Large Ship Radiation Protection

tahanson43206 · 2022-02-25 10:46:22

Large Ship Prime is: Large scale colonization ship by RobertDyck

This topic is offered to collect knowledge, insights and best practices for a dynamic radiation protection system for Large Ship.

Update 2022/04/03 .... thanks to kbd512 for pointing out an oversight in wording of this topic:

This topic is intended to provide support for ANY version of "large Ship" that comes along. That specifically includes the interesting Counter-rotating design in development by kbd512.

"Large Ship" is (arbitrarily) defined as 5,000 metric tons, for the purposes of calculations to be posted in this topic.

The "traditional" radiation protection system consists of mass that is chosen to dissipate the energy of arriving ions.

Because Large Ship is a space vessel and not a permanent habitat, all mass must contribute to the mission.

A great deal of work on radiation protection has already been done by NewMars members in other topics.

This new topic is intended to provide a drop off point for future posts that will have a direct impact on solving the radiation problem for Large Ship.

Quaoar has recently offered a suggestion for a dynamic radiation protection design that may be able to fend off some of the deep space Cosmic ions that are arriving from every direction. The design described by Quaoar includes a 20 Tesla field and an inner coil to keep magnetic flux away from passengers.

A workable design must (of course) be designed to match the physical layout of Large Ship.

(th)

tahanson43206 · 2022-02-25 12:18:56

This second post in the dedicated Large Ship Radiation Protection topic is intended to remind contributors that there are two available forces ...

High energy ions can be deflected by electrostatic fields as well as magnetic ones.

The use of electrostatic fields for this purpose was discussed in the 1970's and no doubt before.

There are posts in the NewMars archive with details of publications where possible solutions were offered.

This topic is available for refreshing our collective memories of that earlier work, and reporting on new approaches.

The problem is not going away, and customers are going to vote with their feet if they are offered a passenger service to Mars that includes Earth surface equivalent radiation protection, compared to all the competitors who don't.

The fact that Large Ship is shaping up as able to offer other amenities should put it in a class by itself, but we can be sure there will be cut rate, fly by night outfits that will try to secure some business without taking any risks themselves.

Update: a search for electrostatic related to radiation protection revealed this item:
http://newmars.com/forums/viewtopic.php … 64#p175064

(th)

Quaoar · 2022-02-25 15:40:38

tahanson43206 wrote:

This second post in the dedicated Large Ship Radiation Protection topic is intended to remind contributors that there are two available forces ...
High energy ions can be deflected by electrostatic fields as well as magnetic ones.
The use of electrostatic fields for this purpose was discussed in the 1970's and no doubt before.
There are posts in the NewMars archive with details of publications where possible solutions were offered.
This topic is available for refreshing our collective memories of that earlier work, and reporting on new approaches.
The problem is not going away, and customers are going to vote with their feet if they are offered a passenger service to Mars that includes Earth surface equivalent radiation protection, compared to all the competitors who don't.
The fact that Large Ship is shaping up as able to offer other amenities should put it in a class by itself, but we can be sure there will be cut rate, fly by night outfits that will try to secure some business without taking any risks themselves.
Update: a search for electrostatic related to radiation protection revealed this item:
http://newmars.com/forums/viewtopic.php … 64#p175064
(th)

Firstly we have to choose the propulsion system of our big spaceship: if she has some kind of fission gas core NTR, she has to be quite long and narrow, to keep crew and passengers far from core neutron and gamma radiation and to minimize the shadow shield mass. In this case, artificial gravity can be obtained by spinning the ship on the yaw axis - like GW's rigid baton study - and the main superconductive coil can be put in the middle of the ship, with a secondary coil within the bow habitat to locally cancel the field.

If she is some kind of nuclear pulse propulsion, i.e. orion drive, she has to be more compact: in this case the habitats has to be cylindrical: something like the radii of an umbrella, that are kept parallel to the axis during propulsion and opened perpendicular during coasting, while the ship rotates on her roll axis. In this case the main coil has to surround the propulsion axis while the secondary coils have to follow the longitudinal section of the habitats.

Last edited by Quaoar (2022-02-25 15:51:50)

tahanson43206 · 2022-02-25 17:41:24

For Quaoar re #3

Thank you for continuing to contribute important suggestions for Radiation protection!

Please take the time to read the entire topic by RobertDyck (Large Ship Prime)

It is not helpful for contributors to ** this ** topic to offer suggestions that have NOTHING to do with ** this ** topic.

We do need helpful guidance for RobertDyck to help him design his vessel to be safe for passengers and crew.

Offering suggestions that have nothing to do with Large Ship is not helpful. It requires RobertDyck to have to deal with the distraction.

