Is Science Fiction Losing Its Charm Due to Unrealistic Space Travel?

[Ryan_m_b]

(And it only has to patrol between areas of interest and act if necessary, otherwise its simple presence is threatening to bad guys. At first level i think about an operational area of Earth's orbit or Earth to Moon.)

Space is big. Patrolling between areas of interest is at best going to take days (Earth-Moon system) and at worse years. There is no point sending a craft on a continual loop between interesting locations on the off chance that during its months/year long round trip something might happen at just the right moment for it to be around to help. This is why the idea of patrolling makes no sense.

Similarly if it takes years to get anywhere then by the time you get there the thing to came for is likely to be over. If military presence was deemed to be a necessity then it's likely to be a permanent, on site feature rather than something that is moved around like today.

Fascinating! I'll have to read up on this. Would you basically need multiple neutrino detectors arranged at distance from each other, in order to pick up relative differences and calculate the position of the source? Or can a single detector obtain the direction of the source?

*goes off to wikipedia...*

I'm not sure, I'm guessing several.

The thing about space combat is that it is very difficult to hide anything. Even with today's technology tiny things can be tracked.

Quite, it's even easier when the object in question is several hundred degrees hotter than its surroundings http://www.projectrho.com/public_html/rocket/spacewardetect.php#id--There_Ain't_No_Stealth_In_Space

My guess is that any kind of space combat would be so fast and secretive that it would all be done by computers. There would be no human involvement at all. You would be flying along and either suddenly cease to exist or get a computer message that you just won.

Any ordinary spaceship would have a tiny crew that was bored as could be, just waiting for something to repair. Any sort of warship would be completely unmanned.

It really depends on what we mean by space combat. Curiously we don't generalise for anything else, why space?

 

[GTOM]

What about orbital patrol? The ranges are smaller.

I think about the descandants of this : http://en.wikipedia.org/wiki/Boeing_X-37

(Ok, than no frigates just destroyers with Earth to Moon range...)

I would be still curious : if we can already see distant planets, why USA sends drones to unfriendly countries, where they are shot down and hacked up? Why can't they solve recon with a big orbital scope? I don't think a RQ-170 Sentinel could enter into buildings, overhear conversations...
Is it because the distortion of the atmosphere, or what?Otherwise I can agree that short range craft can be remote controlled, but i sure wouldn't trust decision making to compus (at least... ). It would be too much temptation to politicans and military leaders.
A drone operator can still feel remorse, guilt.

 

[Ryan_m_b]

What about orbital patrol? The ranges are smaller.

You can drop patrol there and just say orbit unless you want a craft tat burns through all its few a short time after deployment. Otherwise sure.

I think about the descandants of this : http://en.wikipedia.org/wiki/Boeing_X-37

I doubt like this. I'm thinking more along the lines of the international space station with more propulsion and weapons. Not a space plane. You can't dog fight in space and there isn't a role that I can see for a fighter type craft between larger craft and smaller missiles.

I would be still curious : if we can already see distant planets, why USA sends drones to unfriendly countries

Firstly our detection of exoplanets is not by seeing them directly, but by observing the effect they have on their sun. Secondly whilst we can see planets in this system there are things that telescopes can't do that we use probes for. Thirdly what we're talking about in this thread is the detection of spacecraft which would not be done by visual means of the craft itself but by thermal means of it and its exhaust. Lastly satellites in Earth orbit have only a tiny amount of the the surface they can see at anyone time in their orbit (presuming no cloud cover and its day). No nation has so many satellites that they can see any point on Earth at any time so drones are used (amongst other reasons).

 

[GTOM]

"I doubt like this. I'm thinking more along the lines of the international space station with more propulsion and weapons. Not a space plane. You can't dog fight in space and there isn't a role that I can see for a fighter type craft between larger craft and smaller missiles."

I think that depends on exactly what you want to achieve. (And what kind of engine developments can we achieve.)

Ok if you can barely have enough delta-V to reach a certain target and only want to destroy that, yes you use a missile.

If you want to reach multiple targets, you can provide enough delta-V, and maybe not destroy just capture some of them, i see a role for smaller planes.

