[1][2] The project started in October 2015, led by NASA and the DoE’s National Nuclear Security Administration (NNSA).

[3] As of 2017, the Kilopower reactors were intended to come in four sizes, able to produce from one to ten kilowatts of electrical power (1–10 kWe) continuously for twelve to fifteen years.

During those missions, the reactor would provide power for the machinery necessary to separate and cryogenically store oxygen from the Martian atmosphere for ascent vehicle propellants.

Once the reactor reaches its destination, the neutron absorbing boron rod is removed to allow the nuclear chain reaction to start.

However, the depth of control rod insertion provides a mechanism to adjust the rate of the uranium fission, allowing the heat output to match the load.

[15] The goal of the test reactor is to closely match the operational parameters that would be required in NASA deep space missions.

[16] The first tests used a depleted uranium core manufactured by Y-12 National Security Complex in Oak Ridge, Tennessee.

[1] The prototype Kilopower uses a solid, cast uranium-235 reactor core, about the size of a paper towel roll.

The tests included thermal, materials, and component validation, and culminated in a successful fission trial at full-power.

The test evaluated failure scenarios including shutting down the Stirling engines, adjusting the control rod, thermal cycling, and disabling the heat-removal system.