We are two years into development of Large Ship. It is long past time for alternative suggestions.

With that suggestion out of the way, your recommendation for placement of atomic propulsion systems ** can ** apply to Large Ship. All you have to do is to find out what Large Ship looks like, and then offer your valuable suggestions with ** that ** model in mind.

And! when you ** do ** contribute, please put the suggestion for atomic power in the appropriate topic.

We are slowly adding specific topics for major aspects of Large Ship development as they seem needed.

This topic is for Radiation Protection for passengers and crew of Large Ship (Prime and all variations)

(th)

SpaceNut · 2022-02-25 19:44:31

First off the radiation shield does not need to be the size of the megosphere of earth which stretches 90,000 km above the earth and folds off as the solar winds push back the from of it by 20.000 km. The earth is 6,378 km radius or mean diameter of 12,756 km. The inverse function makes use of the radius as its unit of measurement for how fast it will fall off much like a logarithmic scale.

The earths field strength at the surface is 0.65 guass at the equator but falls off as it heads towards the poles to 0.25 guass. The earths core is 2.900 km to 5,000 km in size that generates the field which is much stronger but we are not generating a field from its center either.

We are designing a shield for a pea in comparison in size and strength to accomplish the same task of forcing the solar winds to go around it. Since we are so small we do not need as much of a field. With the shape of the ring edge being even smaller that faces towards the suns solar wind we can make use of a double direction field to make a balloon shaped field around all of the large ship.

The remaining radiation that might get through is caught by the water walls which last I check was only desired on 20% of the ship where as the magnetic field was design for a 360 field of direction. Radiation would pour into the ship like crazy if I designed something like that...

The space stations orbit crosses a field strength of about 0.1 gauss at its 400 km distance above the earth near the equator and falls off to 0.07 gauss. One tesla 10^0 is equal to 10^4 gauss. or 100,000 gauss.

https://en.wikipedia.org/wiki/Orders_of … tic_field)

you get close enough to a microwave and you will receive enough to cause and issue with your pace maker.
All of earths equipment works with a field that will be greater than the one we need to design.

SpaceNut · 2022-02-25 19:55:35

A there is no "fission gas core NTR" for propulsion or for power to supply a super conductor that requires cooling and is a ceramic in nature.

We do not need a 20T field which is Strength enough to levitate a frog...

10^−7 Magnetic field produced by residential electric distribution lines (34.5 kV) at a distance of 15 m

The field needs to be away from the hull for starters so that we get the benefit of distance to make the radiation go around it.

tahanson43206 · 2022-02-26 08:38:50

For SpaceNut re #6

You have made several statements that need support by references .

Please provide links to references that are recognized by PhD level individuals as valid.

The goal is to deflect iron nuclei traveling at 70% of the speed of light. What strength magnetic field can achieve that?

Please do not cite the Earth as the source of a magnetic field. The object to be protected is Large Ship.

Please provide a citation supporting the claim that a 20 Tesla magnetic field can lift a frog.

Please add units to the statement about residential electric lines.

Please note that the location of the source of the field must be close to the hull of Large Ship.

If you study the drawings of RobertDyck, you will see not protrusions at a distance from the vessel.

The radiation protection field generating equipment must be close to (or part of) the vessel itself.

(th)

tahanson43206 · 2022-02-26 08:46:28

For all ... contributions to this topic are needed and most welcome.

However, hand waving is not needed.

If you want to do hand waving, there are numerous other topics where posts would be welcomed with open arms.

This topic is intended to become a reference point for those who will be building and operating Large Ship in years to come.

The original design of Large Ship (see Large Ship topic of RobertDyck) does NOT attempt to protect against cosmic radiation.

It ** does ** attempt to provide protection against Solar flares.

This topic is intended to continue exploration of options until a solution is found that protects passengers and crews against Cosmic radiation arriving from all directions, as is the case in deep space.

A figure given by Quaoar for the energy of the ions of interest is:

To deflect the 2 GeV protons - the vast majority of GCR - you need a 20 Tesla field:

For Quaoar: Please provide a reference for the factoid you posted.

(th)

SpaceNut · 2022-02-26 12:03:55

here is the real references for a field of the 20 Tesla value and its a containment field not an outward directing. Which means they have reflecting materials.

