Of course it is about a rubble pile moon, but in a similar manner rubble piles may often be compose of materials from more than one object.
Quote:
https://www.sci.news/space/phobos-impac … 06445.html
This is an answer I am somewhat comfortable with, Quote:The study does not argue Phobos is made entirely of material from Mars, but the new results are consistent with the moon containing a portion of the planet’s crust, perhaps as an amalgamation of debris from the planet and the remnants of the impacting object.
I have some work to do on other topics and perhaps later I will look further. I also liked Terraformers post that referenced Hopp.
http://newmars.com/forums/viewtopic.php … 74#p155174
Quote:
Done
]]>I was thinking of creating a topic dedicated to rubble pile asteroids, since there seems to be confusion about the nature of such asteroids, and how best to work with them.
I found your topic here, and wondered if it contains any information along those lines.
The title is ambiguous and inclusive of such a wide range of topics that it may not contain any useful information.
If this topic contains any useful information about the nature of rubble pile asteroids and how to work with them, I'd appreciate your pointing me to a post to read.
(th)
]]>https://phys.org/news/2019-03-asteroids … ought.html
Sounds like even rubble pile asteroids may retain a big piece of the original core which may then draw the rubble back after a collision, hiding the core.
One possible nature of Phobos could resemble this, I am guessing.
Done.
]]>Some things I took away from it is that the magnets don't have to be cryogenic, or maybe I misunderstood. And space radiation problems are partially solved with it.
I will be back, with a shark....
Here it is, and it is in association with someone named Zubrin??? And what is this "Planetary Society". Sounds snobbish to me.
https://www.nextbigfuture.com/2017/09/i … rence.html
The "Z" associates with the "MuskTusk". I just don't think we know all things. We are given crumbs of information, and that is good, because it means that there may be something bigger. And I like the sound of that.
Anyway, while SpaceX appears to be working on a Rocket Jockey trip to Mars, which I do not mind. I hope they can pull it off, but there is this other material that suggests a different method, visiting orbit first, and I would say seeing what Phobos and Demos have to offer, but not forbidding Mars. And I will say will say two strange phrases "Ballistic Capture" and "Aerocapture" (With Plasma bubbles). I love it.
So, then lets do something, don't mind surprises.
Done.
]]>Here are a couple more links on its effect, just have not had the time to read through them...
https://opentextbc.ca/physicstestbook2/ … ional-emf/
https://opentextbc.ca/physicstestbook2/ … magnetism/
https://en.wikipedia.org/wiki/Electrodynamic_tether
Please review what I will say, and give me back what I need to improve my grasp.
Quote:
And that could suggest another toy. Perhaps part of Phobos could be constructed into a big space hab with lots of inertia, and it too could have a magnetic field and tether, but since it would be constructed of processed materials that are much stronger than a rubble pile, and since it would be smaller, perhaps it could fly down to 50-100 miles over the surface? Much smaller tether then.
For a tether, longer is better. If you're orbiting 100 miles up, you're moving at orbital velocity. If you're orbiting at 1000 miles up, a tether dropped down to 100 miles will be moving significantly slower than orbital velocity at its foot - it has the same rotational period around Mars as your counterweight, but the path is smaller. Which is why the required delta-V to dock with the tether is lower.
If the tether tip is only going at 0.6km/s, building a robust reusable rocket vehicle to dock with it would be a lot easier than building one that can reach orbit. The cost of getting stuff off Mars could get quite low. Maybe even enough that water could be economically mined from it (though I will hopefully ensure that's not the case, by undercutting such suppliers with my Cererean Water Company and our elevators).
Let me start by saying what I think you described.
Rotating Skyhook:
-A sub-orbital rocket launch. At its height it will be going slower than a circular orbit. In my view orbits have energy of altitude, and energy of motion. In a non circular orbit there is an oscillation where at the apex (Apogee) it will be moving slower than would a object traveling in a more circular orbit where altitude does not change. So, to grab it with a tether, I think you have to have a rotating tether, one that rotates in the same direction of circle that the flywheel/momentum anchor orbits. This then causes the tether hook end to have a better chance of connecting with the ballistic rocket at its apogee without intolerable differential speed. So the hook is traveling backwards relative to the direction of orbit. That must be sufficient in speed to compensate for a shorter tether.
Non-Rotating Skyhook:
Must be longer so that its hook speed will as I think you indicated match the rockets apogee speed at the point of interception.
Space Elevator as a Non-Rotating Skyhook:
And then we can probably argue that a space elevator is probably the longest sort of non-rotating skyhook we might care to think about. And probably not think about because for Earth and probably Mars it requires too much effort for the probable results.
…..
I am really happy about the work you guys are doing on Skyhooks for manipulating "Solid" objects. But I am of another sort on this. What I want to manipulate is Atmosphere, Ions, and Plasma if possible. So this could loosen or change the rules for the types of implementations that I want to try.
