# Breaking Atmosphere and Sci-Fi Shenanigans



## Tower75 (May 26, 2017)

Hi, all.

A musing, if you will: I was watching _Interstellar_ the other day (my God that film sucks and Chris Nolan needs to be kept away from all movies*), and something was pointed out to me: you need a three-stage Saturn V rocket to get out of the Earth's gravity and reach orbit, but on a planet that has 130% Earth's Gs you can swan up to orbit in a shuttle?

This really got me thinking; in sci-fi I've never really appreciated that you need a rocket to get to orbit. I'm too used to seeing shuttles, or single-seater craft take off and leisurely fly up and break the gravity of a planet. 

I appreciate that we only need rockets _now _and sci-fi is full of SPACE SCIENCE!!1!, but it still got me thinking.

As much as I love defend Star Wars, it's still a bit of a stretch that an X-Wing has enough fuel and power to break orbit, not to mention _nose diving _into Scarif's exosphere; but then we're talking about a franchise where a single-seater craft can murder a planet.

Now that I think of it, I think I can only call on about 2 or 3 works of sci-fi I've read that need rockets to get to orbit, and that's far-future sci-fi, not contemporary time.

As I say, just a musing really. But it's sci-fi after all; we're also meant to believe that Captain Kirk can successfully sleep with a plethora of female aliens from across the galaxy. Funny how the anatomy always... fits.

*Chris Nolan is terrible.


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## Jo Zebedee (May 26, 2017)

That's the wonder and fun of Space Opera.


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## Phyrebrat (May 26, 2017)

The Star Wars craft are blessed with repulsorlift (antigrav) technology which is how I've always gone along with that conceit.

However, I'm not sure if that's canon or not.

I often feel like an odd-one-out on chrons when it comes to science and physics discussions like this (I'm not particularly 'academic' in that area) as I rarely question anything as long as it's presented in a worldbuild-y believable way. I look at an ocean liner and wonder how it can float, or a 737 can even get off the ground but know physics support it. It's a thin line, I know, but I feel blessed by my ignorance because I enjoy so many films that others complain about.

(but certainly not _Prometheus_) 

pH


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## Amelia Faulkner (May 26, 2017)

Tower75 said:


> As I say, just a musing really. But it's sci-fi after all; we're also meant to believe that Captain Kirk can successfully sleep with a plethora of female aliens from across the galaxy. Funny how the anatomy always... fits.



Psshhht, there's always intercrural for when it doesn't fit


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## The Judge (May 26, 2017)

I'm with Phyrebrat on this -- I've no idea why electricity doesn't leak out through wall sockets so I don't question anything in SF, not even the bangs in space.  (Pun re Captain Kirk not intended but now it's there I'm leaving it!)  Patent historical stupidity and anachronistic attitudes etc in fantasy is a different matter, though, so I can sympathise with the wailing and gnashing of teeth from experts when the SF science is all wrong.

However, since this appears to be a general grumble rather than specifically anything to do with how we write our SFs, I don't think it's a GWD matter as such.  So I'll move it over to SFF Lounge, where we can continue grumbling to our hearts content about all kinds of wrongness in films and TV.


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## Nick B (May 26, 2017)

Think about aeroplanes. The take off, therefore defying gravity, some aircraft almost reach space. In order to just go higher, the just need to be 'space proof'. Admitedly, the physics is the same, you just need velocity. That velocity doesn't have to be straight up. 
Escape velocity going straight up, ie not using any lift made by wings, is just over 11km/s. But that is like literaly throwing a rock straight up. Using aerodynamic lift, you can reach almost to space, without making 11km/s. The higher you go though, the harder lift is to generate by aerodynamics, so you then need greater thrust. But you then haven't got the weight of the fuel a rocket needs just to get going, so have a much lighter craft, making the necesary velocity easier to achieve.

Also, as PB said, scifi science and technology.


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## Tower75 (May 26, 2017)

In conclusion: space shenanigans?


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## Lumens (May 26, 2017)

I agree on Nolan, although I thought Interstellar was one of his better movies. Inception did frustrate me a fair lot becaue of its poor interpretation of dreaming. But that is not why I dislike Nolan as a film maker. I think he is talented but still does not deliver, and that is worse than just being bad. Tarantino is the boss of this, unable to tell a story without getting hung up in trivial "cool" details.

Scifi does not have to be correct though. As long as there is an internal cohesion to the world in the movie, I'm fine with it. There is a story to be told, so some short cuts and freedoms have to be allowed. Interstellar passes on the science for me.


