Nuclear Fusion Engine Designed to Speed Space Flight Starts Construction

U.K.-based Pulsar Fusion recently started building a 26-foot chamber for its ambitious nuclear fusion-powered space rocket, bringing the years-long project to its next development stage ahead of practical demonstration. 

 

Internal design of Pulsar Fusion’s nuclear fusion rocket engine concept. Image used courtesy of Pulsar Fusion

 

Pulsar Fusion completed an assessment on heating technology in 2021 and then created an initial design prototype. The project now moves to phase 3: manufacturing the test unit in England. The company expects static tests will begin next year, followed by an in-orbit demonstration in 2027. If successful, it would be the first nuclear fusion-based propulsion system to launch into space. 

While fusion rockets remain a theoretical concept, they bring the potential to expand the capabilities of chemical rockets, currently the most common form of high-power engine for space applications. Pulsar Fusion claims its fusion propulsion concept offers exhaust speeds 1,000 times faster than today’s electric propulsion systems. Its Direct Fusion Drive (DFD) rocket system could reduce interplanetary spaceflight to just a few years or even months, depending on the mission. 

 

A rendering of Pulsar Fusion’s rocket. Image used courtesy of Pulsar Fusion

 

Pulsar Fusion’s compact fusion reactor-based DFD produces both thrust and as much as 2 megawatts of electric power to the payloads upon arrival. Packing power and propulsion into one device, the steady-state fusion propulsion system could send a spacecraft with 2,200 pounds of mass to Pluto in four years, compared to about nine years historically. Its projected exhaust speeds range from 246,063 to 782,928 miles per hour (mph). 

For scale, consider the existing track record of flight times for solar system exploration: The U.S. National Aeronautics and Space Administration (NASA)’s Voyager 1 mission flew by Saturn three years after launching in 1977. In 2007, NASA’s New Horizons spacecraft reached Jupiter in about 13 months thanks to a gravity assist maneuver, which then boosted its velocity by 9,000 mph and shortened its total flight time to Pluto from 14 to 9.5 years. Probes to Mars are much faster, historically reaching the planet in under a year. NASA’s Mars 2020 mission saw its Perseverance spacecraft landing on the Red Planet in six months and 13 days. 

Pulsar Fusion argues its technology can dramatically reduce the time it takes to reach those planets. 

 

The Benefits of Fusion for Space Travel

Nuclear fusion can produce the high energy densities necessary for sending humans to space in much less time than today. A critical innovation here is high-temperature superconducting magnets, which generate the fields needed to confine plasma at a high density and accelerate it to a high velocity for the propulsion system. Pulsar Fusion wants its chamber to reach hundreds of millions of degrees, hotter than the sun’s atmosphere (the corona) of 1.8 to 3.6 million degrees Fahrenheit. 

In propulsion, fusion confines plasma inside an electromagnetic field, similar to the sun’s functions. However, per TechCrunch, stabilizing the plasma is a larger challenge Pulsar Fusion hopes to address as it builds its fusion chamber. 

 

Fusion diagram depicting the inner workings of Pulsar Fusion’s propulsion concept. Image used courtesy of Pulsar Fusion

 

The company says fusion offers 1,000 times the power of conventional ion thrusters currently used in orbit. The project targets exhaust speeds exceeding 500,000 mph. Compare that to NASA’s Space Launch System, a deep space launch vehicle that exerted unprecedented power in last year’s Artemis I mission, sending NASA’s Orion spacecraft to the moon. According to NASA, the rocket was designed to accelerate over 17,500 mph while beginning a circular orbit around Earth. Orion was then propelled with a trans-lunar injection maneuver, which produced 24,750 pounds of thrust to accelerate the vehicle to more than 22,600 mph. 

While fusion is largely theoretical for space travel, researchers have already demonstrated the idea in practice for energy. Last year, researchers at the U.S. Department of Energy’s Lawrence Livermore National Laboratory made a significant fusion breakthrough with a controlled experiment that released more energy from fusion than the laser energy driving it. While significant on its surface, researchers are still far from harnessing the technology for limitless energy. 

 

Future Fusion Development

Pulsar Fusion received two grants from the U.K. government and the U.K. Space Agency in 2021 and 2022, respectively. The company is also funding its rocket development by commercializing its Hall-effect thrusters (HET) and hybrid rocket propulsion system for micro-satellites, lunar/planetary landers, and orbital tourism vehicles. 

 

Video used courtesy of Pulsar Fusion

 

Pulsar Fusion is now using advanced artificial intelligence and machine learning to study data from the Princeton field-reverse configuration (PFRC-2) reactor–a novel plasma heating system that could enable a fusion-powered DFD. In a new partnership with New Jersey-based Princeton Satellite Systems, it plans to use supercomputer simulations to understand plasma behavior as it exits a rocket engine and emits exhaust particles at hundreds of kilometers per second. 

With simulations based on PFRC-2’s gas puffing data, Pulsar Fusion hopes to gain the predictive ion and electron behavior needed to inform its closed-loop systems, which would enable a PFRC reactor for rocket propulsion.