For example you might want protect your own satellites meant to watch a country, attack the satellites (and anti satellite missile sites) of that country, that means all of them will fly above that country.
Then you can position a squadron of small ones to a low orbit, where they might protect an own satellite at first, bomb a missile site next, then modify orbit to attack an enemy satellite. (They might use the upper stratosphere to modify their vector?)
During this, you might want to keep your precious station on a high orbit, possibly GEO above your country. (if they have the technology to attack it... yes it can defend itself much better than the small ones, but you can afford to lose some of the small ones, while you don't want to endanger a big station)

Or you want to capture a rocket of a crime lord, before it could reach a safe haven.
A missile can't capture a ship, a plane can fire warning shots to it, and only destroy it if absolutely necessary. Ok you might fire a missile and blow it up, if they modify their course, but you sacrifice the missile.
Assuming that fuel will be cheap enough, and there will be cheap methods to get it to orbit (asteroid mine, induction catapult, space elevator from Moon) it is better to sacrifice fuel then missiles, and care about versatility and reusability.
(Well intercontinental ballistic missiles exists for long, there are also high-precision missiles, but attack vehicles are still needed. )

I have a Mohs scale 5 situation in mind.

 

[Ryan_m_b]

You're really underestimating how much all that manoeuvring is going to cost in terms of fuel and energy and therefore mass and therefore thrust. Orbital speed it a hell of a lot faster than anything in atmosphere. You can't just shed that and speed off in other directions. On top of that you should brush up on the basics of orbital mechanics, you can't have a squadron of planes hovering under the orbit of a satellite, at least not without constant thrust. On top of that none of the tasks you mention would be best suited to planes over weaponised satellites.

Regarding capturing a craft that's pretty much impossible. It requires you carefully match velocity and gently dock. Not going to be possible if the other craft doesn't want you too, all they have to do is spin their craft along its axis and you're screwed.

I'm sorry but this isn't moh-5, more like 2. I think you're basing too much of this on science fiction and not science.

This thread has gone on long enough with no development. I suggest we take a break until anyone has something definitive to discuss I.e some actual science to speculate on or some fiction to talk about.

 

[GTOM]

Ok, weaponised reloadable satellites.
I hope this is a development, if not, than sorry, do what you have to do.


Another things : in space there are pretty much radiation. Earth is protected by its magnetic field from the worst things. Could this be a viable method to protect spaceships (colonies) instead of thicker hulls?

 

[Ryan_m_b]

There is research along those lines
http://physicsworld.com/cws/article/news/2008/nov/06/magnetic-shield-could-protect- spacecraft

 

[GTOM]

Thank you.


A bit more about protection and sci-fi : i found a link in this forum, in an experiment they used magnetic fields and lasers to keep particles at one place. When they released them, they drew away that much energy, that they called their state beyond absolute zero...
Is there any chance that this super entropy-less state could be used to create some supersolid armor? (well a bit like to the concept of energy shield)

Second, about induction catapults, mass drivers, coilguns.
What could be the theoretical limit of acceleration, that a simple solid object could withstand without ripped to plasma dust?

So for example, if one would like to take out a meteor, and boost a projectile to 10km/s in order to do it, what could be the minimum length of the coilgun?
(Assuming, with some next generation technology, they can solve power supply, engineering, recoil etc)

 

[Ryan_m_b]

Here is the PF discussion on the topic https://www.physicsforums.com/showthread.php?t=662268.

Re acceleration if it is uniform across the object then the answer is infinite. If not it's down to the material properties of whatever it is made out of. Re length it depends on how fast you're accelerating. Ask in one of the physics forums if you want to learn how to work it out.

 

[GTOM]

Ok, thank you.

(And again, sorry for our previous misunderstainding. :( I should have made it clear that I imagined the orbital craft to operate in a wider orbital belt, so it could observe and attack more, gradually modificating course during turn around the planet, and by capture, i meant, force to surrender by lethal threat. )

 

[Ryan_m_b]

Ok, thank you.

(And again, sorry for our previous misunderstainding. :( I should have made it clear that I imagined the orbital craft to operate in a wider orbital belt, so it could observe and attack more, gradually modificating course during turn around the planet, and by capture, i meant, force to surrender by lethal threat. )

No worries. But do go and look into how orbit works. It's vastly different to any medium on Earth with the speeds, distances and vacuum making zipping around like any terrestrial transport impossible.

 

[GTOM]

I read about orbital mechanics, i think its a must have to SF writers (who want to deal with space).
Yes an inclination change isn't something that can be taken lightly...
Although i saw methods that could make that easier.

