The Spaceship Propulsion Compendium

An in-depth survey of the various technologies for spaceship propulsion, both from those we can expect to see in a few years and those at the edge of theoretical science. We'll break them down to basics and familiarize ourselves with the concepts.
Note: Given that the EM Drive has since been debunked, the error probably doesn't matter, but I made a rather large math error about the Force per Power the EmDrive exerts at 32:10, initial tentative results for thrust were a good deal higher than I calculated compared to a flashlight.
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Cover Art by Jakub Grygier:
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Project Rho:
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More on VASIMR from Ad Astra:
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Mars Society:
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Robert Shawyer explains EmDrive:
• Roger Shawyer Explaini...
Icarus Interstellar:
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[@isaacarthurSFIA]

Author's Note: A bug and and error, so hit like to help keep this comment at the top. Error: I botched a unit conversion on the EmDrive results, re: thrust in terms of Force per Power. The units were in mN/kW for the table I was using and I think I mentally replaced 'milli' with 'micro' since all the results from eagleworks were in micronewtons. This is annotated on the video now but those annotations aren't visible to folks on mobile devices so I wanted it visible in the comments. Those early results are of course very tentative but I still botched my math. Sorry. It's not the first and won't be the last error, and it's not terribly pertinent to the discussion, but it is still a big math screw up. Bug: There seems to be a lot of issues with the closed captions about halfway through resetting to the beginning, but the transcript file and timing are correct, so it's probably a bug, but refreshing seems to fix it. [Fixed now, some weird bug crammed the first ten minutes of the script back into the middle of the episode, I had to manually redo the timing so its probably a hair off]

[@ropegang5186]

Great video man I really truly liked it.

[@4IN14094]

You should put it in the video description, and make a bigass annotation that show up on the part you were wrong, alternative is to re-upload a newer video with the annotation render into the video as people can turn off annotation themself.

[@isaacarthurSFIA]

Um... there is a bigass annotation on it and it is mentioned in the video description, and the former is mentioned in the comment you just replied to?

[@robertostman2075]

regarding cryptocurrency future topic, I hope that you add proper warnings because, the trading platforms are lacking in a lot of things... in fact it seems like video games like eve online have a better trading interface than a plethora of bitcoin markets... scams have been done by any possible way that we could imagine... this is, from hackers, all the way to actual market owners... and the last super suspicious new thing is the conditioned and forced gatering of private info... they not only want your email and phone number... naaa they want your social security number, your tax info, your address, your ID with photo, your signature your... etc etc etc... suspicious??... not at all!!

[@isaacarthurSFIA]

There's definitely security and stability issues with it, and yes I plan to address them as part of an intro on it, though the focus will be more on further-future aspects.

[@KRT054]

Your speech is easily understandable, my friend. You're just fine.

[@baruchben-david4196]

Agreed. Your speech is easy to comprehend. It is no more a challenge than an accent.

[@kjevers1]

I have watched and listened to so many of your videos, I actually don't hear it, unless I'm listening for it. So rock on my loquacious friend.

[@NathanGrass]

I assumed it was an accent until he mentioned it was an impediment. That makes these videos even better, knowing that he is facing a challenge every time he makes one and doing so with style, grace, and humility.

[@mike197714]

I have speech impediment too. But it's not as pronounced. I'm also learning impairment. It takes alittle longer to learn. Joe Biden use to have a speech impediment. Talk to him he'll understand you. I understand you. Don't ever let anyone say differently. You just have a lot to say. Oops I build model rockets from Estes rockets, apogee rockets or I get my rocket kits from Amazon.com. But, currently working on a RPG project to Condence it down so it's easier to understand.

[@timfondiggle2582]

Someone was talking in this video?

[@DTL0VER]

Anything more comforting than Issac saying 'grab a drink and a snack before I start' what a legend! Keep up with the fantastic videos my friend 👍🏻

[@sarnxero2628]

I have my coffee and buttered toast and ready to watch.

[@GregiiFlieger]

... yes there is Gary... When he refers to us or other potential forms of life as „critters“. I just love it...

[@CornerTalker]

Table of Contents 10:20 Laser Sail 12:25 Nuclear Propulsion (Daedalus Fusion Engine) 12:45 Nuclear Thermal 13:57 Nuclear Electric 14:22 electrodynamic tethers 15:08 ion Drives (15:45 Hall, 17:09 VASMIR) 20:45 Anti-matter and Other Photon drives 26:25 Laser Highway 27:10 Diametric / Pitch and Bias 27:54 Bussard Ramscoop and Dark Matter Drive 28:33 Em Drive

[@stephenrosene1505]

+

[@Baalur]

Very nice. Thank you.

