Optimal air pressures.. - Which is best? More O2 or more pressure?

dicktice · 2003-05-25 13:31:56

RobertDyke: Thanks for the clarifications regarding inert gas content in air, and the effects of different pressures, for breathing. You mentioned growing plants.... Aside from atmospheric effects, how about weightless growing?
Remembering the "up-down" vibration approach claim to reduce or eliminate the need for centrifuging, to prevent loss of bone-mass in animals ... I had a serendipidous (i.e. baseless) mental image: of hydroponic plants on a vibrating, saturated-sponge platform. By applying vibration patterns that are unsymetrical in some way; sinusoidal on "top" and triangular underneath (say), or some other combination ... could this help the roots and stems somehow sort themselves out? Something other than simulating the gravity gradiant.
I know, it's crazy ... but take the idea further: Modulate the light intensity and/or polarization with the same vibration waveform. Alternatively, genetically adapt the intended plants, to store ferrite molecules (say) in their root cells, such that they will be weakly attracted to a sponge-supporting tray containing magnetizing field coils, fed with dc and/or or ac-modulation current.. Anything to prevent the roots and stems from snarling themselves into useless tangles. Anyone?

RobertDyck · 2003-05-25 17:13:27

RobertDyke: Thanks for the clarifications regarding inert gas content in air, and the effects of different pressures, for breathing. You mentioned growing plants.... Aside from atmospheric effects, how about weightless growing?
Remembering the "up-down" vibration approach claim to reduce or eliminate the need for centrifuging, to prevent loss of bone-mass in animals ... I had a serendipidous (i.e. baseless) mental image: of hydroponic plants on a vibrating, saturated-sponge platform. By applying vibration patterns that are unsymetrical in some way; sinusoidal on "top" and triangular underneath (say), or some other combination ... could this help the roots and stems somehow sort themselves out? Something other than simulating the gravity gradiant.
I know, it's crazy ... but take the idea further: Modulate the light intensity and/or polarization with the same vibration waveform. Alternatively, genetically adapt the intended plants, to store ferrite molecules (say) in their root cells, such that they will be weakly attracted to a sponge-supporting tray containing magnetizing field coils, fed with dc and/or or ac-modulation current.. Anything to prevent the roots and stems from snarling themselves into useless tangles. Anyone?

The vibration technique stimulates the nerves in human bones that regulate production of bone-building hormone. Bones are always adjusting themselves: one hormone dissolves bone, while another hormone builds bone. Normally the bone-building hormone is produced when bone nerves are stimulated by stress.

Plant seeds use gravity to orient themselves; stems grow "up" and roots grow "down" by gravity until the first leaves are formed, then stems/leaves grow toward the light and roots grow toward the water. I don't think vibration would solve the problem for plants as it does for humans.

Ferrite crystals in plant cells could be a novel solution. Could a static magnetic field replace gravity for plants with those crystals? It would increase the iron requirement for plant nutrition, but could be done.

I personally advocate a simpler system for life support on a spacecraft. The life support system I came up with uses in-vitro chloroplasts to create oxygen and complex carbohydrates for food. Some of that carbohydrate can be fed to yeast to produce protein, lipids, minerals, and the complete vitamin B complex. This would provide the basic staple, but not all human nutrition; it be augemented by dehydrated food. At least this would replace stored water, whole/wet food, and potatoes. Once on the surface of Mars, astronauts could deploy an inflated greenhouse that would use Mars atmosphere and Mars soil to grow crops. I think a greenhouse would be just too big for an interplanetary spacecraft in terms of mass, power, volume.

By the way, my last name is spelled "Dyck" and pronounced "Dick"; my name is not "Dyke".

dicktice · 2003-05-26 08:24:18

RobertDyke: I'm still not sure what to call you. My name is Richard (or Dick), by the way. Regarding dehydrated food: What if the "habitat" were a small, non-rotating spacecraft permanently orbiting e.g. between Earth and Mars, with no access to to dehydrated plants grown elsewhere, under Earth-like conditions...? Then, the problems you avoid by waiting until you arrive on Mars, will have to be faced in weightless space. I just wanted to pursue the problem of how plants from Earth might be made to "function" under these circumstances.