Researchers Create the Most Powerful Magnet Ever Made on Earth: 20 Teslas

MIT ramps 10-ton magnet up to 20 tesla in proof of concept for commercial fusion making a ring of 17 identical magnets and surrounding structures—to contain a plasma

“To put it into context, the scale and performance of this magnet is similar to a non-superconducting magnet that was used in MIT experiments five years ago. The difference in terms of energy consumption is rather stunning: That magnet, because it was a normal copper conducting magnet, consumed approximately 200 million watts of energy. To produce the confining magnetic field, this magnet was around 30 watts.” That decrease—a factor of around 10 million—"makes it obvious why going to a high-field superconducting device or magnet now brings into bear net energy from fusion,” Whyte said.
Building something new: The magnet contains about 270 kilometers of superconducting tape wrapped in a spiraling pattern in 16 separate layers that are stacked together and sealed within a metal case, as shown in this animation. The 16 layers, which Mumgaard calls pancakes, are manufactured separately, in an assembly line fashion. The finished magnet weighs about 10 tons and is 10 feet tall and about half as wide.

Time and temp: The HTS magnet successfully tested at MIT is made from a material called REBCO, which stands for three constituent materials: rare earth, barium, and copper oxide. Its optimal operating temperature is a frigid 20 K, but relative to low-temperature superconductors, which require temperatures of a few degrees above absolute zero, HTS magnets require significantly less energy for cryogenic control.

So no value for the absolute cooling system...

Just how strong is a 20 T magnet? By contrast, a typical junkyard electromagnet that can lift cars and trucks is about 1 T, and a refrigerator magnet is about 5 mT. According to CFS, a 15 T magnetic field would be powerful enough to lift 31 Eiffel Towers, and a 19 T magnetic field would be powerful enough to lift 403 Boeing 747s.

so we can move it but at what distance?

video

The magnet is composed of 16 plates stacked together, each one of which by itself would be the most powerful high-temperature superconducting magnet in the world.

Fusion startup builds 10-foot-high, 20-tesla superconducting magnet

The magnet that was tested last week was about three meters tall and half that wide. It's powered by coils of a high-temperature superconducting material called ReBCO and operates at about 20 Kelvin. (In superconductivity, 20 K counts as high-temperature, as more typical superconducting materials need to be at less than 5 K.)
There are about 270 kilometers of superconducting material in the magnet, but the material is distributed among all these individual pancakes.

Energy requirements for (10 MW) was the Tokamak Fusion Test Reactor (TFTR) device at the Princeton Plasma Physics Laboratory, Joint European Torus (JET) in the UK, which has a radius of about 3 meters (m) and has made 16 MW of fusion power all of which were short duration that gave no net or less than supplied input value.

Needs quite a large area to house it and looks to be well over 50 MW input to force it to be capable of sustaining a net output that is positive for use.

Fabricated from 36 km of superconducting cable, this 1,000-ton magnet will drive 15 million amperes of current through the plasma, far more than anything that has been possible before.

RobertDyck · 2022-02-26 12:50:24

I posted this a few times, both in "Space radiation + counter measures" and "Large scale colonization ship". This is a paper from the University of Washington (the state). It shows how a mini-magnetosphere can be used for radiation protection. The magnetic bubble extends a few thousand km radius, but requires a total of 100 kW of electric power. One paper talked about a 50 kW version, but I believe the Large Ship will require the full-size magnetic bubble.

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

The deployment of a mini-magnetosphere (or magnetic bubble) around a spacecraft has recently been proposed as a means to couple energy from the solar wind to provide in-space propulsion. In so doing mini-magnetospheric plasma propulsion (M2P2) would have both high specific propulsion and high thrust while requiring only modest (kW/unit) power levels to sustain the mini-magnetosphere. In order to obtained sufficient thrust for a manned mission, the mini-magnetosphere is anticipated to extend out to several 100 km to a few thousand km in radius, possibly supported by several units using a total of ~ 100 kW. At this size, the mini-magnetosphere has the potential for not only deflecting solar wind particles, but also the energetic particles that comprise galactic cosmic rays (GCRs) and solar energetic particle (SEP) events. These energetic particles provide a significant radiation hazard for any extended manned mission in space. This paper presents initial design characteristics for using an M2P2 system as a radiation shield. Each unit consists of a magnet with a radius of 10 – 20 cm, with strength of a few kilogauss to possibly a Tesla. Embedded in each magnet is a plasma source that is used to expand the magnetic field. It is shown that the magnetic field fall off approaches 1/r as the plasma energy density approaches the magnetic energy density. The effectiveness in shielding as determined by the integral of B×dr can be more than an order of magnitude larger than the magnet by itself. Pulsed operation of the system is used to prevent modification of spacecraft trajectory and prevent build up of radiation belts within the mini-magnetosphere.

