New Mars Forums

Official discussion forum of The Mars Society and MarsNews.com

You are not logged in.

Announcement

Announcement: As a reader of NewMars forum, we have opportunities for you to assist with technical discussions in several initiatives underway. NewMars needs volunteers with appropriate education, skills, talent, motivation and generosity of spirit as a highly valued member. Write to newmarsmember * gmail.com to tell us about your ability's to help contribute to NewMars and become a registered member.

#26 2021-12-28 00:06:57

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

SpaceNut,

The inflatable materials used in the TransHab and Bigelow Aerospace hulls is exactly what I had in mind.  It's legacy NASA / Bigelow Aerospace technology that has already been proven in space and requires no significant technological development or testing.  We already know that it works.  BEAM is still connected to ISS and Bigelow Aerospace inflatables have held pressure in space, despite MMOD hits, for many years.  The only real difference is that I want to use two inflatable torus modules 6.385m in (edit: radius, not diameter), with a 25m inner radius, and no hard center section module within the inflatable structure.  Each torus would be connected to a hard central hub / barrel section using a 3-spoke design.  I intend to use proven existing inflatable technology, rather than "reinventing the wheel".

The 25m radius happens to match up with this proposal:

Space Studies Institute - G-Lab 2017 Slides and Script

This is nothing more than a pair of counter-rotating Von Braun aritificial gravity space stations with appropriate propulsion elements included.

Slide14.jpg

I was unaware of SSI's G-Lab space station proposal before about an hour ago, which I found when trying to use Google to pin down masses for the BA330 whereupon I stumbled across their work, but I can see that engineers think alike.  Now that I know about this, I'm going to read through their proposal as well.  Since I am clearly not the first person to have this exact same idea, it's readily apparent that people with far more paper and aerospace engineering accomplishments behind their name than I will ever have, have all thought along the same lines.  Pretty much everything that I've thought was a great idea, if I search long enough, I find that someone else already had a very similar or the exact same idea.  There's very little that's "fundamentally new".  My design dimensions are slightly different because I was interested in achieving particular mass and volume targets to house 1,000 people and the underlying concept is nearly identical to what Robert proposed.

I am combining ET / M2P2 propulsion (de-facto active radiation shielding from solar protons, although that was not the original intent behind developing it, as it was intended to be a very high-Isp propulsion system capable of 50km/s to 80km/s velocities to explore the outer planets) with lightweight (relative to metal) fabrics-based pressurized habitation technology that happens to be more resistant to ionizing radiation and micro-meteoroid damage than metal.  The water walls were intended to provide additional radiation protection for women and children.  None of this is "revolutionary thinking", at least on my part.  It's combining a set of solid design concepts into a highly redundant and durable ship design that's capable of protecting large numbers of people for considerable lengths of time.

We're not sending old men and women because most of them can't work the same way that young men and women can.  Beyond that, no children equals no future, full stop.  It's a simple medical fact that younger men, women, and children are more delicate than middle-aged men and women past child-bearing age when it comes to radiation, so this design is deliberately choosing to protect them well enough that they can make the journey without undue risk.  It follows the ALARA principle, even if there's debate about how much damage is too much.  All of the materials are loaded with Hydrogen to stop protons / neutrons / electrons.  There's not much we can realistically do about the X-ray and gamma, but it's also far less of threat than the protons and relativistic protons which are highly energetic and damaging to DNA.

Last edited by kbd512 (2021-12-29 10:39:44)

Online

#27 2021-12-28 09:57:10

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,787

Re: A More Practical Interplanetary Colonization Ship

The linked page shows a dual launched Falcon 9 heavy that would trail the current ISS by 20 to 30 km which is indicated to be launchable on the Blue Origin New Glenn rocket as well.

It is setup for batton AG

Slide18.jpg

This is the inflatable no core
Slide19.jpg

Its a 2 rocket launch system to build
Slide20.jpg

final configuration
Slide21.jpg

So the hard sections which are the docking can be made from current Cynus construction and as KBD512 has indicated change the Beam physical characteristics to the desired to fit the length and we have most of what we would need. Life support can come from most recent ISS designs. Solar panels should not be a problem for a truss mounting.

This design should come in under a 2 billion dollar price tag.

Offline

#28 2021-12-28 15:18:27

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

This post will kick off life support power requirements for the ship.  We'll start with atmospheric circulation, move on to CO2 scrubbing, and finish with potential candidate technologies to supply the power required, which is considerable.  Discussion of IWP power requirements was not included, because it amounts to a few 10s of kilowatts for the entire crew.  I rounded up total power required to 1MWe, which covers all life support, avionics, and personal electronics.  That means 1kWh of power is provided for each crew member per day.  That figure does not include anything to do with propulsion.  About 800Wh is consumed providing atmospheric circulation / CO2 scrubbing / waste water reprocessing / active thermal control.  I expect personal electronics to consume 25Wh per day.  The rest of the power will be used for cooking and cleaning.  Waste heat will be dumped into the hot water supply and used to extract a little additional electrical power.

