It's really sad that Scott has to take time to answer this. And no, it's not sad that the world is such that FE people exist and spout their nonsense. Because I never hear from them, but always hear about them from people who can't stop talking about them, and have given them more energy and popularity than they ever could achieve on their own. All because people are obsessed with a notion that society needs information policing in order to prevent some sort of decay in intelligence and/or prolonged social injustice. You just need to stop talking about some things and they will virtually disappear.
Best quote ever, "If you're a super bad-ass God, you're going to create a universe with 56 billion light-years across, and hundreds of billions of galaxies with and stars in them... you're not going to create a tiny little disk with a dome over it." -- Scott Manley
@@chrismusix5669 That might be okay, if they didn't constantly go out of their way to spread easily *falsafiable* ignorance (as opposed to unfalsafiable faiths...by definition, that's outside of science). It wasn't a word I used before, but yeah, I do condemn determined, contagious ignorance. And who exactly must I be to do so? I'm no teacher, but their profession *exists* for the very purpose of reducing ignorance. Sincere Flatties (as opposed to amateur or professional trolls...check the comments in many NASA.com or Space.com Facebook postings) generally don't have the excuse of being children that are still relatively new to the world, and know little beyond their immediate, personal experience. Flatties insist that that's *all* there can be. Yes, I plead guilty to having zero patience with that, in the face of endless evidence to the contrary.
The question was a bit blurry anyway. Before the landing you have to get there. Between there (moon) and there (Mars) is enormous difference. Could mean days or months in space. Think about big machines that go for months without problems. And not a parking, landing or docking away from having a mechanic checking it out. You better be sure about that. The actual landing is only a tiny part of that. And as he says, with a single stage lander you put all on one card. Potentially 100,000,000 km from home.
They will have to have some sort of launch escape system similar to the crew dragon. I'd imagine they could integrate it into the nose of Starship and have any crew/passengers in that section of the ship during any maneuvers. That way any time they're launching or landing the crew and passengers have some means of survival if Starship fails a landing or has issues during launch.
At some point SpaceX will make it very reliable and then decide to put people on it. People will choose to fly on it. People jump off of cliffs with wingsuits. Sometimes they die.
Landing on the moon is different compared to landing on Mars. You don't need to have a flip manouver, therefore you can start the engines earlier and "test" them. On Mars, you brake with the atmosphere and light the engines for the flip manouver and landing. If there is an issue at this time, it's probably over
The best solution I've seen for space junk is the "bottle deposit" idea: when you launch something into orbit you have to pay a fee, as a deposit against its eventual deorbit. If your satellite fails to deorbit, the deposit is used as a bounty, paid to whoever brings it down. Garbage collection companies can now profitably de-orbit junk for the bounty.
There is already policy in place to require satellites to deorbit or to move to the "graveyard orbit" once they reach the end of their usable life. But I like the concept, it's a good idea.
For the safety issue: different people accept different levels of risk. Hardly any of us would do something that has a 10% chance of killing us, yet lots of people are still climbing Mount Everest every year at those odds.
that's because the people climbing everest think they are good enough it won't happen to them they are arrogant and most of them think their skill is above average :p
Famously Ed White said: "IF we die we want the space program to get on. It's bigger than us." Which given (Apollo 1) history is a chilling and powerful statement. It's hard to imagine a Space Tourist saying that. Or another one buying a ticket after a fatal fail. We also heard "it will be as easy and casual as taking a shuttle on the gorund" before. There is no unsinkable ship and Elon's will be no difference. Promising casual riskless space flight WILL come back to bite you in the arse. People climbing Everest KNOW the risk. Or if they believe somebody that it is easy, they are stupid. While risk is a faint concept from another universe for most SpaceX fans. And Bosses.
@@donsample1002 In the United States, who exactly am I putting at risk by going to the pub? The pub goers are all consenting to be there. Everyone at risk has already been vaccinated.
Thank you for answering my question about throttling and the lower ISP with lower throttle. Also, the little tidbit about the RS-25 being able to throttle down to 10% blew my mind!
Yes, but there is a big chunk in the middle of the throttle range that is not good to stay in long, you transit fast, because there you will have instability.
@@1224chrisng do you mean like trying to land it it like the center section of a Falcon Heavy? At this point it would probably be a bad idea to add a level of complication to the program. You'd definitely have a lot of variables to balance, like, what exactly are the throttling windows, how much mass are you landing, how can you adapt a landing leg solution to the current architecture, and for what cost in mass, and then where does all that put you in terms of flight profiles.
@@1224chrisng ok, that's what I thought at first but then I wrongly assumed you were asking about something much more reasonable. Attempting to retrofit a system like ULA's would most assuredly explode the cost of SLS. It would add maybe less weight than legs, but the complexity would give all the SLS contractors a field day(decade) to implement at absurdly inflated cost.
On a site that sells custom T-shirts? Or just post it into the internets a bit and wait for chinese bots to pick up on it and presto, some will be available in some shitty chinamart.
Listening to Scott explain things is like listening to your favorite uncle explain something complex; very informative with not a hint of condescension. Which in this case, for me, is weird, because I'm probably twenty years older than he is.
It's not an age thing, it's an enjoyment and respect for the subject matter, and wanting to share it with others by coming together. You can see it in Scott's face and hear it in his voice, he thoroughly enjoys it himself and just wants others to feel that way too.
Re: "The Expanse" question: They weren't using the RCS thrusters. They had to use the keel-mounted railgun since it used a separate power supply from the rest of the ship (it's own bank of batteries normally charged by the fusion reactor). On top of that (and I don't recall if the show has this), the Roci was pretty badly damaged from the corporate's light shuttle/bomb getting turned into shrapnel, so several of the RCS thrusters were damaged beyond repair outside of drydock. Because of the shrapnel impacts, and damage to thrusters, they were in a very complex tri-axis spin, and had to time the railgun shots just perfectly to impart the correct direction of thrust on both ships. The rail gun couldn't have fired continuously because of the complex movement, and the fact that it probably would've melted. Finally, they can't "move about... with impunity", they *do* have limited fuel in the form of reaction mass, AKA extremely pure distilled water which they use for potables, coolant, RCS "fuel" (they shoot out steam), and for the Epstein Drive.
Great explanation! Let me just nerd-out about Expanse a little here: In books they actually care about reaction mass a lot, ie 5th book, after high speed chase with Inaros, when signal from Chetzemoka appears, Holden stresses out about Rosi not having enough of mass to turn around and intercept Chetzemoka. That's why Razorback goes there instead, being on more favourable trajectory. And there are more examples like that. Autors have been deliberately vague about workings of Epstein Drive (ED) and show even more so, to not get into shouting matches with space nerds. But that doesn't mean they don't have theory. In books there are ships equiped with fusion reactor, but without ED (not shown in show), that care about reaction mass even more, being able only short runs. That leads me to ED not being just better (stronger, more efficient?) fusion reactor (that is pretty much treated as free energy source, as when they get hands on Rosi, they note she is stocked up by fuel pellets for decades of continuous run) but some other part of propulsion. My theory is ED being converter that allows huge variability of reaction mass insertion, ie you can inject just few molecules of water, concetrate full power of reactor on them, heat them to few millions of K and eject them, therefore reaching truly insane Isp of reaction mass and saving it. Trick is, it is not energy efficient in this mode, but reaction mass efficient, maybe only 1% of energy of reactor is used (energy being free resource, as explained above. Another question is, where the rest of energy go? "Magic!") and raising Isp thousand-fold. This is used in low G burns. Or you can go full throttle, flood ED with reaction mass, get near 100% energy transformation efficiency, much lower Isp out of reaction mass and high G burn. I am yet to find passage in the books incosistent with this, but until authors speak up, we will never know. :)
Guys, seconds ago I found an original newspaper from the 21st July 1969 headlining "The First Men Are On The Moon" under heaps of other stuff my late Dad had stored in the basement! He never told me about it. I was short of two years old back then.
I invoked your name when I saw a post saying something like, 'Why blast your enemies into the sun when it takes significantly less Delta V to launch them clear of the solar system?' I said, "Scott Manley Approves this message"
That gas choke condition explainer was super helpful. Makes a lot of sense that it kicks in after you cross the speed of sound, but I'd never heard anyone explain it that clearly before.
The Expanse has FTL so I'd not expect much. I like the thumbnail letting us all know that the real proof the earth is not flat is that cats would have knocked everything off if it were.
I sorta think this is opportunity to sift the best topics..if many people ask about a particular thing, then he might consider making full length videos ey
@@AbuctingTacos I don't think that would be the case. Tim certainly goes into immense detail with his hour long commentaries on a topic, but Scott has got him beat in breadth and sheer number of topics. These days I see Tim mostly working with live streaming Starship development. I hope he does another deep dive video again. The last one he did was about Starship and that was 5 months ago.
@BullShark He built a studio to provide better coverage of everything happening in Boca Chica and insurance paid for his wrecked tesla. Whoever told you otherwise is lying
Another reason for all kinds of conspiracy theories is that it’s an easy way to find social acceptance. No matter who you are, if you just believe the same strange thing, you immediately get accepted as “one of us”. Being an accepted member of a group is a strong drive for humans, and some need to resort to conspiracy theories to fulfill that need.
It occurs to me about Starship: The sea bottom is littered with the wrecks of wooden ships. Now hundreds of years later losses at sea are all but unheard of. But we never would have gotten here waiting for the Queen Mary to be constructed. We don't need to be completely reckless, but if we're going to get anything done we probably need to be a little more risk-tolerant again.
The only problem with that argument is that there is/was no snowball effect at sea. Yet, if one unlucky satellite blows up just the right way and causes a chain reaction in near earth orbit we might lose alot or all satellites and also might not be able to go to space for a very, very long time. That would be quite catastrophic.
Re flat earth: people like to feel special, and like to feel that they know something others don't know. The trouble is, it takes a lot of time effort and intellectual humility to go and study something and EARN that special knowledge. So instead, they short cut the whole thing by "studying" TH-cam and finding conspiracy theories that take minimal effort to feel convinced and which they know few people will believe. The more others resist, the more they become "sheeple" and the more special the individual feels. It's a circular logic, sure, but that is part of it. Even the logic loop itself gives them an odd kind of security because it reinforces the in-group/out-group dichotomy. Social Media then, with its anonymity and short comment length is an ideal environment because of its lack of accountability and the lack of need to offer evidence or rational argument. Sorry for the long and probably obscure post. For reference, I'm a sociologist and my field is normativity, that is, how people construct their world and apply 'norms' to maintain it.
Have you ever considered doing videos that would tackle this subject in this way? There are so many youtube debunkers that use science, math, and evidence to debunk, but I haven't really seen any that talks about the psychology or sociology behind it. I would love to hear people talk about this topic (and other conspiracies) using this framework!
Thank you for saving me to write that myself. I am not a sociologist or the like, but I encountered some hard conspiracy theorists... I always had the feeling that they just wanted to "know something"
@@PsychoMuffinSDM Actually, I have considered it, I even put all the equipment together and did a few trial runs, but with such an anti-intellectual, anti-social/behavioural science attitude being so prevalent these days, I don't know if it is worth the effort of putting up with the willfully ignorant. The other problem is that the kind of science I do frequently conflicts with political bs and deeply held prejudices that people cling to. Science is of course, based on evidence rather than belief, but it nevertheless, doesn't happen in a social vacuum. I wind up getting so frustrated by dealing with the endless stream of abuse that my partner makes me take regular social media breaks. Thanks for your comment though. I really would love to do something like that and perhaps if I could develop a sense of community where there is a core of people who are genuinely interested in it, I'd revisit it. For what it's worth, I agree with you. Perhaps if we could break this idea that the only true Science is physical science, we could make some progress... Not just on TH-cam but in society in general. I've actually thought about posting some of the classes I used to teach about culture, identity, power, sexuality and world affairs. Would that be interesting to you?