I think to begin, I will describe a atmosphere capture device. Should we lower a tube down into the thinnest heights of the atmosphere, we might get away with a fairly large differential speed between our "Hook" and the item we want to hook. If we only use vacuum from the top, that will do us no good. But lets suppose that we can send power through our tether and our tether is a serial set of tubes with air pumps between them. Or if you like maybe just one ram intake at the bottom so that even though you are at the high altitudes of the atmosphere, I will just say 50 miles, I think you can get what I am after. You could choose what works. On Mars that changes a lot.
So, you have this scoop, and a differential speed between the scoop and the item to pick up which is atmosphere. If you can pressurize the lower end of the tube-tether to 6 mb, then you can probably make the atmosphere rise more then 50 miles up the tube, as actually the gravitation will fall off a bit traveling 50 more miles up. And then so you would hope to condense this gas using any means possible. Compression or cold and Else. Maybe a combination. As you suck atmosphere up, your apparatus will loose orbital altitude and perhaps speed. My plan is to have a magnetic field that gets pushed by the solar wind, to give make-up energy to the whole process. The magnetic field will be throttled up and down, depending on if the wind is at your back (More Magnetic Field Then), or against you (Less Magnetic Field Then. It is even possible that you might manipulate the magnetic portions of the plasma of the upper atmosphere, with your magnetics. But that wanders from my current paragraph's apparent method.
Actually I am not that serious about the last paragraph. It is an interesting illustration of what I want, but I think real implementation will require a different sort of tether.
For now I can think of perhaps three methods to struggle with.
1) Lower a device on a tether, into the atmosphere, that will adsorb atmosphere into a substance. Pull it up and desorb the molecules, repeat. I am not so sure that is practical. Maybe with a rotating tether. It dips down adsorbs gas, rotates up, the you desorb the gas and somehow deliver the gas to a storage device. I suppose your device might be able to travel to the hub periodically for this delivery of gasses. I don't really think this is what I want, but it needs to be kept on a chalk board somewhere in the mind, for the possibility that someone will make a variant of it that could actually be practical.
2) Electrical Tethers: (I don't feel I have a full grasp of this, but I am interested in struggling with it further).
https://www-istp.gsfc.nasa.gov/Education/wtether.html
Here I think we might be dealing with Ions. If we suck ions up to the main body of the device electrically we will loose share orbital energy with the accumulated mass of the Ions. If we instead push Ions down electrically, we can boost the orbit energy. That is what I think so far. But I want to accumulate mass, I want (+) ions to travel up, I think. If that generates electrical power but puffs up the mass then I hope that that situation will be handled around Mars, by the modulated Magnetic sail of the parent device in the solar wind. We may get away with that for Mars and Venus, if we can surf/sail on the interface between atmosphere and solar wind. There is a problem though, as I want to collect this mass of electrically charged ions. That requires some further research, think. I am guessing it can be done, but if you are lifting up (+) Ions where do you get electrons for them? If somehow if you can lift up (-) Ions, then I suppose you can use an electron gun to shoot electrons at the lower atmosphere to get rid of them. I don't feel I have complete comprehension of what might go on with this. More is needed. And then if you electrically neutralize your ions to normal atmospheric gas, how do you compress this lean, thin substance? I have thought of https://en.wikipedia.org/wiki/Piezoelectricity. Piezoelectric actuators to compress gasses already attracted to a capacitive/Condenser surface. And that is as far as I have come on this one. Can anyone help?
3) If we are Surfing/Sailing on the interface between atmosphere and solar wind with a modulated magnetic field, then we might have access to upper atmospheric plasma, existing due to the space environment. A can we find a way to magnetically reconnect to this magnetic substance, de-energize it to gasses and compress it? That one is really at the edge of my comprehension so far. I do wonder about it.
……
Looking forward to feedback.
Done.
]]>Um....I am sure that the regolith of Phobos and Demos will require some cautions on toxic effects. It is conceivable that some perchlorates might be present. We don't know the exact composition of the parent bodies. Is there some other thing you want to draw attention to on this topic?
Life support is sort of an odd place for this except my aim in dealing with small bodies such as rubble piles, is to make them into life support machines of great complexity. I guess you could move this to some other section if you want to.
Done.
]]>And that could suggest another toy. Perhaps part of Phobos could be constructed into a big space hab with lots of inertia, and it too could have a magnetic field and tether, but since it would be constructed of processed materials that are much stronger than a rubble pile, and since it would be smaller, perhaps it could fly down to 50-100 miles over the surface? Much smaller tether then.
For a tether, longer is better. If you're orbiting 100 miles up, you're moving at orbital velocity. If you're orbiting at 1000 miles up, a tether dropped down to 100 miles will be moving significantly slower than orbital velocity at its foot - it has the same rotational period around Mars as your counterweight, but the path is smaller. Which is why the required delta-V to dock with the tether is lower.
If the tether tip is only going at 0.6km/s, building a robust reusable rocket vehicle to dock with it would be a lot easier than building one that can reach orbit. The cost of getting stuff off Mars could get quite low. Maybe even enough that water could be economically mined from it (though I will hopefully ensure that's not the case, by undercutting such suppliers with my Cererean Water Company and our elevators).
