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Mars_B4_Moon

Member

Registered: 2006-03-23

Posts: 9,267

Re: Large scale colonization ship

recent news articles these past months seem to admit humanity should have already should have tested an artificial gravity station

We Don't Know Enough About the Biomedical Challenges of Deep Space Exploration
https://www.universetoday.com/163469/we … ploration/

“First, we are expecting that lunar gravity could impair a number of functions in a way that looks quite differently from that investigated on board of the ISS, where the body is fluctuating [being in] free fall,” Bizzarri said. “How different g values can impair biological functions still awaits a proper model of investigation.”

'most significant challenge is dealing with the effects of weightlessness or reduced gravity.'

Perhaps the best or easiest method would be having devices to allow exercises in an artificial gravity condition.

Simplified equations for object trajectories in rotating space habitats and space juggling
https://www.nature.com/articles/s41526-023-00328-6

tahanson43206

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Registered: 2018-04-27

Posts: 17,181

Re: Large scale colonization ship

For RobertDyck ....

You attended the Mars Society convention, and appear to have become distracted by War, to the extent you created a topic on the subject.

War is something you cannot do anything about, so (from my perspective) it is a waste of your time, and a waste of everyone's time.

Please put the entire issue in a safe, secure location, and return to developing Large Ship.

(th)

RobertDyck

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From: Winnipeg, Canada

Registered: 2002-08-20

Posts: 7,811

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Re: Large scale colonization ship

Mars_B4_Moon,
You're right. It's incredibly frustrating that it was a principal purpose of ISS. The Centrifuge Accommodation Module was designed for that, built, and ready to launch. It was never launched, only one more Shuttle launch would have been required. There was an external tank and pair of solid rocket boosters, but President Obama didn't want to risk it. He wanted at least one Shuttle on standby as a rescue vehicle, and there wouldn't be for the last one. If something did go wrong, they could shelter in ISS and Russia could send a Soyuz. But he didn't want to rely on the Russians.

I have posted before that new technology could launch it. Falcon Heavy could launch it into orbit, and a service module from a Cygnus cargo ship could rendezvous with ISS. Then just as a normal Cygnus mission, the station's arm could grab it and berth to ISS.

The Centrifuge Module is currently on display outdoors in the parking lot of the Japanese space agency in Tokyo. It may need some cleaning before launch, but it's still there.

RobertDyck

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From: Winnipeg, Canada

Registered: 2002-08-20

Posts: 7,811

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Re: Large scale colonization ship

With all the StarLink satellites, I keep thinking about aerocapture. That's a special form of aerobraking. With aerocapture, the ship approaches the planet at full interplanetary speed. The ship skims the upper atmosphere to slow down. The ship must slow down enough to enter orbit. All those satellites in Low Earth Orbit will be a problem because the Large Ship could plow through them like a snow plow. The following link is a YouTube video clip just 5 minutes long. Actually 4 minutes and 57 seconds. From the movie "2010: The Year We Made Contact". The movie was produced in 1984, events were supposed to be in 2010. They seriously expected we would have a large ship with a rotating section for artificial gravity and hibernation, able to travel all the way to Jupiter. What we actually have is sad. The movie was a sequel to "2001: A Space Odyssey". In this movie the Russians build a ship to travel to Jupiter, an American scientist is brought along to revive the American ship left orbiting Jupiter in the first movie. In the movie Russia and America work cooperatively, but something happened causing geopoliticial tension. Astronauts/cosmonauts try to work together even though their politicians are acting like asses. At least they got that part right. Click image for video.

tahanson43206

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Registered: 2018-04-27

Posts: 17,181

Re: Large scale colonization ship

Here's a report that might fit into the Large Ship scenario ...

http://newmars.com/forums/viewtopic.php … 50#p217150

(th)

RobertDyck

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From: Winnipeg, Canada

Registered: 2002-08-20

Posts: 7,811

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Re: Large scale colonization ship

I found this floor plan for berthing compartments onboard a Ford class carrier. So what do you guys think of packing passengers as tightly as sailors on a US navy ship?

