Spaceships of the future could fly from Earth to Mars in just ten weeks using thrusters that don't need any rocket fuel, according to an ambitious new plan.

A British researcher has been awarded £990,000 ($1.3 million) by the US government to develop a fuel-free rocket engine that converts sunlight into thrust.

The four-year study aims to make the concept – dubbed Em Drive – a reality, with the hope of making space travel far cheaper and safer.

However, not all scientists are convinced, with some dismissing the engine as 'impossible' because to work it would have to violate a fundamental law of physics.

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A British researcher has been awarded £990,000 ($1.3 million) by the US government to develop a fuel-free rocket engine that converts sunlight into thrust. Pictured is a prototype of a similar 'impossible' engine built by US researchers

WHAT IS AN EM DRIVE? The concept of an EM Drive engine is relatively simple. It provides thrust to a spacecraft by bouncing microwaves around in a closed container. Solar energy provides the electricity to power the microwaves, which means no propellant is needed. The implications for this could be huge. For instance, current satellites could be half the size they are today without the need to carry fuel. Humans could also travel further into space, generating their own propulsion on the way. But when the concept was first proposed it was considered implausible because it went against the laws of physics. Its allegedly fuel-free nature also means that the drive may directly contradict the law of conservation of momentum. It suggests it would produce a forward-facing force without an equal and opposite force acting in the other direction. Advertisement

Physicist Dr Mike McCulloch, from Plymouth University, will attempt to prove them wrong using a £990,000 ($1.3 million) cash cow awarded by the US government.

The United States Defence Advanced Research Projects Agency (DARPA) hopes the project can revolutionise space travel.

The engine would propel itself using differences in intensity of a mysterious type of radiation dubbed Unruh radiation.

The system is based on electromagnetic drive, or EM Drive, which converts electrical energy into thrust without the need for rocket fuel.

Dr McCulloch will attempt to figure out a workable theoretical model for the engine, providing a blu-print for engineering teams.

'Ultimately, what this could mean is you would need no propellant to launch a satellite,' he said.

'But it would also mean you only need a source of electrical power, for example solar power, to move any craft once it is in space.

'It has the potential to make interplanetary travel much easier, and interstellar travel possible.'

EM Drives like the one proposed by Dr McCulloch are cone-shaped thrusters that use microwaves to create thrust.

The claim is that microwaves bounce back and forth inside the truncated cone, generating thrust toward its narrowest end.

Solar energy provides the electricity to power the microwaves, which means no propellant is needed.

Four of these futuristic engines have been built to date, including one from Nasa, each capable of producing only a minuscule amount of thrust.

When the concept was first proposed in the early 2000s it was considered impossible because it violated a fundamental law of physics.

Its allegedly fuel-free nature suggests the creation of a forward-facing force without an equal and opposite force acting in the other direction — breaking the law of conservation of momentum.

A Nasa image revealing the magnetic fields of an Em Drive, a fuel-less engine that a British researcher is attempting to develop. The concept has generated widespread excitement about its potential to be used in deep space travel

Scientists have previously compared this to placing yourself inside a box, pushing on the side, and generating thrust.

Dr McCulloch's engine gets around this hiccup using a new theory of inertia, which describes the resistance an object has to a change in its state of motion.

Scientists have puzzled for decades over what causes inertia, and Dr McCulloch's theory promises to solve the mystery, while also offering an ambitious new design for rocket thrusters.

