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Draconis
QUOTE (2bit @ Nov 6 2006, 04:17 PM)
and bringing the topic to SR products again, where can I get information on space related technology, property, and resources?  (Satellites, habitats, moon bases, terrestrial lift complexes...)  Is it all in Target: Wastelands?

Not an exhaustive list but a pretty good coverage.

SoTA: 2064 p.154 Module OMZ13
p.161 Yametetsu Mars mission lands

SoTA: 2063 p.119-121 and p.125 Shibanokuji Freefall resort

Wake of the Comet

Year of the Comet

Shadows of Asia
p.139 Svobodniy
p.31 Yang Lin Fat
p.133 Sonia Mikhalina
p.162 Pelawangan Space Port
p.205 Tyuratam Space Port
p.194 Narau Protectorate launch facilities

Target Wastelands (by far the best resource)
p.66-84 and p.124-129

Corporate Download
p.18-20 Zurich-Orbital
p.39 AresSpace

You're welcome.
Demerzel
You never started checking my math.

I never claimed a linear relationship between temperature and dm/dt. You made a bad assumtion, I never claimed such a thing.

Okay, my back of the envelope calculations were not the clearest and since you desire better clarity Iíll try to offer you a general formula.

Average Kinetic Energy based on temperature:
KE = (3/2) k T

Kinetic Energy of a nonrelativistic particle:
KE = (1/2) m v^2

Eliminate energy and solve for v you get:

v = sqrt(3 k T / m)

Thrust is the Force on the rocket. Newtonís second law:
F = M a (large M for the rocket mass, small m for ejecta mass)

Thrust = -v dm/dt

-v dm/dt = M a

dm/dt = M a / v

substitute in v and you get:

dm/dt = M * Sqrt (m / 3 k T) * a

So where you falsely assumed a linear relationship between dm/dt and temperature there is really an Inverse square root relationship!

Iím sorry Frank but youíre not even trying . . .

And Iím sorry but Solid Rocket Booster (SRB) Separation occurs at 2:07 in the shuttleís launch sequence. The Space Shuttle Main Engine then fires until 7:40, it throttles down and cuts out at 8:38.

So in fact my simple calculation is much closer to correct than you pretend, if youíd like a decent undergraduate level text on classical dynamics including a nice section on rocket science I recommend this book.
FrankTrollman
QUOTE
Iím sorry Frank but youíre not even trying . . .


Nope. I'm not. Because your basic assumption is inane. The impetus given from a man throwing a baseball off a wagon and a man dropping a baseball off a wagon are very different, and the temperatures are virtually identical.

It's not even a remotely plausible claim.

QUOTE
So where you falsely assumed a linear relationship between dm/dt and temperature there is really an Inverse square root relationship!


Fine. So the drop from 13 million kelvin to 3600 Kelvin only produces a 60 fold drop in forward motion and not a 1000 fold drop. This still doesn't really help because that still means that you're calling for the expungement of only .43% of the vehicle's mass every second.

And 510 seconds later you'd still have thrown out 89% of the vehicles mass.

But a shuttle only drops 75% of its mass on the up journey. Your math gives an upward cap of efficiency which is in fact lower than the actual yields of an extremely inefficient process: the external detonation of large amounts of fuel. There's all kinds of energy lost to lateral expansion and it's still substantially more efficient than you claim it possibly could be.

There is an underlying falsehood in your assumptions. I don't know where because I don't care enough. But I've got a nose. And when you start claiming that near zero kelvin rocketry can't work, I know we've been had.

Equal and Opposite Reactions move things through space. They really do. Which means that your math , even if it's correct, does not represent what you are claiming that it represents. And that's why I'm not checking it. The results do not square with the real world, therefore you are wrong.

-Frank
Demerzel
Iím sorry Frank, I gave you credit for a better understanding of Physics than I should have. As a result I didnít spell out some of the basics of how a simple rocket engine works.

Q: Why does the heat of the engine core have anything to do with the velocity of the propellant?

A: Unlike what you think when you envision an ďThe external detonation of large amounts of fuelĒ what Iím assuming is that youíve got some sort of bottle that is capable of containing a fusion reaction at a heat equivalent to that of the core of the sun. Particles in this fusion would be moving around with incredible velocities. Velocities that I have calculated for you already in the above. Then I allow you to port this plasma out into space in a linear jet that provides thrust based on a simple conservation of momentum. Thatís the thrust equation Iíve shown you. Don't forget that I'm giving for free that there's some way to continue to inject fusion fuel into this reactor core to maintain the reaction at a steady state.

What the space shuttle's solid rocket boosters do is they use combustion rather than fusion to create the heat that forces the propellant out the back of the rocket.

Commentary: You are unwilling to accept that what I showed you actually represents the space shuttle remarkably well. The primary difference being that the shuttle is launched using the combustion of H2 and O2, but ultimately itís a very hot core that allows a just of hot gas to be shot out the back at a velocity that is determined based on temperature. In fact the dm/dt that this very rough estimation yields is close to the actual space shuttle.

