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Napersky
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Sci Channel "Evacuate Earth" new
      #5583725 - 12/22/12 08:55 AM

Saw this last night and WOW. The scenario is a neutron star will reach earth in 75 years. The industrialized nations build an ark for 250,000 survivors to travel to Barnard's Star in 88 years.

The propulsion is Freeman Dyson's nuclear detonation from the Orion project.

Very sad though that earth couldn't get it's act together and everyone else had to die.


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David Knisely
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Re: Sci Channel "Evacuate Earth" new [Re: Napersky]
      #5584149 - 12/22/12 01:57 PM

It was kind of stupid. It sort of continues the NatGeo channel and other channels attempts to capitalize on people's fears (Doomsday Preppers, 2012 programs, etc.). For one thing, one need not go to another star to avoid a passing Neutron star that happened to gobble up the Earth. That stupid "generation ship" could have stayed near or in the solar system as an O'Neil colony, using both the sun's energy and the materials remaining in the solar system to build more O'Neil colonies if necessary, once the Neutron star had moved on out on its way through space. Also, the premise is ridiculous, as the chances of any star (let alone a rare neutron star) coming into the solar system and taking out the Earth in less than a century are incredibly small. The target destination of Barnard's Star was equally stupid, as that star is a red dwarf known to be a flare star (Tau Ceti, Epsilon Eridani, or even Alpha Centauri would have been better choices). They even forgot about using a Bussard ramjet drive system for their "interstellar" voyage, which would have gotten their speed into the relativistic range and thus allowed time dilation to be used. Sorry NatGeo, but once again, these fear mongering attempts earn them a fail. Clear skies to you.

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seryddwr
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Re: Sci Channel "Evacuate Earth" new [Re: David Knisely]
      #5584321 - 12/22/12 04:15 PM

The problem I've found with the ramjet is how to slow down. Once you turn the ship around, the ramjet intake is facing the wrong direction. It would be much more difficult to take in fuel that way... I suppose you could have retros, but it seems that it would be hard to redirect the by-products of a fusion reaction in that way.

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David Knisely
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Re: Sci Channel "Evacuate Earth" new [Re: seryddwr]
      #5585021 - 12/23/12 01:55 AM

Quote:

The problem I've found with the ramjet is how to slow down. Once you turn the ship around, the ramjet intake is facing the wrong direction. It would be much more difficult to take in fuel that way... I suppose you could have retros, but it seems that it would be hard to redirect the by-products of a fusion reaction in that way.




You would use a "ram-augmented" drive, using the Bussard collector to collect mass at some point in the flight to be used as reaction mass in a fusion powered reaction drive, which could be directed in reverse once you decided to begin your breaking maneuver. Another possibility would be to use a magnetic sail or "parachute" to do the breaking as you approached the target star. Clear skies to you.


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InterStellarGuy
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Re: Sci Channel "Evacuate Earth" new [Re: David Knisely]
      #5585030 - 12/23/12 02:10 AM

Quote:

It was kind of stupid. It sort of continues the NatGeo channel and other channels attempts to capitalize on people's fears (Doomsday Preppers, 2012 programs, etc.). For one thing, one need not go to another star to avoid a passing Neutron star that happened to gobble up the Earth. That stupid "generation ship" could have stayed near or in the solar system as an O'Neil colony, using both the sun's energy and the materials remaining in the solar system to build more O'Neil colonies if necessary, once the Neutron star had moved on out on its way through space. Also, the premise is ridiculous, as the chances of any star (let alone a rare neutron star) coming into the solar system and taking out the Earth in less than a century are incredibly small. The target destination of Barnard's Star was equally stupid, as that star is a red dwarf known to be a flare star (Tau Ceti, Epsilon Eridani, or even Alpha Centauri would have been better choices). They even forgot about using a Bussard ramjet drive system for their "interstellar" voyage, which would have gotten their speed into the relativistic range and thus allowed time dilation to be used. Sorry NatGeo, but once again, these fear mongering attempts earn them a fail. Clear skies to you.





