Arioch wrote:I doubt very much that you would be able to accurately predict the exact path of a neutron star through our solar system 70 years in advance of the encounter. I don't think it's possible to know the mass of the object to a close enough precision to be able to say with certainty what would happen. The slightest perturbation would significantly alter the interaction of the system, and such perturbations could be introduced deliberately.
A neutron star may only be 20-some km across, but the minimum mass is about 1.4 solar masses, about 1500 times the mass of Jupiter. If you're dealing with an opponent that can meaningfully perturb an object that outmasses the entire solar system, your best bet is to very humbly ask them for forgiveness for whatever it is you did that displeased them so much, since running away or hiding probably isn't going to work.
Otherwise, I really don't see a problem in working out the orbit necessary to place yourself on the far side of Jupiter from the most energetic of the events. The gravitation of the sun is well known, the gravitation of the incoming star is in a fairly narrow range, and probes could easily make precision measurements if there are no conveniently nearby Oort cloud/Kuiper belt objects to observe as they interact with the invader. You also don't have to put the stations in their final orbit 70 years in advance.
...you may have missed the second part of that comment, where Arioch pointed out that the cause of the catastrophe wasn't relevant to the discussion at hand?
"Sometimes it's better to light a flamethrower than to curse the darkness."
Well, depending on the cause of the disaster, you could potentially use the disaster to your benefit. A nova could provide a lot of delta V if you had an appropriately shaped pusher plate.
icekatze wrote:Well, depending on the cause of the disaster, you could potentially use the disaster to your benefit. A nova could provide a lot of delta V if you had an appropriately shaped pusher plate.
That is good lateral thinking. I approve.
That said, such a pusher plate might be more expensive than launching a more conventional craft a few years or even decades earlier.
Absalom wrote:Sorry about the lack of clarity, I was assuming the more extreme threat as well, but with the quirk of building the escape ship from lunar materials instead of terrestrial materials, thanks to very early launches of mining equipment to the Moon via Orions. For bulk materials, it strikes me as a pretty good option (certainly better than asteroids, since you can partially use existing technology, and better than the Earth, since you can launch more easier). This wouldn't prevent Earth launches either.
The data I've been able to find on Lunar minerals suggests that the most common resources would be anorthite (which can be refined into aluminum), iron, calcium (as a byproduct of anorthite refinement), and ilmenite (a resource that can be purified into titanium). Of those four, only the ilmenite and anorthite would be really useful as titanium and aluminum both have high strength for their mass and aluminum is used as fuel for some chemical rockets. Either way the mining will be much easier than the refining and forging. It'll take quite a bit of infrastructure before we can make moon-mines viable, but it still might be a good idea.
The numbers I've seen place oxygen, silicon, and aluminum, in that order, as the most common constituencies of the entire Moon, or at least the visible surface. I don't know that silicon is all that usable as a structural material, but aluminum conceptually is. That having been said, aluminum supposedly has no way to not loose strength over time, so I'd be more inclined to use it for internal components, launch fuel, and initial facilities construction. The "good stuff" is the iron and titanium (primary structural components, until you get time to hunt down a carbon-rich asteroid), generalized regolith (ablative armor), etc. Still, depending on time required, perhaps the aluminum would be the right way to go.
Eluvatar wrote:
icekatze wrote:Well, depending on the cause of the disaster, you could potentially use the disaster to your benefit. A nova could provide a lot of delta V if you had an appropriately shaped pusher plate.
That is good lateral thinking. I approve.
That said, such a pusher plate might be more expensive than launching a more conventional craft a few years or even decades earlier.
icekatze wrote:Well, depending on the cause of the disaster, you could potentially use the disaster to your benefit. A nova could provide a lot of delta V if you had an appropriately shaped pusher plate.
That is good lateral thinking. I approve.
That said, such a pusher plate might be more expensive than launching a more conventional craft a few years or even decades earlier.
Unless you have damned good shielding systems and cooling systems all over the ship, you're still dead. The radiation and heat will go around the pusher plate and will fry and cook/burn anything in the ship. Remember you'll be inside the nova AoE when it goes off. It's being, literally, in the middle of a fusion explosion many orders of magnitude stronger than the most powerful nuclear weapon humanity has ever made.
Absalom wrote:Sorry about the lack of clarity, I was assuming the more extreme threat as well, but with the quirk of building the escape ship from lunar materials instead of terrestrial materials, thanks to very early launches of mining equipment to the Moon via Orions. For bulk materials, it strikes me as a pretty good option (certainly better than asteroids, since you can partially use existing technology, and better than the Earth, since you can launch more easier). This wouldn't prevent Earth launches either.
