Magnetoshell Airocapture

Impaler · 2014-12-09 22:38:21

This novel new idea for capturing into Mars (or other planetary) orbits looks to have huge potential for reducing IMLEO and for making reusable spacecraft viable.

http://msnwllc.com/Papers/Kirtley_MSNW_ … _final.pdf SLIDE SHOW

http://www.nasa.gov/sites/default/files … apture.pdf In-depth Paper

System masses are tiny, less then 1 ton for a system that can capture 60 ton vehicle at Mars in only a weeks time, because the system is electric and able to modulate drag in real-time it should be able to compensate for atmospheric fluctuations (conventional rigid shields have a narrow window to either burn-up or skip off and go hyperbolic) and brake faster and or safer, sufficiently safe that humans as well as cargo can use it.

The TRL is still low and it will need a few demo missions, but if this is on the table it significantly moves the needle in favor of a SEMI-DIRECT architecture over that of a DIRECT. In semi-direct you normally take a large mass penalty in braking the ERV into Mars orbit, the direct approach skips this by doing as it's name suggests and doing direct atmospheric entry. With nearly free MOI the semi-direct style ERV becomes much simpler as it no longer needs heat-shields or most of the propellent it is normally allocated, it just needs to arrive with the return propellent. Conducting Mars EDL from orbital speed rather then transfer orbit speed considerably simplifies the heat-shield necessary on any lander as well yielding yet more savings and opens the potential of multiple surface sorties from an orbital base.

In fact the ERV can start to become a real space-ship that would be re-used. If it is using a sufficiently high ISP propulsion system that it is not forced to drop stages then a complete trip to and from Mars could consist of just two propulsive events and two airo-captures around Mars and Earth respectively. An Ion engine is the most likely system to be able to do this, half the mass estimates for the magneto-shell are electrical systems that would be redundant with the engine and it's power supply so a simple shunting of power between the engine and shell further reduces mass.

The magneto-capture should be sufficiently low stress on the vehicle that deployed solar panels will survive so the vehicle will not undergoing any change in configuration and will be ready to simply spiral out from Mars and return to Earth. This saves both propellent and time compared to the standard flight plan with Ion propulsion which would have the vehicle spend on the order of 100 days spiraling down to a LMO after initially capturing into a high elliptical orbit as the standard Airo-capture is destructive of delicate solar arrays and can't be combined with SEP. To avoid keeping the crew in near deep-space during this spiral the crew lander is expected to separate before capture and to perform a direct entry. Again the magneto-capture would eliminate the separation event and allow all assets to be kept in reserve for rescue or multiple landings. Landing site options are likely to be massively more flexible with a parking in orbit as well.

Last edited by Impaler (2014-12-09 22:55:04)

Void · 2014-12-10 11:18:27

That's rather good by itself.

Apparently the "Mother Ship" is robotic?

The human portion separates off and aerobrakes on it's own in a conventional fashion.

So, since they are two operations that are merged and then separated, and then merged again, Could gravity assist flybys be used to help push the "Mother Ship" on a path to Mars, and the human part join it just after the last flyby of Earth? (It's dangerous I know).

Impaler · 2014-12-10 16:22:32

Huuu? Your throwing out terms like 'mother ship' without defining anything or even telling me where I am traveling from, is it LEO? The closest thing I can figure is that you are talking about a cycler concept, but cyclers don't brake or go into orbit of any planet so none of this would be applicable to them.

The whole point is that with easy capture you don't NEED to separate/merge vehicles upon arrival at a planet. The whole thing should stay together and brake even if you intend to have some portion of the craft detach and land cause your Entry and thermal loads are that much less at the lower orbital velocity.

The scenario I see is an ERV consisting of a habitat and a SEP propulsion section, it is assembled at L2, crew arrives by taxi. ERV departs for Mars, magneto-captures and circularizes down into Low Mars Orbit, crew transfers to a lander that has been pre-positioned in LMO, lands, conducts surface stay, ascends, docks (rinse repeat for multiple landings if desired). Finally crew returns to ERV and the SEP stage pushes them back towards Earth, upon arrival it dose one magneto-capture pass through Earth atmosphere to go into a highly elliptical Earth orbit that takes it close to L2 and the SEP pushes it into capture at L2. Refuel and re-stock the vehicle and your ready to do it all over again.

Void · 2014-12-10 18:17:15

Well I like your ideas just fine. Good stuff.