My calculation for required fan power to exchange the cabin air every 2 minutes is 96.14kWe using this fan model:

AirFlo Wet Environment Tube Axial Fan 60 inch 51000 CFM Belt Drive 3 Phase NBC60-J-3-T

Each of those not-so-little fans weighs 755lbs and we would need at least 22 of them, so 16,610lbs or 7,534kg.  If one of these units went down, it would be difficult to replace, not to mention difficult to maneuver into place for installation into the inflated habitation rings.

Then we have these much smaller and less obtrusive units from Amazon that only draw 95.32kWe at full output, but we need 686 units:

AC Infinity CLOUDLINE T12, Quiet 12” Inline Duct Fan with Temperature Humidity Controller - Ventilation Exhaust Fan for Heating Cooling Booster, Grow Tents, Hydroponics

The noise generated from these much smaller 12" diameter units is much less objectionable, though.  They can also control temperature and humidity for individual cabins, but weigh 15,544lbs / 7.05t (excludes the heavy ducting included).  The fan unit itself weighs about 20lbs, which is much easier to install and replace.  Though not by very much, we can economize on total volume / power / weight of installed equipment weight by going substantially smaller.  The individual fan units and ducting would be much lighter and easier to install and remove, though.  The reduction in space claim and generated noise is probably worth the additional wiring headaches.  We're going to need at least 1 spare unit for each ventilation circuit per ship, so 14.1t of installed air circulation equipment per ship.  Total cost for ventilation with the smaller fans would be $548.8K, less shipping.  I bet we get a volume discount from Amazon if we purchase 54,880 units for 40 ships. 

We already have a wiring nightmare to contend with to supply electrical power to all the compartments, as every ship does, so maybe this solution is not so bad.  The plastic does not appear to save much weight at all over the larger steel and Aluminum units, but those steel mounting brackets will not be used, and I bet that weighs 1 pound.  Overall, I like the lower power consumption of the smaller units but don't like the weight.  We should buy one to weigh the components to see if there are any heavy metal components that can be replaced.

We need to devote dramatically less power to Carbon Dioxide Removal, so:

eSionic Solid State Air Purification System

According to internet research (always a reliable source smile ), the average human exhales 2.3 pounds of CO2 per day, which works out to 23.712 moles per person, times 1,000 people, equals 23,712 moles per day.  The Solid State Air Purifier requires about 100kJ per mole to remove the CO2, so 2,371,200kJ, or about 659kWh per day.  The test results using the eSionic electrochemical membrane says 500kWh/day for 1,000 people, but I'm going with my worst case calculated figure to account for any control electronics requirements.

Based on fan power for acceptable circulation (1 complete air exchange every 2 minutes) and atmsopheric CO2 removal, we have a constant power requirement of approximately 754kWh/day for 1,000 people.  We could decrease the required fan power by half by making the habitation rings half as voluminous, but this buys very little to negate the constant power requirement.

A 35% efficient photovoltaic array therefore requires 1,584m^2 of surface area at 1AU to provide that kind of power, or roughly 39.8m by 39.8m.  At 1.5AU, or Mars orbit, you need 2,376m^2 of surface area, or roughly 48.75m by 48.75m.  That's pretty big, approximately 1/3rd of a soccer pitch, but still quite doable.  The ISS arrays cover 2,500m^2 for comparison purposes, but are very old / outdated and heavy for the power they provide.  Modern thin film array technology would require considerably more surface area, but the panels themselves would only weigh 2,000kg / 2t using current / actually flown in space by JAXA thin film photovoltaic technology.  The bottom line is that about 1MWe takes care of power required for habitation if thermal control is provided by water circulation and differential heating on the outside of the habitation rings (using water and white / black fabrics as a heat sink).

1,000 adult humans will generate between 100kWh (resting metabolic rate) and 300kWh (vigorous exercise) worth of waste heat per day, so we should look into harnessing some of that waste thermal energy rather than simply dumping it overboard, if only to further reduce power requirements.  I say we use it to power shipboard systems like avionics, gyros, and communications equipment.  Even if we can only recover 10% of that, it's an additional 10kWe.  It's a small amount of power relative to the total requirement to be sure, but it's something.

If you throw in supporting structures for the solar array, we're looking at 4t or less for a 1MWe thin film solar array, maybe 4.5t complete with CNT wiring. PMAD mass for the solar array is more difficult to estimate, because the voltages and amperages supplied affect the tonnage of equipment required.  We would likely use three-phase 440VAC and single-phase 120VAC for everything, so the equipment mass for that should be estimated.  Waste water reprocessing using IWP requires drastically less power than the atmospheric circulation fans and CO2 removal equipment.  A reactor core capable of supplying that much power would be approximately the same size as a 42 gallon oilfield barrel, although it would be exceptionally heavy if it required full core shielding, and it will.

