Jeff M. Hopper
SOC-14 1K
Try throwing a several hundred pound chunk of ice at your car and see what happens.
I'd bet that a TL 9+ starship has a greater structural strength than my TL 8- car!
Ice Refuelling
- Thread starter Blue Ghost
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I'd bet that a TL 9+ starship has a greater structural strength than my TL 8- car!
Jeff M. Hopper
SOC-14 1K
How about just letting the tube lead to an empty tank and allow the liquid/gas expand to fill the volume? No sucking, just a flowpath with less resistance.
Jeff M. Hopper
SOC-14 1K
Well, for the methane burning, I was honestly thinking about the electrodes used during electrolysis. If you dissassociate methane using electrolysis, you will end up with a buildup of carbon on one of the electrodes which will foul it up eventually. If you burn the methane with the extra oxygen created, you get carbon dioxide and water, of which the water makes for easier electrolysis into hydrogen without the carbon buildup on the electrode.
You actually probably wouldn't have to be much more careful than if you landed on a planet with 'traditional' volcanism (i.e. you would want to be sure that the ground you are on isn't housing an ocean of liguid magma).
There's probably a small amount of extra care due to the tensile strength of ice being lower but I would imagine not a whole lot. If the planet has cryovolcanos everywhere spewing forth ice and methane then yes, you would definitely be careful, much as if you were landing on a planet where conventional volcanos were spewing forth magma left and right.
If you were landing on a planet where there was much lower incidents of cryovolcanic activity I would imagine it would be much like landing on a planet that has much lower incidents of volcanic activity, such as Earth. You would be careful if you were landing near areas exhibiting active volcanos but otherwise, it's probably not a big deal.
Remember that to the cryocreatures of Deneb IV who evolved in an ocean of liquid methane Earth is a hellish planet with vast seas of molten ice that will evaporate and fall from the skies in a searing rain. In some ways it is all about perspective.
Heh, I remember reading that little blurb about the Denebians (though I forget which book it was in). To me it states that there is more than just "soft science" at work in Traveller, and that there is in fact potential for more hand waves to bring some true science fiction to Traveller.
Cryovulcanism is particularly interesting since, as you say, there is a certain dimension of perspective at work here; i.e. relative temperatures extolling the same physical phenomenon for matter in different realms of exited states. Which could create a potential danger for a starship low on fuel, and looking to land on a Neptune or Uranus like world, hoping to score some cheap fuel.
I recall from Azhanti High Lightening that the effects falling into the fuel tanks filled with liquid Oxygen or Nitrogen was instant death. It makes it that much more critical that your piloting and navigational skills to find a nice patch to land on, be exceptional. And weather could also be a factor. Landing on a relatively calm world like Uranus will be challenging enough. Landing on a world like Neptune, with the system's fastest clocked winds, will make refuelling "by hand" that much more difficult.
Has anyone ever shoveled snow in a blizzard?
You would not want to attempt to land on an Ice Giant (i.e. a Uranus-like or Neptune-like world). Although they are called "Ice Giants" astronomers employ many terms differently than we normally do in everyday usage. An "ice" in astronomical usage is any volatile substance heavier than hydrogen or helium. It has nothing to do with temperature or state of matter. The "ices" on Uranus, for example, are a hot, dense fluid-mantle composed of of NH3, H20, and some other volatiles, under high pressure. This water-ammonia "ice" ocean surrounds a dense rocky core.
http://en.wikipedia.org/wiki/Uranus - See: "Internal Structure"
http://en.wikipedia.org/wiki/Ice_giant
Skimming the atmosphere would be a different matter, but the point of the OP is that we are avoiding that maneuver.
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Do you have a link other than Wikipedia, or a book source?
I could probably see if I can track an additional reference down, if you would like. But the information I noted above is fairly mainstream within the astronomical community.
To me "molten" describes a kind of sludge derived from a solid because there's a lot of free flowing energy in the system. I've seen lava, molten rock, but I've never seen a molten form of water; i.e. "ice sludge". I guess technically I've seen slurpees and other ground up ice mixed with water, but I've never seen a natural molten form of ice of any kind.