But you asked me to explain my previous post, so I will try.

Didn't mean to upset you with a response to your presentation that you don't like.

If I understand what you presented,
-A ship from Earth could include the Plasma Aerocapture ship (Mother Ship), and a personed lander.
-Upon arrival to Mars, the Aerocapture would get captured with a high elliptical orbit, and then make several following orbit lowering grazes of the atmosphere, over weeks of time?
-But the personed vehicle would not wait in orbit for that to be completed, but would land on the surface of Mars almost immediately.

To avoid keeping the crew in near deep-space during this spiral the crew lander is expected to separate before capture and to perform a direct entry.

So;

I was wondering if you could save on fuel by using planetary gravity assists, where the Main Robotics ship would be joined by the personed ship at the event of the final gravity assist pass of the Earth.
It would be a modification. I would eat up time, but would also allow more mass to be transferred with less fuel.

Don't get upset though. You seem to have some very important materials here, and so use a little patience and straiten me out if you feel you have time.

Last edited by Void (2014-12-10 19:00:00)

Impaler · 2014-12-10 23:11:16

The sentence you quote is a description of the current limitations, not the new magneto-capture mission profile, it is what were trying to AVOID, the sentence prior to and following it make this clear. Spiraling is what a SEP would currently do, it dose not involve ANY contact with the atmosphere and is FULLY PROPULSIVE maneuver (meaning it costs propellent) which is also very slow on the order of 100 days, both BAD.

All forms of airo-capture even done conventionally with heat-shields are much much faster then that, and the magneto form promises to be even faster as you can do it more aggressively. It's estimated take only about 8 orbits of Mars cause your going in for atmospheric drag ever orbit, it should takes a little under a week so their is no reason to try to drop the lander/s during this time, and thus I don't even PUT the lander/s on the crewed vehicle, I'd deliver them to LMO with another separate ship and just meet them in low orbit once all the ships have achieved circular orbits, this lets us have a crew vehicle and lander that are each optimized for what they need to do and the crewed vehicle can be easily loaded with propellent for the return journey without growing to huge battle-star-galactica size.

Also were talking about a 1 tone device here, it's not a 'Plasma airo-capture ship' it's a comparatively tiny additional device on a ship or stage that already has some function, I recommend a Solar Electric Propulsion stage have this added too it, but again this is not a mother-ship because it dose not come apart or launch things at any time in the mission.

The device can be put on all kinds of stuff, if we wanted to send a lander on direct entry to Mars you could put this device on and capture to LMO first, then initiate a decent with a RCS and make a much milder EDL. As I keep saying you should NEVER do direct entry if you have this tech available, bleeding off HALF or more your total speed is just a no-brainer before taking the final plunge into the atmosphere, heck their may even be uses for the magneto in that plunge too, but that hasn't been studied yet, their is an altitude where the air is too thick to generate a plasma and you would lose all drag.

I still don't understand your gravity-assist question, your still not providing enough of a description of the mission or segment your describing for me to give you a meaningful answer, are you talking about Earth departure or Earth-return, or a return that's attempting to dove-tail into future re-use as I described? What is a 'Robotics ship' a ship full of robots and piloted by the HAL9000? What purpose dose it serve in the mission, we generally name ships with some adverbs that describe what they do and these have became a set of TLA (Three Letter Acronyms) like 'ERV = Earth Return Vehicle' and 'MAV = Mars Assent Vehicle' which have become the standard parlance of talking about Mars missions that are inspired by Mars Direct and they are really helpful in keeping us talking about the right vehicle at the right time cause at some phase of the mission nearly EVERY vehicle involved would be under autonomous and be 'robotic'.

You can't get a gravity-assist unless your already flying heliocentric and whip by a planet stealing some of it's angular momentum around the sun and flying off at high speed, by definition that's a useless maneuver when by goal is to STOP each time I arrive at Earth and Mars so I can't see how gravity assist can EVER be part of a Mars mission. Perhaps you meant plunging towards the Earth from high orbit or from L2 to do a Mars injection burn with Oberth-effect bonus? That is a good strategy but it's not the same kind of free-lunch that gravity-assist/sling-shot is, it just matches the performance of a injection burn done from LEO so your work getting to L2 is not wasted. Many L2 departure scenarios already assume this maneuver if they are chemical and are assembled at L2.

