Large Ship Component Manufacture on Earth

tahanson43206 · 2024-11-20 18:08:03

For Void re #25

Please ** do ** continue your line of thought!

kbd512 has visions that differ from yours, and this topic is more than large enough for both of you .

There is ** no ** need for anyone to feel pressure to adjust their ideas based upon anything other than Ma Nature, who hands down decisions without partiality.

I personally ** like ** what I understand to be your idea, and I hope you will favor us (the forum plus non-member readers) with your vision of how your idea might be adopted by space architects.

I have adapted your idea slightly, and hope that my version of your idea might be given a bit of breathing room.

Ultimately, the ideas that are best are ** most ** likely to receive funding, and funding is the name of the game.

If your idea is most cost effective for building large structures in space, then it will receive funding.

(th)

Void · 2024-11-20 21:20:28

It is fine, I look forward to what the members do here. I do not want to be a problem of interference with it. I just wanted to make sure we understood each other's intentions.

Ending Pending

tahanson43206 · 2024-11-20 21:29:28

For Void ... the wording of post #27 seems to imply you will now abandon your idea before it has a chance to sprout, or whatever ideas do.

I hope you will give the idea some nourishment in another topic if not in this one.

(th)

Void · 2024-11-20 21:39:29

No, I have been addressing it in a collection of ideas here: https://newmars.com/forums/viewtopic.php?id=10867&p=2

I just am very interested in getting propellants from the metal of the ships, and then also as a side line structure as well.

The ideas I am working on are a bit too far removed from this topic.

Ending Pending

kbd512 · 2024-11-20 23:03:37

tahanson43206,

To be perfectly frank, Void's idea is something that should be pursued first, because if that actually works it means a very simple solution is at hand to travel between planets using bits and pieces of existing flight hardware. I'm not against Void's idea at all, because I don't care how this vehicle gets built as long as it actually works. I'm after the end result, not the aesthetics nor personal preferences. If lopping off the crew compartment of a Starship and welding it up to part of another vehicle actually works, I'll dance a jig over it and move on to the next interesting problem.

tahanson43206 · 2024-11-21 07:44:32

For kbd512 re #30

It appears that Void will be heading off to other topics, after dropping off the seed of an idea in this one.

I am reminded of Johnny Appleseed, who traveled around the newly formed United States of America to earn a living by distributing apple seeds.

In this case, the essence of the idea (as I understand it) is to send the second stage of a Starship launch up to LEO to be incorporated into a large structure in assembly there.

The second stage does not have to be round. Round is a logical shape for an enclosure for round tanks. However, the second stage could have walls that are flat. The design has to be strong enough to endure the forces of launch.

And if we grant that the walls could be flat, then it is a small leap to imagine walls that are gently curved to match the exterior of a gigantic Solar System vessel, such as the dual counter rotating habitat vessels described by kbd512 and GW Johnson elsewhere in the forum archive.

Thus, a single Starship designed for this purpose could deliver four panels for the wall of a Large Ship.

The tanks could be used as is for storage of liquids or gases in the large vessel.

What I'm looking for and hope will happen, is that one of the large vessel designers will tackle specification of components to be assembled on orbit to make a useful vessel for inter-planetary service.

Specifications would include (but not be limited to)...

1) Length
2) Width
3) Curvature
4) Thickness
5) Material
6) Mass
7) Specific assigned location on large vessel

At the moment all we have (that I have seen) is broad brush descriptions of large vessels.

Some of the work of RobertDyck can be interpreted as detailed, but we ran out of steam when we tried to imagine how to actually build the unitary rotating habitat design of RobertDyck.

My interpretation is that most of work done to build the single unitary design of RobertDyck could be adapted for the dual counter rotating designs of kbd512 and GW Johnson.

I note that the designs of kbd512 and GW Johnson are vastly different in size.

It seems likely to me that the smaller vessel would be attempted as a precursor for the gigantic one.

On the other hand, the methods developed to build the smaller vessel should be usable for construction of the large one.

What I'm looking for is a plan that could be implemented with funding.

What we have now are visions of what might be done, and those are essential, but by themselves they are insufficient.

(th)

Void · 2024-11-21 08:58:47

Well, I like this:

Four Starship Crew Compartments ganged together.

I am looking at nuclear electric propulsion with metal propellants, (Magdrive).

