There are apparently other ways humans have done this as well:
>"The Cold War tests, which detonated explosives at heights from 16 to 250 miles above the surface, mimicked some of these natural effects. Upon detonation, a first blast wave expelled an expanding fireball of plasma, a hot gas of electrically charged particles. This created a geomagnetic disturbance, which distorted Earth's magnetic field lines and induced an electric field on the surface.
Some of the tests even created artificial radiation belts, akin to the natural Van Allen radiation belts, a layer of charged particles held in place by Earth's magnetic fields. The artificially trapped charged particles remained in significant numbers for weeks, and in one case, years. These particles, natural and artificial, can affect electronics on high-flying satellites—in fact some failed as a result of the tests."
https://phys.org/news/2017-05-space-weather-events-linked-hu...
Clearly one of Elon's Red Dragon missions should deploy a VLF antenna and measure cockpit radiation with and without the antenna broadcasting. It would be a real breakthrough if we could deploy 'shields' in this way that would protect interplanetary travel.
Antenna size alone shouldn't make them particularly hard to use in space. While there are forces acting on the antennas from the fields' interactions with deflected particles, it's not like trying to move a square mile array at high speed through a dense medium like the atmosphere (which of course is not a thing we do on earth - transmitters are static). Submarine receiving antennae are just great big long straight wires which would be even easier in space.
Mass will be a factor given their probable need to handle high current loads; packing and unfurling seems to be a thing we can do quite well; stabilizing them and keeping them in the correct orientation as the ship accelerates and the fields deflect particles could be really hard or quite easy, I have no idea.
In space you need no supports. A 2km dipole using essentially two conductive mylar 'tubes' inflated with a small volume of gas could easily fit within the RedDragon's trunk.
True, although that would limit which polarization options were available to you. I am also presuming that the inverse square law is helping here in that you would not need the kind of signal strength the antennae on Earth need to get through the ocean, rather just enough to create a Dragon sized bubble impenetrable to ionizing radiation at a distance of a couple of meters.
1. Is this the reason moon missions got a lower dose from the VA belt than expected?
2. Are we concerned about the long term decrease in genetic change from filtering out charged particles? Or it it only relevant to solar particles, not cosmic?
There may be a possibility that this could affect autoimmune disease. Incidence of Rheumatoid arthritis has mysteriously been correlated to the solar cycle and geomagnetic conditions.
As for (2), regardless of particle type -- we've been creating this field for, what, <100 years?
Genetic change of that type happens on a scale 3 to 5 orders of magnitude greater than that. If we maintain this field for another thousand centuries, then maybe we should start thinking about those kind of effects.
As to 3, reducing coal usage would do more. Coal has enough radioactive sulfur that Chinese pollution swamps the levels of radiation emitted by Fukushima, for example.
I was thinking the same about Jupiter - the space around Jupiter is horrifyingly radioactive because of charged particles. I wonder if a manned spacecraft could be protected from these particles with a VLF radio field?
Is that a correct use of the term 'radioactive'? I thought it referred exclusively to atomic decay. Although energetic particles probably induce radioactivity in some of the orbiting material when they collide... damage from that secondary radioactivity wouldn't be very much compared to the damage done directly by the high energy particles, would it?
You are correct. Radiation != radioactivity. Radioactive things give off radiation. Radiation itself is not radioactive. It's in the name: radioactive = radio-active = radiation (radio!) generating (active).
As was I — and also (because I'm not an astrophysicist so have no clue how ridiculous this sounds...) — would a much [, much, much] larger and denser/thicker version of such an array be of any use where a local supernova's concerned? eg. much further out and much, much broader, and deployed when there might be suspicion of such an impending event, from a known location?
I figured a far-off low level diversionary shield could act as a 'spike' and head off supernoval rays like some bow shock, but obviously that would be impossible to maintain a position as we orbit. Duh.
So, I guess the only even vaguely plausible shield we could have is a local one — some sort of massive heavy water density spray to absorb energies before they hit our atmosphere.. in the very vain hope.
I can imagine a plasma shield for interplanetary spacecraft would require a lot of power to run, which would then require even more equipment to radiate away the waste heat. That seems like it would come with a lot of potential failure points.
I wonder if storing water in a double hull would offer the same protection for less equipment/weight/risk?
Well, if you've got people on board, you're going to need lots of water anyway. I guess it depends on the cost of lifting mass out of Earth's gravity well compared to the cost of making a highly reliable plasma shield.
It's not just the lifting out of Earth's gravity; mass is a liability in all forms of space travel. For any sort of momentum transfer drive (i.e. all of them, barring a scifi breakthrough like reactionless or warp), adding mass will eat into your delta-vee.
That's a good point, but system complexity and failure risk is also a liability that needs to be considered. A few meters of ice around your ship will be pretty much 100% reliable and require zero power, but for the considerable extra fuel required to achieve your required delta-vee. An ice-hull will also stop micrometeorites which I'd imagine a plasma shield would not be able to deflect.
Potential downsides of shielding the earth like this?
If life has evolved over billions of years with the assumption that such this radiation would be present, it may be disruptive for it be removed suddenly.
This is not really related to the topic but for anyone else wondering like I did for many years how this statement makes sense (given that it is usually used in a phrase meaning a single counter example proves the general case true for some inexplicable reason), the phrase actually means something else.
A single counter example can prove a general rule exists in conversation, because we don't normally isolate examples unless they're somehow special. For example, if you come to my house, and I point at one of the chairs and say "you can't sit in that chair" you would assume you could sit in one of the others even though I haven't said so.
The example on wikipedia is "parking is not allowed on Sundays", which would lead you to assume that parking was allowed on other days. As it says there, a more explicit wording would be "the exception that proves the existence of the rule."
That's an interesting interpretation, but I was under the impression that the word "proves" was meant in its older sense as "tests". The phrase "the exception tests the rule" would convey the same "well, if you have to call out an exception, that means that the rule is otherwise operative" meaning you ascribe to it, but I think the etymology supports it better.
The phrase "exception that proves the rule" is from the Latin "exceptio probat regulam in casibus non exceptis," or "the exception confirms the rule in cases not excepted." The Wikipedia article[0] is actually pretty interesting, and among other things suggests that your interpretation of "proves" as "tests" is false.
I always understood the saying in the statistical sense. That is, having seen – and understood – an exception, we can be more confident that our understanding of the rule is valid.
E.g., say the "rule" is, the database always keeps data safe. I might not feel confident about that claim, until I see a case when the database fails to keep the data safe, and understand exactly how and why the rule did not apply in that scenario. If I never see such a case, I have little confidence that we correctly measure whether the database keeps the data safe.
My first thought: maybe we will live longer because of less cancer from those charged particles? Our nuclear subs are helping us live longer!
My second thought: those particles are essential for mutagenesis, which is a primary driver of evolution, not just in us but everything. The sixth great species extinction we are causing is not enough, we're literally living in an evolutionary bubble, decreasing the likelihood that whatever survives us will be able to adapt over millions of years.
You don't need to worry about that second one. The rate at which mutations happen is itself controlled by evolution, through some pretty sophisticated mechanisms, and if it drops that way it'll just adjust itself right back up.
