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#876 2021-10-11 09:47:44

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

Well, preparing PowerPoint slides. Needed a complete model as a graphic. Mars Society virtual convention starts this Thursday. I'm scheduled to speak: Saturday @ 4:00pm Pacific Time (6:00pm Central Time) on St. John's Newfoundland. And the same day @ 5:00pm Pacific time (7:00pm Central Time) on Large Scale Colonization Ship. Each presentation is supposed to be 25 minutes plus 5 minutes for questions.

Traditionally the convention has a formal banquet on Saturday. Unfortunately food for this year's banquet is limited: only what you have in your kitchen. wink But this year's convention packed! Saturday there's only ½ hour break for supper, then more programming. Normally there was little Sunday morning, with the convention closing shortly after noon. This year is packed to late Sunday. And Thursday morning is packed too.

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#877 2021-10-11 11:13:23

tahanson43206
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Registered: 2018-04-27
Posts: 8,012

Re: Large scale colonization ship

For RobertDyck re #876

Congratulations on landing a slot (two slots) for the Convention.

I sent a copy of #876 to my contact at the North Houston NSS chapter. 

Hopefully they'll decide to forward the announcement, but I have no idea if that is part of their procedures.

One option is for the link to the video recording to be made available to their members at the next meeting on the first Saturday in November.

That would give you some exposure.

We (NewMars) have a standing invitation to make a presentation to NH-NSS, so your initiative here might lead to an opportunity there if you are interested.

They are a friendly audience.

(th)

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#878 2021-10-13 17:10:07

kbd512
Administrator
Registered: 2015-01-02
Posts: 4,895

Re: Large scale colonization ship

RobertDyck,

Looks good.  I still like the counter-rotating habitation ring concept to counteract gyroscopic precession so thrusting does not require spin-down or significant gimbal of the thrusters, but whatever.  If it works, it works.  I still think the so-called "Dzhanibekov effect" will cause this thing to periodically flip end-over-end and fail to see how such would not be the case, or how your design, as shown, will not have an intermediate axis for torque to act upon.  If it's strong enough, then maybe the ship will be fine, but if the humans inside it are thrown around, then that won't work.  I think your basic design is fine, but with 2 habitation rings spinning in opposite directions using a single very large electric motor between them to accelerate both habitation rings in opposite directions to the same velocity, will provide the best assurance of trouble-free operation.

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#879 2021-10-13 17:56:36

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 8,012

Re: Large scale colonization ship

For kbd512 re #878

Thanks for the reminder of the benefits of the counter-rotating system.

RobertDyck has been consistent from the beginning of this topic, in resisting the complication of ball bearings needed for any counter rotating system.

That is why I would like to see a space demonstration of a small model of his design.  A good 3D modeling language with a physics subsystem might be able to simulate the device.  RobertDyck is gaining ground in learning Blender, but that is a very sophisticated package, and it will take a while to learn how to generate motion, let alone use the physics module effectively.

I wish we had members who were interested in 3D animation, because modeling the Large Ship physics would (surely) be an interesting challenge.

There ** is ** an alternative between the the two of you, but knowing how resistant RobertDyck is to anything that departs from his vision, I only toss it out for the record.

The core cylinder ** could ** include a counter rotating mass at some suitable location along it's length.

That mass would ** not ** be a habitat, but it could include supplies for the flight.

It would have the distinct advantage of being able to spin up the ship after departure from LEO, and to de-spin the ship when it arrives near Mars.

(th)

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#880 2021-10-13 18:01:29

kbd512
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Registered: 2015-01-02
Posts: 4,895

Re: Large scale colonization ship

tahanson43206,

There won't be any mechanical bearings in a system this large.  Fluid or magnetic bearings are the only practical kind that will work.

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#881 2021-10-13 18:14:06

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

The issue is bearings. Those bearings must be pressure tight, and must sustain the inertia of the Large Ship. And there must be a way for passengers to cross the bearings, to traverse from one part of the ship to the other. Yes, it would make manoeuvres easier, for the reasons you stated.