If you havent seen the trailer scott mentioned go watch it, He does a little breakdown on it and its pretty cool. Would not surprise me if spacex or nasa or someone starts testing it irl.
Flexible tethers would be kinda weird in 0g. The tension pulls spacecraft together, but nothing stops the craft from continuing to move to each other and colliding. Maybe solid telescopic rods or long modular structures that'd be built on site would work.
@@emiel2712 I wonder if it would be possible to create a flexible tether that can transmute (think that's the right word) into a more solid one, perhaps with an electric current. I imagine it would be a good idea to make the process reversible or perhaps adjustable as well, a little bit of flexibility could prevent the tether from snapping under load.
Yes, a tether episode would be interesting. A couple of points about the Starship. The atmosphere on Mars is so thin that you would think that the vacuum Raptors would be used for landing but the current design is with three fixed Raptors outside the three movable air Raptors in the center of the rocket. This means using the less efficient air Raptors for landing is necessary. Using only one Raptor for landing is a bit silly since it means a leaning Starship when landing. Two is better but the thrust is still off center. With an empty Starship this seems to be necessary but deep throttling for a three engine balanced vertical landing would be better. Hopefully the improved Raptors Elon has said were coming will allow for deeper throttling and balanced vertical landings.
15:50 if I remember correctly in the book they were using the roci's rail gun which itself needed the ships main thrusters to normally counteract its recoil and firing it normally to their orbit to shift it and buy time not to keep them in orbit indefinitely never seen how the show did that scene though
I'm a Baptist, and attended fundamentalist Baptist churches while growing up. I never heard anyone claim that the Earth was flat, or a flat Earth was required to show the power of God.
@12:30 One big reason for vertical integration is that horizontal integration, especially for long payloads, requires a lot of structure to support the cantilever forces when the payload is horizontal and only supported from one end. A structure that only needs to support its weight vertically can be made much lighter than one that has to cantilever from one end. In this regard there could be some solutions to still integrate horizontally, such as having some temporary external structure supporting the payload that is then removed after the rocket is vertical. However that still imposes a lot more effort on the client. Generally the client (designer/builder of the payload) would rather not have to worry about designing their payload to withstand stresses that it needn't be subjected to.
Sort of. If you look at your copy of the Falcon Users Guide (August 2020) page 16, for loads over 4000lbs the lateral acceleration will be less than +/- 2g. So loads should already take horizontal loading (1g) into account. What, you don't have your Falcon Users Guide on you? I suppose you forgot your towel too... OK, here is one. I'll trade you for a Red Dwarf technical guide :-)
My question: How much of the propellents used to put vehicles into orbit comes back eventually due to gravity, and how much is lost to space forever? Are we creating an erosion problem for some of the rarer stuff, i.e. helium used as a pressurant, and how imminent is it? I really appreciate these viewer questions answered videos. You're under no obligations to continue them of course, but I'd be really jazzed if you did. Thank you Scott!
If you have ever towed another car with a rope or cable, you will likely have experienced another problem with towing in space. Getting rammed by the thing you're towing due to recoil from elasticity of the tow line and the energy lost from imparting it to the towed object slowing you as it accelerates the towed item. On roads, you also have to deal with the problems when the tow vehicle wants to slow or stop, if there is not control over braking in the towed vehicle.
I have a question that, When a rocket flying through air then does it becomes a charged body by friction? If yes then any problem can cause to the rocket and how they discharge it?
I don't know what they do on rockets but on planes they have static discharge wicks on the trailing edges of the wings/tail. I wonder if rockets do something similar?
For vehicles that return to ground instead of splashdown, there is a ground strap that contacts the ground first. You can see it on the legacy shuttle and SNC dream chaser next to the wheels. The soyuz has a conductive spike antenna released with the parachutes.
While the rocket is in its launch phase, the rocket exhaust is conductive so the rocket and exhaust are basically the largest lightning rod ever. Apollo 12 suffered two lightning strikes during its launch, so it can be a problem. Scott Manley has a video on Apollo 12 if search for "SCE to AUX" on his channel.
For the expanse episode, they were using their railgun as a rudimentary thruster, and they could only fire it fast enough to barely maintain their orbit. They also designed a clamping system to absorb the jerkiness of the thrust, and a software program to aim it as accurately as possible to ensure the vectors all balanced out.
I'm outside at a patio table and a cup of coffee. I'm so into the video that my cat jumps up, gets tired of being ignored and pushes my cup off of the edge.
On the expanse scene: They were trying to quickly burn prograde to raise their orbit. Later they continued this by shooting the railgun in retrograde direction, further increasing their speed by the recoil. The ships were so low that they were encountering a lot of air drag. Since they were relying on their fusion drive this would never be a problem. But without those the ships would be slowed down and reenter in a couple of orbits.
whoa! Kerosene + HTP requires no cryogenics. Surely that saves weight, must be more reliable, and helps with logistics (ie, you don't need to fuel immediately before launch). You don't have to worry about weird bubbles in the tanks. Surely all these things are worth a little bit of specific impulse.
Assuming your HTP doesn't blow up. Allegedly like the Kursk or HMS Sidon (I have not verified those stories, they are on Wikipedia). By the time you've diluted it to stability, you've lost some performance.
as a Christian, and a engineer, i view science as a means of showing God's might and intelligence. to me it shows that the more we find (law of physics and such) lends itself to there being a creator that sets and holds these properties in place. as if there was no creator force, what makes these laws happen. as for the person you mentioned, their teacher is horrible misguided at best. there are many wolves in sheep's clothing in our ranks (Christians) that unfortunately don't fully read or comprehend the bible.
@@mcs699 you can't disprove the existence of God, so its not really anti-science. There are plenty of scientists that are Christians. Think about it, if matter cant be created or destroyed, then how did the big bang happen? Something supernatural had to have created the natural universe. God said "let their be light" when creating the universe. The big bang was an exponential expansion of light and matter. God essentially sparked the big bang.
Keep in mind that the bible was written (and collected from older bits) by humans! Tribal humans at that. Everybody can do with the philosophical, moral part of it what they want. Even that need interpretation, as it is often contardicting itself. Which is how Theologists earn their money. But taking it as a literal source for science (whit the carefully sceptical exception of history) was and is stupid. Doing it literally but from a translated version is then completely idiotic. The whole Ararat thing is a good example*. It's probably fair to assume, what these people wanted to convey, wasn't wether the earth is flat or what orbits what. They didn't know and very likeley didn't care about that. * the original version apparently said "among the mountains of ararat". Translations changed it to "Mount Ararat". The one which was swarmed by Ark searchers wasn't even called Mount ararat at biblical times.
@@5Andysalive what parts of the Bible say things that have been disproven by science? If something hasn't been proven nor disproven, then why can't you think thats how something works? Scientists don't know what goes on inside a black hole, so what ever theories they come up with that aren't proven, can't be assumed to be correct, so if something from the Bible says something that hasn't been disproven by science, why not believe it? After all, there's nothing saying that what they said is wrong?
As for the flat earth comments, I'd recommend Carl Sagan's pale blue dot - he talks a lot about geocentrism and imagined self-importance. Incredible writing that I'm sure you've actually already read...
Having just read “Ignition” (thanks for the recommendation) the author asserts that HTP wasn’t used much after the UK space programme ended because when it breaks down it is a run-away reaction (read BANG!) - and the USA and USSR had worked out how to work with RFNA based oxidisers when they needed dense liquid propellants..
"Ignition" by John Clark (now available as a paperback reprint) reads like a Steven King novel for chemists. Noooo, don't even think about ClF3! My mind is exploding vicariously. Sutton: Rocket Propulsion Elements (original copyright 1949,) agrees: "It has not been used for a long time, partly because of its long-term storage stability." (quote from the Seventh Edition, 2001). Although Soyuz uses peroxide, it seems to be the limiting factor in Soyuz stay-time at ISS. Nothing makes me nervous like peroxide. The highest concentration I've ever handled was 35%.
@@hanspecans Thirded! One tether application also ties with the space debris removal because a space tether can be a propellantless method for propulsion. Joseph Carroll's EDDE is one of my favourite concepts - the ElectroDynamic Debris Eliminator. 100 kg, 10 km long, with nets for capture at its ends and a small fleet of them would do the rounds up and down to clear all the old rocket bodies and derelict satellites in under a decade.
For anyone interested, I'm pretty sure the documentary he's talking about at around 11:00 is "In Search of a Flat Earth," by the youtube channel Folding Ideas.
I'm more interested why lots of people assume Flat Earthers believe in God and are religious. I'm a Flat Earther but I don't subscribe to any god or religion. I think that's all BS imo. My personal view is man fabricates his understanding of the natural world and God, the Universe, the planets, Jesus and much much more is all part of that fabrication. In other words man makes it all up using his imagination and in many cases convinces people using contrived demonstrations. So some forms of science is no different to believing in God!!! Welcome to man's fabricated world!!!
@@PeterPete You would be a minority then. Basically flat earthers in general (i.e. not you) take a couple bible accounts literally, and their misinterpretation of it is compounded by bad translation. Its a bit of a read, so skip it if that synopsis is enough: In the creation account, some translators take "circle of the earth" from a word that could easily be sphere, and the vast majority of passages in the bible are written from a humans perspective standing on the earth. Thats why some get confused by things like a bird flies in heaven ( the sky) and a spirit realm. Another passage says the devil showed jesus "all the kingdoms of the earth," and say the earth cant be a sphere because he wouldnt be able to see through the earth. However, they forget the other half of the scripture, and "all their glory " and, "in an instant of time". They also fail to understand that even if the earth was flat, there is no place from which you could see all of it at once. It has to be figurative and not literal, meaning he showed their power, riches, and influence rather then "the earth is flat, here is every kingdom from this huge mountain." The creation account is also taken to mean literal 24 hour days.... despite the fact that the sun is created later in those days so earth "days" didnt even exist yet. Its also a translation issue... a day can mean many different lenghts of time. For example, when was your great grandfathers day? Probably around the 1900's.... but its not a literal day. Its more of an era. There are others too, but I really don't want to write more, and don't want to try to think about them. But essentially, religion is probably the biggest factor in FE.
@@blackdeath4u The bible is a book made by man using his imagination. It is a book filled with metaphors to account for this thing we call 'life'. The bible mentions the firmament separates the waters above from the waters below. Imo nobody can ever come to know that even a firmament exists so this metaphor could relate to a woman's womb during childbirth, afterall the universe is within each and everyone of us - without us there is nothing. Lot's wife turned to a pillar of salt after looking back at the destruction of Sodom is another example. In my understanding this is just a metaphor to compare turning to a pillar of salt to losing one's peace of mind. The image of something really bad can plague one's mind for the rest of their lives. Reminds me of Indiana Jones when he's tied to a pole and the Nazi's open up the Ark and he shouts to the woman to close her eyes, not to look at the spirits, flames, and bolts of energy that kill all who are around them. So there's similar metaphors even in films and probably lots of other outlets too. Lawrence Krauss talks of everything comes from nothing and I can agree with that, afterall, what came before me when I was born was nothing and what will be after I die is nothing and yet I, as an individual am the universe. Quantum entanglement talks of how two people can become entangled during a lifetime, yet I could call that true love. So there are similarities of meaning in religion, film, TV and even in parts of science. It seems, everyone talks about 'life' but they use their own language to reach out to their followers to help them understand it, inadvertently confusing them along the way. It still does not get away from the fact that imo nobody can ever come to know the true nature of reality. Mainstream science stating oxygen is a constituent of the air is in my opinion man's best guess to explain what air is, but there is no oxygen as a constituent of the air because nobody can prove that. Lavoisier just convinced people using his imagination and a few demonmstrations!! If you think I'm wrong you're more than welcome to prove to me there's 21% oxygen in the air!!! Btw, the Earth is a level plane, the globe is merely a construct of man's imagination because men and women dislike the beastiality of life. I can sense another metaphor coming on - Satan, the Devil, the beast only refers to the animalistic nature of human beings. Haha!!! I don't want or need a dream existence!!
