Pulsar Fusion, a UK-based space propulsion company based in Bletchley, announced in late March 2026 that it had achieved "first plasma" in its Sunbird nuclear fusion rocket exhaust system — a milestone the company is calling a world first for this class of rocket engine. The demonstration was presented live by CEO Richard Dinan at Jeff Bezos's MARS Conference in Ojai, California, streamed directly from Pulsar's test facility in the UK to an audience of Nobel laureates, astronauts, and leaders in robotics and machine learning GlobeNewsWire.
The test itself was a contained laboratory achievement: scientists created and confined plasma using electric and magnetic fields inside Sunbird's Mark I exhaust test chamber. Krypton was used as the propellant, chosen for its relatively high ionization efficiency and inert characteristics at the mass flow rates required for early testing. The plasma was not harnessed as thrust in this iteration — it was contained within the exhaust architecture, which is the first step toward redirecting that energy out of a nozzle GlobeNewsWire.
The Sunbird system uses a design Pulsar calls the Dual Direct Fusion Drive (DDFD). Unlike a conventional fusion power plant, which aims for net energy gain to supply electricity grids, fusion propulsion has a different objective: channeling energetic particles from a fusion reaction directly out of a nozzle to generate thrust. The DDFD relies on superconducting magnets to form a magnetic bottle that contains the reaction and directs the exhaust. Pulsar claims a specific impulse of 10,000–15,000 seconds NextBigFuture — compared to roughly 311 seconds for the SpaceX Merlin engine in vacuum or about 465 seconds for the RL10B-2 engine used on the SLS upper stage. Pulsar projects that at those exhaust velocities, a fusion-propelled spacecraft could reach 500,000 miles per hour Euronews, enabling a Pluto transit in roughly four years for a 1,000 kg spacecraft — versus decades by conventional means. Those performance figures are Pulsar's projections, not demonstrated capability.
The technical path ahead is long and the gap between first plasma and a working engine is the central honest caveat of this announcement. "First plasma" means the team lit a hot ionized gas inside the device — it does not mean sustained fusion, net energy gain, or thrust production. The next phase involves gathering thrust and exhaust velocity data using a thrust balance, E×B probes, and Retarding Potential Analyzer (RPA) measurements. Pulsar plans to upgrade to rare-earth, high-temperature superconducting magnets to explore higher plasma density and pressure. Eventually, the program aims to work with aneutronic fusion fuel cycles (such as proton-boron), which would produce almost no neutron radiation — a significant advantage for spacecraft hardware since neutron damage is a primary cause of wear in fusion reactor walls and magnets.
That materials challenge is why Pulsar has partnered with the UK Atomic Energy Authority (UKAEA). The collaboration will study neutron radiation effects on reactor walls and magnets GlobeNewsWire, which is the unglamorous engineering work that determines whether fusion propulsion is physically viable beyond the laboratory. This is where the gap between demonstration and flight hardware is widest: a magnetic confinement system that survives sustained neutron bombardment in vacuum, while operating within the mass and volume constraints of a launch vehicle, is a different engineering problem entirely from what was shown at MARS.
For context on where fusion propulsion would sit relative to conventional propulsion: the NASA/DARPA Draco nuclear thermal propulsion program — which used a fission reactor to heat hydrogen propellant, a simpler approach than fusion — was cancelled in May 2025, removing the most concrete near-term government milestone in advanced in-space propulsion. There are currently no active US government programs targeting nuclear thermal or nuclear fusion propulsion. Nuclear Electric Propulsion (NEP), which uses a reactor to power ion thrusters, offers high specific impulse but relatively low thrust, and remains developmental. The cancellation of Draco leaves a gap in the landscape that Pulsar is trying to occupy — but the reason that gap exists is worth noting: nuclear propulsion programs face compounding challenges in test infrastructure, regulatory authorization, and cost that have slowed the field for decades beyond what any single company's announcement resolves. Fusion propulsion, if it eventually delivers on its theoretical performance envelope, would offer significantly higher specific impulse than nuclear thermal approaches and substantially higher thrust than electric systems. Whether Pulsar can close that gap is the open question; the Draco cancellation doesn't close it for them.
With the space economy projected to exceed $1.8 trillion by 2035 — a figure cited by the World Economic Forum and McKinsey — faster in-space transport has a direct economic rationale beyond the scientific appeal. Whether Pulsar Fusion can bridge the gap from this early demonstration to a flight-qualifiable engine is the open question. First plasma is real. Everything else is still engineering.