If you were doing something like that their is still no reason to dock during or after rather then before this maneuver. If I have 2 vehicles at L2 and I want to send them off to Mars I would join them at L2 and then do the plunge towards Earth and escape burn with the vehicles connected the whole time. Now I only need 1 engine to ignite rather then two, and I don't have the chance that they fail to dock at a later date (which will happen if either burn is not PERFECT).

Again I think your confusing cycler concepts here which involve manned taxi craft boosted to high speed to rendezvous with larger habitat craft that are just zipping by the Earth already on Mars bound helio-centric trajectories, but these are extremely risky because failure to time the boosts of the manned craft PERFECTLY results in everyone dieing in space when they can't get to the supplies/safety of the cycler.

Last edited by Impaler (2014-12-10 23:17:31)

Void · 2014-12-11 06:48:08

Sure.

Quaoar · 2014-12-29 17:24:22

Impaler wrote:

This novel new idea for capturing into Mars (or other planetary) orbits looks to have huge potential for reducing IMLEO and for making reusable spacecraft viable.
http://msnwllc.com/Papers/Kirtley_MSNW_ … _final.pdf SLIDE SHOW
http://www.nasa.gov/sites/default/files … apture.pdf In-depth Paper
System masses are tiny, less then 1 ton for a system that can capture 60 ton vehicle at Mars in only a weeks time, because the system is electric and able to modulate drag in real-time it should be able to compensate for atmospheric fluctuations (conventional rigid shields have a narrow window to either burn-up or skip off and go hyperbolic) and brake faster and or safer, sufficiently safe that humans as well as cargo can use it.
The TRL is still low and it will need a few demo missions, but if this is on the table it significantly moves the needle in favor of a SEMI-DIRECT architecture over that of a DIRECT. In semi-direct you normally take a large mass penalty in braking the ERV into Mars orbit, the direct approach skips this by doing as it's name suggests and doing direct atmospheric entry. With nearly free MOI the semi-direct style ERV becomes much simpler as it no longer needs heat-shields or most of the propellent it is normally allocated, it just needs to arrive with the return propellent. Conducting Mars EDL from orbital speed rather then transfer orbit speed considerably simplifies the heat-shield necessary on any lander as well yielding yet more savings and opens the potential of multiple surface sorties from an orbital base.
In fact the ERV can start to become a real space-ship that would be re-used. If it is using a sufficiently high ISP propulsion system that it is not forced to drop stages then a complete trip to and from Mars could consist of just two propulsive events and two airo-captures around Mars and Earth respectively. An Ion engine is the most likely system to be able to do this, half the mass estimates for the magneto-shell are electrical systems that would be redundant with the engine and it's power supply so a simple shunting of power between the engine and shell further reduces mass.
The magneto-capture should be sufficiently low stress on the vehicle that deployed solar panels will survive so the vehicle will not undergoing any change in configuration and will be ready to simply spiral out from Mars and return to Earth. This saves both propellent and time compared to the standard flight plan with Ion propulsion which would have the vehicle spend on the order of 100 days spiraling down to a LMO after initially capturing into a high elliptical orbit as the standard Airo-capture is destructive of delicate solar arrays and can't be combined with SEP. To avoid keeping the crew in near deep-space during this spiral the crew lander is expected to separate before capture and to perform a direct entry. Again the magneto-capture would eliminate the separation event and allow all assets to be kept in reserve for rescue or multiple landings. Landing site options are likely to be massively more flexible with a parking in orbit as well.

I'have read about it. If it works, it will cut by an half the deltaV budget of a mars mission, so it will be very easy to build a complete reusable orbit to orbit spaceship (something like GW's design) and perform magnetoarocapture at Mars and Earth arrive. Evan a mission to Saturn with a solid core NTR will be easier with this device: we can use it at Earth return and reuse the whole spaceship.

SpaceNut · 2014-12-29 21:00:35

Huge energy (extra mass for supply, plus structure mass) needed to create a field to hold plasma which is created by placing an element ( of unknown origin ) of some type to make basically an atmospheric air break....
Gravitaional capture would do the same thing, just use a retrograde path to get in front of the target and slow to allow it to be captured orbit.

Impaler · 2014-12-29 22:22:45

Energy costs are very low, masses are 1-2% of entry and far less the heat-shields, read at least the slideshow before you comment.

