Fusion Propulsion 

I’ve gone to bed slightly drunk, to listen to this soldier-scientist spin lyrical stories of our future as the gods of our ancestors and suddenly, the world is alright again.

I like the way in The Expanse the Epstein Drive seems like something which is a relatively minor tweak on existing fusion drives which makes them vastly more efficient.

6:00 - We achieved Fusion this week. We will colonize the solar system. 12/2022

29:30 The stars are rightful human clay!

If a ship travelling at a significant fraction of C was moving through dark matter, wouldn't the gravitational interaction with the dark matter result in slowing the ship by transferring energy into accelerating and 'stirring' the dark matter?

24:07 I'm no nculear physicist so I'm kinda just spouting crap but if we ever figure out how to prevent alpha sticking in Muon-catalyzed fusion to make it viable, since it decays into electron and some neutrinos, could we just get more power?

23:54 no,no,no, that is unimaginable: neutrinos can not be contained nor reflected. Such a neutrino-rocket-engine needs a reactor, where the spin of the quarks of most nuclei has to be uni_directionally oriented, then (potentially, not surely) the produced neutrinos would fly all in the same direction out of the core!

The more complicated, the easier to disable as "Dr. Montgomery Scott did to the Trans-Warp Drive.

Mmmmmmmm fusion torch drives...

Just how much could we use colossal solar sails to slow when approaching a solar system? Say from 5% of lightspeed? 10%?

Imagine explaining fusion to an ancient Egyptian Time traveler: right so fusion is basically the sun in a small container. Egyptian: so you put a god in a can

I love how "we can just make a ramjet with a black hole" is so nonchalantely said by Isaac Arthur. the power scales that are talked about in this channel are amazing!

I was going to build some fusion-propelled spacecraft--but then things got really crazy at work.

Ah yes. The fusion torch drive that spits out a relativistic jet of radioactive iron. My favorite.

As your spaceship shoots a laser at the destination to slow down, the destination puts up a solar panel to get energy from it.

2:14 I once heard someone say "Every car is a deadly weapon capable of mass destruction. Remember that when you're speeding down the road."

"A reaction drive's efficiency as a weapon is in direct proportion to its efficiency as a drive." - The Kizinti Lesson (from Larry Niven's Known Space series)

Don't forget the first rule of warfare: all fusion drives can be used as a weapon.

It's scary to imagine how much destructive power was packed in these fusion torch drives we see in sci-fi, behind that bone-crushing acceleration is the heat to incinerate a planet, such is the power of stars!

Fusion is a reaction in which two or more atomic nuclei come close enough together to form one ore more different atomic nuclei or sub atomic particles. The reaction may reach a stable equilibrium in which it separates from Massachusetts and creates its own thriving lobster industry. This is called the Maine sequence.

"In order to travel between the stars, we will need the power of the stars." A great T-shirt graphic.

"At temperatures of millions of degrees" ...and now that song is stuck in my head.

It is still mind blowing we have fusion reactors now. They just don't produce more power than you put in at least as of right now.

With how bright and powerful starship drives need to be, I feel like stealth in space becomes a "needle in a haystack" kind of stealth once you get enough ships travelling around, instead of being actually "I want to go unseen" because you're always going to be seen, and the trick is not to be noticed among the clutter of other people being seen...

Video idea: Internet between colonies. How will we handle someone uploading RU-vid videos on earth that people on Mars want to see? Surely Mars will have an independent planetary information network, but how and to what degree will we keep Earth-internet and Mars-internet snychronized? Will we do that at all? I'd be curious to see what you have to say about this topic :D

The fact they stacked the floors in the correct orientation is why I fell in love with The Expanse

At 24:39 - you say that you're calculating flight time with constant acceleration *and turnover* for a given distance and you give the following formula: t=√(8d/a) You said "and turnover", yet, you didn't take into account mission apogee, that would have implied halving the distance that is in the square root and multiplying the result out of the square root by 2 giving us a multiplier of 4 in the square root not 8. The actual formula is: t=√(4d/a) I would go into details but it's almost 4 a.m here.