I don't like aerobraking to Mars myself, but each capsule might do it to aerobrake to orbit, but of course you would have to reverse the floor plan so to present convex to the atmosphere, and you would need a heat shield scheme.

The four sections could be reassembled after aerobraking.

For my part I am anticipating the use of nuclear electric (Jetson), with metal propellants, and perhaps the use of ballistic capture. And with no Aerobraking, the convex floors of the Crew Capsules will not be a problem.

Ending Pending

Jetson: https://www.space.com/space-nuclear-pow … in%20space.
Quote:

The U.S. Air Force Research Laboratory (AFRL) awarded $33.7 million to Lockheed Martin as part of the Joint Emergent Technology Supplying On-Orbit Nuclear (JETSON) effort to "mature high-power nuclear electric power and propulsion technologies and spacecraft design."
JETSON aims to launch a fission reactor that will be started up once in space.

It is possible that the tanks of the Starships might be converted to propellants. Then at Mars, you might get metals from Phobos or Deimos, should you want to return to Earth, or go somewhere else.

Ending Pending

Last edited by Void (2024-11-21 09:06:01)

kbd512 · 2024-11-21 10:12:07

tahanson43206,

We're definitely not "granting that the walls could be flat" if the interior of this flat-walled structure will also be pressurized. ALL propellant tanks are pressurized during launch, to something like 40psi to 70psi. As a function of basic engineering best practices, no part of a pressure vessel shall ever be "flat", because it concentrates stress into a very small area, which always leads to structural failures in real world pressure vessel designs. If you make said pressure vessel strong enough to temporarily overcome that stress / force concentration, then it's no longer a flight-weight aerospace structure.

GW can explain why we don't make pressure vessels flat, for like the 5th or 6th time that I'm aware of. This very idea has been proposed over again and again, and the response from the real aerospace engineer is always the same, each time it's proposed.

The following picture shows a single wedge / donut / section of the ITER Tokamak pressure vessel:
1-s2.0-S0920379616307244-gr1.jpg

1727190933948?e=2147483647&v=beta&t=FpPFSym1GKfacfGVkxtoOlHi2S5rbCpCMuEpDx6JXfo

1727190917974?e=2147483647&v=beta&t=r4NGNMMScMYUQ4HjGyv9dyUMCKFKUDyr6Umu4v2y0FE

Where the CAD picture is labeled "upper port" or "eq. port" or "lower port", pretend that doesn't exist, or that it's on the opposite side of the structure and pointed inward towards the center barrel section it's attached to. Pretend all the electromagnetic crap inside the pressure vessel doesn't exist, either. Roughly speaking, what you're left with is what a "slice" of the toroidal pressure vessel will look like. The dimensions will be different, wall thickness will be different, and the curvature of the vessel has to be different because it's much larger in diameter than ITER, but that's how the basic concept works.

ITER has an OD of 19.4m and it's 11.4m tall. It weighs 5,200t because it's trying to resist atmospheric pressure from the outside trying to crush it like an empty beer can. That wedge is actually hollow, meaning not a solid piece of steel, and IIRC, made from stainless steel. Coolant water is circulated inside of it to prevent it from melting. It can't be Mangalloy because it gets too hot and will be pressure cycled like crazy during testing.

We're shipping as many of these slices / wedges of the torus (the giant rotating donut) as will fit in the payload bay of a Starship per trip. They can either be bolted together if made from CMCs or they can be welded together if made from metals. If they have to be welded together, then they have to be fixtured in place during welding, and possibly heated up during the welding process using blankets.

tahanson43206 · 2024-11-21 10:35:11

For kbd512 re interesting mis-reading of text in post #33:

I said:

And if we grant that the walls could be flat, then it is a small leap to imagine walls that are gently curved to match the exterior of a gigantic Solar System vessel, such as the dual counter rotating habitat vessels described by kbd512 and GW Johnson elsewhere in the forum archive.

It is difficult for me to understand how someone could misread that, but obviously that happened.

The "flat walls" I was talking about were for the proposed Void concept of a Starship intended to deliver components; to LEO.

I have NO idea how that simple idea could have stimulated a rant about flat walls and 5 or 6 times ranting about flat walls.

However, that is clearly what happened.

The lesson is that English is a difficult language to master and obviously I am still a novice.