Quaoar · 2022-02-26 17:34:48

SpaceNut wrote:

A there is no "fission gas core NTR" for propulsion or for power to supply a super conductor that requires cooling and is a ceramic in nature.
We do not need a 20T field which is Strength enough to levitate a frog...
10^−7 Magnetic field produced by residential electric distribution lines (34.5 kV) at a distance of 15 m
The field needs to be away from the hull for starters so that we get the benefit of distance to make the radiation go around it.

It is also possible to use a lower magnetic field and inflate it with plasma creating an artificial magnetosphere:

I suggest this study by Ruth Bamford and her team, which addresses together radiation protection and artificial gravity.

https://arxiv.org/abs/1406.1159

It may be easily adapted to Robert's Large Ship

Quaoar · 2022-02-26 17:40:11

tahanson43206 wrote:

For all ... contributions to this topic are needed and most welcome.
However, hand waving is not needed.
If you want to do hand waving, there are numerous other topics where posts would be welcomed with open arms.
This topic is intended to become a reference point for those who will be building and operating Large Ship in years to come.
The original design of Large Ship (see Large Ship topic of RobertDyck) does NOT attempt to protect against cosmic radiation.
It ** does ** attempt to provide protection against Solar flares.
This topic is intended to continue exploration of options until a solution is found that protects passengers and crews against Cosmic radiation arriving from all directions, as is the case in deep space.
A figure given by Quaoar for the energy of the ions of interest is:
To deflect the 2 GeV protons - the vast majority of GCR - you need a 20 Tesla field:
For Quaoar: Please provide a reference for the factoid you posted.
(th)

It was a study published on Scientific American by Eugene Parker

https://www.scientificamerican.com/arti … travelers/

tahanson43206 · 2022-02-26 17:53:51

For Quaoar re #12

Thank you ** very ** much for this reference information!

I'll spring for the pdf if the local library here does not have a copy.

Will visit the library tomorrow. Scientific American is one of their mainstay magazines, but whether they have back issues that far is a question.
There wouldn't be too much demand for that issue, and storage space is expensive.
They ** may ** have it on microfilm (come to think of it) ... that is an alternative I've found before.
(th)

tahanson43206 · 2022-02-26 18:13:36

The NewMars archive contains a number of posts which make reference to the work of author Tom Heppenheimer.

I have pulled two links that refer specifically to the idea of using electrostatic force to deflect galactic ions (iron nuclei).

Re: Human missions » Radiation amount type risk mitigation » 2019-08-01 11:18:34

Human missions » Radiation amount type risk mitigation » 2019-07-31 08:36:54

(th)

SpaceNut · 2022-02-26 18:34:25

The shielding effect of surface magnetic fields of the order of ~ 100 s nano Tesla is sufficient to provide effective shielding from solar proton bombardment that culminate in visible discoloration of the lunar regolith known as "lunar swirls". Supporting evidence comes from theory, laboratory experiments and computer simulations that have been obtained on this topic.

10−9 Tesla = nano

https://en.wikipedia.org/wiki/Tesla_(unit)

http://www.unit-conversion.info/magnetic-field.html

100 s nano Tesla = 0.001 guass

Magnetic field produced by a toaster, in use, at a distance of 30 cm (1 ft)

Quaoar, My design starts with a loop of these high field strength neodymium-iron-boron (NdFeB) magnets around in a wreath like fashion that encircles the complete hull. Each separate loop is enhanced with coils wrapped in the shade around each loop to generate an ac field an rf as frequency is put into these booster coils. This creates 2 different direction field that reinforce the strength of each as they sum in all directions that is riding on the cage of neodymium-iron-boron (NdFeB) magnet rings.

SpaceNut · 2022-02-27 09:16:04

tahanson43206 wrote:

I agree that the proposal of RobertDyck to position mass along the sun-facing side wall of the habitat, addresses part of the problem.
Your observation about particles arriving from directions not aligned perfectly with the center of the Sun seems right, and you've provided a reference to study.

RobertsDyck's water wall or shadow is to stop secondary particles from the hull doing harm.

The current radiation shield is a 360 designed that extends to the central hub as well.

bd52d83c-9557-4187-8b19-81f42aafdf5c.e8715b76608520161d88c5e7ee4a9796.jpeg?odnBg=ffffff&odnHeight=612&odnWidth=612

It has this appearance for each of the permanent magnet loops
main-qimg-c0d68b7e98e275bfe2723bf59b1dbc87

The coils that are wrapped around each strengths and makes the overall field larger.
This is similar but different than my arrangement as this is only one of the fields wrapped that travels around the circumference of the ring.
There would be more that covers the loops that wrap the ring in the small hull of the rings 19m x 2.34 m.

The magnetic rings and the coils are all external and rise above the hull to focus the field externally so that it projects outward.