I said standard cabins would be per pressure subcompartment: 4 on the left of the corridor, 4 on the right. Outboard cabins have a window, inboard cabins do not but do have a 4k TV with high-def camera outside. Passengers could select which camera they want to view. Standard price per cabin, regardless how many passengers. Most dense is based on 3rd class of the Titanic, but with an ensuite bathroom the size of an airline bathroom.

Navy version: no ensuite bathroom. No drawers under lower bunk, but under mattress storage is retained. Loser bunk is right on the floor. That is storage is on the floor, mattress pad is on that. 3 bunks high. Nimitz class bunks have 17 inches (17") from top of mattress to bottom of bunk above, with 3" thick mattress. Our ship could have 18.75". Not much difference, you still couldn't sit up in bed. Ford carrier berth is 77.5" x 27.5". Nimitz berths are 72" x 30". I said our ship will have berths based on civilian "single" beds: 75" x 30". With 2 beds along the left wall, 2 on the right, and 3 bunks/berths/racks high, that's 12 racks per cabin. Nimitz carriers had a lounge for each berthing compartment but Ford carriers don't. In navy configuration 2 of the 8 cabins in a pressure subcompartment would be bathroom, total 6 toilets, 6 sinks, 4 showers.

Civilian 3rd class has 6 passengers x 8 cabins = 48 passengers. Navy version has 12 crew x 6 cabins = 72. Civilian version has 1 toilet for every 6 passengers. Navy version has 1 toilet for every 12 crew, and 1 shower for every 18.

Tom expressed concern over how crowded 3rd class cabins are. I said cabins would be configured to passenger requirements. Navy configuration would have to be an entire subcompartment. Would anyone want this?

::Edit:: I said civilian 3rd class has 2 rows of drawers under the lower bunk; one row for passenger in the upper bunk, one for lower. Navy version has no drawers. Instead navy version has lockers. Instead of night stands at the end of the aisle, navy version has lockers. 3 lockers wide x 4 high, so every crew member gets one. Each locker 10" wide x 23.5" high, assuming sheet metal with negligible thickness walls. If you want to be picky, wall thickness takes away from those dimensions. Locker depth? Locker is beside bunks farthest from the door; individuals have to be able to get in and out of their bunk.

These lockers would cover the window. Civilian 3rd class inboard cabins have no window, but have a wall mounted 4k TV instead. But navy version covers all wall surfaces, no room for a TV. However, Wifi enables tablets, laptop computers, and smartphones.

Last edited by RobertDyck (2024-01-05 12:30:43)

GW Johnson

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From: McGregor, Texas USA

Registered: 2011-12-04

Posts: 5,459

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Re: Large scale colonization ship

You can have tight sleeping quarters if you have lots of room to live somewhere else.  Might not be popular,  but it is doable.

GW

---

GW Johnson
McGregor,  Texas

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

tahanson43206

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Registered: 2018-04-27

Posts: 17,181

Re: Large scale colonization ship

For GW Johnson re #1457

Thanks for the reminder that human beings need some room to enjoy or at least endure away from the bunk space. 

It is good to see Large Ship back in the active list!

I'd very much like to see this topic back in growth mode. We don''t need rapid growth followed by a pause ... steady slow growth is what this topic needs.

(th)

RobertDyck

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From: Winnipeg, Canada

Registered: 2002-08-20

Posts: 7,811

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Re: Large scale colonization ship

A friend is trying to start a business. He wants me on his board of directors. He's counting on me for technology projects. He gave me a salary offer, and it's good. However, that depends on his financing coming through. A guy in California has been promising financing "any day now". Yesterday my friend called me, said his contact has money. He will fly to California to file documents to open a mining corporation. He's a retired miner. The project is to re-open a gold mine. It was closed when drop in gold price made the mine no longer profitable. Now that gold prices have increased, they want to purchase the mine and restart mining. Due to the time involved, I'm skeptical of the guy promising money. If it does come through, great! But I'm not counting on it.

The guy I spoke with at Red River College about students doing 3D graphics has not called me back. He said I would have to talk to him in the spring for students to work on this starting in the fall.

Robert Zubrin is skeptical of a chloroplast oxygen generator. His new Mars Institute will develop technologies for Mars, with a focus on biotech and applications on Earth. He thinks chemical synthesis of food will be more efficient than nature. I'm skeptical of that. Chemical synthesis would produce something I wouldn't want to eat. And photosynthesis of isolated chloroplasts in an environment with elevated CO2 is more efficient than he thinks. I should send a formal proposal but already have a negative bias from Dr Zubrin.

