Neil deGrasse Tyson Explains the Rocket Equation

[@Yaroslav_Tselovanskyi]

Neil: Have you ever wondered why... Me: Most likely no, but please continue!

[@glenncastro1922]

😂😂😂😂😂😂

[@Doginthesleep]

“I didn’t feel safe doing this but it was for science” 😅

[@TrickyClaw]

Basically every scientist ever lol

[@lipsterman1]

@@grandelDR I guess it's better than "Hold my beer."

[@quasarkid3124]

NASA in a nutshell

[@johnthaxton9235]

😆 as a truck driver I have to disapprove of this message. Please don't.

[@EvenTheDogAgrees]

@@TrickyClaw Basically every _teenager_ ever.

[@mohammedshaik9647]

Startalk just makes my evening better

[@dierandomdie]

Yes

[@LaurenAllport]

My daily space dose.. SORTED 👍

[@_ruted]

daily?

[@drifting202020]

methinks you may be a brit :)

[@barrybenkendorf672]

"I didn't feel safe doing this, but it was for science." ~ Neil DeGrasse Tyson. Greatest statement ever made of all humankind.

[@firefly4f4]

If he was doing it for science, he wouldn't be getting his explanation so wrong.

[@rahulgosavi7682]

About 500 years from now, someone refuelling their spacecraft and "needing a candy" from the shop on an outstation on the moon is going to be looking at this video and saying look how Sir Neil DeGrasse Tyson and people of 21st century thought space fuel stops were a joke.

[@godfreyaweror9850]

That would be hilarious hahaha.

[@freudsigmund72]

and you think humanity can survive that long?

[@PoplarForest]

Plenty of oxygen and hydrogen on the moon.

[@quasarkid3124]

Is Neil DeGrasse Tyson nighted?

[@SavageDarknessGames]

I’ll be eating with them at monolith burger (the Mc ds of space).

[@cdotcizzle6268]

“Did you also calculate how to draft trucks?” “I did that once.” “OH COME ON!” 😂😂😂

[@rakshitbakshi411]

For Science 😂

[@nextuplevelup4119]

Cc ccshow aaaaaa

[@tyrellchibvongodze3566]

Only Sir NDT can say that LOL! When you do what you love, you will never work again. Instead you will fool around dangerously ... for science!

[@kushmandey6880]

Chuck: I wish NASA talks like that.

[@zero11010]

9:02 “talked” ... because Chuck speaks English really well.

[@lisarice9337]

@Ojas I see what you did there.

[@thomaslane1547]

See, I'd have said it TWICE.

[@anmolanand1213]

@Ojas Here's a glass of bear with ICE .

[@MrReneKonig]

"The Rocket Equation: It´s a beautiful thing."~Chris Hadfield Ofcourse I get that ad right before the video xD

[@ikitclaw7146]

mine started with neils ad then ended with chris' ad lol targeted advertising is starting to work!

[@kushmandey6880]

2:44 The happiness of learning science and mathematics.

[@wholegraintoast434]

"Now I need my fuel to get my fuel to get my fuel to get my stuff to the moon" -Chuck

[@jeruakel]

🐐 sh**

[@kostas2047]

ΔV = c*ln(Min/Mfin) , where Min is the initial mass and Mfin is the final mass, this is the Tsiolkovsky equation aka the rocket equation

[@carultch]

@@HopDavid The exponential component of this equation is that fuel mass is an exponential function of the changes in velocity of the maneuvers you intend to make. Fuel mass is proportional to payload mass.

[@kevinfitts9252]

@@HopDavid Is this making you feel better about yourself?

[@adityaagarwal2341]

@@kevinfitts9252 eggsacly...

[@xdragon2k]

What's c?

[@kostas2047]

@@xdragon2k its the exit velocity

[@SteveDeHaven]

I don't know how much Chuck is just playing along, being an intentional sounding board for Neil, but I love the premise of their interaction: Neil helps Chuck see scientific concepts in an everyday way, and Chuck helps Neil see them in a humorous way.