This is what happens to iron when it meets a magnetic field
51P57azGAnL._SY445_SX342_QL70_FMwebp_.jpg

Its the centripetal force of the rotation that shed the particles since the mass is tiny.

The main issue for electrical fields is the power requirement and if we can make a standard superconductor coil for the application then the power for those coils in the shadow will not need the cooling that those in the sun will. This is a trade off for field generation. Can we couple a cooling loop as well from the cold side to the warm and isolate that direct heating that makes life better for the fields creation.

edit

Thinking about the central hub protection and need for additional shielding. I am thinking that the permanent magnet on the top in concentric circles will provide a means to couple the more intense electrical shield across it. The sides of the cylinder that makes up the stem of it I would align up and down the body more straight lines of the same Magnets as that will focus the field as to having poles and that will allow for the over all fields to be cross connecting at distance from the hull of the ring.

The purpose of a multi stage system is a part of the design that while in the megosphere of the planet we do not require the same field size and strength as we would need in open space.

RobertDyck · 2022-02-27 14:58:32

SpaceNut wrote:

RobertsDyck's water wall or shadow is to stop secondary particles from the hull doing harm.

It's not for secondary particles, it's for solar protons. The mini-magnetosphere will provide 360° protection against all radiation, including GCR. My hope is it will reduce GCR to equal that in ISS. ISS is inside the Earth's magnetosphere. Radiation in interplanetary space is twice to three times that of ISS, depending whether the Sun is at maximum or minimum. But that doesn't eliminate all radiation. Because a Solar Proton Event is so intense, even after deflecting most radiation the remaining protons will still be very dangerous, potentially lethal. So the water wall is a secondary layer of protection, but it's for solar protons, not secondary particles.

When radiation hits solid material it can cause either particles to be split off the solid material, or the radiation particles can split. Light elements are preferred for heavy ion GCR because they minimize secondary particles. Liquid hydrogen is the best. Water is very good. Mineral oil is also very good, it has carbon instead of oxygen which is slightly lighter than oxygen. But an SPE is mostly protons, and they don't have as much energy as GCR. The greatest point is plasma of a mini-magnetosphere is not expected to cause secondary particles.

SpaceNut · 2022-02-27 15:54:34

Interesting
I went googling for what is the difference for a proton versus a photon as I was under the impression that they were the same thing.

Self educating is fun...

http://www.ph.surrey.ac.uk/satellites/m … al1_3.html
Magnetosphere & Solar Protons

Solar protons, being charged particles, will follow a path to the Earth along the magnetic field lines from the Sun. If the Earth happens to lie on a field line which is connected to the flare region on the Sun, the flare particles will arrive at the Earth promptly causing a solar-particle event (SPE).

https://journals.sagepub.com/doi/pdf/10 … 1000900612
Low-dose Photon and Simulated Solar Particle Event

https://escholarship.org/content/qt5bj0 … 965a99.pdf
The Impact of Solar Particle Events on Radiation Risk for Human Explorers of Mars

so its the energy level of the particle

Quaoar · 2022-02-28 04:38:09

RobertDyck wrote:

SpaceNut wrote:
RobertsDyck's water wall or shadow is to stop secondary particles from the hull doing harm.
It's not for secondary particles, it's for solar protons. The mini-magnetosphere will provide 360° protection against all radiation, including GCR. My hope is it will reduce GCR to equal that in ISS. ISS is inside the Earth's magnetosphere. Radiation in interplanetary space is twice to three times that of ISS, depending whether the Sun is at maximum or minimum. But that doesn't eliminate all radiation. Because a Solar Proton Event is so intense, even after deflecting most radiation the remaining protons will still be very dangerous, potentially lethal. So the water wall is a secondary layer of protection, but it's for solar protons, not secondary particles.
When radiation hits solid material it can cause either particles to be split off the solid material, or the radiation particles can split. Light elements are preferred for heavy ion GCR because they minimize secondary particles. Liquid hydrogen is the best. Water is very good. Mineral oil is also very good, it has carbon instead of oxygen which is slightly lighter than oxygen. But an SPE is mostly protons, and they don't have as much energy as GCR. The greatest point is plasma of a mini-magnetosphere is not expected to cause secondary particles.

Mini magnetosphere is better but may have a failure, so even if our ship has a good mini-magnetosphere, I think she must have also a storm cellar with a 20-25 cm of water wall (or some hydrocarbon material), which is good to stop 200 MeV solar protons. A storm cellar for all the people surrounded by 20-25 cm of water is a big mass penalty, but we can minimize it with a clever design:

if our ship uses aerocapture at both ends, we can design a water-cooled double-layered thermal shield with a porous steel external plate. Before aerocapture, we only have to pump the water of the cellar in the cavity of the thermal shield, which will be lighter because it doesn't need thermal tiles.

