Travelling at, or close to, the speed of light seems to be a pre-requisite for truly comprehensive space exploration, as anything significantly below that would probably limit our species to the Solar System or perhaps a handful of other locations in the neighbourhood.
Luckily, some engineers seem to never sleep and keep thinking about big-picture issues even on their free time. NASA employee David Burns has recently proposed a concept he calls “Helical Engine” which could theoretically reach 99% the speed of light without any propellant.
As Burns explains in his paper submitted to the NASA Technical Reports Server, the helical (spring-shaped) engine would exploit the way mass tends to change at close to relativistic speeds in a vacuum.
“The engine accelerates ions confined in a loop to moderate relativistic speeds, and then varies their velocity to make slight changes to their mass. The engine then moves ions back and forth along the direction of travel to produce thrust,” explained Burns.
With no moving parts (other than ions travelling in a vacuum, trapped inside electric and magnetic fields), the engine shows a good deal of promise – at least in theory – but also suffers from a number of not-so-insignificant practical issues.
More specifically – as noted in the New Scientist by Jon Cartwright, as well as Burns himself – to make it work, the engine would have to be about 200 metres long and 12 metres in diameter, and generate 165 megawatts of energy to produce 1 newton of thrust, which corresponds to using a power station to accelerate a kilogram of mass per second squared.
Given that space is a vacuum, however, that might just work. “The engine itself would be able to get to 99 per cent the speed of light if you had enough time and power,” said Burns.
While the paper hasn’t yet been peer-reviewed, and does not contain any specific instructions on how to build such a Star Trek-quese contraption, Burns’ ideas have so far been met with mostly positive responses from fellow engineers and scientists who, while far from sure that an engine of this type could work, welcome their colleague’s enthusiasm and bold thinking.
Those who say we may never reach the stars may turn out to be right. What is certain, though, is that if we don’t try, we’ll never know.