I just woke up early and needed your voice to fall back asleep! 🙏

I like the way the web comic Schlocks Mercenary did kinetic weapons and high speed drives

Why not use a magnetic bottle for fusion. This just needs to be bigger and stronger than our current ones. You could let some of the super heated plasma out at the neck of that bottle wich then go thou a magnetic field than make them move very straight out of your engine. There it is, propulsion directly from a fusion plasma, powerfull and with high exhaust velocity.

Feels awsome to finally watch a vid right after release. Love your stuff man, its amazing for helping me worldbuild.

Surely it’s not a coincidence that you released this video yesterday, the next day the National Ignition facility announces a breakthrough or step forward in Fusion tech?? Did you know Isaac?

The power from fusion drives means you can limit the amount of power you need for the task of acceleration needed. Once you achieve the desired balance of power, then you can make scaled uses of such technology, and all different levels of use can be achieved, shuttles to enormous vessels.

Arthursday = Best day

Hey I recognize that web page 12min in. Atomic Rockets. I love flipping through that site and reading about all the crazy ideas that are out there.

If we could ever have fusion propulsion like they do in the expanse... Acceleration that is so fast and efficient ships can be designed to use that as a means of gravity and flip and decelerate halfway

The ram jet as a means of slowing down is actually pretty awesome. First the interstellar dust and gasses slow you down as you collect them. Then they slow you down again as you burn them as fuel. I imagine you scoop could be modified to serve as a pusherplate for accelerating too. Even a magnetic pusherplate as an extension on a physical one could help add efficiency to a standard fusion drive or might even be useful for ground-based laser or maser driven propulsion.

I can sense deep emotions in intonation when pronouncing Uranus

Hi Isaac. I've had an idea for a rocket engine based on a variation of the VASIMIR ion drive. If nitrogen were used as the reaction mass in the engine, then after being accelerated by the grid the nitrogen ions were neutralized and allowed to recombine into diatomic nitrogen wouldn't that chemical reaction add enough energy to the plasma to bring it close to Epstine Drive levels of efficiency? I'm assuming a fusion reactor driving the VASIMIR. I know it takes a LOT of energy to disassociate a diatomic nitrogen molecule into two nitrogen atoms but going from 2N to N^2 is the basis of many hi-explosives. At least, this could allow practical single stage to orbit. It would be more efficient than a pure chemical engine and more powerful than an ion thruster. I'd love to hear any knowledgeable opinions out there. This idea has been knocking around inside my head for awhile now.

What would be a reasonable maximum relative speed to use atmospheric breaking? Not necessarily to land, but to slow down. For example fly thru/thru the upper part of a gas giant on your way in to drop speed so you can land on an inner, more hospitable planet.

The best part of fusion propulsion is you have artificial gravity for free.

We've (seemingly) yet to realise an affordable, safe, fusion-based form of energy production and storage (nor any viable alternatives, for that matter) because the petrochemical industry gets a severe case of _colonic twitchytitis_ when potential alt-energy candidates surface. For which they remedy by acquiring intellectual property from alt-energy inventors, at whatever amount both party's agree to. Those 'blueprints' are then locked away, never to see the light of day again. This behaviour is documented, continues to this day, and is the single biggest hurdle to the successful development of alternative energy sources.

Excellent series of books that address some but by no means all, of using an Orion drive for moving some quite large stuff. Like stupidly large, multi trillion ton asteriods etc. Called "Live Free or Die" by John Ringo, loosely based around the "Sclock Mercenary universe about 1000 years before that timeline kicks off." or as Howard Taylor said it. "Best fan fiction ever!"

