Outer space effects (52)

1 Name: Sling!myL1/SLing 05/01/08(Sat)17:17 ID:Qi1ZFXtj

All the scifi animes of this sesson that I have seen have noise in outer space. Yeah, I know it's supposed to be more "exciting" this way. Tho if it was me I would skip the sound effects and put music instead.
But what are the real physics?
There should be some air particles in space. Maybe with a special receiver one could catch some noise... or not?
Maybe a directional laser could decode the sound effects?
Or is it "No sound, period."?

What about proximity explosions? Can a nearby explosion affect a close ship at all?

Recoil: when lauching missiles, shouldn't the launcher be thrown backwards, unless the missiles are sent from both sides?

2 Name: Sling!myL1/SLing 05/01/08(Sat)17:19 ID:Qi1ZFXtj

errata: line 1, change sesson/season.

3 Name: !WAHa.06x36 05/01/08(Sat)18:03 ID:Byh77rUM

I am unsure about the possibility of pressure waves in the interstellar medium. Inside a solar system, maybe there'd be enough to transmit sound, if you had a very good receiver.

Reflecting a laser at an angle off a surface is also at least a theoretical way to listen to sounds transmitted through it (I've seen it suggested that this could be used to eavesdrop here on earth - reflect the laser off the window of a room you want to eavesdrop on. I'm not sure if this has ever been done in reality, and considering it'd be top-secret spy stuff, it'd be hard to know anyway.)

An nearby explosion should cause sound inside a spaceship under most circumstances, but the sound would be more from debris and radiation hitting the hull than from any kind of actual sound transmission.

And finally, it depends on the method used to launch the missiles. A missile fired from a launch tube that was open at both ends would cause hardly any recoil. A missile launched from a closed launch tube would cause recoil, as would a missile launched with some sort of cannon to give it an initial acceleration.

4 Name: Sling!myL1/SLing 05/01/10(Mon)13:40 ID:Heaven

Can a nearby explosion affect a ship?
I mean, aside from the debris?

5 Name: !WAHa.06x36 05/01/10(Mon)15:41 ID:E5bmKDvc

A conventional explosion would only create a shockwave of debris.

A nuclear explosion, on the other hand, would create all kinds of trouble. It's been suggested that a nuclear explosion in vacuum would not create much of a visible-light flash, because the visible light is a secondary effect from the interaction of gamma rays with the atmosphere. In the atmosphere, the radiation from the explosion is quickly absorbed by the nearby air, superheating it and causing the actual fireball and explosion.

In vaccuum, there wouldn't be much of an atmosphere to heat up, so the fireball would not be created. However, the gamma rays and ionizing radiation from the explosion would instead propagate freely outwards. When it hits a ship, it would mostly be absorbed by the hull. For a nearby explosion, this would heat up the hull, possibly to quite extreme temperatures. For more distant explosions, the radiation would create strong ionization in the hull, leading to massive currents and rapidly fluctuating magnetic fields, and an EMP pulse that can fry electronics on board.

Well, that's about what I can recall from reading up on this. I seem to recall that military satellites are EMP-hardened for this very reason.

6 Name: Sling!myL1/SLing 05/01/10(Mon)16:48 ID:Heaven

So basically, we shouldn't be seeing exploding ships, but melting ones instead. No billowing smoke, tho debris could be viewed as a kind of "smoke". No, or a minimal flash.

Oh, and laser shots should be invisible. Only the cannon could emit some light when firing.

7 Name: !WAHa.06x36 05/01/10(Mon)21:13 ID:/+PXKXxy

Well, if a ship has chemical rocket engines, it can explode pretty conventionally after being hit. A fission rocket engine could explode if it was somehow able to get clogged. Some sort of fusion drive I don't know about, since nobody's designed one yet.

Weaponized lasers would most likely not be emitting visible light at all, but would more likely be either longer-wavelength (infrared or microwave), or maybe higher (I'm not sure about ultraviolet lasers, but an X-ray laser would be a pretty fearsome weapon, if you could build one.)