Gravitational capture is slow and time spent doing it is effectively added to Transit time for radiation/consumables etc, it is likely to be a good interim solution for unmanned cargo and robotic missions though.

Last edited by Impaler (2014-12-29 22:24:27)

Quaoar · 2014-12-30 14:44:52

Impaler wrote:

Energy costs are very low, masses are 1-2% of entry and far less the heat-shields, read at least the slideshow before you comment.
Gravitational capture is slow and time spent doing it is effectively added to Transit time for radiation/consumables etc, it is likely to be a good interim solution for unmanned cargo and robotic missions though.

500 Gauss is only 0.05 Tesla and is not a huge field: probably the whole machine will have a mass of 100-200 kg (Boeing's mini-magnetosphere projected to shield the crew from SEP an CGR during Earth-Mars and Mars-Earth voyage has 0.75 Tesla and a mass of 3000 Kg cryocooler included).

A 100-200 kg magnetoshell weight less than an aerocapture thermal shield and less and less than the huge amount of propellant you save avoiding an all-propulsive insertion maneuver. With this device an Earth-Mars trip and return will have almost 7 km/s of delta-V instead of 14 km/s.
If magnetoshell works, it will be better a chemical propelled spaceship with magnetoshell than a nuclear propelled spaceship without it.

Last edited by Quaoar (2014-12-30 15:15:24)

SpaceNut · 2014-12-30 16:04:50

The paper indicates solar power for energy to create shield but panels can not be deployed when shield power is needed so a larger battery is needed to sustain power through out the aerocapture process.

Also a magnetic guass is different than Tesla since that is Radiant/Radio Frequency energy or RF which is EMF (Electro-magnetic Field) radiation strength. Reading the structure it indicates a Dipole which is RF not magnetic. The plasma is contained via a rotating field which is not RF energy but magnetic.

A magnetic field drops off very rapidly with even small distances and require a ferite core to mantain its strength versus a plain coil of wire.

Think of RF as AC created field while Guass is a DC or permanent magnet field.

Some numbers for field strength:
0.31–0.58 gauss – the Earth's magnetic field at its surface
25 gauss – the Earth's magnetic field in its core
50 gauss – a typical refrigerator magnet
100 gauss – a small iron magnet
2000 gauss – a small neodymium-iron-boron (NIB) magnet

Search and found the old topics which discuss Artificial Magnetosphere - Electromagnetic Induction

Mini magnetosphere radiation shielding for a manned mission

Space Radiation + counter measures

Last edited by SpaceNut (2014-12-30 16:25:37)

SpaceNut · 2014-12-31 23:28:09

I was reminded of what happens to the Earth as well as other atmospheres where the outer reaches of them are plasma... The suns solar winds blow them away....

Solar Wind Workhorse Marks 20 Years of Science Discoveries

At their worst, CMEs can compress the magnetosphere so severely that satellites suddenly find themselves outside that protective bubble, exposed to harsh solar radiation. The compression can also set off vibrations in the magnetosphere that can induce electrical surges in power grids on Earth.
One big mystery is the question of what keeps the solar wind heated. One would think that the solar wind would cool down as it expands and travels away from the sun, but it remains hotter than expected. Some intrinsic activity within the wind must continue to generate heat. It is known that magnetic reconnection - a process in which magnetic energy is converted into heat and acceleration of particles - is part of the process. In sync with this endeavor, Wind has searched for the signatures of magnetic reconnection closer to home.

SpaceNut · 2015-01-01 21:02:38

Earth’s ‘plasmaspheric hiss’ protects against a harmful radiation belt is the result of very low-frequency electromagnetic waves in the Earth’s upper atmosphere that, when played through a speaker, resemble static, or white noise.

This natural, impenetrable barrier appears to be extremely rigid, keeping high-energy electrons from coming no closer than about 2.8 Earth radii – or 11,000 kilometers from the Earth’s surface.

This image shows a colour-coded representation of ultra-relativistic electron fluxes, based on orbital tracks of the Van Allen Probe B spacecraft projected onto the Earth’s equatorial plane. The “spirograph” pattern is formed by the spacecraft’s precessing elliptical orbit. Inside of this radial distance is an almost complete absence of electrons, forming the “slot” region. The superimposed circle shows a sharp, distinctive inner boundary for ultra-relativistic electrons, and how generally symmetric this boundary is around Earth

So how is the plasma held in place?