[@misterjuca5357]

It should be a hearted coment

[@prodabber0222]

graci

[@joelmulder]

Thank you! Specifically came back to this video to use it as reference material for a concept, and these timestamps really helped me find the bits I wanted.

[@jimmypage534]

Quality and Quantity never thought i would see something as good as this channel

[@isaacarthurSFIA]

Thanks Jimmy!

[@scoutofthe107th]

he has so many long amazing videos and does them so often, i know right!

Right on.

[@absalomdraconis]

For those curious, Q-factor appears to originate from AC/oscillator design, where it essentially indicates the "quality" (narrowness and regularity) of oscillation. In the context of this video, it has been conflated with low resistance/impedance (which are related to each other, passingly like a tiger is related to "the big cats").

[@adamanderson3042]

He was right about the EM drive stuff. Since this video was released it has been fully confirmed by consensus and peer review and all of the proponents of EM drives that the tiny bit of thrust was due to outside influences I believe one of the main ones was literally momentum created by the electrons travelling through wires, crazy.

[@bowlerballer6852]

true, kind of crazy that so many people bought into the idea that the EM drive, which is essentially just a perpetual motion machine, would work

[@catprog]

I think that electrons movement was generating a magnetic field. That was interacting with the earth's

[@FinleyESB]

Mate, you really don't need closed captions because of your speech impediment. I love your videos and find your knowledge mind boggling and fascinating. Your videos are my go to choice at bedtime. I love relaxing and ingesting your fountain of knowledge. Even if I do struggle to understand some of it. Keep up your great videos, us mere mortals rely on you for our fix of space and the unimaginably huge universe that we live in.

[@Pharozos]

While I agree with you, It is still useful to those with hearing problems.

[@thomasr.jackson2940]

He speaks clearly, just sounds different than some expect. More like an accent. People still freak over different though. But captioning is a great service, for lots of people, for lots of reasons. I routinely use captioning, especially for educational videos. My hearing is fine, but I find visual material a lot easier to absorb than auditory. And if I have problem catching a phrase or its meaning, I just click pause on the remote and read it a couple of times.

[@Saxie81]

Cam F sorry Cam, just grown ups here.

[@bozo5632]

I almost agree, but captions might be good for non-native speakers - and bad listeners.

[@4vediotube]

Saxie81 I have always been curious about the possibility of macro-structured nano printed arrays using the accelerative effect of electrically charged carbon nanotubes on streams of laser cooled Rubidium atoms. Thrusters?

[@gaiusjuliuspleaser]

If we crack fusion it'll be like discovering actual magic...

[@isaacarthurSFIA]

In a lot of way, yes :)

[@gaiusjuliuspleaser]

It'll be magic to me, at least :P Honestly, when I think about the breakthroughs and discoveries they will make over my lifetime, I get just a little bit giddy. I'm 30 now so I'd say I have at least another 50 to go if all goes well... Who can even tell what will happen during that time?

[@isaacarthurSFIA]

I figure, being 36 myself, we should be in for a lot of technological wonders in our lifetimes :)

[@gaiusjuliuspleaser]

I do hope that one day, when humanity lives in a vast Dyson swarm around the Sun, they will look back on this period in time as the beginning of it all, when humanity began to realize its true potential for reaching the stars. Let us hope we don't squander it.

[@theultimatereductionist7592]

I am 52 and I have attempted suicide several times this year, in preparation for this election. And the worst has come true for the USA with the election of an antiAmerican freedom-hating piece of excrement Donald Trump for President. The only way to change people's minds is to exterminate them. They are too stupid to educate. Killing them makes them permanently logically consistent. I have given life my all & I have lived a good full life. Earned my PhD & MS in math & published in math in the field of differential algebra, and an A.S. in Biotechnology & a BChE Chemical Engineering, published papers. Have worked on multiple applications of my math. But the world does not want my help, does not want my work. So suicide is the only option. Fuck political correctness. I will torture & kill anyone who dares take away my freedom of hate speech.

[@jomgelborn]

Don't worry about your speech impediment. It's a very minor thing. Thank you for the video.

[@SoulDelSol]

I'm sure he doesn't worry anymore. I'm glad he mentioned it tho, addressed it head on, bc otherwise there would be all kinds of comments ppl asking rude questions

[@rebelbeammasterx8472]

I don't even notice it.

[@afielsch]

Yeah I was wondering about that. What speech impediment? I just started the video and am at 1:56 now - so maybe I will understand soon. So far tho, nothing. Cheers

[@Aanthanur]

since he mentioned it, i am wondering what impediment he was talking about, can't hear it, understand everything perfectly fine.... maybe its because my english sucks as itsnot my first language....