A powerful laser firing in air can very well be visible, though, because it ionizes the air it passes through. In space, you wouldn't have that, but debris from the battle might work the same. Actually, I wonder if some sort of cloud of small droplets or particles wouldn't be a good counter-measure against laser weapons...

If you are having a battle in low orbit with nuclear weapons, though, I wonder if it wouldn't look sort of spectacular from the ground, if the weapons are powerful enough to start affecting the ionosphere. High-altitude nuke tests have caused some quite spectacular effects. See the Starfish Prime test here: http://nuclearweaponarchive.org/Usa/Tests/Dominic.html. Of interest is also the Argus tests: http://nuclearweaponarchive.org/Usa/Tests/Argus.html.

(I love this thread.)

8 Name: !WAHa.06x36 05/01/10(Mon)21:20 ID:/+PXKXxy

The Bluegill and Kingfish tests on that first page are also relevant.

9 Name: dmpk2k!hinhT6kz2E 05/01/10(Mon)23:22 ID:U/4Lko+c

I suspect lasers would not be the weapon of choice in space. There are too many simple countermeasures, you have to be highly accurate, and it requires enormous energy expenditure (with the resulting increase of mass needed on the attacking vehicle).

It's a lot simpler to use shrapnel or high-velocity projectiles. Projectiles can be guided and you don't even need any explosive. Shrapnel would be pretty hard to miss with. Of course if this happened in Earth orbit you'd just have additional extra shit spinning around creating a hazard for future generations.

I suppose you could try substituting plasma for lasers if you want pretty effects, but they'd be even more useless overall. The amount of energy needed would dwarf that of a laser.

10 Name: Sling!myL1/SLing 05/01/11(Tue)02:26 ID:dLpnwG9j

"He had predicted that military significant effects would be produced by injecting charged particles from nuclear explosions into near space to create artificial Van Allen belts. []
The tests essentially confirmed his predictions."
So an atomic blast results in a Van Allen belt. Does this mean that our Van Allen belt is the remain of (an) old atomic blast(s) in space? ^^;

11 Name: Sling!myL1/SLing 05/01/11(Tue)02:34 ID:dLpnwG9j

"Since the shot occurred essentialy above the atmosphere, a luminous fireball was not formed. Instead observers on the island at the moment of detonation saw a green and blue circular region surrounded by a blood red ring. This faded in less than a minute, and blue-green streamers and pink striations developed that lasted half an hour."
Green, blue, red... it's RGB, take cover!
"Essentialy above the atmosphere", meaning "not out of".
And no description of the Argus effects. Does this mean the Argus effects were fully invisible but by the instruments?

12 Name: Sling!myL1/SLing 05/01/11(Tue)02:42 ID:dLpnwG9j


>Some sort of fusion drive I don't know about, since nobody's designed one yet.

Supposedly fusion reactors are safer, they just stop working when there is no more input. No more Tchernobyl with a fusion reactor, they say.

13 Name: !WAHa.06x36 05/01/11(Tue)13:30 ID:E5bmKDvc


Our Van Allen belts are solar wind particles trapped by the Earth's magnetic fields. If you want to call the sun an atomic blast, then sure. The solar wind consists of various charged particles (mainly protons, if I recall correctly). It's similar to, but not quite the same, as the ionizing radiation from a nuclear explosion. Incidentially, passing through the Van Allen belts in a spaceship is no fun, because the solar wind particles are just as dangerous as your usual radiation, and there's quite a lot of them there.


I'm not sure about the Argus tests. I think they were a lot more secretive, for one. And the yields were tiny compared to the Starfish Prime shot - 1.7 kt vs. 1450 kt. It's interesting to note that such a small explosion as 1.7kt was enough to create artificial Van Allen belts measurable from the ground. A large explosion would create pretty signficant effects, no doubt.


For a reactor, yes, but a spaceship drive would likely be of a very different design. There are workable designs for fission-powered rockets, but nobody's worked out how to make a fusion rocket yet. So it's hard to say how it would behave.

14 Name: !WAHa.06x36 05/01/11(Tue)13:36 ID:E5bmKDvc


Oh wait, that was Checkmate, which they say was 60kt. Still, some 35 times more than the Argus tests.