"If you haven't watched [The Expanse Season 4] by now, it's a year and a half old..." Me who only just got around to watching it last month: that's fair
@@weatheranddarkness Yeah, fair, though I try to keep art and the artist separate, it's not always that easy. Still, it's worthwhile, especially in this case as it's such a good show
Its feels good to have Scott do Q and A. He is just so thorough and complete in his explanations. So many questions i would love to ask! Also, props for the Maturity in addressing the kinda Religious subject of Flat Earth. Thanks Scott! Looking forward to more Q and A episodes :D
Even if starship is only ever safe enough to carry cargo that is still MASSIVE. the biggest hindrance to opening up space is getting mining equipment, building supplies, food, water, oxygen, etc, etc. To the destination. Even if starship is only used to build big human rated ships and stations in orbit, its still an absolute game changer
I've just finished reading the fourth book of the Expanse and yes, there are some problems with orbital mechanics, like them doing simple burns towards and away from ships to dock or meet instead doing the complex "messing around" that you have to do in KSP for example.
The docking stuff is mostly because in the expanse, they can afford to do that. They have torchships that can burn for months at 1g. The fastest way to get somewhere in a torchship is indeed to point (almost) straight at it, burn till halfway, then flip and burn to decelerate. You cant do that in ksp because we only have fairly wimpy chemical and atomic engines.
@@TheToric I meant the situation when their reactors shut down and they were flying around with their EVA suits. In the TV series it was a bit different and they were flying mostly with their ships, which probably had more delta-V, but in the book they were using nitrogen thrusters in their EVA packs which don't have a large specific impulse.
@@TheToric You also have limited fuel and so to do things as effectively as possible you have to tiptoe from orbit to orbit. Anyway, once your close enough in KSP (km or so) you get away with pointing and flying.
Hi, Scott, thank you for this video. Could you please explain: Why non-reusable rockets are always painted? They would have no time to rust, and paint weights a lot, also, paint on the top stage produces space trash.
That's a *very* good question. I think the early DH Comet jet airliners were polished aluminium to save weight as the first generation engines weren't over blessed with power ....
Reasons I can think of: - Rockets are some sort of status symbols --> always a good opportunity to place a flag on --> flags tend to like a not-shabby surrounding ;-) - Paint somewhat covers the structure --> less easy reverse engineering by just watching - the parts exist long before the launch and in most cases have to be transported --> Paint ensures quality during production - Launch sites tend to be next to shores --> salty air is agressive - Launches tend to be postponed --> rockets have to endure a certain time without any risk of stuctural weakening - Paint might be just not as heavy? I imagine they do not use roll-on wall paint from the store next corner Also: - there are rockets which are mainly not painted (Delta IV, Space-shuttle main tank, some old stainless steel rocket (Atlas ?) )
@@LoneStarr1979 I think stainless is a bit of a bitch to get the paint to adhere. I'm sort of thinking as an anti corrosion protection as aluminium can and will - but in a nice, air conditioned assembly hall followed by a quick trip to the pad and then up I to space ... i wouldn't think that would be a problem... But then, I ain't no rocket scientist.
@@LoneStarr1979 I am Russian, so i better know about russian rockets. We have no launch pads near shores, you can download Soyuz blueprint with all visible parts, parts doesn't exist too long before launch + everything is in hangar before crawling, transporting is fast, it tooks hours, not days. Also, our rockets are not white-blue-red, they are 90% white/ But, any vay, we also paint our rockets
Slight correction. Engines reduce efficiency during throttling because they're being put into a state where the turbomachinery, etc isn't operating at its design point. Turbine airfoils, pump vanes, injector mixing, etc. For nozzle design, it's really just about flow temperature (total temperature). Reducing the chamber pressure doesn't really reduce the exhaust velocity, especially in a vacuum, because once the flow is sonic in the throat, everything that happens after that is really just a function of engine geometry and gas temperature. And the absolute velocity is dependent on the local speed of sound at the throat, which is a function of just gas temp. You'll notice in a vacuum the equation for rocket engine exhaust velocity, the pe/p term goes to zero in a vacuum and therefore you'll note the only variables that matter are T, and the exhaust molecular weight. Also, Bernoulli's only applies to incompressible flow.
@@scottmanley Lots of reasons. As mentioned, injectors are designed to mix most efficiently at a certain jet speed (injector dP). Also depending on engine design, if you utilize film cooling/ face cooling the ratio of that to the core flow will be higher at lower power and since film cooling is combusted less efficiently, you lose performance there as well. If you expected Isp to scale with Pc, you'd expect a linear relationship with Isp and thrust. But in that case you'd expect for example the DPS on apollo to get like 30s of specific impulse at min power, which isn't actually the case. Injector c* is really quite sensitive to mixing
The question about space junk got me thinking. I gather a lot of satellites are quite small. I wonder how many could be captured in the hold of one of the space shuttles if they were on cleanup duty.
Deorbiting will always be a money pit, until companies realize that "junk" in orbit is basically free material, free of launch costs. Be decommissioned modules, satellites, whatever it may be. Notice how I said companies. This will always be a private sector venture, since public space contractors see nothing wrong with saving x by burning up 10x.
It takes more delta-V to significantly change the inclination of a low Earth orbit in space than to land on Earth and launch again. When two objects in different orbits collide, it results in a lot of space junk being sprayed into space. Anything designed to gather space junk will have to closely match the orbit of each piece of to catch it. Sane governments probably won't allow a company to launch something like a giant sponge to intercept junk larger than dust grains. SpaceX has demonstrated that it is possible to launch thousands of satellites as part of one big project. It will eventually be possible to make something that can meet up with junk in a small set of orbits that are very close together in terms of delta V. There is actually a space tug that is boosting a geosynchronous satellite that had a launch issue that left it low on fuel. This space tug can also move dead geosynchronous satellites into a graveyard orbit. The one tug might be able to move 2 or 3 satellites before it moves itself to a graveyard orbit.
Hey Scott, if you do look into tethers more, I highly recommend looking at the Miniature Tether Electrodynamics Experiment (MiTEE)! It's a project from University of Michigan that launched in January on LauncherOne that I worked on in grad school. It's looking into using tethers for propulsion in LEO.
Scott, as always, you are a gem to humanity. In regard to helicopter safety, not all helicopters can autorotate. Also... Jesus nut... Anyway, the ability to autorotate is certainly a backup safety feature but there are aircraft like the V-22 which can't autorotate which are perceived to be more dangerous when compared against their contemporaries despite the [multi]decade development gap.
01:00 The "Abort Switch" on the Apollo missions had the risk of single-point-of-failure, it was, after all, only one engine to bring the astronauts back up. So in case of a single engine failure, they would have been stranded on the moon or would even have crash-landed. Not so much of a backup.
Yes but the abort mechanism was the same as the method to get off the moon once landed anyway. They went to the moon with this in mind, so you put all your energy into sacrificing reusability for reliability into one switch. This is why they used a hypergolic propellent, one that always ignites when both parts come together which is simpler (less points of failure) unlike the raptors which need turbopumps to feed in fuel. Of course you cant reuse the hypergolic engines but you can the raptors. At least with rockets you inherently have to sacrifice something for reusability. If you make a rocket reusable, its to decrease time in-between launches and cost of materials. You dont focus on one launch so you have to have more "faith" in your system a lot more then a one time launch like the Apollo missions. Each launch for Apollo was specifically tailor made to ensure no failures. This obviously is more costly but we take the cost for the sake of valuing the lives at stake. For the sake of reusability you have to accept some failure. So at this point its a moral issue of the lives at stake.
when it comes to Flat Earth, I HIGHLY recommend the Folding Idea's Video "in search of a flat earth". Way better discussion of the topic then Scott's light touch on it here.
Where can i go to have serious discussions about Grimm's Fairytails? If putting time and effort in some, i might as well use the culturally precious ones. And not ones that were disgarded 2300 years ago. Until some idiot came along in the 20th century and socialmedia with some more idiots who (mostly) think that it's funny.
I watched something on it once out of curiousity I wanted to see what kind of crap they believe. Next thing I know youtube SPAMMED flat earth on me. I'm like EWWWWWWW GO AWAY!!!!! Took a while to clear out those videos.
@@awilliams1701 which is talked about in the first section of the video i recommended. It starts by proving the earth is a globe as well In search of a flat earth is NOT a video trying to claim the earth is flat, it's about why proving them wrong doesn't matter that much and where the beliefs come from and have gone to.
What I've been wondering about Starship as it pertains to human spaceflight is how the flip maneuver is going to affect any passengers on board. Like it's a very harsh maneuver, and while I'm sure the g-forces aren't too high, the rotational acceleration is severe.
Re: Flat Earth Theory. I think that a lot of people feel that if a large institution is lying to them then it makes them feel a little important. I think that a lot of the appeal of conspiracy theories is that it suggests some agency on those that have been conspired against.
A large institution is lying to them *and they figured it out!* They get to feel important AND smart, unlike all the sheeple how don't realise what's going on. Plus, if a large institution or a government is lying and covering things up, at least somebody is in control. Sure, they might be evil and whatnot, but at least there is *some* hand on the tiller, someone is directing what happens.
@@ultima8250 Pretty much. I don't think it's a complete thesis, but, watching the news these days it looks to me like like what a lot of people want is a feeling of AGENCY. Flat-earthers or Qanon folks get it in spades. A feeling like you're not just another cog in the machine. Gun nuts too.
No matter the initial reason,conspiracy theorists still need two key ingredients: Willful ignorance (to beleave the conspiracy theories in the first place) and extreme arrogance (to fortify the Willful ignorance when faced with reality)
I don't recall if there is space insurance/fees in Planetes like Scott mentioned here, but I wouldn't be surprised if there was, it fits the show very well.
@@Xatzimi The opening of the first episode (and the beginning of the manga IIRC) is a tiny bolt plowing through the window of a sub-orbital spaceplane killing a bunch of passengers. Unfortunately, I think it would take a similar incident in real life to make people care about space junk in the long term.
The other big limit to rocket engine throttling is injector pressure drop. As the mass-flow rate through the injectors drops so does the pressure drop and this allows more instability from the combustion chamber into the supply lines. Past a certain point this leads to combustion instability and "bad-things" in the engine.
Planetes is excellent, maybe with enough comments we can get Scott to do an episode on it. He did do the narration for the "Did You Know? Anime" episode on Planetes, but that doesn't necessarily mean he watched it himself. If not, I hope that can change
Making an entity pay to bring down their junk after it is finished with could lead to 'temporary organizations' launching things so there s no one to ask for money as when the date comes it'll already have shut shop. The temporary being a variable that depends on the circumstance. It's a nice idea but there are loopholes.
That’s a good reason to require that LEO/MEO satellites be sent up with the means to deorbit at “decommissioning”. You could also require a deposit at the time of launch for “decommissioning or recycling expenses”
Real reason SpaceX wanted the Air Force contract is obvious, get the Air Force to cover the cost of developing a fairing that can launch more starlink satellites in one shot whilst waiting for starship to be finished .. of course the contract itself is helpful ..
Yeah. Falcons with current fairing don't use their maximum power and Falcon Heavy is VERY rarely used because of this (on paper it has best LEO cost/ton)
No, number of Starlinks on F9 is mass limited, not volume limited (although it's near). And FH don't really make sense for Starlink launches. If you try to recover all cores, F9 has actually same or bit better $/kg than score than FH.