1 : scratch the stratosphere, then ascend
2 : take an elliptical path, and change inclination at apophis, where speed is smallest
3 : use recoilles stuff, like magnetic fields in the magnetosphere

I wonder whether magsails could take over rockets, if big acceleration isn't needed?
(Since there arent confirmed progress with anti gravity, space time warp, sails are the only recoilles methods. )

 

[Vierstein]

Moderation note: This thread has been split from another so as not to derail the former thread

I have a hard time enjoying Star Wars anymore because of how those spaceships fly around :(

What you don't like the sound they make in space?

VRROOOOMMM XD

 

[Traz 0]

I'm not sure which of the split threads this belongs in, but ...

Footfall, by Larry Niven and Jerry Pournell had what seemed to me at the time (1985) to be some very well thought out space combat. Human versus alien, where the aliens have superior tech but we have desperation. We launch a supermassive Orion-type carrier ship (from Earth ... Desperate!) accompanied by a fleet of shuttles. The primary weapons used are x-ray lasers pumped by the orion drive. The aliens are dumbfounded by the reckless tactics.

Niven and Pournell are famous for hard SF, and if I recall correctly, Pournell worked on a real life space-based kinetic weapon system which was never deployed (or was it? ;-) ) called Thor or Thads ...

 

[Traz 0]

I just realized that I didn't define the Orion drive. Project Orion was a real life proposal to propel a spacecraft by exploding nuclear bombs behind a pusher plate. I suspect that it would be a bumpy ride ...

 

[ImaLooser]

I just realized that I didn't define the Orion drive. Project Orion was a real life proposal to propel a spacecraft by exploding nuclear bombs behind a pusher plate. I suspect that it would be a bumpy ride ...

I remember that. One of the scientists involved in launching a small chemical prototype said, "This is not nuts, this is supernuts."

 

[Traz 0]

I remember that. One of the scientists involved in launching a small chemical prototype said, "This is not nuts, this is supernuts."

Well, I certainly wouldn't want to live downwind of a surface launch.

As far as a Project Orion space drive, I suppose that its feasibility is partially an engineering problem, and partially political, i. e., who would I trust in possession of hundreds of nukes in space, how they could be secured, etc. Barring an alien invasion or a dino-killer space rock with our name on it, my vote would be, uh, no thanks.

 

[Traz 0]

No worries. But do go and look into how orbit works. It's vastly different to any medium on Earth with the speeds, distances and vacuum making zipping around like any terrestrial transport impossible.

From the Robert Heinlein wiki:

Heinlein himself stated - with obvious pride - that in the days before pocket calculators, he and his wife once worked for several days on a mathmatical equation describing an Earth-Mars rocket orbit, which was then subsumed into a single sentence of the novel Space Cadet.

 

[Ryan_m_b]

From the Robert Heinlein wiki:

Heinlein himself stated - with obvious pride - that in the days before pocket calculators, he and his wife once worked for several days on a mathmatical equation describing an Earth-Mars rocket orbit, which was then subsumed into a single sentence of the novel Space Cadet.

I'm not sure how that applies to the quoted sentence...

 

[Traz 0]

I'm not sure how that applies to the quoted sentence...

and previously (I don't know how to multi quote on my phone):

GTOM said, roughly:

"I read about orbital mechanics, I think it's a must have for science fiction writers ..."

See, my point was, Robert Heinlein, a pretty famous science fiction writer, seems to have agreed with both GTOM and you about orbital mechanics vis a vis SF writing, in a time when doing so took a lot more work.

I thought the thread I was following there was pretty clear ...

 

[Riemann Metric]

Well, I certainly wouldn't want to live downwind of a surface launch.

As far as a Project Orion space drive, I suppose that its feasibility is partially an engineering problem, and partially political, i. e., who would I trust in possession of hundreds of nukes in space, how they could be secured, etc. Barring an alien invasion or a dino-killer space rock with our name on it, my vote would be, uh, no thanks.

I'm sure there are many elegant solutions to space travel than blowing up a bunch of bombs behind a plate to launch a spacecraft at high speed-take solar sails or magnetic acceleration cannons/mass drivers, for instance. The only issues we have with these are slow acceleration+microasteroids vs. tremendous forces and huge momentary accelerations.

 

[Traz 0]

I'm sure there are many elegant solutions to space travel than blowing up a bunch of bombs behind a plate to launch a spacecraft at high speed-take solar sails or magnetic acceleration cannons/mass drivers, for instance. The only issues we have with these are slow acceleration+microasteroids vs. tremendous forces and huge momentary accelerations.

I'm sure there are more elegant solutions too.