If our ship uses propulsive insertion at bot ends, we can use LOX-methanol rockets, which have a F/O ratio of almost one and an Isp between the LOX-CH4 and the LOX-RP1 rockets. During the trip, the methanol is stored in the wall of the cellar to protect passengers and crew from solar protons event, and only before the orbital insertion it is pumped in the tank.

Last edited by Quaoar (2022-02-28 04:56:26)

tahanson43206 · 2022-02-28 07:33:20

For Quaoar re #19 and related items ...

First, thank you for your continued support of development of this topic!

A short time ago, you provided a link to an article published in Scientific American in 2006. One of our local libraries maintains an archive of older material for situations just like this, so I visited yesterday. The staff person who helped me was most gracious. The technology for display of microfilm has advanced significantly since I last visited this library. The film reader now feeds light into a digital camera, which feeds software that formats the data onto a large HDMI display screen. The data is automatically adjusted for optimum sharpness of the image, replacing the old technology, which required adjustment of the lens system on the physical light display.

The staff person went way beyond the minimal service that might have been offered, by loading the film onto the machine, locating the issue of interest, and even setting the display on the table of contents. From there, I found the article you had recommended, and in just a few minutes, realized this article is worth the $8.00 (USD) that Scientific American wants for a pdf copy. I returned home and ordered the pdf from Scientific American's web site. However, after making my payment, I did ** not ** receive a link to the pdf file. Instead the automation informed me that my order had been accepted.

since this happened on a Sunday (in this region) I am guessing the order has to be processed by a human being before the pdf file is released.

***
Your post #19 contains both good news and bad news .... The good news is that you are providing a well formed overview of the subject of radiation protection, with suggestions for use of various materials to help, including propellant, which might be positioned so as to protect passengers.

The bad news is that it appears you may have missed a few details in your (no doubt rapid) reading of the Large Ship topic. Since it would take a normal person a month to read all those posts, your rate of reading is truly impressive. Many years ago I discovered that I could read rapidly, but that I would retain nothing from the material read. What I ** do ** remember is having performed the experiment. At the time, I was very proud of having passed all that data through my brain in a short period of time. It was only later that I realized I'd omitted the processing (thinking) step, so had no memory of the material.

Thus, if you did indeed pass two years of posts in the Large Ship topic through your optical subsystem, I think it is unlikely much of that material went through the deeper processing subsystem, in order to overlay previously stored material.

Your post #19 reveals that you do not realize that the idea of bringing a 5000 ton ship full of 1000 passengers and crew anywhere near an atmosphere of ANY celestial body is tantamount to giving a kilogram of fentanyl to a patient, when 10 ml at 50 micrograms per ml is a medically advisable dose for surgery.

Happily, the work of Dr. Johnson is available for your study. You will see his most recent draft of a document on chemical propulsion for Large Ship if you visit the topic GW Johnson Postings, and look for the most recent post. You will find a link to a document stored in the NewMars Dropbox

Please ** do ** take a bit of your (I understand limited) time to better understand the concepts in play for management of the flight of a 5000 ton space vessel between Earth and Mars.

(th)

Quaoar · 2022-02-28 08:17:20

tahanson43206 wrote:

Your post #19 reveals that you do not realize that the idea of bringing a 5000 ton ship full of 1000 passengers and crew anywhere near an atmosphere of ANY celestial body is tantamount to giving a kilogram of fentanyl to a patient, when 10 ml at 50 micrograms per ml is a medically advisable dose for surgery.
Happily, the work of Dr. Johnson is available for your study. You will see his most recent draft of a document on chemical propulsion for Large Ship if you visit the topic GW Johnson Postings, and look for the most recent post. You will find a link to a document stored in the NewMars Dropbox
Please ** do ** take a bit of your (I understand limited) time to better understand the concepts in play for management of the flight of a 5000 ton space vessel between Earth and Mars.
(th)

Probably a 5000 ton spaceship is to big and heavy for aerocapture given the square-cube law, but I was not the one who proposes aerocapture, because it was in the first post of the topic:

"I mentioned this elsewhere, but we need a dedicated topic. This is ship intended to carry a large number of passengers. Intended to travel from Earth orbit to Mars orbit and back. Aerocapture at both planets. Heat shield made of Nextel 440 fabric, which is the fabric that NASA's Ames Research Center selected for advanced thermal blankets called DurAFRSI. That's a synthetic ceramic fabric. Carbon fibre can withstand more heat, but carbon fibre is not as durable so not as reusable. Rotation for artificial gravity; a wheel behind a giant fabric umbrella heat shield."