[@mrsdje3425]

If someone had explained this to me 45 years ago the way you two just did, I'd have majored in Mathematics instead of switching to History after failing (three semesters of attempts) to understand the "why" of calculus. I appreciate you guys SO MUCH!

[@lohengramm7798]

@@HopDavid I'm curious about what parts of the rocket equation he botched. care to tell?

[@lohengramm7798]

@@HopDavid I see, very interesting stuff.

[@nyc220guy]

"completely" botched the rocket equation.. please, explain?I see you spamming this everywhere. Inform us of your thoughts that pertains to Dr Tyson "botching" the equation.

[@abdullahibrahim9756]

Always there to fill the gaps in my knowledge 📕

[@alexanderarberg]

​@@HopDavid I'm currently writing a big project about the space race and the math/physics behind the development of the Rockets. Why do you say Neil explained it wrong? And can you go from Newtons laws to get the rocket equation?

[@InsaneMetalSoldier]

This episode should have been one hour long and have Q&A -_- Please do that! I still want to know mooooooooooore about rockets!

[@susanjimenez5500]

You guys are hysterical and educational! Love you guys!

[@harsimranbansal5355]

“Those of you still using internal combustion engines” thats him flexing his Tesla model X.

[@peadrianlastname]

250 miles for 22 dollars on average isnt better than gas during a Republican presidency, you cant work on the car yourself because of expensive specialty tools and parts, diminishing range for about a decade until your battery wont hold a charge and needs to be replaced at a significant cost, and unless you only source energy from your own solar panel the electricity is still most likely produced using fossil fuels thereby negating any positive environmental impact. How is it a flex again?

[@bishalneupane5440]

Here is how we derive the Rocket equation, Neil... From Newton's law, the thurst of the rocket during take-off is given by, F= dp/dt = m (dv/dt) + v (dm/dt) For rocket v~ exhaust velocity, Since, there is no change in momentum, before and after take off, dp=0 this implies, F= 0 m dv + vₑ dm = 0 dv = - vₑ (dm/m) For 1st stage of flight, on integration, v₁ = -vₑ ln (m₁) ...1 Similarly for second stage of flight v₂ = -vₑ ln (m₂) ...2 From 1 and 2 v₂ - v₁ = vₑ ln( m₂/m₁ ) v₂ = v₁ + vₑ ln (m₂/m₁) If, β is the rate at which the fuels burns, m₂ = m₁ + βt Then, v₂ = v₁ + vₑ ln (1 + βt/m₁) This is the rocket equation, It was first derived by a Russian physicist, Tsiolvysky and in his honor, it is named Tsiolvysky's rocket equation.

[@bishalneupane5440]

I apologize for error, there is m₂ = m₁ - βt Then, v₂ = v₁ + vₑ ln (1 - βt/m₁) .

[@milkshakeflake]

Yes I'm so glad to hear Neil talk about having a half full tank for better fuel economy... I thought I was the only one that did that...

[@Arandomguyat1]

Best youtube channel in the world

[@henryshingalili4181]

The animation on the water tower video was very helpful. why did you fire that guy?

[@stevenwoodward5923]

Some people say "why spend money on N.A.S.A" ? without N.A.S.A a lot of electronic we take for granted today would not exist. This is why we need to continue space exploration, for new innovations.

[@NeroThacher]

Random Peoples: "Why would SpaceX put a car into space, thats makes no sense" Me Internally: 'But...Conclusively... You KnOw weve been to space now...'

[@mondariel]

Musk changed standard dead weight for his car. It could be just blocks of weight. Boring

[@billmason9299]

Very True. Stuff..

[@alwysrite]

wasn't that a "test" payload? and he used it to advertise the Tesla - 2 birds one stone? probably claimed advertising costs as tax rebate!!

