Is there accurate information on what a nuke going off in space looks like?

[SomeGuy123]

Between Orion drives and the fact that one would assume a nuclear bomb would be the default weapon in a space scuffle, since there's no biosphere to contaminate, there are a lot of future scenarios where people might set off a nuke.

What would they look like, with minimal gravity and atmosphere to affect their shape?

What about if you self destructed a ship the size of a modern destroyer or cruiser, with a nuke going off inside somewhere?

[Nibb31]

Yes, the Starfish Prime test:

https://en.wikipedia.org/wiki/Starfish_Prime

[RainDreamer]

The Starfish Prime test looks like it is a sun in middle of the night. Rather inspiring and rather scary at the same time. But there were no footage of the explosion in space captured by another satellite or something, it seems.

[Temstar]

It would be just an very intense burst of light, like the flash of a lightning. That's all. Without some medium (like air) to absorb that energy and then graduate release it over a longer time frame in the form of a fireball there's really nothing much to look at.

The bomb fragments does absorb a lot of energy, but those get blown apart at such high velocity that the human eye can't detect them if you are looking at them up close, and from a distance the fragments are too small to be visible.

[ModZero]

2 hours ago, RainDreamer said:

The Starfish Prime test looks like it is a sun in middle of the night. Rather inspiring and rather scary at the same time. But there were no footage of the explosion in space captured by another satellite or something, it seems.

Considering how much damage it caused (and it was just 10km up!), no wonder. The general attitude of nuclear tests was somewhat amusing. I mean, "previous tests were hastily executed"? Who "hastily executes" a nuclear test?

[YNM]

1 hour ago, ModZero said:

Considering how much damage it caused (and it was just 10km up!)...

Wiki stated 400 km. A nuclear explosion 10 km up would've just, like, make some close island unlivable, and some tsunamis I guess ?

Soviet ones.

[ModZero]

40 minutes ago, YNM said:

Wiki stated 400 km. A nuclear explosion 10 km up would've just, like, make some close island unlivable, and some tsunamis I guess ?

Soviet ones.

Oh, I misread! I was actually surprised because I remembered it was far higher up, but decided I must have been wrong. Turns out it was today when I was short of coffee. 

The things you find starting from such pages. I am pretty sure it used to have mentions of this idea in "see also". 

EDIT: first read about Starfish Prime really put a dent in my excitement of Orion drives. Then I've found out even the puny reactors on Russian probes annoy scientists. 

Edited January 6, 2016 by ModZero

[Temstar]

6 minutes ago, ModZero said:

first read about Starfish Prime really put a dent in my excitement of Orion drives.

Well, the Orion bombs (for the small 10m version) have really low yield, 5kt per bomb in space and a lot less in the atmosphere. Where as Starfish Prime exploded a huge 1.4Mt bomb. A full load of 800 bombs for the Orion is "only" 3Mt, or just over two Starfish Prime bombs.

[ModZero]

17 minutes ago, Temstar said:

Well, the Orion bombs (for the small 10m version) have really low yield, 5kt per bomb in space and a lot less in the atmosphere. Where as Starfish Prime exploded a huge 1.4Mt bomb. A full load of 800 bombs for the Orion is "only" 3Mt, or just over two Starfish Prime bombs.

But what we know from project K is that yield isn't directly related to damage – soviets used 300kt and fried a power plant (I suppose the militaries were trying to rush tests before the inevitable ban, because the stuff is hilariously depressing). Of course in deep space it no longer matters, but a "nearby" comsat would likely be quite unhappy about getting a bunch of small EMP pulses. Of course I'd need actual numbers on EMP from small yield nukes, but the lack of such is what put the damper on my enthusiasm. 

EDIT: before anyone writes it - we know why K did more damage - mostly because location matters in more than one way - but that also means location matters in what damage you do to relatively fragile orbital equipment. 

Edited January 6, 2016 by ModZero

[Elthy]

The emp is only happening in high atmosphere. There would be no EMP if you set of a nuke in deep space...

[ModZero]

24 minutes ago, Elthy said:

The emp is only happening in high atmosphere. There would be no EMP if you set of a nuke in deep space...

Except in actual deep space you don't particularly need Orion drives. And EMP is an issue outside of atmosphere – again, even hte tiny reactors on Russian probes caused trouble to scientific satellites in Earth orbit, so it's reasonable to worry about impact of actual detonations. 

As long as we're outside of va belts it shouldn't lead to starfish prime style whackery, but I wouldn't discount the risk of zapping a comsat or a dozen GPS sats. 

[Elthy]

Dont you confuse EMP and radiation? For an EMP you need an atmosphere (and a magenitic field)...

[fredinno]

7 hours ago, ModZero said:

Oh, I misread! I was actually surprised because I remembered it was far higher up, but decided I must have been wrong. Turns out it was today when I was short of coffee. 

The things you find starting from such pages. I am pretty sure it used to have mentions of this idea in "see also". 

EDIT: first read about Starfish Prime really put a dent in my excitement of Orion drives. Then I've found out even the puny reactors on Russian probes annoy scientists. 

What is up with that article? Would destroying the Van Allen even be possible?

11 hours ago, Temstar said:

It would be just an very intense burst of light, like the flash of a lightning. That's all. Without some medium (like air) to absorb that energy and then graduate release it over a longer time frame in the form of a fireball there's really nothing much to look at.

The bomb fragments does absorb a lot of energy, but those get blown apart at such high velocity that the human eye can't detect them if you are looking at them up close, and from a distance the fragments are too small to be visible.

How was the test even photographed?

