Posted on 07/10/2018 2:01:41 PM PDT by BenLurkin
In the new study, the researchers dropped the full experimental set up for photocatalysis down a 120m drop tower, creating an environment similar to microgravity. As objects accelerate towards Earth in free fall, the effect of gravity diminishes as forces exerted by gravity are cancelled out by equal and opposite forces due to the acceleration. This is opposite to the G forces experienced by astronauts and fighter pilots as they accelerate in their aircraft.
The researchers managed to show that it is indeed possible to split water in this environment. However, as water is split to create gas, bubbles form. Getting rid of bubbles from the the catalyst material once formed is important—bubbles hinder the process of creating gas. On Earth, gravity makes the bubbles automatically float to the surface (the water near the surface is denser than the bubbles, which makes them buyonant)—freeing the space on the catalyst for the next bubble to be produced
In zero gravity this is not possible and the bubble will remain on or near the catalyst. However, the scientists adjusted the shape of nanoscale features in the catalyst by creating pyramid-shaped zones where the bubble could easily disengage from the tip and float off into the medium.
But one problem remains. In the absence of gravity, the bubbles will remain in the liquid—even though they have been forced away from the catalyst itself. Gravity allows for the gases to easily escape from the liquid, which is critical for using the pure hydrogen and oxygen. Without the presence of gravity, no gas bubbles float to the surface and separate from the mixture—instead all the gas remains to create a foam.
(Excerpt) Read more at scientificamerican.com ...
“buyonant”
“the the”
I remember when the Scientific American was a great science magazine. Now, it could use a little proofreading by someone who speaks English.
How much sun/star light are you going to get when you’re halfway to Alpha Centauri? Better bring some Duracells.
You don’t “make oxygen from water.”
A molecule of water is an oxygen atom bonded to two hydrogen atoms.
You can break the bonds of two water molecules and get an O2 molecule and 2 H2 molecules, but the oxygen already existed and was not made, which would require a nuclear reaction.
Use a centrifuge.
Might work with sparkling water. Still heavy as hell, though.
The inverse-square law for radiation dictates that the intensity of light is inversely proportional to the square of the distance from the source of that that light.
So, if you double the distance from the sun you will have ¼ the sunlight. If you triple the distance from the sun you will have 1/9 the sunlight.
Once they pass Mars I don’t think their Solar Oxygen Generator is going to work very well.
And the problem of the weight to carry enough water for water needs and to convert it to Oxygen??
70 gallons of water at room temp weighs about 600 pounds. And how many gallons of water would a long distance space vehicle have to carry - for water and for oxygen?? So their is a weight issue.
Then at what temperature will it be kept. If a gallon of water is not kept warm in a space vehicle it could freeze. Then you have a different problem. A gallon of water turned to ice has more volume than it had as water - it needs more room. The practical implication of that adds to the size of the vehcile needed.
Then whether the weight of the water or the mass of the ship large enough to carry it, you have a question of the additional energy meeded to lift and propel a ship that can carry all that water in space. That requirement has to be considered also.
Splitting the atoms may actually turn out to be the easier thing to do than the practicality of employing it for spaceflight.
I don’t get the suspense.
Make the foam in 0-gee, move the container to a centrifugr. Or just accelerate it and pull it back like a pump.
Sure is a lot of propaganda in SA these days. Remember when it was a solid ecience mag.
On the other hand, carried water has the flexibility to be used as radiation shielding (reducing net weight), can help with thermal regulation (reducing energy requirements), as well as be used for life-support both as water and by carrying oxygen in a denser from which requires much less in the form of pressure tanks (again, reducing weight).
So the practical solutions can and will add your suggesttions into the mix and MAYBE offsetting somewhat the “extra-load-carrying” factors of stored water.
However, in doing so, a consideration will need to be how any use of water that you suggested will be diminished by the need for the same water for other uses. Suggesting it can for instance be part of shielding has to consider how the uses of the same water for other needs will diminish the shielding over time or need to be offset by other means as the water is consumed for those other needs. That opens the question as to other materials providing equal or better shiedling than water, but weighing less than water for the same amount of shielding.
No single aspect of “soltion” can be considered in isolation of all the varilable surrounding the use of something.
I still see these practicalities as what I think will find more research put into them than the research that found out how to slit the water atoms.
In part, I think someone will like the idea of doing the water-atom splitting for obtaining oxygen for long term space travel, and will imagine a very sophisticated “biosphere affair within the space ship” where water is always circulating, being used, being broken down, and being reconstituted in biolgioal mechanisms (bacteria) that rejoin free oxygen and hydrohen back into water. I think it might be sort of like a mini-biosphere-environment sealed within the external walls of the ship. It might even have “rain”. clouds and open resevoirs with artifical sunlight assisting in evaporation from which to capture water.
A Star Ship would have unlimited nuclear power.
Just a hint, take 0.0000000000001% of that energy and split water. However, you will not win research grants.
“Use a centrifuge.”
spin the drum ...
And yes, water must be kept liquid. But so must the crew - and a big tank of water would make an excellent heat buffer to smooth out variations in temperature.
Getting the bubbles out is easy - you need only a very small difference in weight, and you can do that with a turntable.
The big problem is the energy needed to split the water into H2 and O2, and yes, as has been pointed out, no way will there be enough energy in starlight.
I forget - dont the different gasses go to opposite electrodes (+/-) ??
So even if the bubbles dont rise, a constant flow of water from each separate electrode into a mesh filter (catching the respective bubbles) should work.
no?
centrifuge motion (someone else mentioned) also should separate gas from liquid
“And since oxygen gas must be kept in pressurized tanks”
HEAVY metal/plastic tanks the higher the pressure goes (or bulky low pressure)
as long as you have the power source (solarcell efficiency has been going up ...)
Seems to me that keeping the water in a liquid state would require more energy than you could produce.
A good point. However, if the water started out liquid at takeoff, all you would need is good insulation, plus a *very very small* feed of energy from the rocket motors.
That presumes Earth-sourced water, doesn’t it? The shuttle’s max payload would have been about 6,500 gallons of water. How much would be needed?
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