Remember, the primary reason for keeping the habitation ring to one deck is radiation shielding. With a water wall on the sun-ward side of that deck, floor-to-ceiling, it makes the entire deck a giant radiation shelter. For shadow shielding to work, the two rings would have to be perfectly aligned so one water wall could shield both rings.

::Edit:: Intermediate axis effect should not happen if two axes have exactly the same moment of inertia. With any sort of spinning top, two axes have the same moment of inertia. A smaller ship that isn't a ring, but rather two habitation chambers at opposite ends of a swing arm, the intermediate axis effect becomes an issue.

Last edited by RobertDyck (2021-10-13 18:17:19)

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#882 2021-10-13 18:23:22

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

Latest image. Not a new render with Blender, just edited. This shows SpaceX Starship with same diameter as the Large Ship hub. So these are to scale. Starship will be used to deliver passengers.
pdgxUPa.png

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#883 2021-10-14 18:19:42

kbd512
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Registered: 2015-01-02
Posts: 4,895

Re: Large scale colonization ship

RobertDyck,

RobertDyck wrote:

The issue is bearings. Those bearings must be pressure tight, and must sustain the inertia of the Large Ship. And there must be a way for passengers to cross the bearings, to traverse from one part of the ship to the other. Yes, it would make manoeuvres easier, for the reasons you stated.

If the motor is external to the pressure hull and the crew are kept in the two pressurized rotating habitats, then there is no need for an airtight seal.

RobertDyck wrote:

Remember, the primary reason for keeping the habitation ring to one deck is radiation shielding. With a water wall on the sun-ward side of that deck, floor-to-ceiling, it makes the entire deck a giant radiation shelter. For shadow shielding to work, the two rings would have to be perfectly aligned so one water wall could shield both rings.

I think the radiation shielding needs to be affixed to the hull, meaning multi-functional radiation / debris / thermal protection tiles that passively shield the ship from CME / SPE, along with active radiation shielding from GCR, most of which is relativistic Hydrogen ions.  I don't think there's much you can do about the heavier nuclei.

I was thinking BNNT fiber reinforced composite, or maybe something like this:

Hybrid Self-Reinforced Composite Materials Based on Ultra-High Molecular Weight Polyethylene

Edit:

I thought this publication provided by OSTI was an interesting read:

Polyethylene as a Radiation Shielding Standard in Simulated Cosmic-Ray Environments

Edit #2:

As always, actual experimentation in space is best:

Performances of Kevlar and Polyethylene as radiation shielding on-board the International Space Station in high latitude radiation environment

Having enough water in the rotating habitat to make a difference as it pertains to CME / SPE would be incredibly heavy, and unlikely to remain balanced to the degree required for adequate vehicle stabilization, assuming the water was part of the potable water supply.  On naval ships here on Earth, we frequently (continuously, in actuality) have to pump both fresh water and fuel between different tanks to assure adequate trim stabilization of the ship, as the supply of the consumables is continuously replenished / depleted / circulated around the ship.  Basically, there would have to be serious slosh baffling and pumping equipment installed to prevent, for example, when the cooks start using 2,500 gallons of water for a meal from seriously destabilizing the vessel.  Add all the circulation for toilets / showers / faucets, and you're talking about a complex mass redistribution task.  When feeding a couple thousand sailors, it was common to use far more water than that.  For feeding 2,500 people 3 squares a day, I would expect a mass of 9 to 10 tons of water to be drawn from the potable water tanks and consumed, prior to becoming grey water and subsequent recycling back to potable water.  Possible to do and still adjust to stabilize the ship?  Sure, it's possible.  Practical?  Maybe, maybe not.  It won't be simple or easy to do, that's for sure.

RobertDyck wrote:

::Edit:: Intermediate axis effect should not happen if two axes have exactly the same moment of inertia. With any sort of spinning top, two axes have the same moment of inertia. A smaller ship that isn't a ring, but rather two habitation chambers at opposite ends of a swing arm, the intermediate axis effect becomes an issue.

This ship is not the same as a spinning top, though, is it?

That's over-simplifying how mass is distributed aboard an actual ship, is it not?