The data I've been able to find on Lunar minerals suggests that the most common resources would be anorthite (which can be refined into aluminum), iron, calcium (as a byproduct of anorthite refinement), and ilmenite (a resource that can be purified into titanium). Of those four, only the ilmenite and anorthite would be really useful as titanium and aluminum both have high strength for their mass and aluminum is used as fuel for some chemical rockets. Either way the mining will be much easier than the refining and forging. It'll take quite a bit of infrastructure before we can make moon-mines viable, but it still might be a good idea.
The numbers I've seen place oxygen, silicon, and aluminum, in that order, as the most common constituencies of the entire Moon, or at least the visible surface. I don't know that silicon is all that usable as a structural material, but aluminum conceptually is. That having been said, aluminum supposedly has no way to not loose strength over time, so I'd be more inclined to use it for internal components, launch fuel, and initial facilities construction. The "good stuff" is the iron and titanium (primary structural components, until you get time to hunt down a carbon-rich asteroid), generalized regolith (ablative armor), etc. Still, depending on time required, perhaps the aluminum would be the right way to go.
Silicon + oxygen = silica, the primary component of glass fiber. In fact, plain basalt can be spun into fiber that can be used in reasonably high performance composites. Elemental silicon fiber would probably also be pretty good, but I don't know if its strength to weight would be higher than silica. And it's not like you need the oxygen for something else...there's only so much you can breathe.
Calcium's too reactive to use on Earth, but would make a good electrical conductor in vacuum, and alloys might be good structural metals (it's the lightest of the alkali earth metals, lighter than magnesium). You would need a thicker wire gauge than copper to achieve the same conductivity, but IIRC, the mass would be lower. Calcium and oxygen are also components of many ceramics, particularly high-temperature ones.
Waste oxygen could be a useful propellant, if you can keep it from oxidizing your rocket engine. Silicon could be a low-performance but cheap fuel to use with it.
icekatze wrote:Well, depending on the cause of the disaster, you could potentially use the disaster to your benefit. A nova could provide a lot of delta V if you had an appropriately shaped pusher plate.
That is good lateral thinking. I approve.
That said, such a pusher plate might be more expensive than launching a more conventional craft a few years or even decades earlier.
Unless you have damned good shielding systems and cooling systems all over the ship, you're still dead. The radiation and heat will go around the pusher plate and will fry and cook/burn anything in the ship. Remember you'll be inside the nova AoE when it goes off. It's being, literally, in the middle of a fusion explosion many orders of magnitude stronger than the most powerful nuclear weapon humanity has ever made.
joestej wrote:The data I've been able to find on Lunar minerals suggests that the most common resources would be anorthite (which can be refined into aluminum), iron, calcium (as a byproduct of anorthite refinement), and ilmenite (a resource that can be purified into titanium). Of those four, only the ilmenite and anorthite would be really useful as titanium and aluminum both have high strength for their mass and aluminum is used as fuel for some chemical rockets. Either way the mining will be much easier than the refining and forging. It'll take quite a bit of infrastructure before we can make moon-mines viable, but it still might be a good idea.
The numbers I've seen place oxygen, silicon, and aluminum, in that order, as the most common constituencies of the entire Moon, or at least the visible surface. I don't know that silicon is all that usable as a structural material, but aluminum conceptually is. That having been said, aluminum supposedly has no way to not loose strength over time, so I'd be more inclined to use it for internal components, launch fuel, and initial facilities construction. The "good stuff" is the iron and titanium (primary structural components, until you get time to hunt down a carbon-rich asteroid), generalized regolith (ablative armor), etc. Still, depending on time required, perhaps the aluminum would be the right way to go.
Silicon + oxygen = silica, the primary component of glass fiber. In fact, plain basalt can be spun into fiber that can be used in reasonably high performance composites. Elemental silicon fiber would probably also be pretty good, but I don't know if its strength to weight would be higher than silica. And it's not like you need the oxygen for something else...there's only so much you can breathe.
I don't see mention of a binder anywhere in this. I hope you're not proposing iron (melting point) or aluminum (arguing against it due to unavoidable stress-related degradation was the point of that part of the post).
Mjolnir wrote:Calcium's too reactive to use on Earth, but would make a good electrical conductor in vacuum, and alloys might be good structural metals (it's the lightest of the alkali earth metals, lighter than magnesium). You would need a thicker wire gauge than copper to achieve the same conductivity, but IIRC, the mass would be lower. Calcium and oxygen are also components of many ceramics, particularly high-temperature ones.