[@brucehunter8235]

I think it's cool! He sounds like Homestar Runner! :D Great video.

[@theknightskyisi]

9:39 You don't move the earth when you jump you introduce a pressure wave into the ground and the mechanical energy of that pressure wave is dissipated as heat or is invested in compressing mass. When thinking about the physics of the earth people often make the mistake of treating it as homogeneous and totally rigid no planet sized object is rigid enough to be moved by a person moving, you're more likely to introduce flexion into its structure. P.S. I discovered your channel today and I love your work and how your brain works. You're so thoughtful, thorough, considerate, and intelligent. I've loved testing my fiction universe against your conclusions and looking at it even more critically. I haven't caught a significant shortcoming in it yet and I hope my winning streak continues. Edit: made compliments sound more genuine.

[@Vectorlover3]

so nice to find a channel that can just impart valuable and enlightening information without the need to be geeky and zany. I've grown quite sick of clicking of space news vids to be hit with zany child like presenters. Any ways a great video that seemed to prempt the questions arising in my head. You forgot one important type of engine...The infinite improbability drive! i've subscribed, cheers.

[@chrisbenson5721]

I couldn't agree more, i really like the way he presents facts without acting like the audience are a bunch of 2 year olds.

[@KatherineClairmont]

do people really have difficulty understanding you? I find you easy to understand.

[@janchovanec8624]

People like to complain and make fun of other people though.

[@michagrill9432]

My biggest problem is his accent but that's because english isn't my first language and I'm not used to that particular accent. I guess as I watch more videos it'll get easier to understand

[@ahumanbeingamnayplaceholde1746]

Same here, it sounds more like an odd accent than a speech impediment.

[@nightmarestudios.4833]

He speaks uwu language

[@flaparoundfpv8632]

I have a hard time with it. Great content tho.

[@theCodyReeder]

I'm not finished with my video but it should be out in a couple hours. ok maybe more than a couple...

[@isaacarthurSFIA]

I'm looking forward to it, I'll card it and link it when it does. Thanks again Cody!

[@NectarinoMo]

Hope ye found some gold in them hills.

[@SoulDelSol]

it's out, Cody sent me. dude's ambidextrous. what can't he do

[@nicevideomancanada]

NileRed is better in my opinion

[@anandsuralkar2947]

Hii

[@Drew_McTygue]

I already know this video is awesome, cuz i saw the script! thanks for making this Isaac it was alot of fun pitching a topic for your awesome channel!

[@100001091057100001]

same ways, they do. like ,cult prophecies and pipeline profit is linked by frauds who will kill followers. in afghan or Golan Heights

[@uldypadron424]

100001091057100001 1 class nm

[@Kojima93]

Your videos are educational and very fun to listen to. I find them calming and very interesting. The conclusion pf the video regarding how journalist publish everything is very true and has made me more aware of what I read and what i take for fact. thanks again.

[@pilotavery]

This is the only channel where videos over 10 minutes are actually quality enough to watch the whole thing.

[@lazaglider]

I do enjoy finding absolute gems of channels amongst the dross that is youtube. This is the first of your videos that I've watched, and it will not be the last. Superb, absolutely superb.

[@isaacarthurSFIA]

Thanks! I hope you enjoy the others... though I might suggest staying away from the earliest episodes. :)

[@lazaglider]

Thanks, I'll work my way backwards!

[@smokeythebear1633]

Not only is your speech understandable, it is downright comforting. Love the videos.

[@killerinstinct2000]

Hey Isaac, I started watching your channel a few weeks ago. I know in a few videos you mention your speech impediment. I have to say, after listening to a few videos I don’t really hear it anymore. I personally find your voice very soothing. I am glad you do what you do. Keep blowing minds.

[@cyclingnerddelux698]

Agreed

[@conceptionrabe2797]

Its unreal that so many videos of this quality is posted for free on KZbin. WOW. You deserve a super-massive raise my friend! Your series is worth millions for sure.

[@antoismith]

Your channel is awesome! I have been watching you for a while and have noticed that your subscribers are growing very fast. Congrats on the success. Hope the channel gets huge and I cant wait for the next video. Keep up the great work!

[@swedishdissident3406]

I did not notice anything even after you mentioned it. You are much clearer and understandable than many KZbinrs if anything one of most clearest.

[@ВладКузь-з7ч]

Damn, I'm so glad I found your videos. Not only are they so thorough in research and content, but also captivating, Nice Job!

[@isaacarthurSFIA]

Thanks Vlad, glad you enjoyed them!

[@kabirhanda7817]

I've watched every single one of your videos...and I can't get enough. The quality of your videos are on another level compared to other similar videos on youtube. Please continue what you are doing I am sure to say we are all grateful!