HOW DOES AN EM DRIVE PRODUCE THRUST? Dr Mike McCulloch of Plymouth University has a new explanation about how the EmDrive works The EmDrive creates thrust by bouncing microwaves around in an enclosed chamber, and uses only solar power. According to classical physics, the EM Drive should be impossible because it seems to violate the law of conservation of momentum. The law states that the momentum of a system is constant if there are no external forces acting on the system – which is why propellant is required in traditional rockets. But Mike McCulloch of Plymouth University has a possible explanation based on a new theory of inertia. McCulloch's suggests inertia arises from an effect predicted by Einstein's theory of general relativity called 'Unruh radiation'. The Unruh radiation effect states that if you're accelerating in a vacuum, empty space will contain a gas of particles at a temperature proportional to the acceleration. According to McCulloch, inertia is the pressure that the Unruh radiation exerts on an accelerating body. The concept of an EM Drive engine is relatively simple. It provides thrust to a spacecraft by bouncing microwaves around in a closed container When the accelerations involved are smaller, such as is the case with the EmDrive, the wavelength of Unruh radiation gets larger. At extremely small accelerations, the wavelengths become too large to fit in the observable universe. As a result, inertia may only take on whole-wavelength units over time, causing it to become 'quantized.' This means it can only in some multiple of a unit of measure, causing sudden jumps in acceleration. But because of the EmDrive's truncated cone, the Unruh radiation in tiny. The cone allows Unruh radiation of a certain size at the large end but only a smaller wavelength at the other end, according to an in-depth report by MIT. This means the inertia of photons inside the cavity change as they bounce back and forth. To conserve momentum, they are forced to generate thrust. Advertisement

His 'quantised inertia model' links in with something called 'the Unruh effect', which was originally described by Albert Einstein's Theory of Relativity.

It asserts that accelerating objects heat up the cold space around them through black body radiation.

According to Dr McCulloch, inertia is the tiny amount of pressure this 'Unruh radiation' exerts on an accelerating body.

At very small accelerations, such as those experienced by the microwaves in an EM Drive, the Unruh radiation wavelengths become so large they no longer fit in the observable universe, meaning they are 'quantised'.

This is because the photons that make up the waves jump from one wavelength to another.

The propulsion system may make deep space travel like that seen in Star Trek a reality. Pictured is the programme's USS Enterprise spaceship

Dr McCulloch theorises that photons inside an EM Drive also jump from one wavelength to another as they bounce back and forth within the engine.

To conserve momentum, they must generate thrust, which pushes the thruster forward without the need for rocket fuel.

This works similarly to the way that a ship is pushed towards a dock because of waves hitting it from the seaward side.

The QI theory neatly dodges questions over the law of conservation of momentum - as energy is produced via radiation intensity - though it has yet to be proved right.

WHAT IS THE LAW OF CONSERVATION OF MOMENTUM? The basic laws that are applied in the theory of the EmDrive include Newton's laws including the law of conservation of momentum and the law of conservation of energy. At its most simple, the law of conservation of momentum can be explained by studying collisions. During a collision between two objects - object 1 and object 2 - the forces acting on and between the two objects are equal, and opposite in direction. These forces act for a set amount of time depending on the strength of the force and the shape and size of the objects, but regardless of how long this lasts, the time on each object is the same. The EmDrive appears to violate this law because it seemingly produces a forward-facing force that powers it through space without an equal and opposite force acting in the other direction. However, the electromagnetic wave momentum that is created in the resonating cavity travels to the end walls. At this point, the momentum gained and the momentum lost by the electromagnetic wave is equal, which suggests it complies with the law. Advertisement

Dr McCulloch's QI theory received special attention because of the high cost of launching rockets with explosive propellant.

His thruster would be much cheaper and safer - only requiring a source of electrical power to accelerate a rocket.

Dr McCulloch, lecturer in geomatics, believes the study could benefit all forms of propulsion and transport - including cars and planes.

He said: 'I believe QI could be a real game changer for space science - it is hugely exciting to now have the opportunity to test it.

'I have always thought it could be used to convert light into thrust, but it also suggests ways to enhance that thrust.'

Nasa's test set-up for a futuristic EM Drive in its 'Eagleworks' lab. The system is based on electromagnetic drive, or EM Drive, which converts electrical energy into thrust without the need for rocket fuel

The research is being funded to improve the understanding of how to control the interaction of light and engineered materials.

Dr McCulloch will collaborate with experimental scientists from the Technische Universität Dresden in Germany, and the University of Alcala in Spain.

The Plymouth team will first seek to develop a fully predictive theoretical model of Unruh radiation.

A series of experiments will then be conducted in Germany and Spain to test whether the thrust is specifically due to quantised inertia, and whether it can be enhanced significantly.