to 1.66 times the distance between Earth and the Sun throughout a Martian year, which lasts around 687 Earth days. Because of this, Mars receives only about half as much radiation as Earth does, and yearly dust storms can cause severe cloud cover that can damage solar panels. Examples include the Opportunity rover, which operated continuously on Mars for 15 years before its mission was terminated in 2018 due to a global dust storm. The InSight lander stopped operating more recently as a result of dust accumulation on its solar panels.
Transit times are a problem when sending crewed missions to Mars. Currently, missions are launched every 26 months by NASA and the China National Space Agency (CNSA) to correspond with Mars and Earth’s closest points in their orbit (aka. a Mars Opposition). These expeditions will need (at least) six months to go to the Red Planet with current technology. The crews will be living in microgravity and being subjected to high quantities of solar and cosmic radiation throughout that time.
To enable nuclear propulsion and surface base power, Rolls-Royce is creating a “micro-reactor” in accordance with the agreement. At the International Astronautical Congress (IAC) gathering in Dubai in October 2021, the idea was announced. According to a news release, the technology would have been used both at home and in space, and it would be able to produce power in the “watts to megawatts” range. They also mentioned that a prototype micro-reactor would be ready in 2029. At the time, Rolls-Director Royce’s of Future Programs, Abi Clayton, said:
“Alongside the micro-reactor technology, we are also providing our nuclear knowledge in the development of Radioisotope Power Systems, and the space opportunities of converting ‘decay heat’ into electrical energy via thermoelectric generators or moving parts. This is a very exciting time for the Future Programmes team and the development of nuclear power across Rolls-Royce.”
The mini-reactor displayed at the IAC 2021 has the same design as the early model displayed in the tweet. A Rolls-Royce Micro-Reactor is planned to employ an inherently safe and incredibly resilient fuel form, the business wrote, adding a few more specifics about how it would function this time. Each uranium particle is enclosed in several shielding layers that serve as a containment system and protect it from harsh environments.
Other teases, such as the several movies and artist renderings posted on the Rolls-Royce Space website, highlight the various uses and functions that they anticipate this technology will have. These include fast-transit nuclear spacecraft that will explore beyond the Earth-Moon system and even beyond Mars, as well as reactors that would power surface habitats on the Moon and Mars (to which they also incorporate resource acquisition and usage). Small satellites, on-orbit assembly, and hypersonic spacecraft are among further potential uses.
Even though there are few specifics about the micro-reactor, it is obvious that the UKSA and Rolls-Royce want to play a significant role in the development of space exploration and space commerce. According to Parliamentary Under Secretary of State for Science, Research, and Innovation Amanda Solloway, MP:
“As we build back better from the pandemic, it is partnerships like this between business, industry and government that will help to create jobs and bring forward pioneering innovations that will advance UK spaceflight. Nuclear power presents transformative possibilities for space exploration and the innovative study we are conducting with Rolls-Royce on this could help to propel our next generation of astronauts into space faster and for longer, significantly increasing our knowledge of the universe.”