That was the problem with Radial Flow Gas Turbine aircraft, because it provided lift, thrust and control, if your engine cut out, you just fell out of the sky.
Regarding question #2 the thrust to mass ratio remains constant no matter what planet you land on. It's the weight that changes, so it would take less thrust to hover, but the same thrust to decelerate.
The last-minute power-landing makes the starship design a real-time computing challange. i.e. if something goes wrong then there is not much time to correct (if possible at all).
Someone had an idea of putting Crew Dragon as a nosecone for Starship (where header LOX tank right now) to have a launch/landing escape capability. It's already certified for human flight so why not?
Also, the raptor takes forever to spool up so you have to make sure it will reliably produce the thrust needed (a little bit in the future) so you know when to fire up the next one if needed. Personally, I think they need a smaller, more reactive engine for landing but, hey, I'm certain they know these things better than I do. Still love watching the progress 😍.
@@keonix506 I've thought this for a while. Even better, just carry the dragon (or multiple) into orbit or at a space station, then use it only for landing crew. Space/Moon/Mars can all be done with Starship on it's own. Keep Earth landings (the hardest) for uncrewed Starships.
@@-danR if you think nobody believes it then you don't know humans. You literally can't claim that nobody believes it when the people act like they do and give money to people who preach the flat earth.
@@joehorn1762 Especially when it leads to ridicule and general continued failure in life. No one carries on a troll or a joke to that extreme for decades.
Regarding Starship landing safety, I'm also very skeptical, but there's one thing: rocket engines are reliable because they can be prepared before launch, they can be tested and if anything goes wrong, the launch can be delayed for maintenance. With current starship, engines are used, then switched off, and then started again, shortly after they were under heavy load. In practical scenarios, things may be done differently. For flight between continents, different engines could be used for landing than for launch, and they could be fully prepared for use before launch. And for travel from orbit, engines could be tested and maintained in orbit before landing. Plus there may be some spare engines ready for use. Sure enough there's ton of technical difficulties that need to be solved about it but in general this approach could make landing about as safe as launch.
I know that wings are considered dead weight by most rocket engineers, but they don't have to be switched on at the last second in order to avoid FIERY DEATH for the crew within.
Perhaps the second generation of crewed mars transports will have shuttle-like planetary transports with parachutes/airbags that never leaves the martian system.
Astronauts are masters of managing risk... but to have complete confidence in Starship' bellyflop manoeuvre?... that would take a special kind of crazy that astronauts aren't know for. Starship launch to orbit and beyond seems extremely practical... crewed landing though ? How about traditional manned parachute capsule from Starship's payload bay with a "hopeful" automated landing by the Starship.
They'll probably either launch the astronauts on another vehicle to dock with starship, or launch on starship. I doubt anyone will actually land on starship though.
Wait, did i here future space debris removal company? Does have a suspiciously similar taste to a great space anime called "Planetes", if you haven't watched it, watch it. It's a must for every space enthusiast that dreams about the near future. ;D
When I was a teenager, I believed in some of the conspiracy theories. IMHO the main reason why people believe in them (or at least for young people like I was then) is that it is a "secret knowledge". If you believe in a conspiracy theory, you feel like you peeked behind the curtain. You know the truth that others don't, so you feel special. It feels more like living in the movie that you liked and make your life less boring. I think that people using conspiracy theories to blame others for their own failures is only valid for the most hardcore believers.
Scott, your video about the realistic spacecraft using the pendulum and cables to create artificial gravity got me thinking about this: What about a spacecraft that uses cables, reaction wheels, and winches to deorbit space junk like a yo-yo? All delta V lost by the target craft, is gained by the operational craft, so it starts low, and keeps throwing things down into atmo, while raising itself to it's next useful orbit. Obviously there isn't enough delta V to change from polar to equatorial or anything crazy like that, but are there enough satellites in similar orbits that a mechanism like this could work?
So here's an interesting idea to work on. What if instead of throttling an engine with the combustion products, we do it with the physical dimensions of the engine itself? Could we, for instance, create a variable-geometry rocket nozzle and throat that would change the amount of thrust for a given amount of propellant burned? This would take a lot of time and such, I know, and it would be very complex, but in some applications it could be very useful. You could glue one of these to the bottom of a solid rocket motor to have a variable-thrust SRB. The nozzle could also adapt itself to atmosphere pressure, so you don't need separate ground and space engines; this would allow you to take less engines, less weight, less complexity in the plumbing and procedure. A simple PID controller could automatically modulate the engine geometry to get the highest possible ISP or thrust for a given situation.
I think that would be possible with aero spikes. Similar to the cones on the hybrid engines of the "Black Bird" where the cone is pushed forward or backwards to decrease or increase the flow. I'm no scientist but that _could_ work... but it takes brain power i don't possess. Good luck with the heat... just saying 🗿
This is one person apart from Dustin from smarter everyday and everyday astronaunt, i would like to win the dear moon competiotion. They are most deserving of it!
I'm a follower of Jesus Christ myself. Therefore I'm a Christian. So when Christianity gets into this Flat Earth nonsense, it stings because that only hurts us who are genuine believers of Christ. When I see our giant marble and other planets, I just think how awesome God's creation is. Science and God are 100% compatible, so I take comfort in worshiping my Lord and enjoying the wonders of his creation through the lens of science.
What makes you skeptical about the safety of the starship landing? Where is your skeptic based upon? Have you seen Wright brothers' plane, weren't you skeptical about that?
10:26 to 10:44: "And, first of all I think that argument is bogus because I think if you're, like, a real super badass God, you're going to create a universe that's 17 billion--whatever--56 billion light years across, with hundreds of billions of galaxies and stars and stuff--you're not going to create a tiny disk like this with a dome over it." --Scott Manley That is the quote of the day.
That movie you mention, Stowaway...it wouldn't happen to be inspired by a certain short story written by Tom Godwin, would it? Because if so, that has rather specific implications for its ending. (Meaning, if you look up that short story, you may spoil the movie for yourself, so be warned.)
Hi Mr Manley. From my experience, science and belief in God are in no way mutually exclusive! (9.54 sec) P.S I've been a believer for decades, met 1000's of Christians, spent 7 years at Seminary and and, and, and have never heard one person ever make any such claim - like never ever!
Forgive the directness, but are you American? This seems to be a problem unique to certain areas of the US for reasons I don't understand well enough. But those same areas, while nominally "Christian," often are the most prone to misinterpretation. For a better perspective on their non-exclusivity, the youtube channel Sixty Symbols (hosted by Brady Haran) interviewed the head astronomer at Vatican City
@@Xatzimi Hi Lucy. I appreciated your comment. You are very astute in such matters. But while I'm not from the U.S.A l may fit the idea of a fundamental Christian.
@@Xatzimi Fact is, there are many believers trained in astronomy, zoology, etc, and are comfortable in their fundamental skin. Look up "Answers in Genesis", "Young Earth Creation" and "The Science Channel".
The Flat Earth Society reports that all the social distancing is pushing some of its members over the edge.
🤣
Nice
Won't be the first edge the poor goons have been pushed over.
Not to worry, there's plenty of idiots down there to break their fall.
If only.
It's really sad that Scott has to take time to answer this. And no, it's not sad that the world is such that FE people exist and spout their nonsense. Because I never hear from them, but always hear about them from people who can't stop talking about them, and have given them more energy and popularity than they ever could achieve on their own. All because people are obsessed with a notion that society needs information policing in order to prevent some sort of decay in intelligence and/or prolonged social injustice. You just need to stop talking about some things and they will virtually disappear.
Best quote ever, "If you're a super bad-ass God, you're going to create a universe with 56 billion light-years across, and hundreds of billions of galaxies with and stars in them... you're not going to create a tiny little disk with a dome over it." -- Scott Manley
I agree...flat-earthers drool and God rules!!!!
The sad thing is, some *human* minds can't wrap themselves around anything bigger and/or not human-centered...
But its not a super bad-ass God, seems to be an incompetent student who failed a chemistry experiment.
@@stardolphin2 Yeah so? And who are you, oh human, to condemn them? You're just a slightly smarter ant in the ant hill.
@@chrismusix5669 That might be okay, if they didn't constantly go out of their way to spread easily *falsafiable* ignorance (as opposed to unfalsafiable faiths...by definition, that's outside of science).
It wasn't a word I used before, but yeah, I do condemn determined, contagious ignorance. And who exactly must I be to do so? I'm no teacher, but their profession *exists* for the very purpose of reducing ignorance. Sincere Flatties (as opposed to amateur or professional trolls...check the comments in many NASA.com or Space.com Facebook postings) generally don't have the excuse of being children that are still relatively new to the world, and know little beyond their immediate, personal experience.
Flatties insist that that's *all* there can be. Yes, I plead guilty to having zero patience with that, in the face of endless evidence to the contrary.
Scott: hard for me to see how they will make starship landing safe enough for human flight.
Also Scott: Dear Moon here I come!
Gotta hedge those bets.
The question was a bit blurry anyway. Before the landing you have to get there. Between there (moon) and there (Mars) is enormous difference. Could mean days or months in space. Think about big machines that go for months without problems. And not a parking, landing or docking away from having a mechanic checking it out. You better be sure about that.
The actual landing is only a tiny part of that. And as he says, with a single stage lander you put all on one card. Potentially 100,000,000 km from home.
They will have to have some sort of launch escape system similar to the crew dragon. I'd imagine they could integrate it into the nose of Starship and have any crew/passengers in that section of the ship during any maneuvers. That way any time they're launching or landing the crew and passengers have some means of survival if Starship fails a landing or has issues during launch.
At some point SpaceX will make it very reliable and then decide to put people on it. People will choose to fly on it. People jump off of cliffs with wingsuits. Sometimes they die.
Landing on the moon is different compared to landing on Mars. You don't need to have a flip manouver, therefore you can start the engines earlier and "test" them. On Mars, you brake with the atmosphere and light the engines for the flip manouver and landing. If there is an issue at this time, it's probably over
The best solution I've seen for space junk is the "bottle deposit" idea: when you launch something into orbit you have to pay a fee, as a deposit against its eventual deorbit. If your satellite fails to deorbit, the deposit is used as a bounty, paid to whoever brings it down. Garbage collection companies can now profitably de-orbit junk for the bounty.
That's actually really neat.
Now you just need the world to agree.
There is already policy in place to require satellites to deorbit or to move to the "graveyard orbit" once they reach the end of their usable life. But I like the concept, it's a good idea.
@john smith I've been meaning to watch that series.
For the safety issue: different people accept different levels of risk. Hardly any of us would do something that has a 10% chance of killing us, yet lots of people are still climbing Mount Everest every year at those odds.
that's because the people climbing everest think they are good enough it won't happen to them
they are arrogant and most of them think their skill is above average :p
Podkova
No, because it isn't just yourself that you're putting at risk.
I wonder what the risk of driving is % wise on average.
Famously Ed White said: "IF we die we want the space program to get on. It's bigger than us." Which given (Apollo 1) history is a chilling and powerful statement.
It's hard to imagine a Space Tourist saying that. Or another one buying a ticket after a fatal fail.
We also heard "it will be as easy and casual as taking a shuttle on the gorund" before. There is no unsinkable ship and Elon's will be no difference. Promising casual riskless space flight WILL come back to bite you in the arse. People climbing Everest KNOW the risk. Or if they believe somebody that it is easy, they are stupid.
While risk is a faint concept from another universe for most SpaceX fans. And Bosses.
@@donsample1002 In the United States, who exactly am I putting at risk by going to the pub? The pub goers are all consenting to be there. Everyone at risk has already been vaccinated.