If the photovoltaics are not desirable because huge arrays are too unwieldy for a maneuvering spacecraft to use during thrusting periods or damage-prone over time, then a deployable very large surface area fine wire mesh (thinner than a human hair), similar to or the exact same structure used by the electrodynamic tethers for orbit raising in the Van Allen belts, could deploy in deep space to directly collect electrical power from the Van Allen belts and the solar wind.  This would be as light as the thin film arrays, but cover an area measured in square kilometers.  The advantage over the much more compact (when deployed) photovoltaic array is that the wires are pulled taut (no inflatable or origami support structures are required) by the current flowing through it from the Earth's Van Allen belts or the solar wind, so it's not particularly sensitive to acceleration rates.  You can flex CNT wiring many millions of times while the craft moves around, and despite very high and very low temperatures, it remains very flexible and will not break.  Relative to any kind of solar array, it's nearly impossible to meaningfully damage.  The electrons from the Sun supply power directly to the spacecraft.

Online

#29 2021-12-28 18:24:54

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,787

Re: A More Practical Interplanetary Colonization Ship

I am aware of both technologies to part level and function.

Atmospheric co2 removal and air replenishment via vents, these are normally metal tubes that are in the 4 to 6 inch diameters and are located all over the place such as to keep co2 levels from becoming concentrated around the crews head. Which does not lend to an inflatable unit being sent up as complete as possible.

The inlet side needs the fan nearest to the opening as they would collapse if flexible tube is used if placed at the co2 processing location. Of course the system covers end to end for both aspects of processing and return. So keeping with the inflatable we need to design that system with flexible tubes something like used on a clothes dryer with fans being sized to the tube size used.

Water and waste can be so long as diameter is sufficient for either clear pvc tubing.

edit
https://www.nasa.gov/mission_pages/stat … l?#id=7635
Four Bed CO2 Scrubber is based heavily on the current International Space Station (ISS) Carbon Dioxide Removal Assembly (CDRA), which includes many design improvements based on lessons learned from nearly 20 years of CDRA on-orbit operations.

The ultimate performance goal is to remove 4.16 kg/day of CO2 at 2 mmHg inlet CO2. Another goal of the next generation CO2 removal system is continuous, failure-free operation for nearly 20,000 hours, but no complex life support system has yet reached this goal.

Offline

#30 2021-12-28 19:52:57

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

More on thermal control systems:

From a quick review of Boeing's External Active Thermal Control System (EATCS) for ISS, it appears as though considerable mass optimization on thermal control systems for satellites has been performed since that system was installed aboard ISS.

Study of the state of the art of Space Thermal Control Systems

This particular concept has merit for a drastic radiator panel weight reduction:

Microvascular Composite Radiators for Small Spacecraft Thermal Management Systems

Using the microvascular CFRP radiator panels, 407.6m^2 of radiator surface area are required to reject 300kW of waste heat supplied at a temperature of 25C / 77F.

Given that the atmosphere of the habitat module will have such a large thermal mass (33,281kg at 8psi), it's reasonable to think that the waste heat won't be supplied at temperatures much above room temperature, which means a very large radiator surface area.  The use of the microvascular concept really cuts down on radiator weight per square meter, as well as the mass of thermal power transfer fluid, in this case a 50/50 mix of water and ethylene glycol (basically, motor vehicle radiator fluid).  Other fluids with only slightly lower freezing temperatures, such as the polypropylene glycol "waterless" radiator fluid, would require a larger radiator surface area for no tangible benefit.

More on power systems:

After further consideration of the relative complexities imposed by deployment and protection of very large solar or CNT wire mesh arrays, I decided against both systems for providing life support power for my large ship concept.  The length of the solar panels was simply too great.  The lightweight panels seemed like a good idea until I calculated how stiff the support structure had to be.  It works for ISS because the station has exceptionally low acceleration loads placed upon it.

We're going to pursue using large numbers of Brayton-cycle Strontium Titanate Radioisotope Thermoelectric Generator.  Instead of using very low efficiency TEG semiconductors, we're going to dump that in favor of using direct thermal power to spin an electric generator using a Supercritical CO2 (sCO2) working fluid.  At 50% efficiency, we would require around 2,105kg of Strontium-90 to supply 1MWe.  If we account for the 50% decline in thermal power output over 28.8 years, then we actually need 3,158kg of Strontium-90 to maintain at least 1MWe over the ship's expected service life of 25 years.  Strontium Titanate (SrTiO3) is 5.11g/cm^3 / 5,110kg/m^3, so 0.618m^3 of active material.  These devices reach temperatures near 800C, which is above the 725C to 750C required by sCO2 gas turbines to produce 50% thermal-to-electric efficiency in a 2 stage design.  I'll have to do some more work to estimate shielding mass, but the shielding will be provided by Tungsten instead of Lead and steel.  That reduces the diameter required for effective gamma shielding.  That's hot enough that Inconel heat pipes and radiator panels will have to be used, because CO2 would corrode the hell out of most steels at that temperature.  In order to maximize redundancy we will use dozens of different isolated circuits.  We will provide complete heat source to electric generator to breaker to power conditioning to load isolation so that even a total failure of another circuit cannot completely degrade the ship's life support functions.

Online

#31 2021-12-28 20:25:36

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,787

Re: A More Practical Interplanetary Colonization Ship

https://www.nasa.gov/pdf/473486main_iss … erview.pdf
Active Thermal Control System (ATCS) Overview

Usually internal equipment is water cooled and that heat is what we are trying to remove.

