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#76 2022-08-10 18:28:33

tahanson43206
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Registered: 2018-04-27
Posts: 18,142

Re: Large Ship Radiation Protection

Here's a report on research about galactic cosmic rays ...

https://www.nasa.gov/feature/goddard/20 … -particles

Fermi has shown that the shock waves of exploded stars boost particles to speeds comparable to that of light. Called cosmic rays, these particles mostly take the form of protons, but can include atomic nuclei and electrons. Because they all carry an electric charge, their paths become scrambled as they whisk through our galaxy’s magnetic field. Since we can no longer tell which direction they originated from, this masks their birthplace. But when these particles collide with interstellar gas near the supernova remnant, they produce a tell-tale glow in gamma rays – the highest-energy light there is.

“Theorists think the highest-energy cosmic ray protons in the Milky Way reach a million billion electron volts, or PeV energies,” said Ke Fang, an assistant professor of physics at the University of Wisconsin, Madison. “The precise nature of their sources, which we call PeVatrons, has been difficult to pin down.”

Trapped by chaotic magnetic fields, the particles repeatedly cross the supernova’s shock wave, gaining speed and energy with each passage. Eventually, the remnant can no longer hold them, and they zip off into interstellar space.

Boosted to some 10 times the energy mustered by the world’s most powerful particle accelerator, the Large Hadron Collider, PeV protons are on the cusp of escaping our galaxy altogether.

Astronomers have identified a few suspected PeVatrons, including one at the center of our galaxy. Naturally, supernova remnants top the list of candidates. Yet out of about 300 known remnants, only a few have been found to emit gamma rays with sufficiently high energies.

One particular star wreck has commanded a lot of attention from gamma-ray astronomers. Called G106.3+2.7, it’s a comet-shaped cloud located about 2,600 light-years away in the constellation Cepheus. A bright pulsar caps the northern end of the supernova remnant, and astronomers think both objects formed in the same explosion.

(th)

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#77 2022-08-10 19:20:03

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,310

Re: Large Ship Radiation Protection

A capacitor that is constructed of an air gap between 2 plates is a transient suppressing design of which the gap is a dielectric that gives it the value it would have to do so. Since the charge is held in place by electrical connections of a plus value connect to one side of the 2 plates while the negative connection is made to the other. Plates that are parallel to the ship's hull total build like an exterior hull. Hence this is for DC use.

A voltage higher than the total dc value if given to the side that would be struct with from the suns solar winds would arc through the void of space in between the plates. The issue for a large ship is that there is no ground return for the charge to pass to and would continue to enter the ships electrical systems.

The only design for I can think of is for plates arrange 90' to the hull perpendicular in which every other plate is connected together to form alternating potentials for it to absorb the particles of energy. Particles are going to pass through these plates due to speed creating more. So, the plates need to be quite large and at a good distance from the hull.

Not to mention you just added more mass to the build flights and then for the exit from orbit which is already not practical fuel requirement

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#78 2022-08-10 20:32:24

tahanson43206
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Posts: 18,142

Re: Large Ship Radiation Protection

For SpaceNut re #77

Thank you for taking up the Radiation Protection question, and for your several interesting and challenging points. 

This is a first reply to let you know the post was viewed.

(th)

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#79 2022-08-10 21:19:29

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
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Re: Large Ship Radiation Protection

tahanson43206 wrote:

For RobertDyck .... the use of a magnetic field is certainly well worth considering, but at this point, to the best of my knowledge (limited as that is) no entity of any kind is using such a system, or even planning experiments to show it would actually work in space.

We are in the Large Ship Radiation Protection topic, so any discoveries a member might make of ongoing research or even speculation are welcome.

PDF directly from University of Washington
Radiation shielding produced by mini-magnetospheres

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#80 2022-08-11 20:23:26

SpaceNut
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Posts: 29,310

Re: Large Ship Radiation Protection

The reason we have not built these devices to give shielding to a crew is energy levels required to power them and we have not stayed beyond the magnetic fields of earth in which then they would be required.