Thank you for answering my question about throttling and the lower ISP with lower throttle. Also, the little tidbit about the RS-25 being able to throttle down to 10% blew my mind!
Yes, but there is a big chunk in the middle of the throttle range that is not good to stay in long, you transit fast, because there you will have instability.
do you think it's viable to detach the SLS engine assembly and land it back on earth? kinda like how ULA plans to reuse their engines
@@1224chrisng do you mean like trying to land it it like the center section of a Falcon Heavy? At this point it would probably be a bad idea to add a level of complication to the program. You'd definitely have a lot of variables to balance, like, what exactly are the throttling windows, how much mass are you landing, how can you adapt a landing leg solution to the current architecture, and for what cost in mass, and then where does all that put you in terms of flight profiles.
@@weatheranddarkness no, I mean the ULA's plan for SMART Reuse, they have a detachable engine section
@@1224chrisng ok, that's what I thought at first but then I wrongly assumed you were asking about something much more reasonable. Attempting to retrofit a system like ULA's would most assuredly explode the cost of SLS. It would add maybe less weight than legs, but the complexity would give all the SLS contractors a field day(decade) to implement at absurdly inflated cost.
I just love it when he says “fly safe”
I'm waiting for a cat with the body of a bank safe and a tail of rainbows to come flying by..
WHY, THAT MEANS THE VIDEO IS OVER
I love the little opening music bit with the rocket
I'd prefer if he said "fly safely". 😊
Fly high, stay in may
Keep smoking life's a joking
Happy money for yourself, milk honey
Rockets moons suns, food dockets come!
I have a question: where can I get a t-shirt that says "Beam me up, Scott Manley!" ?
On a site that sells custom T-shirts? Or just post it into the internets a bit and wait for chinese bots to pick up on it and presto, some will be available in some shitty chinamart.
I’m glad you put the comma in.
That and the "Great Scott Manley" are the best shirts.
I think I have a good design idea but first I need some sleep
make one? silk screen is super easy to do, especially these days with nice printers to make your mask with
Listening to Scott explain things is like listening to your favorite uncle explain something complex; very informative with not a hint of condescension. Which in this case, for me, is weird, because I'm probably twenty years older than he is.
All my uncles are either morons or dead morons.
@@Connection-Lost I only have one smart uncle but he's an asshole :(
It's not an age thing, it's an enjoyment and respect for the subject matter, and wanting to share it with others by coming together. You can see it in Scott's face and hear it in his voice, he thoroughly enjoys it himself and just wants others to feel that way too.
@@bobblum5973 It does show, doesn't it. Fly safe.
@@miinyoo You, too!
Re: "The Expanse" question: They weren't using the RCS thrusters. They had to use the keel-mounted railgun since it used a separate power supply from the rest of the ship (it's own bank of batteries normally charged by the fusion reactor). On top of that (and I don't recall if the show has this), the Roci was pretty badly damaged from the corporate's light shuttle/bomb getting turned into shrapnel, so several of the RCS thrusters were damaged beyond repair outside of drydock. Because of the shrapnel impacts, and damage to thrusters, they were in a very complex tri-axis spin, and had to time the railgun shots just perfectly to impart the correct direction of thrust on both ships. The rail gun couldn't have fired continuously because of the complex movement, and the fact that it probably would've melted.
Finally, they can't "move about... with impunity", they *do* have limited fuel in the form of reaction mass, AKA extremely pure distilled water which they use for potables, coolant, RCS "fuel" (they shoot out steam), and for the Epstein Drive.
Great explanation! Let me just nerd-out about Expanse a little here: In books they actually care about reaction mass a lot, ie 5th book, after high speed chase with Inaros, when signal from Chetzemoka appears, Holden stresses out about Rosi not having enough of mass to turn around and intercept Chetzemoka. That's why Razorback goes there instead, being on more favourable trajectory. And there are more examples like that. Autors have been deliberately vague about workings of Epstein Drive (ED) and show even more so, to not get into shouting matches with space nerds. But that doesn't mean they don't have theory. In books there are ships equiped with fusion reactor, but without ED (not shown in show), that care about reaction mass even more, being able only short runs. That leads me to ED not being just better (stronger, more efficient?) fusion reactor (that is pretty much treated as free energy source, as when they get hands on Rosi, they note she is stocked up by fuel pellets for decades of continuous run) but some other part of propulsion. My theory is ED being converter that allows huge variability of reaction mass insertion, ie you can inject just few molecules of water, concetrate full power of reactor on them, heat them to few millions of K and eject them, therefore reaching truly insane Isp of reaction mass and saving it. Trick is, it is not energy efficient in this mode, but reaction mass efficient, maybe only 1% of energy of reactor is used (energy being free resource, as explained above. Another question is, where the rest of energy go? "Magic!") and raising Isp thousand-fold. This is used in low G burns. Or you can go full throttle, flood ED with reaction mass, get near 100% energy transformation efficiency, much lower Isp out of reaction mass and high G burn. I am yet to find passage in the books incosistent with this, but until authors speak up, we will never know. :)
Guys, seconds ago I found an original newspaper from the 21st July 1969 headlining "The First Men Are On The Moon" under heaps of other stuff my late Dad had stored in the basement! He never told me about it. I was short of two years old back then.
That's a cool souvenir!
Put that find under glass. That's going to be very valuable in the distant future.
Awww, so cool!
I bought the LA Times on the day we landed on the moon; still have my copy. Even at 13 I knew it would be a momentous issue.
I invoked your name when I saw a post saying something like, 'Why blast your enemies into the sun when it takes significantly less Delta V to launch them clear of the solar system?' I said, "Scott Manley Approves this message"
That gas choke condition explainer was super helpful. Makes a lot of sense that it kicks in after you cross the speed of sound, but I'd never heard anyone explain it that clearly before.
The Expanse has FTL so I'd not expect much. I like the thumbnail letting us all know that the real proof the earth is not flat is that cats would have knocked everything off if it were.
The expanse does NOT have FTL except when using the "Ring".
ALL of the spacecraft maneuvering in the solar system is via normal propulsive means.
These videos are heartbreaking because we will never get full videos on many of these topics.
I sorta think this is opportunity to sift the best topics..if many people ask about a particular thing, then he might consider making full length videos ey
If Scott hasn't covered it then EverydayAstronaut probably has
@@AbuctingTacos I don't think that would be the case. Tim certainly goes into immense detail with his hour long commentaries on a topic, but Scott has got him beat in breadth and sheer number of topics. These days I see Tim mostly working with live streaming Starship development. I hope he does another deep dive video again. The last one he did was about Starship and that was 5 months ago.
@@masonqian6964 he will release videos about belly flop and video about Soviet engines soon (tm). But yes, he has really low upload frequency
@BullShark He built a studio to provide better coverage of everything happening in Boca Chica and insurance paid for his wrecked tesla. Whoever told you otherwise is lying
Another reason for all kinds of conspiracy theories is that it’s an easy way to find social acceptance. No matter who you are, if you just believe the same strange thing, you immediately get accepted as “one of us”. Being an accepted member of a group is a strong drive for humans, and some need to resort to conspiracy theories to fulfill that need.
Agree 100%
Hope you’re having an awesome Thursday Scott! Everybody have a great day and prepare for SN15 testing 🚀
WOOOHOOO
@@AndrewSteffenHB BAAAAAMMM 💪🚀
@@BakuganBrawler211 Whamm bam Rocketcam
Hope you're having a great day Mr. Manley!
Flip safe!!!
@@forgeskygaming3355 *sn9 yeet noises*
@@legalnut9950 LOL
It occurs to me about Starship: The sea bottom is littered with the wrecks of wooden ships. Now hundreds of years later losses at sea are all but unheard of. But we never would have gotten here waiting for the Queen Mary to be constructed. We don't need to be completely reckless, but if we're going to get anything done we probably need to be a little more risk-tolerant again.
The only problem with that argument is that there is/was no snowball effect at sea. Yet, if one unlucky satellite blows up just the right way and causes a chain reaction in near earth orbit we might lose alot or all satellites and also might not be able to go to space for a very, very long time. That would be quite catastrophic.
Re flat earth: people like to feel special, and like to feel that they know something others don't know. The trouble is, it takes a lot of time effort and intellectual humility to go and study something and EARN that special knowledge. So instead, they short cut the whole thing by "studying" TH-cam and finding conspiracy theories that take minimal effort to feel convinced and which they know few people will believe. The more others resist, the more they become "sheeple" and the more special the individual feels. It's a circular logic, sure, but that is part of it. Even the logic loop itself gives them an odd kind of security because it reinforces the in-group/out-group dichotomy. Social Media then, with its anonymity and short comment length is an ideal environment because of its lack of accountability and the lack of need to offer evidence or rational argument.
Sorry for the long and probably obscure post. For reference, I'm a sociologist and my field is normativity, that is, how people construct their world and apply 'norms' to maintain it.
Your response is why I still scroll down to the otherwise mostly inane, cynical, and incredibly inarticulate comments. Thanks, Sophie!
@@generalyellor8188 Thanks 😊👍
Have you ever considered doing videos that would tackle this subject in this way? There are so many youtube debunkers that use science, math, and evidence to debunk, but I haven't really seen any that talks about the psychology or sociology behind it. I would love to hear people talk about this topic (and other conspiracies) using this framework!
Thank you for saving me to write that myself.
I am not a sociologist or the like, but I encountered some hard conspiracy theorists... I always had the feeling that they just wanted to "know something"
@@PsychoMuffinSDM Actually, I have considered it, I even put all the equipment together and did a few trial runs, but with such an anti-intellectual, anti-social/behavioural science attitude being so prevalent these days, I don't know if it is worth the effort of putting up with the willfully ignorant. The other problem is that the kind of science I do frequently conflicts with political bs and deeply held prejudices that people cling to. Science is of course, based on evidence rather than belief, but it nevertheless, doesn't happen in a social vacuum. I wind up getting so frustrated by dealing with the endless stream of abuse that my partner makes me take regular social media breaks.
Thanks for your comment though. I really would love to do something like that and perhaps if I could develop a sense of community where there is a core of people who are genuinely interested in it, I'd revisit it.
For what it's worth, I agree with you. Perhaps if we could break this idea that the only true Science is physical science, we could make some progress... Not just on TH-cam but in society in general.
I've actually thought about posting some of the classes I used to teach about culture, identity, power, sexuality and world affairs. Would that be interesting to you?
I‘d love a video about tethers in space. It seems like there would be so many fascinating interactions there
And there's a reason why when the space shuttle did "pull up" on ISS, they never used a tether.
If you havent seen the trailer scott mentioned go watch it, He does a little breakdown on it and its pretty cool. Would not surprise me if spacex or nasa or someone starts testing it irl.
Flexible tethers would be kinda weird in 0g. The tension pulls spacecraft together, but nothing stops the craft from continuing to move to each other and colliding.
Maybe solid telescopic rods or long modular structures that'd be built on site would work.
@@emiel2712 I wonder if it would be possible to create a flexible tether that can transmute (think that's the right word) into a more solid one, perhaps with an electric current. I imagine it would be a good idea to make the process reversible or perhaps adjustable as well, a little bit of flexibility could prevent the tether from snapping under load.
I love this series.
These are the questions you get as a rocket nerd in everyday life.
Yes, a tether episode would be interesting.
A couple of points about the Starship.
The atmosphere on Mars is so thin that you would think that the vacuum Raptors would be used for landing but the current design is with three fixed Raptors outside the three movable air Raptors in the center of the rocket. This means using the less efficient air Raptors for landing is necessary.
