Mesh Archive: Reverse Engineering Questions

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root root's picture
Mesh Archive: Reverse Engineering Questions

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root@Mesh Archive: Reverse Engineering Questions

I've put this Archive in with the Philosophy Archive, using the same horrendously expensive QE messaging system. Up-rates for my efforts are appreciated. Come here when you need someone to explain the math behind some of the more puzzling accomplishments of h-corp engineers. We, the @-rep hackers, will try and work out what the physics would have to be to accomplish some of these toys.

Surya: What distance from Sol do these things have to orbit such that the solar energy collected is enough to power the magnetic fields needed to avoid death by radiation? At this distance, how much energy has to be diverted to move against the Solar Wind to keep orbit distance? Given the gravity well of Sol, can the Surya ever come back from their orbit?

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nezumi.hebereke nezumi.hebereke's picture
Re: Mesh Archive: Reverse Engineering Questions

>What distance from Sol do these things have to orbit such that the solar energy collected is enough to power the magnetic fields needed to avoid death by radiation?

Given that they're using radiation to defend against radiation, I'm going to go out on a limb and guess that at no point will the energy gathered from the Sun be less than the amount necessary to defend from the radiation from the Sun (although eventually it will be too little to support life functions. I couldn't guess at what point that is.)

> At this distance, how much energy has to be diverted to move against the Solar Wind to keep orbit distance?

The amount of energy required to maneuver is going to increase as they move away from their optimal 'altitude', since they actually use the solar winds and solar 'atmosphere' for locomotion. This is similar to the problem airplanes have in atmospheres - as you go higher and the atmosphere gets thinner, you need a larger airfoil and, if using air-based propulsion, a stronger engine. Eventually they'll reach a point where the acceleration from solar winds is negligible and, without additional propulsion, they'll be effectively stuck at a single heading and speed. Worse, since their metabolism depends on that solar radiation to live, they'll basically starve. However, since we aren't given any real numbers on them to begin with, even the basic ones such as mass, speculating on how much energy they need for particular maneuvers is impossible.

(I would assume that they are able to streamline themselves so they have little or no resistance to the solar winds, and so if they've found a good altitude, they can control it pretty effortlessly.)

>Given the gravity well of Sol, can the Surya ever come back from their orbit?

I *believe* that solar winds lose power on a pretty standard logarithmic formula, similar to eletromagnetic radiation. Whereas, if memory serves, gravitational energy steps off at closer to a cube root calculation (an actual physicist can correct me on the numbers - the core of it being that EM is strong force, and gravity is weak). That means that a Surya can escape the Sun's gravity well. Because the solar winds are in fact particles, and they are unevenly distributed, this would suggest that:
a) There are dips and currents that can be taken advantage of. Move into a dip and the gravity pulls you in deeper (or again, just pull in your fins so you don't catch as much solar wind).
b) Bernoulli's theories still apply and a surya can form its fins like wings to cut through the wind at an angle, create different pressures within the particle waves, and basically tack upwind like a sailboat. However, once you get too far out of the gravity well, getting back down may be much harder than getting up.

root root's picture
Re: Mesh Archive: Reverse Engineering Questions

root@Mesh Archive: Reverse Engineering Questions

nezumi.hebereke wrote:
>What distance from Sol do these things have to orbit such that the solar energy collected is enough to power the magnetic fields needed to avoid death by radiation?

Given that they're using radiation to defend against radiation, I'm going to go out on a limb and guess that at no point will the energy gathered from the Sun be less than the amount necessary to defend from the radiation from the Sun (although eventually it will be too little to support life functions. I couldn't guess at what point that is.)

> At this distance, how much energy has to be diverted to move against the Solar Wind to keep orbit distance?

The amount of energy required to maneuver is going to increase as they move away from their optimal 'altitude', since they actually use the solar winds and solar 'atmosphere' for locomotion. This is similar to the problem airplanes have in atmospheres - as you go higher and the atmosphere gets thinner, you need a larger airfoil and, if using air-based propulsion, a stronger engine. Eventually they'll reach a point where the acceleration from solar winds is negligible and, without additional propulsion, they'll be effectively stuck at a single heading and speed. Worse, since their metabolism depends on that solar radiation to live, they'll basically starve. However, since we aren't given any real numbers on them to begin with, even the basic ones such as mass, speculating on how much energy they need for particular maneuvers is impossible.

(I would assume that they are able to streamline themselves so they have little or no resistance to the solar winds, and so if they've found a good altitude, they can control it pretty effortlessly.)

>Given the gravity well of Sol, can the Surya ever come back from their orbit?