Last edited by Quaoar (2022-02-28 08:17:47)

tahanson43206 · 2022-02-28 08:26:40

For Quaoar ... re Post #21 ....

Thank you for your patience! Your support of this project is already valuable, and I will do my best here to try to explain what happened over two years...

You are absolutely right, that the visionary (RobertDyck) started out with a magnificent concept that had no possibility of becoming reality. However, over two years, and with input that he has carefully studied, he has made incremental changes to details that do not impact the stability of the vision.

He has quietly let the idea of aerocapture fall by the way side, and if you had not brought it back into view, it would have stayed there.

For that reason, I invite you (again) to read the recent work of GW Johnson. Unlike many of us (like me) you have shown the ability to understand the work of GW Johnson. Please take the time to study the work and to comment upon that. Your study of two year old opening gambit posts is important, but to help us now, it will help to catch up with the current state of play.

Since this is the Radiation topic, I will repeat that I am grateful for your having brought the Scientific American article to our attention. I have ordered the pdf of the article and hope it actually arrives.

Should the article arrive, I will immediately set about requesting permission to share it with the members of this forum.

(th)

RobertDyck · 2022-02-28 08:37:33

Quaoar:
Thank you for joining the conversation. I chose 12cm of water because Robert Zubrin said that was required, and that was without any mini-magnetosphere. If 20 or 25 cm are required, we'll use that. But let's not plan for excessive weight without proof it's necessary.

The large Ship will have cabin windows on the Sun side. This obviously means holes punctured through the water wall. I have said these windows will have two panes with the space filled with mineral oil. That has been used to fill the gaps between panes for windows of a radiation "hot cell" since the 1950s. Mineral oil is made from a non-organic source such as petroleum. It's clear and colourless like water, but with a higher optical index than water. Optical index is close to that of glass, making the surface where oil meets glass less visible. Lighter elements are better for stopping heavy ion radiation, because lighter elements don't produce secondary radiation. Water is H2O, mineral oil is a distillate, there are various chemicals in it and various grades of mineral oil, but one is liquid paraffin which has a chemical formula the same as polyethylene but shorter. Liquid paraffin is a carbon chain where each carbon atom has a single bond to the next carbon atom on each side, and two hydrogen atoms bind to each carbon atom. The end of the chain has another hydrogen. So the chemical formula is H2C which repeats. Again, the only difference is liquid paraffin is shorter chain so it's liquid, while polyethylene is longer chain so solid. Oxygen has atomic weight 15.999 while carbon has atomic weight 12.011. Again lighter weight is better for radiation shielding. Mineral oil is a distillate, so not all will be liquid paraffin. Some will be other chemicals with more complex molecular structure, with branches and hex-rings. But for the purpose of radiation shielding, you get the idea.

The window should be aluminum oxynitride (ALON), a strong material, highly resistant to damage from micrometeoroids. It will be more than two panes, using the Cupola on ISS as an example. It would have 2 outside panes with vacuum between, so the outer pane could be replaced if damaged.

Yes, I did say the ship would use aerocapture at both ends. That greatly reduces propellant required. The only issue is whether the new constellations of satellites for internet will create a cloud in Low Earth Orbit which obstructs aerocapture. If these satellites get in the way, we can't aerocapture without plowing through them like a snow plow. I don't think the owner of the satellites would appreciate that. And they could damage our ship's heat shield. A heat shield for aerocapture does not have to be as robust as for atmospheric entry, but if the aerocapture shield is fabric then impact with these satellites could tear through.

The white tiles on the back of Space Shuttle were replaced quickly. They were delicate, many shook off during launch. They were replaced with thermal blankets. The white tiles were highly pure silica foam. They were not glass, they were 99.9% pure silica (silicon dioxide, SiO2). The black tiles had a glaze, the white tiles did not. The white tiles were replaced with thermal blankets, actually a quilt. The quilt was made of normal fibreglass fabric backing, which touched the aluminum alloy skin of the shuttle, but the top fabric was the same 99.9% pure silica as the tiles. The fibre batting that filled the quilt was also 99.9% pure silica. This was called Advanced Flexible Reusable Surface Insulation (AFRSI).

