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Martian Explorer Radiation Protection

10/03/2016 12:53 AM

Will the Martian spaceship need an active dipole magnetic field for deflecting solar radiation? Can radiation be contained via magnetic field? If so, what field strength corresponds to what radiation level?

https://www.google.com/patents/US20110049303

http://www.universetoday.com/20671/ion-shield-for-interplanetary-spaceships-now-a-reality/

http://space.stackexchange.com/questions/3772/how-much-power-would-a-spacecrafts-magnetic-shield-require

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#1

Re: Martian explorer radiation protection

10/03/2016 10:09 AM

There is already a lot of knowledge about protection against EMPs (electromagnetic pulses). A lot of military equipment is designed to withstand an EMP event, and the danger of an EMP is similar to the danger from a solar flare. Much of the knowledge has to do with circuit design and shielding at the system level, and the techniques used are relatively lightweight and thus are suitable for aircraft. These would therefore be suitable for spacecraft, and no doubt are already being used in all types of spacecraft.

I imagine that protection against a solar flare would thus use a combination of technologies. A 'mini-magnetosphere' would be designed for the astronaut compartment; the rest of the spacecraft would use more conventional shielding. The energy used would likely come from from fuel cells, allowing most of the field energy to be returned to the cells when the danger has passed.

Frankly, it doesn't seem very smart to send humans to Mars without having established a long-term colony on the Moon. Mars is far away and there are only limited periods of time when a trip can be made there and then return. It is essentially airless, like the Moon, so living there would be no different from living on the Moon, except help is much farther way if you need it. I think a lot more robotic exploration needs to be done first, and robotic assembly of habitats needs to be accomplished on the Moon first.

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#4
In reply to #1

Re: Martian explorer radiation protection

10/03/2016 1:30 PM

Back when I was involved, we always figured that 1/8" of aluminum was sufficient for EMP resistance in Earth orbit.

It may differ on Mars.

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#2

Re: Martian explorer radiation protection

10/03/2016 10:48 AM

Obviously a magnetic field deflection system will not be a requirement for space travel like oxygen, water and food. However, if a solar flare happens to steer a plume of protons at an occupied craft outside of the Van Allen belts then a possible fatal problem might happen. IMHO a magnetic shield is a bad idea and I'll explain why.

First, it is really unlikely such a plume will strike an occupied craft during transit. Auroras on Earth are rare events. The cross sectional area of the Earth is many orders of magnitude larger than any craft with people inside. The Earth's magnetosphere that captures and directs these aurora making plumes is an even larger area. This brings me to my second point.

The magnetosphere concentrates or funnels these plumes to the poles of the Earth. The upper atmosphere ionizes most of these particles to make the spectacular displays we see. Building a magnetic dipole on a spacecraft will deflect the ionized protons from parts of the craft but concentrate them on another. The magnetic bubble will therefore make it more likely to hit the craft, not less.

Lastly, there's the biologic effect from secondary radiation. The average kinetic energy of the protons leaving the sun are so high that it is unlikely that these particles will deposit any of its energy in the low density material that is human flesh. Those particles that do collide with a water molecule or whatever will certainly kill the cell they collide with. The lower energy of secondary radiation after the collision will damage a stream of cells downstream of the collision. My point here is that the secondary radiation effects are more damaging than the primary radiation. The hull of the craft will certainly be denser. The secondary radiation inside the craft from the poles on the craft will need to stop this more lethal secondary radiation. It maybe the safety protocol for a detected incoming proton plume will be a mass EVA outside of the craft.

Fortunately we won't have to guess about what will be the best procedure. We're testing for this scenario.

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#15
In reply to #2

Re: Martian explorer radiation protection

10/04/2016 6:15 AM

My understanding is that high energy particles are trapped in the Van Allen belts, not typically dumped to the poles. The concentration of energetic protons and electrons in the belts presents a hazard to electronics or living organisms transiting the belts.

.

As for shielding a trip Mars, it shouldn't be too difficult to arrange a magnetic shield that stays between the ship and the Sun and collects high energy particles on small charged plates (well shielded for Compton scattering, Bremsstrahlung, etc).

.

While secondary effects may be significant, you don't escape secondary effects by refusing to shield an initial high energy flux.

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#3

Re: Martian explorer radiation protection

10/03/2016 12:18 PM

Given the prediction capabilities, the time it takes to get to Mars, and the rarity of such events, it seems IMHO that protection against those events should center around any colony established. Any colonists will be there for a long time, making the probability of encountering a solar flare approach 100%.