Now if you are using the water walls then pumping that heat into them will aid in its removal.

https://technology.nasa.gov/patent/TOP2-291

https://ntrs.nasa.gov/api/citations/200 … 210002.pdf
Carbon Dioxide Removal Assemblies

https://blogs.esa.int/astronauts/2012/0 … and-still/

https://www.nasa.gov/sites/default/file … cation.pdf
Solid State Air Purification System

https://ntrs.nasa.gov/api/citations/201 … 017014.pdf
iss air ventilation system

Living Together in Space: The Design and Operation of the Life Support Systems on the International Space Station
https://spacecraft.ssl.umd.edu/academic … 206956.pdf

Offline

#32 2021-12-29 02:52:58

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

SpaceNut,

Yes, the water walls would be used to store heat and transfer waste heat into the coolant loops, as well as waste water processing.  I recently discovered highly thermally conductive polymers that do a good job of spreading out the heat, so perhaps we can use polymers instead of Aluminum as cold plates to reduce the amount of metal and mass within the habitation rings.  The extensive use of fibers / plastics / water is intended to absorb ionizing radiation from SPE / CME and to reduce secondary radiation showers created by GCR impacts on metals.  Thin metal hulls actually enhance the radiation dose received from GCR and does little to stop SPE / CME.

The grey water will be stored within special compartments and rubber bladder type storage tanks located adjacent to the bathroom compartments.  Whereas combat aircraft need self-sealing fuel tanks, this ship needs self-sealing sewage tanks.  NASA's water walls concept co-locates pouches of grey water within the areas where the astronauts work, sleep, and eat.  If a tank leaks, I don't think you want that anywhere near you, thus the special storage compartments.  Think of them as void spaces.  They're pressurized like every other part of the habitation rings, but isolated from the other compartments.  The same will be true of grey water discharge from the ship's galleys.  The water will be extracted and reused, with the food and fecal waste retained as fertilizer, as per Robert's original concept.

I've determined that my idea about using plastic center barrel sections is impractical because the plastic would have to be absurdly thick to resist the loads applied to it, so I've switched to steel.  The only candidates I have are 300 series stainless or 300 series maraging steel.

There will be three electric motors used.  The first motor is sandwiched between the "all-seeing eye" electro-optical sensor in the front of the ship and the first habitation ring.  This keeps the ship's primary navigation sensor stationary while the habitat module behind it is rotating.  The sensor is a very high resolution telescope to be used by the crew for both navigation and to serve as a display for crew and colonists who wish to see where they're headed to.  Tablets or communal VR goggles / glasses will be used to "see what the eye sees".  A set of distributed aperture sensors will display objects to the sides and rear of the ship.  There are no windows due to the cost / complexity / vulnerability they represent, so this is your view of the outside world without going on a space walk.  The second motor is located between the first and second habitation rings to counter-rotate the second habitation ring.  The third motor is situated between the second habitation ring and power / propulsion module of the ship.

Speaking of power and propulsion, this module will also be 300 series stainless to contend with the heat of the RTG cores.  Further aft of the RTGs there will be reels for the electrodynamic tethers, storage tanks for O2 / N2 / CO2 / Ar / CH4, and gyros to control the attitude of the ship.

More on food:

Using heavily packaged freeze-dried foods to provide 2,000 calories per person per day for 2 years would only weigh 425t, not 730t.

Legacy Food Storage - 1,108lbs of Freeze Dried Food

1,000 people * 2,000 calories per person * 730 days = 1,460,000,000 calories

1,460,000,000 calories / 1,726,560 calories per 1,108lbs of food = 846 freeze dried food kits * 36 buckets = 30,456 buckets of food

1,108lbs per kit * 846 kits = 937,368lbs / 425.3t of food including all packaging

57.19ft^3 per kit * 846kits = 48,382.74ft^3 / 1,370m^3 (approximately 11.1m x 11.1m x 11.1m)

The food, water, passengers will easily fit within the habitation ring.  I'm starting to think that 6.385m diameter is too much.  It adds too much weight and only some of the compartments can be fully shielded by the water wall.  Perhaps it's time to downsize the habitation rings.

We have some pretty crazy hull mass figures, not to mention atmospheric mass and circulation power requirements driven by giving the crew 50m^3 of pressurized volume when all of NASA's studies showed greatly diminishing returns past 25m^3.  This ship is mostly empty space and not enough radiation shielding because the water would weigh too much.  We could downsize to 25m^3 of pressurized volume per person and then our hull mass is 187.5t.  At 8psi, we have a test-backed safety factor on the hull of around 7.5.