You canít accept that the space shuttle outputs 9800 kg/s at lift off because that much dm/dt could not be sustained for 510 seconds is a moot point because it is not sustained for 510 seconds. Solid rocket booster separation occurs at 2 minutes and 7 seconds in the flight. In fact I mentioned that above, but youíre stuck on that 510 seconds for some reason.

After the 2:07 SRB separation the Space Shuttle Main engine continues to burn, at a much slower rate, and I havenít attempted to represent that in any way here. And by claiming a 510 second burn to orbit youíre misrepresenting the essential two stage nature of the Space Shuttle and itís Launch mechanism.

My question for you:
But I take it you donít want to accept that this is the type of engine you would have to use. Is it that you instead want to take the fusion reaction and generate electricity with it in order to use a type of particle accelerator and boost your reaction mass to a significant fraction of the speed of light?

Am I correct that that is what you are proposing?
Moon-Hawk
QUOTE (Demerzel)
But I take it you donít want to accept that this is the type of engine you would have to use. Is it that you instead want to take the fusion reaction and generate electricity with it in order to use a type of particle accelerator and boost your reaction mass to a significant fraction of the speed of light?

That's the basic principle of an ion thruster, right? You accelerate charged particles to near-relativistic velocities, so you can get away with a very low reaction mass, and get very high efficiency. The only downside, as I understand it, is that with modern power sources it's difficult to generate a lot of acceleration. A fusion reactor would solve that, I would imagine.
But I'm not a rocket scientist, so I'm not claiming anything.
FrankTrollman
Demerzel, at its core you are proposing that the temperature of the outgas is the singular source of velocity for it. This is not true in any reference frame. Temperature motion of particles goes in every direction, and in aggregate generally sums to zero.

The temperature of the stream is, therefore largely waste energy. So the supposition "If 100% of the forward motion comes from waste energy..." is flawed to begin with. Waste energy isn't giving you any forward motion, that's why it's waste!

You talk about this as if it was somehow a Maxwell's Daemon Drive (which would be awesome). It's not. It's a fusion engine that produces a very large amount of power and squirts it out the back in the form of plasma that is accelerated to high speed (probably with magnets).

The acceleration is modelable in an entirely Newtonian fashion. Energy out the back equals forward acceleration. We need on the order of 10^16 Joules, but we get on the order of 10^14 Joules for every Kilogram of fuel so I'm not worried. With only a 10% efficiency we could get there with a tonne of fuel. We're probably going to want more like 20 tonnes of fuel because getting even a 10% efficiency out of high energy reactions is laughable.

The standard rocket propellent is sent out the back via expansion, which doesn't require heat to be produced. If you'll recall, liquid oxygen tanks can become quite hazardous projectiles when breached, and become extremely cold when doing so. The compressed gas decompresses explosively - and consumes heat in the process of phase shifting from liquid to gas.

Your fundamental assumption is without merit. Your very first sentence kills the entire argument. By comparing the motion energy of the temperature of individual particles to... really anything, you're not modelling rocketry at all.

-Frank
knasser
QUOTE (FrankTrollman @ Nov 6 2006, 12:28 PM)
 
I'm going to stop checking your math because it's obviously wrong.


It actually looks right to me. I'm not saying I can't be proved wrong, but I think if you're saying his maths isn't right, the onus is on you to point out where. It seems accurate to me.

As I understand the way a plasma engine would work however, it doesn't work on high temperature forcing the ejecta out, but on the fact that the particles in a plasma are highly charged and are accellerated out using a powerful elextromagnetic field. This means that it works in quite a substantially different way to the rockets that you both are talking about.

Now this field can be powered by the same reaction that is producing the plasma, but it's not free energy. You have to take this into account as well. That's more complicated and perhaps not necessary to work out for this argument which is why I stuck to basic physics in calculating the energy costs of accelerating and decellerating a given mass at the beginning of this thread. But I am pretty sure that a plasma drive is more of a high-efficiency, low power drive suitable to sustained travelling rather than the less efficient, but super-punching conventional rocket power. That may be why Demerzal has rightly interpreted Frank to be talking about "temperature" based propulsion, i.e. conventional rocketry.
Demerzel
QUOTE (Moon-Hawk)
A fusion reactor would solve that, I would imagine.

The unfortunate thing is that it wouldn't really, while fusion is a great way to generate a ton of energy it's energy in the form of heat. If you want to do anything with that energy, other than vent it out the back as in the plasma rocket I've been trying to describe, you've got to convert it into another form of energy. Now you start having to talk about efficiency losses in heat engines.

Converting to electricity to create a immense particle accelerator would require a way to turn that heat into energy. The problem is a heat engine requires not just a heat source but a heat differential. And while space is cold, it's also a vacuum so it's also a great insulator, all you get is radiative heat loss there is no conduction to the vacuum and no convection currents to carry away waste heat. You could allow water to boil away into the vacuum of space and carry away a lot of heat, but there you go wasting a ton of mass again...
hyzmarca
A quick fact check shows that fuel is, in fact, 92% of the launch system's mass (give or take; I compared gross weights to empty weights so the estimate could be slightly high).
After the SRBs are jettisoned the shuttle and the external fuel tank actually weigh so much that the thrust from the Shuttle Main Engines provides less force than gravity and the shuttle begins to slow down until it has burned through a certain amount of fuel. By the last 10 seconds it has depleted more than 75% of its mass in fuel and actually has to throttle down to keep the acceleration under 3gs.

