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#51 2021-12-30 18:42:49

tahanson43206
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Registered: 2018-04-27
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Re: A More Practical Interplanetary Colonization Ship

For SpaceNut re #50

Interesting concept !!!

For kbd512 ... thanks for the link to the paper on microwave and plasma propulsion ...

Nothing captured when I tried to copy from the pdf ... The section I tried to copy was the Conclusion.

The paper did seem to support your belief the beam could be kept tight, instead of dispersing as Calliban had correctly predicted.

Indeed, the graphs in the paper show the normal dispersion that would be expected, followed  by the benefit of one magnetic nozzle, followed by the addition of the second nozzle.

One (to me unexpected) result of this work is the potential to deliver useful impulse to large ships as well as small ones.

Additional thought .... for a large ship headed to Mars, it occurs to me that a beam transmitted from the Moon would have the ability to provide impulse to a vessel some distance away.  The distinct advantage of such a system is the stability of the platform.

(th)

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#52 2021-12-30 19:07:44

kbd512
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Re: A More Practical Interplanetary Colonization Ship

tahanson43206,

I think the "knowledge gap" is that you're firing a magnetized beam of charged particles into an electromagnetic cone on the receiving end, which means that less than perfect alignment is still not wildly detrimental, and that due to orbital mechanics, the large ship passes close by the LEO-based MagBeam station whereupon a succession of said stations fire their plasma beam for a very brief period of time and then when the ship's higher energy elliptical orbit brings it back around for another "go" at the MagBeam stations, the process is repeated until escape velocity is achieved.  The ship and station are very close to each other during the firing sequence.  The orbit path of the large ship is neither circular nor is it a spiral.  This is what prevents us from needing insane amounts of energy to do a single impulsive transfer burn, although effectively we're setting up an entire series of small impulsive burns that add impulse bits to the large ship's total velocity until it achieves escape velocity, which occurs over a period of about 2 weeks.  Since the ship is heavily shielded internally, it can transit through the Van Allen Belts multiple times without killing anyone.

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#53 2021-12-31 03:09:30

Calliban
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Re: A More Practical Interplanetary Colonization Ship

Two questions come to mind:

(1) Should we have a dedicated freight interplanetary transportation concept?  This can be slower than a man rated interplanetary ship.  It does not need radiation shielding.  It does not need artificial gravity.  Plasma beam accelerators could raise the orbit of payloads over a period of months if necessary.  Very soon in the Mars colonisation effort, it will also be desirable to be able to ship freight in both directions.  The first two exports of significance from Mars will be LOX/CH4 bipropellant for use in Earth orbit and water.

(2) Of the 10km/s of dV needed to reach Low Earth orbit, about 60% is required to achieve orbital velocity.  Could Mag Beam stations be used to accelerate a vehicle to orbital velocity?  If so, then a Starship upper stage could presumably take off from Earth surface, function in booster mode until reaching an altitude of 100km and then unfurl a mag sail, allowing a plasma accelerator in orbit to boost it to orbital velocity.  This would require precise timing of course and the plasma pressure would need to be great enough to overcome exospheric drag.

Last edited by Calliban (2021-12-31 03:29:43)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#54 2021-12-31 05:07:55

kbd512
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Re: A More Practical Interplanetary Colonization Ship

Calliban,

Yes, we will have dedicated freighters.  I already stated that in previous posts, for all the reasons you listed.  I'm still solidifying how this will work in my head, thinking about the various aspects of operations and how to use MagBeam to deliver cargo in addition to people.  Given that both power and propulsion are provided by the MagBeam stations, it might make more sense to deliver much smaller payloads more frequently.  Apart from the electromagnetic rocket nozzle and avionics, the freighters don't share much else in common with the transports.  Anyway, this would be especially important for shipping water and metals.  You need a comparatively small quantities of LOX/LCH4 for propulsive landings, but in this colonization concept shipment is mostly one-way.