[@bandofando6898]

@@alwysrite yes I think it was a test but I have to look into it

[@mondariel]

@@alwysrite he is clever. ;)

[@minhho-sd1ig]

You always explain in such an informative way, Dr. Tyson. I love how you love science so much. It’s obvious in all of your projects. I love science as much as I love art because I studied fine art in college. I would love to hear you explain fine art and contemporary art. That would help a lot of art students out because art has so many abstract questions like the questions of physics, like are we living in a simulation.

[@swooshpilot4235]

I love how Neil brings science to the people. This guy is a national treasure

[@swooshpilot4235]

@@HopDavid You are very confused.

[@silmarian]

Staging also lets you optimize your engine for the altitude range it's used in. Different engine bells work better at, say, sea level in Florida than at 80 or 100km in altitude. The less air pressure there is, the larger a bell is needed to extract the maximum energy from the rocket exhaust.

[@leandrocatarci5509]

Cool of you to just drop a random interesting fact like this.

[@matthewl9836]

Please dont draft off 18 wheelers, we know you're there, its dangerous.say yes to life.

[@E2O10]

You're*. But i agree with the sentiment.

[@BhojinderpalSingh]

Agreed... Stay safe...

[@steve-o6413]

Tailgating reduces reaction time calculate that next time you want to save a few bucks, but now I know how they estimate the outrageous gas mileage on New Cars...

[@carultch]

@@steve-o6413 "Tailgating reduces reaction time". I think your words didn't come out right. I think you meant to say, tailgating reduces your room for error, that you need because of your reaction time. Your reaction time depends on the capabilities of your nervous system, not whether you are tailgating or not.

[@Fiction_Beast]

Brilliant! Next video, how tall trees carry water to their leaves, 50 metres up against gravity.

[@isatousarr7044]

The rocket equation, also known as the Tsiolkovsky rocket equation, is a fundamental principle in astronautics that describes the motion of a rocket in terms of its velocity change, effective exhaust velocity, and the initial and final mass of the rocket and respectively. It elegantly captures the trade-offs between fuel efficiency, payload capacity, and the propulsion system, highlighting how the rocket's velocity changes as it consumes fuel. The equation underscores the importance of the exhaust velocity and the exponential nature of fuel consumption, explaining why increasing a rocket's velocity requires a disproportionately large amount of fuel. This principle has significant implications for the design and operation of space missions, where optimizing fuel usage is crucial for achieving desired trajectories and reducing costs. Given the advancements in propulsion technologies and alternative fuel sources, how might future innovations reshape our understanding and application of the rocket equation in space exploration?

[@rozzgrey801]

Fun show, but a bit of a shame you missed the opportunity to say what the rocket equation itself is or the genius who first formulated it, Konstantin Tsiolkovsky, on 10 May 1897.

[@lordonad]

My favorite rocket 🚀 is the Saturn V, love hearing anything and everything about it.

[@migalotto1283]

Im NOT an Astrophysicist but thanks for the great videos.The best way of learning so amazing facts and physics

[@ScienceCommunicator2001]

Wanna become an astrophysicist? It's one of the best decisions you'll ever make!

[@freudsigmund72]

... and now I'm just wondering if there is a video where someone explains the actual rocket equasion. How the calculus in it works...

[@danielluksha2298]

Saw the title, got intrigued, now gotta learn it))

[@carultch]

This is the calculus behind the rocket equation. It has to do with integrating 1/M dM, where M is the instantaneous mass at any given instant, which gives you natural logarithm. You evaluate it from initial mass m0 to final mass m, to find change in velocity as a function of the propellant speed and mass ratio. hyperphysics.phy-astr.gsu.edu/hbase/rocket2.html#c2 Given either free space, or the approximation of uniform gravity close to a planet's surface, you don't really need Calculus to use the equation. Calculus is used in its derivation, but it is already done for you.

[@thomasmogensen1]

Me too..

[@carultch]

@@HopDavid Wouldn't be the first time he gave incorrect information. When he was making an example of how your weight varies as a function of location on Earth, he told Chuck that he'd be 5 pounds lighter at the equator. 5 pounds is unrealistic, unless you are the heavyweight champion of the world record. It is less than a pound for most people.