Love all the videos. Seems like i am getting more notifications & you seem to do be doing more uploads than usual..............THAT IS AWESOME. Keep em' coming Isaac. These videos are DAMN GOOD

I still have trouble understanding how something with no mass, (a photon) can impart intertail mass acceleration to something WITH mass. Am I missing something here? Seems that the conversion point- where the interaction occurs, is the only place where mass energy is tranfered when making the exchange of the "push" to it's recipiant for the drive, after that, no push would be present in any form. No matter how fast the photon leaves the exchange is irrelevant to how the conversion occurs.

One my favorite episodes! I wonder if you could have a ship generate beams of positions that the leverage a jet of proton fusing with protons. And if the direction of the protons would make the excess neutrons join in the thrust?

You have no idea how happy this particular upload made me. I've spent the last fourteen days researching exactly this topic.

Getting to the furthest planet in the solar system in 15/16days? So fast it sounds like fiction tbh.

Acceleration/deceleration problem could be solved by using stasis chambers where crew will be frozen until the state of solid matter and then after acceleration/deceleration unfrozen (or remain frozen for duration of an entire flight). Or using transhumans (whose bodies consist of non-organinc matter entirely) as crew members

After being on youtube for years, I just barely stumbled on this channel from the sidebar recommendations.. Love it! Seems a step up in terms of actual content from other similar channels. Any recommendations on great episodes to start with?

A bussard ram jet might be about the only solution, for a spaceship NOT to disintegrate at such speeds..

Why do interstellar spaceships always look so stupid? It's like no spaceship designer knows anything about physics or reality. At 10% of lightspeed (0.1C) compared to the LSR (Local Standard of Rest) the impact of a typical deep space dust particle hits with the same force as a 50-calibre Barrett M82 sniper rifle. That might not sound too bad, but the impact of a grain of sand yields the same as 50-tons of TNT. Any interstellar journey will necessarily involve millions of strikes to the forward-facing parts of your ship. So, you require a shield of substantial size and depth - and it must be repairable. Just a little bit of math shows that to protect the ship at all velocities, and from all predictable impacts, your shield needs to be about twice as wide as the ship - which must be long and skinny, like a pencil. And the diameter of that pencil is going to be at least 400-metres, by the way, so that a drum inside can spin to provide 1G on the floor. Rotating the entire spacecraft isn't possible, sorry. So, any interstellar ship is going to be pencil-shaped, with a reverse-conical nose cone that is the shield, the base of which incorporates dampers to absorb larger impacts. The shield itself is accessed by at least two internal spiral tunnels leading to the surface of the shield, so it can be repaired regularly. God only know what material you can make the shield from, but it has to have some pretty unique qualities, and be about 1,000,000th as dense as titanium. Maybe something like aerogel made from Titanium. Any time you see a supposed interstellar craft with bits sticking out all over the place, and no massive kilometre-thick shield protecting everything behind it, just think IDM; "Ignorant Designer Masturbation".

Fusion is not magic. The rocket equation still applies. I've done the calculation assuming the fusion energy is converted into spacecraft kinetic energy with perfect efficiency. The result is a bit disappointing. You still need huge percentages of fuel if you want to reach 0.1c. Even if you could fully columnate the alpha particles produced by the reaction and avoid neutron waste via an aneutronic reaction (e.g. Proton-Boron) a substantial portion of the energy is in the form of gamma photons. Best case: We find a way to convert those gamma spectrum photons into electricity to power "the habitat" and electron beams to make the exhaust electrically neutral (perhaps add some energy to the plasma to compensate for some of the slower alpha particles).

A laser to accelerate and a ramjet braking system?

I was just imagining a Shkadov thruster powered not by a "normal" stars, but by a Neutron star (engine capable of 43,000RPM lol :D) or a Magnetar, using it's high magnetic forces to work as a tow truck to pull a fleet of vessels! :D

If your ship and cargo are tolerant of high accelerations, you don't have to just brake with a Bussard collector against the relatively thin, randomly moving interstellar medium. You can cut the end of the journey short by running down close to a target star and braking against the denser, highly direction stellar wind. This also should make it easier to kindle a fusion flame as stellar wind should be quite hot to begin with. (You do have to make a judgement call about just how suitable any given star is for this maneuver. Fortunately, any ship contemplating this maneuver is going to be watching that candidate star for several years, with increasing resolution, prior to having to make the decision as to exactly how to conduct braking.)