If you have to move tons of water around the ship to balance it perfectly, then it's going to exhibit this effect to some degree.  The severity of the effect is a question of mass imbalance as water is consumed and pumped around the rotating section of the ship.

Last edited by kbd512 (2021-10-14 18:57:02)

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#884 2021-10-16 06:53:03

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 8,012

Re: Large scale colonization ship

RobertDyck is speaking today at the Mars Society 2021 Conference.

He'll be speaking about Newfoundland at 4 PM California time: 6 PM Texas, 7 PM New Hampshire, and 11 PM Universal Coordinated Time.

He'll be speaking about the Large Ship at 5 PM California, 7 PM Texas, 8 PM New Hampshire, and midnight in Greenwich.

It is important to work out any bugs in the registration process well ahead of the events to be attended.

Registration is free, but it is a good idea to expect to have to go through at least one round of password reset before things settle down.

There should be a few members of NewMars forum in the live audience.

A video recording of each presentation will be available for viewing some time after the conference, but a delay of many days should be expected.

(th)

::EDIT:: Corrected times for Texas. Texas is in the Central time zone, except the western most two counties. McGregor is near Waco, south of Dallas, so definitely Central time zone. - RobertDyck

Thanks for the correction!  I was going by Houston time, which is an hour greater than my local time.

This comes up when I'm trying to attend meetings of the North Houston chapter of National Space Society.

Glad to have the distinction pointed out, so I can avoid thinking Texas has one time zone.

(th)

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#885 2021-10-16 22:44:40

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

Well, only got one question. Rushed through the presentation, skipped some dialog that I wrote, and completely skipped the last slides. But kept it to exactly the time allotted. But only received one question. One friend attended, said he liked it. I don't know, not many comments. Tom, I saw you in the attendee list. What did you think?

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#886 2021-10-17 08:08:55

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 8,012

Re: Large scale colonization ship

For RobertDyck re presentation ...

First, I should mention that I provided blow-by-blow reporting of my experience with the Conference in the Mars Society topic. 

I enjoyed the Newfoundland talk.  It put all the posts you've given us here into a single flow that I thought worked well. The history that followed the disappearance of the British Crown representative is worth study, so a reading list would be worth adding if you give the talk again.  For that matter, a post here would be a good way to make that material easy to find when you need it.

I ** really ** liked the Large Ship talk, as you must surely have expected.  It was good to see a NewMars Moderator in the lineup for the conference.  I thought the talk was well designed for a global audience of wide interests. There were a number of women in the audience, so the details you provided for accommodation and amenities would surely have been of interest.  I don't want to fall into the trap of expectations of what particular groups of people might find interesting, but modest attention to the interests of people in general seems appropriate.

The only suggestion I have for the next time you give this talk is to try to be aware of coughs that might come upon you.  Speaking aloud for an extended period is difficult for anyone, so throat irritation is likely.  It is good to anticipate problems, and to try to mute when they occur.

Now!  To your ** next ** talk....

We have a standing offer to make a presentation to the North Houston Chapter of the National Space Society.

I am willing to ask if they would like to schedule you, if you are willing.  They are booked some time out, so the opportunity will not be immediate, but I'd like for you to have another engagement lined up to help you move the ball. You've made good progress since you started, but other than the new Blender renderings, I didn't see or hear anything newer than a year, and some of it goes back to the beginning.

A message with specification of the key design factors (dimensions, rate of rotation, atmosphere mix) have GOT to become universally adopted SOON if you are going to become the proud witness of the Robert Dyck heading for Mars.

Your interest in getting paid is understandable, but I see it as a roadblock to achievement.  I think you will be handsomely rewarded if you are successful in persuading large numbers of people that you have a good idea and they need to support it financially and politically.

I have a list of attendees that I'll try to post in the Mars Society topic in a day or so.

Congratulations on your representation of NewMars!   Everyone from this group who will be making presentations can use your two talks as a benchmark.

I'd appreciate some coaching for others .... what software did you use? 

Whatever it was, it worked well!

Edit: You made reference to your previous talk about oxygen generation. You've discussed it here as well.