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## Toby Frost (May 26, 2017)

I agree with Phyrebrat, too. Unless it's glaringly stupid, to the point where it doesn't fit the logic of the story, I'm fine with it.


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## Randy M. (May 26, 2017)

Phyrebrat said:


> The Star Wars craft are blessed with repulsorlift (antigrav) technology which is how I've always gone along with that conceit.
> 
> However, I'm not sure if that's canon or not.
> 
> ...



I think this discussion circles around "the willing suspension of disbelief." Phyrebrat makes a good point: If it's not inconsistent with the world of the story, or if a good story otherwise requests you to make a concession or two, the author is supporting and helping along that suspension. When the story demands time and again that you suspend disbelief (and maybe not just on issues of science and technology, but also on human behavior and interactions) then the story's pay-off may not justify the effort.

Some of us may even agree on stories that don't justify the pay-off, but maybe this perception ends up being subjective and highly individual much of the time.


Randy M.


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## Tower75 (May 26, 2017)

I agree with the points about the consistency of the story. I'm happy to let it go that a shuttle can stroll on up and break atmo; I'm not a scientist and I don't know anything about space fight; it was just a thought that occurred to me and genuinely made me think, "wow, I've never thought about that before."

It's weird what we're willing to suspend believe on, isn't it? I mean, in _The Martian _people are happy to accept that Matt Damon (everybody "MAAATT DAAAMAN!") can live by himself on Mars for 2 years but I've read a review where someone took issue that he can grown potatoes on Mars in shallow soil.

I'm as guilty as anyone on this. You tell me that the protagonist's ship has an FTL drive that jumps through time and space and different realities and that they have a robot partner from the future and I'm like: "sure, seems legit." But make a mistake about guns and the inner brat in me flares up with a big nasally "Eh, actually!" (I target shoot, which might explain that.)


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## Venusian Broon (May 27, 2017)

Being slightly contrarian to the general musings here...

Firstly I must make it clear I haven't watched _Interstellar. _However I do believe it was 'sold' on its scientific accuracy, in that physicist Kip Thorne (big in relativity circles - so lots of cred) was involved in making the initial story and was heavily involved as consultant.

It wasn't sold as space opera. Hence if you go in expecting hard SF and it gets things wrong then I think it's alright to point that out as a criticism. However I find that such plot holes are usually inconsequential for enjoyment (or not ) of the plot.

I might try and see if I can watch it soon, but I understand that in the scene you are talking about they are trying to take off from a planet that is orbiting a huge black hole, and I believe Kip Thorne has made mutterings that they used 'slingshot' from other massive objects in the vicinity...(or some other handwavium )

As for space opera, it's partly fantasy anyway, so really anything goes in many respects. Taking _Star Wars_ as the prime example, I mean they aren't even internally consistent with their own makey-up stuff, never mind our current understanding of physics. I'd always recommend leaving logic to one side to just enjoy the Star Wars universe


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## EJDeBrun (May 27, 2017)

_Intersteller_ didn't bother me half as much as _Gravity_ when it comes to the physics of space. I just cannot stop rolling my eyes when it came to the very dramatic George Clooney death. With a movie that was hailed as being so big on the science of things, they certainly f-ed it up at that junction. If his momentum stopped through the tension of the rope, there was no way he was going to get flung into outer space and into the sun. Inertia! It's like, the most basic of basic laws.

*ahem* Rant Over.

I'm an incredibly annoying watcher when it comes to things like this, especially as I  participated in a space settlement course in high school (we even got to stay at NASA for the finals in Cape Canaveral) and also because I took a one off university physics class called "Search for Life in the Universe" (so useful). The one thing you take away from those experiences is how to deal with certain physical aspects of getting into and living in outer space. And since I'm writing a "hard" SF novel now, I've only studied things more. Of course everyone cheats. You have to! Reading about someone waiting 50 light years to talk each other gets pretty boring fast, but you have to cheat in a realistic way. (Ansible!)

So yea, believabiilty vs reality is always something you're dancing with when you're talking about SF and Fantasy. Star Wars as sound in space. Star Trek does not. Whatever you choose has to be the same over time. And that comes down to setting and consistency, since everything written or filmed in SF and Fantasy are always classified as "fiction".

I can tolerate a certain amount of physical unrealism so long as 1) it's minor and 2) it's not like, the CORE basis of your science (Gravity, the court finds you guilty!) But anything further than that and I start gnashing my teeth.