My girlfriend insists I spend every day at her apartment and refuses to move into my house. So I'm away from my computer most days. It has resulted in many arguments. I don't know how to deal with that. I can't do serious work on a smartphone.

Work has been sparse. 5 days work in November, plus one assignment that took me 10 minutes but billed at 3 hours. No work at all in December, and the next scheduled assignment is March, over Easter weekend.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 28,884

Re: Large scale colonization ship

There are two minds of thought in this, and crew should have a smaller cabin as they are actively no in them as much as those going for other activity where normal operations would be interfered with by having so many in the way other than times that allow them to go to meals and other such smaller activities as deemed needed.

tahanson43206

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Registered: 2018-04-27

Posts: 17,181

Re: Large scale colonization ship

For RobertDyck re #1459

It is time for Large Ship to resume development, even if the schedule is restrained.

In light of the special circumstances in play (per your description) I am wondering if you could persuade your friend to give you a place in the basement or other out-of-the-way location where you could build a small computer alcove, and build a special purpose system just for this project.  If you friendship is stable otherwise, this might be a solution that would allow you to return to work on Large Ship.

It is clear (to me at least) that this project needs a dedicated human being to give it the strength it needs to build a strong root system.  The NewMars forum is a good place for that root system to build up, but it needs the attention of a person with leadership skills and the persistence you have demonstrated over a number of years, in bringing the concept as far as you have.

Speaking of work.... I assume (but don't actually know) that you must have an account in LinkedIn, but if you don't I'm hoping you will consider creating one.

A while back you mentioned the possibility of helping a gent who wants to restart a mine.  There are a ** lot ** of minerals beside gold that are valuable, and a mining enterprise might do well by pursuing other substances besides gold.  Perhaps the substance of interest was uranium? I'm having difficulty remembering the specific substance of interest.

(th)

RobertDyck

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From: Winnipeg, Canada

Registered: 2002-08-20

Posts: 7,811

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Re: Large scale colonization ship

I have to do some plumbing repairs and clean the house, then convince her to move into my house. There's a facility with self-storage rooms 3 blocks from my house, her stuff can go there. Her father moved to a nursing home, then died. His house has been sold. For the last year she has lived in a bachelor apartment (aka studio apartment) in an old building downtown run by a company notorious for not doing maintenance. Slum landlord. Her tiny place doesn't have a basement or even a bedroom.

The gent who wants to restart a mine has gotten connected to someone in California who promised investment money. That guy claimed the money will arrive within 48 hours, but has said that for.over a year. It's obviously a scam. I don't  know what happened to the previous group he was associated with, individuals in semi-retirement who all have skills and experience. My friend is getting old, the last few months is showing signs of the early stages of dimentia. His latest story is a car trip with a friend, which sounds more plausible.

Another couple are friends involved in politics. In 2004 and 2006 she was the federal candidate for our electoral district. Her significant other (I would say common-law husband but she got upset when I tried to clarify), was president of the electoral district association before I was. I won the nomination after she said she wouldn't run again. However, someone buried me, I had to be replaced, my name wasn't on the ballot. Now for the first time all of us don't want to even vote for our party. It's that bad. A local politician (perennial also-ran) asked me to speak to city council on a pro-business issue. The issue is consistent with what the federal government is trying to do so does have a chance.

tahanson43206

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Registered: 2018-04-27

Posts: 17,181

Re: Large scale colonization ship

For RobertDyck re #1462

Thanks for this update on the situation(s) around Large Ship!  Best wishes for all possible success in resolving all those uncertainties!

I'd like to see Large Ship resume progress, and it sure looks and sounds as though you are taking steps to make that happen. 

FYI ... your interest in politics is a distraction.  It may be important in some context, but is like the drag of the atmosphere at 1000 meters.  Please try to move to a higher elevation where you have less drag.

I have created a new Category for Projects in the phpBB3 test forum on Azure.

Please register and either SpaceNut or I will make you a moderator.  We need someone to learn about Moderator functions, and SpaceNut and I are both busy trying to understand the role of Admin.