The team found that no matter where these electrons are circling around the planet’s equator, they can get no further than about 11,000 kilometres (6,800 miles) from the Earth’s surface – despite their intense energy.
Although VLF transmissions can leak into the upper atmosphere, the researchers found that such radio waves would only affect electrons with moderate energy levels, with little or no effect on ultrarelativistic electrons.
Instead, the group found that the natural barrier may be due to a balance between the electrons’ slow, earthward motion, and plasmaspheric hiss. This conclusion was based on the Van Allen probes’ measurement of electrons’ pitch angle – the degree to which an electron’s motion is parallel or perpendicular to the Earth’s magnetic field. The researchers found that plasmaspheric hiss acts slowly to rotate electrons’ paths, causing them to fall, parallel to a magnetic field line, into Earth’s upper atmosphere, where they are likely to collide with neutral atoms and disappear.

SpaceNut · 2015-01-09 21:59:37

Found this description of plasma
http://www.grc.nasa.gov/WWW/ion/overview/overview.htm

Plasma is an electrically neutral gas in which all positive and negative charges—from neutral atoms, negatively charged electrons, and positively charged ions—add up to zero. Plasma exists everywhere in nature; it is designated as the fourth state of matter (the others are solid, liquid, and gas).
It has some of the properties of a gas but is affected by electric and magnetic fields and is a good conductor of electricity. Plasma is the building block for all types of electric propulsion, where electric and/or magnetic fields are used to push on the electrically charged ions and electrons to provide thrust.
Examples of plasmas seen every day are lightning and fluorescent light bulbs.

Quaoar · 2015-01-11 11:54:45

Impaler wrote:

This novel new idea for capturing into Mars (or other planetary) orbits looks to have huge potential for reducing IMLEO and for making reusable spacecraft viable.
http://msnwllc.com/Papers/Kirtley_MSNW_ … _final.pdf SLIDE SHOW
http://www.nasa.gov/sites/default/files … apture.pdf In-depth Paper
System masses are tiny, less then 1 ton for a system that can capture 60 ton vehicle at Mars in only a weeks time, because the system is electric and able to modulate drag in real-time it should be able to compensate for atmospheric fluctuations (conventional rigid shields have a narrow window to either burn-up or skip off and go hyperbolic) and brake faster and or safer, sufficiently safe that humans as well as cargo can use it.
The TRL is still low and it will need a few demo missions, but if this is on the table it significantly moves the needle in favor of a SEMI-DIRECT architecture over that of a DIRECT. In semi-direct you normally take a large mass penalty in braking the ERV into Mars orbit, the direct approach skips this by doing as it's name suggests and doing direct atmospheric entry. With nearly free MOI the semi-direct style ERV becomes much simpler as it no longer needs heat-shields or most of the propellent it is normally allocated, it just needs to arrive with the return propellent. Conducting Mars EDL from orbital speed rather then transfer orbit speed considerably simplifies the heat-shield necessary on any lander as well yielding yet more savings and opens the potential of multiple surface sorties from an orbital base.
In fact the ERV can start to become a real space-ship that would be re-used. If it is using a sufficiently high ISP propulsion system that it is not forced to drop stages then a complete trip to and from Mars could consist of just two propulsive events and two airo-captures around Mars and Earth respectively. An Ion engine is the most likely system to be able to do this, half the mass estimates for the magneto-shell are electrical systems that would be redundant with the engine and it's power supply so a simple shunting of power between the engine and shell further reduces mass.
The magneto-capture should be sufficiently low stress on the vehicle that deployed solar panels will survive so the vehicle will not undergoing any change in configuration and will be ready to simply spiral out from Mars and return to Earth. This saves both propellent and time compared to the standard flight plan with Ion propulsion which would have the vehicle spend on the order of 100 days spiraling down to a LMO after initially capturing into a high elliptical orbit as the standard Airo-capture is destructive of delicate solar arrays and can't be combined with SEP. To avoid keeping the crew in near deep-space during this spiral the crew lander is expected to separate before capture and to perform a direct entry. Again the magneto-capture would eliminate the separation event and allow all assets to be kept in reserve for rescue or multiple landings. Landing site options are likely to be massively more flexible with a parking in orbit as well.

Magnetoshell may also be very useful in a robotic mission to Titan: we can use it to directly capture the spacecraft from hyperbolic entry to Titan orbit, avoiding the risk of passing between the rings, like Cassini did, using the big antenna as a shield against debris.