Near the end NASA's Ames Research Centre developed a more advanced thermal blanket. Durable Advanced Flexible Reusable Surface Insulation (DurAFRSI). It was also a quilt, but not silica. Both the top and bottom fabric was Nextel 440, a synthetic ceramic fibre. And batting was Saffil, high purity fibres: 96% alumina / 4% silica. This was covered with a mesh of Inconel 617 sewn on, and Inconel 617 metal foil was brazed onto the mesh. The result was smooth metal outer skin for an aerodynamically smooth surface. This was developed late, never installed on Shuttle, but was tested by the Air Force on X-37. What I suggest as the heat shield for aerocapture is Nextel 440 fabric. Just the fabric from this quilt, none of the rest. It's already heat shield material. It doesn't have to resist the extreme heating of entering Earth's deep atmosphere at interplanetary speed; it just has to skim the upper atmosphere enough to slow the vehicle sufficiently to enter orbit. So thinner atmosphere, and less change of velocity, so less heat produced. However, this fabric will tear if it hits a satellite.

RobertDyck · 2022-02-28 09:00:54

tahanson43206 wrote:

He has quietly let the idea of aerocapture fall by the way side, and if you had not brought it back into view, it would have stayed there.

No, the idea has *NEVER* fallen by the way side. kbd512 has been insistent that everything has to be his way, and he doesn't like aerocapture. I stopped arguing with him, any argument with him is like hitting your face into a brick wall. In the end I suggested he design his own ship, and stop trying to fundamentally change mine. That's how we got the discussion thread "A More Practical Interplanetary Colonization Ship". Whether his is more practical is highly debatable, but that's what he called it.

My design philosophy has always been something that some people do not understand. My philosophy is start by assuming whatever you're working on can be done, start with something visionary even if parts may appear impractical, then fine tune to something practical. Many people have criticized this as not practical, but those people have *NEVER* been able to develop anything new. Those are the people with the attitude that "if it hasn't been done, it can't be done". If you can't find it on store shelves right now, then it's impossible. That attitude will never accomplish anything. The National Advisory Council on Aeronautics (NACA) was created in 1915 because commercial companies did not want to invest in anything without a guaranteed return on investment. When you develop something new, there's never any guarantee. So the NACA was given the task to develop high-risk/high-payoff technologies. Not high-risk of human lives, but high-risk in terms of getting your money back. So the NACA was created to fight against the same people who criticize me. After Sputnik orbited the Earth the first time, the NACA was converted into NASA. The mandate of NASA still to this day has the mandate of the NACA. That's what it's for. So again, anyone who has the idea that "if it hasn't already been done, then it can't be done" is someone who doesn't belong in NASA. And doesn't belong on this project.

To quote Albert Einstein: "Great spirits have always encountered violent opposition from mediocre minds."

Quaoar · 2022-02-28 10:59:53

RobertDyck wrote:

tahanson43206 wrote:
He has quietly let the idea of aerocapture fall by the way side, and if you had not brought it back into view, it would have stayed there.
No, the idea has *NEVER* fallen by the way side. kbd512 has been insistent that everything has to be his way, and he doesn't like aerocapture. I stopped arguing with him, any argument with him is like hitting your face into a brick wall. In the end I suggested he design his own ship, and stop trying to fundamentally change mine. That's how we got the discussion thread "A More Practical Interplanetary Colonization Ship". Whether his is more practical is highly debatable, but that's what he called it.
My design philosophy has always been something that some people do not understand. My philosophy is start by assuming whatever you're working on can be done, start with something visionary even if parts may appear impractical, then fine tune to something practical. Many people have criticized this as not practical, but those people have *NEVER* been able to develop anything new. Those are the people with the attitude that "if it hasn't been done, it can't be done". If you can't find it on store shelves right now, then it's impossible. That attitude will never accomplish anything. The National Advisory Council on Aeronautics (NACA) was created in 1915 because commercial companies did not want to invest in anything without a guaranteed return on investment. When you develop something new, there's never any guarantee. So the NACA was given the task to develop high-risk/high-payoff technologies. Not high-risk of human lives, but high-risk in terms of getting your money back. So the NACA was created to fight against the same people who criticize me. After Sputnik orbited the Earth the first time, the NACA was converted into NASA. The mandate of NASA still to this day has the mandate of the NACA. That's what it's for. So again, anyone who has the idea that "if it hasn't already been done, then it can't be done" is someone who doesn't belong in NASA. And doesn't belong on this project.
To quote Albert Einstein: "Great spirits have always encountered violent opposition from mediocre minds."

Another possibility is the aeromagnetic capture, using a plasma mini magnetosphere as a brake like an aerocapture ballon: the plasma ions interact with the neutral molecules of the higher atmosphere, slowing down the spaceship via ion-neutral momentum exchange :

https://www.nasa.gov/directorates/space … netoshell/

David Kirtley has calculated that a 690 kg device (case, electromagnet, battery and cable) can aerocapture a 60 Ton spaceship sparing 20 tons of thermal shell mass.

What is intriguing is that the same device might also be used as a radiation shield during the trip.

Last edited by Quaoar (2022-02-28 11:01:50)

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