I *believe* that solar winds lose power on a pretty standard logarithmic formula, similar to eletromagnetic radiation. Whereas, if memory serves, gravitational energy steps off at closer to a cube root calculation (an actual physicist can correct me on the numbers - the core of it being that EM is strong force, and gravity is weak). That means that a Surya can escape the Sun's gravity well. Because the solar winds are in fact particles, and they are unevenly distributed, this would suggest that:
a) There are dips and currents that can be taken advantage of. Move into a dip and the gravity pulls you in deeper (or again, just pull in your fins so you don't catch as much solar wind).
b) Bernoulli's theories still apply and a surya can form its fins like wings to cut through the wind at an angle, create different pressures within the particle waves, and basically tack upwind like a sailboat. However, once you get too far out of the gravity well, getting back down may be much harder than getting up.

"If you would be so generous as to allow me to posit a question I don't have the math for yet, what do we consider the Sol orbit to be? We know that the Sun isn't a solid ball, it's a slow burning explosion that is shooting elements lighter than iron into the vacuum, and it creates a "wind" of particles racing away from it. The Solar Sail concept is based on the use of the solar winds, so it might be familiar from science fiction (I think Count Duku used one in Star Wars). Well, at some point the heliosphere ends at the heliopause, the border where the interstellular medium pushes back enough to stop the wind.

"I call the heliopause the borders of Sol, and I'm comfortable saying that there is some distance between the heliopause and the sun's surface, the surya can live in equilibrium. The question is "where?""

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root root's picture
Re: Mesh Archive: Reverse Engineering Questions

root@Mesh Archive: Reverse Engineering Questions

"I've got a piece of historical trivia for you all. I've dug up pre-Fall article from a mostly-trashed Archive I found hidden on a pile of ice in the Kuiper belt, and I was wondering what you thought of it. Here is the link to the page:

http://www.antipope.org/charlie/blog-static/2007/06/the_high_frontier_redux.html

"Translating the http protocol was a brief encryption game, if a little too easy. So, as a history lesson, how much did this guy predict correctly?"

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icekatze icekatze's picture
Re: Mesh Archive: Reverse Engineering Questions

hi hi

I will attempt to parse my stationkeeping data into common parlance. In regards to maneuvering by solar wind, I have the following entry on navigation via solar sail.

The basic method of determining thrust on an object due to solar radiation is to divide the intensity of light (in Watts per meter squared) by c (in meters per second). Doing this will result in a pressure (in Newtons per meter squared). The result is multiplied by the reflectivity value of the surface plus one (a valueless number between 0 and 1, with 0 being pure blackbody and 1 being totally reflective).

To generate an example, at 1 AU from the sun, the solar intensity is 1400 W/m^2. Dividing by c results in 3x10^8 m/s. Multiply by 2 for a totally reflective surface will result in a pressure of 9.3x10^-6 Newtons for a 1 square meter mirror. You can have your mirror floating stationary at any given point in the solar system by counterbalancing the gravitational force of the sun with the solar pressure. At 1 AU from the sun, the gravitational force on a 1 kg object is roughly 0.0059 Newtons. Some basic math will tell us that a 1 kg object requires approximately 632 m^2 of mirror surface to remain stationary. (or a square 25 meters on each side)

Solar intensity falls off using the inverse square law, for example as you increase distance by a factor of three, the intensity falls by a factor of nine. Gravity also follows the inverse square law, so no matter how far or close you are to the sun, a sail can stay the exact same size for stationkeeping purposes.

In regards to solar radiation and magnetic fields, using magnetic bottle technology, one could conceivable harvest solar hydrogen and use to to power a fusion reaction. The benefit of which is that solar radiation would also be effected by the magnetic bottle and could be diverted away from habitat areas.

Determining the accuracy of ancient predictions hardly seems like a efficient use of time, but in this case the results are tangentially relevant to my interests. This character is incorrect on several basic points.
• He is basing part of his travel time heuristic on the absolute most primitive drive type possible.
• He is basing part of his travel difficulty heuristic on a scale directly proportional to distance, when travel difficulty is more accurately determined by delta V required to achieve orbital distance or escape velocity in the case of interstellar travel.
• His pressure hull heuristic is based off of a space suit, which is massively less efficient due to flexibility requirements.
• Underestimates the human drive for self determination.
• Ten days of worldwide output with a 50% efficient propulsion laser does not count as a significant barrier given the distances involved.
• Assumes vessel will operate with a single stage.
• Is unaware that at the time his text was published, the Gobi desert was already colonized for the purposes of mining operations.
• Is unaware that with stone age technology the historical Berber ethnic group colonized the arid Sahara desert.