15 Name: !WAHa.06x36 05/01/11(Tue)13:40 ID:E5bmKDvc

I also thought of another effect, that is hinted at by these descriptions of high-altitude tests: The alpha and beta particles emitted from the explosion would be moving at high speeds through the earth's magnetic field, and charged particles being deflected by a magnetic field will emit light. It would be a fairly weak and strange light, but that might be what some of those glows and auroras described are.

16 Name: !WAHa.06x36 05/01/11(Tue)14:11 ID:E5bmKDvc


Apparently you weren't the only one with that idea:


> Interesting historical note: When Explorer I and III first identified the Van
> Allen belts, an initial theory was that they WERE artificial, the results of
> undetected Soviet nuclear tests in space. Van Allen's team eventually (by May
> '58) satisfied themselves that the makeup of the belts didn't fit the expected
> results of such an event, and the belts were announced (correctly) as the
> discovery of a new natural phenomenon.

17 Name: Sling!myL1/SLing 05/01/11(Tue)15:13 ID:srtUDBhj

This is wacky. Venus doesn't have any magnetosphere, Mars' one is spotty at best, bur Earth has two Van Allen belts.

>Van Allen's team eventually satisfied themselves that the makeup of the belts didn't fit the expected results of such an event,

The belt is full of all kind of perticles, I don't get how they came to the conclusion that it was not nuclear.

18 Name: Sling!myL1/SLing 05/01/11(Tue)15:14 ID:srtUDBhj

>>17 errata: perticles/particles

19 Name: !WAHa.06x36 05/01/11(Tue)15:26 ID:2WCeiP4k


A nuclear explosion would create a very specific set of particles, namely alpha (ionized helium nuclei) and beta (electrons and positrons). The Van Allen belts would contain a lot of protons, which are not produced by the reactions in a nuclear explosion. Well, that's my guess, anyway.

20 Name: Sling!myL1/SLing 05/01/11(Tue)17:41 ID:srtUDBhj

How to bust all satellites:
"on July 9, 1962, when the Defense Atomic Support Agency (DASA) and the Atomic Energy Commission (AEC) exploded a hydrogen bomb (a project code-named Starfish) in the inner belt region. The bomb created an intense belt of MeV electrons which among other things damaged the solar arrays of satellites and caused three of them to fail soon afterwards. "
The eeediots! ^^;

21 Name: Sling!myL1/SLing 05/01/11(Tue)18:11 ID:srtUDBhj

The inner belt is indeed mostly protons, but the outer belt has alphas and electrons. Suspicious! :)
Tho, if it has been nuclear it should have decayed and vanished long ago.

22 Post deleted.

23 Name: Random Anime Otaku : 2007-11-06 08:43 ID:Heaven

Extremely old and tired hoax.

24 Name: Random Anime Otaku : 2007-11-07 00:14 ID:TJFphV0A

I think filmmakers lack imagination when it comes to sound.
Seems everyone making a war film, even when it's supposed to be realistic, likes to put in bullets whizzing or sSSSing as if they were subsonic.

all bullets fired after 1885 should go CRACK and SNAP when they fly overhead, much more exiting IMO, and authentic.

Also, for explosions in space, You need some kind of sound, but it could be low-frequency shock type sounds, as if it was the sound of the shock/particles vibrating off of the inside of the spacecraft, even if that's physically dubious. Silent explosions I think can be pretty frightening/exiting, especially if they're well rendered. Explosions in space should be full of visible expanding gases, like ghost-like forms stretching out like hands, the shrapnel/particles flying out would be extremely dangerous, capable of reaching sickening speeds and tearing up any armor they collide with.

25 Name: Sling!XD/uSlingU : 2007-11-07 01:29 ID:KWvuOFZr

I just watched Gundam00 ep5, and one guy says that as the station is at 10,000 km there is still gravity so the girl should be careful not to fall else she would drop to Earth. (Of course the girl had to trip and fall, and is saved by her safety line...)

How much gravity is there at 10,000 km?
The ISS is at 330 km and they have weightlessness (1x10-6 G) already. So I can't believe there's any significant Earth gravity at 10,000 km...