Waste oxygen could be a useful propellant, if you can keep it from oxidizing your rocket engine. Silicon could be a low-performance but cheap fuel to use with it.
I already mentioned "etc.", though I hadn't considered silicon as a propellant fuel: good idea that answers how to launch from the moon pre-semiconductor purities.
Absalom wrote:I don't see mention of a binder anywhere in this. I hope you're not proposing iron (melting point) or aluminum (arguing against it due to unavoidable stress-related degradation was the point of that part of the post).
No, I was thinking of something more conventional. You need very little binder compared to the amount of reinforcement fiber, you could import it (or the hydrocarbons needed to produce a silicone binder) and still achieve a large gain. Cloth and cables can also be useful without any binder.
icekatze wrote:Well, depending on the cause of the disaster, you could potentially use the disaster to your benefit. A nova could provide a lot of delta V if you had an appropriately shaped pusher plate.
Eluvatar wrote:
Zakharra wrote:
Eluvatar wrote:
That is good lateral thinking. I approve.
That said, such a pusher plate might be more expensive than launching a more conventional craft a few years or even decades earlier.
Unless you have damned good shielding systems and cooling systems all over the ship, you're still dead. The radiation and heat will go around the pusher plate and will fry and cook/burn anything in the ship. Remember you'll be inside the nova AoE when it goes off. It's being, literally, in the middle of a fusion explosion many orders of magnitude stronger than the most powerful nuclear weapon humanity has ever made.
Inverse r^2 shrinks pretty fast, to be fair.
Very likely, but not when you're IN the system when the sun goes nova. At that point everything in the system is destroyed. Especially since a nova and supernova will affect systems that are several lightyears away.
And I realized that digging deep bunkers in a planet or moon isn't likely to work either. The shockwave and succeeding waves of the explosion of the sun will shatter the planets (at the least strip away any atmosphere and cause massive earthquakes of 50 or higher on the Richter scale. The outer gas giants are likely to have their atmospheres stripped away and their moons blown out into space or shattered. I cannot see how anything can survive being in system when a sun goes boom. Or a ship(s) surviving it.
Eluvatar wrote:How is the radiation and heat supposed to go around the shielding pusher plate in space?
By being emitted from matter that has gone around the pusher plate. If the event is large enough to produce a usable impulse on a pusher plate, it will engulf the vehicle. It'd be like relying on waterproof boots to keep you dry as you cannonball into a swimming pool.
It's not quite a totally unsurvivable environment, it's a lot easier to wreck a planet than it is to wreck a buried bunker, but you'd want a lot of distance and a lot of shielding. Kuiper belt objects might suffice, Neptune and Uranus might be of use. If it's just a nova, Earth might be survivable, especially if it's shielded from the worst by the sun. There's a wide range of outcomes depending on what exactly happens..
Eluvatar wrote:How is the radiation and heat supposed to go around the shielding pusher plate in space?
By being emitted from matter that has gone around the pusher plate. If the event is large enough to produce a usable impulse on a pusher plate, it will engulf the vehicle. It'd be like relying on waterproof boots to keep you dry as you cannonball into a swimming pool.
That was my thought. The nova/supernova is simply too big for a ship to survive it while in the start system.
Mjolnir wrote:It's not quite a totally unsurvivable environment, it's a lot easier to wreck a planet than it is to wreck a buried bunker, but you'd want a lot of distance and a lot of shielding. Kuiper belt objects might suffice, Neptune and Uranus might be of use. If it's just a nova, Earth might be survivable, especially if it's shielded from the worst by the sun. There's a wide range of outcomes depending on what exactly happens..
How would Earth be shielded? It would be screwed even if it was just a nova. The atmosphere would be gone, the planetary crust shattered and magma coming out in countless places. The radiation burst would have fried, killed any lifeforms and the heat boiled away any water with the atmosphere. I cannot see how the outer planets could survive that well, the radiation and heat burst (which could last for days(?)) would put paid to anything possibly alive there. It would destroy any ship even in the outer system. The Kuiper belt would likely survive, but I am not sure how well any habitats would survive the radiation burst.
Eluvatar wrote:How is the radiation and heat supposed to go around the shielding pusher plate in space?
By being emitted from matter that has gone around the pusher plate. If the event is large enough to produce a usable impulse on a pusher plate, it will engulf the vehicle. It'd be like relying on waterproof boots to keep you dry as you cannonball into a swimming pool.