Math that shows the shuttle losing more than 75% of its mass while leaving the atmosphere can't be rejected on that fact alone because the shuttle does lose more than 75% of its mass while leaving the atmosphere
knasser
QUOTE (FrankTrollman @ Nov 6 2006, 04:58 PM)

The acceleration is modelable in an entirely Newtonian fashion. Energy out the back equals forward acceleration. We need on the order of 10^16 Joules, but we get on the order of 10^14 Joules for every Kilogram of fuel so I'm not worried. With only a 10% efficiency we could get there with a tonne of fuel. We're probably going to want more like 20 tonnes of fuel because getting even a 10% efficiency out of high energy reactions is laughable.


Just a word on these efficiency figures that are starting to be repeated. I can't comment on them as far as conversion of heat energy to electricity goes, but if you're talking about accelerating a plasma out of the ship using electromagnetic force, which I think you've confirmed that you are, then only about 20% of the plasma can provide thrust because the other 80% resulting from Deuterium-Tritium is neutrons which have no charge and can't be accelerated. You're back to depending on Demerzel's heat-energy equations for that. So the efficiency might be a bit less than you would hope.
FrankTrollman
QUOTE
A quick fact check shows that fuel is, in fact, 92% of the launch system's mass (give or take).


Granted.

But the launch mass is 2.04 million kilograms, and it burns off only 1.59 million kilograms during the 510 second jump into orbit. There is additional fuel onboard, but that's because those selfish astronauts want to get back. wink.gif

QUOTE
I can't comment on them as far as conversion of heat energy to electricity goes, but if you're talking about accelerating a plasma out of the ship using electromagnetic force, which I think you've confirmed that you are, then only about 20% of the plasma can provide thrust because the other 80% resulting from Deuterium-Tritium is neutrons which have no charge and can't be accelerated. You're back to depending on Demerzel's heat-energy equations for that. So the efficiency might be a bit less than you would hope.


Unless we're doing He3 + D reactions, in which case all products would carry a positive charge.

But regardless, Demerzel's Heat equations depend upon something which is not true: the concept that all motion comes from the temperature derived motion of the particles themselves. That's not true. It's not even a little bit true.

1 Kilogram of fuel gets 10^14 Joules. I don;t know what form all that energy takes, because for health and safety reasons I don;t have a fusion engine in my yard. But I don''t actually care. If you can focus even 10% more of the resulting energy to go in a direction of your choice than radially throught the universe (and you'd better, you're standing right next to this thing) - you can get there on a tonne of fuel.

That's much less than Demerzel is reporting. Maybe he's under guessing the temperature? Maybe he isn;t calculating the forward velocity obtainable by magnetically reflecting the newly liberated protons? I don't know. I don't even care, because I'm not actually building one of these things.

What I do know is that the actual energy being produced by the actual reaction is many orders of magnitude larger than the total amount of energy needed to get there and back in the allotted time frame, so I'm done. I honestly don't even care what hang-up is causing Demerzal to come up with the wrong answer.

But conservation of mass and energy proves beyond doubt that his answer is incorrect. And that's good enough for me.

-Frank
Demerzel
I think this argument may have stemmed from the basic premise that I tried to give a simple example of how 1g acceleration for 4 days (2 days out 2 days back) is untenable. Unfortunately it degenerated to a defense of a short and oversimplified counter example.

A good source of info on propulsion is this article on wiki...

I continue to contest that it'll be highly unlikely that you could get 1g of accelleration for something on the order of days... If you want to switch the argument to ion engines we can, but you've got enormous efficiency issues, plus you're talking about scaling a technology to broken proportions.
FrankTrollman
From that site you linked:

QUOTE
Observe that the more fuel-efficient engines can use far less fuel; its mass is almost negligible (relative to the mass of the payload and the engine itself) for some of the engines. However, note also that these require a large total amount of energy. For earth launch engines require a thrust to weight ratio of much more than unity. To do this they would have to be supplied with Gigawatts of power ó equivalent to a major metropolitan generating station. This would need to be carried on the vehicle, which is clearly impractical.


But with Shadowrun tech, there is a contained fusion drive. Carrying the major metropolitan power generator on board isn't clear impractical in Shadowrun's 2071.

That's the deal. The energy involved is very large, but in Shadowrun that's a solved problem.

-Frank
knasser
edit: Deleted post - the argument is dead. Just objected to Demerzel's posts that seem correct to me being dismissed as "hangups."
Demerzel
QUOTE (Frank)
1 Kilogram of fuel gets 10^14 Joules.


Where do you get this number?

QUOTE
I don;t know what form all that energy takes


I do, it makes heat. What is heat? Well thatís actually a pretty deep physics question and one I canít really answer without putting you through an actual thermodynamics class. The simplest answer and the on youíll probably have to accept is that it relates to the kinetic energy of the constituent particles.