Using only one Raptor for landing is a bit silly since it means a leaning Starship when landing. Two is better but the thrust is still off center. With an empty Starship this seems to be necessary but deep throttling for a three engine balanced vertical landing would be better. Hopefully the improved Raptors Elon has said were coming will allow for deeper throttling and balanced vertical landings.
Love that you post these here! Some of my favorite videos of yours. Really relaxed questions we all think about sometimes.
15:50 if I remember correctly in the book they were using the roci's rail gun which itself needed the ships main thrusters to normally counteract its recoil and firing it normally to their orbit to shift it and buy time not to keep them in orbit indefinitely
never seen how the show did that scene though
It was pretty much the same
I like the format of the Q&A. Thanks for a another great video. :)
I'm a Baptist, and attended fundamentalist Baptist churches while growing up. I never heard anyone claim that the Earth was flat, or a flat Earth was required to show the power of God.
@12:30 One big reason for vertical integration is that horizontal integration, especially for long payloads, requires a lot of structure to support the cantilever forces when the payload is horizontal and only supported from one end.
A structure that only needs to support its weight vertically can be made much lighter than one that has to cantilever from one end.
In this regard there could be some solutions to still integrate horizontally, such as having some temporary external structure supporting the payload that is then removed after the rocket is vertical. However that still imposes a lot more effort on the client. Generally the client (designer/builder of the payload) would rather not have to worry about designing their payload to withstand stresses that it needn't be subjected to.
Sort of. If you look at your copy of the Falcon Users Guide (August 2020) page 16, for loads over 4000lbs the lateral acceleration will be less than +/- 2g. So loads should already take horizontal loading (1g) into account. What, you don't have your Falcon Users Guide on you? I suppose you forgot your towel too... OK, here is one. I'll trade you for a Red Dwarf technical guide :-)
Thank you Scott
for everything
What the fuck how is your comment 2 weeks ago HAY
@@helicocktor TIME BANDIT!!!
@@Noone-jn3jp OP might be a Timelord
5:00
Scott Manley trying his best to not make rude signs with his fingers
6:14 he failed
I'm enjoying these little chats. Please keep them up as long as people keep asking.
My question: How much of the propellents used to put vehicles into orbit comes back eventually due to gravity, and how much is lost to space forever? Are we creating an erosion problem for some of the rarer stuff, i.e. helium used as a pressurant, and how imminent is it?
I really appreciate these viewer questions answered videos. You're under no obligations to continue them of course, but I'd be really jazzed if you did. Thank you Scott!
Anyone who has ever towed a stranded car knows that if you try towing in space it will just rip off your... space bumper or something 😊
If you have ever towed another car with a rope or cable, you will likely have experienced another problem with towing in space. Getting rammed by the thing you're towing due to recoil from elasticity of the tow line and the energy lost from imparting it to the towed object slowing you as it accelerates the towed item.
On roads, you also have to deal with the problems when the tow vehicle wants to slow or stop, if there is not control over braking in the towed vehicle.
I have a question that, When a rocket flying through air then does it becomes a charged body by friction? If yes then any problem can cause to the rocket and how they discharge it?
I don't know what they do on rockets but on planes they have static discharge wicks on the trailing edges of the wings/tail. I wonder if rockets do something similar?
For vehicles that return to ground instead of splashdown, there is a ground strap that contacts the ground first. You can see it on the legacy shuttle and SNC dream chaser next to the wheels. The soyuz has a conductive spike antenna released with the parachutes.
While the rocket is in its launch phase, the rocket exhaust is conductive so the rocket and exhaust are basically the largest lightning rod ever. Apollo 12 suffered two lightning strikes during its launch, so it can be a problem. Scott Manley has a video on Apollo 12 if search for "SCE to AUX" on his channel.
For the expanse episode, they were using their railgun as a rudimentary thruster, and they could only fire it fast enough to barely maintain their orbit. They also designed a clamping system to absorb the jerkiness of the thrust, and a software program to aim it as accurately as possible to ensure the vectors all balanced out.
Really nice point about the badass god and the giant universe, I'll keep that in mind for my next encounter with flat earthers
Haha, Scott, from having worked in the defence industry, I bet your theory about vertical integration is bang on :P
What if it is a Space-Earth missile inside? That would also make a sense. Or not?
@@luboinchina3013 Why shouldn't they be able to lay a space missile on to its side?
I'm outside at a patio table and a cup of coffee. I'm so into the video that my cat jumps up, gets tired of being ignored and pushes my cup off of the edge.
On the expanse scene: They were trying to quickly burn prograde to raise their orbit. Later they continued this by shooting the railgun in retrograde direction, further increasing their speed by the recoil.
The ships were so low that they were encountering a lot of air drag. Since they were relying on their fusion drive this would never be a problem. But without those the ships would be slowed down and reenter in a couple of orbits.
whoa! Kerosene + HTP requires no cryogenics. Surely that saves weight, must be more reliable, and helps with logistics (ie, you don't need to fuel immediately before launch). You don't have to worry about weird bubbles in the tanks. Surely all these things are worth a little bit of specific impulse.
Assuming your HTP doesn't blow up. Allegedly like the Kursk or HMS Sidon (I have not verified those stories, they are on Wikipedia). By the time you've diluted it to stability, you've lost some performance.
as a Christian, and a engineer, i view science as a means of showing God's might and intelligence. to me it shows that the more we find (law of physics and such) lends itself to there being a creator that sets and holds these properties in place. as if there was no creator force, what makes these laws happen. as for the person you mentioned, their teacher is horrible misguided at best. there are many wolves in sheep's clothing in our ranks (Christians) that unfortunately don't fully read or comprehend the bible.
@@mcs699 you can't disprove the existence of God, so its not really anti-science. There are plenty of scientists that are Christians. Think about it, if matter cant be created or destroyed, then how did the big bang happen? Something supernatural had to have created the natural universe. God said "let their be light" when creating the universe. The big bang was an exponential expansion of light and matter. God essentially sparked the big bang.
@@mcs699 so then why is the evolution theory accepted in science as truth, yet it isn't proven?
@@mcs699 am I wrong? If the evolution theory is accepted as scientific truth then why is it not "anti-science" since it isn't proven?
Keep in mind that the bible was written (and collected from older bits) by humans! Tribal humans at that. Everybody can do with the philosophical, moral part of it what they want. Even that need interpretation, as it is often contardicting itself. Which is how Theologists earn their money.
But taking it as a literal source for science (whit the carefully sceptical exception of history) was and is stupid. Doing it literally but from a translated version is then completely idiotic. The whole Ararat thing is a good example*.
It's probably fair to assume, what these people wanted to convey, wasn't wether the earth is flat or what orbits what. They didn't know and very likeley didn't care about that.
* the original version apparently said "among the mountains of ararat". Translations changed it to "Mount Ararat". The one which was swarmed by Ark searchers wasn't even called Mount ararat at biblical times.
@@5Andysalive what parts of the Bible say things that have been disproven by science? If something hasn't been proven nor disproven, then why can't you think thats how something works? Scientists don't know what goes on inside a black hole, so what ever theories they come up with that aren't proven, can't be assumed to be correct, so if something from the Bible says something that hasn't been disproven by science, why not believe it? After all, there's nothing saying that what they said is wrong?
As for the flat earth comments, I'd recommend Carl Sagan's pale blue dot - he talks a lot about geocentrism and imagined self-importance. Incredible writing that I'm sure you've actually already read...
I grin to the fact that this video has 41 dislikes and over 4k likes. Clearly the Flat Earthers avoid someone as knowledgeable as Scott Manley.
Having just read “Ignition” (thanks for the recommendation) the author asserts that HTP wasn’t used much after the UK space programme ended because when it breaks down it is a run-away reaction (read BANG!) - and the USA and USSR had worked out how to work with RFNA based oxidisers when they needed dense liquid propellants..
"Ignition" by John Clark (now available as a paperback reprint) reads like a Steven King novel for chemists. Noooo, don't even think about ClF3! My mind is exploding vicariously.
Sutton: Rocket Propulsion Elements (original copyright 1949,) agrees: "It has not been used for a long time, partly because of its long-term storage stability." (quote from the Seventh Edition, 2001). Although Soyuz uses peroxide, it seems to be the limiting factor in Soyuz stay-time at ISS. Nothing makes me nervous like peroxide. The highest concentration I've ever handled was 35%.
Yes please do a electromagnetic tethers video! There's a ton of different tether topics (including things like skyhooks/elevators/etc).
I second this!
@@hanspecans Thirded! One tether application also ties with the space debris removal because a space tether can be a propellantless method for propulsion. Joseph Carroll's EDDE is one of my favourite concepts - the ElectroDynamic Debris Eliminator. 100 kg, 10 km long, with nets for capture at its ends and a small fleet of them would do the rounds up and down to clear all the old rocket bodies and derelict satellites in under a decade.
For anyone interested, I'm pretty sure the documentary he's talking about at around 11:00 is "In Search of a Flat Earth," by the youtube channel Folding Ideas.
I'm more interested why lots of people assume Flat Earthers believe in God and are religious. I'm a Flat Earther but I don't subscribe to any god or religion. I think that's all BS imo. My personal view is man fabricates his understanding of the natural world and God, the Universe, the planets, Jesus and much much more is all part of that fabrication. In other words man makes it all up using his imagination and in many cases convinces people using contrived demonstrations. So some forms of science is no different to believing in God!!! Welcome to man's fabricated world!!!
@@PeterPete You would be a minority then. Basically flat earthers in general (i.e. not you) take a couple bible accounts literally, and their misinterpretation of it is compounded by bad translation. Its a bit of a read, so skip it if that synopsis is enough:
In the creation account, some translators take "circle of the earth" from a word that could easily be sphere, and the vast majority of passages in the bible are written from a humans perspective standing on the earth. Thats why some get confused by things like a bird flies in heaven ( the sky) and a spirit realm.
Another passage says the devil showed jesus "all the kingdoms of the earth," and say the earth cant be a sphere because he wouldnt be able to see through the earth. However, they forget the other half of the scripture, and "all their glory " and, "in an instant of time". They also fail to understand that even if the earth was flat, there is no place from which you could see all of it at once. It has to be figurative and not literal, meaning he showed their power, riches, and influence rather then "the earth is flat, here is every kingdom from this huge mountain."
The creation account is also taken to mean literal 24 hour days.... despite the fact that the sun is created later in those days so earth "days" didnt even exist yet. Its also a translation issue... a day can mean many different lenghts of time. For example, when was your great grandfathers day? Probably around the 1900's.... but its not a literal day. Its more of an era.
There are others too, but I really don't want to write more, and don't want to try to think about them. But essentially, religion is probably the biggest factor in FE.
@@blackdeath4u The bible is a book made by man using his imagination. It is a book filled with metaphors to account for this thing we call 'life'. The bible mentions the firmament separates the waters above from the waters below. Imo nobody can ever come to know that even a firmament exists so this metaphor could relate to a woman's womb during childbirth, afterall the universe is within each and everyone of us - without us there is nothing.
Lot's wife turned to a pillar of salt after looking back at the destruction of Sodom is another example. In my understanding this is just a metaphor to compare turning to a pillar of salt to losing one's peace of mind. The image of something really bad can plague one's mind for the rest of their lives. Reminds me of Indiana Jones when he's tied to a pole and the Nazi's open up the Ark and he shouts to the woman to close her eyes, not to look at the spirits, flames, and bolts of energy that kill all who are around them.
So there's similar metaphors even in films and probably lots of other outlets too.
Lawrence Krauss talks of everything comes from nothing and I can agree with that, afterall, what came before me when I was born was nothing and what will be after I die is nothing and yet I, as an individual am the universe. Quantum entanglement talks of how two people can become entangled during a lifetime, yet I could call that true love. So there are similarities of meaning in religion, film, TV and even in parts of science. It seems, everyone talks about 'life' but they use their own language to reach out to their followers to help them understand it, inadvertently confusing them along the way.