[@carultch]

@@HopDavid You are correct that there are factors working in your favor for more massive rockets. The factors that work in your favor for more massive rockets, are not because of the fundamentals of the rocket equation. It is either due to the practicality of construction where you get more economy of scale out of the empty mass to payload ratio, or due to air drag becoming disproportionately less per unit mass. Fuel is proportional to non-fuel-mass in the fundamentals of the working principals of a rocket. The exponential function, is a function of the deltaV related to the cumulative maneuvers.

[@cert4]

Best duo ever! Catching up on the episodes.

[@jerzeyguy71]

chuck is Neil's Ed to Johnny, Paul to Dave, Geoff to Craig. love the match up!!

[@Chris_Rybowski]

"I didn't feel safe doing it, but it was for SCIENCE!"

[@JulesCalalang]

I love you guys! you make learning science fun amd easy to understand. Been watching a lot of your explainer zones.

[@rubencolvill]

Man, I love science. I really want to be a theoretical physicist some day

[@racrgrrrl]

Comedic relief aside, at what point did Neil actually EXPLAIN the rocket equation...like, at all? In no reference to the title of this episode, did he once even mention, let alone go over the equation, nor did he attempt to break it down to explain THE ROCKET EQUATION. Is stating the obvious that it takes more fuel to to propel more weight suffice to "explain the rocket equation" as the title states? I LOVE Neil with a passion that cannot be described and his ability to make complex astrophysics concepts relatable, approachable and comprehensible is inspiring generations, future and present much like Carl Sagan has. Star Talk used to be this wonderous playground where you learned things you never knew to question, almost effortlessly. Over the years, I have noticed a steady decline of actual content value, paralleled with the superfluous side jokes and it really takes from ones ability to actually gain knowledge, which I assume is supposed to be the objective of the show. And this episode is a perfect example of that. Mostly complete chatter and in the last 30 seconds or so, he managed to squeeze in a blank statement that it takes calculus to launch rockets. The End. Save us like you once did Neil and transport us back to the times where Star Talk involved answering actual questions in the title. Not Chuck forcing sterile jokes that just simply run dry and derails the opportunity for learning and actually exploring new ideas from the wonderful mind of Neil. Neil, you are a national treasure and should be protected at all costs. But please, if you're going to claim to explain something, please do! That"s what we all come for!!

[@AngryAmphibian]

And his explanation is wrong. Rocket fuel goes exponentially with delta V, not payload mass.

[@knuckles1006]

Sorry Neil, but Wernher Von Braun at first insisted on using a massive single stage rocket to get to the moon. It was another engineer who over time convinced Wernher that a 3-stage rocket was the most efficient way to get to the moon.

[@MonteCristoKaramazov]

These guys are hilarious. I wise Neil was my science teacher

[@donaldsmith8648]

And Chuck was a classmate

[@quasarkid3124]

Chuck is the class clown and Neil is the cool science teacher

[@wzdew]

Neil is a science teacher for all of us bruh. :o

[@quasarkid3124]

@@HopDavid Neil isn't teaching a science lecture, rather he is trying spark curiosity and intellectual hunger in those who are not already scientifically savvy. Even though you are right about Fuel Mass going up exponentially by delta v, there was no reason to be elitist about it.

[@quasarkid3124]

@@HopDavid Neil inspires enough curiosity to make people aware of a specific scientific subject in which they want to learn more. I do not know in what way Neil creates a feeling of superiority, as I watch most of his podcasts and interviews. Also, his support for IFLS is not supporting the misinformation among the blog, rather his objective is to create a curiosity for science as previously mentioned.

[@KimboKG14]

once I finished coding my system of growing flowers just like nature does. I felt like I finally understood the world as it is. Math! So I went on to make a water simulation.... there's nothing more beautiful than describing nature in mathematical terms.