QUOTE
If you can focus even 10% more of the resulting energy to go in a direction of your choice


I think this statement alone best exemplifies your basic misunderstanding of the physics involved.

Energy is a scalar; you cannot direct it any way at all.
Demerzel
Okay Frank, lets use the example there of a Ion Drive. Itís got an efficiency of 25kW per N of thrust.

So if I have a 100,000 kg (Space Shuttle sized) craft.
1g nearly 10m/s^2 would require 1,000,000 N of force.
25kW/N means 25,000,000 kW, or 25GW OUTPUT from a power generator.

Now if I give you a better than possible efficiency of 50% that means that 25GW of power output is waste heat. Where do you propose that goes? In SR the generators youíre talking about put it in a river or into the ocean. Where is your enormous heat sink?
FrankTrollman
QUOTE
Where is your enormous heat sink?


A glowing contrail of plasma?


QUOTE (Artemis Project)
The deuterium and helium-3 atoms come together to give off a proton and helium-4. The products weigh less than the initial components; the missing mass is converted to energy. 1 kg of helium-3 burned with 0.67 kg of deuterium gives us about 19 megawatt-years of energy output.


I'm seriously not concerned. That's 6.9 x 10^6 kW days out of 5/3 of a kilogram. If you need only 25 kW per Newton, you're going to be able to - theoretically - keep our craft going the whole time on 12 kilograms of fuel.

Obviously you're never going to get that kind of efficiency. But if the absolute maximum is 12 kilograms, you'll understand why I'm willing to handwave the possibility with dozens of tonnes to work with.

-Frank
hyzmarca
QUOTE (FrankTrollman @ Nov 6 2006, 05:15 PM)
QUOTE
A quick fact check shows that fuel is, in fact, 92% of the launch system's mass (give or take).


Granted.

But the launch mass is 2.04 million kilograms, and it burns off only 1.59 million kilograms during the 510 second jump into orbit. There is additional fuel onboard, but that's because those selfish astronauts want to get back. wink.gif

You seem the be forgetting to factor in the mass of the jettisoned fuel tank and SRBs. The maximum amount of fuel the shuttle can retain is 40,414.4kg (gross weight of orbiter-empty weight of orbiter), and that is being generous. It will be less depending on the shuttle's cargo.
The orbiter itself is only 109,000 kg when full.

It takes a lot more fuel to reach orbit than it does to land. When landing, gravity does most of the work. That's the great thing about conservation of energy and the relationship between height and potential energy.
TheRedRightHand
Wow, who says roleplayers are a bunch of nerds...? smile.gif
knasser
QUOTE (FrankTrollman)
QUOTE
Where is your enormous heat sink?


A glowing contrail of plasma?


Well you gave yourself a 20% efficiency earlier. So with enough energy to run New York for an afternoon, you've still got 80% of it you're trying to radiate off from your spaceship somehow. Going to get hot in there.
Demerzel
The glowing contrail of plasma would be the output energy from the reaction the waste energy would have to go into some sort of heat reservoir. Basically it would heat your ship. The waste heat is just that waste and you have to do something with it, it is all the energy that you cannot convert to useful work due to the fact that no power generator is 100% efficient.

So basically if I give you a 50% efficient engine, and you need 25GW of power to keep it accelerating at 1g, then youíve got 25GW of waste heat to deal with.

Water absorbs a huge amount of heat per unit mass compared to the things your ship is likely made of like metal.

If your ship absorbs heat just as well as water, at 25 Celsius, 25 GW of waste energy would heat your ship 62.5 Kelvin per second. How long will your crew survive?

Okay I know what youíre saying that heat will go somewhere, itís not confined to the ship. But there is no conduction of heat from the ship into space (a vacuum), only radiative heat loss will occur. In order for the radiative heat loss to emit 25GW of energy it would have to be glowing hot.

So you want some sort of huge radiators that will reduce that heat, then youíve got to add that weight, and increase your power output and in the end youíre going to be talking about an immense amount of heat sink. Also the hotter your heat sink the worse your efficiency.

Basically, your 2 day there and 2 day back at 1g trip is just ridiculous. Take two months to get there and two to get back and there you go, but why are you in this ridiculous hurry?
hyzmarca
Well, if you want to get into pure speculative theoretical limits then 2kg of carbon could hold 5.594MJ of heat before melting and if flattened into a 100 square meter sheet could emit (eT)22.041GW at this temperature, where (eT) is the emissivity correction factor of the carbon at this temperature.

The actual mass and specific heat of the radiator doesn't factor into the equation except as they effect temperature. Since a high-temperature radiator is good a low-mass and low specific-heat radiator actually benefits you in some ways.
Demerzel
Carbon is a poor conductor however so as a heat sink it would be unreliable...
knasser
SR2070 technology - how about this: You create a nano-material with strictly controlled bonding forces between the molecules. At specific temperature threshold, they "evaporate" away from the ship. You're in Space so you don't care about the super fine cloud of particles that your ship leaves behind it like an all-consuming fart. It's inherantly degrading, but it's a neat way to get rid of heat and you can make it eight-foot thick if you want. I'm sure SR2070 technology can also come up with a neat little capilliary system to get the heat out to the heat sink "shell".

