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This topic is inspired by a topic recently created by veteran moderator RobertDyck, to discuss Low Energy Plasma.
The Van Allen Belt is a region filled with Low Energy Plasma.
In the topic created by RobertDyck, Calliban has been describing a family of propulsion methods involving acceleration of plasma, including a category I have not previously seen considered. That category would be plasma created from regolith using high powered lasers applied to tiny particles of undifferentiated matter.
This topic is created expressly to offer a place for NewMars members to consider propelling a space craft inside the Van Allen Belt.
While this topic opens with a vision of a large fan sweeping across the ions in the Van Allen Belt, the creative thinking of members may allow us to "see" possibilities no one else might have considered before.
There's a ** lot ** of mass circulating around Earth in the Van Allen Belt. That mass is conveniently rendered amenable to influence by electric and magnetic fields, so a non-matter "fan" of some kind might be able to accelerate a space craft smartly in that medium.
Update: Post #7 of this topic contains an estimate of the total mass of the Van Allen Belts.
The total mass appears to be so little that any kind of propulsion would be limited as well.
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This post is reserved for facts about the Van Allen Belt, and for links to posts that may be added to the topic over time, when those posts might be of particular interest to future readers.
Per Google:
Van Allen radiation belt - Wikipedia
en.wikipedia.org › wiki › Van_Allen_radiation_belt
A Van Allen radiation belt is a zone of energetic charged particles, most of which originate from the solar wind, that are captured by and held around a ...
James Van Allen · Van Allen Probes · South Atlantic Anomaly
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Ions trapped in the Earth's magnetic field could be used for braking, using some kind of magsail. This could be especially valuable for the large ship because it avoids the need for aerobraking which is frankly risky. To enter an elliptical orbit from interplanetary space, the ship must lose kinetic energy. Better to do that using a passive drag type mechanism than using propellant.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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For Calliban re #3
I regret having limited knowledge of the physics of the Van Allen Belt.
In thinking about it, I wonder why charged particles are dangerous in this context. It seems to me (not having thought about it before) that it must be velocity of the particles that makes them dangerous. A molecule (or atom for that matter) that is missing electrons is not inherently dangerous, so it must be (or I presume it must be) velocity that gives them the ability to penetrate matter that comes into contact.
Following up on your thought about ion braking, it would seem useful to head into the flow of ions, in order to maximize the braking power they might provide. Meanwhile, I presume the surfaces of the vessel are going to be encountering those charged particles at the combination of their velocity and the velocity of the vessel.
I wonder if there are studies (there ** must ** be studies) of the flow of particles in the Van Allen belts, because they are so important for military as well as commercial space flight planning.
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This is essentially the idea being proposed by Jeff Greason and collaborators building on ideas of John Slough:
NSS Space Forum - July 14, 2022 - Fast Solar Wind Sailing with Jeff Greason.
https://www.youtube.com/watch?v=00xyBT70sB4
Bob Clark
Old Space rule of acquisition (with a nod to Star Trek - the Next Generation):
“Anything worth doing is worth doing for a billion dollars.”
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For RGClark re #5 - thanks for your contribution to this topic ...
If you have time, and if this interests you, please evaluate the potential for harnessing the kinetic energy of the Van Allen Belt for propulsion.
I am thinking it might be like the Jet Stream, which commercial airliners routinely harness to accelerate their progress over segments of long haul routes.
A consideration is that "sailing" is a passive undertaking, in the sense that no energy is expended moving the sails. This topic is offered for the purpose of evaluating the potential to "sweep" the mass of ions in the Van Allen Belt, just as a propeller "sweeps" collections of atmosphere molecules and accelerates them toward the rear of an aircraft, thus imparting momentum to the particles, and providing forward thrust to the aircraft in accordance with Newtons's third law.
The sweeping mechanism would be magnetic as the primary mover, with electrostatic force along for the ride.
A cyclotron is an example of a machine that uses a combination of electric and magnetic fields to accelerate ions (such as protons) to high velocity.
