What is all this about a KILLER ICE BALL ?

[Bill Thmpson]

On 2003-02-10 15:39, DaveC wrote:
Besides, before we go off adding weight to the Shuttle fleet and seeking stronger glue, we may want to determine that tile displacement is indeed a problem. The tiles may have performed perfectly.

An article in this morning's Toronto Star (www.torontostar.com)covered some speculation that an ice ball may have formed at the wastewater vent and caused damage to the leading edge of the left wing when it broke free. Apparently this ice ball problem occurred at least once before (I think with Challenger in 1984) and the ice formed a basketball sized chunk. Heaters were installed after the incident to keep the vents from icing over but there may have been a failure. It's just one of many possible leads that needs to be investigated.


This interested me and I read the article in the TorontoStar. It seems like a convincing article because it seems to quote some NASA specialists.

Having said that, I have to say that it goes against what I have learned about Physics and I think a lot of scientists would agree with me. In High School Physics class, we put a glass of water into a class covered container and pumped the air out. At room temperature, the water boiled. Water, and Ice cannot exist in a vaccume.

But since this story seems to come from a reliable source and since it seems to back up its story with previous observations, I think we need to start a new thread of discussion abou this.

[Bill Thmpson]

TWO THREADS!? WOOPS, SORRY. I hope the web master can fix this.

/phpBB/images/smiles/icon_confused.gif

[Rue]

Do you mean that the ice would melt because of the water boiling in a vacuum?

I have seen this experiment done with a live fish in the glass and the fish will survive the "boiling."

[traztx]

On 2003-02-12 12:07, Bill Thompson wrote:
At room temperature, the water boiled. Water, and Ice cannot exist in a vaccume.


Therefore, it wasn't at room temperature.

[WHarris]

On 2003-02-12 12:07, Bill Thompson wrote:
In High School Physics class, we put a glass of water into a class covered container and pumped the air out. At room temperature, the water boiled. Water, and Ice cannot exist in a vaccume.


Ice can exist very well in a vacuum. Just take a look at comets, or moons such as Europa.

[Rue]

Are you refering tothis (http://purcell.phy.nau.edu/courses/02/spring/sci420/stuproj/webpages/sackey_sio/water.html)?

[Bill Thmpson]

On 2003-02-12 12:19, traztx wrote:


On 2003-02-12 12:07, Bill Thompson wrote:
At room temperature, the water boiled. Water, and Ice cannot exist in a vaccume.


Therefore, it wasn't at room temperature.


Yes, it boiled at room temperature. Without air water boils COLD. Is there something you are missing here? I know it is hard to imagine because we are used to water boiling only when it is hot. But it did boil cold and we even held the glass after the experiment was over and we took the glass out of the chamber.






<font size=-1>[ This Message was edited by: Bill Thompson on 2003-02-12 13:34 ]</font>

[Bill Thmpson]

On 2003-02-12 12:33, WHarris wrote:


On 2003-02-12 12:07, Bill Thompson wrote:
In High School Physics class, we put a glass of water into a class covered container and pumped the air out. At room temperature, the water boiled. Water, and Ice cannot exist in a vaccume.


Ice can exist very well in a vacuum. Just take a look at comets, or moons such as Europa.



Good point.

But does this mean a chunk of it can be in orbit around Earth? I may need to go to "The Mountain" to get this sorted out. I need to find someone with a more scientific background.

I know that liquid water cannot exist in a vaccume and when I was a kid, the general belief is that Mars' atmosphere, for instance, was too thin to keep water in a liquid state... it was either ice or vapor... not water.



<font size=-1>[ This Message was edited by: Bill Thompson on 2003-02-12 17:01 ]</font>

[Bill Thmpson]

On 2003-02-12 12:33, Rue wrote:
Are you refering tothis (http://purcell.phy.nau.edu/courses/02/spring/sci420/stuproj/webpages/sackey_sio/water.html)?


This looks exactly like the experiment in High School!!

[daver]

On 2003-02-12 13:29, Bill Thompson wrote:

But does this mean a chunk of it can be in orbit around Earth? I may need to go to "The Mountain" to get this sorted out. I need to find someone with a more scientific background.

<font size=-1>[ This Message was edited by: Bill Thompson on 2003-02-12 13:30 ]</font>


Well, it is thought that ice could exist in permanent shade at the poles of the moon. So if you could keep the sun off of it you could have ice in earth orbit. Or if you dumped a whole bunch of water out the vent and it froze and you reentered before it could sublime you could have ice for a short period of time.

[irony]

Aw, nuts... I was hoping for a thread more along the lines of "the comet is coming and we're all gonna die!" Must've been the way you capitalized the words 'killer ice ball.' /phpBB/images/smiles/icon_lol.gif

Don't mind me.

[TriangleMan]

On 2003-02-12 13:29, Bill Thompson wrote:

But does this mean a chunk of it can be in orbit around Earth? I may need to go to "The Mountain" to get this sorted out. I need to find someone with a more scientific background.