[@mateomiranda848]

This is where the hours playing kerbal space program finally kick in

[@emmanuelesrael6480]

Finally a thing that I can be proud with😂

[@Kudjaks]

Neil saying Mun at 4:24

[@morningeml8176]

Another benefit of staging rockets is that you get to change the rocket nozzle. As you rise in the atmosphere, the optimal shape of the nozzle is different. So being able to time your stages to have the nozzle optimized for your set elevation is a huge benefit. The efficiency of the rocket is related to the geometry of the nozzle which in turn reduces the fuel needed thus reducing cost.

[@E2O10]

Hm, interesting point. Didn't even think of it. Though it makes total sense. Hopefully they will cover this aspect of it in a future video as well.

[@witchdoctor6502]

This was the first star talk where I haven't learned anything new... I don't know if I should be disappointed or proud

[@MusikCassette]

5:35 There is a mistake there. the amount of fuel you need doesn't grow exponentially to the payload. I grows exponentially to the Delta V. It grows just linear to the payload.

[@Nik_TheAstronaut]

Yup,finally someone notices it

[@samarnold1839]

I loved this episode so much. Maybe I am biased since I work in the field, but the 2 of you killed it with this one! Loved every moment.

[@firefly4f4]

If you work in the field, then how did you not notice that his explanation - fuel increases exponentially with payload mass - is wrong? Fuel per payload mass is relatively linear, and actually gets slightly better for larger rockets as there's less fuel tank mass per volume of fuel. Where the exponential comes in is how quickly you want to change the velocity of that payload. The more quickly you need to change the velocity of that payload, the more fuel is needed. The issue with Apollo and Artemis, and why those rockets are so large, is that the payload will do inconvenient things like die if they run out of air, food, and water, get too much radiation exposure, etc, so they need to get to their destination as quickly as possible, necessitating a huge rocket with exponential levels of fuel to get them there quickly. If, on the other hand you have something like Capstone, where there's less time pressure to get to the moon. you can do multiple smaller velocity changes spread out over a few months and use a lot less fuel, thus a much smaller rocket (Electron) can do the job. It's also why rockets use stages. Essentially a large rocket is used to get a smaller rockets up to a certain velocity, then that smaller rocket adds more velocity to its payload, making the change in velocity a function of addition of multiple exponentials as opposed to a single exponential to get the same ultimate payload velocity.

[@samarnold1839]

@firefly4f4 cool story bro. You missed a few things. Remember who the demograph this is aimed at. He made a comment, brushing the surface, and ommited a few implied words, which if you're born speaking English you'd pick up instantly, as it's common tongue. If you wanted him to explain to detail, then this wasn't the episode for you. Thanks for the internet flex. Humble yourself a bit. There's more forces at play than you clearly notice, and your expectations are wack. If YOU worked in the industry, you'd know that payload is only a small portion of the industry, which I do not work in payload.

[@donnahaynes8766]

7:08 "There's nothing engineers like better then constraints." NO! As an HVAC design engineer, I got so annoyed at architects who CHANGED the constraints AFTER my beautiful design was nearly complete! Chuck had it right!!!

[@barbaralachance5836]

You guys are hilarious 😂 😍 I'm never getting fed-up of Startalk

[@Starlightlive]

Chuck Nice should be on national TV, he's a great personality. I'm a big fan and predict he will become a star in the upcoming years. ✨️

[@MultiCyclone1]

Without star talk episode, no sleep

[@TheShizzo]

I don't think it's noticed how quick witted Chuck Nice is. He's quick with funny comebacks, keep it up bro.

[@danebeck7900]

People notice... Dude is hilarious!

[@melanisticjaguar6374]

Not enough people watched this. Great explanation, this video can help young ones be more interested in STEM subjects and their usefulness in modern society.

[@cms1381]

You were so taken by Phil singing while playing drums. Check out Clevon Little from The Band. Yes, the name of the group is, The Band. Story behind that you'll like.