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#5

Re: Martian Explorer Radiation Protection

10/03/2016 3:23 PM

Well is light bent around planetary bodies by space-time or the magnetosphere, or both?...How can you tell the difference? Which is a more powerful bending force? Are there certain frequencies of radiation more influenced than others?

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#6
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Re: Martian Explorer Radiation Protection

10/03/2016 3:35 PM

Light beams are not bent by magnetic fields. Charged particle beams are bent by magnetic fields.

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#7
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Re: Martian Explorer Radiation Protection

10/03/2016 4:17 PM

But isn't light both wave and particle...?

..."the path light takes is not affected by the presence of a magnetic field. Light itself is composed of an oscillating electric and magnetic field, and one very important property of electric and magnetic fields is what we call "linearity." That is, if you have two sources of electric and/or magnetic fields, you can predict what the combined field is just by adding the two source fields together. The two fields don’t change each other at all. So if you add the field of a light ray to any other field we can imagine, the light ray will continue as before and the extra field will just stay the same, adding to it in places where the extra field is strong, but having no effect beyond the reach of the extra field. So there is no way that a magnetic field can bend light. "...

https://light2015blog.org/2015/04/09/are-light-and-charged-particle-beams-two-sides-of-a-same-coin/

http://van.physics.illinois.edu/QA/listing.php?id=2009

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#8
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Re: Martian Explorer Radiation Protection

10/03/2016 4:28 PM

Photons have no charge!

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#9
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Re: Martian Explorer Radiation Protection

10/03/2016 5:05 PM

If photons have no charge, how is electricity created from solar cells...?

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#10
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Re: Martian Explorer Radiation Protection

10/03/2016 5:44 PM

Photovoltaic (PV) panels convert the sun's rays into electricity by exciting electrons in silicon cells using the photons of light from the sun. Then there's all this stuff about silicon and loose electrons being knocked about and causing a charge of electricity to flow. Well, you know, it just does.

Besides, if photons had an electrical charge, wouldn't we get electrocuted when we went outdoors?

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#11
In reply to #10

Re: Martian Explorer Radiation Protection

10/03/2016 6:20 PM

Isn't sunburn the result of charged particle energy...?

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#12
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Re: Martian Explorer Radiation Protection

10/03/2016 6:38 PM

No. Sunburn is the result of stupidity.

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#13
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Re: Martian Explorer Radiation Protection

10/03/2016 8:42 PM

Photons knock electrons loose in the silicon diode junction and the electric field in the depletion zone accelerates them to one of the electrodes.

"Theory[edit]

Working mechanism of a solar cell Main article: Theory of solar cells

The solar cell works in several steps:

  • Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon.
  • Electrons are excited from their current molecular/atomic orbital. Once excited an electron can either dissipate the energy as heat and return to its orbital or travel through the cell until it reaches an electrode. Current flows through the material to cancel the potential and this electricity is captured. The chemical bonds of the material are vital for this process to work, and usually silicon is used in two layers, one layer being bonded with boron, the other phosphorus. These layers have different chemical electric charges and subsequently both drive and direct the current of electrons.[2]
  • An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity.
  • An inverter can convert the power to alternating current (AC).

The most commonly known solar cell is configured as a large-area p–n junction made from silicon."

https://en.wikipedia.org/wiki/Solar_cell

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#14
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Re: Martian Explorer Radiation Protection

10/04/2016 5:39 AM

Your intuition was right, even some of your reasoning was a bit spurious...

Light can bent or turned, in a sense, by magnetic fields, as in the Faraday effect, wherein circular polarization can be turned from from right to left (or vise versa) or linear polarisation can be rotated.

Similarly, a magnetic field can be created by a laser pulse.

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#16

Re: Martian Explorer Radiation Protection

10/05/2016 1:54 PM

It seems that a logical order for space travel would be: first an animal, then a man in orbit, then a trip to the moon and back, then a space station, then a moon colony, then a robot to Mars, then an animal to Mars, then a man in orbit around Mars, then a trip to Mars and back, then a colony on mars, etc,etc,etc.

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#17
In reply to #16

Re: Martian Explorer Radiation Protection

10/05/2016 3:08 PM

'...then an animal to Mars, then a man in orbit around Mars, then a trip to Mars and back, then a colony on mars...'

.