They use Orion because it is technologically doable on what we have *now* and could build. There are still challenges to the Ramjet concept. For example, I think I read that the scoop would have to be as wide as 1/3rd of the distance from the Earth to the moon by current tech, also it is not known how to get the hydrogen to perform fusion once you get it.


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seryddwr
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Re: Sci Channel "Evacuate Earth" new [Re: David Knisely]
      #5585034 - 12/23/12 02:15 AM

Quote:

Quote:

The problem I've found with the ramjet is how to slow down. Once you turn the ship around, the ramjet intake is facing the wrong direction. It would be much more difficult to take in fuel that way... I suppose you could have retros, but it seems that it would be hard to redirect the by-products of a fusion reaction in that way.




You would use a "ram-augmented" drive, using the Bussard collector to collect mass at some point in the flight to be used as reaction mass in a fusion powered reaction drive, which could be directed in reverse once you decided to begin your breaking maneuver. Another possibility would be to use a magnetic sail or "parachute" to do the breaking as you approached the target star. Clear skies to you.



OK, that makes more sense. I was thinking of directly ramming the stuff into the reactor, using the kinetic energy of the stuff (as viewed from the ship's frame) to assist in heating and compacting it enough to achieve fusion.


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David Knisely
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Re: Sci Channel "Evacuate Earth" new [Re: InterStellarGuy]
      #5585050 - 12/23/12 02:38 AM

Quote:

Quote:

It was kind of stupid. It sort of continues the NatGeo channel and other channels attempts to capitalize on people's fears (Doomsday Preppers, 2012 programs, etc.). For one thing, one need not go to another star to avoid a passing Neutron star that happened to gobble up the Earth. That stupid "generation ship" could have stayed near or in the solar system as an O'Neil colony, using both the sun's energy and the materials remaining in the solar system to build more O'Neil colonies if necessary, once the Neutron star had moved on out on its way through space. Also, the premise is ridiculous, as the chances of any star (let alone a rare neutron star) coming into the solar system and taking out the Earth in less than a century are incredibly small. The target destination of Barnard's Star was equally stupid, as that star is a red dwarf known to be a flare star (Tau Ceti, Epsilon Eridani, or even Alpha Centauri would have been better choices). They even forgot about using a Bussard ramjet drive system for their "interstellar" voyage, which would have gotten their speed into the relativistic range and thus allowed time dilation to be used. Sorry NatGeo, but once again, these fear mongering attempts earn them a fail. Clear skies to you.





They use Orion because it is technologically doable on what we have *now* and could build. There are still challenges to the Ramjet concept. For example, I think I read that the scoop would have to be as wide as 1/3rd of the distance from the Earth to the moon by current tech, also it is not known how to get the hydrogen to perform fusion once you get it.




Nope, during their initial meeting "discussions" where they supposedly looked at all of the available possibilities, they mentioned a lot of possible methods for interstellar travel but did not include the use of magnetic or electrostatic ram-scoop drive systems like the Bussard. They even included anti-matter, which we can't make in great quantities and can't confine for very long. The Orion idea was OK as workable, but you would need a lot of bombs. Personally, I would have held out that some kind of fusion reaction drive system (either with fuel or ram-assisted) would have been more appropriate. We can do limited magnetic-confined fusion right now, so "opening one end" in the reaction to allow some of the plasma to act as the drive would be logical. The whole show seemed to have all the fancy sensationalist trappings that have been so irritating lately with all the 2012 doomsday stuff. NatGeo has been doing that for quite a while with the "When The Earth Stops Spinning", "When Aliens Attack", and other such nonsensical doomsday shows, so I guess I should have expected something like this. The only reason I caught this one was that I was home with the stomach flu. It is sad to see this, but I guess that National Geographic thinks they have to make their money this way. It just makes me wonder a little at the factual content of their other more "mainstream" shows. Clear skies to you.


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Napersky
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Re: Sci Channel "Evacuate Earth" [Re: David Knisely]
      #5585697 - 12/23/12 02:15 PM

NatGeo and remember this was on the Science Channel. They must be imitating "THE HISTORY CHANNEL" soon we'll see specials on "Aliens" and UFOS.

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