(th)

tahanson43206 · 2024-11-21 11:46:05

GW Johnson just sent me an email clarification of the design of Starship.

I've asked for permission to post the text, but a quick summary is that the hull ** is ** the tank, and not just a wind screen and structure component as I had thought.

This clarification means I'll have to change my understanding of Void's idea (again).

Aside from the misunderstanding of flat panels that occurred recently this new (to me) information from GW means that any panels that are carried aloft by a Starship as external elements would be released at LEO, and Starship could be returned to Earth as normal.

The curvature of such panels would be specified by the designer of the large structure. The curvature would be greater for a smaller Solar System vessel such as described by GW, and it would be less for a larger vessel, such as the Large Ship envisioned by RobertDyck.

(th)

Last edited by tahanson43206 (2024-11-21 11:47:01)

kbd512 · 2024-11-21 11:54:33

tahanson43206,

I'm completely willing to concede the point that rockets are very inconveniently shaped for transporting large and bulky cargo items. If we were able to ship the James Webb Space Telescope to orbit without all the origami work to package it into the cargo bay of a much smaller rocket, that would've made its design so much easier, faster, and cheaper. The aerodynamic drag and force exerted by pushing an object with the size and shape of a tennis court through the air made that idea a non-starter.

You cannot arbitrarily reshape the upper stage of a rocket powered vehicle because it's convenient for transporting an oversized piece of cargo to orbit. If the vehicle in question still has to store pressurized propellant and push through a dense atmosphere at supersonic to hypersonic speeds to reach orbit, then how it's sized and shaped must be optimized for that function.

If it was practical to assemble most of the counter-rotating vehicle here on the ground, fill it up with propellant, and launch it to orbit as a single-use upper stage (similar to the original Skylab concept which was ultimately abandoned by NASA), temporarily repurposing its interior volume as very large propellant storage tanks, then we would do that. Unfortunately, the forces exerted would also greatly exceed those which it would be subjected to on-orbit during the rest of its useful service life. That means it would have to be much stronger and therefore much heavier, in order to perform both missions.

That's why we're shipping it up in not-so-little pieces and assembling it after it's in space.

The vehicle I proposed has more than double the combined interior pressurized volume of a Starship and its Super Heavy booster, but its actual hull mass is LESS THAN the 375,000kg empty / dry mass of both of those rocket powered vehicles. The 9mD x 121mL Starship / Super Heavy vehicle would have 7,698m^3 of interior volume if it was a pure cylinder (no "pointy nose"). It's pressurized to about 60psi, IIRC, so the vehicle mass is clearly sufficient to contain that amount of internal pressurization load (hoop stress) trying to make it burst at the weld seams. The pair of torus structures in my proposed vehicle are 13,300m^3 in total. The connecting arms and center barrel section push total pressurized volume to greater than double that of an entire Starship Super Heavy launch vehicle. Somehow, my total hull structural mass is still 25,000kg lighter than a Starship Super Heavy!

How on Earth (or actually, how on-orbit) did I achieve that?

I started by using a steel 2X stronger than stainless, I subjected it to a mere 14.7psi of internal pressurization with a maximum overload of 22psi, and the forces acting on it is highly directional when the torus is rotating. The directional loads trying to pull the pieces apart while its spinning are resisted by both the shape and steel allocation (varying cross-sectional thickness), plus the fact that it's only subjected to 1g of acceleration when fully assembled.

How does that stack up to a Starship vehicle launch?

Starship is internally pressurized to about 60psi to begin the process of force-feeding propellants into its Raptor engines, and the vehicle acceleration is upwards of 3g after its drained most of its propellant, but the loads imparted to the vehicle are also highly directional in nature, so 375t of stainless is enough to ensure it doesn't disintegrate from the combination of internal pressurization, external aerodynamic loads, and thrust from the engines.

If you tried to do that with the assembled vehicle hull I proposed, it would burst after being internally pressurized to 3X its maximum overload. A strong gust of wind would act on sufficient surface area to topple the vehicle on the pad, whether empty or full, and it would also crush the booster beneath it from its weight when loaded with 50% more propellant to lift a 50% heavier (350t vs 200t) payload mass to orbit. The pad launch tower would need to be completely redesigned to accommodate a 50m diameter double toroidal upper stage. And the list of required changes to survive a launch goes on and on.

Can we still do that if we're really determined to?