That was my thought. The nova/supernova is simply too big for a ship to survive it while in the start system.
Mjolnir wrote:It's not quite a totally unsurvivable environment, it's a lot easier to wreck a planet than it is to wreck a buried bunker, but you'd want a lot of distance and a lot of shielding. Kuiper belt objects might suffice, Neptune and Uranus might be of use. If it's just a nova, Earth might be survivable, especially if it's shielded from the worst by the sun. There's a wide range of outcomes depending on what exactly happens..
How would Earth be shielded? It would be screwed even if it was just a nova. The atmosphere would be gone, the planetary crust shattered and magma coming out in countless places. The radiation burst would have fried, killed any lifeforms and the heat boiled away any water with the atmosphere. I cannot see how the outer planets could survive that well, the radiation and heat burst (which could last for days(?)) would put paid to anything possibly alive there. It would destroy any ship even in the outer system. The Kuiper belt would likely survive, but I am not sure how well any habitats would survive the radiation burst.
Not sure about the Earth comment (I originally understood it as referring to the same sort of thing as the Neptune and Uranus bit), but I know what he was referring to with the outer planets: you can use them as shielding from the initial event by placing yourself in their shadow. Depending on the magnitude of the event, anything that happens afterwards might be survivable, as long as you don't have to deal with the full magnitude of the initial disaster.
Well, novae are likely not to be symmetrical, especially one that is externally triggered, so it could be better or worse depending on where the Earth is located with respect to the blast. If a type I supernova were to go off, symmetrically distributed, in an instant, then by my rough calculations, that would be enough energy to reduce the Earth to gravel. (approximately 8.9x10^32 Joules over the Earth's sun facing surface) I'll have to check the numbers for more distant bodies another time though, but I have a feeling that Neptune might be a nice place to hang out.
Now, if the event is longer than an instant, it might not involve vaporizing the entire planet. Supernovae are known to take more than a week to reach peak intensity, but I don't know enough about that process to do even a back of a napkin estimate.
Zakharra wrote:
How would Earth be shielded? It would be screwed even if it was just a nova. The atmosphere would be gone, the planetary crust shattered and magma coming out in countless places. The radiation burst would have fried, killed any lifeforms and the heat boiled away any water with the atmosphere. I cannot see how the outer planets could survive that well, the radiation and heat burst (which could last for days(?)) would put paid to anything possibly alive there. It would destroy any ship even in the outer system. The Kuiper belt would likely survive, but I am not sure how well any habitats would survive the radiation burst.
Not sure about the Earth comment (I originally understood it as referring to the same sort of thing as the Neptune and Uranus bit), but I know what he was referring to with the outer planets: you can use them as shielding from the initial event by placing yourself in their shadow. Depending on the magnitude of the event, anything that happens afterwards might be survivable, as long as you don't have to deal with the full magnitude of the initial disaster.
I was referring to the possibility of Earth being in the sun's shadow. The nova's going to be from hydrogen piling up on the neutron star from its collision with the sun. The sun would be massively disrupted, but better off being exposed to that than being in direct line of sight of what's going on with the neutron star immediately after the collision. (More of an x-ray burst than a nova, probably.)
So I had a moment to do the math, and if all (1.0x10^42) Joules of a type Ia nova were evenly distributed across the surface area of a sphere with Neptune's average distance from the Sun (2.548x10^20) kilometers, in an instant. That should only be (3.92x10^21) Joules per square kilometer. So not quite enough to instantly blow up the Earth at that distance, so probably not enough to blow up Neptune either. (although I don't have an estimate on how many Joules it would take to do that.)
icekatze wrote:So not quite enough to instantly blow up the Earth at that distance, so probably not enough to blow up Neptune either. (although I don't have an estimate on how many Joules it would take to do that.)
Check stardestroyer.net, I believe they ran those numbers for the Death Star.
What I could find was for a solid Earth and Jupiter.
The energy required to destroy the planet in question is 2.25 ⨉ 10^32 J. However, the destruction of large planets such as Jupiter can require much larger energy demands... we can estimate this energy to be 2 ⨉ 10^36 J.
Of course the Death Star delivers its energy at a single point that drills in and explodes outward, rather than on an entire surface that pushes in one direction. Not sure what kind of a difference that would make, but I think given the non-instantaneous nature of novae, their output is already low enough not to destroy a gas giant, so maybe it is a moot point.