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#81 2022-08-11 20:37:51

tahanson43206
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Re: Large Ship Radiation Protection

As a follow up to the post by RobertDyck ...

here is the closing paragraph from the paper cited:

Further work needs to look at the final solution after multiple pulses to provide that the desired level
of magnetic field of 1 Tm can be achieved along the bulk of the mini-magnetosphere. This paper only
considers two pulses, but the evidence suggests a continued building of the magnetic field. As such there
is potential for providing GeV particle shielding through mini-magnetospheres. This shielding will
required about 100 kW continuous power to support the mini-magnetosphere.

An electrostatic shield system would also require power to replenish the fields as they decay due to arrival of particles, charged or otherwise.

If anyone has time to read the paper more slowly, please try to discover how large the vehicle might be that would be protected by this system.  The paper talks about plasma going out some distance, but that plasma would have to be constantly in motion along the magnetic field lines.  Interesting physics problem, without a doubt.

***
For SpaceNut .... Apollo was outside the magnetic field of the Earth, but the planners took the risk because of competition with the Soviet Union.  Future flights do not have that competitive driver, so it seems to me reasonable to expect better performance from our leaders.

(th)

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#82 2022-08-11 20:45:18

SpaceNut
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Posts: 29,310

Re: Large Ship Radiation Protection

The fields from this energy projected outward at distance from the ship from the mini-magnetospheres...

The capacitive is dead measured on the ship and will enter the ship.

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#83 2022-08-12 03:21:24

RobertDyck
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From: Winnipeg, Canada
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Re: Large Ship Radiation Protection

If a mini-magnetosphere deflects GeV cosmic radiation (aka galactic cosmic radiation) by 0.00229° at a range of 1,000km then that would deflect radiation by 40 metres. The ring of our big ship will have a radius of 37+ metres, so creating a "hole" in the radiation with radius 40 metres will mean the ship is completely protected. The shape of the mini-magnetosphere will not be a sphere, it will be apple shaped with depressions at the poles. That could result in the "hole" in the radiation being a torus, not a sphere. So with the poles of the magnetic field oriented perfect with the axis of rotation of the ship, that means the radiation protected zone is a torus that completely contains the ring of the ship.

I chose 1,000km radius because the paper I linked used. The paper speculates the diameter of the mini-magnetosphere. With a power level of 100kW, would the radius be 300km or 1,000km? The author of the paper doesn't know. We don't know the exact angle of deflection, and we don't know the radius of the "hole" in radiation. But you can see how this works.

We can do a simple test, but it will have to be tested. Mars Direct was developed in the last quarter of 1989 and the first half of 1990, paper presented at a NASA symposium in June 1990. Mars Direct was designed to use an SP-100 nuclear reactor for the Earth Return Vehicle (ERV). SP-100 was under development at that time by the military, as part of Strategic Defence Initiative (SDI) know to the media as "Star Wars". Development of SP-100 was completed in 1992. Some details of the Mars Direct ERV had to be updated when spec's for SP-100 were finalized. SP-100 produced exactly 100kW of electricity, designed to operate in space. Since then the exact same team of engineers have developed SAFE-400, completed in 2007. SAFE-400 also generated 100kW of electricity, and also designed to operate in space. But SAFE-400 is newer, lower total mass, and less fissile material.

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#84 2022-08-12 06:48:25

tahanson43206
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Re: Large Ship Radiation Protection

For RobertDyck re #83

SearchTerm:magnetic radiation protection - summary of capability and power requirement
SearchTerm:nuclear power supply proposed for radiation protection of Large Ship

For SpaceNut or Mars_B4_Moon ... if you find (or run across) information about the reactors mentioned by RobertDyck in post #83, please post link(s) or snippets to show what they are and current status.

Mass requirements for each design, and fuel specification would be helpful as well.

It seems likely (to me at least) that a small compact reactor will require supervision by an agency of a government.

That government would necessarily be a partner (and not a silent partner) in the Large Ship enterprise.

(th)

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#85 2022-08-12 18:04:52

SpaceNut
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Posts: 29,310

Re: Large Ship Radiation Protection

Those reactors are from an ancient time period and the information is available on the web for these. They are not safe for humans to be around when in use due to required level of shielding which makes the large ship even heavier.
The goal is to minimize mass....

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#86 2022-08-12 20:39:25

tahanson43206
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Re: Large Ship Radiation Protection

For SpaceNut re #85

The nuclear age began in 1942.

