Nuclear fusion:

Meme or dream?

Fusion is a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy (which will be utilized to power homes and industrial processes). The struggle with reaching nuclear fusion is that it requires extremely high energy and temperature to happen. This is because low atomic nuclei such as hydrogen have positive charges. Therefore, for the two nuclei to fuse, the electrostatic force of repulsion (like charges repelling) needs to be overcome. In the core of the Sun, huge gravitational pressures allow this to happen at temperatures of around 50 million Celsius [1]. At the much lower pressures that are possible on Earth, temperatures to produce fusion need to be much higher - above 100 million Celsius. Due to these unfathomable high levels of energy required to start the reaction, our current state of resources and technology are not able to start a nuclear fusion reaction sustainably. However, in the near future, innovation from scientists such as Joint European Torus, the ITER project and the UK-based JET laboratory may change the global source of energy for the better. If nuclear fusion can be successfully recreated on Earth it holds out the potential for virtually unlimited supplies of low-carbon, low-radiation energy.

A glimpse of hope for fusion power has stemmed from the UK-based JET lab which beat by a landslide its own world record for the amount of energy it can extract by squeezing together two forms of hydrogen. The experiments produced

59 megajoules of energy over five seconds (11 megawatts of power) which is more than double what was achieved in similar tests back in 1997 [2]. Dr Joe Milnes, the head of operations at the reactor lab, said “We’ve demonstrated that we can create a mini star inside of our machine and hold it there for five seconds and get high performance, which really takes us into a new realm.” [2]

Additionally, the ITER facility in southern France is said to be the last step in proving nuclear fusion can become a reliable energy provider as it experiments with the 4th state of matter plasma to gradually reach the high temperatures necessary during the second half of this century [2]. This means that those of you reading this will have a nuclear fusion reactor in your lifetime powering industrial processes, appliances, and your homes all without spikes in CO2 emissions and holes in the ozone layer.

References

[1] Nuclear Fusion : WNA - World Nuclear Association [Internet]. World-nuclear.org. 2021 [cited 2022 Jun 23]. Available from: https://world-nuclear.org/informationlibrary/current-and-future-generation/nuclear-fusionpower.aspx

[2] Gibney E. Nuclear-fusion reactor smashes energy record. Nature [Internet]. 2022 Feb 9 [cited 2022 Jun 23];602(7897):371–1. Available from: https://www.nature.com/articles/d41586-022-003911?utm_medium=Social&utm_campaign=nature&utm_sour ce=Twitter#Echobox=1644409150

[3] Nuclear Fusion | IAEA [Internet]. Iaea.org. 2018 [cited 2022 Jun 23]. Available from: https://www.iaea.org/publications/nuclear-fusion

Go Big or Go Home.

It’s a Saturday, and you’re on a boat with a few friends. You haven’t fared well on the trip over, and you lean over the side of the boat to hurl. You stare at yourself in the glassy surface, and smile to yourself despite the circumstances. Today’s going to be fun. A few ripples shift across the surface, gradually growing in amplitude. A low, almost guttural noise sounds across the bay, and the tame ripples grow into small waves. The boat begins rocking, and that noise ascends to a crackling hymn. On the horizon, you see a stick of black riding atop a column of fire, smoke and water. It climbs into the atmosphere, then the stratosphere. The air becomes filled with the excited chatter of your friends.

“Woah,” someone says.

Something Huge.

It holds the respectable title of being the largest rocket ever designed. And that’s no mean feat in

The Early Years

In the years leading up to the 1960s, America had begun to put serious funding and development into their space program. Spurred on by the everpresent risk of technological domination posed by the Soviet Union, progress soon reached breakneck pace.