If we're talking science-fiction (and we are), you could even vary the strength of the bonds in the material as needed with varying current.

My idea is so brilliant that I should patent it, but instead I shall donate it to the public domain, for the greater glory of Dumpshock. biggrin.gif
hyzmarca
QUOTE (knasser @ Nov 6 2006, 07:31 PM)
SR2070 technology - how about this: You create a nano-material with strictly controlled bonding forces between the molecules. At specific temperature threshold, they "evaporate" away from the ship. You're in Space so you don't care about the super fine cloud of particles that your ship leaves behind it like an all-consuming fart. It's inherantly degrading, but it's a neat way to get rid of heat and you can make it eight-foot thick if you want. I'm sure SR2070 technology can also come up with a neat little capilliary system to get the heat out to the heat sink "shell".

If we're talking science-fiction (and we are), you could even vary the strength of the bonds in the material as needed with varying current.

My idea is so brilliant that I should patent it, but instead I shall donate it to the public domain, for the greater glory of Dumpshock. biggrin.gif

Except when you fly back through the particles on your return trip and they punch holes in your oxygen tanks like the superheated birdshot that they are.

Far better to use a lattice of carbon nanotubes as a giant radiator sail as it is possible to create nanotubes with conductive properties. You're still screwed if you run into a cloud micrometeorites, of course. They'll probably swiss-cheese the radiator.

The important thing is to have a high melting point, good conductivity, and enough strength to stay together when flattened into an extremely large and thin sheet and put under the stress of acceleration.
knasser
QUOTE (hyzmarca @ Nov 6 2006, 07:38 PM)
QUOTE (knasser @ Nov 6 2006, 07:31 PM)
SR2070 technology - how about this: You create a nano-material with strictly controlled bonding forces between the molecules. At specific temperature threshold, they "evaporate" away from the ship. You're in Space so you don't care about the super fine cloud of particles that your ship leaves behind it like an all-consuming fart. It's inherantly degrading, but it's a neat way to get rid of heat and you can make it eight-foot thick if you want. I'm sure SR2070 technology can also come up with a neat little capilliary system to get the heat out to the heat sink "shell".

If we're talking science-fiction (and we are), you could even vary the strength of the bonds in the material as needed with varying current.

My idea is so brilliant that I should patent it, but instead I shall donate it to the public domain, for the greater glory of Dumpshock. biggrin.gif

Except when you fly back through the particles on your return trip and they punch holes in your oxygen tanks like the superheated birdshot that they are.

Far better to use a lattice of carbon nanotubes as a giant radiator sail as it is possible to create nanotubes with conductive properties. You're still screwed if you run into a cloud micrometeorites, of course. They'll probably swiss-cheese the radiator.


Ready for you. smile.gif

The route you fly back wont be the route you flew there. Where you're coming from and where you're going to are in motion.

Also, could use a Laser Broom!

EDIT: I like the lattice of carbon nanotubes, though. Once they start to glow orange from the heat, your ship will look beautiful. Like a giant firey train of lace. Ahhhhhh!
Draconis
C'mon argue more physics. I want to see digital blood.
If physics classes where this amusing I might have stayed awake through them.
FrankTrollman
Uh... sure.

Plasma expansion is a refrigerant. The phase shift and volume expansion absorb energy and reduce temperature.

Discuss. wink.gif

-Frank
Demerzel
I'd like to think the Physics classes I tought while working on my Masters were this fun. I don't think I'd get a majority of votes from my students however.
FrankTrollman
Oh, and a significant portion of energy popping out of fusion reactions does so in the form of neutrinos, which are close to non-interactive with normal matter. That means that a very large proportion of energy loss comes in a form that does not neat to be thermally dissapated - it's simply a form of radiation which passes harmlessly through your ship in equal measures in all directions.

So the heat sink problem isn't as bad as you might think for looking at the numbr of joules and the efficiency of the propulsion.

-Frank
Demerzel
Well first off, your statement regarding the expanding plasma would work as a refrigerant is true, however what it would be cooling is the core of your reactor and that cooling would have to be compensated by some energy releasing reaction (such as fusion) or else your core would peter out before very longÖ

Then as to your heat exiting as neutrino statement. Well, energy is lost from the fusion reaction in the form of neutrinos. However the efficiency numbers I used to give you a simple feasibility for your rocket were based purely on the electricity production. Basically if youíre unwilling to use a simple rocket and insist on some sort of ion drive you have to convert the heat energy generated by your energy source (fusion/fission/combustion of methane byproducts from consumption of beans) into electrical energy to create the voltage differential you want to use to accelerate your reaction mass.

Without even talking about the efficiency of your fusion process, just the heat engine necessary to run your power generator has an efficiency limit. The Carnot efficiency is the maximum possible based on thermodynamic principals. Basically if I give you for free a 50% efficient generation process Iím being extremely generous. So without even considering the unusable heat generated in your fusion core (for example those nasty neutrons that cannot be contained in your magnetic bottle because they are neutral and turn your stable isotopes in your ships hull (or your body) into radioactive sources.