]]>Before undertaking this post, I ran a search on the forum for "perchlorate and harvest". That combination does not appear to exist, but there were several posts containing the word perchlorate, and one (by Void) which included consideration of exploiting perchlorate.
I'd like to toss into the hopper here the possibility of a full time full force mining operation to recover oxygen from perchlorate, and export the chlorine, or (perhaps) to find a non-injurious use for it.
This activity would (I presume) be carried out some distance from places of habitation. The export of oxygen would have economic value for sure, and it is likely someone will think of an application for the chlorine.
The activity of extracting perchlorate from regolith would (presumably) lead to economic activity related to other compounds found in the regolith, some of which (I gather) would also have economic value.
(th)
]]>Thank you for this (impressive to me) blog sequence from Hop David. Because I've been trying to understand how a tether might support sailplane excursions to the atmosphere of Mars to deliver or to pick up packages, I was interested to see that possibility mentioned.
A useful figure provided is a taper ratio of teflon for a tether of 11. I gather that that tether would reach to the surface of Mars.
The blog sequence also considers the eccentricity of Phobos orbit, and the presence of mountainous terrain along the equator of Mars.
This is a great find!
(th)
Some thoughts from Hop David on the potential of Phobos - http://hopsblog-hop.blogspot.com/2015/0 … solar.html
Cities have almost always, with the exception of the last century, grown up around transport nexus's. Perhaps the main employment on Phobos will be in handling cargo that's going between interplanetary space and the Martian surface. There might be other opportunities in that - shipyards, refuelling etc. Maybe even reconditioning for those going from Mars to Terra, who will have to spend some time in higher gravity than Mars can provide.
Lots of things moving through my head.
A thing I would want to include would be a "World" magnetic field for Phobos. This would serve many potential purposes. Radiation protection could be a benefit for the surface of Phobos. It might also tend to keep construction objects from be ejected into orbit. And I think a very big thing would be to be able to modulate/throttle the size of the field. In effect per the documents previous, Phobos is already the equivalent of a flywheel. We may be able to make it into a motor as well, by selectively sailing on the solar wind. This might allow PHobos to be sailed up or down in the Martian gravity well. Within the limits of it's safety.
I would also want to encompass the entirety of Phobos with a cage. It could be composed of electrical conductors, solar panels, struts, ect. And it might be something to attach tethers to. The cage then would also be a garage where you could service spacecraft and do construction projects, and perhaps some types of materials processing. The cage would also serve to reduce the amount of space junk that might get ejected to orbit. But you would want to consider the potentials for explosions. That could really mess up the Mars orbitsphere.
Certain environmental conditions could be controlled in that garage. The interior may have a moderated thermal environment. Lighting might be controlled. There should be some protection from micrometeoroids.
The magnetic field and tethers may each have the potential to extract gasses from the Martian atmosphere. I do not stand against those who see tethers for deploying cargos. They have covered that aspect well. One thing that I have some concern for would be that by dangling a tether into the Martian atmosphere, their could be electrical discharges.
That could be interesting though, if you could keep it from wrecking your machinery. That would be strange if you could get an electric current between the two bodies. The friction of your "Probe" in the atmosphere would then slow Phobos down in it's orbit. Also if you could capture atmospheric gasses from Mars to Phobos, that would lower down the orbit of Phobos. But since we would turn Phobos into a solar sailing motor, it could speed back up and climb to a higher orbit.
And that could suggest another toy. Perhaps part of Phobos could be constructed into a big space hab with lots of inertia, and it too could have a magnetic field and tether, but since it would be constructed of processed materials that are much stronger than a rubble pile, and since it would be smaller, perhaps it could fly down to 50-100 miles over the surface? Much smaller tether then.
As far as Phobos and Demos themselves, I am wanting to see if they would have needed materials. Rare Earths, Platnum Group and Gold, Water. And of course there should be common construction materials. Very likely they will contain fragments of the crust of Mars from long ago that will have value for science. Water could occur several ways. But Tars, and Clays seem like something that could be possible.
My thinking is that if Mars/Phobos/Demos gets going well, then more people and materials will arrive from the Earth/Moon. Then the empty cargo space going back might bring useful mined materials back to the Earth/Moon.
Mars is going to need some of those materials as well.
As for habitats in orbit, I still like a low g outer shell, with interior spinning synthetic gravity machines. I intend that each of them would have vacuum bells around them, probably just a bit larger than the spinning hab. The interface between the low g non spinning portion, and the spinning portions might actually just be a sort of airlock(s) at the rotation points. There would be air seals where the joins at the bearings would be. In this setup, even if the seals sprung a leak, the volume of the vacuum chamber would not be enough to cause deadly harm to the inhabitants.
…..
I am away that all of this is very grandiose. The picture painted is the a partially thought out version of a possible desired outcome. And so would be the Point "B".
But we need a Point "A" to start from as a "Seed Method", and that has to be able to grow and metamorphically evolve through many changes to achieve something like what can be suggested as a point "B".
Done.
]]>