RobertDyck · 2003-05-26 09:36:01

RobertDyke: I'm still not sure what to call you. My name is Richard (or Dick), by the way.

My on-line name is "RobertDyck" and my real name is "Robert Dyck". My friends call me Rob. Pick one of those 3, but please don't call my "Dyke". There are already too many people from America and the Canadian provinces of Ontario and Alberta who mispronounce my name.

I am envisioning a mission very similar to Mars Direct as the first manned mission to Mars. There are several advantages of this mission plan: get on the surface of Mars quickly where you have an atmosphere to protect from micrometeoroids and radiation, gravity (although only 38% of Earth), and resources to harvest for fuel for the return trip and life support. For colonization we could use a permanent shuttle to go between high Earth orbit and high Mars orbit, with aerocapture at each planet for orbital insertion. A permanent shuttle will require more fuel than a cycler, but the surface shuttles (Earth and Mars) will require a lot less fuel. Such a permanent shuttle will have to be refuelled before each trip anyway, so it could be stocked with dehydrated stored food. I feel that if you want something large enough for an on-board greenhouse, you might as well spin it for artificial gravity.

However, you are not the only one who wants to examine the issue of a greenhouse in space. The University of Guelph wants to build a greenhouse on the ISS. I think a greenhouse is so big it will never be built; after all, science is being cut back on the ISS so there is not much possibility of a new major module. However, research into a greenhouse in space is a part of the Advanced Life Support project at NASA's Johnson Space Center, the University of Guelph (they presented the 2 papers I mentioned), and that plant genetics researcher I mentioned who grew alpine plants in a hypobaric chamber.

To support your research, one pea plant mutation has extra tendrils and no leaves at all. Chloroplasts in the tendrils perform photosynthesis, and the open space between tendrils permits light to penetrate. This permits 3 dimensional packing so pea plants with this mutation grow shorter but still produce as much peas. Since tangled foliage for this mutation is desired, it may be applicable to space.

dicktice · 2003-05-27 17:08:15

Okay: Me, Dick...you, Rob.
Very interesting stuff, you contribute ... and I'm following you closely regarding the details about pea-plant mutations in your last paragraph. But before going into that, which seems pretty far along the way towards practical crop testing, I'd like to pursue my initial (vibration) theme a bit further, with your indulgence:
The vibration waveform fed to the platform driver would be on during germination only, to stimulate (?) the root tendriles to separate from the stem tendrils inside individual tubes, after which the stems would grow towards the light, and the roots in the other direction. When the stems emerge from their tube-ends the developing leaves would continue in the direction of the light, while the roots get all tangled together when they emerge from the opposite ends. The reason for the pogostick acceleration is to stimulate whatever it is in germinated seedlings, to grow initially in opposite directions. I imagined very slow, high amplitude accelerations, to simulate gravity impulses at the "bottom" of ach stroke, and something approaching freefall at the "top." Then I decreased the amplitude while increasing the frequency, until the motion no longer could be thought of as acceleration, but vibration. This could be tried out horizontally, here on Earth, I imagine. Root crops as well as pea and bea crops ... but peanuts perhaps should be puit on hold for a while.... Cute, eh?

RobertDyck · 2003-05-29 15:31:37

I just wonder how vibration would cause seedlings to discern up from down. But it may work. I would like to say "try it" but that experiment really requires the zero-gravity (microgravity) of space. Seed germination would be an excellent experiment for the ISS or Shuttle. Has something like this already been done? I remember seeing a picture of an astronaut with a rack of germinated plants on the Shuttle. Try a search of experiments already conducted.

dicktice · 2003-05-29 15:56:22

Well, Rob ... let's skip it about microgravity plant growth, at least for the time being, because there's lots more to discuss regarding life support systems. I'm in the process of reading your (fact) discussions regarding growing plants on Mars. Semi-seriously, I'm intrigued by the thought of Pacific Redwood seeds growing beneath light transmitting roofed over canyon tributaries, for example. Talk about really high up treehouses...!