Please consider making available a link to the YouTube video of that talk (if it exists).

(th)

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#887 2021-10-17 11:32:47

kbd512
Administrator
Registered: 2015-01-02
Posts: 4,895

Re: Large scale colonization ship

Robert,

If the presentation was recorded, then I would very much like to see it.

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#888 2021-10-17 11:46:22

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

I presented the chloroplast talk at the 7th Mars Society convention in 2004. That was recorded and sold on DVD. I don't know if it's available on YouTube. I looked but didn't see it. My PowerPoint presentation is available on the Winnipeg chapter website. My presentation notes are in the "notes" section beneath each slide. So don't just look at the slides themselves, also read presenter notes.
Artificial Photosynthesis

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#889 2021-10-17 11:58:55

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

All presentations of this year's convention will be uploaded to YouTube. Plenaries are already uploaded, but very few tracks. My presentations were both Saturday:
PB-5 Dyck: Saint John’s Newfoundland – historical example of settlement
TE-7 Dyck: Large Scale Colonization Ship

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#890 2021-10-17 12:43:14

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

Coughing: when trying to rush, I got emotional and choked up. The cough was to push down the emotion so I could continue to talk. To solve that, I need to slow down. So just more time.

I expected some challenge re advanced life support. The chloroplast oxygen generator is basic to this system. I attended a conference hosted by NASA in Washington DC in 2005. At that time Sean O'Keefe was administrator; he wanted input from non-traditional aerospace, so the purpose was for members of the public to make presentations to NASA. After the conference I spoke to a NASA host. When I raised the chloroplast oxygen generator, she suppressed a chuckle and said it's "too advanced". My system uses life support in each cabin, the rest of the cabin system is based on the system on ISS. Well, add vacuum desiccation toilet taken from the toilet that Russia developed for the Mir2 space station. Grinding dry feces is just a carberator, so not radical. And add the recycling shower developed by a design student in UK. However, post-processing done in "central life support" is far more advanced.

  • electrolysis of concentrated urine into NaOH and KON, producing chlorine and hydrogen gas

  • bubble Cl & H2 gas through NaOH to form salt, food grade

  • bubble CO2 gas through NaOH to form baking soda

  • grow mould on starch to produce amylase

  • react starch with amylase to produce white sugar

  • grow microbe in a vat with water and sugar to produce microbial oil, effectively the same as vegetable oil

  • react KOH with microbial oil to produce liquid soap. Also produce shampoo, laundry soap, dish soap, and dishwasher soap

  • grow a different microbe in a vat to produce replacement for palm oil (heavier vegetable oil)

  • combine regular and heavy microbial oil to make margarine

  • extract urea from urine (after removing salt). Also extract phosphate. Chemically modify urea into ammonia. Dissolve ammonia and phosphate in water, which will produce diammonium phosphate, which is yeast nutrient

Urea is the primary waste product of human metabolism. However the "stinky" part of urine is proteins, pure urea has no smell. Urea is CO(NH2)2
110px-Harnstoff.svg.png
React that so the net reaction adds one molecule of water. One oxygen atom from water combines with carbonyl (CO) to form CO2. One hydrogen to each of the NH2 groups to form ammonia (NH3). Phosphate is PO4. Ammonia dissolved in water with phosphate also dissolved in water form an ion bond, a salt. So they very simply produce yeast nutrient. That is needed for various vats that grow yeast. It provides nitrogen required for protein and DNA, and phosphate is needed for DNA.

Even more advanced: (not included in the convention presentation, no time)

  • genetically engineer a yeast to produce wheat proteins

  • mix pea starch with wheat proteins to make synthetic flour

  • wheat protein can be used without starch to make vegan substitute for chicken nuggets & patties

Note: flour is 70-75% starch, depending on grade of flour. The vast majority of the rest is protein. 80% of wheat protein is gluten.

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#891 2021-10-17 13:14:04

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 8,012

Re: Large scale colonization ship

For RobertDyck re presentation:

Please see update at: http://newmars.com/forums/viewtopic.php … 92#p186192

The folks in the Large Ship list might be worth a follow up inquiry, to see if their interest was more than just transitory.