Frankly I basically spotted you a fusion rocket with a core as hot as the sun and you said I was being unreasonable. Where in fact if you had that weíd be regularly flying to Saturn to bring back Ice from the rings to use as reaction mass because that would be freakishly amazingly efficient as long as you donít want to do it all in one dayÖ

The key resource that will allow space travel in our solar system is patience.
Draconis
Ah there we go.....
Garrowolf
okay so the physics lesson was interesting but I thought I might point out something.

If the whole point of going fast was having to do with the comfort of the crew then I can think of a better solution entirely within Shadowrun tech. Just put everyone in a small centrifuge in the center of the ship in long term sleep. Then connect them to the main computer in hot sim. Make sure you have several small independant power sources so they are not in danger easily.

The actual ship may be a large rocket but for the crew it could be the enterprise d. Just give them lots of drones that they can control in VR and they can fix things. Then rotate the crew stifts with the frame rate of on duty personel varying with need of reaction so during the dull portions of the trip you experience time at a fast pace and when you are in danger it goes to normal time. You might only need a few days worth of experience to cover the entire several month trip.

That way there is no negative mental impact and you don't have to waste energy.
hyzmarca
If they're in artificial hibernation under artificial gravity for 6 months then they're all going to die from infected bed sores before they reach Mars. If they're in artificial hibernation without artificial gravity for 6 months then they're likely to die of heart failure the second they try to move.

The problem isn't the comfort of the crew. The problem is the massive health problems associated with low gravity environments. The heart doesn't have to work against gravity so it weakens dramatically, for example. Bones become brittle. Muscles lose mass and tone. Really, a low gravity environment is very dangerous to human health and so is 6 months of artificial hibernation.
Garrowolf
so you either have some sort of acceleration gel or you have some drones change the sheets. Maybe the bed vibrates to massage their butts.

Hyzmarca, it seems like you are just arguing against the possibility instead of offering alternate ideas. Do you just not like the idea of space travel or do you think it should only occur at a certain tech level where all the problems are solved?
FrankTrollman
Shadowrun technology provides the ability to keeppeople alive in gravity free hibernation for years - like Roxborough. Unfortunately, it is like Roxborough: your body no longer functions if you ever take it out of the zero gravity holding pattern.

I have no idea how Zero-G life extension is supposed to work, but it does exist in canon Shadowrun. It isn't part of the plan if you intend for the crew to ever accomplish anything at the end of their journey, however.

---

In general, Shadowrun movement is split harshly into the Haves and the Have-nots. On Earth, there are those able to use Movement on their vehicles and transport goods faster using less fuel and in less danger than anyone else. And then there's the people who can't and they have to deal with the fact that the oil has run out and they are stuck with methane vehicles running slow routes.

In space there are people who can afford to make and operate a fusion engine, which costs a crap tonne of nuyen.gif and runs off of fuel found on the Lunar surface by Ares' mining station - and there's everybody else who has to come up with ridiculously contrived methods to keep their people alive in space at low gravity for long journeys.

That's how Shadowrun movement works. There is an incredibly limited amount of frieght that is so fast that it might as well be teleported; and then everything else is stuck moving at the slow ponderous speed of a cammel caravan. Literarily this allows players to either skip from one location to the next with what amounts to a cut and a bit of locative subtitles or make a slow and dangerous journey from one land to another overcoming challenges the whole way. Both stories can exist in the Shadowrun world because fast transport exists and yet it is limited in availability.

Not everything in space moves at the fast speed. Only the big things. The expensive things. The things that absolutely, positively, have to make it to Mars by Saturday morning.

-Frank
hyzmarca
QUOTE (Garrowolf)
so you either have some sort of acceleration gel or you have some drones change the sheets. Maybe the bed vibrates to massage their butts.

Hyzmarca, it seems like you are just arguing against the possibility instead of offering alternate ideas. Do you just not like the idea of space travel or do you think it should only occur at a certain tech level where all the problems are solved?

I'm not arguing anything. I am simply putting out facts.

Hibernation is a bad idea. Period. Aside from the health risks, somebody has to be awake in case HAL decides to space everyone.
Usually, all of the astronauts will perform vital functions onboard the craft.

However, it isn't a bad idea to have a few video games around to provide them with something to do.

On the issue of gravity, it is technically trivial to simulate gravity with today's technology. Only budgetary issues keep them from actually doing it. So, a simulated 1g enviroment is not too much to ask for.


As for dealing with astronaut boredom on long trips, I recommend a gender mixed crew with lose morals and contraceptive implants; either that or just have an all-gay crew.
The Jopp
Ok, Iím no-brainer when it comes to these subjects but when it comes to crew survival there are several options in SR 2070.

The Crew Ė Medical Solution
Submerge crew in shock-absorbing gel while wearing life sustaining suits (Iím talking a kind of wetsuit here, not a primitive 2006 space suit). Add some basic cyberware for drone control as mentioned earlier.

The suits will include smart materials and myomer muscle bundles that massage the astronauts muscles so that their bodies muscle mass does not degenerate. Then we add Bone Augmentation to strengthen the bones for the long journey and possible some plastic bonelacing as support.