PS: in case anyone is interested, they are working on a lot of space going vehicles that do not require rocket technologies and there is a lot potential in ionic space drives. Someone came up with a realistic engine that can take us up to light speed on very little power. Also a lot of advancements in teleportation! But we're talking at atom size and the amount of energy required is MASSIVE. (I swear I'm not a space nerd. I actually prefer biology as a science of study.)


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## Lumens (May 27, 2017)

Gravity annoyed me so much I gave up watching it.


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## EJDeBrun (May 27, 2017)

Right? It's like, the ultimate playbook of how NOT to mess with physics if you want it to be believable.


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## Tower75 (May 30, 2017)

So, George Clooney dies then? To be fair, I'd steered clear of Gravity as I've heard nothing good about it since its release.


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## EJDeBrun (May 30, 2017)

Not my intention to spoil it so I'll explain here:



Spoiler



George Cloony's character's death is the cornerstone of the story where the MC has to survive "alone" but his death was incredibly contrived. They were connected at by a cord and had a cosmic accident that sent them flinging out into space. Sandra Bullock's character manages to grip the station in time to stop her momentum and the cord holds tight to stop Clooney too. But then they break physics and have his force "act" like it was going to pull her away too, so he "sacrifices" himself by severing the cord so that only he gets sent out to space. But if she already stopped his momentum in 0 gravity, there is no force to send him out anymore. It was so stupid.


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## Stuart Suffel (May 31, 2017)

Re Inception and Interstellar , yup, both complete nonsense concept wise - pure smoke n mirrors.
Nice cinematography in both though.


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## TheDustyZebra (May 31, 2017)

Nick B said:


> Think about aeroplanes. The take off, therefore defying gravity, some aircraft almost reach space. In order to just go higher, the just need to be 'space proof'. Admitedly, the physics is the same, you just need velocity. That velocity doesn't have to be straight up.
> Escape velocity going straight up, ie not using any lift made by wings, is just over 11km/s. But that is like literaly throwing a rock straight up. Using aerodynamic lift, you can reach almost to space, without making 11km/s. The higher you go though, the harder lift is to generate by aerodynamics, so you then need greater thrust. But you then haven't got the weight of the fuel a rocket needs just to get going, so have a much lighter craft, making the necesary velocity easier to achieve.
> 
> Also, as PB said, scifi science and technology.



Now, see, I was going to suggest something to this effect, but I know nothing, so it would have just looked stupid. I'm glad somebody knowledgeable came along and said it first.


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## Vladd67 (May 31, 2017)




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## HareBrain (Jun 2, 2017)

Nick B said:


> Think about aeroplanes. The take off, therefore defying gravity, some aircraft almost reach space. In order to just go higher, the just need to be 'space proof'. Admitedly, the physics is the same, you just need velocity. That velocity doesn't have to be straight up.
> Escape velocity going straight up, ie not using any lift made by wings, is just over 11km/s. But that is like literaly throwing a rock straight up. Using aerodynamic lift, you can reach almost to space, without making 11km/s. The higher you go though, the harder lift is to generate by aerodynamics, so you then need greater thrust. But you then haven't got the weight of the fuel a rocket needs just to get going, so have a much lighter craft, making the necesary velocity easier to achieve.



Saw this in the news today -- gigantic (two-hulled!) aircraft taking the satellite almost to space, then a rocket doing the final bit.

Microsoft co-founder unveils world's biggest plane


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## Tower75 (Jun 2, 2017)

See! We live in the friggin' future. Where's my jetpack!?


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## Nick B (Jun 2, 2017)

HareBrain said:


> Saw this in the news today -- gigantic (two-hulled!) aircraft taking the satellite almost to space, then a rocket doing the final bit.
> 
> Microsoft co-founder unveils world's biggest plane



Yeah, I saw this on Prof. Brian Cox's feed. Huge twin hulled plane. I think the stole the idea from the alien vessel in Primordial tbh. Thieving gits.


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## Ursa major (Jun 2, 2017)

At least they didn't steal the craft (and fuel) from _The Mouse on the Moon_.


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## WaylanderToo (Jun 2, 2017)

Lumens said:


> I agree on Nolan, although I thought Interstellar was one of his better movies. Inception did frustrate me a fair lot because of its poor interpretation of dreaming. But that is not why I dislike Nolan as a film maker. I think he is talented but still does not deliver, and that is worse than just being bad. Tarantino is the boss of this, unable to tell a story without getting hung up in trivial "cool" details.
> 
> Scifi does not have to be correct though. As long as there is an internal cohesion to the world in the movie, I'm fine with it. There is a story to be told, so some short cuts and freedoms have to be allowed. Interstellar passes on the science for me.




glad I'm not the only one! Nolan is currently in credit (100% thanks to Bats), QT... wow what can I say? I really enjoyed Django, Jackie Brown was ok and Pulp was good otherwise


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## Tower75 (Jun 2, 2017)

WaylanderToo said:


> glad I'm not the only one! Nolan is currently in credit (100% thanks to Bats), QT... wow what can I say? I really enjoyed Django, Jackie Brown was ok and Pulp was good otherwise



I do not recognise Nolan's batmen films as Batman movies.