In particular, I'd be interested in Dr. Nilsson, who seemed to like your talk.  He is .... actually... I don't ** know ** he is in the medical field.

He showed interest in medicine, so he ** might ** be a doctor of Medicine.

Our new candidate for membership in the forum is actively seeking a position for Medical doctor training.

It might be fruitful to bring those two together.

The doctor(s)(?) might be able to help you plan the diet for the passengers and crew.

You're off to a terrific start, but at some point, if you're going to (literally) get this concept off the ground, you are going to need help, and lots of it.

You've already asked for help at least once, so you've broken the ice.

i'd like to see a scale working model flying soon, and the sooner the better.

The model needs to test the issues raised by kbd512 re stability in orbit as masses shift inside the moving/rotating vessel.

In my opinion, you need to be ready in case some person or organization with deep pockets decides to hire you to build this thing.

Admittedly I don't know more than a tiny fraction of what's going on on Earth these days, but I've certainly NOT heard of anyone else on the track you are on, so I'd like to see you achieve visibility and (hopefully) support before someone else catches the winds of change.

(th)

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#892 2021-10-17 13:18:05

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 8,012

Re: Large scale colonization ship

Special for RobertDyck ....

Please consider making an offer to the Government of Canada (I know, I know) ...

The bid would be to travel throughout the entire country at their expense, to sell the population on the proposition of building Canada Spaceways (or something similar) using your vision as the prototype.

The people you've met while on your work related travels are showing signs of lack of life purpose.  A strong vision of the entire Nation deciding to become the premier provider of travel services to Mars is completely achievable.  It is a SOCIAL problem!  It needs a capable sales person to achieve the collective enthusiasm and sustained support to make it happen.

How you feel about this government, or ** any ** government is irrelevant!

(th)

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#893 2021-10-17 13:34:06

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

Dr. Nilsson is a friend. He lives in my city. He has education, but his day job is a specialty retail store that he runs with his significant other. I would like to say common law wife, but Tanya got upset once when I used that term. Ok, she doesn't want their relationship characterized. They were involved in politics; she ran as a candidate for the provincial election a few times, and federal election twice. She never got elected. Our party is the current federal government of Canada, it's one of the two big parties, but hasn't won provincially since the mid-1950s. She did reasonably well considering, but still came 3rd. She decided after the 2006 federal election that she wouldn't run again, she's focusing on her business. I got Walt involved, which wasn't hard. He enjoys academia, it's a lot more stimulating than running a small retail store. He let me give my Newfoundland presentation one-on-one to time it, he said it was good. We didn't have time to practice the Large Ship presentation, so I had to do that on my own. I'll ask if he wants to get more deeply involved.

Oh! You captured the list of attendees for my talks. Frank Crossman attended my Newfoundland talk. He runs Mars Papers. All presenters were sent an email to format the presentation as a PDF so Frank can publish them. And Bruce MacKenzie attended my Large Ship presentation. He founded/runs the Mars Foundation. He invited me to participate in his Mars Homestead Project in 2005. I was honoured. He's a friend who I met a Mars Society conventions, basically only see at convention. Was nice to meet with him via Zoom for a presentation he hosted.

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#894 2021-10-17 13:58:03

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

Well, I met Marc Garneau when he was president of the Canadian Space Agency. Met him again after he became a federal Member of Parliament. When he was president, it was his idea to send a Canadian rover to Mars. I tried to lobby for funding to realize his vision. He appreciated that, but unfortunately it didn't happen. I spoke to Marc and another astronaut about a Canadian led international mission to send humans to Mars using Russia's big rocket. In 2006 I was getting impatient, the US government didn't seem interested. Using the Russian Energia rocket is an idea I got from Robert Zubrin's book, it was very popular in the first years of the Mars Society. SLS wasn't even an idea yet, and Boris Yeltsin was very friendly to the West. That was before Putin. But nothing happened with that either.