The use of the word "ancient" is intriguing in that context.

If the designs were solid (and I have no way of knowing, but depend upon others to pass judgement) then they would be as good today as they were when they were approved for use (assuming they ** were ** approved for use).

RobertDyck has been advocating a radiation shield to protect passengers travelling in Large Ship.  The amount of power required to operate the kind of shield he's been proposing is matched by one of the designs you've described as "ancient".

Is there a reason why humans need to be anywhere near a reactor that is powering the radiation shield?  Could RobertDyck arrange things so that the reactor is away from people? 

Hopefully RobertDyck will be willing (and able) to help to clarify the situation.

(th)

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#87 2022-08-13 01:01:23

RobertDyck
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From: Winnipeg, Canada
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Re: Large Ship Radiation Protection

I'm sorry so many people have such difficulty following a simple discussion. I described the Large Ship powered by solar panels. But the solar panels for the Large Ship are huge. To test a mini-magnetosphere, an unmanned probe must be built to prove it works. And to test exactly how far the plasma extends, how much it deflects solar radiation and cosmic radiation, whether it does form a void with zero radiation, what the size an shape of that void is.  An SAFE-400 reactor is perfectly safe for an unmanned test article. It can produce this mini-magnetosphere.

Ps. 2007 is *NOT* "ancient".

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#88 2022-08-13 06:22:46

tahanson43206
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Re: Large Ship Radiation Protection

For RobertDyck re #87

Thanks for your assistance with refresh of our collective memory.

As a side note, but related to your observation about the difficulty of following a conversation ... The Large Ship "conversation" covers two Earth years.  It has covered a wide range of subtopics, and it contains erroneous information as well as correct information. Individual members have multiple topics to try to follow, in addition to yours.  On top of that, individual members have multiple supplies of information coming in from non-forum sources, including television, Internet, hard copy publications (though less of those in recent times) and non-forum conversations. 

You are asking a LOT of members for them to remember everything you have said over two years.

That is why your restatement of your concept of drawing power for the Large Ship from solar panels is worth repeating.

My guess is that if you ever get to the point of working with a ** real ** design team, you'll quickly discover that the challenges of outfitting Large Ship with solar panels to meet all it's needs for a two (Earth year) round trip from Earth to Mars and back will exhaust even your patience, so that addition of a nuclear reactor for baseline power will be a welcome addition to the mix.

The mass required for all those solar panels, the frames to mount them, and the cables and electronics to support them, PLUS the absolutely essential battery storage system to handle periods when sunlight is NOT available will compete with other elements of your 5000 ton mass budget.

On the ** other ** hand, a nuclear reactor will need thermal radiators to manage the dumb heat it generates, and to provide a way to generate electricity from that dumb heat due to the flow of thermal energy from hot to cold.

Hopefully fusion reactors will arrive on the scene to help out by the time your vessel is ready to leave Earth on it's first Solar System outing.  That shakedown cruise would (most likely) be a run out to the Moon and back.

(th)

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#89 2022-08-13 08:35:17

RobertDyck
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From: Winnipeg, Canada
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Re: Large Ship Radiation Protection

I have considered that. I envision a nuclear reactor placed on the engine end of the propulsion module, to keep it as far away from passengers and crew as possible. But I'm still hoping that won't be necessary. Also remember that I want the entire propulsion module to be replaceable as a stage. So it can be replaced when new technology arrives.

Using sunlight directly for oxygen generation will greatly reduce power requirements. And of course we now have LED lights.

Batteries will be necessary, but not as critical as you might think. Remember that in space, sun shines 24/7. There are no clouds, and there's no night. ISS is in Low Earth Orbit. It orbits every 90 minutes, but is only in Earth's shadow about 30% of each orbit. When the Large Ship orbits Mars, it will be in highly elliptical, high Mars orbit. That requires minimum change in velocity (ΔV) when entering Mars orbit, and equally minimum change of velocity when departing to return to Earth. High orbit cuts the time in planetary shadow even further. During transit, the ship won't be close to any planet, so no shadow at all.