The solar escape velocity is only about 618,000 m/s, while .1c is roughly 29,979,245.8 m/s. At those velocities, distance is irrelevant to propellant requirements.

root root's picture
Re: Mesh Archive: Reverse Engineering Questions

root@Mesh Archive: Reverse Engineering Questions

"Hey folks, I've got another tech question for you. I'm trying to find the theoretical maximum data throughput for a signal. I'm looking for the information theory equivalent of the Carnot efficiency:

ηmax = 1 - (TC / TH)

There has to be a thermodynamic limit on lossless data transfer, but I'm having the damnedest time finding it.

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root root's picture
Re: Mesh Archive: Reverse Engineering Questions

root@Mesh Archive@Reverse Engineering Questions


"The Shannon Limit was the answer I finally found for that last one.

"I've heard that the galaxies in the universe appear to be accelerating away from each other, and that this movement necessitates a great deal of mass existing somewhere that we can't see yet. Well, wouldn't galaxies that were collapsing in on themselves see everything else as rushing away from them? If there are large black holes in the middle of each galaxy, then every galaxy will be collapsing, appearing to accelerate away from every other observation point.

"I'm not a physicist, I'm just trying to learn about the fundamental forces for my nanoscale projects. Apparently a (crude) metaphor for how nanites interact is like a bee dance. They communicate like tiny, mindless magnetic bumper cars."

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root root's picture
Re: Mesh Archive: Reverse Engineering Questions

root@Mesh Archive: Reverse Engineering


"Is it possible to tap geothermal energy from Luna? Geothermal energy requires tectonics, right? Or is it radioactive decay from the planet core? I'm trying to figure out how far down you could drill a 1000 meter radius hole before the heat stopped you."

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icekatze icekatze's picture
Re: Mesh Archive: Reverse Engineering Questions

hi hi

Beta@Titania: Geothermal

It is my understanding that geothermal energy can come from a number or sources, the only requirement is that the energy is stored in the ground material of a planet or planet like body. Any body that experiences a temperature gradient can be used to generate geothermal energy, and it is also my understanding that airless bodies are renowned for their surface temperature gradients. I love watching the infrared patterns, so pretty...

Where was I? Oh yes, thats right... I am no expert on lunar tectonics, but I have a feeling that the angle of repose for lunar material might pose a problem to any drilling attempts.

GJD GJD's picture
Re: Mesh Archive: Reverse Engineering Questions

JetSetMiner49 says:
"Most geothermal heat comes from radioisotope decay, thorium uranium and so on. Latent heat from the formation of Luna will have long ago dissipated. There is no evidence for plate techtonics on the moon, but it's been cratered and resurfaced many times that large scale regional vulcanism seemsto be the dominant geological process - the surface isn't so much shifting around as being remade. Plate techtonics is usually driven by geothermal energy, but the mechanisms are still poorly understood. Earth's techtonic activity was driven, it is thought, by convection currents in the upper mantle. Mars, on the other hand, with no plate techtonics, allows the monster volcanos of Tharsis and Elysium to form over hotspots in the mantle.

Luna is cold, though, geologically. It has a thick crust, thick, solid to semi solid mantle and small core, possibly divided into liquid outer and solid inner. It seems to still have some limited form of vulcanism ongoing, as limited ammounts of Irridioum isotope decay formed Radon have been detected in orbit - a gas which usually dissipates quickly unless replenished through outgassing from volcanic vents."

nick012000 nick012000's picture
Re: Mesh Archive: Reverse Engineering Questions

root wrote:
root@Mesh Archive@Reverse Engineering Questions

"The Shannon Limit was the answer I finally found for that last one.

"I've heard that the galaxies in the universe appear to be accelerating away from each other, and that this movement necessitates a great deal of mass existing somewhere that we can't see yet. Well, wouldn't galaxies that were collapsing in on themselves see everything else as rushing away from them? If there are large black holes in the middle of each galaxy, then every galaxy will be collapsing, appearing to accelerate away from every other observation point.

"I'm not a physicist, I'm just trying to learn about the fundamental forces for my nanoscale projects. Apparently a (crude) metaphor for how nanites interact is like a bee dance. They communicate like tiny, mindless magnetic bumper cars."

"Galaxies are accellerating away from us because the fabric of space is expanding. For an analogy, consider a balloon, with a bunch of dots drawn on it with a pen. When you inflate the baloon, the distance between the dots increases. The same principle applies; it's just that the surface of the ballon is three-dimensional instead of two-dimensional.

However, some galaxies seem to be moving in other ways, which indicate that they're being acted upon by an object beyond the boundary of our visible universe, which has been dubbed the Great Attractor. This means that from the perspective of a hypothetical person standing on the Great Attractor, they would see all the galaxies converging on them, but less slowly than they would have due to the expansion of the universe."

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