Researchers at the University of Glasgow have built and fired the first unsupported “autophage” rocket engine, which consumes parts of its own body for fuel.

The design of the autophage engine—the name comes from the Latin word for “self-eating”—has several potential advantages over conventional rocket designs.

The engine works by using waste heat from combustion to sequentially melt its own plastic fuselage as it fires. The molten plastic is fed into the engine’s combustion chamber as additional fuel to burn alongside its regular liquid propellants.

This means that an autophage vehicle can require less propellant in onboard tanks, and the mass freed up can be allocated to payload instead. The consumption of the fuselage could also help avoid adding to the problem of space debris—discarded waste that orbits the Earth and could hamper future missions.

The team’s design developments are being showcased this week as a paper presented at the international AIAA SciTech Forum in Orlando, Florida.

In the paper, the team describe how they successfully test-fired their Ouroborous-3 autophage engine, producing 100 newtons of thrust in a series of controlled experiments. The test fires were conducted at the MachLab facility at Machrihanish Airbase.

The tests showed that the Ourobourous-3 is capable of stable burn—a key requirement for any rocket engine—throughout the autophage stage, with the plastic fuselage supplying up to one-fifth of the total propellant used.

The tests also showed that the rocket’s burn could be successfully controlled, with the team demonstrating its ability to be throttled, restarted and pulsed in an on/off pattern. All of these abilities could help future autophage rockets control their ascent from the launchpad into orbit.

Professor Patrick Harkness, of the University of Glasgow’s James Watt School of Engineering, led the development of the Ourouboros-3 autophage engine. He said: “These results are a foundational step on the way to developing a fully-functional autophage rocket engine. Those future rockets could have a wide range of applications which would help advance the UK’s ambitions to develop as a key player in the space industry.

“A conventional rocket’s structure makes up between five and 12 percent of its total mass. Our tests show that the Ouroborous-3 can burn a very similar amount of its own structural mass as propellant. If we could make at least some of that mass available for payload instead, it would be a compelling prospect for future rocket designs.”

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The autophage engine was one of 23 space technology projects recently selected to share in £4m from the UK Space Agency and STFC last year. The Glasgow team received £290,000 to help establish further pilot testing of the prototype engine.

Dr Paul Bate, CEO of the UK Space Agency, said: “One of the key ways we catalyse investment into the UK’s growing space sector is by backing innovations in emerging areas of space technology.

“The University of Glasgow’s impressive work towards an autophage engine is an example of one which has great potential to meet the growing global appetite for developments in the efficiency and sustainability of rocket propulsion.”

Development of the team’s autophage engine will continue with the support of new funding from the UK Space Agency (UKSA) and the Sciences and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI).