NASA Is Testing A Space Nuclear Reactor | Kilopower Project

The Kilopower project is not new; In October 2015, NASA started this project for nuclear reactor for space. As of September 2017, a test reactor has been built. The 6.5 feet tall reactor can generate up to 1 kilowatt of electric power.

NASA has completed the development phase and now they will be testing the reactor that could literally empower astronauts on the Red planet’s surface. Not only this, it can even energize habitats and run equipment to transform Mars resources into oxygen, water as well as fuel.

The testing is already started in November 2017 and it will go through early 2018. NASA is partnering with the Nevada National Security Site of US Department of Energy to appraise fission power technology. Let’s dig deeper into the Kilopower project.

Overall Objective and Elements

The aim is to develop a compact, scalable, low cost fission power system for future space missions. The prototype Kilopower includes Uranium-235 reactor core, passive sodium heat pipes for transferring heat, and flight-ready stirling engines for converting heat to electricity.

1kW Kilopower nuclear reactor prototype | Image credit: NASA

It is supposed to provide modular option for Human Exploration and Operations Mission Directorate (HEOMD) Mars surface mission, enable Science Mission Directorate (SMD) survey missions, reduce NASA’s dependency on Pu238, and bridge the gap between Radioisotope Power Systems (RPS) and 40 kW class fission power technology.

Why Kilopower?

The Kilopower tech demonstration is both practical and affordable step towards getting a reactor power system in space. Its small hardware size (about the size of a paper towel roll) and low power level enable usage of current facilities within present regulatory authority.

The core of the reactor can be fabricated and shipped with current assets, and the same modules used to test prototypes could be transferred to the DOE facility and used in the nuclear test.

It can provide a high energy density power source and can operate independent of solar energy, in extreme harsh environments, like Mars surface. The technology that NASA is testing can be used in several space missions, and might be the first step for fission reactors to build a new paradigm of inspiring space research.

Solar-Independent Power

Over the past 50 years, NASA has flown several missions powered by RTGs (Radioisotope Thermoelectric Generators), like the Curiosity rover, two Viking Mars landers, Apollo, New Horizons, two Voyager spacecraft and Cassini mission. RTGs generate electric power passively without any moving parts, utilizing heat from the natural decay of their radioisotope heat source.

The Kilopower project, on the other hand, is a small approach for long lasting solar-independent electric power for extraterrestrial surfaces and space. It can generate an electric power ranging from 1 to 10 kilowatts (enough to power anything from 1 toaster to entire household), continuously for around 10 years.

Design And Testing

The prototype will be tested in the Nevada desert at the Nevada National Security Site. Before the reactor is switched on (before starting fission) the fuel of the reactor is very safe – very less radioactive. The fissioning reactors deliver heat to the stirling converters, each converter producing around 100 watts. The hardware will undergo a full power test for approximately 28 hours.

The primary aim of the test is to confirm the predicted performance of the overall system and move it to a Technology Readiness Level (TRL) of 5. It’s a breadboard test carried out in a vacuum environment, running the components in the space-like conditions.

The reactor core is a cylinder of six inch diameter filled with Uranium. This Uranium core is surrounded by a beryllium oxide (BeO) reflector, and a single rod of boron carbide (B4C) is used to turn on the reactor.

Reference: NASA’s Kilopower reactor development 

The reactor is based on well established nuclear physics to self regulate the fission reactions. This fact eliminates the requirement of complicated control system. As mentioned above, the reactor uses nuclear fission to generate heat, which is transferred to stirling converters through heat pipes. These converters then turn the heat into electrical energy. A radiator is used to keep the stirling converters cool. 

Thermal prototype testing with sodium heat pipes radiating at over 800C


Having a nuclear powered system for Mars explorers would be a game changer – we don’t have to worry about power requirements during the night time or sunlight reducing dust storms. It could provide a constant power supply regardless of your location on Mars. Also, it could expand the possible landing sites to include the high northern latitudes of Mars. The technology would be ideal for lunar exploration objectives too.

Read: NASA Will Use Disruption Tolerant Networking For Space Communications

The project is named Kilopower because it offers a kilowatt for near-future space mission, which were previously constrained to use less. For now, it can provide kilowatts, but in future it could be evolved to generate hundreds of kilowatts, or even megawatts of power.

Update (May 2018): Nasa successfully demonstrated the Kilopower Reactor using Stirling Technology.

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