Ammonia leak on board ISS

Trotter

News emerging of a leak on board the ISS. Could be an awkward fix involving an EVA I'd imagine. Chris Hadfield had been packing for the journey home but I'm sure this is engaging all the NASA minds tonight.

@Cmdr_Hadfield: Station's power relies on ammonia coolant. A few hours ago, we determined that the ammonia was leaking out of the Station and into space.

@Cmdr_Hadfield: It is a serious situation, but between crew and experts on the ground, it appears to have been stabilized. Tomorrow we find out for certain.

Audio of the report called in by Chris Hadfield available here..
http://www.nasa.gov/mission_pages/station/expeditions/expedition35/e35_050913.html

Trotter

EVA now live on http://www.nasa.gov/multimedia/nasatv/ustream.html

Capt'n Midnight

http://www.space.com/21059-space-station-cooling-system-explained-infographic.html

An ammonia pump on the main truss failed in 2010 and had to be replaced by spacewalking astronauts. The Expedition 35 crew on the International Space Station reported an ammonia leak near the same location on May 9, 2013.

Anchises

I think this might be a silly question


The ammonia that leaked turned to 'snowflakes' .

What is the science behind that ?

It is frozen in Space but it also has ZERO pressure.

As we've seen in various hollywood fiction presentations, in space one would suffer explosive expansion

So why would the ammonia not keep expanding to infinity or some molecular level - if there is no pressure ?




A.

Trotter

Im no physicist but once the liquid leaked out, it had X amount of time before it crystalises into flakes and becomes a solid due to the extreme low temperatures?

Capt'n Midnight

Anchises wrote: »

The ammonia that leaked turned to 'snowflakes' .

What is the science behind that ?

It is frozen in Space but it also has ZERO pressure.

As we've seen in various hollywood fiction presentations, in space one would suffer explosive expansion

You don't explode in space. The main thing to remember is to NOT hold your breath.

Liquids can only exist where the vapour pressure is lower than the atmospheric pressure. So ammonia on earth is normally a gas, but can be compressed into a liquid under pressure.

Freeze drying is when you get rid of ice by using a vacuum so the pressure is too low for water to exist.

Of course these gases only exist above the melting point of the solvent. Below the melting point it's still going to be a solid. Yes pressure can change the melting point (which is how ice skating works) but it's never by much.

In direct sunlight there is a lot of heat, behind the earth there is very little direct sunlight so it gets chilly , very chilly

Anchises

In direct sunlight there is a lot of heat.

So if there was an exposure to sun of the ammonia leak point, it would have expanded to a gas, and maybe not frozen ?

I think that's the question I have really - what does happen to a gas in Space with no pressure on it ? Does it infinitely expand attempting to fill space ?

(If I remember from my schooldays Boyle Law say that where the pressure is low expansion would occur)

A.

Capt'n Midnight

Anchises wrote: »

I think that's the question I have really - what does happen to a gas in Space with no pressure on it ? Does it infinitely expand attempting to fill space ?

more or less, in interstellar space you'll even find Hydrogen atoms as well as H2 molecules.

Of course gravity still attracts over long distances and there is the whole big bang asymmetry and the history of the universe to explain why its not evenly distributed.

At a local level the gravity of the sun / earth stop atoms whizzing off into space, though the energy from solar radiation , and coronal mass ejections and solar wind and all that mean that with enough time the lighter atoms like Hydrogen can reach escape velocity. Roll the clock back and Venus had oceans. Add enough hydrogen to convert the carbon dioxide in the atmosphere into water and you'd have enough for ~100m deep. The remaining nitrogen would be similar to what we have here. (yes it's more complicated than that since lots of oxides in the rocks but since sulfuric acid dissolves in water, terraforming Venus might be as simple as lots and lots of hydrogen.)



H + H -> H2 is the chemical reaction that gives off most energy per Kg