26 Name: Random Anime Otaku : 2007-11-07 03:43 ID:Heaven

If there's gravity at 10,000 km it's REALLY slow.

27 Name: Random Anime Otaku : 2007-11-07 05:33 ID:Heaven


I think it would depend on the planet.

A bigger planet might have a much stronger pull at that altitude, but in the show I guess it was Earth right?

28 Name: Sling!XD/uSlingU : 2007-11-07 13:11 ID:KWvuOFZr

>>27 Yeah, Earth.
I think the physics in Gundam are: there's gravity in weightlessness, but it has a delay. First one floats, then "gravity kicks in" and one lands softly to the ground/floor.

As far as I know, in real life one could die of hunger/thirst if one was alone in a space station and stuck between walls and out of reach of wall handles. There's some gravity mass from the station itself but it should be negligible.

29 Name: Random Anime Otaku : 2007-11-07 15:17 ID:NeZ4bq4n

The gravity on the ISS is pretty much the same as on Earth. 10000 km is about 16000 km away from the center of the earth, to compare with 6000 km at the surface, meaning that it's about (6/16)^2 of normal gravity, meaning about 15%.

However, the ISS is in free fall. It's constantly falling as it orbits the Earth, which cancels out the gravitational pull, and thus you are essentially weightless on the ISS. I did not watch Gundam, so I don't know the situation there, but: If the station is in orbit at 10000km, one would be weightless on board. If it is stuck to something like a space elevator, gravity would be 14%, but there would also be a counteracting centrifugal force, which would lessen that number, but it would not be 0.

30 Name: Random Anime Otaku : 2007-11-07 15:18 ID:Heaven

(Ignore the fact that I confuse the numbers 14 and 15.)

31 Name: Sling!XD/uSlingU : 2007-11-07 17:34 ID:KWvuOFZr

>>29 Yeah, in that Gundam episode they were at the top of a space elevator/orbital tower.

32 Name: Sling!XD/uSlingU : 2007-11-07 20:01 ID:KWvuOFZr

About the centrifugal force in an orbital tower, shouldn't it be that the people at the top are to walk upside down in the station?
Too little centrifugal force and the tower collapses. So a little more force would be desired, meaning the gravity is pointing toward the reverse from Earth's location. The risk should be to not fall off toward outer space, not to fall toward Earth.

33 Name: Random Anime Otaku : 2007-11-07 20:19 ID:Heaven


Right, there would be weightlessness at the geostationary orbit point, which is at 36000km, and an outwards-acting centrifugal force anywhere further out. The standard design calls for some kind of anchor, like an asteroid, some distance out past geostationary that lifts the whole structure.

But 10000km is far below geostationary, so you still get gravity directed torwards the Earth.

34 Name: Sling!XD/uSlingU : 2007-11-07 22:12 ID:KWvuOFZr

>>33 But if I swing a bucket full of water around, the water stays in the bucket. If there is a hole in my bucket, the water will spray out, not in. Shouldn't it be the same for an orbital tower?

35 Name: Random Anime Otaku : 2007-11-08 02:51 ID:cv7HyEeJ

Geostationary still gets gravity directed towards the Earth, the only difference is that the satellite moves at the same angular velocity as earth's spin, so it appears to be stationary whereas it's really orbiting just like any other satellite.

36 Name: Sling!XD/uSlingU : 2007-11-08 04:24 ID:KWvuOFZr

It would "make sense" to have gravity up there if the tower was fixed, unmoving, like a big skyscraper. But the Earth is in rotation, and that would mess up the giant skyscraper pretty badly. I think this is the mistake the Gundam00 writers are making.

37 Name: Random Anime Otaku : 2007-11-08 14:06 ID:dr7kmLgw


Remember, with an orbital tower, you have two forces: Gravity working inwards and centrifugal working outwards. Gravity gets stronger further in, while centrifugal gets stronger further out. They balance exactly at the geostationary orbit point, which is at 36000km.

So the Gundam writers got it right: 10000km is closer to the Earth than the balance point, and thus the sum of the forces is still pointed towards Earth there. Further out from geostationary, for instance at 50000km, the centrifugal force is stronger, and things you let go of would be flung outwards.

