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Post by rmc on Oct 15, 2015 23:55:02 GMT
Right, the light works.
Cyber, there are basically two models on the table, as it were. One has a 0.6 percent atmosphere constructed similar to Mars's gases, etc, where a fan would be built to drive winds to 60 mph or 100 mph, likely needing a fan that has been redesigned in order to drive the thin "air". The other model includes a total vacuum where ferromagnetic dust is driven toward an electromagnet to test the amount of force provided. Each has some analog for the dish antenna and is rigged to reveal how much force is imparted onto it. Keeping track of how much resisting force (traction) there would be is another issue that has a couple of possible work arounds: Hang the umbrella by wire, or drop the whole chamber like an elevator.
Dust in wind, or anything launched by fluid actually, has a particular thing that happens. Basically, the particle is given an impulse from the surrounding fluid, by which the particle looses traction with the ground, launches into the sky, and races up to the speed of the fluid in question (if the wind force is consistent enough). Once at the same rate as the surrounding fluid, however, the particle no longer has the lift or imparted force to keep it aloft, since both the wind and the particle are going the same velocity (there is essentially little to no relative wind at that moment), gravity is left to do its thing and the particle begins to descend. This isn't immediate, and can take time for it to lose altitude since wind forces are not always constant (the variance can impart new impulses along the way). Once back on the ground, traction takes over briefly just until the differences in velocities between particle and the surrounding wind imparts another impulse, launching it back into the air. This cycle wholly depends upon how large the particle is. For fine, fine dust, the cycle can last quite a while and altitudes can get extremely high before falling, again due to wind velocity variance. I've seen this effect working on a plastic bag. The bag was swept up, and went very high, almost violently. But, over time it seemed to get lazy while carried along in the wind, and slowing fluttered lower and lower, even as the wind howled on.
Keeping a particle airborne on a planet with 2/5ths Earth's gravity may be simpler than some consider. Also, however, the amount of force involved to make it airborne is less too, thereby meaning the amount of force such particles impart is likely less as well.
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Post by silverdragon on Oct 16, 2015 7:30:13 GMT
*Coughs* Could someone explain how you'd get a fan to move air in a vacuum? Dust storms do exist on Mars, and regardless of the actual size of the particles or their speed (which would have to be high enough to keep them airborne anyway) the impact of those particles would significantly increase the amount of force on any object they impacted. Vacuum chambers don not work at zero. (In fact getting a complete vacuum here on earth is pretty hard, I know of one space research centre with one that takes two days to suck all the air out of a two foot thick steel walled room?...) We are talking a partial vacuum of 1:100th 9or there abouts) of earths atmosphere?...
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Post by silverdragon on Oct 16, 2015 7:35:13 GMT
RMC, to expand, (all of us) We dont consider it easy, nor hard, to keep the particle airborne, we just are thinking inside the box?...
The maths are difficult. But we are managing them. The theory, we are discussing...
In all, I think we are getting somewhere here, its just being able to imagine a box that is not earth physics that we are used to, but martian physics, which non of us are?...
Except maybe Goldilocks (cyber) who may have visited there once to get some new hair dye....
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Post by rmc on Oct 16, 2015 11:24:35 GMT
Looks like NASA has done some of this: www.nasa.gov/centers/ames/research/exploringtheuniverse/vaccumchamber_prt.htmOur fan idea wasn't the way NASA approached the problem. But, NASa could not 'reduce gravity' because they used the giant, full-scale vacuum chamber and could not cause it to fall or whathaveyou. I originally was "all-in" on thinking this one through. And, reading everyone's input really got me interested in looking at it in new ways. Thank you!!! But, I have surgery November 5th to clear up issues I've been having since at least June. I was feeling okay about a week ago, but now symptoms have come back fairly strong. It could improve. Anyway, I might not be thinking everything out too well at the moment. So, probably a lot of what I've written above is hard to follow or not written well. Silverdragon, I remember approaching our physics instructor about the nature of the vacuum in the simple, small glass dome-type vacuum chamber in class. I assumed there would be trace amounts of gases left inside. After all, how could a motor pump every atom out of the container? She, however, insisted it was empty. I was not convinced and a bit surprised at her stance on this.