[@MeelaudBoozary]

Damn, Chuck and Tyson are a perfect combo

[@dhruvyadav9499]

Man... I don't know who is smarter.. Neil with his infinite knowledge of the cosmos or the humble Chuck who manages to understand and elaborate every single thing Neil throws at him, whilst maintaining a great comic ingenuity

[@skbar3204]

No one got infinite knowledge 🥴

[@alexanderarberg]

@@HopDavid In my project about the spacerace, my teacher wants me to answer this question: "You are required to account for the conservation of momentum and, based on this, derive a differential equation that can model a rocket's motion through a homogeneous gravitational field." However, I have little to no knowledge of how to derive differential equations. I'm thinking I need to use Newtons 2. and 3. law, and the conservation of momentum law, but I'm pretty lost here. Do you understand rocket science and differential equations?

[@caigner]

You guys are hilarious! Thanks for educating us and making us laugh at the same time.

[@kathryntate6809]

Star Talk is sooo great!!

[@bluemonkey1886]

About the simulation argument, math is something we created. It is a way of modeling, describing, and understanding nature. Math exists only as a human construct to help us do things in the world. The world works how it does and we keep refining math and science to more and more closely model that, not the other way around.

[@lisarice9337]

Please do a segment on the science behind the truck draft.

[@galaxyalexanderh5737]

Y'all literally bring pure joy into my life. Haha so cheese but so true!!

[@abelmedina-aispuro3716]

You both make a great team. Thank you for what you both do

[@H3.5phantom]

I’m very bad with math but this truly drew interest from me

[@eldersprig]

"Architects hate engineers. " That statement explains Bucky Fuller (who was both) so much. And how much does the house weigh?

[@creightonfreeman8059]

"A convenient store in space".....I think that's called a space station. Someone joked that Captain Sisco of Star Trek DS9 was the captain of an intergalactic gas station, but actually Chuck's analogy to a convenient store is more apt. What we really need is to not be using chemical combustion propulsion for spacecraft. Light sails, fusion or antimatter are needed, but even a fission powered plasma/ion drive is a vast improvement over chemical combustion. At least you don't need to carry an oxidizer in addition to the propellant and many of the gases that can be used as propellant are available in space.

[@javierdelapaz8365]

Petition for Neil to narrate all rocket launches

[@drewdrops-6754]

Love this channel so freaking much!

[@stephen3164]

Re: drafting on the highway. I can completely confirm this works incredibly well, and is also severely dangerous without additional technology. Drafting 18 wheelers right off their back bumper - you barely had to touch the gas pedal! Then again, you had no reaction time if they ever had to stop. Luckily they don’t stop short and typically drive pretty smoothly. Unfortunately, they also kick rocks through your windshield really easily, or pieces of their retreaded tire. It’s a scary place to get 100mpg. You’re basically driving behind a moving wall - and there’s no wind. It’s a weird feeling - and not recommended, yet. I think the future of highway fuel economy is in drafting. Link up the cars so they speak to each other. The car in back can get right on the bumper of the first car. The driver in front slows or hots their brakes, and a signal is sent to the car behind to slow down in unison, not in reaction. You could form “car trains” getting great mpg. Self driving cars could make this happen. It works well with normal cars drafting. I had a friend tailgate me for 200 miles, at a decent speed (80+ mph) on a road trip. Their thirsty performance car got near 40mpg! It typically got 16 city, 25 highway, and closer to 20mpg at those speeds. Science!

[@prajeeshjayapal]

Hi Mr. Tyson, please review the science behind sci-fi series "the expanse". Heard it is one of the most scientifically accurate shows out there.

[@JoeLeonardo]

Chuck fake laughing at that Seinfeld joke gave me life.

[@hugoarcada]

I love this 2 guys! Saludos from Argentina.

[@schwibz]

Saludos from Canada!

[@unknown01q2]

Saludos from earth

[@martinsmith1395]

Loved this amusing and light hearted chat. Surprised that, at no point, did you even see the need to show the aforementioned equation…

[@frankjohnson123]

If he had shown it, we would have immediately seen his explanation was totally wrong.

[@kpourhamidi]

Neil being this high for a video makes him so much more relatable!

[@JasonWW2000]

Not a funny joke, sir.