38 Name: Sling!XD/uSlingU : 2007-11-08 15:47 ID:KWvuOFZr

>>37 I see.

39 Name: Sling!XD/uSlingU : 2007-11-08 15:59 ID:KWvuOFZr

But then, the orbital tower should collapse under its own weight.

40 Name: Random Anime Otaku : 2007-11-08 18:31 ID:Heaven


That is why you have the huge anchor (such as an asteroid) outside the geostationary point. It pulls the whole structure up.

41 Name: Random Anime Otaku : 2007-11-08 18:37 ID:Heaven

A helpful illustration: http://www.redcolony.com/pics/news/Space_elevator_structural_diagram.jpg

At the "climber", the net force is directed towards Earth, but smaller than normal gravity. At the center of mass/geosynchronous point, the net force is zero and you are weightless, and at the counterweight, you'd be flung outwards.

42 Name: Sling!XD/uSlingU : 2007-11-08 20:39 ID:KWvuOFZr

>>40>>41 Yes, that I understood. But the Gundam elevator stops at 10,000km, I haven't seen any anchor in the anime (unless they consider the array of solar panels around the top tower to be the weight). The only way I can see to get it to stay up there at 10k km is by using rockets. Maybe diverting some of the solar energy to create compressed gas to push it up.

43 Name: Sling!XD/uSlingU : 2007-11-08 21:15 ID:KWvuOFZr

Ah, 'found this:
"In Menclave's subs they say that some sort of magnetic fluid that circulates around the station helps keep it in orbit"

44 Name: Random Anime Otaku : 2007-11-09 14:16 ID:Heaven

Oh, if it stops at 10000km, that is pretty strange.

Seems a stupid decision to make. You could get a lot of milage out of a realistic design in a war show like Gundam, because you'd have a weak point that needs to be defended, namely the counterweight.

45 Name: Sling!XD/uSlingU : 2007-11-09 16:31 ID:KWvuOFZr

The whole orbital tower concept doesn't make sense. The idea in Gundam00 is that the fossil fuels are gone so the world turned to solar power from space. The superpowers made three(!) orbital towers, and are now controlling the world energy. Those towers reportedly use microwaves to beam down the electricity... why even bother to build a tower? Just beam down the energy directly using those microwaves and a station on the ground to collect. As added war "bonus" they could even fry away their enemies by diverting the beam elsewhere once in a while.

46 Name: Random Anime Otaku : 2007-11-14 11:02 ID:9HcqOAbA

Space elevators are silly, You could probably build a large space station (Don't even need that if you've got a low gravity moon) and a giant railgun on a mountain for 10% of the cost and materials required for one.

A lot of useful stuff here:

47 Name: Random Anime Otaku : 2007-11-14 12:47 ID:9HcqOAbA

Oh, And as to the visibility of lasers, I got to see one of the Tactical High-Energy Lasers the US Military is working on tested a couple years back, I didn't note any visible light but when we watched the videos in either IR or NV (I forget witch), We did see beam of light show up and hit the rocket.

48 Name: Random Anime Otaku : 2007-11-14 21:59 ID:Heaven

>>46 It's probably also safer. Cut off the counterweight for the elevator and that's a whole lotta spaghetti wrapping itself around the Earth.

49 Name: Random Anime Otaku : 2007-11-15 23:57 ID:Heaven


It is generally estimated the cable would burn up when hitting the atmosphere.

50 Name: Random Anime Otaku : 2007-11-19 18:31 ID:Heaven

A burning spaguetti wrapping itself around the earth. Now that's a creepy mental image =)

51 Name: Random Anime Otaku : 2007-11-20 00:39 ID:Heaven

There was a similar idea in a Ben Bova book I read a while back called Mercury, IIRC it has something to do with solar wind hitting the ionosphere and generating static electricity.

52 Name: Random Anime Otaku : 2007-12-11 19:01 ID:o59EiwEi

You would hear anything that is touching the camera, and nothing that isn't. Therefore indoor views are bettar.

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