Revised Mass Table
1,000 Crew and Personal Belongings (at 100kg per person): 100t
Hull: 187.5t for both inflatable habitation rings for 25m^3 of pressurized volume per person
Food: 425t for 730 days of food
Water: 250t
Electro-Optical Sensor / Telescope Module: 10t
Hub / Barrel Section: 100t (50t per hub module)
Sr90 RTG-Based Power Module: 75t (just a guess at this point)
Propulsion Module: ???
Propellant: ???
Habitation Ring Atmospheric Mass: 16.6t at 8psi
Electric Motors for Counter-Rotation: 7.5t for all 3
Atmospheric Circulation Fans: 3.5t and half as much electrical power

At perhaps 1,250t, less propellant, this is starting to look a little more practical.  I went back and re-read some of the documents provided by Winglee.  I thought we couldn't use M2P2 within a magnetosphere, but apparently we can, which means electrodynamic tethers are not required.  MagBeam would still be very useful, if available, for a swift transit through the Van Allen belts.  Anyway, little by little we're starting to identify dead end ideas and remove unnecessary system mass, bringing the power and propulsion requirements into the realm of feasibility.

Online

#33 2021-12-29 03:24:25

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

I almost forgot, but the revised torus dimensions are as follows:

25m: inner radius
34.25m: outer radius
4.625m: tube radius
29.625m: radius of revolution
12,509m^3: volume of torus

That's still slightly wider than a Starship's 9m diameter propellant tank when inflated.  There's still no ability to fully shield the interior with 20cm of water...  I think a compromise between habitable volume and shielded volume will have to be made.

Online

#34 2021-12-29 09:55:44

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,952
Website

Re: A More Practical Interplanetary Colonization Ship

Water is not the only low atomic weight-containing material that could serve as shielding.  The Bigelow B330 design had almost a meter of layers of fabric materials for insulation and meteor protection,  that also was quite effective as radiation shielding against the low-energy solar flare particles.  That's twice the thickness that is on the BEAM module at ISS,  where the threat is half of that in deep space.

Just food for thought.  I rather liked the Bigelow designs,  and am sorry to see them go.

GW


GW Johnson
McGregor,  Texas

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

Offline

#35 2021-12-29 13:08:16

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

GW,

I agree, but the radiation protection provided remains insufficient.  You need that 20cm of water, or you don't have a usable ship if it has to spend a week to a month inside the Van Allen belts during the orbital transfer phases of flight (outbound to Mars and inbound to Earth).  That means 25,018m^3 is still way too much internal volume.  Internal volume that you can shield in a practical manner using what you must take with you to keep everyone alive appears to be what imposes the practical upper limit on the ship's crew size.  Try to carry too many people and you end up adding unnecessary mass that detracts from the practicality of the ship.

If you try to transport 1,000 colonists per flight, then you need a ship so large that it can't be adequately shielded against radiation.  You also have this unnecessary operational limitation wherein you require 2 Starship crew transfer flights because 1 Starship can hold a maximum of 500 people per flight in "airliner mode".  That means 500 colonists must wait for the other 500 to arrive.  That inevitably means delays and burning through consumables.

I base the 25m^3 design requirement on this and other supporting documents from NASA for the expected trip duration:

Factors Impacting Habitable Volume Requirements for Long Duration Missions

Flip to page / slide 3 of the document for the graph of trip duration versus habitable volume.  There are other documents from NASA detailing why 25m^3 was selected as optimal for 300+ day missions.  Anything beyond that was nice to have, but added very little to the experience.  I've posted those supporting documents in other threads.  This was discussed before the large ship concepts arrived.

More downsizing to transport 500 colonists per flight to align with Starship's passenger transport capabilities:

25m: inner radius
31.7m: outer radius
3.35m: tube radius
28.35m: radius of revolution
6,280m^3: volume of torus
12,560m^3: total pressurized volume

To get 20cm of complete coverage inside the habitation rings, 2,888m^3 of volume must be filled with food or water.  With 250t of water (250m^3) and 212.5t of food (685m^3), I only have 935m^3 of consumables volume to work with which means I'm a factor of 3 short.  If I reduced the water volume to account for the fact that half as many people are onboard, then I'd be shorter still.  Even with a pair of 7m diameter / 3.35m radius habitation rings, we can't begin to fill the spaces with enough Hydrogen rich materials.  Bigelow Aerospace's BA2100 "Olympus" inflatable modules were to contain 2,250m^3 of pressurized internal volume.  This vehicle's habitation rings contain 5.5X as much internal volume.

To actually get 20cm of shielding for at least the start of the mission, these are the habitation ring dimensions:

25m: inner radius
30.5m: outer radius
2.75m: tube radius (almost identical to a Boeing 787 fuselage)
27.75m: radius of revolution
4,142.5m^3: volume of torus
8,285m^3: total pressurized volume (54X Boeing 787 cabin volume)
16.57m^3: total pressurized volume per person with 500 crew members
7,350m^3: total pressurized volume minus consumables volume (48X Boeing 787 cabin volume)
14.7m^3: total pressurized volume per person with 500 crew members after subtracting consumables volume
31,068.75kg: Hull mass per habitation ring
62,137.5kg: Total habitation ring mass
5,510kg: Total atmospheric mass at 8psi

Now we're moving back into the realm of practical engineering.  We need half as much life support power, our atmospheric circulation power goes down by a lot, and the total mass of the ship, less propellant, is now 1/2 the mass of the ISS.  We can feasibly send that to Mars using chemical propulsion, although it still doesn't make any sense from a cost perspective.