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Post by the light works on Oct 16, 2015 14:24:00 GMT
Looks like NASA has done some of this: www.nasa.gov/centers/ames/research/exploringtheuniverse/vaccumchamber_prt.htmOur fan idea wasn't the way NASA approached the problem. But, NASa could not 'reduce gravity' because they used the giant, full-scale vacuum chamber and could not cause it to fall or whathaveyou. I originally was "all-in" on thinking this one through. And, reading everyone's input really got me interested in looking at it in new ways. Thank you!!! But, I have surgery November 5th to clear up issues I've been having since at least June. I was feeling okay about a week ago, but now symptoms have come back fairly strong. It could improve. Anyway, I might not be thinking everything out too well at the moment. So, probably a lot of what I've written above is hard to follow or not written well. Silverdragon, I remember approaching our physics instructor about the nature of the vacuum in the simple, small glass dome-type vacuum chamber in class. I assumed there would be trace amounts of gases left inside. After all, how could a motor pump every atom out of the container? She, however, insisted it was empty. I was not convinced and a bit surprised at her stance on this. I am actually less than surprised. teachers often think in classroom standards, rather than real world standards. in the classroom, a vacuum pump pumps all the air out of a bell jar, bearings have no friction, and gravity is exactly 1G.
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Post by Cybermortis on Oct 16, 2015 19:11:17 GMT
Note; Adam is a huge fan of the Book (and I'd assume the film) and knows the author, who he interviewed for Tested earlier this year.
As such I think that it might be a good idea to try and develop ideas originating from the film and book (film first, since that A; would provide visuals for the show and B; Is much more likely to be known by the majority of viewers.) I'd be surprised if Adam hasn't raised the idea of doing stuff from The Martian already to be honest, so that would be at least one of the shows producers who would take such an idea seriously.
Their good relations with NASA might also make this a tempting notion, as they would be able to get a lot of technical information and specs for the type of dish seen in the film along with any other equipment used. Even if some of the equipment doesn't exist at this point, NASA would have both existing examples that could act as a basis for a theoretical design (if they don't already have such designs on paper already) along with knowing what kind of factors would have to be considered in terms of design. That in itself could add an interesting aspect to a 'Martian' special as they might be able to go and film existing equipment down at NASA. I'm sure NASA themselves would LOVE such publicity.
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Post by rmc on Oct 16, 2015 20:47:19 GMT
Above: A vacuum chamber is constructed with electromagnet, pictured left end, and a shelving system, carrying small quantities of ferromagnetic dust (unknown type of dust at the moment), and a wire-hung analog for the antenna dish between. A camera is hung to view contents in action (not shown) Above: The vacuum chamber is rigged to roll down a ramp. And the releasing means includes a switch that will switch on the camera, the electromagnet and allow the cart to roll down all at the moment the releasing switch is thrown. The angle of the ramp would be calculated such that the fall best replicates 2/5ths downward earth acceleration (Making a kind of Martian Gravity for the experiment) This Martian Gravity component is something missing in the NASA experiment, by the way...
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Post by silverdragon on Oct 17, 2015 8:42:37 GMT
So am I!... For a start, those small glass domes rely on a rubber seal to seal them up if I remember right, and those seals have a failsafe of getting sucked in if the pressure gets too great. Secondly, I dont know of a single across the counter engine that can make a complete vacuum.... not in that way. Specialist piston engines "Come close", but not a true vacuum....
Lastly, the glass would break.
You have the pressure differential of more than the Marianas trench on a true vacuum dont you?... and the glass [or perspex] windows on the submersibles that explore that are a foot thick at the least.
BTW, That nasa chamber is the one I was referring to....
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Post by silverdragon on Oct 17, 2015 8:56:58 GMT
Good thinking on that.