We won't be ferrying Starships to and from Mars, because that requires additional equipment / power / labor that detracts from the colony building effort.  It's not a good trade if colonization is the goal.  Earth is the factory.  We don't need to transport anything but the crewed transport ships back to the factory.  The small engineering section of each freighter, which is essentially a large satellite, could be secured to the colonization ship for return to Earth.  The ships will be returning with a skeleton crew and minimally loaded since most of the food and water will be taken by the colonists to the surface of Mars.  We're talking about more than half of the weight being offloaded at Mars.

Using Starship, over 90% of everything delivered to LEO or beyond is propellant.  90% of the power consumed on Mars is used to send Starships back to Earth.  We can't afford to refuel ships that size and build a colony at the same time.  Something has to give.  As Elon Musk would say, the requirement is dumb.  It's better to burn Starship service life delivering payloads to LEO, allowing them to reach the end of their as-designed service life within a year of operations.  That way the hardware is always fresh / new and hasn't been sitting in a dust bowl for 2 years before it can be re-flown.  A fraction of the Starships must be built under this scheme, which leaves more money for payloads and putting butts in seats.

Rocket Labs is building Neutron with Archimedes LOX/LCH4 engines that are more suitable for retro-propulsion.  Archimedes produces about 55% of the thrust of a Raptor engine, so very similar in output to a Merlin engine, and uses the gas generator cycle like a Merlin.  It should be on par with Merlin, weight and size-wise.  If Archimedes development tanks or Rocket Labs tanks, then we revert back to using Merlin engines since they're effectively single-use / throw-away under this scheme.  Merlin's thrust is nearly identical to that produced by Archimedes, so we benefit from shipping a storable fuel (RP-1) and only have to keep the cryogenic oxidizer frosty cold.

The landers will use disposable inflatables heat shields and will be based upon Starship, but much shorter, to deliver the colonists and their consumables (100t for the colonists and their belongings, 200t of water, 150t of freeze dried food; 450t total landed mass, but it only weighs 171t on Mars).  The rest of the food and water is staying with the ship's crew for return to Earth.  9 Archimedes or Merlin engines will deliver power and redundancy.  So, visualize a much shorter Starship was equipped with 9 Merlin engines.

As to your second question, MagBeam would require a crazy amount of power due to the short interaction time, but in theory it could also provide the speed of an upper stage.  That said, I think it's best used to perform TMI for payloads already in LEO.

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#55 2021-12-31 07:25:15

tahanson43206
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Re: A More Practical Interplanetary Colonization Ship

Magnetic Sails have come into view in this topic ...

A quick check with Wikipedia revealed that Dr. Zubrin was/is credited with early work in this field.

Other entries in Wikipedia cover other aspects of the idea...

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

MagBeam is the specific technology recently proposed for spacecraft propulsion.

A detail not covered in any of the write ups I found so far is how a particle interacting with a magnetic field causes feedback (force) on the source of the magnetic field.

If anyone runs across an online (or printed) explanation of how that happens I'd appreciate a link.

It is clear by observation that a magnetic field can pull or push.  The pull is particularly evident in electric motors, which incorporate fixed coils to generate magnetic fields, and rotating components that are attracted by magnetic fields.

Push by a magnetic field  requires an equal magnetic field to be present in the object to be pushed.

Newton predicts that force applied to the moving object by a magnetic coil will be felt by the magnetic coil in exact equivalence to whatever force is exerted by the magnetic coil.

However, ** how ** that happens is not at all clear.

A magnetic line of force is a conceptual rendering of the underlying physics that is helpful for human attempts to grasp the physics.

I hope there exists an explanation of how a force (magnetic in this case) can exert an influence on a foreign object, and reflect that influence back to the source of the field.

A string may be used to pull an object.  In that case, the forces at work are electrostatic.  They consist of the binding forces between molecules of the string.  In ** that ** case, it is easy to conceptualize the equal distribution of force back and forth on the string.