The issue with indigenous people in Canada is complex. I could give a long-winded explanation, but short version is using space isn't going to resolve their problems. One problem is some leaders in the indigenous community are pulling in the wrong direction. I'm sorry but giving all land for all of Canada back to indigenous people and kicking out anyone who isn't indigenous just isn't going to happen. I'll see what government support exists for a space start-up. Government has a lot of programs.

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#895 2021-10-29 21:46:46

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

My talk is now available on YouTube: Large Scale Colonization Ship (click image for YouTube video) 25 minutes, 5 seconds
For some reason the volunteer who edited this chose the second slide for the title image of the YouTube video.
maxresdefault.jpg

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#896 2021-10-29 22:52:54

kbd512
Administrator
Registered: 2015-01-02
Posts: 4,895

Re: Large scale colonization ship

Robert,

Two thumbs up.  Looks great.

There were some comments on YouTube regarding no mention of propulsion or thrust loads or what happens if you're unfortunate enough to encounter a SPE / CME during thrusting periods.

The comment about nobody welding in space was pretty funny, so the same commenter must be completely unaware of all the work that NASA and ROSCOSMOS have already done, or the fact that we could potentially cold weld in space.

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#897 2021-10-29 23:19:53

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

Thank you. I should mention there was one question. The video is 25 minutes, we had 30 minutes total. It was supposed to be 25 minute presentation plus 5 minutes of questions. I ended just as the moderator gave me the 5 minute warning. The one question asked if this is a cycler. I said no. This ship would travel from Earth orbit to Mars orbit and back. It would park in planetary orbits between trips. Starship is designed to carry 100 passengers to Mars. That's with recycling life support and plenty of water and an open space. If configured with airline seating, it can carry 200 passengers. So a Starship designed to carry passengers to the Large Ship could carry 200 passengers at a time. Since the Large Ship carries 1,000 passengers, that means 5 trips. Furthermore, there will be cargo. Parked in Mars orbit you can make multiple trips between the Large Ship and surface, but a cycler passes the planet at high speed, only one rendezvous attempt possible. Furthermore, return to Earth will require resupply with propellant and food. As well as any passengers who want to return to Earth. If the ship requires repair or maintenance, that can also be done while parked in planetary orbit. Again, that can't be done with a cycler that passes the planet at high speed. When parked in Earth orbit, the Large Ship can be used as a space hotel to generate some additional revenue between voyages.

The person who asked the question didn't like my answer. He claimed not making it a cycler defeats the point.

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#898 2021-11-07 07:52:44

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
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Re: Large scale colonization ship

I did some calculations for the chloroplast oxygen generator.
According to NASA, each adult required 0.84 kg of oxygen per day.
Maximum capacity is 6 passengers per cabin.
Energy required for photosynthesis is 450 kcal/mol of oxygen. Reference
Atomic weight of oxygen is 15.999 so molecular weight of O2 is 15.999*2 = 31.998 g/mol
Therefor total energy required is 70,879.43 kcal per day.
Conversion to metric: 1 kcal = 1.16222 Wh. kcal is kilocalories, Wh is watt-hours
Total energy required is 82,377.49109 Wh
efficiency of photosyntehsis is 28.2%. Reference
obviously there are 24 hours per day.
Power required is 12,171.61511 Watts of sunlight.
At Earth's average distance from the Sun, sunlight reaching top of atmosphere is 1,360 W/m². Reference
Therefor collection area per cabin must be 8.949716996 m²
If collector is a parabolic mirror reflecting into a secondary mirror which reflects into a light pipe, then radius of that mirror must be 1.687833937 m, diameter 3.375667874 m.
That's large. If the parabolic mirror is cut into a square, so the squares can be stacked, then each side of the square must be 2.991607761 m.

This is a problem because each cabin is 2.4 metres wide by 2.43 metres high. With 4 cabins across the width of the habitation ring, 4 mirrors are required.

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#899 2021-11-07 08:31:37

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 8,012

Re: Large scale colonization ship

For RobertDyck re #898

It is ** good ** to see Large Ship back in view...

My only offer of a suggestion is to take into account that the sunlight available at Mars is much less than your initial draft shows.