[@isaacarthurSFIA]

Thank you Kabir!

[@XxHybridFreakxX]

I realize this is 3 years old but I just found your videos and I'm loving them.

[@palfers1]

I do wish we'd start actually using some of this stuff. At 2 gee accelerate/brake, the Moon is only 2.5 hours away! It's a bloody day trip.

[@rustyspace900]

Or just one G, we could just walk around the spaceship like on Earth :D

[@jeechun]

Also vote for 1G: less than 1 hour is the difference for trip time (3.4 hours), but in comfort.. :)

[@jfrtbikgkdhjbeep9974]

woooohoooo !!!! 😳

[@GatorNick]

I freaking love this channel. Stimulating the mind one video at a time.

[@jakeownsbey9858]

This makes me want to go play Kerbal Space Program

[@HieronymousLex]

I don’t think I’ll ever stop going back to ksp, it’s the best game ever. If anyone is reading this and hasn’t played ksp, go download that shit right now because if you like space you need to play it

[@ahumanbeingamnayplaceholde1746]

Try the KSPIE mod, it contains most of the propulsion systems listed in the video.

[@extra4594]

@@HieronymousLex whats the prices looking like??

[@jasoneversole151]

Sir after watching just one of your videos I was hooked. No lie. I leave your playlist going all night while I’m asleep and then when I get time through the day I watch them again. The way you impart the technical knowledge in a manner that is both easy to understand yet doesn’t sound demeaning to the listeners is brilliant. I became a subscriber instantly and look forward to everything you put out. Well done sir

[@stevetaylor4232]

got sent here by a video plug of cody's lab and i must say sir i am thoroughly impressed, +1 and subbed

[@colemarie9262]

Thank you for doing what you do, please never dumb down or shorten your content to fit the internet age attention span. It’s so rare to find science based channels that aren’t superficial clickbait at this point.

[@Itb7]

ahh yes, Project Rho. It's like the Home Depot of rocket science- you just want to use _everything_.

[@isaacarthurSFIA]

Very well put :D

[@addammadd]

4 years later, having been through all your videos, I now put these on when I want to grab a nap and a think. No irony whatsoever, your voice is basically my white noise machine these days. Wish I had you to whisper in my ear between QRF shifts during OIF lol.

[@martiddy]

17:22 Never thought that Franklin Chang would be that important in rocket science development, he is from my country though.

[@difdaf436]

Honestly Mr Arthur, you are one of the great minds of our time, I do hope more people get to appreciate the brilliance of your work

[@stevennash1979]

Longer the better. Great vids.

[@Azdin1990]

I absolutely love your videos. Please keep up the good work. Once I'm done bleeding money for school, I'll definitely be donating to your Patreon. I've watched all of your videos, and we need more people like you.

[@isaacarthurSFIA]

Thank Sol, hopefully we'll see a nice rise of in-depth science videos in the future, personally I'm still getting a kick out of making them :)

[@32353235e]

fission fragments thruster eactor

[@julienguieu5636]

After 10 years watching stuff on KZbin, the genuine awesomeness of your channel has motivated me to hit "subscribe" for the very first time. Thanks a million for the mind-tickling info & visuals, and for the time & work that go into it. Ever since I first learned about the acceleration of the universe's expansion, I've been pretty bummed out about our long-term prospects, but watching your videos makes me think our descendants will actually have plenty of time to experience plenty of cool stuff we can only dream and muse about. And for that, too, I thank thee. Godspeed!

[@isaacarthurSFIA]

Welcome to the channel Julien, and yeah I know what you mean about the accelerating Universe being a bit grim, I think that's what encouraged me to think about the Black Hole Farming concept.

[@craigfulton3316]

Your speech is fine buddy anyone says different fuck them good job mate.

[@pipedemon28]

English is a second language to me. I'm glad you mentioned your speech impediment. It is very light and never interfered with the ton of learning I'm graced with on your channel. I like how your theses are based in scientific principles. Keep it up

[@MrMichael1701]

Hey, I just ate some eggs and doubled my exhaust velocity ! : D

[@mickeyg.c.1654]

What's most amazing to me about you and people like you, is that you are what I would consider normal and I, unless watching a video where you are explaining things to me, am somehow substandard. Absolutely fascinating. Not just the material you cover but the fact that you could make a brain like mine understand it. Thank you so much for uploading!

[@cpnCarnage666]

ou play kerbal space program? i imagine a nice side project of you and scott manly talking about space and stuff

[@FuriousImp]

Ditto.