A magnetic "line of force" is NOT the same as the sequence of molecules making up a string.

It would ** appear ** that a magnetic "line of force" works in both directions, similar to a string of molecules.

However, I have not had the good fortune to run across a discussion of that phenomenon.

(th)

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#56 2021-12-31 10:18:22

Quaoar
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Re: A More Practical Interplanetary Colonization Ship

GW Johnson wrote:

Hi Quaoar,  long time no see!

Bigelow laid off all (88) employees in March 2020,  blaming it on the pandemic.  The expressed intent was to restart and rehire after the pandemic.  So far that has not happened.  To me,  it looks like the pandemic will never end,  it will morph into something endemic,  like the various flus,  mumps,  measles,  etc. 

The longer they stay closed,  the more likely it seems to me that they will never reopen.  Those layoffs started a decade earlier.  It was just the last 88 that went in March 2020. That suggests other troubles besides the pandemic.

GW

Now I'm very busy with mass vaccination program, so I've few time to follow the forum.
I'm very sad for bigelow. They have creativity and their big habitat redesigned with centrifugal decks could be very good for an orbit-to-orbit ship, like your rigid baton.

Happy new year for all from Italy

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#57 2021-12-31 11:50:00

SpaceNut
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Re: A More Practical Interplanetary Colonization Ship

It is good to see you post even if its not very often Quaoar and the front-line does come first for all nations.

For tahanson43206 the magnetic field is to culminate (focus) the force into a less dispersed output for a given meter to force from the exhaust of the engine. Think how a microwave works as the beam would spread out if it was not for the permanent magnets inside the magnatron.

The beam is not hitting a solar sail but a collector dish to reflect into the engine to further accelerate them. Think more like the startrek deflector dish as its more like a parabolic dish.

As for cargo (items you need later) versus life support cargo (those things needed now) lets not mix the two distinct concepts to make it stay simple.

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#58 2021-12-31 12:17:15

kbd512
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Re: A More Practical Interplanetary Colonization Ship

SpaceNut,

The Star Trek main deflector dish a good analogy.  The accelerated plasma beam from the MagBeam station bounces off the electromagnetic "deflector dish", and that is what imparts thrust to the powered spacecraft.

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#59 2021-12-31 12:18:31

kbd512
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Re: A More Practical Interplanetary Colonization Ship

Quaoar,

Thanks for stopping by.  Happy New Year!

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#60 2021-12-31 12:35:22

SpaceNut
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Re: A More Practical Interplanetary Colonization Ship

RobertDyck's latest find

maxresdefault.jpg

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#61 2021-12-31 15:38:40

kbd512
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Re: A More Practical Interplanetary Colonization Ship

SpaceNut,

Yes, I saw that about a week ago.  It's a badly needed development.  Artificial gravity prevents serious health issues that drugs and exercise alone cannot overcome.

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#62 2022-01-01 07:51:16

tahanson43206
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Re: A More Practical Interplanetary Colonization Ship

For kbd512 re this particular topic ....

The challenge of designing and building a successful counter-rotating passenger space craft is one that should allow this topic to attract some innovative thinking as it goes along.  You have already set a high standard for what you will be doing with this topic as it continues.

I am looking forward to seeing a variety of technical solutions to various problems facing the design team, as they are posted.

The design of the bearing structure is of particular interest to me, and hopefully to others who are and will be following your progress.

The nature of bearings in use in space for gyroscopes is potentially available for study.  Gyroscopes have been used for spacecraft attitude for decades.

How they are made, how they are lubricated, and how power is applied to the rotating component if drag occurs are all subjects that might be posted in this topic, with your support and encouragement.

Beyond that, there is the interesting technical problem of how to apply thrust to a large rotating structure.  This rotating structure will be the largest counter-rotating device ever attempted by humans in space, and it will be inspiring to young people of every Nation as it unfolds.

