Pulsar Fusion Achieves First Plasma in Nuclear Fusion Rocket Engine, Demonstrated Live at Bezos-Hosted MARS Conference
UK startup Pulsar Fusion demonstrated the first-ever plasma ignition inside a nuclear fusion rocket exhaust system, streaming the test live from Bletchley to Amazon's MARS Conference in California.
Overview
British startup Pulsar Fusion has achieved what it describes as the first-ever plasma ignition inside a nuclear fusion rocket engine, marking a milestone in the decades-long pursuit of fusion-powered space propulsion. The company demonstrated the test live on March 25 from its headquarters in Bletchley, UK, streaming it to Amazon’s MARS Conference in Ojai, California, hosted by Jeff Bezos, according to Euronews.
The test used krypton as propellant and employed electric and magnetic fields to guide and accelerate charged particles through the exhaust channel of the company’s experimental Sunbird fusion exhaust system, according to a press release from the company.
What Sunbird Is
Sunbird is Pulsar Fusion’s concept for a Migratory Transfer Vehicle, a reusable nuclear fusion-powered space tug designed to dock with spacecraft in low-Earth orbit and propel them to interplanetary destinations, according to Gizmodo. Rather than carrying cargo directly, Sunbird would boost existing spacecraft, functioning as orbital infrastructure.
The vehicle is powered by the company’s Dual Direct Fusion Drive (DDFD), which uses two linear nuclear fusion engines designed to burn deuterium and helium-3 in an aneutronic fusion reaction. The resulting plasma would be directed through a magnetic nozzle using superconducting magnets, with the company projecting exhaust speeds of 223 kilometers per second and a specific impulse of 10,000 to 15,000 seconds, according to the company’s press release. For comparison, chemical rockets typically achieve a specific impulse of around 300 to 450 seconds.
The approximately 30-meter vehicle would carry 1,000 to 2,000 kilograms of cargo to Mars orbit in under six months, deliver up to 2 megawatts of power to payloads, and could theoretically reach Pluto in less than four years, according to Gizmodo.
What Was Actually Demonstrated
The March 25 test validated the physical architecture of the Sunbird exhaust system by confining plasma within it for the first time. Pulsar Fusion CEO Richard Dinan called the demonstration “an exceptional moment and a genuine privilege,” according to the company’s press release.
The next phase of development will involve gathering detailed performance data using a thrust balance, E-cross-B probes, and retarding potential analyzer measurements, according to the same release. This data will inform planning for the first Sunbird mission.
What We Don’t Know
Several critical questions remain unanswered. The demonstration used krypton rather than the deuterium-helium-3 fuel intended for the operational engine, meaning the core fusion reaction that would power the vehicle has not yet been demonstrated. Achieving sustained fusion in a compact rocket engine poses engineering challenges distinct from those in stationary fusion reactors, which have themselves not yet reached commercial viability.
The company’s projected performance figures, including the specific impulse range and Mars transit times, remain theoretical. No thrust measurements from the March 25 test have been published. The timeline for an in-orbit demonstration, which Pulsar Fusion has targeted for 2027, is ambitious given the gap between a ground-based plasma test and space-qualified hardware.
Broader Context
Pulsar Fusion’s work is backed by the UK Space Agency and the European Space Agency, and the company collaborates with the UK Atomic Energy Authority on researching neutron radiation effects on reactor components, according to the company’s press release.
The announcement arrives as the broader fusion industry reaches a series of milestones. The space economy is projected to exceed $1.8 trillion by 2035, according to Euronews, positioning faster in-space transport as both a scientific and commercial objective. Future upgrades to the Sunbird system will include rotating magnetic field heating, RF heating systems, and rare-earth superconducting magnets designed to enable higher plasma density and pressure conditions, according to the company’s press release.