[@B0bb217]

Also ditto

[@B0bb217]

Scotts astrophysics vids are awesome

[@isaacarthurSFIA]

Surprisingly no, its been on my list for quite a while. I don't get much time for games of late, I've been playing one called planetbase, hopefully when winter comes I'll have a little more time. These videos have sort of become my video game though. :)

[@AngelOfDiscordia]

Manley + Arthur needs to happen.

[@arlaban22]

One of the best channels on KZbin. ..without a shadow of a doubt.

[@fusion9619]

hold on, you can keep getting acceleration from a laser beam between two mirrors? Shouldnt the light degrade to lower and lower energy, via longer wavelength, until there's no more force to impart? How long could that go on?

[@doppelrutsch9540]

The impact would get slower and slower, both by light escaping to the sides, being absorbed by imperfect mirrors and doppler shift. But theoretically it would keep on exerting a force without an absolute limit.

[@Auxf5]

I'm pretty sure the point others have tried to make is that diffusion becomes an issue long before doppler shift. I'd also point out that aiming such a device seems impossible to me. The current first bounce would be incoming at a different angle than the second bounce, unless your "stationary" mirror is wider than, say, the earth's orbit. Keeping the "home" mirror "stationary" would be more expensive than just blasting new photons at the thing, or at least that's my guess.

[@the1exnay]

Auxf5 My bet for aiming would be retroreflectors, though that might require more mass than just a flat mirror

[@the1exnay]

Auxf5 Ooh, and if you add in light amplification systems like you use to make lasers but between the two retroreflectors then you dont even have to aim the origin laser, any light bouncing between the ships would self-aim and amplify

[@AbominableHuman]

This channel is like the perfect channel for me. KZbin needs more people like you.

[@conveyor2]

It's almost 2018 and the Em drive is still in the 'unproven' category. Any sign of a resolution or is this going to become just another cold fusion type claim?

[@HuntingTarg]

It's been officially disproven; the appearance of thrust was an artifact of the measurement apparatus. See Scott Manley's videos on the initial publication: kzbin.info/www/bejne/gHjGp6udbM99itU and later findings: kzbin.info/www/bejne/qHuwZ5-Gbqioidk

[@TomCollura]

Great Job Isaac.I Actually didn't even knew you had a speech impediment. Your science is good, reading and narrating skills, GREAT! I love these videos. Keep em coming!

[@thagrit]

Take a look at thorium reactors. Either molton salt reactor or liquid flouride thorium reactor.

[@triularity]

A thorium reactor in zero-G/microgravity would be interesting since the safety feature of a plug that melts on overload and drains everything to a non-reactive tank typically depends on gravity.

[@RaysHobbies]

The old vids audio is amusing now. Nice how far you've come

[@RusZugunder]

Either your speech has improved, or i got used to it :) Anyway, nice video, and the whole channel really, thanks for your work!

[@isaacarthurSFIA]

:) Probably both, and thanks!

[@Matracokura]

Extra points for the projectrho mention. Not a native english speaker, but i can understand you perfectly. Pretty much the only thing i hear as amiss is computor instead of cumputer. Superb content, subscribed after watching one video, after stumbling upon your channel. If you manage to keep this quality up, i can see a lot of subs in the future.

[@SuperJg007]

You are awesome bro. Your speech impediment is no problem. You give something more than information, you give people hope. You give people a chance to look forward to something and in a meaningless world that's a great thing. So I would like to thank you. :)

[@doppelrutsch9540]

Did NASAs EM-Drive really have less force/power than a photon drive? I thought it was at least an order of magnitude more which is why people got exited.

[@isaacarthurSFIA]

Not confirmed, that I'm aware of anyway, I've seen a lot of accounts that NASA got higher, like hundreds of nano-newtons per Watt, when light gives you about 3 nano-newton per watt, but I'm not aware of that being official and as the minimum, rather than a maximum upper-bound. I could be wrong.

[@doppelrutsch9540]

Isaac Arthur Looking at the collection of results at the EM-drive wiki, most that did report some force were quite a bit higher: emdrive.wiki/Experimental_Results But then, this is about as official as me claiming it on a youtube comment^^

[@isaacarthurSFIA]

Yeah unfortunately. That's the problem of course, it looks promising exactly because there's some signs it might be out doing light propulsion, and of course the lack of propellant, but solid evidence it is doing so is what eagleworks is aiming for and until there's a peer-reviewed paper on it from them or another solid lab we haven't really got anything.The other issue of course is it is so hard to measure that tiny of a thrust that margin of error bars and possibility for noise make the upper bound dubious at best.

[@doppelrutsch9540]

Isaac Arthur Sure, the noise in some of those tests (especially the TU Dresden one) was just horrible. I'm just asking where you got the figure for it being less powerfull than a photon rocket because I never found that anywhere, whenever somebody claimed thrust it was at least 10x as much.