One possible approach that might turn out to have some value, is to turn the vessel so that thrust is applied to the axis of rotation equally along the entire length of the axle, so that the rotating habitats are aligned in the direction of acceleration, and the forces on the bearing surfaces are equally distributed.

Todo: Insert image link here, to show that this might look like

(th)

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#63 2022-01-01 07:59:05

tahanson43206
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Re: A More Practical Interplanetary Colonization Ship

For kbd512 re topic ...

I hope you will continue advancing your vision of how a MagBeam system might be used to accelerate a large space vessel.

In my first round of investigation of what this idea might entail, I learned that one of the early concepts was to deploy a single wire in a huge loop in space. As I understood the description of the idea, current flowing through the wire would generate a magnetic field which would tend to straighten the wire into a perfect circle of many kilometers length.  It was imagined that ionized particles might cause the magnetized wire to respond by moving with the momentum of the particles.

At the hub of the energy supply, located in the rim of the huge loop, the forces felt by the wire would be applied to the mass of the hub.

The force applied by the wire needs to be less than the shear strength of the wire of course.

I got the impression that the force that might be generated by a kilometers long wire might be a few grams.

Perhaps you have read something that gives you confidence the MagBean capture antenna would be able to transfer more than a few grams.

If you have found any real-Universe experiments showing how this system might work, I would certainly be interested in those as well.

(th)

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#64 2022-01-01 10:14:20

SpaceNut
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Re: A More Practical Interplanetary Colonization Ship

Th you are referencing several different concepts of power generation to control of the exhaust of the engine.

post 9 note b is about a means to create power while in the earths magnetic field which will be useless after a bit since the field drops off quite when we still are inputting energy into the engines to escape earths gravity well.

post 23 is talking about failure mode of a solar panel indirectly as its made of many fine wires easily broken, of course the effects of the panels operation to collect power is not as good in orbiting as the rotation around earth interrupts the suns ability to hit the panels and once we leave earths orbit we need to ensure that the panels do align towards the sun. Energy required is a fixed amount so if we need more energy than what the panels are delivering we need to store it which means a huge mass penalty for using solar for the megabeam engines use.

post 30 has already been discarded for the same reason

Which means we are onto other power sources and means to gain energy when the engines need it the most.

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#65 2022-01-01 10:38:08

tahanson43206
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Re: A More Practical Interplanetary Colonization Ship

For SpaceNut .... re #64

This topic was created by kbd512, and your post #64 certainly gives him a lot to think about!

I'll be watching this topic with great interest to see what happens next!

(th)

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#66 2022-01-01 14:12:48

kbd512
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Re: A More Practical Interplanetary Colonization Ship

SpaceNut,

ISS solar panels have been in continuous operation for decades now.  I think it's safe to say that damage to solar panels from tiny pieces of space debris is not frequently catastrophic in nature, or ISS would have had severe power-related problems by now.

The key points to MagBeam are as follows:

1. The MagBeam satellites operate in LEO, where they are below most of the radiation form the Van Allen belts.  Operating from LEO means the satellite only has to be lifted to LEO, which cuts down on propellant requirements.

2. When the MagBeam satellites fire the plasma beam into the magnetic lens aboard the ship, the two spacecraft are in close proximity and below the Earth's Van Allen belts, because the orbital modification of the ship is from circular to elliptical.  It's not "spiraling out".  The magnetic field is still present, but the plasma beam dispersion and distortion from being fired through the plasma / radiation field created by the solar's wind interaction with Earth's magnetosphere is considerably reduced.

3. MagBeam requires "fast discharge", but not "fast charge".  This decreases wear and tear on the batteries, since both fast charge and fast discharge increase wear rates.  I accounted for battery capacity by doubling up the mass allocated to batteries, such that we only have 50% Depth-of-Discharge for each "shot".

