On 10/20/2022 1:45 PM, pete...@gmail.com wrote:
> On Thursday, October 20, 2022 at 2:25:16 PM UTC-4, Lynn McGuire wrote:
>> On 10/19/2022 10:31 PM, peterw...@hotmail.com wrote:
>>> On Wednesday, October 19, 2022 at 1:03:04 AM UTC-5, peterw...@hotmail.com wrote:
>>>> On Tuesday, October 18, 2022 at 9:08:29 PM UTC-5, Lynn McGuire wrote:
>>>>> On 10/18/2022 2:52 PM, Lynn McGuire wrote:
>>>>>> "Artemis: A Novel" by Andy Weir
>>>>>> https://www.amazon.com/Artemis-Novel-Andy-Weir/dp/0553448145/
>>>>>>
>>>>>> A standalone science fiction book, no sequel or prequel that I know of.
>>>>>> I read the well printed and well bound trade paperback published by
>>>>>> Ballantine Books in 2018 that I bought new on Amazon. Hopefully there
>>>>>> will be a sequel some day.
>>>>>>
>>>>>> If you are looking for a hard science book, your book is here. The only
>>>>>> thing that I had a problem with is the low pressure 100% pure oxygen
>>>>>> atmosphere of the 2,000 person lunar colony, Artemis. I have a problem
>>>>>> with that but getting it to work might be doable, I just don't know.
>>>>>> Andy Weir actually wrote an article about the economics of a lunar
>>>>>> colony: "'The Martian' author Andy Weir solved moon economics to make
>>>>>> his new book 'Artemis' believable"
>>>>>>
>>>>>> https://www.businessinsider.com/andy-weir-artemis-moon-city-economics-the-martian-2017-11
>>>>>>
>>>>>> Jasmine Bashara moved to Artemis with her father from Saudi Arabia when
>>>>>> she was six years old, the legal minimum age. She grew up in Artemis
>>>>>> and is constantly on the edge of being evicted. She has a good heart
>>>>>> but is always looking for the easy way to get things accomplished. So
>>>>>> she lives on the shady side of Artemis and smuggles things in to make
>>>>>> extra cash. And her customers know that she can get almost anything for
>>>>>> them.
>>>>>>
>>>>>> The book is solid, I stayed up until 4 am last night reading it. I do
>>>>>> not understand why so many people do not like the book on Amazon. And
>>>>>> it makes me more than ever want to take a two week or four week trip to
>>>>>> the Moon. Once, a colony is established.
>>>>>>
>>>>>> My rating: 5 out of 5 stars
>>>>>> Amazon rating: 4.2 out of 5 stars (13,729 reviews)
>>>>>>
>>>>>> Lynn
>>>>> From a friend of mine: "Nitrogen is in short supply on the moon, and
>>>>> any recovered through mining would be reserved for growing plants. There
>>>>> are three nitrogen-free gas mixtures used for deep sea diving that do
>>>>> not contain nitrogen, but rely on helium, helium/hydrogen, or hydrogen
>>>>> to dilute the oxygen. I’,m not sure if any research has been done on use
>>>>> at sub-atmospheric pressures."
>>>>>
>>>>> "Helium and hydrogen have booth been found in lunar soils, but helium
>>>>> would be a poor candidate due to it’s ability to exfiltrate through the
>>>>> tiniest hole and through many materials. Hydrogen sounds like something
>>>>> the Soviets would have tried."
>>>>>
>>>>> So, 5 psia of pure O2 for a lunar colony is reasonable as a general
>>>>> atmosphere. I would have never thought so. The author does talk
>>>>> extensively about limiting usage of fire causing materials and many fire
>>>>> resistant / air blowout cubbyholes throughout the five domes.
>>>>> Incidentally, the lunar domes are half buried aluminum spheres many
>>>>> hundreds of meters in diameter with a double wall of six cm of aluminum
>>>>> each.
>>>>>
>>>> According to this NASA history, the Apollo spacecraft used a 5 psi oxygen
>>>> atmosphere in flight, so there is a good deal of practical experience with it:
>>>>
>>>> https://history.nasa.gov/SP-350/toc.html
>>>>
>>>> Quoting from an article from the National Air and Space Museum website,
>>>> written by senior curator Michael Neufeld, about the Gemini VI mission,
>>>> "To save weight, Mercury, Gemini, and Apollo spacecraft were designed to
>>>> operate at a cabin pressure of 5.5 lbs. per square inch of pure oxygen in space."