An expert Autodoc system (or even better Ė a medically trained astronaut that takes care of the crews health AND and Autodoc that can dispense nanites and drugs that can monitor their health.

The Crew Ė Alternative Cyber Solution
If we go fully extreme we add fully cyborged astronauts with complete limb replacements so that they mostly need spares. This way they can also skip survival suits with massage Ė An artificial hearth might be good as well since the hearth muscle might be affected by low gravity for an extended time.

The Ship
As I said, Iím no Physics major (or minor for that matter so Iíll just wing it here.

What technology exists in SR4? Particle Accelerator? Fusion Plants? Ritual magic? New materials.

1. The ship has as little metal components as possible and is made of new light smart materials significantly reducing weight (new material for us but have existed for 10-20 years in SR4.)

2. Ritual Magic. Ritual Magic boosts the ship up into the upper atmosphere where it ignites booster rockets (this also reduces weight.)

3. Improvements in engine design have improved fuel economy of booster rockets.

4. The entire crew is rigger trained to handle drones as most EVA will be done by them.

5. No actual landing will take place on mars by humans, a lander with several different drones will be sent down and/or flown over the area.

6. Solar powered High Altitude drones will simply drift over the planet and send data back to earth.

7. Every available sensor technology will be searching the planet for life.


IF a landing is to take place by human crew the cost will increase significantly and the only reason for actually taking such a cost is to se if an awakened individual can sense anything of the planets biosphere.

IF an awakened individual is going on the trip then there is extra costs in case of expert training to NOT use magical abilities in space (think about it, itís like Unlearning how to breathe Ė for a mage it is a natural thing to use magic Ė like walking.)

IF an awakened individual is going it might be required to have a small biosphere onboard (a small area filled with plants perhaps).

IF sending down a mage then they might manage with a small one-man shuttle Ė thus conserving fuel and space.

Another solution might be to send down awakened animals and monitor them.
Garrowolf
why not a probe with that biolum stuff that glows around magic. Then send them all around on drones. Just have enough to get readings of yes/no without the risk to a mage.
The Jopp
QUOTE (Garrowolf)
why not a probe with that biolum stuff that glows around magic. Then send them all around on drones. Just have enough to get readings of yes/no without the risk to a mage.

Oh, I've completely missed that stuff. Excellent Idea. Then all they need is a small crew that can monitor and control the drones. I would assume that the signal rating on those drones would be around 10+ and include good ECCM to filter out disturbances.

No need for a mage then.
hyzmarca
There is no need for Rube Goldberg sleep chambers when simulated gravity works just fine.

I still say with blood-god exploit is the best fastest and safest way to go about space travel in SR.


For coolness, people should land on Mars and they should be heavily armed just in case the aliens are hostile. Unmanned probes suck.
FrankTrollman
In 2064, there had already been at least three landings on Mars, with various levels of secrecy and various numbers of humans onboard since the Awakening. Project Discovery (NASA), Project Cydonis (Ares), and Project Tereshkova (Yamatetsu).

In 2070, Evo has a permanent base on Mars.

In 2071, getting to Mars has never been easier.

-Frank
Demerzel
Easier than ever it may very well be, but a weekend trip it is not.

A 6-month trip is also long compared to what Iíd expect out of SR4 level technology. A low-energy transfer orbit will take something like 18 months. The Mars Direct Plan calls for a high-energy transfer orbit that will take 6 months. If you maintain constant acceleration with a reasonable value (more like .01 to .04 g rather than 1g) you can shorten that significantly.

Iím not prepared to take the time necessary to calculate this kind of thing, itís not a time commitment Iím willing to take on for a DSF argument, besides itís not like Frank would believe my calculations anyhow. But be a little conservative in your estimate and say it would take 1 to 2 months, the health problems arenít nearly as huge and likely can be mitigated with SR level medicine, and youíre not abusing science like a red headed stepchild.

Plan ahead and you can send important things like landing craft and extra reaction mass ahead of the trip on a low energy orbit. But letís consider the past 50 years of advancement in space technology and project that ahead, with a fracturing of nations worldwide global strife and all the problems associated with that . . .

FrankTrollman
If you are going nuclear at all, and you can do it at .1 G, you can do it at 1 G.

The problem with increasing acceleration is that 10 times the acceleration requires 10 times the energy per kilogram for your journey. That means that you need 10 times the fuel. For a chemical propellant, that's a big deal, because the fuel is the vast majority of the mass. So you need 10 times as much fuel per kilogram and have almost 8 times as much mass and that needs 10 times as much fuel and so on and so forth - ithere's non-fuel mass in there so it doesn't go to infinity, but the total fuel requirements are impractically large.

But Nuclear drives don't work that way. The vast majority of the mass is the reactor itself. The fusionable materials are measured in kilograms, not tonnes. Putting in ten times as much fuel just means you can't take quite as many ham and turkey sandwichs, it doesn't mean that your vehicle is some whole number more massive overall.

That's the breakpoint. Once fuel to get energy out of isn't the primary source of mass, acceleration is pretty much arbitrary all the way up to the point where you'd kill the crew.