Yet, for all the recent advances in the frontiers of aerospace research, the price of putting a kilogram into orbit really hadn’t changed. Rather than creating a sustainable, economically viable industry, governments instead focused on grabbing bragging rights for propaganda. The two superpowers pumped what would eventually be billions into the space race to soar higher and claim firsts, but, as a result, all the gains in performance and efficiency in the air just didn’t translate into reductions on the spreadsheets

Despite this, many scientists believed that the key to affordable spaceflight lay in highly efficient engines – if you own a car, isn’t it a good

Truax. missing point. e’re throwing away these rockets every time There’s no point in paying less for an old hack will get the job done

Essentially, Truax believed in He minimizing moving ring benefits two fold. Firstly, in development: using tried-and-tested principles would mean the team could avoid repeating mistakes of earlier rocket designs – as famously not seen in the fuel injector of the F1 engine of the Saturn V – and would lower the overall time and therefore cost of the design stage. It turns out a lot of rockets are actually relatively cheap once the final specification is decided upon – it’s just that getting to that point takes a lot more money than usually expected.

Secondly, a simpler design would mean manufacturing and materials would again be cheaper than those associated with highly efficient and complex rockets, which would otherwise require machining and pressure the key to The Design

It’s hard not be amused by the s the Sea Dragon’s original specifications. taller than the pyramids of Giza and made submarine manufacturer – Todd Shipyards – to minimize costs, the rocket was the epitome of brute force engineering [1]. Rather than precisely machining the body to perfectly distribute loads and stresses, builders would add excess steel plating to protect against mechanical failures. This would have meant quicker and cheaper production, driving down the price of kilo-toorbit.

The engine operated in a fashion not too dissimilar to that of a can of silly string: pressurized gas (in this case, nitrogen) forced the propellants out of the tanks and into the engine.

[1] The fuel and oxidizer ignited, and the gases a garage every time you go to the store.

To counter this, the rocket’s launch pad was the sea: the launch pad could essentially be replaced each launch with no extra charge. The rocket was designed to be floated out from a shipyard, ballasted to vertical and then ignited with its bell 200-300 underwater, all 36 million kilograms of thrust directed into the open ocean [2]

Saturn vs. Sea Dragon’s main engine.

Obviously, there were going to be some major hurdles in overcoming combustion instability. In other words, the engine was going to blow up.

The original budget also left little room for working out the intricacies of the steel body. When compared with the developmental issues of SpaceX’s Starship (also made of steel), the hidden complexity and costs of the project begin to show themselves in a new light.

And the final issue is that of the launch site. A rocket launch is not exactly gentle, and the shockwaves generated by the 36 million kilos of thrust would kill any marine life within a 30kilometer radius. The whole area would be turned into a seafood chowder.

Another proposal floated around was that the fuel for the second stage – hydrogen – could be produced from sea water via electrolysis. The power source for electrolysis? A nuclear aircraft carrier sitting nearby.

Conclusion

Early concept art for the Sea Dragon.

A Few Issues

Truax’s logic and design was fundamentally flawed by no other than the laws of physics itself Now, remember how I said the F1 engine had a few issues with a fuel injector? Well, it turns out that was a result of the size of the engine. The Saturn V had five of those F1 engines, and was considerably smaller than the Sea Dragon. The Sea Dragon was going to have one engine. Ten times the size of the F1.

The Sea Dragon was the ultimate epitome of brute force engineering. Looking at the raw performance, tonnage to orbit and proposed price savings, it’s hard to ignore the allure of the whole thing. Yet the design overlooked fundamental issues bound to surface later in development that would have likely been extraordinarily difficult to overcome, ramping up costs and ultimately countering the whole philosophy of the concept. Nowadays, it's not difficult to imagine a world where this beast got to fly. The things we could have accomplished with the capabilities of this beast would achieve and then exceed the dreams of early science-fiction writers. But in this reality? We’re not going to be seeing it any time soon.

Oh well. At least we have Starship. Watch a simulated Sea Dragon launch here:

References

[1] 1.Sea Dragon [Internet]. Astronautix.com. 2019 [cited 2022 Jun 26]. Available from: http://www.astronautix.com/s/seadragon.html

[2]Avilla A. Hidden Histories: Sea Dragon [Internet]. SpaceflightHistories. 2020 [cited 2022 Jun 26]. Available from: https://www.spaceflighthistories.com/post/seadragon Tarn Timmermans 11CSI