Online

#36 2021-12-29 14:19:53

Quaoar
Member
Registered: 2013-12-13
Posts: 644

Re: A More Practical Interplanetary Colonization Ship

GW Johnson wrote:

Just food for thought.  I rather liked the Bigelow designs,  and am sorry to see them go.

GW

Hi, GW

I heard Bigelow had some trouble during pandemic. Do you think they will not survive?

Offline

#37 2021-12-29 15:59:49

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,952
Website

Re: A More Practical Interplanetary Colonization Ship

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

Last edited by GW Johnson (2021-12-29 16:00:27)


GW Johnson
McGregor,  Texas

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

Offline

#38 2021-12-29 16:48:13

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,787

Re: A More Practical Interplanetary Colonization Ship

Lets kind of put that 25 cubic meters into prospective as to what that means for a crew person. It is the space were you do not feel crowded in with its surroundings and others moving with in that area. This is your area to eat, sleep and work within ect.

https://en.wikipedia.org/wiki/Assembly_ … ce_Station

Pressurized Module Length: 218 feet along the major axis (67 meters)
Habitable Volume: 13,696 cubic feet (388 cubic meters) not including visiting vehicles
Pressurized Volume: 32,333 cubic feet (916 cubic meters)
With BEAM expanded: 32,898 cubic feet (932 cubic meters)

https://www.nasa.gov/pdf/179225main_ISS_Poster_Back.pdf

Offline

#39 2021-12-29 19:24:30

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

I started thinking about the interior configuration required to adequately shield at least parts of the ship, and it occurred to me that if only the sleeping quarters and a central passageway running through the habitation ring were lined with the water bags, then there's adequate water volume to shield those areas of the ship.

It's hard to express how significant the pressurized volume of the ship is at 8,285m^3, but ISS is 915.6m^3 for reference.  If Bigelow Aerospace had built their proposed BA-2100 modules with its 2,250m^3 of pressurized volume, then this ship's interior would be 3.22X larger after all of the consumables were loaded.  That does not account for the pressurized volume of the spokes or central hub modules, either.  An Olympic swimming pool's minimum volume is specified as 2,500m^3 for comparison purposes.  The outer diameter of this ship's pair of inflated habitation rings measures 61m.  SpaceX's Starship is 50m, so it would fit tip-to-tail inside the inner radius of the habitation ring.

This reminds me that we still have not discussed crew transfer to the ship.  To embark colonists, the habitation rings need to spin down, and then the arriving Starship needs to perform a maneuver similar to what the Space Shuttle did when it docked with ISS.

Online

#40 2021-12-29 20:02:29

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

SpaceNut,

A mere 25m^3 can't be properly shielded using 2 years worth of provisions.  The ship ends up being a lot of empty space with nothing to put there.  After the volume of provisions is accounted for, the only other spaces are either berthing compartments or communal areas such as messes / galleys / showers / toilets.  There are no scientific instruments and the cargo is delivered by separate ships.  The maze of wiring, computers, and science experiments aboard ISS aren't present here.  Take all that stuff out of ISS and you're left with the world's most expensive wind tunnel for 3 to 6 people, because it's equivalent to 6 Boeing 787s.  Imagine being the only passenger aboard a 787.  To merely achieve adequate shielding, we're not shielding any of the communal areas except the toilets.

Effectively, each person aboard this ship is allocated a volumetric area slightly greater than the BEAM module attached to ISS.  Sure, you'll see the other people aboard ship all the time, but that is normal for sailors and will become normal for colonists.  Everything you own fits in a duffel bag and your beds are fold out air mattresses.  All chairs are of the blow-up variety to conserve mass / decrease volume when transported / not become an obstacle or trip hazard.  There's simply nothing left to fill this ship with.  It's colonists / food / water / a few toiletries and personal electronics, but not much of anything else because nothing else is going.  As a colonist, you just sold all of your personal belongings on Earth to purchase your ticket and you're starting over from scratch on another planet, with a local company providing all housing / consumables / tools to their employees as part of a package deal.  Homesteaders didn't have a bunch of personal effects because they were far too busy building / farming / trying to survive.

I know this seems like a very spartan existence to many here, but nothing I've acquired before / during / after my military service ever made me happy.  My wife and children make me happy.  Building things with my own two hands makes me happy.  All the stuff I've acquired over the years is baggage, and every time I have to move I'm reminded of how much money was spent and how little utility most of that stuff actually provided.  Apart from tools to repair things that are broken, food, and a new (15 year old) car to drive to work, I haven't purchased anything of a personal nature in the past several years.  Look around you and ask yourself what you could live without.

Online

#41 2021-12-29 21:00:55

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,787

Re: A More Practical Interplanetary Colonization Ship

I have cdroms music, DVD's to watch and listen to with portable devices as I do not have the best of computers to have all of that stuff digitized other wise I own nothing more than you do for a car to go to work and the tools to repair it.

That said a beam could hold 30 people no problem so why so large as that is why we are having issues for design. Plus with all of the common area in the other things that you need to have to cook and eat food.. or is it just the shape to gain AG which is causing the problems?