I suppose we could, but every bit of the booster underneath it and the launch pad itself would require a complete redesign. Both the upper stage and the booster would need to be significantly stronger than they presently are.

That's why we're going to ship it to orbit in pieces small enough to fit inside Starship's payload bay, because we don't have to deal with any of those problems which would create significant additional work, slow progress, and become an impediment to building a practical large ship.

Void · 2024-11-21 16:22:56

Clarification for (th), again!

The diagram I gave was just a block diagram. Misunderstanding, is understood, as I did not give sufficient specifics.

The Bullet shaped objects in the diagram are imagined as Starship Moonships, with the propellant tanks cut off.

That bulkhead between the crew/passenger, quarters and the propellant tank is curved.

As I understand it those tanks are tested to up to 6 bars differential pressure. So, I anticipate that a pressure of 2/3 bar in the crew/passenger cabin could likely be tolerated in the reverse direction.

But we don't want two trains colliding, I am going to continue my version of things at "Index» Terraformation» Interworld Para Terraforming"

It's good!

Please see my next post after post #50. I am really pleased with what I think is possible.

Ending Pending

Last edited by Void (2024-11-21 16:29:04)

tahanson43206 · 2024-11-21 19:28:50

For Void ... thank you for continuing to think about your idea.... This topic is about manufacturing components for structures to be built in LEO.

Your contributions are welcome, even when they seem to be a bit off topic. They frequently contain ideas that are interesting.

I see delivery of components to LEO to be a key part of the manufacturing process.

We have a member who is currently advocating the open clamshell doors idea for Starship.

We have you, who originally appeared to advocate sending a Starship to LEO so it could be repurposed to make a large structure in space. Since that initial post it seems to me you have looked in other directions.

I am currently investigating the feasibility of sending components to LEO attached to the outside of Starships.; GW Johnson has corrected my misunderstanding of the design of Starships. Per GW, the hull of the Starships is also the wall of the propellant tanks.

I'd like to see this topic continue to grow in an orderly, focused manner, without excursions that belong in other topics.

If you (NewMars member) are designing a large structure to be assembled in LEO, then this topic is available to record your thoughts and to consider feedback from other members.

GW Johnson is (or was) working on a proposal for a counter-rotating dual habitat ship that would rotate at 4 RPM.

RobertDyck started us off with a vision of a Unitary Large Ship that rotates at 3 RPM.

kbd512 is (or was) thinking about a ship able to carry 500 passengers to Mars in a dual-counter-rotating design.

I'd like to see all three of these proposals in steady, incremental development.

(th)

Last edited by tahanson43206 (2024-11-21 19:30:57)

kbd512 · 2024-12-08 18:59:44

From another review of available documentation on the radiation environment posed by Earth's Van Allen Belts and random but potentially quite powerful Solar Particle Events, it would appear as though the non-rotating lander attached to the front of the Interplanetary Transport Vehicle (ITV) must serve as the radiation shelter. This implies the colonists' lander / lifeboat is the ITV's primary food and water storage container. There's no great issue with doing this, because any remaining food and water will be offloaded with the colonists when they separate from the ITV to make their descent to the surface of Mars, while the ITV continues to loop around on its free-return trajectory towards Earth.

I'm specifying the lander design from NASA's Manned Mars Mission Design Reference Architecture (DRA) 5.0:

The "triconic" reentry aeroshell depicted above is roughly 10m diameter and 30m in length. Reentry mass is 110,200kg. Landed payload mass is 40,400kg. My design would be lengthened to provide greater delivered payload, somewhere near 50,000kg. The major difference is that my lander facsimile will not use a split aeroshell design that splits apart during reentry, as depicted above, and it will be larger / heavier to accommodate a 50,000kg+ payload vs 40,400kg payload. It's a 125% landed payload scale-up of NASA's DRA 5.0 lander concept for the 500 colonists and residual supplies removed from the ITV. My variant of NASA's Mars Lander Vehicle (MLV) would remain intact through all phases of entry / descent / landing, a composite pressure vessel design wrapped in appropriate heat shielding materials to survive the reentry at Mars.

NASA's design specifies LOX/LCH4 engines, but to my knowledge small man-rated retro-rocket engines using that propellant combo don't exist, so perhaps LOX/RP1, which provides very similar Isp and better thrust, as well as having the benefit of being a fully developed propulsion system in active use, will be substituted instead. Some other design modifications may also be incorporated to produce a greater aerobraking effect, since this vehicle will be heavier and reenter at a higher interplanetary velocity, so braking aids such as the body fins used on Starship will likely be part of the MLV design.