It still does not get away from the fact that imo nobody can ever come to know the true nature of reality. Mainstream science stating oxygen is a constituent of the air is in my opinion man's best guess to explain what air is, but there is no oxygen as a constituent of the air because nobody can prove that. Lavoisier just convinced people using his imagination and a few demonmstrations!!
If you think I'm wrong you're more than welcome to prove to me there's 21% oxygen in the air!!!
Btw, the Earth is a level plane, the globe is merely a construct of man's imagination because men and women dislike the beastiality of life. I can sense another metaphor coming on - Satan, the Devil, the beast only refers to the animalistic nature of human beings. Haha!!! I don't want or need a dream existence!!
@@PeterPete lol
@@jaymanier7286 i can't hear you jay!!
"If you haven't watched [The Expanse Season 4] by now, it's a year and a half old..."
Me who only just got around to watching it last month: that's fair
The new shit that came to light about Cas Anvar made it a bit difficult to get back into it after the break I'd taken from the show.
@@weatheranddarkness Yeah, fair, though I try to keep art and the artist separate, it's not always that easy.
Still, it's worthwhile, especially in this case as it's such a good show
@@mduckernz doing so can be complicated though. Here complicated by fewer degrees of separation than I or my partner would liek.
Its feels good to have Scott do Q and A. He is just so thorough and complete in his explanations. So many questions i would love to ask! Also, props for the Maturity in addressing the kinda Religious subject of Flat Earth. Thanks Scott! Looking forward to more Q and A episodes :D
Even if starship is only ever safe enough to carry cargo that is still MASSIVE. the biggest hindrance to opening up space is getting mining equipment, building supplies, food, water, oxygen, etc, etc. To the destination. Even if starship is only used to build big human rated ships and stations in orbit, its still an absolute game changer
I've just finished reading the fourth book of the Expanse and yes, there are some problems with orbital mechanics, like them doing simple burns towards and away from ships to dock or meet instead doing the complex "messing around" that you have to do in KSP for example.
The docking stuff is mostly because in the expanse, they can afford to do that. They have torchships that can burn for months at 1g. The fastest way to get somewhere in a torchship is indeed to point (almost) straight at it, burn till halfway, then flip and burn to decelerate. You cant do that in ksp because we only have fairly wimpy chemical and atomic engines.
@@TheToric I meant the situation when their reactors shut down and they were flying around with their EVA suits. In the TV series it was a bit different and they were flying mostly with their ships, which probably had more delta-V, but in the book they were using nitrogen thrusters in their EVA packs which don't have a large specific impulse.
@@TheToric You also have limited fuel and so to do things as effectively as possible you have to tiptoe from orbit to orbit.
Anyway, once your close enough in KSP (km or so) you get away with pointing and flying.
Hi, Scott, thank you for this video.
Could you please explain: Why non-reusable rockets are always painted? They would have no time to rust, and paint weights a lot, also, paint on the top stage produces space trash.
Very valid question. I don´t have a good answer to it, too.
That's a *very* good question.
I think the early DH Comet jet airliners were polished aluminium to save weight as the first generation engines weren't over blessed with power ....
Reasons I can think of:
- Rockets are some sort of status symbols --> always a good opportunity to place a flag on --> flags tend to like a not-shabby surrounding ;-)
- Paint somewhat covers the structure --> less easy reverse engineering by just watching
- the parts exist long before the launch and in most cases have to be transported --> Paint ensures quality during production
- Launch sites tend to be next to shores --> salty air is agressive
- Launches tend to be postponed --> rockets have to endure a certain time without any risk of stuctural weakening
- Paint might be just not as heavy? I imagine they do not use roll-on wall paint from the store next corner
Also:
- there are rockets which are mainly not painted (Delta IV, Space-shuttle main tank, some old stainless steel rocket (Atlas ?) )
@@LoneStarr1979 I think stainless is a bit of a bitch to get the paint to adhere.
I'm sort of thinking as an anti corrosion protection as aluminium can and will - but in a nice, air conditioned assembly hall followed by a quick trip to the pad and then up I to space ... i wouldn't think that would be a problem...
But then, I ain't no rocket scientist.
@@LoneStarr1979 I am Russian, so i better know about russian rockets. We have no launch pads near shores, you can download Soyuz blueprint with all visible parts, parts doesn't exist too long before launch + everything is in hangar before crawling, transporting is fast, it tooks hours, not days. Also, our rockets are not white-blue-red, they are 90% white/ But, any vay, we also paint our rockets
Slight correction. Engines reduce efficiency during throttling because they're being put into a state where the turbomachinery, etc isn't operating at its design point. Turbine airfoils, pump vanes, injector mixing, etc. For nozzle design, it's really just about flow temperature (total temperature). Reducing the chamber pressure doesn't really reduce the exhaust velocity, especially in a vacuum, because once the flow is sonic in the throat, everything that happens after that is really just a function of engine geometry and gas temperature. And the absolute velocity is dependent on the local speed of sound at the throat, which is a function of just gas temp. You'll notice in a vacuum the equation for rocket engine exhaust velocity, the pe/p term goes to zero in a vacuum and therefore you'll note the only variables that matter are T, and the exhaust molecular weight. Also, Bernoulli's only applies to incompressible flow.
So, why then do pressure fed engines have lower specific impulse at lower throttles?
@@scottmanley Lots of reasons. As mentioned, injectors are designed to mix most efficiently at a certain jet speed (injector dP). Also depending on engine design, if you utilize film cooling/ face cooling the ratio of that to the core flow will be higher at lower power and since film cooling is combusted less efficiently, you lose performance there as well. If you expected Isp to scale with Pc, you'd expect a linear relationship with Isp and thrust. But in that case you'd expect for example the DPS on apollo to get like 30s of specific impulse at min power, which isn't actually the case. Injector c* is really quite sensitive to mixing
The question about space junk got me thinking. I gather a lot of satellites are quite small. I wonder how many could be captured in the hold of one of the space shuttles if they were on cleanup duty.
Deorbiting will always be a money pit, until companies realize that "junk" in orbit is basically free material, free of launch costs. Be decommissioned modules, satellites, whatever it may be. Notice how I said companies. This will always be a private sector venture, since public space contractors see nothing wrong with saving x by burning up 10x.
It's an amazing In Situ Resource, and needs looking into, or explaining away.
It takes more delta-V to significantly change the inclination of a low Earth orbit in space than to land on Earth and launch again.
When two objects in different orbits collide, it results in a lot of space junk being sprayed into space.
Anything designed to gather space junk will have to closely match the orbit of each piece of to catch it. Sane governments probably won't allow a company to launch something like a giant sponge to intercept junk larger than dust grains.
SpaceX has demonstrated that it is possible to launch thousands of satellites as part of one big project. It will eventually be possible to make something that can meet up with junk in a small set of orbits that are very close together in terms of delta V.
There is actually a space tug that is boosting a geosynchronous satellite that had a launch issue that left it low on fuel. This space tug can also move dead geosynchronous satellites into a graveyard orbit. The one tug might be able to move 2 or 3 satellites before it moves itself to a graveyard orbit.
Hey Scott, if you do look into tethers more, I highly recommend looking at the Miniature Tether Electrodynamics Experiment (MiTEE)! It's a project from University of Michigan that launched in January on LauncherOne that I worked on in grad school. It's looking into using tethers for propulsion in LEO.
Scott, as always, you are a gem to humanity. In regard to helicopter safety, not all helicopters can autorotate. Also... Jesus nut... Anyway, the ability to autorotate is certainly a backup safety feature but there are aircraft like the V-22 which can't autorotate which are perceived to be more dangerous when compared against their contemporaries despite the [multi]decade development gap.
01:00 The "Abort Switch" on the Apollo missions had the risk of single-point-of-failure, it was, after all, only one engine to bring the astronauts back up. So in case of a single engine failure, they would have been stranded on the moon or would even have crash-landed. Not so much of a backup.
Yes but the abort mechanism was the same as the method to get off the moon once landed anyway. They went to the moon with this in mind, so you put all your energy into sacrificing reusability for reliability into one switch. This is why they used a hypergolic propellent, one that always ignites when both parts come together which is simpler (less points of failure) unlike the raptors which need turbopumps to feed in fuel. Of course you cant reuse the hypergolic engines but you can the raptors. At least with rockets you inherently have to sacrifice something for reusability. If you make a rocket reusable, its to decrease time in-between launches and cost of materials. You dont focus on one launch so you have to have more "faith" in your system a lot more then a one time launch like the Apollo missions. Each launch for Apollo was specifically tailor made to ensure no failures. This obviously is more costly but we take the cost for the sake of valuing the lives at stake. For the sake of reusability you have to accept some failure. So at this point its a moral issue of the lives at stake.
when it comes to Flat Earth, I HIGHLY recommend the Folding Idea's Video "in search of a flat earth". Way better discussion of the topic then Scott's light touch on it here.
Where can i go to have serious discussions about Grimm's Fairytails? If putting time and effort in some, i might as well use the culturally precious ones. And not ones that were disgarded 2300 years ago. Until some idiot came along in the 20th century and socialmedia with some more idiots who (mostly) think that it's funny.
I watched something on it once out of curiousity I wanted to see what kind of crap they believe. Next thing I know youtube SPAMMED flat earth on me. I'm like EWWWWWWW GO AWAY!!!!! Took a while to clear out those videos.
@@awilliams1701 which is talked about in the first section of the video i recommended. It starts by proving the earth is a globe as well
In search of a flat earth is NOT a video trying to claim the earth is flat, it's about why proving them wrong doesn't matter that much and where the beliefs come from and have gone to.
I think a lot of flat earther’s have their reasons deeply rooted in religions. Partly to do with a failure of education, especially in science.
What I've been wondering about Starship as it pertains to human spaceflight is how the flip maneuver is going to affect any passengers on board. Like it's a very harsh maneuver, and while I'm sure the g-forces aren't too high, the rotational acceleration is severe.
if i remember correctly it's between 2-3 G's max. In theory it should feel something like sitting in a jet
Bernouli's equation work only with incomprehensible fluid flows
Re: Flat Earth Theory. I think that a lot of people feel that if a large institution is lying to them then it makes them feel a little important. I think that a lot of the appeal of conspiracy theories is that it suggests some agency on those that have been conspired against.
A large institution is lying to them *and they figured it out!* They get to feel important AND smart, unlike all the sheeple how don't realise what's going on.
Plus, if a large institution or a government is lying and covering things up, at least somebody is in control. Sure, they might be evil and whatnot, but at least there is *some* hand on the tiller, someone is directing what happens.
@@catfish552 Yes, there's a rush one gets from finding out the forbidden knowledge. I get the same rush from the sceptical movement.
This. Its just because some people want to feel important
@@ultima8250 Pretty much. I don't think it's a complete thesis, but, watching the news these days it looks to me like like what a lot of people want is a feeling of AGENCY. Flat-earthers or Qanon folks get it in spades. A feeling like you're not just another cog in the machine. Gun nuts too.
No matter the initial reason,conspiracy theorists still need two key ingredients: Willful ignorance (to beleave the conspiracy theories in the first place) and extreme arrogance (to fortify the Willful ignorance when faced with reality)
Regarding the space junk industry, it is the background of "Planetes", a very good manga and anime on space
I don't recall if there is space insurance/fees in Planetes like Scott mentioned here, but I wouldn't be surprised if there was, it fits the show very well.
@@Xatzimi The opening of the first episode (and the beginning of the manga IIRC) is a tiny bolt plowing through the window of a sub-orbital spaceplane killing a bunch of passengers. Unfortunately, I think it would take a similar incident in real life to make people care about space junk in the long term.