Tandem Mirror Drive seems most probable.

i think the torch drives of the Hyperion cantos ,although later than Heinlein, are more akin to your examples. awesome vid as always .

this guys accent and voice inflections give him an ET like authority

It's sad that the chances of Humanity leaving for interstellar space are decreasing dramatically as our imminent societal collapse proceeds apace.

This helped me understand how to play modded KSP a little better. Thanks!

Question for Isaac: how have you managed to gather this massive amount of knowledge on science and futurism?

When they make fusion power motorcycles. I'll let them off the hook on the delay of developing flying cars. :)

LLNLab just had a major breakthrough in ICF ignition.

Starfish Prime. Orion is not a practical idea, given what would happen to the planet were those bombs to go off above it. en.wikipedia.org/wiki/Starfish_Prime

Now I want a video on interstellar ramjet concepts, I always found the bussard ramjet idea appealing but was disheartened to hear it relegated to only being a braking solution. Glad to see that there are options out there.

There are so many fusion drive concepts, some are viable, some not But riding something what is essentially a mini star on its own burning at millions of kelvins would be kinda badass

Thank you very much for those formulas at 24:33. How would you set up your equation for more then 1g?

This is one of my favorite topics! Thank you for an amazing episode!

(start of video) it's like you read my mind, sort of...I only just today asked if you could do something on fusion.

My short-term favorite torch drive is the nuclear salt water rocket. But if a starship were built using it, I think I'd like that built in orbit around some other planet. I don't consider myself nuclear-phobic, but that's a lot of fuel, all of it a nuclear hypergolic monopropellant. For long-term, matter to energy conversion. Somehow. Little black holes, inducing proton decay, whatever.

But if you send the fuel for deceleration with another slower ship with tens of years before the passenger ship to be launched, and when second ship reach near the slowest one decelerate only enough to match the speed of the ship that carries fuels from the rest of deceleration. That would need a lot of long term planning I think.

Before I watch, we can expect 5 to 10% speed of light for practical purposes.

What would you do or use to protect the ship and occupants from space debris when traveling.?

This video helped me realize that ships in my worldbuilding project travel at 1% light speed

If we ever develop fusion propulsion the first place we'd visit is the Alpha Centauri system.....which is a really dumb choice in my opinion. The last time I checked it only had 3 stars.

Over millenniums we learned to work with wood, stone, and eventually various metals. Along that way, I'm sure people dreamed and struggled to master the next step. And all that time I am just as certain that others said ut could never be done. Might it be that we are only now in the beginning steps of manipulating energy as easily as we do wood, stone and various metals?

A bit sad I didn't hear about muon-catalyzed fusion drives. While I fully understand that it will never hit a 'break even' point, I have to wonder if it would be powerful enough to none the less serve as an effective drive system if a power source and muon generator could be included.

Happy ArThursday!

"Passengers" had flaws, not as many as your usual Hollywood sci-fi movie but I love the design of Starship Avalon! By angling the inhibited areas and rotated them, a full one gee constant acceleration was unnecessary.

2:57 Your Earth is spinning the wrong way. You're getting sunrise in the West rather than the East as is traditional.

Ha! It rhymes!

9:34 Close but not half the way there since you don't have to accelerate the mass of fuel you already used.