RobertDyck · 2024-12-09 00:52:53

NASA DRM 3.0

tahanson43206 · 2024-12-09 07:22:23

This topic is intended to be about manufacture of components of large components of large space structures.

My hope is that a reader who starts at the top of the topic will find a set of related posts that build up knowledge about how this would be done, and specifically how those components would be delivered to LEO.

Such a reader would be treated to a preview of where all the effort is headed, with posts #39 and 40.

The suggestion offered earlier in this topic is to mount large panels on the exterior of Starship in such a way as to allow passage through the dense lower atmosphere.

I am hoping our members who are designing large vessels will give some thought to the possibility of fabricating large sections on Earth, and shipping them to orbit on the outside of Starship.

The alternative is what we see today. Components must be shipped to orbit inside the hull of ascent vehicles. In some cases, special oversized aeroshells are designed to enclose large objects for the trip through dense air.

In the absence of a large component delivery system, all components of a large structure must be fabricated on Earth so they will fit inside an ascent vehicles or it's aeroshells. This means that more components must be kept track of ahead of assembly, and all must be assembled by robotic remote control devices.

If we do not have a topic for mission architecture, it would appear we need one.

I'll take a look.

(th)

tahanson43206 · 2024-12-09 08:15:06

We have three members with large space vessel design projects in various stages of development.

RobertDyck is the most advanced, with over two years invested in a design for a Unitary Rotating Space Habitat with travel capability. If fully realized, this vessel would transport over 1000 passengers and crew. This vessel has a rotation rate of 3 RPM (20 seconds).

GW Johnson has described a smaller vessel with counter rotating habitats mounted on a common axle. This vessel is most likely to be built first because it is much smaller. This vessel would offer rotation at 4 RPM.

kbd512 has described a mid-sized vessel that would transport 500 passengers and crew. This vessel would provide counter-rotating habitats on a common axle.

In all these cases, this topic is available for creating a record of plans for fabrication of large components on Earth and transporting them to LEO for assembly there.

In order for this topic to be useful, it would be helpful for designers to provide drawings of components to be assembled on orbit.

When the component dimensions are known, it will be possible to attempt to find ways to deliver them to orbit.

An example of a component is a girder. All large structures are going to need girders to handle compression forces. Cables can handle tension forces, such as those exerted by air molecules at pressures sufficient to sustain human life.

Other components of interest for these vessels are panels. Most surfaces on these vessels will be curved, so the panels must be shaped on Earth to join with other similar panels to make the desired shape.

(th)

RobertDyck · 2024-12-09 15:17:55

I came up with a name for the first ship of the Large Ship class. On Earth the class is named for the first ship, so you could call it the Tiu class. I looked at a list of the word for Mars in various languages, and noticed the Old English. I speak English, and have English ancestry. My family is only traced back to the 1600s, but whatever, I like it. Alternate spelling is Tiw, because prior to the Roman invasion of Britain in the year 34 AD, English didn't have standard spelling. Not until much later. Alphabet for English prior to 34 AD was runes. Anglo-Saxon runes developed later, but prior to year 34 AD they used Elder Futhark. In fact, this is before the Angles or Saxons invaded Britain. In runes, Tiu is spelled ᛏᛁᚢ. That sort of looks the same, just with the "u" upside down. The problem with the alternate spelling, Tiw, is the rune for "w" doesn't look like a "w": ᛏᛁᚹ. So it's called Tiu, logo ᛏᛁᚢ

For the Tiu class, I envision construction in space. Harvest a metal asteroid in near Earth space. That means orbiting the Sun closer than Venus or Mars. Only 4% of asteroids are metal, but there are asteroids roughly 1 km diameter that are the same metal as a meteorite that falls to Earth. And meteorites are a reasonable sample to tell you what these objects are made of. They're mostly iron, with significant nickel, and trace metals of gold, silver, platinum, and platinum group metals. Purify the precious metals, bring them back to Earth. Keep the iron and nickel in space for construction of large objects: space stations or a Large Ship. Third most abundant metal is cobalt, also useful for alloys. These are true metal, not oxide ores, so a lot easier to process. But damn little chrome, and absolutely no aluminum.