When you register, it is important to create a post, or we'll never know you've applied.  Please put a post in the new forum for Large Ship. Please take an optimistic position in your first post.  You have my support to resume forward momentum, and potentially other forum members will provide at least moral support.

We can (and hopefully will) be able to recruit (volunteer/pro-bono) talent to help you with Large Ship.

We have allowed a lot of time to go by without much progress.  Before the Zoom meetings went away (due to Mars Society needs) you and kbd512 were looking intently at the problem of construction of the Large Ship in orbit. That is a difficult problem, and no one in this forum has the background necessary to make meaningful progress.  The solution is to recruit the talent we need to provide the leadership to help that talent stay focused on the problem to be solved.

We do not need the distraction of politics to bog down the folks working on Large Ship.

Politics probably has a place in the Universe, but I have difficulty seeing how it has anything to do with Large Ship.

(th)

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,181

Re: Large scale colonization ship

For RobertDyck...

I have created a new topic for Large Ship inside Projects at:
http://40.75.112.55/phpBB3/index.php

The new topic is dedicated to the Test Kitchen on Earth to emulate the actual kitchen(s) in Large Ship, as well as in the habitats on Mars that adhere to the RobertDyck atmosphere specification for Large Ship ca 2020.

You are welcome to register in the phpBB3 test site and begin to fill out the new category for Project >> Large Ship.

As soon as you register and provide a test post, either SpaceNut or I will admit you to Regular Members and to Moderators.

SpaceNut and I have learned (through trial and error) not to remove you from Regular Members when we promote you to Moderator.

(th)

RobertDyck

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From: Winnipeg, Canada

Registered: 2002-08-20

Posts: 7,811

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Re: Large scale colonization ship

The cooking experiment will require a real facility. Reducing pressure to 1/2 atmosphere means peak of Mount Saint Elias, or Denali (Mount McKinley). Doing it in a city requires a vacuum chamber pumped down to 1/2 atmosphere. Going from sea level to that requires hours of oxygen prebreathe. The goal is to eliminate oxygen prebreathe on the Large Ship or Mars, but ironically you would need it on Earth.

tahanson43206

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Registered: 2018-04-27

Posts: 17,181

Re: Large scale colonization ship

For RobertDyck re #1465

Why would you need any such thing as pre-breathing?

The amount of oxygen in the air in the test kitchen would be exactly the same as on Earth, at sea level.

The only difference would be the amount of inert gas.

If your theory is correct (and I have to assume it is) then a person could travel from Earth conditions to 3 PSI oxygen "space suit" and then to the test kitchen without having to pause at all.

OK ... I ** think ** I may be getting a glimmer of understanding of your concern ... pre-breathing would be needed for a student or worker entering the test kitchen. Once the person is ** in ** the test kitchen, then transition to the space suit would NOT requre pre-breathing.

OK ... the solution is to perform all cooking experiments using waldos ...

Once the test kitchen is evacuated to your Large Ship atmosphere prescription, then it can be held there, and materials to be tested can be moved in and out thorugh sealed portals.

It would be a lot of work to set this up, but I think NASA would (or should) be interested.

Your atmosphere prescription would work on the Moon, and NASA is ** definitely ** going to the Moon.

(th)

RobertDyck

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From: Winnipeg, Canada

Registered: 2002-08-20

Posts: 7,811

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Re: Large scale colonization ship

Passengers travelling to the Large Ship could prebreathe oxygen on the ground before Starship launches. That's assuming a rapid rendezvous, about an hour after launch. But if rendezvous takes a day, passengers and crew can go through slow decompression on Starship. SpaceX Dragon mission 6 took 24 hours and 43 minutes from liftoff to ISS contact.

The issue is nitrogen dissolved in your blood. If you go through decompression too quickly, that will come out of solution, forming bubbles like a bottle of soda pop. In pop the bubbles are CO2, but in your blood it's N2. 78.084% of Earth's atmosphere is N2. As you breathe, gasses pass through thin membranes in the tiny air sacks of your lungs. Oxygen binds to hemoglobin molecules in red blood cells. But CO2 is carried by your blood as well, and nitrogen dissolved. If bubbles form, they block tiny blood vessels, preventing blood flow to that part of your body. Lack of blood flow means lack of oxygen, causing tissues to die. This is called "The Bends".