<font size=-1>[ This Message was edited by: Bill Thompson on 2003-02-12 13:30 ]</font>


The state that a substance is found in (solid, liquid or gas) is dependent on both the temperature and pressure. If there is no pressure and very cold temperatures, as in space, water is solid, but if you increase the temperature the ice will melt. Comets are a good example of this. Your high school experiment showed that at no pressure and average room temperature water will actually turn into vapour.

This principle is true for any substance. I think there was a thread recently about an extra-solar planet that was so close to the star that it was hypothezised to contain gaseous iron that would occasionally condense into molten iron 'rain'.

As for ice orbiting the Earth, I think it would have to be in a far orbit or else the heat radiating off the Earth would eventually vaporize it. That's purely speculation on my part though.

[TriangleMan]

Found a site that may be helpful in explaining that high school experiment:

http://www.sbu.ac.uk/water/phase.html

[calliarcale]

Chunks of ice can, indeed, exist in low Earth orbit. And they can form on the Shuttle's wastewater dump port. In fact, this actually happened on an early Discovery flight. The situation was detected by sensors reading abnormally high pressures in the wastewater line, so they took a peak with the RMS ("Canadarm") and saw a basketball-sized chunk of ice on the wastewater dump port. The RMS was used to literally bash the ice off, and all was well. To avoid a repeat, NASA installed heaters on the wastewater dump ports of all shuttles to keep the port from getting cold enough to let water freeze and build up around it.

There is some concern that ice may have built up around the port anyway and doomed Columbia. But a gentleman I know who works with the Space Shuttles on a regular basis at KSC said that the position of the wastewater dump port makes it highly unlikely that it was the cause of the accident; the port is high enough above the level of the wing that ice would seriously threaten the tiles on the left OMS pod, but not the wing.

Ice can exist in low Earth orbit. But not indefinitely. /phpBB/images/smiles/icon_wink.gif Solar heating will eventually take care of it.

[Bill Thmpson]

On 2003-02-12 14:19, TriangleMan wrote:
Found a site that may be helpful in explaining that high school experiment:

http://www.sbu.ac.uk/water/phase.html


Thank you. This clears things up very well.

[Bill Thmpson]

On 2003-02-12 16:51, calliarcale wrote:
Chunks of ice can, indeed, exist in low Earth orbit. And they can form on the Shuttle's wastewater dump port. In fact, this actually happened on an early Discovery flight. The situation was detected by sensors reading abnormally high pressures in the wastewater line, so they took a peak with the RMS ("Canadarm") and saw a basketball-sized chunk of ice on the wastewater dump port. The RMS was used to literally bash the ice off, and all was well. To avoid a repeat, NASA installed heaters on the wastewater dump ports of all shuttles to keep the port from getting cold enough to let water freeze and build up around it.



Minus your comment that it was unlikely that the ice could have doomed the space craft, your message is pretty much what the article in the Toronto Star said here (http://www.torontostar.com/NASApp/cs/ContentServer?pagename=thestar/Layout/Article_Type1&c=Article&cid=1035777609665&call_page=TS_News&call_pageid=968332188492&call_pagepath=News/News)

<font size=-1>[ This Message was edited by: Bill Thompson on 2003-02-12 17:14 ]</font>

[DaveC]

The thermodynamics behind ice forming in space from the wastewater are fairly simple. Unlike the lab experiment where water boils in a flask that is held under vacuum, in space there is no source of heat, other than the water itself (if it is shielded from the sun). For water to vaporize requires 540 calories per gram. As the vapour forms, the remaining liquid water cools down as it sheds heat to the vapor phase. For ice that is subliming into a vacuum, 620 calories per gram must be added.
The principle here is the same one used to cool the Apollo space suits. Water was sprayed into a sublimator through which ran the closed loop coils containing the suit cooling water (which ran through the suit next to the astronauts' bodies). Some of the water sprayed into the sublimator evaporated turning the rest into ice - which then removed heat from the coolant coils as it sublimed into the vacuum. One gram of ice subliming can cool 100 grams of water by over 6 Celsius degrees. Pretty efficient.

On Discovery, once the ice ball blocked any further flow of warm wastewater, it would have rapidly cooled to something near absolute zero as it lost heat to sublimation, assuming no supplementary heat source was available. Likely there would be some solar exposure, direct or indirect, plus some radiant heat from the shuttle itself. But ice is a pretty good reflecting surface, so it wouldn't have melted particularly quickly under radiant energy only. That's probably why the ice ball formed, even though it likely spent half its life in direct sunlight.

Had any of you put your hand on that vacuum flask with the boiling water, you would have noticed it getting colder.

[Rue]

Had any of you put your hand on that vacuum flask with the boiling water, you would have noticed it getting colder.


I have also seen this experiment done with a thermometer or an egg all of which would illustrate the behaviour of water in a vacuum.

[Lexx_Luthor]

Lost Moon, (J. Lovell & J. Kluger) page 114

When the spray of waste fluid vented from the side of the ship, it would crystallize on contact with space, forming an icy cloud of starry flecks that Wally Schirra, in one of his singular linguistic strokes, had dubbed the constellation Urion. If the cloud tonight was large enough and caught the sunlight just right, Saulietes believed he might be able to spot the spacecraft.
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Yeah, they showed that on the movie Apollo 13