The other big limit to rocket engine throttling is injector pressure drop. As the mass-flow rate through the injectors drops so does the pressure drop and this allows more instability from the combustion chamber into the supply lines. Past a certain point this leads to combustion instability and "bad-things" in the engine.
Great answers, Scott. I can only imagine in the "after times" spending an afternoon with you and discussing "space".
In the anime Planetes, they explore space debris collection concept. Highly recommend. Good story and accurate physics, if I remember correctly.
The anime that showed us a future where being a astronaut is a blue collar occupation.
Planetes is excellent, maybe with enough comments we can get Scott to do an episode on it. He did do the narration for the "Did You Know? Anime" episode on Planetes, but that doesn't necessarily mean he watched it himself. If not, I hope that can change
Ahh I remember George Peppard doing space salvage in Salvage One in the 80s...
Andy Griffith.
Making an entity pay to bring down their junk after it is finished with could lead to 'temporary organizations' launching things so there s no one to ask for money as when the date comes it'll already have shut shop. The temporary being a variable that depends on the circumstance. It's a nice idea but there are loopholes.
That’s a good reason to require that LEO/MEO satellites be sent up with the means to deorbit at “decommissioning”. You could also require a deposit at the time of launch for “decommissioning or recycling expenses”
Thank you for being respectful Scott. Thank you. :)
Real reason SpaceX wanted the Air Force contract is obvious, get the Air Force to cover the cost of developing a fairing that can launch more starlink satellites in one shot whilst waiting for starship to be finished .. of course the contract itself is helpful ..
Yeah it feels like Starlink is their major commercial product that they're aiming for.
Yeah. Falcons with current fairing don't use their maximum power and Falcon Heavy is VERY rarely used because of this (on paper it has best LEO cost/ton)
No, number of Starlinks on F9 is mass limited, not volume limited (although it's near). And FH don't really make sense for Starlink launches. If you try to recover all cores, F9 has actually same or bit better $/kg than score than FH.
3 rocket questions at the start, and you know this one will be good
That was the problem with Radial Flow Gas Turbine aircraft, because it provided lift, thrust and control, if your engine cut out, you just fell out of the sky.
Regarding question #2 the thrust to mass ratio remains constant no matter what planet you land on. It's the weight that changes, so it would take less thrust to hover, but the same thrust to decelerate.
The last-minute power-landing makes the starship design a real-time computing challange. i.e. if something goes wrong then there is not much time to correct (if possible at all).
Yeah you have to imagine that for human cargo they will start the burn earlier. A long way to go yet for that, but watching the progress is exciting.
They now land on 3 so little bit more margin
Someone had an idea of putting Crew Dragon as a nosecone for Starship (where header LOX tank right now) to have a launch/landing escape capability. It's already certified for human flight so why not?
Also, the raptor takes forever to spool up so you have to make sure it will reliably produce the thrust needed (a little bit in the future) so you know when to fire up the next one if needed. Personally, I think they need a smaller, more reactive engine for landing but, hey, I'm certain they know these things better than I do. Still love watching the progress 😍.
@@keonix506 I've thought this for a while. Even better, just carry the dragon (or multiple) into orbit or at a space station, then use it only for landing crew. Space/Moon/Mars can all be done with Starship on it's own. Keep Earth landings (the hardest) for uncrewed Starships.
Can we all just take a moment to appreciate that Scott just said that all flat earthers failed at life. Love it :)
He didn't say that. It is an argument as to why some may believe in the theory.
There are no FE's. They do it for the lulz, and people 'debate' their arguments for the web-traffic.
Don't feed the trolls.
@@anthonyscott1997
Nobody believes it, any more than they believe crop-circle-alien claptrap.
This isn't like moon-landing denial.
@@-danR if you think nobody believes it then you don't know humans. You literally can't claim that nobody believes it when the people act like they do and give money to people who preach the flat earth.
@@joehorn1762 Especially when it leads to ridicule and general continued failure in life. No one carries on a troll or a joke to that extreme for decades.
Regarding Starship landing safety, I'm also very skeptical, but there's one thing: rocket engines are reliable because they can be prepared before launch, they can be tested and if anything goes wrong, the launch can be delayed for maintenance.
With current starship, engines are used, then switched off, and then started again, shortly after they were under heavy load. In practical scenarios, things may be done differently. For flight between continents, different engines could be used for landing than for launch, and they could be fully prepared for use before launch. And for travel from orbit, engines could be tested and maintained in orbit before landing. Plus there may be some spare engines ready for use. Sure enough there's ton of technical difficulties that need to be solved about it but in general this approach could make landing about as safe as launch.
I have to agree that vertical integration is probably a classified relic that doesn't need to be there, but nobody has changed it.
I know that wings are considered dead weight by most rocket engineers, but they don't have to be switched on at the last second in order to avoid FIERY DEATH for the crew within.
Perhaps the second generation of crewed mars transports will have shuttle-like planetary transports with parachutes/airbags that never leaves the martian system.
Hope your hayfever gets better Scott!
The Gemini program had at least one test where two spacecraft were connected with tethers.
Astronauts are masters of managing risk... but to have complete confidence in Starship' bellyflop manoeuvre?... that would take a special kind of crazy that astronauts aren't know for.
Starship launch to orbit and beyond seems extremely practical... crewed landing though ? How about traditional manned parachute capsule from Starship's payload bay with a "hopeful" automated landing by the Starship.
Considering NASA likes everything to have backups for the backups, I just cant see them putting people on Starship.
Maybe they don't have to, Elon can do it himself. His budget is bigger than Nasa. Space x can put whoever they want on it.
They'll probably either launch the astronauts on another vehicle to dock with starship, or launch on starship. I doubt anyone will actually land on starship though.
Landing people on starship is 10 years away, goto have reliable engines.
Unrelated viewer question,
Favorite food to eat while watching rocket launches?
Secret extra-long air force payload? It's Project Thor, man! The fairings will be full of tungsten rods!
While I appreciate your sign-off of "fly safe"... I'm gonna have to side with X-Plane 11's tagline: _Fly it like you stole it_
Wait, did i here future space debris removal company?
Does have a suspiciously similar taste to a great space anime called "Planetes", if you haven't watched it, watch it.
It's a must for every space enthusiast that dreams about the near future. ;D
Planetes is great!
When I was a teenager, I believed in some of the conspiracy theories. IMHO the main reason why people believe in them (or at least for young people like I was then) is that it is a "secret knowledge". If you believe in a conspiracy theory, you feel like you peeked behind the curtain. You know the truth that others don't, so you feel special. It feels more like living in the movie that you liked and make your life less boring. I think that people using conspiracy theories to blame others for their own failures is only valid for the most hardcore believers.
It's always the question, why these mysterious powerful people, fooling the whole world, could or would not silence these curtain lookers.
@@5Andysalive "Because it would prove them right" :D
But also often all critique is dismissed as smear campaign of those lizardmen- robots.
Scott, your video about the realistic spacecraft using the pendulum and cables to create artificial gravity got me thinking about this: What about a spacecraft that uses cables, reaction wheels, and winches to deorbit space junk like a yo-yo? All delta V lost by the target craft, is gained by the operational craft, so it starts low, and keeps throwing things down into atmo, while raising itself to it's next useful orbit. Obviously there isn't enough delta V to change from polar to equatorial or anything crazy like that, but are there enough satellites in similar orbits that a mechanism like this could work?
So here's an interesting idea to work on. What if instead of throttling an engine with the combustion products, we do it with the physical dimensions of the engine itself? Could we, for instance, create a variable-geometry rocket nozzle and throat that would change the amount of thrust for a given amount of propellant burned?
This would take a lot of time and such, I know, and it would be very complex, but in some applications it could be very useful. You could glue one of these to the bottom of a solid rocket motor to have a variable-thrust SRB. The nozzle could also adapt itself to atmosphere pressure, so you don't need separate ground and space engines; this would allow you to take less engines, less weight, less complexity in the plumbing and procedure. A simple PID controller could automatically modulate the engine geometry to get the highest possible ISP or thrust for a given situation.
I think that would be possible with aero spikes.
Similar to the cones on the hybrid engines of the "Black Bird" where the cone is pushed forward or backwards to decrease or increase the flow.
I'm no scientist but that _could_ work... but it takes brain power i don't possess.
Good luck with the heat... just saying 🗿
This is one person apart from Dustin from smarter everyday and everyday astronaunt, i would like to win the dear moon competiotion. They are most deserving of it!
`those 3 together would also make the most comprehencable understanding of the whole experience aka take everyone into space :P
Scott Manley: What training program doesn't teach you
Yeah, I would love to see the dynamic between these three on an adventure like that.
Don't forget Matt Lowne's entry lol
It’s “Destin.”
I'm a follower of Jesus Christ myself. Therefore I'm a Christian. So when Christianity gets into this Flat Earth nonsense, it stings because that only hurts us who are genuine believers of Christ. When I see our giant marble and other planets, I just think how awesome God's creation is. Science and God are 100% compatible, so I take comfort in worshiping my Lord and enjoying the wonders of his creation through the lens of science.
Yep, completely agree. Same here.
What makes you skeptical about the safety of the starship landing? Where is your skeptic based upon?
Have you seen Wright brothers' plane, weren't you skeptical about that?
10:26 to 10:44:
"And, first of all I think that argument is bogus because I think if you're, like, a real super badass God, you're going to create a universe that's 17 billion--whatever--56 billion light years across, with hundreds of billions of galaxies and stars and stuff--you're not going to create a tiny disk like this with a dome over it." --Scott Manley
That is the quote of the day.
Scott manley!! LAND SAFE!!!!!
That movie you mention, Stowaway...it wouldn't happen to be inspired by a certain short story written by Tom Godwin, would it? Because if so, that has rather specific implications for its ending. (Meaning, if you look up that short story, you may spoil the movie for yourself, so be warned.)
The Cold Equations?
There’s a lot in common with the cold equations, but there’s a lot of differences.
Whattt?!?! How ??
@Daffa Mutaqin Tetaputra patreons get vids earlier, remember ?
@@nikakramer obviously a time traveler
The problem with start ship is that there is no failure mode that is not catastrophic. I love that someone with influence is saying it.
Hey Scott... Please have more such upload ... Enjoying the amount of knowledge that is being shared !! :)
What do you think about the video Penny Hit the Earth at the Speed of Light
Impossible to accelerate mass to the actual speed of light, so like all things in life, it comes down the the percentages
Hi Mr Manley. From my experience, science and belief in God are in no way mutually exclusive! (9.54 sec)
P.S I've been a believer for decades, met 1000's of Christians, spent 7 years at Seminary and and, and, and have never heard one person ever make any such claim - like never ever!
That was the exact point he was making, yes.
@@Stukov961 l've triple checked what was said and just can't come to any other conclusion. Others can make their opinion.
Forgive the directness, but are you American? This seems to be a problem unique to certain areas of the US for reasons I don't understand well enough. But those same areas, while nominally "Christian," often are the most prone to misinterpretation.
For a better perspective on their non-exclusivity, the youtube channel Sixty Symbols (hosted by Brady Haran) interviewed the head astronomer at Vatican City
@@Xatzimi Hi Lucy. I appreciated your comment. You are very astute in such matters. But while I'm not from the U.S.A l may fit the idea of a fundamental Christian.
@@Xatzimi Fact is, there are many believers trained in astronomy, zoology, etc, and are comfortable in their fundamental skin. Look up "Answers in Genesis", "Young Earth Creation" and "The Science Channel".
Man, Scott, I've watched quite a few flat earth debunkings, but you destroyed them so hard in half a sentence, use that power wisely!
In a plane you have ejector seats, in a lunar module you have more stages, in a helicopter you just crash slower