[@kpourhamidi]

Agree to disagree

[@JasonWW2000]

@@kpourhamidi If you want to be insulting to Neil, then just insult him.

[@kpourhamidi]

@@JasonWW2000 how is that an insult?

[@emreaka3965]

That's why i tried to build fuel station in world's orbit when i play kerbal space program. HAHA!

[@akashverma5756]

Every country need one Neil de gre Tyson for generate scientific interests among citizen.

[@AngryAmphibian]

If Neil generated an actual interest his fans would notice he gets a lot of stuff wrong. For example this explanation of the rocket equation is completely wrong. It leaves me wondering how Neil got past Physics 101.

[@barretthenderson5808]

Are you guys able to enable closed captioning?

[@peppeddu]

FYI Von Braun initially wanted to land on the moon in a giant single-stage rocket that it would have to be refueled once in orbit. It was a young engineer at NASA that proposed discarding the unused pieces, hence the multi-stage rocket, that Von Braun initially rejected.

[@stevenvanhulle7242]

Fuel consumption when *driving at a constant speed* depends mostly on air resistance, and friction of the engine, transmission and tyres on the road. The car's mass has only a small part in it (it slightly increases friction, but not air resistance or engine friction, for instance). The mass comes into play, however, each time the car accelerates.

[@fromnorway643]

....or drives *_uphill._* One fundamental difference between space travel and travelling inside the Earth's atmosphere (whether by air, on the ground or on water) is that the former only uses energy to _change_ velocity while the latter uses energy to overcome friction even when the velocity is constant.

[@tkolkebeck]

Loved this dialogue!!

[@Vishalsingh-xy8en]

Alot of love from India

[@StefanHendriks]

Neil talking about re-usable rockets and scale of economics.. And Thunderf00t busting that very concept. How interesting! :)

[@Tony-dp1rl]

In reality, the fuel issue is a lot more complex than they suggest, but this is an excellent video! i.e. if you think about it, you are not sending all the fuel to space, it is being burned off as you rise, so it is a changing amount of mass too.

[@andreisrr]

AFAIK the weight ratio of the tank&fuel assembly vs. the empty tank is also a big engineering challenge, for efficiency. Also AFAIK the bee made honeycomb has the best tank+content/tank ratio.

[@marcusosland-rong3036]

When u are on the space K-mart u are not getting chips and juice, u are getting SPACECHIPS and juice 🥤 🚀

[@sonicsuns]

5:40 "the amount of fuel you need okay to deliver a certain payload grows exponentially ... for every extra pound of payload" . That's not actually true, is it? It seems like it should be exponential, since you need fuel to carry your fuel to carry your fuel, but the fact is that the fuel self-carrying is already factored in. Imagine we have a 1-kilogram payload lifted by 10 kilograms of fuel. However much speed that fuel gets us, let's assume that's the speed we're aiming for. Now we increase the payload to 2 kilograms while the desired speed remains the same. How much fuel do we need now? That's easy: 20 kilograms. In both cases the fuel is delivering a payload that's 10% of its own mass. So the amount of fuel we need doesn't go up exponentially; it goes up linearly! This becomes clear when you realize that you could just as easily split the 2-kilogram payload into two separate rockets. In our example a 1-kilo payload gets lifted by 10-kilos of fuel, so obviously if we have 2 rockets at 1 kilo apiece, each rocket would need 10 kilos of fuel, which is 20 kilos total (split between two rockets). Delta-v is the only exponential part of this. Fuel requirements don't go up exponentially with payload. Neil should have known better.

[@AngryAmphibian]

I'm happy to see more people noticing Neil's explanation is wrong.

[@entropie-3622]

5:35 That seems incorrect to me, the amount of fuel should grow linearly with the payload (Simple thought experiment: to double the payload you can just cobble together two identical rockets which will only double the fuel requirement).