In the novel<I> Footfall </I>, the problem to be solved wasn't spaceflight, per se. The invaders had occupied Earth, had surveillance ships in orbit, and a giant, well-protected mothership that was all but invulnerable. Engaging the enemy required a truly massive ship of our own that could sustain a great deal damage from kinetic and directed energy weapons. It also had to be built in secret, on earth, in a hurry, without a research program or orbital construction.

As far as stopping a dino-killer rock in a hurry, it's not inconceivable that we might have to substitute quick and dirty for elegant in certain scenarios. It certainly happens in the real world.

In 1992, I was managing a project to convert a government agency's antiquated applications and data to modern hardware, and there were a number of files that were weird for some reason I can no longer recall. I diagramed as general algorithm that could read any such file and create the data structure and conversion code needed, and gave it to a programmer. Rather than write that application, he looked at the files, found there were only 20 or so unique types, and wrote 20 or so separate programs. I have a strong preference for elegance in all things, and his solution pissed me off. But. The project had been underbid, we were behind schedule, and every day late cost my company money. His way <I> was </I> faster, and assuming we never needed to do the same type of conversion again, better.

Still, I'm not advocating <I> Project Orion</I> as a space travel solution, by any means, and I hope it didn't seem like I was.

 

[Riemann Metric]

Well, who knows...maybe something that seems unorthodox like Project Orion could inspire something that really does work. As it is said, necessity is the mother of invention, and I fear our efforts towards something we think we don't need will be rather negligible until our views change.

 

[lpetrich]

Isaac Asimov, in "Future? Tense!" from From Earth to Heaven described how a science-fiction writer in 1880 might write stories involving cars.

"The automobile came thundering down the stretch, its mighty tires pounding, and its tail assembly switching furiously from side to side, while its flaring foam-flecked air intake seemed rimmed with oil." Then, when the car has finally performed its task of rescuing the girl and confounding the bad guys, it sticks its fuel intake hose into a can of gasoline and quietly fuels itself.

While a car as a mechanical horse seems almost too silly for us to take seriously, lots of visual-media science fiction has similar absurdities about its spaceships.

I recall when Gene Roddenberry was once asked about some of them, like never seeing spaceships upside down. He responded that that was to avoid unnerving an Earthbound audience, and that's why explosions in outer space make sounds. A soundless explosion is correct, but it would make many watchers wonder what happened to their TV's' sound.

Some Star Wars battleships look more like they could be floating than flying, with a hull and a superstructure on one side of it, the crewmembers' upward direction.

A lot of the space combat in the Star Wars series looks like it could have come out of WWI and WWII dogfights -- the fighter spaceships behave too much like airplanes.

IA also imagined:

There could be the excitement of a last-minute failure in the framistan and the hero can be described as ingeniously designing a liebestraum out of an old baby carriage at the last minute and cleverly hooking it up to the bispallator in such a way as to mutonate the karrogel.

Some Star Trek episodes are full of that sort of thing, something that some fans and critics have named "treknobabble".

 

[GTOM]

Can we return to recon a little bit?

Ryan you said, that a really big battleship could carry a neutrino detector.
I read that a neutrino can easily go through the entire Earth.
Ok, you can determine whether something with a reactor is close or not, but can you possibly get any accuracy needed to target?

While you can't become invisible in space, how about a smoke screen like application, once you don't need to use the thrusters (you might still be able to do a tiny course change with magnetic fields), sorround your ship with black canvas, metallic nets, chaff? You don't have to be in the middle of this. Yes they will know roughly where you are, but i almost hit it is unsatisfactory... Probably you don't have a second chance to fire, or offer a barrage strong enough.
The concealed one could still see with small outside probes.

Also planetary defences have much better options to conceal a cannon, or orbital craft can redirect its waste heat toward the planet.

 

[Ryan_m_b]

Ryan you said, that a really big battleship could carry a neutrino detector.
I read that a neutrino can easily go through the entire Earth.
Ok, you can determine whether something with a reactor is close or not, but can you possibly get any accuracy needed to target?

Sure neutrinos fly through the Earth and a lot more. But detectors can snatch a tiny percentage of them because a very small number will, statistically speaking, hit an atom.

While you can't become invisible in space, how about a smoke screen like application, once you don't need to use the thrusters (you might still be able to do a tiny course change with magnetic fields), sorround your ship with black canvas, metallic nets, chaff? You don't have to be in the middle of this. Yes they will know roughly where you are, but i almost hit it is unsatisfactory... Probably you don't have a second chance to fire, or offer a barrage strong enough.
The concealed one could still see with small outside probes.

