Autophage Rocket: Self-Eating Engine Designed by British Engineers As Solution to Space Junk

Space exploration and missions have seen remarkable progress in recent years, thanks to the advancements in aerospace technology. However, these achievements have led to crowding space constellations and accumulating space junk within the orbital zones above the Earth. In a recent study, a team of experts from the UK took the initiative to create a new type of rocket engine that can take a bite out of the huge commercial opportunities of spaceflight.

(Photo: Wikimedia Commons/ Miguel Soares)

Growing Swarm of Debris

The Earth's orbit is home to millions of junk pieces originating from decommissioned rockets and collision events. Also known as space debris, this junk can be as big as dead satellites left in orbit at the end of their mission or as small as paint flecks that have fallen off a rocket.

There are almost 2,000 active satellites that currently orbit the Earth, while there are also 3,000 dead ones that litter space. It is estimated that around 34,000 pieces of space junk bigger than 4 inches (10 centimeters) and millions of smaller pieces linger in this region above the Earth. The presence of space junk causes damage to satellites and triggers more collision events. This increases the complexity of space missions and obstructs Earth-based observations.

Self-Consuming Rocket

On January 10, a team of experts from the University of Glasgow announced the development and testing of an autophagy rocket engine that eats parts of itself for fuel. Known as Ouroborous-3, it is named after the emblematic serpent of ancient Egypt and Greece, which gets reborn after devouring itself.

While the concept of a self-eating rocket engine was first proposed and patented in 1938, no autophagy engine designs were fired in a controlled manner. In 2018, this milestone was achieved by a research partnership between the University of Glasgow and Dnipro National University in Ukraine.

With support from Kingston University, experts have demonstrated that more energetic liquid propellants can be used and that the plastic fuselage can withstand the forces needed to feed it into the engine without buckling. Both of these steps are essential in developing a viable flight concept.

The innovative engine uses waste heat from combustion to melt its plastic fuselage sequentially as it fires. The molten plastic is then fed into the engine's combustion chamber as additional fuel to burn alongside its regular liquid propellants.

This means that the self-eating vehicle would require less propellant in onboard tanks, and the freed-up mass could be allocated to the payload. Since the fuselage is consumed, this system can help avoid the problem of space debris.

The engine was successfully test-fired at the Machlab facility at Machrihanish Airbase in Scotland, producing 100 newtons of thrust in a series of controlled experiments. Compared to a conventional rocket with the same mass, auto-page rockets have greater efficiency and can take a greater payload into space. For instance, they can directly take tiny 'nanosatellites' into space without sharing space on more expensive conventionally-fuelled rockets.