The rise and fall of artificial gravity So, why has no one built one?

p0140xss.webp

You will have logistics making use of computers to track the peoples health during the journey, keep track of food usage, waste stream so we will need plenty of them for use.

There is still ongoing science its just not the R&D type, star gazing, monitoring ships conditions.

Even thou we have a safe ship we want everyone to have a space suit and life support for it to be of use just in case.

http://spacearchitect.org/pubs/ESA-WPP-200.pdf
Modular Inflatable Space Habitats

Offline

#42 2021-12-30 00:49:34

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

SpaceNut,

Nobody has built an artificial gravity habitat because Congress took the inflatable habitat technology away from NASA the very moment they realized it could be used to go to Mars.  In the Boondoggle Era, the end goal of our manned space program is to spend money for sake of spending money.  Both Congress and the Executive view NASA as a workfare program for their highly educated constituents, and a slush fund for the defense contractors who funded their election campaigns.  NASA ceased to have a manned space exploration program before I was born.  If NASA does any actual space exploration with men and women aboard, it's a freak accident that needs to be remedied with appropriate funding cuts to ensure that nothing like that ever happens again.

A decade after retiring the Space Shuttle NASA now has capsules that can be used to transport humans to the ISS thanks to SpaceX, but if it relied upon our defense contractors then the US would still have no capability to launch humans into space.  Boeing built the first stage of Saturn V for the Apollo Program, but now it can't figure out how to put another capsule into space and has no clue what went wrong with the one they accidentally successfully launched into space.  Boeing can't seem to get SLS off the ground, either.  Somehow the "proven hardware" from the Space Shuttle Program, that was supposed to be "cheaper and better" than simply rebuilding the Saturn V, has been in development for longer than the Saturn V program ever existed, from cocktail napkin stump speech in President Kennedy's head to last launch.

SpaceX could've already done another "flags and footprints" mission to the moon using Falcon Heavy and a pair of Dragon capsules.  The entire benefit of a "flags and footprints" mission would've been actually putting someone else on the moon.  Somehow a guy who started a rocket company on a dare has a fully reusable super heavy lift launch rocket sitting on a pad in Boca Chica, waiting for the federal government to finish goofing off with the launch permit, in less time than it took for Lockheed-Martin to figure out how to fix the cracks in Orion's pressure vessel, despite building pressure vessels for spacecraft since before Elon Musk was born.  If anyone thinks the problem is with the technology, think again.  It's a people and motivation problem, plain and simple.

Online

#43 2021-12-30 02:45:45

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

More updates on propulsion:

If we use MagBeam propulsion on both ends, then we may not require much from M2P2 and can eliminate the Electrodynamic Tethers.  The ship only requires small onboard thrusters for mid-course corrections and gyros to control its orientation.  The "magic" of MagBeam is that it supplies both the propellant and the power to turn the propellant into thrust.  The MagBeam station creates a tightly focused magnetized beam of plasma that's reflected off the rear of the spacecraft it's accelerating or decelerating.  Moreover, these are impulsive maneuvers that take place over minutes to hours.  For some reason, I hadn't realized that MagBeam's propellant is actually stored onboard the MagBeam orbital station, not aboard the payload it's imparting thrust to.  This drastically simplifies the propulsion problem, because now the ship is nearly 100% payload.  That means the ship does not require any significant onboard propellant supply.

From recent estimations, the all-up weight of this drastically scaled down interplanetary transport will be near 750t, maybe a bit less.

To accelerate a payload from LEO to escape velocity in 30 minutes, MagBeam requires very high power output of 8MWh per ton of payload, but that is doable using existing batteries and fuel cells.  MagBeam therefore requires 6GWh of power output to accelerate this ship to escape velocity.  Hydrogen provides 23.52kWh/kg in a 70% efficient regenerative fuel cell, which means 255,102kg of H2 is required.  The SLS core stage stores 730,000 gallons / 195,567kg of LH2 for comparison purposes.

At this point, I know what everybody is thinking- that's an absolutely absurd amount of power to supply.  There's no way.  Over a time span of 30 minutes I would tend to agree.  However, there's a fortuitous catch.  We don't have to supply that much power merely to make the orbital transfer maneuver occur within a time frame of 30 minutes.  The impulse can be supplied to the payload (the 750t ship) in impulse bits.  There's no need to orbit an entire SLS core stage and its propellant supply to do this.  That's a very good thing, because I doubt that would be very practical.

Instead of that nonsense, we're going to use a series of much smaller and lighter MagBeam stations equipped with solar panels and batteries, and over time, we will propel the ships using impulse bits.

We need a series of solar power satellites equipped with 4MW solar arrays.  Assuming a 35% efficient solar array, the array area will be 100m by 100m to supply 48MWh worth of power per day, stored in batteries for discharge.  We will eventually require a series of 32 stations to maintain a launch rate of 80 ships per year to transport 1,000,000 colonists to Mars over 25 years.  However, we will initially only need 8 stations to launch the first ships over periods of 16 days.