sethmckiness · 2003-08-23 08:02:40

Also, Of the 21% Oxygen we breath in, we only use 6% of it. Otherwise CPR wouldn't work, just something to throw out there.

cuhhriss · 2005-04-19 18:12:54

hey . so whats ur theory of bringring oxygen up to mars and getting the co2 off?

orionblade · 2006-10-24 12:07:04

believe it or not, it's not nerve stimulation that causes bone building... it's the piezo-electric effect. Same thing works on dental braces: pull back on the tooth and it leverages against the enclosing jaw bone tissue, inducing a tiny voltage differential across the faces of the bone - the osteoclasts and osteoblasts detect this voltage and alter their activity in the regions of altered potential - the bone gets chewed away on the compressed side of things, and redeposited elsewhere. Take the pressure away and apply a voltage, the same thing happens.

Yay for bioelectrics and finally taking grad classes.

It's been over 2 years since I posted here...

I'm now finishing up my BS in Biology with a minor in Chem. Only problem is I forgot to take a few classes like Dance and it's Audience, and Sociology.

Like gee whiz. I did, however, take ballroom... man that was fun!

Hopefully this topic isn't woefully dead and unread.

Rion

dicktice · 2007-02-11 19:50:57

I'm replying here just to ensure that the two threads discussed in the above posts from a few years back are kept current, ie: those of optimum space greenhouse pressure (re. RobS) and bone regeneration (re. orionblade) won't be neglected, since they are of such importance to the long voyages--distancewise as well as timewise--now being discussed elsewhere....

m1omg · 2007-07-06 04:59:04

Also, Of the 21% Oxygen we breath in, we only use 6% of it. Otherwise CPR wouldn't work, just something to throw out there.

You will faint in a 6 percent oxygen content 1 bar atmisphere.

SpaceNut · 2007-08-10 22:08:18

This quote is from the mining collapse articles from Utah...

"Normal oxygen is 21 percent," he said. "Once you get down to 15 percent you start having effects, and at 7 1/2 percent, it would not support life very long."

bolbuyk · 2007-09-09 12:45:51

Maybe a pressure of about 50kPa, 40% O2, 40% He and 20% N2 would be a rather good atmosphere.

Terraformer · 2007-09-15 11:13:59

Maybe a pressure of about 50kPa, 40% O2, 40% He and 20% N2 would be a rather good atmosphere.

40% helium?!?!

*squeaks* Hi everybody, how are you today?

louis · 2008-03-30 07:29:21

I think the problem of explosive decompression is one of the reasons for having inflatable habitats entrenched and covered in regolith. In those circumstances if there is a break in the pressure seal there won't be an explosive decompression. I don't know how quickly there would be decompression - but if it was sixty seconds say then there would be time to get into emergency safe cabinets three or four of which might be placed around the habitat and which would include a couple of hours air supply. . Of course, this might be an argument for always having one person on duty in the main lander so that they are then able to go and rescue people trapped in the safe cabinets (which might involve wheeling them back to the lander air lock).

SpaceNut · 2020-01-26 19:08:31

Here is one of the partial pressure oxygen content atmosphere for man to breath on mars.

need to fix artifacts

elderflower · 2020-01-28 16:04:05

Bolbuyk probably should have said Argon rather than Helium. It has about the same abundance in Mars atmosphere as Nitrogen and would be just as good as a buffer gas.
The low partial pressure of nitrogen, though, might make life difficult for nitrogen fixing bacteria, and we are heavily dependent on these, particularly where we don't have industrial nitric acid or urea plants.

SpaceNut · 2020-01-28 18:11:51

We have some data for mixes from deep sea diving but we have little for how little nitrogen we can get away with other than for fire control conditions.

RobertDyck · 2020-01-29 01:34:40

Atmosphere of Earth contains 0.9340% argon.
Earth's atmosphere by volume, excluding water vapour. Lower pie chart is trace gasses.
Data for CO2 and methane are of April 2019.

JohnX · 2020-01-31 15:41:34

elderflower wrote:

Bolbuyk probably should have said Argon rather than Helium. It has about the same abundance in Mars atmosphere as Nitrogen and would be just as good as a buffer gas.
The low partial pressure of nitrogen, though, might make life difficult for nitrogen fixing bacteria, and we are heavily dependent on these, particularly where we don't have industrial nitric acid or urea plants.