Nuclear engines propel the USS Nimitz through water on less than two kilograms of fuel per day, and that's fission. It's 100 tonnes and was built in 1975, I'm sure that in 100 years there has been some progress in this field.

The basic rocketry nightmare - that faster acceleration needs more fuel which means more mass which means more fuel which means more mass.... does not apply to a nuclear engine in any meaningful way. The engine is massive, expensive, and technically difficult. The fuel is expensive, rare, and dangerous - but the fuel isn't massive. It's man-portable if it for some reason came to that.

If you can keep a submarine moving around under water for five years, you can keep a spacecraft going at 9.8 m/s^2 for five days.

-Frank
kzt
QUOTE (FrankTrollman)
Nuclear engines propel the USS Nimitz through water on less than two kilograms of fuel per day, and that's fission. It's 100 tonnes and was built in 1975, I'm sure that in 100 years there has been some progress in this field.


Um, exactly how does a propeller turning = superhot plasma streaming out the back at a significant fraction of light speed? And the great thing about being surrounded by water is that it makes it easy to get rid of the heat. It's just a wee bit harder when surrounded by hard vacuum.
Demerzel
Wow, I canít believe you still believe that after all thisÖ

QUOTE (FrankTrollman)
Nuclear engines propel the USS Nimitz through water on less than two kilograms of fuel per day, and that's fission. It's 100 tonnes and was built in 1975, I'm sure that in 100 years there has been some progress in this field.


The USS Nimitz has the entire ocean worth of reaction mass floating around under it. If you spin a propeller out in space do you think you will generate thrust? Hell, letís just give the astronauts oars and make them row to Mars.

QUOTE (FrankTrollman)
The basic rocketry nightmare - that faster acceleration needs more fuel which means more mass which means more fuel which means more mass.... does not apply to a nuclear engine in any meaningful way. The engine is massive, expensive, and technically difficult. The fuel is expensive, rare, and dangerous - but the fuel isn't massive. It's man-portable if it for some reason came to that.


Nothing changes with a nuclear energy source. Ultimately you have to convert that energy into momentum.

QUOTE (FrankTrollman)
If you can keep a submarine moving around under water for five years, you can keep a spacecraft going at 9.8 m/s^2 for five days.


Again, just like the Nimitz the entire ocean provides an enormous source of reaction mass. Also an airplane uses the air around it for reaction mass, even with a propeller engine. The propeller or jet accelerates the gas from the air, the propeller uses mechanical energy to accelerate it a jet uses a combination of heat energy and mechanical energy a rocket uses purely heat, forces the air backward and creates thrust.

There is no immense source of reaction mass for you to push against in space, thatís why it has to be rocketry in one form or another. Even an Ion drive uses the mass of ions accelerated and shot out the back, and even that is subject to the basic law of conservation of momentum, regardless if youíre talking about relativistic or non-relativistic momentum. And that means Thrust = -v dm/dtÖ
Butterblume
QUOTE (Demerzel)
Nothing changes with a nuclear energy source.  Ultimately you have to convert that energy into momentum.

Stream out the plasma through a magnetic nozzle to achieve thrust.

BTW: there are a few zeros missing in the weight of the nimitz, or maybe a k before the t (100 kt seem much more reasonable).
Demerzel
QUOTE (Butterblume)
Stream out the plasma through a magnetic nozzle to achieve thrust.

Sure, we've talked about plasma rockets, but Frank wont accept the limitations that implies and demands a more efficient drive...
knasser
QUOTE (Demerzel @ Nov 9 2006, 02:32 PM)
QUOTE (Butterblume @ Nov 9 2006, 11:21 AM)
Stream out the plasma through a magnetic nozzle to achieve thrust.

Sure, we've talked about plasma rockets, but Frank wont accept the limitations that implies and demands a more efficient drive...


Which means using electromagnetic force to drive the plasma out of the back of the ship. And to power that, you're converting the heat into energy again. I've learnt quite a bit in this thread. From other sources, it seems that plasma engines are generally considered to be an efficient, but low impulse mode of propulsion. The exact opposite of accellerating at 1g for two days, really.
FrankTrollman
Yes, those are kilotonnes, not tonnes. Sorry, it was supposed to be ktonnes. Sigh.

Anyway, Nuclear Fusion is a state function. The path to completion is irrelevent and the energy output is the same regardless. Maybe the entire reaction is kept in magnetic containment and ejected whole out the back? Maybe the emmitted photns are collected by a pigment and then released as lasers out the back? I don't know.

I don't even care, because fusion power is not possible with the technology of 2006 and it is possible with the technology of the 2070 awakened world. The energy put out by the reaction is predictable and known based on the stability of the isotopes at the beginning and the end. And that energy is many thousands of times greater than what is needed to propel thee craft across the divide of space.

1G isn't a big deal. We can do better than that with our knees, and we do very time we climb stairs. The big deal is maintaining that kind of acceleraton for long distances and time periods. But seriously, when you're using nuclear power, the long time frames and distances are of no concern. The Sun has maintained for billions of years, performing the same reactions for dozens of hours is not the technical hurdle.

-Frank
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