Isaac, can you have the following ... (1) You colonize a KBO object in a specific direction, somewhere 5-10 billion kilometers from the sun, construct a large industrial complex there... (2) construct a space elevator on that KBO that exports large structures (3) construct a linear accelerator radiating outward from that KBO capable of accelerating high mass physical objects to an appreciable fraction of the speed of light (4) ...launching fuel, food, industrial components, etc. (5) you accelerate a large vessel rom the asteroid belt in the direction of the KBO (and beyond which lies a star you can colonize) (6) you overtake aforementioned KBO, find a KBO that's about 5-10 billion kilometers further, and construct a large industrial complex that, we label this complex 00002 (7) repeat steps 2, 3, 4 on complex 00002 (8) launch a second vessel from the asteroid belt, find a third KBO somewhere 10-20 billion kilometer from the sun, construct complex 00003 (9) keep on repeating earlier steps in ever greater increments for "a few hundred to a few thousand times" creating a daisy chain of industrial facilities (10) ... thereby creating a sequence of refueling structures capable of injecting acceleration and eventually deccelleration energy into an interstellar vessel (11) ... let's say one such colonial entity created every year, a constant sequence of vessels underway to build the next chain in the sequence (12) .... let's say ten light years, so let's assume a thousand relay stations might be needed per light year (13) ... thereby allowing a huge interstellar structure ship to maintain indefinite fairly substantial (1G?) accleration and decceleration for the voyage... (14) ... thereby allowing such a "constantly refueled ship" to travel (15) we can of course launch these chainbuilding vessels much more often. They don't need to accelerate at 1G initially. But as more stations emerge in the sequence, we can increase their speed and (over time as technological advances percolate down the chain) their capacity to upgrade on the fly, or build ever more sophisticated waystation structures (16) My guess is we don't need a full ten thousand years to build all waystations, if we launch substantially more often, and as the chainbuilders gradually get more fuel from stations being erected "in their path", laying the sequence might be done substantially faster, say, under a thousand years. (17) and eventual travel times for a fully operational chain might come down to decades for constantly refuelled vessels. And with sufficient capacity you can send a LOT of colonial ships to the respective destinations. Downside is you need a chain for every single star system you want to colonize, give or take. Advantage is this technology works in both directions. I label this project a "Khannea Daisey Chain".

“A ships drives effectiveness as a weapon is directly proportional to its effectiveness as a drive” Quote from: I forgor 💀

Well a National Lab was able to questionabley get more energy out of a fusion reaction for a short time interval recently... depending on where you start the clock. It should he helpful for further advances but is not really feasible for power production. We're close!!!

Economic Fusion Power is always just 20 years out. ;)

I just wanted to mention that in my thermodynamics class, the Bussard ramjet was used in the final exam, so future engineers really are thinking about these kinds of things.

have you ever broken down how the current tic tac UAP's might work? i'd love to see your take on them.

12:57 ooh, nice ship you have there. And is that a deflector shield? That being said, the front shield looks a bit flimsy. I don't think that shield could resist hitting a pebble at 4% the speed of light, let alone 11%.

Didn't like this one sorry :-( Not enough technical details. Descriptions of different fusion engine types would have been great i.e something similar to Scott Manley's video on nuclear thermal salt water rockets from a while back

It's not a cargo bay it is a fuel bunker.

Does this spinning SFIA ship have a name?

Happy ArThursday!

In here after the Fusion breakthrough

The single greatest thing fusion will do for mankind is stop "FUSION THIRTY YEARS AWAY AND ALWAYS WILL BE AMIRITE GUYS HAHAHAHAHAHA *SNORT*" from being posted on every single video about fusion. Anything else is gravy.

I have MIT peer reviewed endorsement of how Noguchi of early 1940s Hamgyong Province achieved muon catalyzed fusion propulsion.

Been waiting for this for a while! I haven't finished watching this video, but is there a chance we could get your take on dV budgeting and interplanetary/interstellar brachistochrone transfers?

First Rule of Isaac Arthur's Fight Club: All Fusion Drives can be used as weapons. Second Rule of Isaac Arthur's Fight Club: Talk about Isaac Arthur's Fight Club because it's interesting.

Fusion - so powerful it makes the earth spin backwards