[@ВіталійЛуцан]

all the hype was because of that drive pretty much work without fuel despite momentum conservation law, not the power output (wich was tiny)

[@jarrodeverhart9072]

Stumbled into your channel about a week ago, love it I watch these everyday, thank you for the work you put in.

[@DrIBeast]

EM drive review paper was released do a video!!! please

[@bobbarker8732]

shit... Imma have a speech impediment before long. I've been binge watching for a week now and loving the topics.

[@theultimatereductionist7592]

Logic demands I give you HUGE praise for your EXCELLENT survey of all these different types of potential or real propulsion systems. Kudos! You clearly know your stuff VERY well. You are NOT one of these idiots who completely ignore basic thermodynamics & conservations laws: energy, momentum, force balances at points. I know I am nihilistic (my other comments) - but I am always hoping/waiting to change if others can prove to me otherwise.

[@isaacarthurSFIA]

Thanks. Nihilism is always a tricky mind-trap to avoid, and I'm afraid I know of no strong counter argument to it, beyond a sort of Pascal's Wager approach of just comparing the two options, none of this matters vs it does matter and if you choose to assume it doesn't matter vs assuming it does. Of those 4 options the only one you really come up on the losing side of is if it does actually matter and you choose to assume it doesn't. That obviously has nothing to do with determining the truth, but where there isn't particularly feasible it is handy for picking one's approach to life.

[@AtilaElari]

I'm a bit confused that you did not mention more "down to earth" propulsion methods, already doable or almost doable with our technology. My favourite being "steam rocket", a rocket that carries it's own reactive mass but gets the energy elsewhere - most likely ground-based power plant. That would not make it much more efficient in therms of specific impulse, but make it much cheaper. Your rocket will not be a super-complicated masterpiece of engineering powered by highly-refined fuels, but rather a big tank of liquid hydrogen (or even plain water if you can dump enough power quickly enough into it) with some basic exhaust vectoring coated in absorption material. Then you focus high-powered laser or maser on it to get the contents boiling and have a nice thrust. Naturally there are some drawbacks, like problems with atmospheric scattering of the laser\mazer beam or that you need the line of sight with the rocket at all times. But it seems like a reasonable first-stage engine, mostly because of the costs. Alternatively it can be used in asteroid mining - you would have a relatively large fission reactor or solar farm on your asteroid colony and on Earth orbital spaceport, and you can send dirt-cheap transport ships that are just ice-filled tanks with some cargo attached between those. It's not the most efficient way, but it seems to be a lot cheaper one.

[@isaacarthurSFIA]

I did mention cold gas thrusters I think, but time constraints, the actual request was for newer cutting edge stuff.

[@AtilaElari]

While I will be the first one to say that learning about new, high-tech and cool ways to get to space is awesome it'd also be interesting to see a video about some low-tech ways to get there. Low-tech as in not relying on brand-new fundamental science, but rather requiring better engineering. Like the steam rocket I mentioned.

[@isaacarthurSFIA]

I should dig out some of the old papers I wrote on anachronistic tech some time, you'd probably enjoy them :) Bronze-age tech to make refrigeration, that sort of thing. I've always been tempted to do a series on that. You're right of course, good old fashion steam or hydrogen or even just compressed gas can be a very good propellant.

[@AtilaElari]

It's not so interesting now when our main concern is getting off the planet. But once we start mining asteroids or Moon, cheap and simple, even if inefficient propulsion systems will most likely be in high demand.

[@thekaxmax]

Atila Elari he mentioned external power rockets.

[@krissisk4163]

Your videos are very interesting. I love that you're tackling these things. The sort of stuff you tackle is exactly the stuff I love seeing.

[@isaacarthurSFIA]

Thanks Kris!

[@AZOffRoadster]

Speech issue? Over it... within first viewing. I've worked with some of this worlds smartest people. A speech impediment ranks low. I liken it to a coworker who thought in parallel, and had problem trying to speak serial.

[@Brizz-rc2wf]

I can understand you because my youngest brother had the same speech impediment until he was 11-12ish but it’s so cool and polite of you to provide CC. Love your channel man.