[@E2O10]

It's exponential, if i'm not mistaken. Since every kg of payload requires a certain amount of fuel, every extra kg requires that same amount of fuel + the fuel needed to get that extra bit of fuel into space. In other words, (and to make it more clear let's say 1 kg requires 1 liter of fuel) if you have a 10 kg payload, it requires 10 liters of fuel. If you then add 1 more kg of payload you'll need 1 more liter of fuel plus a little extra because the 1 more liter of fuel also weighs 1kg (which would require a whole extra liter to get up there, and so on and so on ad infinitum). That's exponential growth. Excuse me if it's all gibberish. I have only studied maths/physics in my native language so something obvious may be lost in the translation for me, but i think what i said is essentially correct.

[@ASJC27]

The rocket equation is about how much fuel is needed to gain some speed, and that mass ratio grows exponentially with required speed. Getting to a higher (further) orbit requires more speed, so getting a given payload to a higher orbit is also exponentially dependent. For example, Earth's LEO speed is about 8 km/s; If we have a one stage rocket with a specific impulse of 250 sec, and need a launch speed of 12 km/s (1.5x) to get to some other orbit/trajectory, that requires a starting weight not 1.5x higher, but 5x higher [exp(8,000*(1.5-1)/250/9.81)].

[@entropie-3622]

@@ASJC27 Yes, I suspect that that was the point Neil intended to make, but for whatever reason instead of saying the amount of fuel needed increases exponentially for every extra amount of speed (or distance from earth) he said "for every extra pound of payload".

[@steve-o6413]

If we're ever going to get serious about Space we need to get rid of the Fuel Tank and come up with a better solution, like a Rail Launcher or Mag Lift. Fuel Tanks are so 60's...

[@E2O10]

@@HopDavid Alright, fair enough. Thanks!

[@mariobernard5583]

"We need fueling stations in space" - The rationale for in-flight refueling of military aircraft is similar. Aircraft, say, like, bombers, can take off with more weight than they can land with (hence dumping fuel for an unscheduled landing). Cool. But aircraft can also *fly with more weight* than they can take off with. So take-off with enough gas to make it to the (airborne) fueling station, then fill up to max in-flight weight. Bonus points for saving gas due to taking off lighter than max take-off weight, and starting the actual trip with a full gas tank.

[@desecrationfly]

I’d love to know if Neil has ever heard of ‘Kerbal Space Program’, a game of physics, rocket building and orbital mechanics. It’s so fun and really gives you such a great understanding of all the physics we don’t get to see visualised and concepts like delta-v TWR and the trajectory’s of ships n how they make orbit. It would be amazing content to see Chuck trying to figure it all out with Niel coaching him!

[@firefly4f4]

If he had, maybe Neil wouldn't have botched this explanation of the equation so badly. Fuel required increases LINEARLY with payload mass, not exponentially. Where the exponential comes into play is how quickly the payload needs to reach the needed velocity. Less time requires exponential more fuel. That's why if you don't really care how long it takes, you can use a smaller rocket to get the same payload to the correct orbit. Some payloads, like say people, have limits for how long they can be in a small capsule, so they need to get to their destination (ie final velocity) faster, and hence that's why the rocket is so big.

[@theelephant2887]

Chuck is like "that's funny", "now, that's funny", "ha, that's even more funny"... 🤣

[@thinkethiopia958]

awesome as always from ethiopia

[@JohnDuthie]

Hi Neil and Chuck love the show!

[@adityaprasetiyo6590]

ONE OF BEST EPISODE

[@Kudjaks]

Neil did say Mun at 4:24 and i dont care if its true or not, Neil playing KSP is canon for me now.

[@1mezion]

I'll said it before. If there was a Neil in every school from kindergarten go up we would have intergalactic space travel by now

[@levyy_012]

These two make me proud ❤️

[@AnthonyDDean]

NASA alumni here - love it!

[@vanessascully4444]

I'd like to see a video explaining the high concentrations of Xe 129 on Mars. Please?! Here's Vanessa from Brazil! Big fan!

[@ChadTheHow]

They say when you're laughing, you're learning and I definitely learned a thing or two about rockets on this video. =D

[@ricaard]

They are genuinely having fun sorting out the math together.