The mirror/collector would need to be larger, if you are thinking of using solar power.

On the other hand, is it possible to simply design a large solar power collection system for the ship, and distribute power to the cabins as needed?

I note that a modern passenger liner in ocean service on Earth provides power to all cabins from a central supply.

(th)

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#900 2021-11-07 11:51:35

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,898
Website

Re: Large scale colonization ship

Well, we could raise the height of the mirror to waist level of the upper deck. I don't want to completely cover the sun-facing windows of the upper deck. The upper deck will be observation and greenhouses. We want good views in all directions from the observation deck, not just deep-space facing. And the greenhouse will need illumination. I had said photovoltaic arrays dangling from the habitation ring on the sun-facing side; both for power and to shade the radiators. We could put reflectors/collectors there. Photovoltaic arrays could be moved to the open space between hub and ring. That makes solar power collection centralized. cabin windows would have a hole cut in the collector mirror. After all, this isn't a telescope, so doesn't have to be optically symmetrical. It's just about collection area.

I don't want to use photovoltaic panels to convert sunlight to electricity, just to use LED lights to convert electricity back to light. That's inefficient. Unless... we could use gallium-indium-nitride photovoltaic panels with 70% efficiency. LED lights have 85% efficiency. 70% * 85% = 59.5% efficiency. Ensuring LED lights produce specifically the colours that plants use. Plants use 53% of sunlight available. No, that's still not good enough. We would be better off with reflectors, light pipes, and window to let light in. And that's dependent on manufacturing gallium-indium-nitride photovoltaic cells with 8 junctions. In year 2000, Los Alamos National Laboratory did a study and noticed this particular photovoltaic cell has a light absorption spectrum that almost perfectly matches our Sun, so should be very efficient. They hired the materials lab at University of California in Berkeley to fabricate one so they could test if reality matched their theory. They found it works. It's transparent to light it doesn't convert to electricity, so they can stack them. Adjusting the concentration of nitride alters the light absorption spectrum. Current photovoltaics for space use different chemistries for each junction, the one that's opaque goes on the bottom. Using the same chemistry but different concentration makes manufacturing simpler. With 2 junctions it was 56% efficient, with 3 junctions 64% efficient, and 36 junctions 72% efficient. A researcher later calculated 8 junctions to be 70.2% efficient. Remarkable, but for some reason no one is manufacturing them. Terrestrial solar cell manufacturers want manufacturers for space to pay for technology development, then they want to steal it. Manufacturers for space don't want to spend millions just to have someone else take their work without compensation. And manufacturers for space have a long-term business plan to gradually increase efficiency from 24% to 45% over decades, gouging their customers for each fraction of a percent increase. They're currently at 32%. Yes, they know how to make 45% efficient; they just don't want to. Current space photovoltaic panels with LED efficiency would give 27.2%, which is far too poor.

According to the Wikipedia article linked above as reference for photosynthesis efficiency, 53% of sunlight is the right frequency (colour) for photosynthesis. 30% of photons are lost due to incomplete absorption. Could we improve that by surrounding chloroplast bags with mirrors? Light not absorbed would reflected back through? 24% is lost due to wavelength mismatch with 700nm energy level. I assume that means a single photon causes one pair of water molecules to cleave into O2, 4 hydrogen ions, and 4 electrons. The electrons travel down the electron transport chain to power further steps of the light reaction, and hydrogen ions power ATP synthase. A photon of higher energy just powers the same chemical reaction, so the additional energy of blue photons are wasted. Nothing we can do about that. The article talks about conversion to d-glucose and sugar consumed by the leaf during night/dark. Invitro chloroplasts won't have to power the rest of the plant, the chloroplasts will be separate. And they won't have mitochondria to break down sugar as an energy source, so no photorespiration at all.

Most of the habitation ring is cabins. So no need for light collectors over common areas: laundry, kitchens, dining rooms, bar, bridge, sickbay, gym, spoke elevators. But that's not a large portion of the habitation ring. Covering those areas with light collectors wouldn't provide enough light to be worth it. May as well cover the sun-facing exterior hull of those areas with photovoltaic panels.

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