The suggested diminutive incremental steps are excessively cautious and add monumental additional costs without improving chance of success greatly.

Homo sapien sapiens are of kingdom Anamalia, so there is no need to double the cost by devoting an entire voyage to some species that arguably doesn't approve of the plan, and wouldn't be going voluntarily.

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Also, the 'send someone to orbit Mars' and 'send someone to land on Mars ad retur' should also be consolidated. We already have robots there. What critical info do you expect to glean merely having the addition of a pair of human eyes in orbit?

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Exploring and pioneering involve inherent risks, a land whole those risks should be minimized as much as s reasonably possible, we seem to have lost track of reason in some aspects. Fear has paralyzed our development 9f the solar system, making systems more expensive multiple times over and pushing back milestones by decades.

I suspect that many older astronauts would jump at the chance to join pioneering missions that rapidly advance our plans to colonize the Moon and Mars at the cost of some additional risk.

.

This situation has parallels to current problems associated with end of life medical care. The family of the patient doesn't want to put a price on their loved ones life, but if the patient has their wits about them they may understand that extending their bed ridden existence for another month by utilizing a new procedure that costs as much as a modest starter home, isn't doing anyone any favors.

.

People are not an endangered species....what were you going to send, a chimp? Those are endangered, IIRC. Better to alow someone to volunteer for a trip with a stated, conservatively estimated mortality and morbidity risk of say 40%, and be a hero, than make the program tens times more expensive and 3 decades late....only to have a chimp get there first.

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#18
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Re: Martian Explorer Radiation Protection

10/05/2016 4:11 PM

First I would like to congratulate you for getting a, score 1 for good answer, by commenting how diminutive my comment to this blog was.

I suppose we humans could continue to pursue the folly of using cast iron rivets on the Titanic or not checking to see if cold weather will make o rings on the challenger leak.

From what I understand, the space station was designed with the intention that human beings could learn to live and work in outer space, unless all of that time and decades spent was just a waste of time and resources.

When you speak of " fear ", you sound like that airport commando in in the terminal asking Tom if he is afraid of ghost's.

There are plenty of warm bodied homo sapiens out there to strap in a rocket seat and if they perish, then Ed Mc Mahon can just call out " come on down ! " Your the next contestant on stupid is as stupid does.

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#21
In reply to #18

Re: Martian Explorer Radiation Protection

10/06/2016 2:24 AM

No, you've got my opinion of your comment all wrong. I appreciate your comment. It is the opposite of diminutive. It represents the widely accepted outlook/ ingrained standard approach.

I apologize if it felt as though I was attacking you personally. You aren't responsible for the standard and I fully support your right to express any opinion you have about the standard or any proposed alternatives.

You and your comments are just fine. What does deserve reevaluation is the unbridled expendature of time and money trying to keep risks exceedingly low.

Think about how waiting until technology could reduce risks to an absolute minimum would have retarded both exploration and technology itself historically. Christopher Columbus would probably have died in Europe at a ripe old age in his bed, never having crossed the Atlantic..so safe. Yet, so much less for that safety, and still dead by this date, either way.

No one is forcing you or anyone to be exposed to additional risks or to be a pioneer. Countless highly qualified people would likely be willing to accept significant risks to rapidly advance the colonization of the Moon and Mars. Danger is part of the exhilaration of exploration/adventure and it has far greater appeal to many than the increased chance of dying a peaceful death of old age in your home town, brought about by never having risked significant venture.

As a society we are obsessed with the ultimate safety of 'the public'. Individuals willingly engage in additional serious risks for sometimes frivolous gains, yet as a society, we add enormous burdens of cost and delays in progress chasing risk minimization.

It really isn't acceptable to work on the basis of reducing risk at any cost. As mentioned before, the problem os quite similar to the problem of excessive medical costs for end of life care.

We really should be putting a cap on the amount we are willing to spend for an additional day of an individuals life. This deserves discussion at many levels.

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#22
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Re: Martian Explorer Radiation Protection

10/06/2016 2:39 PM

I see I will need to respond, paragraph by paragraph.

A. This one made me chuckle, first I read that you respect my opinion, then you say I have an " ingrained " approach.

B. I didn't know that there was a standard for doing something safe.

C. Generally the idea of keeping risks low, especially in outer space, is that there is no instant replay, you make a boo-boo and the results are terminal.