Also mine the Moon. Surface of the Moon is mostly alumino-silicates. Anorthite is a common mineral on Earth's Moon Luna, and one company in Sweden is already mining and processing that mineral in their country to make aluminum metal. Use the same process on the Moon. Aluminum metal castings can be shipped to a ship yard in Earth orbit, as well as windows made of aluminum-oxynitride. That's aluminum oxide and aluminum nitride as powders, sintered to form a solid ceramic. Nitrogen shipped from Earth. The ceramic is transparent as glass, but a lot stronger. Used for windows of Abrams tanks, and windshield of some Hmmwv (Hummer) vehicles used in the Afghan war. Ideal for spacecraft windows, resistant to micrometeoroids.

This requires a steel rolling mill in Earth orbit, to make sheet metal. That will be cut, bent, and welded to form modules for the Large Ship. Also form pressure-tight doors. (3D printer?) Window frames for large windows will have to be made of metal at the rolling mill. Rubber seals shipped up from Earth.

Since assembly will be done in space, use electron beam welding, because that requires vacuum. Other forms of welding may have a cooling problem, but electron beam welding not only works in vacuum, it requires vacuum.

Life support equipment, machinery, and plumbing, wiring, electronics, photovoltaic panels (solar panels), and furniture all shipped up from Earth. They could be shipped in a SpaceX Starship.

The central zero-G hub is interesting. It could be made in space, or shipped from Earth. It would have the same diameter as a Starship, so the entire Starship cargo fairing could be the hub. The hub will have 3 spokes that connect to the ring of the Large Ship. The hub will also have cradles on the outside for space telescopes to attach, or detach when Large Ship is coasting. At least 2 space telescopes: one with a mirror as large as the Hubble Space Telescope but with modern image sensor and electronics. This would be for passengers to use; book time with a ship-board website. The second space telescope would be for navigation, acting as a stable non-spinning free-flying inertial platform for star sighting for precision guidance, as well as high resolution telescope to spot hazards such as uncharted asteroids or meteoroids. The hub would be as long as a Starship cargo fairing, but a cylinder all the way, not pointy on top. To streamline for launch, the hub would require a fairing to act as the nose cone, discarded during launch.

Aft of the zero-G hub will be a zero-G cargo hold for the Large Ship. This will also be the same diameter as a SpaceX Starship, so could be the cargo fairing of Starship. With interior rooms and cargo hold-downs. Also with a nose cone fairing, discarded during launch. The Large Ship cargo hold would be welded to the hub, not just docked. During acceleration and manoeuvring, thrust force will pass through the hull of the cargo hold, so it must be strongly attached. Pressure tight hatch from hub to cargo hold, so the cargo hold could be launched with that end open. Once it's welded, the aft bulkhead of the hub will act as common bulkhead between hub and cargo hold.

Aft of the cargo hold will be Control Moment Gyroscopes. These will orient the ship. This is a system used on ISS today. A heavy wheel is rotated in one direction, causing the station to rotate in the opposite. If the wheel is 1% the mass of the station, then increasing rotation 100 RPM will cause the station to rotate in the opposite direction 1 RPM. Slowing rotation of the wheel causes station rotation to slow. Stopping rotation of the wheel causes station rotation to stop. A set of 3 gyros set 90° to each other allows orientation in any direction. Increasing wheel speed allows reducing wheel mass. For large ship, these wheels will be big and heavy. The wheels will be cast in space, but the mounting frame and containing module could be launched by Starship.

Aft of the Gyro module will be the propulsion module. While the previous modules are welded together, the propulsion module will be docked. This will allow the propulsion module to be removed and replaced if new more advanced technology is developed. The propulsion module will consist of propellant tanks and engines, like any rocket booster stage. Again the same diameter as a SpaceX Starship. However, the propulsion stage may have to be much longer than a Starship cargo fairing.

RobertDyck · 2024-12-09 18:20:35

kbd512 · 2024-12-10 04:08:41

Looking back at the SSTO vehicle design I devised for reentry back at Earth, I think its airframe could pull double duty as a MLV design contender after appropriate retro-propulsion engines were installed. It doesn't require the same volume of fuel, so far more of its internal volume can become part of the crew cabin. The same qualities that made it a good vehicle for a quick trip to LEO would also make it good for a quick trip to the surface of Mars.