4. The entire impulse bit of 3km/s does not have to be provided at one time, which drastically lowers the stored power requirement.  The satellite battery mass is then reduced to the amount of power that it can store and deliver to the payload / ship over a single orbit.

5. A series of MagBeam satellites / stations can keep the tonnage of individual satellites below the payload performance capabilities of a single Starship, so no orbital assembly is required and even if a catastrophic event disabled one of the satellites, all capability to launch is not lost due to a single catastrophic event.

To that last point, now that we've scaled down the large ship to something we can adequately shield using a tonnage of water and food appropriate for the expected 200 day transit time, all major components of the large ships fall well within the payload performance capabilities of Starship (all major ship components are comfortably under 100t).  We still need multiple flights to deliver the food and water, but most of that food and water is going with the colonists to Mars after they arrive, so those provisions become emergency survival supplies for the colonists once they're on Mars.

tahanson43206,

I've already dropped the idea of using Electrodynamic Tethers and M2P2 for propulsion.  They seem very promising and will be revolutionary if we can implement them in a practical manner, but the operational complexities are poorly understood and the technology less well developed.  Plasma accelerators are a well developed technology used in nuclear fusion and plasma physics research, because it's an area of active scientific study for Earth-bound fusion applications with lots of real tangible hardware behind it.  Electrodynamic Tethers and M2P2 seem to fall outside our wheelhouse of readily understood and thoroughly tested propulsion principles, specifically because most research focuses on spacecraft electric propulsion providing better specific impulse to existing engine types and more Newtons of thrust per kilowatt of input power.

I still like the Electrodynamic Tethers and M2P2 concepts, but I prefer a propulsion technology that will be equally useful for commercial satellites, scientific probes, cargo ships, and large transport ships.  MagBeam can serve all of those use cases equally well.  If you can get your payload to LEO, then the MagBeam satellite constellation can send it wherever you want it to go.  The elimination of chemical rocket upper stages is a future aspirational goal, and far less important to practical economic operations when you have fully reusable chemical rockets like Starship.

We don't have any chemical or nuclear thermal rocket engines that substantially alter the economics of sending large payloads to other planets.  We have chemical that tops out at 450 seconds of specific impulse and solid core nuclear thermal tops out at 1,000 seconds.  This concept is 10,000 seconds using ionized Hydrogen gas.  All input power and propellant stays aboard the MagBeam stations in LEO, rather than on the powered spacecraft, so the equations for figuring out how much payload you can send are as simple as they can possibly get.  All the electrical technology (solar panels, batteries, PMAD) use existing technology.  It does not require nuclear reactors or any other power generating technology we have not already developed to the degree required.  MagBeam is an electrical engineering task, not a scientific research and development task.  Since there are no nuclear reactors involved, there will be no objections from other countries over having nuclear reactors orbiting overhead, and no money spent on reactor development and testing for that purpose.  We still need nuclear reactors on Mars, but those units will be of the truck-transportable variety that our military and other countries are already developing for Earth-bound applications.

Removing insane power requirements, highly experimental propulsion technologies (no matter the ultimate promise of Electrodynamic Tethers and M2P2, which equates to another order of magnitude reduction of propulsion mass on top of MagBeam), and objectionable power delivery methods improves the likelihood that we can develop this concept without major environmental or political roadblocks.  I want to spend money on real engineering, rather than fighting with regulators and the general public.  The use of solar panels and batteries was another tip-of-the-hat to practicality.

Overall practicality of the solution to the problem of transporting thousands of people to another planet is the end goal of this topic.  It's not to advance any pet ideas or technologies or adhere to any specific ideology.  If we can approach the solution to this economic transportation problem from a different angle to obtain a more practical design that costs less and is easier to implement, then we're going to do it.

