US backs first fusion of fast chemical rockets and nuclear electric propulsion

In the future, there could be a spacecraft capable of maneuvering with unprecedented speed and agility, without the constraints of limited fuel.

The U.S. Space Force has provided funding of $35 million to create a new spacecraft that can “maneuver without regret.”

The University of Michigan is leading a team of researchers and institutions to develop this advanced spacecraft.

The team aims to combine the best of both worlds: the power of chemical rockets with the efficiency of electric propulsion. The key to this breakthrough lies in an advanced power source: a nuclear microreactor.

This technology will provide the sustained power needed for high-speed electric propulsion.

“It will be the first to bring fast chemical rockets together with efficient electric propulsion powered by a nuclear microreactor,” the press release stated.

Exploring microreactor use

Spacecraft propulsion systems generally fall into two categories: chemical rockets and electric propulsion.

Chemical rockets offer powerful thrust but consume fuel rapidly. Electric propulsion, while fuel-efficient, is slower and bulkier, often powered by solar panels.

In situations where rapid maneuvers are required, such as avoiding a collision, the speed provided by chemical propulsion might be essential.

However, electric propulsion could potentially offer much higher speeds.

For instance, a 100-kilowatt Hall thruster developed at the University of Michigan could achieve impressive speeds. However, the challenge lies in providing the necessary power to operate these thrusters.

This limitation currently restricts the practical application of electric propulsion for high-speed maneuvers.

“The space station generates about 100 kilowatts of power, but the solar arrays are the size of a couple of football fields, and this is too large for some of the power-hungry applications that are of interest to the Space Force,” said Benjamin Jorns, associate professor of aerospace engineering and institute director.

The researchers are investigating the use of nuclear microreactors to power faster and more efficient electric propulsion systems.

Multiple teams designing various components

As per the press release, they will develop technologies to convert the heat from a microreactor into usable electricity, which will then power electric engines for thrust.

The propulsion system design incorporates a chemical rocket for quick maneuvers, while a nuclear microreactor provides power for more efficient electric propulsion.

To streamline refueling, researchers are exploring fuels that can be used for both chemical rockets and electric propulsion. These dual-purpose fuels would simplify the refueling process for spacecraft by eliminating the need for separate fuel and propellant tanks.

This ambitious project involves a collaboration of universities and industries.

Ultra Safe Nuclear Corp. will design a microreactor, and U-M engineers will create a heat source to test the system’s other components.

Moreover, they are investigating different methods to extract thermal energy from the reactor and convert it into electricity, including thermionic emission cells and thermal photovoltaics.

Meanwhile, Cornell University has been tasked to design lightweight panels to radiate excess heat into space. The University of Wisconsin will develop a power processing module to convert the extracted electricity to meet the high power demands of the electric engine.