GW had devised an orbital space tug that uses chemical propulsion and novel halo orbits to enable transfer of up to 500 tons using a combination of chemical propulsion on the tug and electric propulsion on the ITV to complete the outbound orbital transfer, which greatly reduces the complexity and mass of the electric propulsion system aboard the ITV. As he explained during our last Sunday meeting, the ITV's Delta-V capability need only be around 600m/s to complete the transfer. That's well within the capability of a lower-powered Argon-fueled VASIMR to provide in a reasonable amount of time.

The major components to be manufactured are thus:

1X Central Node Module (CNM) - Connection Point for the Habitation Ring Modules, Lander / Lifeboat Module, and Propulsion Module
Primary structure will be welded Titanium forgings
Primary equipment includes the electric spin motors responsible for imparting rotation to the habitation rings
Secondary equipment will include the pipes and hoses supplying air and water to the habitation rings, pumped from individual storage bags retrieved from the LLM and connected to the CNM

The CNM is a pressurized / habitable microgravity space, similar in appearance to the spherical Russian ISS Node Modules, which provides primary shipboard control and access to all other parts of the ship. It's connected to the LLM (docked at the front of the ITV), PPM (rear of the ITV), and all 4 HRMs (X/Y plane vehicle attitude control; top / bottom / port / starboard HRMs).

Rather than building giant water storage tanks somewhere into the structure of the ITV, we will instead use the shipboard method of milk storage and distribution for a naval vessel's crew, which involves manhandling very large liquid-filled plastic bags, then connected to a self-contained distribution system, to supply the crew with their milk or orange juice. It would be very difficult to lose the entire potable or waste water supply using this system, because the water has been compartmentalized using hundreds of small plastic bags containing 5 to 10 gallons each. There's more packaging waste, but the bags are actually fairly light and compact relative to very large HDPE storage tanks.

If this seems like a very labor-intensive way of managing crew consumables, that's very intentional. I have 500 people confined aboard a ship in deep space for 6 months. I need to give everyone aboard that ship something to do with all that time. Maintaining positive control over strictly limited food and water supplies, with no possibility of resupply, is extremely important.

Beyond that, I don't have to design a highly integrated and appropriately protected and redundant centralized vehicle water management system. As required, crew consumables can be rearranged in the LLM to create a superb solar storm protection shelter to absorb highly energetic particles associated with radiation storms. If the crew's potable water supply is stored in individual 5 gallon plastic bags, then they have 5,000 individual water supplies. Using 10mil thick plastic, which is about 2X as thick as the plastic normally used to store milk in 5 gallon bags, total packaging weight for 25,000 gallons of water is about 662kg. If we wrap each bag in a thin layer of Nomex fabric to allow fast transfer of the water bags without too much concern over risk of damage, then perhaps double to triple that weight in terms of packaging. This is not a showstopper. The colonists still need containers to store things after they arrive.

4X Habitation Ring Module (HRM) - On-orbit assembled toroidal Titanium alloy structure
Primary structure will be welded Titanium plate with precision grinding and balance
Primary equipment will be berthing spaces for the crew and communal crew areas such as galleys, showers, toilets, laundry, and medical facilities
Secondary equipment will include shipboard damage control lockers with firefighting gear, mostly FFEs (fire resistant clothing worn by firefighters) and portable CO2 fire extinguishers
Tertiary equipment includes thin film photovoltaics wrapped around the hull of each HRM, to provide supplemental or backup electrical power

Each HRM is effectively its own limited-capability spacecraft, equivalent to an ISS module, albeit much larger.

1X Lander / Lifeboat Module (LLM) - All-composite construction high-speed reentry-capable lander, general purpose storage for crew consumables, and lifeboat if the HRMs become seriously damaged
Primary equipment is storage space for food, water, clothing, and other crew consumables
Secondary equipment includes space suits, spare parts, and can serve as a secondary ITV control center

1X ITV Power / Propulsion Module (PPM) - Solar thermal collector mirror arrays, supercritical CO2 or Argon or Xenon gas turbine, thermal regulation radiator arrays, VASIMR main engines, gyro stabilization system
Primarily composite structures, non-pressurized
Primary equipment provides ITV / shipboard services, to include power, propulsion, and pressurization

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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Re: Large Ship Component Manufacture on Earth

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