Again, 1st point is that you need to remember how astronomers define the term "ice" within their discipline: a volatile substance heavier than hydrogen or helium. So both NH3 and H20 are considered "ices", regardless of whether they are in solid or liquid form, and regardless of temperature. It is somewhat similar to how astronomers use the term "metal" in reference to stars: any element within a star heavier than hydrogen or helium is called a "metal", and the proportions define the star's "metallicity". Therefore, to a stellar-astronomer, oxygen and nitrogen are both "metals" as far as they are concerned, even though from a chemical/molecular standpoint they are nothing of the kind. It is a shorthand term for describing heavier-elements. The same is true for "ices" in planetary contexts: it is a shorthand-term for describing volatiles other than hydrogen or helium.
In reference to your quote above, it has to do with the pressure and temperature that the volatiles are under. It creates abnormal states of matter that we are not normally accustomed to at the temperatures/pressures at which we live.
From two Science News article abstracts (unfortunately you need a subscription to view the full articles):
In reference to your quote above, it has to do with the pressure and temperature that the volatiles are under. It creates abnormal states of matter that we are not normally accustomed to at the temperatures/pressures at which we live.
From two Science News article abstracts (unfortunately you need a subscription to view the full articles):
Obviously, there are a range of possibilities suggested by these titles, but note that in neither case is cold snowy-ice in view in terms of H20.https://www.sciencenews.org/article/water-world-extrasolar-planet-loaded-hot-ice
Water World: Extrasolar planet is loaded with hot ice
by Ron Cowen
10:10am, May 16, 2007
Astronomers have found a Neptune-size planet outside the solar system that's composed mainly of water—albeit in solid form. With a torrid surface temperature of 600 kelvins, the planet can't support life. But its existence bodes well for finding watery planets that could provide a haven for life, say Frédéric Pont of the Geneva Observatory in Sauverny, Switzerland, and his colleagues, who report the discovery in an upcoming Astronomy & Astrophysics Letters.
PLANET UNDER PRESSURE. Proposed structure of an extrasolar planet that may contain hot water that remains solid under high pressure.
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Also note: Though you would not want to attempt a landing on the "surface" of an Ice-Giant (Neptunian) world, such worlds are invariably orbited by small ice-moons, where the volatiles are ices in the forms we are more familiar with (cold/snowy/"icy", etc). A non-skimming refueling operation would likely be conducted there, rather than the Ice-Giant itself.
esampson
SOC-13
The technical definition for molten is 'liquefied by heat'. In more practical use we tend to associate that with materials that we do not normally see in a liquid state. Thus we will talk about molten rock, molten steel, etc. while not talking about 'molten water' or 'molten mercury', but rest assured that it is a proper definition.
Of course to creatures who exist at temperatures where ice is almost never liquid water at 0 degrees centigrade would be much the same as basalt or iron at their respective melting points; something which they almost always see as solid but with tremendous heat is turned into a liquid state.
In fact it might be an interesting mental exercise to imagine a race of such beings melting ice, pouring it into molds where it cools into the desired shape. For a moment I was thinking about them trying to forge things from ice but I realized that ice almost certain lacks the properties that would allow that and it would be like trying to forge rock, as opposed to iron.
But gravitic drives (thrusters) are the ones most used in starships. Reaction drives are only used at lower TLs (of course, MgT 2300 AD excepted
).
esampson
SOC-13
While the atmospheric pressure is well below the triple point the water vapor itself will provide atmospheric pressure. Now I'm not at all certain how quickly that pressure will dissipate, but there may be enough time during which the atmospheric pressure is in the range of .1 bars and there is liquid water.
Most likely there won't be. You could try various tricks to contain a partial atmospheric pressure (a domed tent over an air/raft radiator) which would allow the water to remain liquid, but honestly I would probably just look at scooping up the water vapor that you released. No doubt you will only get a tiny fraction of what you melt, but you shouldn't have much difficulty melting the ice and there's so much of it that a tiny fraction is all you need.
esampson
SOC-13
There's nothing that says a gravitic drive is not a reaction drive (with the exception of MT).But gravitic drives (thrusters) are the ones most used in starships. Reaction drives are only used at lower TLs (of course, MgT 2300 AD excepted
esampson
SOC-13
Actually, I pretty much made up the specific example of the Denebians on the spot.