I would also like to point out, for those who may be interested (GW Johnson), that I'm not fixated on a counter-rotating habitat design, either.  If twirling the structure like a baton and using the Bigelow Aerospace inflatable module happens to be more practical, then so be it.  I proposed counter-rotation because of the inherent control and stability issues associated with a spinning top.  Counter-rotation was about counter-reacting and dampening mass distribution changes, nothing more.  Robert asserts that it's not a problem, but I disagree and would be willing to bet quite a bit of money that a physics professor will back up what I've stated.  I don't need a physics professor, though.  Drill a hole in the edge of a top, place a small weight there, spin it, and then watch what happens.  It's not stable and the amount of mass added doesn't have to be that significant, relative to the weight of the top.  I've already done that experiment as a child, so the results are already known to me.

Maybe that concept would be even more cost competitive since it uses well-developed inflatable habitat technology and does not require any newly designed and very strong central hub modules or electric motors.  We should do some trade studies to see what it entails.

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#67 2022-01-01 14:37:00

kbd512
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Re: A More Practical Interplanetary Colonization Ship

In case the point isn't perfectly clear, the primary issue with using Starship as an All-In-One transportation solution is that it's an upper rocket stage which must be exceptionally lightweight for performance reasons, it's sent to another planet for a minimum of 2 years, and then it has to come all the way back to Earth using chemical rocket engine propulsion.  Each Starship sent to Mars requires many thousands of tons of propellant in order to send 100 people on a 1-way trip to Mars.  That is clearly not sustainable over the long term, because almost everything you ship is propellant, rather than payload.  Each Mars-bound Starship must survive 2 reentry events and 4 main engine firing events prior to any refurbishment.  Effectively, Starships sent to Mars are not reusable and we're asking more of them than we ask of any other chemical rockets, reusable or otherwise.  I don't doubt that it can be done, but if you don't actually have to, then why bother?

We are trying to conceptualize a more mass-efficient alternative transportation system that leaves the interplanetary transport, whatever that ultimately looks like, in orbit around Earth or Mars, so that no reentry events or heat shielding mass are required.  Whatever we deliver to the surface of Mars, we want that to primarily be used for colonization.  To that end, we will use Starhip's stainless steel hull to create much smaller lander / habitation modules (permanent additions to the Mars colony) that will either have significant radiation shielding or will be partially buried to provide radiation shielding.  That involves providing a highly efficient power and propulsion scheme in Earth and Mars orbit, in order to minimize the mass of the transport ships and minimize propellant consumption, which drives launch rates and delivered tonnages to a far greater degree than the useful payload (the people and useful cargo used to build a Mars colony).

Please note that delivery of giant gas tanks and rocket engines or power generating equipment used to launch Starships back to Earth is not helping to build a Mars colony.  If you had excess power, then it would be more useful to devote it to building the colony, rather than producing LOX/LCH4 propellants.  We began launching giant chemical rockets here on Earth AFTER we developed the infrastructure for people to survive and thrive in a technologically advanced society, not concurrently or before-hand.  It's a manifestation of our successes, not the cause of it.

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#68 2022-01-01 14:52:11

SpaceNut
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Re: A More Practical Interplanetary Colonization Ship

From the "MagBeam satellites fire the plasma beam into the magnetic lens aboard the ship" question once the ship recedes from the manned ship we will begin to have issues that we are no longer able to feed power to the engines and that the satellite will fall quickly behind the ship. It appears that the satellites are not sent onto mars where they would be able to reduce the fuels required to get back home from mars to something more realistic.

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#69 2022-01-01 16:00:52

kbd512
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Re: A More Practical Interplanetary Colonization Ship

SpaceNut,

We're deliberately providing impulse bits to the ship when it passes close by the MagBeam satellite.  Let's say each satellite adds 0.1km/s of impulse to the outbound ship while it passes close by.  The fact that it passes out of range is not an issue.  You wait for another orbit, so that the MagBeam station has been recharged, and then deliver another 0.1km/s of impulse to the outbound ship.  If you do it that way, then the powered ships requires 30 orbits or passes at the MagBeam satellite to supply the 3km/s of Delta-V required to achieve escape velocity.  The orbit of the powered ship starts out being circular and then becomes progressively more elliptical with each impulse bit transferred by the MagBeam satellite.

