Can nuclear propulsion revolutionize space travel?
Inspired by the peak excitement of the atomic and space ages of the 1960s and 70s, the entertainment industry dreamed of utopian nuclear-powered futures exemplified by Star Trek, where seemingly unlimited clean energy powered megacities, shuttle pods and star ships on far flung adventures.
Nowadays, whilst some science fiction has become reality – mobile phones, bionic limbs and yes, even hoverboards – that unlimited clean energy source for space travel seems to still elude us.
We’re still in the dark ages for spaceflight.
A rocket ride into space means creating enough thrust to propel yourself and your vehicle up through the atmosphere and escape the gravitational pull of the Earth. The fuel of choice today is chemical energy from burning liquid hydrogen. We call it ‘rocket science’ but basically it’s just fire — the same fire our cavemen ancestors used to cook, keep warm and drive away the monsters in the night.
In the Summer of 2019, a mysterious explosion in Severodvinsk in Northern Russia resulted in the death of two scientists and the release of some unusual radiation. Missile engines exploding are not unheard of — after all their fuel is very volatile! But what was unusual was that radiation spike… what were they trying to build?
The Evolution of the Power of the Atom
We’ve been using the power of the atom for nearly 80 years now — first developed during the Manhattan Project during WWII as immensely distructive nuclear weapons. Some of the first nuclear reactors were developed by Admiral Hyman G. Rickover to power Cold War US submarines.
The civilian transformation of this technology is the generation of electricity in nuclear power plants, creating stable base load, low carbon electricity, (now saving many lives via the reduction of air pollution compared to coal, oil or gas fired power stations).
Currently we use nuclear power for propulsion in two ways:
Firstly, very low energy ‘nuclear batteries’ as seen on the NASA Voyager space probes, satellites and the Mars Curiosity rover.The Nuclear Heartbeat of Space ExplorationAs soon as we leave Earth’s orbit to wander deeper into space, nuclear power is our best and often only choice. Here is…medium.com
These work by using the heat released in the natural decay of a radioactive material and converting it to electricity.
They can just about summon enough energy to power a few lightbulbs and are pretty inefficient – less than 10% of the available power is converted to electricity, although the heat generated is pretty useful for keeping electronics alive in deep space and during the Martian night.
Secondly, some submarines and aircraft carriers have nuclear reactors – like a kettle, a nuclear power plant heats up water to make steam and spins a turbine. It’s what we’ve been doing with steam for hundreds of years – since the industrial revolution!
That rotational energy can then either be used with a generator for making electricity or directly turning a shaft connected to a propeller or propulsor for some happy sailing.
Unlike either of these options, Russia announced it was attempting to build a nuclear-powered cruise missile called Skyfall (too much James Bond, perhaps).
Strangely enough, nuclear rockets have been thought of before, with some weird and whacky ideas (especially in the 70s…it’s always the 70s) and several government funded projects, but they never took off — literally.
Recent Investments
In 2019, the US Congress awarded NASA $125 Million to work on designing nuclear thermal rockets. These work using a nuclear reactor to heat a propellant (such as our rocket fuel of choice, liquid hydrogen), expelling it with much greater force than burning it alone achieves, thus increasing thrust. In the UK,Rolls Royce has teamed up with the UK Space Agency to work on this too.
So why are we interested in nuclear rockets again? Quite simply: they’re much, much faster – so much so that a round trip to Mars could happen in a few months rather than a few years.
This would be the next step in humanity’s journey into the unknown.
Quicker flight times mean you can carry less food and other supplies, and it would make missions cheaper. The astronauts would also be exposed to less cosmic radiation (space outside the Earth’s atmosphere is full of radiation).
Combine that with something like SpaceX’s reusable launch system to enable spaceflight to become more affordable and suddenly Mars feels closer than it ever has.
We are entering a new era of nuclear technological development. Advanced technologies that were not previously practical are now within reach. No human has ever travelled further from Earth than the Moon, but the coming years could see humans reaching Mars and other planets in our solar system — and maybe even beyond.