I'm sure, however, that more than one sci-fi author has created fairly detailed creatures that come from a super-cold climate and probably with that same point of view.I first realized the arbitrary nature of how we view things like that a few years ago when a new exoplanet was discovered and people were postulating that it was so hot that it would 'rain molten rock'. I read that and thought 'huh. And is that really so different from Earth where it occasionally rains molten ice?'.
esampson
SOC-13
To be technical a reaction drive means it obeys Newton't third law (for every action there is an equal and opposite reactions). It is possible in a sci-fi setting for a gravitic drive to be reactionless; the ship simply lifts off without any interaction with anything else.
Most visions of gravitic drives, however, are probably not reactionless. At the very least there is a force exerted directly between the ship and the planet. As the ship moves in one direction the planet is moved in the other. Of course since the planet outmasses the ship by tens of orders of magnitude the motion the planet makes is unmeasurable for all practical purposes.
That said, the only real definition of 'gravitic drive' is that it is a drive that interacts with gravity. A propeller might be viewed as an 'atmospheric drive' in a similar fashion. It interacts with the atmosphere and creates a force that moves the plane forward. In doing so it also creates force that extends away from the back of the plane (prop wash). In a similar vein a gravitic drive could have a 'thrust' of some form that is dangerous to be in. Maybe it is just a form of gravitational energy that can mess up matter passing through it. Maybe the gravitational drive produces elementary particles through the disruption of quantum perturbations similar to how a black hole creates Hawking radiation through it's immense gravity.
In a different thread we referred to whatever streams out of the back of a gravitic drive (assume such a thing happens) as 'thrustons'. It doesn't matter precisely what they are. The real answer is you don't want to get blasted by it.
This doesn't mean that gravitic drives must behave this way. It is entirely possible to have one of the first two versions I outlined (reactionless and reaction) which would create an environment in which people could stand right next to a launching ship. All it means is that when you look at a version of Traveller (or any sci-fi for that matter) and all it says is 'gravitic drive' that doesn't mean it is reactionless and without exhaust.
It is the 3rd Law: For every action there is an equal and opposite reaction.
Rockets use this principle. "Grav drives" either "push" against an existing large mass. Like a planet. Or, in the case of deep space grav drives that don't have efficiency drop off, create their own grav field for the ship to "fall" into. The 2nd definition is NOT a reaction drive. The 1st type of Grav drive is not either but one can make torturous semantic attempts to make it so.
MT's Thrust Plates: "Upon reaching TL 11, breakthroughs in quantum physics leads to REACTIONLESS thruster plates. Faster and more efficient than grav propulsion systems" (they aren't Grav drives)...
esampson
SOC-13
Actually, both version are in fact reaction drives. In the first case the action/reaction is with the planet. This is no more semantic that pointing out that a car obeys Newton's third law and so is not reactionless.
In the case of the second example, unless the gravitational field created only interacts with the ship then it will interact with other matter in the universe which would then function as the reaction mass.
MT's thrust plates on the other hand truly are reactionless because the ship moves without outside interaction (the plates being part of the ship).
This is no more a 'tortured semantic' than saying a rocket motor is not a jet engine. The two have similarities but also very precise, functional meaning.
I think the true core of our disagreement, however, comes from your definition that a gravitic drive works either one of two ways. Unless more detail is presented in setting the only thing that can be safely said is that they work through the actions or interactions of gravitational fields.
To be specific, MT had both Gravitic Drives (TL-10), and Thrusters (TL-11). The Gravitic drives were fully-functional out to 10 diameters (dropping to 1/2 efficiency beyond that IIRC), but the Thrusters had no such limitation. The Thrusters in MT, however, were described by DGP in SOM as being based on the "Strong Nuclear Force", not gravitics, and they "pushed against" their own Thruster-plates.
Hence, in MT uniquely, Thrusters were a truly "reactionless" drive in the Newtonian sense. Thrusters in later versions of Traveller did not keep the connection to the Strong Nuclear Force (in T4 they were related to gravity again).
In T5, we have two gravity-based drives: The G-Drive (good out to 100 dia) and the M-Drive (good out to 1000 dia). But there is a brief mention at the top of the page in the introduction to Maneuver Drives that mentions other drives for which the T5 book did not have have enough space to be included, in which list is mentioned "the Thruster". (?)
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