The powered ship passes close to LEO and the MagBeam satellite once per orbit, at periapsis, and then the orbit extends further from Earth at apoapsis.  This is orbital mechanics 101 type stuff.  It's no different than firing the engines of a conventional chemical rocket at periapsis, and you could do the exact same thing with a conventional chemical rocket.  That is how satellites are put into transfer orbits from LEO to GEO.  The fact that we keep going over this point is a little baffling, since conventional communications satellites that place themselves into their final GEO orbits work the exact same way (fire thrusters at periapsis to add Delta-V, then stop firing, wait for another approach to periapsis during the next orbital period, rinse and repeat until the orbital altitude is modified, then fire again to circularize their orbits in GEO).  We're not trying to send anything to GEO, so we never circularize the orbit.

I already stated that we'd have a set of MagBeam satellites in LEO (Low Earth Orbit) and another set of MagBeam satellites in LMO (Low Mars Orbit).  We can also use whatever other orbits we require, in order to interact with the ships at the appropriate timings.  Orbital mechanics is GW Johnson territory, but I do know enough about operations to know that this is how we execute orbital transfers with all those satellites we put in GEO.  To my knowledge, there is nothing the least bit novel or controversial about this method of orbital modification.  We normally fire the engines 1 time for chemical rockets carrying people, in order to transit through the Van Allen belts as quickly as possible, but both satellites and properly shielded crewed spacecraft can use the method I proposed without issue, it simply takes more orbits to achieve escape velocity (two weeks for this method versus hours for chemical rockets following mere seconds of chemical engine firing).

The advantage is the 10,000s of specific impulse versus 450 seconds maximum for chemical or 1,000 to 5,000 seconds for arc jets or ion engines or electromagnetic thrusters like MPD or VASIMIR.  VASIMIR can achieve 10,000s Isp as well, but it also requires onboard power and propellant.  None of the power or propellant is stored aboard the powered ship or payload using the magnetized plasma beaming method, so it's even more efficient than any of those other methods.  It's not "spiraling out" the way any kind of ion engine would using continuous thrust, either.  Thrust is imparted at periapsis only.

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#70 2022-01-01 18:03:51

SpaceNut
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Re: A More Practical Interplanetary Colonization Ship

While in orbit trailing the ship the generating magbeam would with speed being picked up by the ship have pulses that get shorter and shorter in duration of receiving. That beam as it provides energy to the ship can make it dive towards the earth or make it rise in its orbit such that the effective energy is being consumed rather than being an extra shove to speed the ship up to escape speed.

Sure the ship will in a great number of passes get there but the beams will become less effective over time the beam will need to follow the ships arc as it trails.

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#71 2022-01-01 20:21:27

kbd512
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Re: A More Practical Interplanetary Colonization Ship

SpaceNut,

I'm going to attempt to respond to what I think you're getting at.  The orbital velocity of the powered ship increases due to the "gravitational slingshot effect" of an elliptical orbit.  In other words, velocity increases as the ship approaches periapsis and decreases as it moves toward apoapsis.  My argument is that we're talking about a relatively minor interaction time delta.  The ship's orbital velocity can never be equal to or greater than 11.186km/s, because that's escape velocity.  Recall that we're using a number of MagBeam satellites (32 satellites in total) and that the discharge rate of the batteries can be varied over time, within reason.  The initial interactions with the satellites will occur over a greater length of time, but then the discharge rate has to be increased to impart the same impulse bit over each interaction period.  You lose 30% of your interaction time between 7.8km/s and 11.186km/s.  That's significant, but it's not a show stopper.  We also have two opportunities to interact with the ship per orbital period, one as the ship approaches periapsis and the other as it moves away from periapsis.