There was a post way back in this topic with the idea that hydroponics would provide the nitrogen in the aqueous solution used. That would allow Argon to be used, not He (not available) or N2 (avoid the bends).

tahanson43206 · 2020-02-15 07:40:12

For SpaceNut re topic ...

I'd like to bring this topic back into view to see if forum members might be interested in developing it a bit more. The recent discussion of the idea of creating a greenhouse at full Earth normal pressure (14.7 psi), using only Martian atmosphere for input (by compression without filtering) turned out disappointing with respect to the original question, but definitely rewarding in terms of research uncovered and insights posted.

In recent days, I ran across a discussion (in StackExchange) about why the Russians, Americans, Europeans and Japanese all agreed upon using Earth normal atmosphere in the ISS .... The primary factor (apparently) was the risk of fire.

Downsides are numerous, but the use of Nitrogen as the inert gas filler is the most serious, because of the risk of bends if/when pressure is decreased. A typical example of when this is a problem is when an astronaut dons a space suit that runs at a much lower pressure.

I am interested in encouraging a consensus among forum participants in the My Hacienda virtual Mars community.

My Hacienda has not yet taken off as a going enterprise, but here and there I see signs the concept is beginning to take root.

Each Hacienda operator will be responsible for managing the mixture of gasses, pressure settings and other variables related to the interior environment of the habitat sections. It seems likely to me there can exist differences from habitat to habitat, just as there will surely be architectural differences, but some consistency across the community might facilitate movement of people and goods between Haciendas.

In addition, there will be common places such as those described by Louis when he has been in an expansive mood, which happily has occurred frequently over the years.

I looked at the Periodic Table on my wall a few minutes ago, while preparing for this post, and noted that Argon has a very nice attribute that makes it attractive as a substitute for Nitrogen as a filler gas ... Unlike Helium, which has a lower atomic weight than Nitrogen and causes speech to be elevated in tone (or so I have read), Argon has an atomic weight only slightly greater than Nitrogen, so I would expect a minimal impact upon human speech or sound quality in general.

Invitation for Contribution:

I am hoping other forum members will expand a bit upon this topic, with a focus upon the shared environment each of us will have in the My Hacienda virtual community. At this point, I am inclined toward a 14.7 psi default pressure for habitat structures underground, with Argon as the preferred inert gas.

Default temperature would be on the order of 21 degrees Celsius.

(th)

SpaceNut · 2020-02-15 08:36:11

Argon is where I think Robertdyck had suggested a while ago but in either case Atmospheric compensation post of how to get back air for internal use

kbd512 · 2020-02-15 17:47:42

tahanson43206,

Using Argon as an inert buffer gas has already been done here on Earth for deep sea diving. It will still distort human speech, but it'll be easier to understand than speech distorted by buffer gases that increase the pitch of the sounds that human vocal cords generate. In the end, an atmosphere with "sea level" or "mile high" equivalent pressure altitude works best.

tahanson43206 · 2020-02-15 18:25:02

For kbd512 re #49

Thank you for the tip regarding Argon already tested for deep sea diving.

I am intrigued by the idea that speech might be impacted, so I'll pursue the lead!

Since the speed of sound is impacted by the lower atomic weight of Helium, I would expect the speed of sound in a mix using Argon to be relatively close to the mix using Nitrogen, since the atomic weights are similar. However, as so often happens as a result of discussions in the NewMars forum, I expect to learn something as the topic proceeds.

The only reason I can think of right now (off the top) is that perhaps the bonding of Nitrogen into molecules of 2 atoms may yield an atomic weight for the molecule which is greater that that of Argon, which (I expect to learn) exists as molecules of one atom each.

However, on to Mr. Google to find out!