[@1DanConnors]

This is an idea I have been trying to draw peoples' attention to for decades. It does not use advanced technology. In fact the fuel I selected is considered too slow for an advanced propulsion system today. It is UDMH and the oxidizer is N2O4. Both these liquids are storable, though, and that's why I selected them. Basically the idea is to use the C-5 airlifter as an efficient first stage for a rocket to orbit. The C-5's basic maximum payload of 240,000 pounds is bypassed, and a rocket massing at least 400,000 pounds is air dropped from the equator at an altitude of 25,,000 feet. The rocket that is loaded on the C-5 has a mass of 150,000 pounds, including 125,000 pounds of UDMH (unsymmetrical dimethyl hydrazine the fuel used in the Titan 2 ICBM). The plane then flies to the equator, burning about 300,000 pounds of its on board fuel plus a refuel by an accompanying KC-10 tanker if needed. A specially modified KC-10 then rendezvous with the C-5 and transfers 250,000 pounds of nitrogen tetroxide oxidizer through the aircraft pumps and into the empty oxidizer tank of the rocket. The back clamshell doors of the aircraft are then opened, after it has slowed to about 220 knots. The rocket, now massing 200 tons is extracted out the back of the cargo bay. At a safe distance ( a 2,000 foot drop) the main engines are ignited. In all the simulations I ran this rocket can deliver from five to six tons of payload to a 300 mile circular low Earth orbit.. The turn around time on the C-5 aircraft should be only a few days. It would be the only part of the launch system recovered, unless a manned rocket was the payload. A six ton payload is not much. The selling point would be that many such launches could be made per year. At one launch per week the system could put up 300 tons of payload per year.

[@gagarinone]

Why don't you build a small prototype? Surely Elon Musk, Planetary Resources and/or Deep Space Industries will be interested. Get in touch with Peter Diamandis. He could possible make your idea going forward.

[@logangagnepain7154]

I love how much Isaac has owned his speech impediment over the years. Hes become such a center for discussion within the community

[@altha2008]

His speech had gotten a lot better mine is getting worst due to speech impairment and having Parkinson diases lot of time I just say very lite anymore when talking to people

[@omegasrevenge]

Yes please, GET INSIDE ME!

[@CozymfDQ320]

U wot m8

[@digismartuk]

This is brilliant, intelligence, narration skills and the ability to keep things interesting are what defines this not your voice! Keep at it bro you rock

[@ferret1337]

subscribed with an open heart! love your music choice and technical knowledge!

[@alexkramerblogs]

Found a new channel to binge through! Thanks, Isaac!

[@mickidawop414]

I love this channel! LOVE LOVE LOVE IT!! I sometimes get so engrossed in the topic that I forget to hit the "like" button, but as I sit here sipping tea from my Isaac Arthur mug, I LOVE THIS CHANNEL!!

[@deanlawson6880]

What a great video! I am fortunate to have stumbled onto this Video Channel, off of a link someone posted in a comment on a post on Facebook! Very Cool!! Thank you for taking the time to research and produce these excellent videos!!

[@isaacarthurSFIA]

Thank you Dean, and welcome to the Channel!

[@artemis360]

It's nice the way you're so considerate with the captions but I personally have no problem at all understanding you. Brilliant videos, man.

[@isaacarthurSFIA]

Thanks Artemis, some folks have a harder time than others with it, it seems to be regional.

[@thepigeon7316]

I find your speech to be easy to understand and really relaxing. These videos are my new thing for a relaxing drift off to sleep while learning.

[@projectexplore7886]

Thank you for making these videos. I really appreciate it as it's interesting and gives me something to listen to while at work during my monotonous day.

[@politicallycorrectredskin796]

My experience with simulators definitely confirm that orbits are the tricky part, not the rocketry. Stick a can of fuel on a stick and light it up and your stick is definitely going somewhere. Where it goes is just very difficult to predict, though.

[@mixpick138]

Gawd, I just stumbled on these videos recently --my bad! These fantastic nuggets of information are what I hoped the internet would be all about. Bravo Isaac and many thanks for your great work!

[@frankmarburger6587]

Isaac's your pediment doesn't bother me whatsoever I enjoy your programs they're pretty awesome. Keep it up I enjoy watching

[@danbreeden8738]

Yours is one of the best channels on KZbin

[@kylemcclureazadsalahazadi]

Your unique speech is a huge reason that my sons and I are subscribed to you.

[@jordanhampton7144]

I'm hard of hearing but your speech does not cause me any issues. Thank you for speaking clearly! I can understand you better than many!

[@richarddeese1991]

Mr. Arthur; first off, thanks for another top notch video. And second, you should not have to apologize for the way you talk or sound. Let people make of you what they will - just as anyone else would have to! You're perfectly understandable; let haters hate! tavi.

[@jamesodom4980]

You are my favorite narrator.

[@lastsonofabraham2678]

Thank God I found this channel ,it answers all the questions I've been asking for a long time

[@arroraseliant8482]

I dont have remotely enough time in my life to watch all of your videos, yet i wish i had, Without rival the best SF related series on the site.

[@colinburfeind6947]

This is one of my favorite videos out there. I’ve listened to it many times and based an awesome science report last year on it.