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#72 2022-01-01 23:46:55

kbd512
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Registered: 2015-01-02
Posts: 5,730

Re: A More Practical Interplanetary Colonization Ship

If the MagBeam station interacts with the payload for 2 minutes, then...

At 7.8km/s the ship has moved 936km.

At 11km/s, the ship has moved 1,320km.

The original MagBeam concept intended to interact with a 10,000kg payload for 30 minutes in order to achieve escape velocity, whereupon it travels 14,040km at 7.8km/s or 19,800km at 11km/s.  Obviously the actual distance the payload moves in 30 minutes falls between 14,040km and 19,800km.  However, the engineers were confident that the beam coherence was adequate for that purpose, based upon lab experiment derived data related to beam coherence in a vacuum test chamber.

In my concept, I'm operating at a maximum of 1/15th of the distance from the MagBeam station that their 10,000kg payload would be at the end of a 30 minute firing sequence which ends with the 10t payload achieving escape velocity.  I feel that this is pretty conservative.

I stated that we needed a 4MWh battery aboard each MagBeam satellite, and that we would discharge to 50% capacity to conserve battery life.  I need someone who understands Lithium-ion batteries to help me understand the C rating on LiFePO4 cells and if 4MWh is sufficient capacity for a 2MWh discharge in 2 minutes, which equates to 16,666kWh / 16.6MWh per second.

I'm specifying PowerSonic 3.2V / 100AH LiFePO4 batteries, product code "SL-FP-IFP36130200EN", as my design reference cell.  It's a prismatic cell design that achieves 320Wh of total power storage, so I need a series of 12,500 of these cells per satellite and the total mass for all cells is 24,875kg.  If all 12,500 are run in series, then initial voltage is 40,000V and if I ask for a 30C discharge rate, that equates to a current of 3000 Amps.  Is that feasible or practical?  Can I discharge at that rate, down to 50% of cell capacity without substantially damaging the cells?

PSL-FP SERIES RECHARGEABLE LITHIUM IRON PHOSPHATE CELLS

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#73 2022-01-02 07:20:31

tahanson43206
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Registered: 2018-04-27
Posts: 10,438

Re: A More Practical Interplanetary Colonization Ship

For kbd512 re interesting design for acceleration using plasma ....

The only design for a receiver I have seen so far is a single loop of wire extended from a space craft.  There may well be other designs that are more capable that that, and which solve the problem of how to transfer force from the wire to the spacecraft.  If you know of such designs, please post a link.

A single thin wire loop would be able to transfer a few grams of force to a spacecraft in the rim, before the wire bent into a paperclip shape due to the force of the arriving plasma particles on the magnetic field, so your design must be far more robust.

In addition, the design you are referencing must consume far more power that the baseline design, because the loop must be able stop massive flows of particles as you've described in Post 72.

To my knowledge, there is no such thing as an "electromagnetic" funnel ... there **is** a magnetic field that can be generated by a current in a wire, and there is an "electrostatic" field that can be generated by loading a wire with electrons, or by removing electrons from a wire.

Thus, I am looking forward to learning about what an "electromagnetic funnel" might be, and where it is described in the literature.

(th)

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#74 2022-01-02 09:57:15

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 25,731

Re: A More Practical Interplanetary Colonization Ship

The magnetic force needs multiple turns under a high voltage low current design to create the field
Amp * turns = one Gauss (B) is equal to one Oersted (H) in air.

So a rigid 1 turn needs high amperage to create the same field strength.

There are many more equations to solve for the values but the concept of the field is to bring the diffused received plasma into focus for thrust out of the engine after reflection.

The magnetic field can be created in the shape of a funnel by placing larger diameter rings at different distances from each other.

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#75 2022-01-02 12:33:48

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,833
Website

Re: A More Practical Interplanetary Colonization Ship

Y'all are talking about propulsion techniques that I know nothing about.  Sorry,  I can be of no help there.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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