“First plasma” has been achieved by Pulsar Fusion’s Sunbird exhaust test system, marking a major step toward developing a direct fusion drive spacecraft capable of speeds far in excess of present chemical rocket technology.
The public test occurred during Amazon’s MARS (Machine learning, Automation, Robotics, and Space) conference on March 23, demonstrating successful plasma control, which will be essential to the safe operation of a direct fusion drive spacecraft. As commercial space flights take on a greater portion of cosmic travel, the direct fusion drive featured in Pulsar Fusion’s upcoming Sunbird Migratory Transfer Vehicle could be the next essential technology.
Harnessing Plasma for a Fusion Drive
At an astounding 4,500°F – 7,200°F, chemical rockets burn at extremely hot temperatures. Such power provided enough lift to carry the more than 100,000-pound launch mass of the Apollo 11 spacecraft from the Earth to the Moon. Yet, with humanity’s eyes on ever more distant conquests that include Mars, engineers hope to harness more powerful and efficient forms of propulsion to help reduce travel times.
By contrast, past NASA missions have taken the better part of a year to send our spacecraft to the Red Planet using current chemical rocket propulsion.
Plasma burns much hotter by contrast: fusion experiments on Earth have reached temperatures in the hundreds of millions of degrees, and the enormous energy involved in this process is enough to increase travel speeds for direct fusion drives far above the chemical rocket limit.
Such speeds could potentially cut the travel time required to reach Mars in half, according to Pulsar Fusion CEO and founder Richard Dinan. The exhaust system of a plasma-based system guides and accelerates charged particles using electric and magnetic fields, and confining that plasma—allowing it to be effectively harnessed for long-distance propulsion—is the major achievement of his company’s newest demonstration.
“The baseline approach is a Deuterium / Helium-3 fuel cycle. While Helium-3 is not currently abundant and would require breeding or alternative sourcing, the trade-off is compelling, significantly higher efficiency, and the potential to displace vast quantities of chemical propellant,” Dinan told The Debrief.
A Growing Space Economy
“This marks the first real step into practical nuclear fusion rocket hardware testing. The Sunbird program showcased this milestone live in California, which was an exceptional moment and a genuine privilege,” Dinan said in a press release.
“There is no greater platform to share this first test fire with than here, surrounded by an esteemed group of world-leading machine learning and robotics academics/entrepreneurs, Nobel laureates, and astronauts,” he added.
Even NASA is pivoting toward greater reliance on a commercial space economy, which is projected to grow significantly over the next decade. Major sectors expected to grow include mining, planetary defense, and deep-space commerce.
“Sunbird is being developed as an in-space propulsion platform rather than a traditional launch vehicle,” Dinan said. “We are actively engaging with established launch providers for integration into existing launch architectures.”
“We are already in discussions with a number of potential customers; however, these conversations are confidential at this stage,” Dinan added. Broadly, interest centers around high-efficiency in-space propulsion for deep space logistics and rapid transfer missions.
Sunbird Migratory Transfer Vehicle
Pulsar is now following up on its demonstration with further development of the Sunbird Migratory Transfer vehicle and its direct fusion drive. The first step will be analyzing the exhaust system to record thrust and velocity data, providing a technical foundation.
To control the magnets that drive the exhaust plume, the company is also developing advanced machine learning tools to adjust them 1,000 times per second. These will close the gap between the difficulty of controlling plasma and the need for a safe and efficient space mission, according to information made available by Pulsar Fusion.
Additionally, the company is working with the UK Atomic Energy Authority to study the leading cause of sustained-use damage to reactor walls and magnets: neutron radiation. Krypton was chosen as the propellant for these experiments, which will provide crucial safety data to estimate the mission’s possible duration.
“Looking ahead, we plan to upgrade the magnetic system to rare-earth, high-temperature superconducting magnets, enabling stronger magnetic fields and the exploration of higher plasma density and pressure conditions,” said Dinan.
“This program ultimately aims to begin experimental work with aneutronic fusion fuel cycles as part of the continued development of the Sunbird propulsion system,” Dinan added.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.