A secretive UK-based startup has just pulled back the curtain on a futuristic space propulsion project that sounds like something straight out of science fiction. Pulsar Fusion, a company working quietly behind the scenes for over a decade, has unveiled plans for Sunbird, a nuclear fusion-powered rocket that could slash travel times across the solar system—and fundamentally change how we explore space.
Revealed publicly for the first time in March 2025, the rocket’s design is bold, its claims even bolder, and while real-world deployment is years away, the concept has the space industry holding its breath.
A Classified Concept Comes into the Light
Developed in “total secrecy” over ten years, the Sunbird concept was announced March 6 and publicly showcased days later at the Space-Comm Expo in London. Pulsar Fusion’s founder and CEO, Richard Dinan, revealed that the project aims to use nuclear fusion propulsion to create reusable “space tugs” capable of ferrying spacecraft from low Earth orbit to destinations like the Moon, Mars, and even Pluto—much faster than conventional rockets.
Unlike rockets that burn chemical fuel, Sunbirds would generate thrust using a Direct Fusion Drive (DDFD)—a system powered by fusing deuterium and helium-3, two hydrogen isotopes that could, in theory, produce charged particles used for direct propulsion.
“If we are going to be the species that actually get to other planets, then exhaust speeds are pretty much the most important thing,” said Dinan. “In terms of what can be [theoretically] produced in exhaust speeds, fusion is king.”
A Radically Different Approach to Fusion
While fusion power is still decades from commercial use on Earth, Dinan argues that it’s actually easier to achieve in space. Unlike traditional tokamak reactors, which require powerful magnetic confinement and extreme thermal control, Pulsar’s linear reactor design could theoretically operate in space’s natural vacuum and cryogenic conditions, eliminating many technical barriers.
Fusion on Earth typically relies on the fusion of deuterium and tritium, which emits high-energy neutrons. But the DDFD uses helium-3, a rare isotope that generates protons instead of neutrons, allowing their energy to be directed into thrust more efficiently.
There’s a catch: helium-3 is extremely rare on Earth and costly to obtain. Future versions of Sunbird may rely on helium-3 mined from the Moon, but for now, prototypes will use inert gas for early-stage testing.
What If It Works?
If successful, the Sunbird could cut travel time to Mars in half, and reduce the time to reach Pluto from 9.5 years to just 4. The propulsion system would dock with existing spacecraft in orbit, like an orbital tugboat, pulling them out of Earth’s gravity and toward deep space—without needing enormous launch stages.
Even more ambitious is the idea of building a network of docking stations throughout the solar system. These orbital “recharge zones” would allow the fusion-powered tugs to operate in both directions, making return trips to Earth faster and dramatically cheaper.
Each Sunbird is expected to be around 100 feet (30 meters) long, clad in thick armor to resist cosmic radiation and micrometeoroid impacts. The rocket’s distinctive “alien-like” design, as described by Dinan, is purely functional—but undeniably eye-catching.
Skepticism from the Scientific Community
Despite the excitement, not everyone is convinced. Paulo Lozano, a professor of astronautics at MIT, expressed cautious doubt about the project.
“Fusion is tricky and has been tricky for many reasons and for a long time, especially in compact devices,” Lozano told Live Science, noting that while the concept is plausible, its actual implementation is far from certain. Without access to detailed technical specs, many experts are holding off on judgment.
Dinan himself acknowledges the uphill battle. True fusion tests haven’t started yet. The company is preparing static tests this year using inert gases inside Europe’s largest vacuum chambers at Pulsar’s UK campus. No helium-3 or actual fusion will be used at this stage, but the tests will simulate how the system might behave.