I'm thinking a shakedown would involve several incremental steps. Apollo 4 was the first test flight of Saturn V, but it launched a CSM into high Earth orbit, then returned to Earth. Apogee was 18,092 km, although perigee was only ~204 km. I'm thinking the Large Ship should do something like that, and return to LEO. Shakedown around the Moon before proceeding to Mars? Good idea.

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#90 2022-08-13 15:26:11

SpaceNut
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From: New Hampshire
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Posts: 29,310

Re: Large Ship Radiation Protection

Sure a working model...
SP-100 started in 1983 by NASA and revisited Mar 12, 1992 · GAO discussed the SP-100 Space Nuclear Reactor Program

SAFE-400 nuclear reactor seems to have been started before Jan 01, 2002, which is an acronym for Safe Affordable Fission Engine, is a 400-kWt

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#91 2022-08-13 15:56:40

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,852
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Re: Large Ship Radiation Protection

Development of SP-100 was completed on the date you specified in 1992. Dr Zubrin and his partner David Baker included it in their design for Mars Direct. SP-100 was designed to produce 100kWe in 1990, they assumed reducing power to 85kWe would reduce mass. When it was finished in 1992, they discovered total mass would remain exactly the same, so may as well use all 100kWe. Development of SAFE-400 was completed in 2007. It also produces 100kWe. However, to do that SP-100 requires 2000kWt while SAFE-400 only requires 400kWt. It can do this with a more efficient power converter. That converter requires higher operating temperature, so newer materials were required. SAFE-400 has a heavier power converter and radiator assembly, but a core that only produces 400kWt is much smaller/lighter, so overall mass is lower.

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#92 2022-08-13 17:15:22

tahanson43206
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Posts: 18,142

Re: Large Ship Radiation Protection

For RobertDyck re upcoming Zoom...

If (by any chance) you are thinking of participating in the Zoom  tomorrow, I'm trying to coordinate with everyone to use the set of meeting numbers published in Post #1 of the Zoom topic.

When we (kbd512 and I) were given the keys to the Professional Zoom, we were offered assistance if we had any questions.  I didn't know enough to know what question to ask, so didn't ask any.

kbd512 and I have (sort of) managed to use the system, but we made a discovery that is a concern.  Zoom has the capability of setting up multiple repeating sessions, for multiple audiences on different dates.

We have accidentally created multiple sets of numbers for meetings.

I'd like to (try at least to) keep a single set of numbers for all meetings.

The set of numbers I'm hoping we can use over and over again, is published in Post #1 of the Zoom topic.

The correct way for one of us (kbd512 or me) to open a meeting is to start AS A REGULAR MEMBER, and open the Zoom session using the Post #1 numbers.

After the host has connected to the Zoom using the Post #1 numbers, THEN the host can log in using the Mars Society email and special Zoom password.

The result of following this procedure is that we will always be using the same set of numbers.

There is no need (right now) for more than one set of numbers.

You can help (if you are planning to attend tomorrow night's Zoom) by locating the Post #1 numbers and using them to connect.  You should receive a message that the host will admit you shortly (or words to that effect).

(th)

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#93 2022-09-07 06:16:04

Mars_B4_Moon
Member
Registered: 2006-03-23
Posts: 9,774

Re: Large Ship Radiation Protection

This article might be of interest

'What’s Being Done to Protect Astronauts From Radiation in Deep Space?'

https://www.universetoday.com/157458/wh … eep-space/

Solar storms can range from mild outbursts to significant solar energetic particle events, which can be lethal to humans in space. They happen as proton-laden material bursts out from the Sun, generally associated with big solar flares and coronal mass ejections (CMEs). The particles get accelerated by the flares and CMEs and that’s what makes them so deadly. For astronauts in space, the best protection is to be behind protective walls in their capsules and habitats. But, if it turns out that people on a mission are exposed to radiation, medical procedures to help astronauts recover are important to have.

It’s worth remembering that there has been at least one “close call” with lunar explorers and potential solar activity. In 1972, solar storms blasted out past Earth and the Moon. They disrupted satellite communications as well as ground-based communications systems on Earth. Luckily, no Apollo missions were impacted, although the storms occurred between the Apollo 16 and 17 missions. Had they burst out during those missions, things would have gone badly for the astronauts, who would have been sitting ducks either on their way to the Moon or while on the surface.

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