SCUBA divers who breathe whole air suffer this. High pressure at depth in the ocean causes more nitrogen to dissolve. If the diver returns to the surface too quickly, that causes the bends. Ascending slowly allows nitrogen to be expelled through your lungs as breath.

Decompressing from normal Earth surface pressure to the lower pressures we're talking about for Mars would do the same. One reason for lower habitat pressure on Mars is so habitat and spacesuit have pressures sufficiently close to each other that extended decompression time or oxygen prebreathe time is not necessary.

Oxygen prebreathe means you don't decompress, but this allows your lungs to exhale nitrogen from your blood. Oxygen prebreathe at reduced pressure would expell nitrogen faster, but again the pressure difference must be slight to prevent bubbles from forming in your blood.

Difference between 1 atmosphere and 1/2 atmosphere is enough that you must either decompress slowly, or go through oxygen prebreathe to expell nitrogen. Again, to prevent bubbles.

RobertDyck

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From: Winnipeg, Canada

Registered: 2002-08-20

Posts: 7,811

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Re: Large scale colonization ship

Apollo used 3.7 psi pure oxygen in their spacesuits. Apollo Command Module launched with 1 atmosphere pressure, but would slowly blead air and dilute with pure oxygen until the final operating pressure of 5.0 psi pure oxygen. Skylab used 5.0 psi with 60% O2 / 40% N2. So this meant Apollo and Skylab astronauts could go out in a spacesuit and back in without having to worry about decompression or the bends.

GW Johnson

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From: McGregor, Texas USA

Registered: 2011-12-04

Posts: 5,459

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Re: Large scale colonization ship

Variants of the same A-7 suit were used on the X-15,  Mercury,  Apollo,  Gemini,  and Skylab.  Baseline pressure was 3.7 psia,  but it could have been less.  Not a lot less,  but 3.0 psia works.

There is a rule-of-thumb for determining whether you have to do pre-breathing to blow off nitrogen before being suited up at lower pressure in a pure-O2 suit.  The partial pressure of nitrogen in the two-gas atmosphere you are breathing,  divided by 1.2,  is the min pure-O2 suit pressure you can use without doing pre-breathing.  You can use higher without pre-breathe,  but not lower.  For synthetic air at 14.7 psia,  20.94% oxygen,  the nitrogen partial pressure is 11.62 psia (O2 is 3.08 psia).  11.62/1.2 = 9.68 psia,  which would be the min piure-O2 suit pressure for no pre-breathe.  See the problem? 

There's both short-term and long-term health issues for low O2 partial pressures,  or low atmosphere pressures at Earthly air composition.  Short term,  the oxygen mask limit is the pure O2 pressure at about 45,000 feet,  or maybe only 40,000 feet.  Above that for more than several seconds,  fighter pilots have to wear some sort of pressure suit so they can do pressure breathing,  and still have the cognition to function as pilots.  40 kft is 2.73 psia atm pressure,  which within a vented O2 mask is the O2 pressure corresponding to a suit.  At 45 kft this is 2.15 psia.  Which is exactly why a pure O2 pressure suit can be lot lot lower than 3.7 psia.

There is another limit on that short-term scenario:  loss of moisture from the lungs,  causing excessive drying of tissues,  risking cracking and bleeding.  That happens after some hours of exposure,  and is not much of a problem if the pure O2 pressure is 3.0 psia.  Which is where my min acceptable suit value comes from for an all-day EVA-type activity.

Long-term,  the experiences with long-term hypoxia and long-term childbirth difficulties show up at about 9000 feet elevation.  No higher than that,  routine health is all the same,  more or less independent of elevation.  Above that (and people do live above that),  chronic hypoxia indications increase sharply with elevation,  particularly above 13,000 feet.  And complications of childbirth increase in frequency rather noticeably with altitude.  At 9000 feet,  pressure is 10.51 psia,  and the partial pressure of O2 is 2.20 psia (that of N2 is 8.31 psia).  You pretty much must have a partial pressure of O2 at or larger than 2.20 psia in any two-gas habitat atmosphere,  for long-term health. 

