Fusion Rockets Could Potentially Halve Travel Time to Mars: A U.K. Startup Aims to Make It Happen

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The company’s ambitious new Sunbird design aims to harness nuclear fusion in space, despite the fact that commercializing such energy on Earth remains a faraway dream

Margherita Bassi – Daily Correspondent

April 18, 2025 1:01 p.m.

A U.K.-based innovative company, Pulsar Fusion, has recently lifted the veil on a project that has been under wraps for a decade: nuclear fusion-powered spacecraft dubbed Sunbirds. This concept was showcased in a brief video revealed at the Space-Comm Expo in London on March 11.

The Sunbird Migratory Transfer Vehicle is engineered to significantly reduce travel times to Mars by up to 50%, all while providing a reusable platform for deep-space missions. According to a statement from the company, Pulsar aims to collaborate with various missions to facilitate swift transportation of cargo to Mars, supplies to lunar space stations, mining tools to near-Earth asteroids, and telescopes into the vast stretches of space.

Pulsar Fusion envisions the Sunbird vehicles operating from a central base in low-Earth orbit, where they would rendezvous with departing spacecraft, launching them at exceptional speeds toward destinations like Mars or even the distant Pluto. Such capabilities could drastically shorten mission timelines and lower costs for interplanetary exploration. Upon arrival at their destinations, the nuclear-powered rockets would recharge at other Sunbird stations, allowing them to be reused for return trips.

Functioning much like tugs in maritime industries, the Sunbirds reportedly have the potential to reach speeds of 329,000 miles per hour, making them the fastest human-made vehicles ever conceived, as noted by Space.com. While NASA’s Parker Solar Probe holds the speed record due to gravitational assists from the sun, Pulsar claims its models could propel a 2,200-pound spacecraft to Pluto in just four years—a stark contrast to NASA’s New Horizons mission, which took nearly a decade to complete its journey.

However, experts remain cautious. MIT astronautics researcher Paulo Lozano has expressed skepticism regarding the feasibility of such fusion technology, noting the long-standing challenges associated with achieving fusion in compact devices. He emphasizes the necessity of detailed information on the Sunbird blueprints before making an informed assessment.

Currently, all nuclear power industries on Earth utilize nuclear fission, a process where atomic nuclei are split to unleash substantial energy. This typically involves bombarding uranium atoms with neutrons, triggering a chain reaction that produces energy through heat and radiation. Conversely, nuclear fusion merges two light atomic nuclei into a single heavier nucleus, generating far greater amounts of energy, akin to the processes that fuel stars. While fusion holds promise for providing a virtually limitless clean energy source on Earth, the technological advancements needed for practical application remain years, if not decades, away.

As Richard Dinan, the CEO and founder of Pulsar noted, “it’s very unnatural to do fusion on Earth.” He argues that space, inherently, is more conducive to fusion operations since it is a natural environment for such processes.

The fusion mechanism in Sunbirds deviates from current terrestrial studies, which focus on fusing isotopes of hydrogen, such as deuterium and tritium. Instead, Pulsar plans to utilize helium-3 in place of tritium; this approach potentially offers a unique propulsion method, where the positive charge of protons expelled during the fusion reaction could be harnessed to power the spacecraft.

According to Aaron Knoll, a spacecraft engineering researcher at Imperial College London, the timeline for making fusion energy viable for terrestrial power generation may be lengthy, but there’s an opportunity to explore its potential for spacecraft propulsion sooner rather than later.

With its Sunbird design currently in the third phase of development, Pulsar Fusion has set an ambitious target to initiate orbital testing of their technology by 2027. However, the timeline for full operational capabilities remains uncertain, pending the success of its development phases.

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www.smithsonianmag.com