Nolan needs to be kept away from movies and we need to stop this prescient of watching his stuff; it just bolsters the belief that he is good.


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## Nick B (Jun 2, 2017)

I thought Nolan's Batman films were the best Batman has ever been. I liked Inception and Interstellar (apart from the crap ending).


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## Lumens (Jun 2, 2017)

For the record, I don't think Nolan is a bad fim maker, I think his films fall short too often, like they weren't thought through, or he gave up making it as good as he possibly could. It's strange to me, because he seems to have all the right talents. The overall stories are good, cinematography is excellent, and cast too. I just can't put my finger on it, but I don't believe his movies - they don't lead me on. Maybe I'm just being too critical.

Memento is an exception to that. I loved it.


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## Mirannan (Jun 2, 2017)

Explanation follows; I don't want to sound condescending, sorry if I do.

The biggest issue in a rocket is exhaust velocity, because higher exhaust velocity means less propellant (not the same as fuel; I'll get to that) used to get a given change in velocity. And the reason for that is the law of conservation of momentum, coupled with Newton's Third. Higher exhaust velocity can be achieved in two ways, in a rocket; higher temperature and, less obviously, lower average molecular weight of the exhaust. This does not apply to non-rocket reaction engines such as mass-drivers and ion engines, BTW.

Incidentally, the nuclear rocket NERVA achieved its impressive results not because it was particularly hot, but because the exhaust was the lightest possible - molecular hydrogen.

It also helps a great deal if the structure of the vehicle is made of light materials compared to their strength.

So if the fictional ships are essentially rockets, they can get to orbit easily for one of three reasons:

1. They are made of very light materials - maybe graphene and/or carbon fibre.
2. They have particularly hot exhaust, which probably means some sort of nuclear fuel because we are already at the limit of energy for chemical reactions used in rockets. Hotter needs a nuclear reaction - or antimatter annihilation, but do you really want an antimatter-powered ship inside your atmosphere?
3. The exhaust is hydrogen or helium, which also means nuclear power.

That's rockets. However, there is a loophole which has already been mentioned. If you can grab some of your propellant from the surrounding air, then you don't have to carry it around and that makes the numbers a lot better. Unfortunately, for velocities typical of space launches this means something like a scramjet (supersonic combustion ramjet) which is difficult to design (not managed yet, AFAIK) and you still need to transition to rocket power when the air gets too thin. Which means, in turn, that the engine will be very complicated and potentially unreliable and heavy, and even more difficult to design, because of that - or you need two engines, also heavy.

Oh, nearly forgot. Difference between propellant and fuel. Actually, so far there has been no practical distinction, but that doesn't always have to be so. Propellant is what you chuck out of the back; fuel is what provides the energy. So in a NERVA nuclear fission rocket, the propellant is hydrogen - probably liquid - but the fuel is fissile, probably uranium (and that probably enriched.)


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## Tower75 (Jun 2, 2017)

How is that any different to my explanation of: space shenanigans?


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## Ursa major (Jun 2, 2017)

So, to summarise: the solution to the one-engine-acting in two modes seems to be the Stratolaunch and its various predecessors, competitors and, one assumes, their successors: one vehicle using one or more engines that need only fuel to be carried on board and a second vehicle with one or more engines that need everything for them to work to be on board.

This will be in a race with those engineering the two-mode engine and the higher thrust nuclear engines (which may have safety issues, including the velocity of their exhausts...).


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## Mirannan (Jun 2, 2017)

Ursa major said:


> So, to summarise: the solution to the one-engine-acting in two modes seems to be the Stratolaunch and its various predecessors, competitors and, one assumes, their successors: one vehicle using one or more engines that need only fuel to be carried on board and a second vehicle with one or more engines that need everything for them to work to be on board.
> 
> This will be in a race with those engineering the two-mode engine and the higher thrust nuclear engines (which may have safety issues, including the velocity of their exhausts...).



Yep. And one more thing regarding high-efficiency, high-thrust engines: Remember the Kzinti Lesson. You really don't want someone you don't absolutely trust to be in charge of a fusion torch ship in atmosphere.


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