But... for TV, may I suggest another method that may be a bit more TV spectacular?... use/dont use as it goes further in theory?.. The Vomit Comet. Get that to "dive" in a way that allows a low gravity. You can then expand that to an even lower gravity, or zero gravity, to vary the results?.. You can suspend a weight on a "fish scale" type scale inside the tank to indicate the amount of relative gravity acting on the experiment.
Take the pressure vessel up into the clouds and have it run whilst in a dive, with a camera angle wide enough to see Jamie doing the commentary and Adam bouncing about like a rubber ball..... I know he would enjoy it.
Expand the vessel to a long 4ft fish tank [or longer if you can get one...] with fan at one end and a base filled with light sand, see if the fan can even pick up the sand?.. duct the fan to pick up at the far end to return via the top of the tank to the fan to stop swirling about and allow just a smooth flow of air acting on the sand.
I am having fun with this one, even if my suggestions dont get used.
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Post by silverdragon on Oct 17, 2015 9:00:17 GMT
I have a question that may/may not have relevance. Atmosphere. Does the size of the atoms make a difference?. The thinks on this...If the Martian atmosphere was say pure hydrogen, the hydrogen atom is smaller than heavier gasses, so may not have enough mass to act on "sand".
Or is this over thinking the problem?.
What is the typical atmosphere on Mars?.. I doubt it has that much oxygen in it, but what is it anyway?. Anyone know for sure?. Does it make any difference at all?...
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Post by rmc on Oct 17, 2015 9:02:20 GMT
About seven tons per square inch at 35,000 feet deep below sea level. Thats way more than 15 pounds per sqr inch here at surface. So, no, the glass jar woundn't break if all of 15 psi were against the outside.
PS: those diagrams above are total CARP!!
no ramps! Those impart side to side acceleration! Must drop straight down.
And, vomit comit has all sorts of accelerations too. No good. The platform may have spin, swing and other acceleration besides the drop. So, even that aint perfect.
So, using the big NASA chamber, have a rig that drops from height, having electromagnetic "gun" firing a mass of dust at umbrella-like dish antenna that is pushed into Buster. If Buster flies, then merit to the scene in movie.
I'll try to sketch that. Sure, it is a big platform, but it is what it is. Oh, and done in vacuum, firing a powder repulsed by electromagnetism, not drawn.
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Post by rmc on Oct 17, 2015 9:05:31 GMT
No oxygen in Mars atmospere that ive heard, mainly CO2. I'll check
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Post by silverdragon on Oct 17, 2015 9:06:28 GMT
Only at the start and end?... You forget Inertia dear boy?. Its not as if the Planet Mars is NOT travelling through space already at a couple of thousand mile per hour?..
So start it descending, then after a [mili-]second or two, start the experiment... Yeah, longer ramp, and thats about all you will need?..
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Post by rmc on Oct 17, 2015 9:08:40 GMT
No. The ramp imparts CONSTANT acceleration. One component down, the othe side to side... Trig stuff
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Post by silverdragon on Oct 17, 2015 9:28:05 GMT
No. The ramp imparts CONSTANT acceleration. One component down, the othe side to side... Trig stuff Then you have to have a descender brake on it to allow a constant speed. A simple cog and a small speed retarder would work?... or attach all wheels to electric motors with back EMF braking if you want to get complicated. I like your idea BTW, it could be made to work.
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Post by rmc on Oct 17, 2015 10:36:25 GMT
Well, no. Need to convert from a constant downward gravitational acceleration of 9.8 meters per second squared to 3.9 meters per second squared. A ramp might do that, if at the correct angle, but there would be the side to side acceleration still. Dropping down would work, but involves pulleys ropes and counter weight of roughly half the platform weight or maybe almost 3/5ths counter weight to get the desired downward 2/5ths of Earth's downward gravitational acceleration.
But, if some smaller vacuum chamber is used, hanging Buster by wire and reading how high he goes after impact, using Earth's gravitation instead, could work in a pinch - need to recalculate for Martian gravitation, plus you don't have the same static friction (traction) you would on Mars, so dust leaves the gun sligtly differently. Anyway the big questions are: how much dust? What mass? What final velocity? Things like that before anyone could really start much of anything.
