It is hard to imagine a future in space without fission reactors. Almost every complex activity beyond low Earth orbit (LEO) will require more power than solar can reasonably produce, and much of what we now do in space is unnecessarily constrained and over-complicated by not having enough power. The robotic probes we send into deep space today are underpowered, prohibiting them from using modern cameras and other scientific instruments, and limiting their transmission bandwidth back to Earth at the cost of reduced science data. There istalk of building commercial space stations in LEO, however, a station with 100 or more residents would require preposterously large solar panels, significantly increasing the overall cost and number of launches
By contrast, a nuclear fission reactor could be placed in orbit with a single launch. With new advances in reactor technology, fission reactors can now generate massive amounts of power in a relatively small package, all with increased safety and simplicity in operations. More power will remove constraints from mission design, enabling cheaper and more-effective space exploration and will pave the way for lower-risk human habitation. Many private companies are seeking to launch fission reactors for their missions. This may have been an unthinkable proposition 20 years ago, but so were the private launch and satellite industries, both of which are now flourishing. In response, a recent Presidential memo revamped the launch approval process for government agencies, and for the first time, defined it for commercial actors. Is the public ready for this future?
Advances in nuclear fission
The design of most fission reactors the ground dates back to the 1960s and 70s. However, new designs being tested that are safer, smaller, and cheaper. Oklo, a California-based company with investment from DCVC, has been engaged in pre-application activities with the US Nuclear Regulatory Commission since 2016 for the Aurora design, and is preparing to submit its first license application. The reactor is self-regulating—the fission reaction slows or stops as core temperature increases. It can also consume waste from older, lower energy reactors - nasty stuff with a half-life of millions of years - reducing this waste to byproducts with only a 300 year half-life, generating power along the way. 300 years is a manageable waste problem on a human scale; we can store cognac for that long, but we have no real understanding of how to store something safely for millions of years. This alone is sufficient reason to start building these reactors in large quantities. The fuel is not weapons-grade, so there is no proliferation risk, and in Oklo’s case, Aurora fits on less than half of an acre. The design is modular and can be easily scaled up and down. In its smaller incarnation, the reactor could power a small satellite for years, and at the high end, an entire lunar colony from a single reactor.
USNC, a Seattle-based company, has been making similar progress with the Canadian regulators, seeking approval to build their Small Modular Reactor. Like Oklo, their reactor is dual-use. They can power small towns and cities at significantly lower costs than older reactor designs, and by the same virtues, the reactor is ideal for powering a small space station or base on the Moon.
In 2018 NASA’s Kilopower project achieved promising results with Krusty, a reactor designed for planetary surface use. Krusty is currently capable of producing ~1 kW, self-regulates through thermal expansion, and is designed to be safely operated within a reasonable distance from inhabitants. Kilopower uses Highly- Enriched Uranium (HEU), which is a weapons-grade, though, at launch, the radiological hazard would be limited to the naturally occurring radioactivity present in the uranium reactor core (<5 Curies).