[ModZero]

2 hours ago, Elthy said:

For an EMP you need an atmosphere (and a magenitic field)...

I assure you EMP doesn't require ether, a magnetic field is necessary for hijinks in starfish prime style (like, trapping charged particles to cause fun times for ages), and radiation itself is also quite a bit of a problem. But anyway, confusing radiation with electromagnetism is, like, yhm, okay, I don't even know where to start explaining this to you. For now I'll just point out that ether was disproven a few years ago. And if you want to find out what happens to electronics in presence of hostile electromagnetic fields full of funky charged particles (y'know, *radiation*), find out why Europa Clipper won't go into orbit around Europa. Spoilers: that might ruin more than just orion drives.

1 hour ago, fredinno said:

How was the test even photographed?

From the ground. Look at the wiki page. The  photos are funky.

EDIT:

1 hour ago, fredinno said:

What is up with that article? Would destroying the Van Allen even be possible?

Theoretically. Get rid of the charged particles and they're gone (until the magnetic fields trap more of them, which could take a long time, I guess). As far as I can tell, nobody treats it particularly seriously.

Edited January 6, 2016 by ModZero

[Elthy]

According to the Wikipedia page about EMPs they are caused by electrons in the higher atmosphere, which are "kicked away" (no idea how to phrase that better) by gamma radiation. Are the spare atoms in vacuum enough for this effect to happen?

[ModZero]

26 minutes ago, Elthy said:

According to the Wikipedia page about EMPs they are caused by electrons in the higher atmosphere, which are "kicked away" (no idea how to phrase that better) by gamma radiation. Are the spare atoms in vacuum enough for this effect to happen?

Specifically charged particles, which are "radiation" (remember, gamma radiation is also a bunch of particles, photons in this case), and while you need some sort of amplification to fry a power plant, you probably don't need all that much to fry a satellite by exciting the electrons inside the satellite itself (or messing with its panels, for example). I am suspicious about using even small nukes near Earth because of reports of interference from pretty weak sources (TOPAZ messed up gamma ray detectors, which we do have quite a few around Earth) and damage from SP which happened high up to satellites orbiting even higher up. Of course, if anything serious were to start happening re Orion, we'd get real numbers and real risks.

EDIT: also, I'm not a physicist, I only used to be reasonably good at basic physics 15 years ago (gosh I'm old), don't treat me much more seriously than Wikipedia, and you shouldn't treat Wikipedia too seriously. But do be suspicious of magical spaceship drives that only got rejected because nobody would understand the true genius of every single space nerd ;-)

Edited January 6, 2016 by ModZero

[K^2]

12 hours ago, ModZero said:

I mean, "previous tests were hastily executed"? Who "hastily executes" a nuclear test?

A superpower suddenly faced with the threat of an ICBM nuclear attack by another superpower during a cold war standoff. When Soviets have launched Gagarin into space in '61, they've demonstrated capability of delivering a nuclear strike without relying on bombers. I don't recall if USSR has made it public at the time, but at least two Vostok rockets were standing ready to deliver nuclear weapons by '62. US needed a way to defend against a nuclear strike, and they were trying every option. Including detonating their own nuke on the path of an incoming missile. Given the sudden emergence of a threat that, at the time, was absolutely impossible to defend against, you can bet these tests were done hastily.

[Elukka]

As people said before, a nuke in clean space would just be a near-instantaneous flash. It's just a flash of electromagnetic radiation - mostly x-rays, some gamma, still enough visible light to blind you.

For Orion and Orion-derived weapons there's actually a bit of a difference because there the radiation is absorbed by a slab of solid propellant. It instantly turns into a very hot and fast-moving plume of plasma. I think it'd be very incandescent owing to its temperature but for the same reason it'll also dissipate very fast. I don't know if it would remain incandescent after bouncing off the pusher. Freeman Dyson reckoned it'd be invisible, but I don't actually see why. It's a significant amount of very hot, glowing matter, and if it persists for even a fraction of a second I'd think you should be able too see it. This is purely an uneducated guess on my part. I'd really like to learn more on this, whether it would be visible and if so what color it might be, because I really don't know.

[PB666]

plasma glows and reactions are not anywhere near complete conversion, somewhere out there gas will be ionized and cool leaving a afterglow. There will be more than just a flash of light. 

[lajoswinkler]

It looks a lot more symmetrical, spherical and more star-like.

 

Also a reminder that no human can truly perceive these fireballs because up until the mushroom cloud (or the ball, in orbit) cools down, they are so bright that looking into them with unshielded eyes would be painful, if not completely blinding. When such bomb explodes over ground, everything around you is blinding white. Victim of the bomb never sees the mushroom cloud. Just light, and incredible heat that sets some things on fire.

The reason why nuclear explosion test footage/images look as if everything is dark except the bomb is not because the bomb is detonated during the night - it's because the camera has been shielded with such dense light attenuation filters so that the explosion itself becomes discernible. If there weren't any filters, the footage would look totally white.

If you look at the Sun through a welding filter (use only the highest grades, 13 or 14) or if you look into a lightbulb fillament like that, you'll see the source only. Everything else will be dark.

Nuclear explosions are so incredibly energetic that a serious fraction of the emitted light is actually purple and UV, but it's so intense that our eyes are saturated and they send "white!" to the brain.

The color of these explosions is often false because the filters used weren't very "neutral dense", so they'd attenuate unevenly, leaving more stuff towards red and gobbling up more towards purple.
That's the case with Castle Bravo test.

 

Here's a footage of the same test made with a slightly different filter.