[@Mark.1980]

Even with the impediment your videos are still more enjoyable to listen to than some of the droney boring videos on similar topics. Your right it just takes a brief time to get used to understanding certain words along with the accent (as im not American) Keep up the good work. Your videos are fascinating.

[@smithnjefferson]

I just discovered and started enjoying your channel today falling upon your explorations of questions about genetic tailoring because I am very interested in genetic engineering as shown in the sci fi series “Lexx”, to me growing machines tailored from bugs that can live on garbage makes a lot of sense. As far as your speech impediment goes, I appreciate your humour, Hawking’s voice never made no difference to the information that fuelled imaginations and challenged intellect. Power on

[@danielhall6354]

thanks for including metric measurements

[@ultimoguerreiro82]

I´ve listened to this video half a dozen times. Here we go again. Wish I could "like" it more times.

[@b-man2961]

When I was about 15 or 16 YO, a friend of mine and I used Zinc Dust and Gama Sulphur as a propellant. We achieved significant thrust by using Soda Syphon Sparklets, as both storage and thrust chamber. I did use a cigar tube for a ground vehicle, and only had the Axels and wheels after its run, which was fast, and cloudy. I've not looked into the technical details of this material, however I also know of, and have not tried another mix, which is likewise a Metal and Sulphur Oxidiser, which I've been told is more powerful, this was all occurring back as Man was preparing to land on the Moon, and the Zinc Sulphur mix, produced very well shaped Mushroom Clouds of about 6 to 8 Foot, and a lot of heat at the detonation site out to a radius of about a foot, enough to flash burn off several layers of skin, from my left hand, a friends Mother used cold milk to treat the burn, as I didn't want my mother to know about it. I am unsure as to the effectiveness of my subterfuge, but still have an interest in the fuel as it was significantly more powerful than the Black Powder, I made and used in one of my rockets, which made a nice farrow in the Sand, in Western Australia, Ignition problems :-)

[@stephenadams9711]

I have never had a problem understanding you, and it seems to be getting better.

[@SamEst1986]

Hi Isaac, finding your video's has been an absolute joy, the manner in which you deconstruct complex idea's and concepts is fantastic. Please keep making video's! Cheers, Sam

[@isaacarthurSFIA]

Thank you Sam!

[@brianw612]

Your speech is fine, and you are very through in your presentation. I enjoy your videos.

[@ponyote]

I have absolutely no issue with your rhoticism. Thanks for making such amazing content!

[@tentons123]

I could listen to you talk all day. New favorite channel!

[@isaacarthurSFIA]

Thanks! These day there's enough episodes that is actually possible :)

[@Luke..luke..luke..]

I have never had a difficulty understanding your narration btw. You are very easy to understand even to a posh British chap ♥️

[@brianbrewster6532]

Isaac ... we need more intelligent people in this universe that selflessly and generously devote their spare time to explaining those esoteric material that, without adequate visuals, would otherwise escape our fundamental grasp. Keep up the good work, sir!

[@isaacarthurSFIA]

Thanks Brian, I think we'll see an uptick in this style of presentation as more folks get more comfortable with doing it, hopefully these vids will encourage some others to try their hand at it.

[@brianbrewster6532]

Isaac. Thanks for getting back to me, and again, keep up the good work. We can never have enough people dumbing down science so regular folks might understand these complex systems or concepts. Say, I have a 90-page book, treatise actually, on a way to reverse global warming. Do you have an email address I may write to you about this? I really need a scientific-minded person to critique this work before submitting this to a scientific entity of sorts. Thanks in advance.

[@isaacarthurSFIA]

Thanks Brian! Easier to send it to me via FB, I don't really give me email out here :) I should note that I have a big backlog of material people have sent me, fiction and non-fiction, so you're welcome to send it but I have no idea if or when I'll get a chance to look it over, weeks at least though, sorry

[@urbanstein69]

This is a subject that I have had a deep interest since back in high school, around 1971.

[@10esseeTony]

My Good Sir, as an Uncle of, and friend/co-worker of speech impaired persons, THANK YOU for not letting that slow you down. Keep up the good work, and happy New Year for 2019!!!!

[@parrishmunro8664]

Great episode. First time watcher and I loved this. I'm going to subscribe. This was so enjoyable. Thank you for the excellent job.

[@rbilleaud]

This might be a good time to mention I have a book about space exploration by Arthur C. Clarke written in 1950. It's fun to go back and read some of his predictions, and misapprehensions, about space travel. In many ways, it turns out his view of the state of space travel today was wildly optimistic. He speaks of huge space stations to expedite travel all over the solar system and elaborate bases on the Moon and Mars. In other cases it was surprisingly accurate - and remember this was before the first satellite, Sputnik I was even launched.