The DoD plans to launch two nuke-propelled spacecraft by 2027

The United States Department of Defence's (DoD) Defence Innovation Unit (DIU) has recently announced its intention to develop the next generation of nuclear propulsion for spacecraft. In a recent press release, the DIU has awarded two Prototype Other Transaction (OT) contracts to two companies to develop prototype spacecraft to launch them in 2027 potentially.

The DIU, if you have never heard of them before, is an organization specially tasked with helping the DoD leverage commercial technology and dual-use technology to solve operational challenges at speed and scale.

The two companies, Seattle-based Ultra Safe Nuclear Corporation, and Avalanche Energy Designs, will be working together to develop the DUI's planned Nuclear Advanced Propulsion and Power program. Under the agreement, these commercial enterprises will be tasked with building the necessary propulsion components for small spacecraft that allow them to maneuver at will.

“Advanced nuclear technologies will provide the speed, power, and responsiveness to maintain an operational advantage in space,” said Air Force Maj. Ryan Weed, DIU’s program manager for NAPP and the commercial market for nuclear propulsion technology.

“Nuclear tech has traditionally been government-developed and operated, but we have discovered a thriving ecosystem of commercial companies, including start-ups, innovating in space nuclear,” he added.

How does nuclear propulsion work in space?

Nuclear propulsion might be the way to go when it comes to moving around at will in space. This is because, among other reasons, nuclear propulsion systems have a high thrust-to-weight ratio and are more efficient in operation.

This makes it easier to perform rapid maneuvers in space than with electric or chemical systems, which is clearly very desirable. 

"Future missions will demand more maneuverability and electrical power to expand the capabilities of spacecraft, allowing for orbital changes, methods to control or facilitate de-orbiting, the transfer of materials between orbits, and solar shadow operations, to name a few, etc." explained the DUI. 

To help with this ambition, Ultra Safe Nuclear’s design is based on its chargeable battery called EmberCore, which it will demonstrate for space-based propulsion applications.

The company is also developing a next-generation system with greater power and longer life than a typical plutonium system. For example, it will scale to 10x higher power levels than plutonium systems and provide more than 1 million kilowatt-hours (kWh) of energy in just a few kilograms of fuel. 

Pretty neat. 

The other company, Avalanche Energy, has developed another device, called Orbitron, which will showcase the ability to reduce the size of high-power propulsion systems for use on smaller spacecraft.

This system utilizes electrostatic fields to trap fusion ions in conjunction with a magnetron electron confinement scheme to overcome charge density limits.

"The resulting fusion burn then produces the energetic particles that generate either heat or electricity, which can power a high-efficiency propulsion system," explains the DUI. 

The DoD and DUI are not the only government organizations exploring nuclear propulsion. For example, the Defense Advanced Research Projects Agency (DARPA) and NASA are also working with the industry to advance nuclear propulsion technology.

They, however, are paying particular attention to how the capability could benefit operations in cislunar space (a term used to refer to the area between Earth and the Moon).

This month, DARPA released a solicitation for the second phase of its Demonstration Rocket for Agile Cislunar Operations program, which aims to develop and demonstrate a nuclear thermal propulsion reactor and subsystem design. DARPA expects to showcase the system on-orbit in fiscal 2026.