If we put a magnetoshell on the tail of a manned nuclear spaceship like NTR Copernicus, we will have a huge propellant saving that enable even a manned mission to Callisto.

Last edited by Quaoar (2015-01-11 11:58:06)

Impaler · 2015-01-11 12:38:23

I find anything manned in the outer solar-system very speculative simply due to the duration of life-support and human-factors necessary to get their, it is not a propulsion problem alone, the radiation fields of the gas-giants make the GCR and solar-flares look mild.

That said the ability to brake cheaply at such locations would be great for any mission, Callisto though is not such a location, it's got practically no atmosphere so unless you were planning to brake in Jupiter's upper atmosphere and take a massive radiation dose I don't see the benefits. Titan is a very airo-brakable locations though and an unmanned probe using this tech to get into orbit their would be nice, though the savings may not be so huge because probes can do slow ballistic captures at almost no propellent cost.

Fast and cheap braking looks to be most critical for Mars, Venus, Earth where we have a strong incentive to reduce trip duration due to radiation/life-support concerns, yet we face a double propulsion penalty for doing so, once when we escape Earth and again when we brake. Slow ballistic capture would continue to expose crew to all the radiation of interplanetary space so it just trades propellent mass for radiation protection mass, thus the need for a fast braking with the planets atmosphere.

SpaceNut · 2015-01-12 21:03:44

Public service announcement...

NASA invites community to learn about Magnetospheric Mission

NASA's Goddard Space Flight Center Visitor Center in Greenbelt, Maryland, will host a Sunday Experiment on January 18, from 1 p.m. to 3 p.m. EST. The event is free and open to the public with a focus on elementary school-aged children and their families.

SpaceNut · 2015-01-28 19:11:57

Thanks You both

Quaoar wrote:

kbd512 wrote:
Why is everyone so fixated on using aluminum? Thin aluminum sheeting is good for not only experiencing the direct effects of high energy ionized particles, but secondary effects from interaction between the ions and the atomic structure of the material they're being driven though.
More overwrap required.
Because it's lightweight, robust and cheep. You cannot have a passive shield against GCR even with polyethylene, unless you build a spaceship with two meters thick walls.
What you need is only a solar flare protected zone: a double aluminium wall filled with 20-25 cm of water ice is good. Ice it is also a very good heat sink for waste heat and a protection against meteorite puncture.
For CGR protection it will be better something like Boeing's 1500 kg superconductive mini-magnetosphere
http://arxiv.org/pdf/1406.1159.pdf

As the link is about how to create a megosphere which can be used for protection from radiation and for atmospheric airbreaking....

Quaoar · 2015-01-29 07:02:32

Impaler wrote:

I find anything manned in the outer solar-system very speculative simply due to the duration of life-support and human-factors necessary to get their, it is not a propulsion problem alone, the radiation fields of the gas-giants make the GCR and solar-flares look mild.
That said the ability to brake cheaply at such locations would be great for any mission, Callisto though is not such a location, it's got practically no atmosphere so unless you were planning to brake in Jupiter's upper atmosphere and take a massive radiation dose I don't see the benefits. Titan is a very airo-brakable locations though and an unmanned probe using this tech to get into orbit their would be nice, though the savings may not be so huge because probes can do slow ballistic captures at almost no propellent cost. .

Callisto has very thin atmosphere, but the spaceship can use magnetoshell near Jupiter for hyperbolic capture then circularizing the orbit with rockets near Callisto. The spaceship need a command module shielded with 30-40 cm of water for crossing radiant belts, but probably we can use the same magnetoshell as mini-magnestosphere radiation shield.

SpaceNut · 2016-05-19 21:00:45

Antius wrote:

GW Johnson wrote:
Cosmic rays are a very thin drizzle of really-high energy particulate radiation that peaks in years when the sun is less active, at about 60 REM annual dose. The astronaut max allowable dose is 50 REM annual, based on what they think is a 3% increase in cancer late in life (although I do not trust the statistical models they use with low dose radiation). In active-sun years, the cosmic ray dose is closer to only 24 or 25 REM annual. It would take very little shielding effect to cut 60 to 50 REM annual in a peak year; in an off year it's just not much of a credible threat.
GCR is simply not the threat that some make it out to be.
The real danger is short but intense low-energy particulate radiation from the sun: the solar flare event. The last really big one was in 1972, between two of the Apollo landings on the moon. It would have been fatal within hours to any crew in a plain capsule anywhere outside the Van Allen belts. These events are bursts only hours in duration, but are similar in effects to standing in the fallout from an atomic bomb blast: 100's, 1000's, even 10,000's of REM within hours not years.
That kind of radiation is essentially well-shielded by only 15-20 cm thickness of water (liquid or solid, doesn't matter). If you have life support for people, then you have water and wastewater tanks. If you are doing spin gravity (which enables free-surface water cooking, and allows the use of frozen food), then you will likely have frozen food, which is rich in ice content. You only need a small space surrounded by these things for the crew to shelter for a few hours.
I suggest that the vehicle's flight control station be the shelter, so that any critical maneuvers could still be flown, regardless of the solar weather. It really isn't hard to design this way at all. But current capsule designs do not allow for such arrangements. However, if you are building a real orbit-to-orbit vehicle "from scratch", it is easy to include arrangements like this in the basic design.
Having an asteroid or other body to hide behind just makes the shielding effects on GCR that much more effective. You get that effect while in low Mars orbit, even though Mars has no shielding magnetic field. The planet blocks out (crudely) half the sky.
GW
That is good news. A while back I read an article concerning the use of magnetic fields for radiation shielding of interplantary space craft. It had previously been assumed that huge fields with strengths of 100s of Tesla would be required. These were clearly impractical for small spacecraft and required super-conductors. Recalculation revealed that fields of around 1Tesla were adequate to protect a radius of 100-200m from cosmic radiation. This is within the limits of non-superconducting iron core solenoids. Whilst still relatively heavy, it would be easy to incorporate such items within a static base on Mars, the Moon or Phobos, effectively eliminating one of the big problems of thin or non-existant atmospheres. Something like this would not be difficult to fabricate from local materials.

GW Johnson · 2016-05-20 13:45:09

My assessment of the GCR radiation dangers are valid out to Mars, maybe the asteroid belt. I don't know if there's more of that the further out you go.

The van Allen belts around Earth are quite lethal if you stay in them. That's why we don't talk about men orbiting the Earth above about 900 miles anymore. I think that stuff is similar to solar flare stuff, so the water helps. You don't need it if you transit the region rapidly. That's what Apollo did going to the moon.

The radiation belts around Jupiter are much more intense. I do not know any numbers. Up to a point, 20+ cm of water would help, but if they're strong enough, we may need something better.

Magnetic shielding would be nice. But as I have said elsewhere and elsewhen on these forums, there's usually at least 2 decades between success with a laboratory benchtop experiment, and any sort of practical device we can actually use "in the field". It can be more, if the developers aren't motivated by something more than just profit.

GW

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#1 2014-12-09 22:38:21

Magnetoshell Airocapture

#2 2014-12-10 11:18:27

Re: Magnetoshell Airocapture

#3 2014-12-10 16:22:32

Re: Magnetoshell Airocapture

#4 2014-12-10 18:17:15

Re: Magnetoshell Airocapture

#5 2014-12-10 23:11:16

Re: Magnetoshell Airocapture

#6 2014-12-11 06:48:08

Re: Magnetoshell Airocapture

#7 2014-12-29 17:24:22

Re: Magnetoshell Airocapture

#8 2014-12-29 21:00:35

Re: Magnetoshell Airocapture

#9 2014-12-29 22:22:45

Re: Magnetoshell Airocapture

#10 2014-12-30 14:44:52

Re: Magnetoshell Airocapture

#11 2014-12-30 16:04:50

Re: Magnetoshell Airocapture

#12 2014-12-31 23:28:09

Re: Magnetoshell Airocapture

#13 2015-01-01 21:02:38

Re: Magnetoshell Airocapture

#14 2015-01-09 21:59:37

Re: Magnetoshell Airocapture

#15 2015-01-11 11:54:45

Re: Magnetoshell Airocapture

#16 2015-01-11 12:38:23

Re: Magnetoshell Airocapture

#17 2015-01-12 21:03:44

Re: Magnetoshell Airocapture

#18 2015-01-28 19:11:57

Re: Magnetoshell Airocapture

#19 2015-01-29 07:02:32

Re: Magnetoshell Airocapture

#20 2016-05-19 21:00:45

Re: Magnetoshell Airocapture

#21 2016-05-20 13:45:09

Re: Magnetoshell Airocapture

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