Also planetary defences have much better options to conceal a cannon, or orbital craft can redirect its waste heat toward the planet.

There's no stealth in space because your craft will be vastly hotter than the background. If you've got a power source like a nuclear reactor it means that your craft is going to have a spot in it hundreds of degrees hot. Even just at zero degrees C you will be hundreds of degrees hotter than the background.

This is a good article on the subject: http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth

 

[GTOM]

"This is a good article on the subject: http://www.projectrho.com/public_htm...php#nostealth"

I read it already. But i didnt intend to hide my vector.

"sorround your ship with black canvas, metallic nets, chaff? You don't have to be in the middle of this."
"Yes they will know ROUGHLY where you are, but i almost hit it is unsatisfactory... "

"If you've got a power source like a nuclear reactor it means that your craft is going to have a spot in it hundreds of degrees hot."

So I sorround the ship with a light weighted, but opaque canvas. It will be heated all around to a pleasent degree. So where is the ship exactly in a large (but light) cube? Where should you aim if you want to actually hit it?

Of course it will the transparent to neutrinos (and i have to send out at least recon stuff communicating with wires).
But putting a neutrino detector to a battleship?
http://en.wikipedia.org/wiki/Sudbury_Neutrino_Observatory
And you have to shield it from your own reactor if you don't run with chem fuel.

Well, I don't really think this is viable, but at least it will be pretty hard to build such a spacecraft .

 

[Ryan_m_b]

So I sorround the ship with a light weighted, but opaque canvas. It will be heated all around to a pleasent degree. So where is the ship exactly in a large (but light) cube? Where should you aim if you want to actually hit it?

Aside from the problem of how do you see where you're going now there are going to be hotspots suggesting where you are. Even if not I can't see you dragging around a big enough canvas than an enemy couldn't just shoot a missile through that has a shaped charged and is smart enough to quickly locate you and explode in that direction.

Of course it will the transparent to neutrinos (and i have to send out at least recon stuff communicating with wires).
But putting a neutrino detector to a battleship?
http://en.wikipedia.org/wiki/Sudbury_Neutrino_Observatory

Lol you're talking about huge military spacecraft with nuclear reactors and you have a problem with fitting a neutrino detector in if you're handwaving away the technical difficulties of the former you should at least be consistent with not handwaving away other difficulties.

Besides which looks like there are efforts to shrink the size of detectors:
http://minnesota.publicradio.org/display/web/2010/07/13/university-of-minnesota-neutrino-detector

 

[GTOM]

" if you're handwaving away the technical difficulties of the former you should at least be consistent with not handwaving away other difficulties."

I carried a tent many times but not a rad suit (shielding from your own reactor).

Otherwise OK i just surrender.
Thanks for the article Ryan, it is always good to read about new developments. :)

 

[GTOM]

" http://www.projectrho.com/public_htm...php#nostealth "

"The maximum range a ship running silent with engines shut down can be detected with current technology is:

Rd = 13.4 * sqrt(A) * T2

where:

Rd = detection range (km)
A = spacecraft projected area (m2 )
T = surface temperature (Kelvin, room temperature is about 285-290 K)

If the ship is a convex shape, its projected area will be roughly one quarter of its surface area."

An example : http://en.wikipedia.org/wiki/Chelyabinsk_meteor

"The United States space agency NASA estimated the diameter of the bolide at about 17–20 m and has revised the mass several times from an initial 7,700 tonnes (7,600 long tons; 8,500 short tons),[10] until reaching a final estimate of 10,000 tonnes"

Ok. Diameter 17m, radius half.

A ~ (17/2)^2*pi ~ 227m2 (*4 /4)

Surface temperature : (average lunar temperature?) 250 K

So Rd = 12 617 655 km...

If i decrease surface temperature to 40K (lunar minimum) it is still 323 026 km, Earth to Moon range.
And they can browse the whole sky in 4 hours...

"The Chelyabinsk meteor was a near-Earth asteroid that entered Earth's atmosphere over Russia on 15 February 2013 at about 09:20 YEKT (03:20 UTC), with an estimated speed of 18.6 km/s "

If i ignore speed gained by Earth'as gravity, just multiply 18,6 with four hours, it is still below that claimed distance.

What did i miss? They missed the meteor, there wasnt last minute warning, please get away from the windows.