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Post by the light works on Oct 17, 2015 10:45:40 GMT
So am I!... For a start, those small glass domes rely on a rubber seal to seal them up if I remember right, and those seals have a failsafe of getting sucked in if the pressure gets too great. Secondly, I dont know of a single across the counter engine that can make a complete vacuum.... not in that way. Specialist piston engines "Come close", but not a true vacuum.... Lastly, the glass would break. You have the pressure differential of more than the Marianas trench on a true vacuum dont you?... and the glass [or perspex] windows on the submersibles that explore that are a foot thick at the least. BTW, That nasa chamber is the one I was referring to.... hard vacuum at sea level only has about the same pressure as sealing a jar at sea level and then sinking it to 33 feet. one atmosphere.
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Post by the light works on Oct 17, 2015 10:50:38 GMT
Well, no. Need to convert from a constant downward gravitational acceleration of 9.8 meters per second squared to 3.9 meters per second squared. A ramp might do that, if at the correct angle, but there would be the side to side acceleration still. Dropping down would work, but involves pulleys ropes and counter weight of roughly half the platform weight or maybe almost 3/5ths counter weight to get the desired downward 2/5ths of Earth's downward gravitational acceleration. But, if some smaller vacuum chamber is used, hanging Buster by wire and reading how high he goes after impact, using Earth's gravitation instead, could work in a pinch - need to recalculate for Martian gravitation, plus you don't have the same static friction (traction) you would on Mars, so dust leaves the gun sligtly differently. Anyway the big questions are: how much dust? What mass? What final velocity? Things like that before anyone could really start much of anything. the vomit comet manages its trajectory so as to minimize lateral acceleration. a set of control masses could show that they have the correct trajectory to get mars gravity without shimmying about.
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Post by Cybermortis on Oct 17, 2015 14:23:33 GMT
Some observations;
Ferromagnetic 'dust' or not, an electromagnet isn't a practical way to duplicate/create a dust storm. Magnetic forces fall off very quickly so in order to pull the 'dust' over any real distance you'd need something like an MRI scanner - Which as MB showed is 'only' strong enough to pull a box filled with an iron solution into itself from around three feet from itself. Besides which such a set up isn't actually going to duplicate a dust storm as the 'dust' would be accelerating towards the magnet rather than being slowed.
The atmosphere on Mars is mainly CO2, this may or may not have an affect on how dust behaves or how much force the wind might actually impart on something it hits. (Since CO2 is heavier than O2, N2 etc). So air pressure on its own could be misleading in this case.
A couple of hints...well more like twitching of the fur...from the Bothan makes me suspect that it would be worth trying to find more ideas from The Martian, as it appears as if there is some interest there. Not a huge surprise given what I said about Adam earlier.
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Post by the light works on Oct 17, 2015 15:30:05 GMT
Some observations; Ferromagnetic 'dust' or not, an electromagnet isn't a practical way to duplicate/create a dust storm. Magnetic forces fall off very quickly so in order to pull the 'dust' over any real distance you'd need something like an MRI scanner - Which as MB showed is 'only' strong enough to pull a box filled with an iron solution into itself from around three feet from itself. Besides which such a set up isn't actually going to duplicate a dust storm as the 'dust' would be accelerating towards the magnet rather than being slowed. The atmosphere on Mars is mainly CO2, this may or may not have an affect on how dust behaves or how much force the wind might actually impart on something it hits. (Since CO2 is heavier than O2, N2 etc). So air pressure on its own could be misleading in this case. A couple of hints...well more like twitching of the fur...from the Bothan makes me suspect that it would be worth trying to find more ideas from The Martian, as it appears as if there is some interest there. Not a huge surprise given what I said about Adam earlier. keeping that in mind about the limitations of magnets, you lose the gravitation aspect with it, but one could try dropping dust, possibly in partial vacuum, to get impact force, or propelling the dust with a burst of CO2 in a vacuum chamber. - assuming we can't get the results with a fan. a more complicated idea would be to use some form of linear motor with bismuth dust.
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