A design for a vehicle that would navigate through the Van Allen Belts would use some combination of magnetic and electric fields. The purpose would be to accelerate the ions toward the rear of the vehicle, so as to impart some small momentum to the vehicle.
The challenges would be many, but the rewards might be significant, just as riding the jet stream is financially rewarding for the airlines that can take advantage of that natural phenomenon.
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I have opened an inquiry with ChatGPT4.
The opening session is available for review at this link:
https://docs.google.com/document/d/1tde … sp=sharing
The output of the opening session is a problem statement, revised and clarified to fit the circumstances at hand.
It is entirely possible there is NO solution to the problem posed.
On the other hand, there may be a solution.
Either way, the inquiry itself should be interesting to those who might wish to learn a bit more about the physics of interaction with a stream of ions. Such streams appear to be common in the Solar System, so a propulsion method that works on (or around) Earth should also work elsewhere.
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I asked Google to find any information there might be on the mass of the Van Allen Belts.
The NASA paper below contains an estimate ...
https://spacemath.gsfc.nasa.gov/weekly/5Page46.pdf
Generative AI is experimental. Learn more
The Van Allen belts
have a mass of 0.00018 kilograms. The belts are donut-shaped and have one-third the mass of a donut.Physics World
The Van Allen belts are zones of energetic charged particles
that orbit a planet's magnetosphere. The Earth has two belts, with the inner belt extending from 600 to 3,700 miles above the surface and the outer belt extending from 9,200 to 15,600 miles above the surface. The belts are made up of energetic protons, with the inner belt containing protons with energy exceeding 30,000,000 electron volts.
The Van Allen belts also contain antimatter, with some studies estimating that the belts contain 160 nanograms of antimatter. However, any antimatter captured is almost immediately destroyed.
What is the strength of the Van Allen belt?
What is the density of the Van Allen radiation belt?
volume (containing no belt particles) from the outer volume, practically speaking, it makes no difference numerically. This would not be the case if we had selected a much larger inner boundary zone for the problem! Van Allen belts in kilograms? M = 0.00018 kilograms.
The Mass of the Van Allen Radiation Belts
That is "not much" !!!
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I asked Google for the energy that might be estimated as contained in the Van Allen Belts:
https://agupubs.onlinelibrary.wiley.com … i003p01069
Journal of Geophysical Research (1896-1977)
Letters to the Editor
Maximum total energy of the Van Allen radiation belt
A. J. Dessler, E. H. VestineFirst published: March 1960 https://doi.org/10.1029/JZ065i003p01069Citations: 17
Abstract
It is the purpose of this letter to point out that the results of the spherical harmonic analysis of the geomagnetic field place an upper limit on the energy that can be stored in the Van Allen radiation belt. It will be shown that conservative figures indicate a maximum energy in trapped radiation of 6×1015 joules. Such an energy could be supplied, for example, by 5×106 electrons/m3 with an energy of 40 kev over an effective trapping volume of ×1023 m3(out to approximately 6 earth radii). These electrons would correspond to a flux of 6×1014 electrons/m2 sec.References
I don't know how this amount of energy compares to anything else, so would appreciate a comparison of someone has time to investigate.
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6E15J =1667GWh. That is about as much electrical energy as a large nuclear reactor will generate in about 1 month. So it is substantial as a store of energy, but it would certainly be possible to use it up.
I think the idea of an ionospheric magnetic drag chute is a good one. A large ship entering orbit would pass the Earth at a height of maybe 200km, losing just enough energy to put it into a highly eliptical orbit. Successive passes through the ionosphere would gradually reduce apogee. The ship could then expend a limited amount of propellant to lift its perogee out of the upper atmosphere. The advantage is that we don't have to line the entire ship with heat tiles. The magnetic drag chute is a net of wires which can be stowed in a relatively compact package. The same thing would work for Mars arrival as well. In both cases we need to dump the kinetic energy that the ship will pick up as it enters the target planet gravity well.
Last edited by Calliban (2023-12-18 05:29:24)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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