Re: Evacuate Earth
Posted: Mon Dec 07, 2015 2:56 pm
How is the radiation and heat supposed to go around the shielding pusher plate in space?
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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.Eluvatar wrote:How is the radiation and heat supposed to go around the shielding pusher plate in space?
That was my thought. The nova/supernova is simply too big for a ship to survive it while in the start system.Mjolnir wrote: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.Eluvatar wrote:How is the radiation and heat supposed to go around the shielding pusher plate in space?
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..
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.Zakharra wrote:That was my thought. The nova/supernova is simply too big for a ship to survive it while in the start system.Mjolnir wrote: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.Eluvatar wrote:How is the radiation and heat supposed to go around the shielding pusher plate in space?
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.
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.)Absalom wrote: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.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.
Check stardestroyer.net, I believe they ran those numbers for the Death Star.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.)
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.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.
Adjust the energy to compensate for the reduced mass, compare with averaged-out nova output, and you've got a decent first-guess. If you want to get fancy then consider the possibility of shearing off the surface, and figure out what would be required for the mass in question to be permanently lost instead of just turned into a very odd ring.icekatze wrote:hi hi
What I could find was for a solid Earth and Jupiter.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.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.
Mjolnir wrote: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.)Absalom wrote: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.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.
Then you're talking about a different scenario from the one I am, and an event that is probably not possible given the low mass of the sun.Zakharra wrote:Mjolnir wrote: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.)
If the sun goes boom,
Mjolnir wrote:Then you're talking about a different scenario from the one I am, and an event that is probably not possible given the low mass of the sun.Zakharra wrote:Mjolnir wrote: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.)
If the sun goes boom,
A neutron star hitting or making a close pass by the sun is most likely going to separate it from all the planets. The neutron star will have a mass at least around 1.4 times that of the sun. It's going to be the dominant gravitational body during the encounter. Assuming a pretty typical initial velocity for nearby stars, the sun will be on a hyperbolic trajectory resulting in almost a 90 degree change in direction with respect to the neutron star. The planets, passing at similar velocities but widely varying distances, will each be affected very differently.Zakharra wrote: Hhmm.. probably. But a neutron star hitting, or even passing close by the sun isn't going to do good things to the Earth. I cannot imagine there not being some sort of seismic events on the planet. Big ones. And this is assuming the orbits of the inner planets aren't shuffled/disarrayed.