With a specific impulse near 10,000seconds, a modest 25,000kg / 25t of Hydrogen is required.  This is split between the 8 stations, so 3,125kg per MagBeam station.  Over the course of a single orbit, the 4MW solar array will collect 3MWh worth of power in 45 minutes.  If we assume an all-up battery pack weight of 200Wh/kg, then we need 15,000kg of batteries at 100% Depth-of-Discharge (DoD), or 30,000kg at a 50% DoD to improve the battery service life.  If we presume the photovoltaics achieve 250W/kg, then the solar array weighs 16,000kg.  I expect all-up spacecraft weight to be somewhere near 75t after structures, radiators, reaction control system, and all other subsystems are included.

These spacecraft do require a maintenance activity between ship transfers to refill them with LH2 propellant, but we're talking about 25t of LH2 propellant split between 8 MagBeam orbital stations.  That's a minor logistical burden when compared to supplying 6GWh of power onboard the ship, plus the propellant.  All propellant is expended (fired as a coherent beam of magnetized plasma at the interplanetary transport ship and reacted off an electromagnetic "plate" affixed to the rear of the ship, in order to propel it to escape velocity) over the course of 16 days.  Every MagBeam station interacts with the ship for a matter of minutes when the ship approaches the station, then recharges its batteries in preparation for the next "shot" at the ship.  The ship's velocity gradually increases as impulse bits are imparted to it, until it eventually achieves escape velocity.

Thereafter, minor course corrections are applied in deep space until the ship approaches Mars, where the same process is repeated in reverse.  The stations located in Mars orbit can use Argon or Carbon Dioxide, although specific impulse suffers a bit from the decreased velocity achievable with heavier gas molecules.  That is a less serious problem than keeping Mars-based MagBeam orbital stations supplied with propellants, thus the idea that we collect CO2 from the upper atmosphere of Mars.

Online

#44 2021-12-30 05:44:17

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 2,223

Re: A More Practical Interplanetary Colonization Ship

MagBeam is an interesting idea.  A MagBeam accelerator would need to be located in high Earth orbit, otherwise the ions would be deflected by Earth's magnetic field.  But field strength follows the inverse square law.  So at the moon's distance from Earth, it would be 1000x weaker than it is at LEO.  As Mars does not have a magnetic field, accelerators could be located anywhere in orbit.

Last edited by Calliban (2021-12-30 05:47:56)


"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."

Offline

#45 2021-12-30 08:27:26

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 12,048

Re: A More Practical Interplanetary Colonization Ship

For kbd512 re MagBeam idea ... this method seems (to me at least) to compare favorably to the "traditional" concept of using a laser (or several lasers) to accelerate a ship that has deployed a solar sail.

The mass of the ions is significantly greater, although their velocity is significantly less.

Just out of curiosity (since this is the first I've hear of the MagBeam idea) .... could a traditional solar sail work for ion momentum transfer to the vessel?

If it can, then you could combine MagBeam with photon beam acceleration to improve system performance.

(th)

Offline

#46 2021-12-30 10:36:03

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,787

Re: A More Practical Interplanetary Colonization Ship

So no AG just fast transit using post 27 image for shape of vehicle or is there another shape.

A sail would need to be deployed after the initial earth departure escape and we are now ready for coasting.

So is the MagBeam a power source that is beamed to a receiver that is connected to the ship to cause the mass to not be part of the ship?

Offline

#47 2021-12-30 11:07:51

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 2,223

Re: A More Practical Interplanetary Colonization Ship

I am assuming here that a MagBeam is a neutral plasma, accelerated by electric fields in a perpendicular magnetic field.  Or is it positively charged particles accelerated by an oscillating electric field?  Either way, I think beam coherence is going to be a problem.  The plasma will spread out at an angle from the exit aperture of the accelerator.  The motion of the particles is not coherent - the particles will have perpendicular velocity to the direction along which they are accelerated.  They will spread out over distance due to their own motion, as well as being influenced by external electric and magnetic fields.

What this means in plain English is that the MagBeam has a very limited effective range.  You would need to load the ship onto the end of the particle accelerator and propel it like a bullet from a gun.  The acceleration would fall off with increasing distance.


"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."

Offline

#48 2021-12-30 11:17:00

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,787

Re: A More Practical Interplanetary Colonization Ship

So much like the microwave oven the magnatron needs a ring or field magnet to control the beam spread.

Offline

#49 2021-12-30 12:52:57

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,238

Re: A More Practical Interplanetary Colonization Ship

Calliban,

Perhaps these documents will better explain what MagBeam is and isn't, and how it would be used:

Beam Propulsion by Chuck Vaughn

MagBeam by R. Winglee, T. Ziemba, J. Prager, B. Roberson, J Carscadden

Edit:

Due to orbital mechanics and the altitude above Earth where the Van Allen belt radiation is most intense, no these MagBeam satellites will be located in LEO, not in a high orbit.

Last edited by kbd512 (2021-12-30 12:59:43)

Online

#50 2021-12-30 18:11:40

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,787

Re: A More Practical Interplanetary Colonization Ship

The beamed energy can come from the constellation of starlink satellites turning to face the receiver to send the power to the ship while building up charge to be used.

Offline

Board footer

Powered by FluxBB