There is another danger,  when one uses lower-pressure habitat atmospheres enriched in O2:  enhanced fire danger.  In sea level Earthly air at 14.70 psia and 70 F,  the mass concentration of oxygen measures 0.275 kg/cu.m.  For an Arrhenius reaction rate model as an indication of fire spread rapidity,  rate ~ [Cf^n + Co2^(1-n)]exponential T-factor.  n is usually in the vicinity of 1,  so n-1 is also in the vicinity of 1.  You basically have the same threat or less from fire spread rates as we experience here on Earth,  if your oxygen concentration is at or below that 0.275 kg/cu.m figure.

You also have to worry about leak-down effects.  10% pressure drop is the usual rule-of-thumb for suits.  And presumably habitats.

Here is what I get for 0.45 atm 32-gas in the habitat at 45% O2 and 55% N2:  Pp O2 = 2.976 psia + Pp N2 = 3.637 psia = Ptot = 6.613 psia.  Leaked down 10% but maintaining the 45-55% composition,  that is 2.645 psia O2 + 3.233 psia N2 = 5.878 psia total.  The design hab corresponds to a min 3.0321 psia pure O2 suit for no pre-breathe,  and a 0.257 kg/cu.m O2 concentration. 

Even leaked down,  the 2.645 psia O2 meets the 2.200 psia O2 long-term exposure criterion,  the 3.03 psia suit allows far easier MCP designs,  and the 0.257 kg/cu.m means the fire risks are a tad less severe than a sea level 70 F day on Earth.  The 3.03 psia suit is way better than vented O2 masks at 40-or-45 kft,  and there's no pre-breathe requirement down to that 3.03 psia suit pressure level.  How can you lose?

GW

Last edited by GW Johnson (2024-04-20 10:27:20)

---

GW Johnson
McGregor,  Texas

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

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,181

Re: Large scale colonization ship

For GW Johnson...

I can't tell from your wording in Post #1469 if you approve of RobertDyck's planned atmosphere for Large Ship.

It seems to me you have provided historical perspective without addressing the issue at hand.... Would you fly in RobertDyck's ship, or not?

If not, why not?

(th)

GW Johnson

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From: McGregor, Texas USA

Registered: 2011-12-04

Posts: 5,459

Website

Re: Large scale colonization ship

I need to run the numbers,  but I think the Skylab 60% O2 at that 5 psia pressure violates the fire danger criterion.

If memory serves,  I think he was talking about 3 psia O2 + 5 psia N2 = 8 psia total.  That meets the hypoxia criteria leaked down,  and it stays OK with the fire danger criterion,  but it requires a min pure O2 suit pressure of 4.2 psia or higher to avoid pre-breathe requirements.  While quite adequate as a suit pressure,  it does make MCP suit designs much more difficult. 

GW

---

GW Johnson
McGregor,  Texas

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

RobertDyck

Moderator

From: Winnipeg, Canada

Registered: 2002-08-20

Posts: 7,811

Website

Re: Large scale colonization ship

Atmosphere specification, for large ship and Mars habitats:
2.7 psi O2
3.5 psi N2
1.148 psi Ar
Total: 7.348 psi total = 1/2 Earth atmospheric pressure at sea level

Spacesuit: 3.0 psi pure oxygen

If you want to increase suit pressure to 3.03 psi, sure! I wrote 2 significant figures, so I consider that to be within the fuzz factor (error margin, adjustment for individual suit, etc.)

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,181

Re: Large scale colonization ship

For GW Johnson....

Thanks for your preliminary review of RobertDyck's design.

On the assumption you have not read RobertDyck's writing on the subject, please look forward to his clarification.

He's written at great length about this, and he has done so multiple time.

It may be necessary for him to repeat all of that (or at least some of it).

Thanks for participating in the discussion.

(th)

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,181

Re: Large scale colonization ship

For RobertDyck...

you have a lot to worry about, in designing Large Ship.

Here comes ** one more ** worry...

https://www.yahoo.com/news/mutant-bacte … 55548.html

NASA has confirmed mutation of microbes on the ISS.

(th)

RobertDyck

Moderator

From: Winnipeg, Canada

Registered: 2002-08-20

Posts: 7,811

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Re: Large scale colonization ship

Cleanliness is an issue on all ships. As long as it isn't the Andromeda Strain.  (1969 movie reference).