Edit#1: Asking for the atomic weight of Dinitrogen:

Nitrogen/Atomic mass
14.0067 u

Edit#2: Asking for the atomic weight of Argon:

Argon/Atomic mass
39.948 u

Asking for the speed of sound in Argon, received this MIT list:

Speed of Sound in Various Gases
Gas Speed of Sound (m/s)
Argon 319
Helium 1007
Krypton 221
Xenon 178
8 more rows
Speed of Sound in Various Gases - Pages.mtu.edu

For reference, the speed of sound in air is:

The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium. At 20 °C (68 °F), the speed of sound in air is about 343 metres per second (1,235 km/h; 1,125 ft/s; 767 mph; 667 kn), or a kilometre in 2.9 s or a mile in 4.7 s.
Sound energy density: w
Sound pressure: p, SPL,LPA
Sound energy: W
Sound power: P, SWL, LWA
Speed of sound - Wikipedia
en.wikipedia.org › wiki › Speed_of_sound

So the speed of sound in Argon gas is just slightly less than the (about) speed of sound in air.

What may not be available is the speed of sound in a mixture substituting Argon for Nitrogen.

Asking for deep sea gas mixture using Argon:

Argox is the informal name for a scuba diving breathing gas consisting of argon and oxygen. Occasionally the term argonox has been used to mean the same mix. The blend may consist of varying fractions of argon and oxygen, depending on its intended use.
Argox - Wikipedia

Edit #3: Here is a patent on use of Neon for deep sea diving:

Crude neon with nitrogen and oxygen as a hyperbaric intervention breathing mixture
Abstract
Embodiments of the present invention provide systems, methods and apparatus for to using crude neon with oxygen and nitrogen as a hyperbaric intervention breathing mixture. Embodiments include providing a work environment under pressure; performing work operations within the pressurized work environment; and providing a breathing mixture created from crude neon and oxygen as a hyperbaric intervention breathing gas. Numerous additional aspects are disclosed.

Well! So much for Argon, it would appear ... at least for use as a deep see mixture:

https://en.wikipedia.org/wiki/Breathing_gas

Many gases are not suitable for use in diving breathing gases.[5][25] Here is an incomplete list of gases commonly present in a diving environment:
Argon
Argon (Ar) is an inert gas that is more narcotic than nitrogen, so is not generally suitable as a diving breathing gas.[26] Argox is used for decompression research.[1][3][27][28] It is sometimes used for dry suit inflation by divers whose primary breathing gas is helium-based, because of argon's good thermal insulation properties. Argon is more expensive than air or oxygen, but considerably less expensive than helium. Argon is a component of natural air, and constitutes 0.934% by volume of the Earth's atmosphere.[29]

Edit#4: This Russian study gave results which I find mildly confusing. On one hand, it appears that subjects working with an Argon gas mixture did better, and on the other hand, studies of Argon in mice appeared to show problems with narcosis.

Perhaps there is a mixture which would include Argon that would NOT be harmful to humans at normal (14.7 psi) pressure.

Since Nitrogen is in short supply at Mars, it would appear sensible to consider Argon as a part of the inert fraction of a "normal" gas mixture for human habitation.

(th)

Last edited by tahanson43206 (2020-02-15 18:53:33)

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#26 2003-05-25 13:31:56

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#27 2003-05-25 17:13:27

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#28 2003-05-26 08:24:18

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#29 2003-05-26 09:36:01

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#30 2003-05-27 17:08:15

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#31 2003-05-29 15:31:37

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#32 2003-05-29 15:56:22

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#33 2003-08-23 08:02:40

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#34 2005-04-19 18:12:54

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#35 2006-10-24 12:07:04

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#36 2007-02-11 19:50:57

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#37 2007-07-06 04:59:04

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#38 2007-08-10 22:08:18

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#39 2007-09-09 12:45:51

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#40 2007-09-15 11:13:59

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#41 2008-03-30 07:29:21

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#42 2020-01-26 19:08:31

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#43 2020-01-28 16:04:05

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#44 2020-01-28 18:11:51

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#45 2020-01-29 01:34:40

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#46 2020-01-31 15:41:34

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#47 2020-02-15 07:40:12

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#48 2020-02-15 08:36:11

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#49 2020-02-15 17:47:42

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

#50 2020-02-15 18:25:02

Re: Optimal air pressures.. - Which is best? More O2 or more pressure?

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