D. From what I understand, the Vikings made the trip across the pond many moons before Columbus did, and they did it with the technology available to them, so by the time Christopher did it a lot of the bugs were ironed out.

E. Funny thing about all of them type A risk takers, when the $hit hits the fan, they are all crying for their momma, just like the weakest of the rest of us.

F. Personally I like the fact that numerous test dummies gave their all just so I could have a better seat belt in my car.

G. I would really like to hear that astronauts response when mission control tells him because of budget constraints, they decided against giving him a " spare " space suit.

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#23
In reply to #22

Re: Martian Explorer Radiation Protection

10/06/2016 3:22 PM

Few things are inherently safe. Apollo 1 blew up on the ground.

You are right about low risks, but risk must be balanced against cost.

Who knows how many Viking ships vanished before that first one returned.

From my seat, I'm not sure that there is a real need to send humans to Mars, now or ever. We have so many unsolved problems here on our planet that we could spend years and years improving how people live here without ever knowing how it is to live on Mars.

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#24
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Re: Martian Explorer Radiation Protection

10/06/2016 3:36 PM

Well the idea about going and settling mars is that the rich can start living on an unpolluted planet and leaving this worn out used up planet for the rest of us.

A whole squad of engineers will help them do it, and when the job is done, they will just flush most of them like yesterday's refuse.

This will happen just before all of the natural resources are all used up.

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#25
In reply to #24

Re: Martian Explorer Radiation Protection

10/06/2016 4:02 PM

Yellowstone will erupt and kill us all before any of that happens.

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#27
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Re: Martian Explorer Radiation Protection

10/06/2016 10:26 PM

Lyn, you watch too many apocalyptic movies !

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#29
In reply to #24

Re: Martian Explorer Radiation Protection

10/07/2016 1:26 AM

It.would be far easier, cheaper, safer, etc, to simply build a structure to wall off the polluted Earth, here on Earth, that build a similar structure on Mars.

.

I think the benefit of populating Mars would be the species might survive if Yellowstone erupts or another like the Dino-killing asteroid strikes.

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#28
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Re: Martian Explorer Radiation Protection

10/07/2016 1:21 AM

A. I said 'appreciate'. Is the some exclusion of appreciation from anything ingrained in your perspective?

B. 'Safe' is not go/no-go condition. It is a scale. You aren't really considering what I am suggesting if you insist on portraying the current system as 'safe' and anything else as not.

C. I don't have anything against keeping risks low, within reason.

D. Yeah, I shoul. have picked another adventurer. Amelia Earhart?

E. Hmm. There are examples to the contrary.

F. Yes, but note, test dummies are not taking every first drive to the grocery store. Neither is a chimp.

G. I'm beginning to suspect you actually realize I have a point. Otherwise you wouldn't feel the need to distort the argument to the point of absurdity to argue against it.

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#26
In reply to #21

Re: Martian Explorer Radiation Protection

10/06/2016 9:34 PM

I still think it will be far better to first make a permanent manned scientific post on the moon, (like McMurdo station) before anyone commits to transporting people outside of our solar orbit.

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#20
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Re: Martian Explorer Radiation Protection

10/05/2016 4:56 PM

It's not as easy as going to the moon:

How long would a trip to Mars take?

Just like you have to wait for Earth and Mars to be in the proper position before you head to Mars, you also have to make sure that they are in the proper position before you head home. That means you will have to spend 3-4 months at Mars before you can begin your return trip. All in all, your trip to Mars would take about 21 months: 9 months to get there, 3 months there, and 9 months to get back. With our current rocket technology, there is no way around this. The long duration of trip has several implications.

In the nine months it takes to get to Mars, Mars moves a considerable distance around in its orbit, about 3/8 of the way around the Sun. You have to plan ahead to make sure that by the time you reach the distance of Mar's orbit, that Mars is where you need it to be! Practically, this means that you can only begin your trip when Earth and Mars are properly lined up. This only happens every 26 months. That is there is only one launch window every 26 months.

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#19

Re: Martian Explorer Radiation Protection

10/05/2016 4:49 PM

Last I heard, the planet Mars wasn't deviating much from it's orbit these days, so it seems reasonable that it will be around awhile longer, and thus, to ask:

''Why are we not first planning a ''pilot'' colony on Earth's Moon to (robotically?) mine it, take long-term measurements (of radiation levels, etc.), and develop an operating prototype of a human-habitable habitat, as a preparitory-mission before going all the way out to Mars???

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