Water in space

[jhoblik]

What will be status of water on the Earth orbit, just protected by ruber bag(or something similar). It will be liquid or solid or gas form. Is it posible to control status by color of bag.

 

[CalliArcale]

I guess it would depend on how much pressure you've got it under, and whether or not it's in a shadow. If it's under enough pressure to keep it from boiling off, and on the Earth's nightside for a long period of time, then it will freeze solid. It'll melt in the sunlight, though. Whether or not it comes to a boil will depend on how much pressure its under. <br /><br />EDIT: yes, the color of the bag is significant. A white bag will tend to reflect heat, and could keep the water frozen longer. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[nacnud]

Ok lets say a water ballon at EML1

 

[jhoblik]

I would like to know, what will happen bag of water in space, no presure, just ability to change color of cover.Is it posible to keep it in a liquid form(no presure just space).

 

[henryhallam]

Can the bag be elastic (like a rubber balloon) in order to keep the water under pressure? If not, it is impossible. Refer to the first diagram on this page. It shows the state of matter that water is in for a given temperature and pressure. Green is liquid water, grey is steam / water vapour, and the various blues are ice with different crystal structures.<br /><br />If the bag is not elastic and not rigid, then its contents must be at the same pressure as outside, i.e. a vacuum or 0 Pa. Liquid water (green on the diagram) can only exist above about 1000Pa, which is around 1% of sea-level atmospheric pressure. So depending on the temperature (which can be regulated within reasonable limits by changing the colour of the bag) it will either be ice or steam/water vapour.<br /><br />If on the other hand you allow the bag to be elastic like a balloon then you can keep the water under a certain amount of pressure. A full atmosphere of pressure would require a very tough balloon, but 10000Pa or 10% of atmospheric pressure ought to be pretty easy, maybe even possible with an ordinary water balloon. It seems reasonable that by painting it the right colour and giving it a spin to "barbecue it evenly" à la Apollo PTC you could keep it within the right temperature range and it would stay liquid.

 

[krrr]

Is there some material which gets bright when it's hot and dark when it's cold? Would be perfect for heat regulation in a spacecraft.

 

[nacnud]

Well everything dose, look up black body radiation, but not to the extra you want. Perhaps a phase change material might work?

 

[scottb50]

I think it would be much simpler to keep water liquid and at the same pressure the rest of the vessel is at. If you store water externally I would think the more solid the better, use heaters to retrieve water when needed.<br /><br />Fairly simple shielding would be all you need. <div class="Discussion_UserSignature"> </div>