>>>> Any of these spacecraft would ascend through the perceptible atmosphere in
>>>> minutes, so the cabin pressure was rapidly bled down to maintain a 5 psi
>>>> pressure differential between inside and outside. If the crew were breathing
>>>> normal air at launch the drop in pressure could have caused decompression
>>>> sickness (commonly called the bends) as nitrogen gas came out of solution
>>>> in their blood and tissues. To prevent this, throughout the Mercury and Gemini
>>>> programs, at launch the cabin atmosphere was 100 percent oxygen, and the
>>>> crew were breathing pure oxygen long enough (several hours) to purge all
>>>> dissolved nitrogen from their bodies.
>>>>
>>>> After the Apollo One fire which killed three astronauts during a training
>>>> exercise this procedure was modified in a compromise between dangers.
>>>> Preflight atmosphere was changed to 60 percent oxygen and forty percent
>>>> nitrogen. The astronauts would breath 100 percent oxygen in their space
>>>> suits, sealed off from the cabin atmosphere, and would not remove their
>>>> helmets until cabin pressure was down to 5 psi. 60 percent oxygen was
>>>> much less of a fire risk than 100 percent oxygen, and was the lowest
>>>> percentage that would ensure that the cabin atmosphere would always
>>>> have a partial pressure of oxygen high enough to support human
>>>> consciousness. Astronauts would purge nitrogen as before.
>>>>
>>>> From Wikipedia:
>>>>
>>>> "The cabin atmosphere at launch was adjusted to 60% oxygen and
>>>> 40% nitrogen at sea-level pressure: 14.7 psi (101 kPa). During ascent
>>>> the cabin rapidly vented down to 5 psi (34 kPa), releasing approximately
>>>> 2/3 of the gas originally present at launch. The vent then closed and the
>>>> environmental control system maintained a nominal cabin pressure of
>>>> 5 psi (34 kPa) as the spacecraft continued into vacuum. The cabin was
>>>> then very slowly purged (vented to space and simultaneously replaced
>>>> with 100% oxygen), so the nitrogen concentration gradually fell off to zero
>>>> over the next day. Although the new cabin launch atmosphere was
>>>> significantly safer than 100% oxygen, it still contained almost three times
>>>> the amount of oxygen present in ordinary sea level air (20.9% oxygen).
>>>> This was necessary to ensure a sufficient partial pressure of oxygen
>>>> when the astronauts removed their helmets after reaching orbit.
>>>> (60% of five psi is three psi, compared to 60% of 14.7 psi (101 kPa)
>>>> which is 8.8 psi (61 kPa) at launch, and 20.9% of 14.7 psi (101 kPa)
>>>> which is 3.07 psi (21.2 kPa) in sea-level air.)[64]
>>>>
>>> Skylab was the first American space station, launched in 1973 using a
>>> Saturn 5 rocket left over from the Apollo program. The first two stages
>>> of the Saturn 5 could achieve low Earth orbit with a sufficiently small
>>> payload. In this case the payload was the essentially empty Saturn third
>>> stage with a pressurized crew compartment built into the hydrogen tank,
>>> a large solar cell array, a solar observatory, and other equipment.
>>>
>>> Skylab was pressurized to 5 psi with 70 percent oxygen and 30 percent
>>> nitrogen, for an oxygen partial pressure of 3.5 psi, similar to sea level
>>> on Earth. I have not heard of any problems resulting from this choice.
>>>
>>> Peter Wezeman
>>> anti-social Darwinist
>> It does seem to me that would be safer but, if there is ZERO nitrogen
>> available on the moon, would not be a good choice.
>>
>> And I still like that they do not have to prebreathe to go on a space
>> walk with pure O2.
>
> I'll just throw in that breathing 100% oxygen at sea level pressures will
> cause serious medical problems after 12 hours or so, and can be deadly
> in a day or two.
>
> pt

What about breathing almost pure oxygen at 5 psia for years on end ? I
am sure that there is a little CO2 in there, maybe 500 to 1,000 ppm.
And a few other trace gases at 1 to 10 ppm.

Thanks,
Lynn