Chinese Team Heading for Coldest Spot on Earth

LMCBoy writes "Dome A is the highest point on the Antarctic Plateau, and it has never been reached by humans. It is thought to be the coldest place on earth, and is certainly among the most remote. Yesterday, a team of Chinese explorers set out from Fremantle, Australia to reach Dome A and set up a robotic weather station which will monitor the local conditions for up to five years. The team is expected to arrive at Dome A in early 2005."

User error

[XipX]

I quote

A 12-man Chinese expedition will leave Shanghai for Antarctica on October 25, targeting the highest polar icecap peak- 4,039 meters above sea level

Re:Question

[Anonymous Coward]

That is actually not a bad question but I think you'll find that the breathing reflex is not affected by the composition of the air in the environment - rather, it is related to the carbon dioxide concentration in the blood. The carbon dioxide is created within the body as a by-product of aerobic respiration. If that carbon dioxide is freezing before they have the chance to expel it, they wouldn't be needing a breathing reflex anyway.

the same story few weeks ago

[helfen]

http://science.slashdot.org/article.pl?sid=04/10/2 9/1341212&tid=134 [slashdot.org]

Re:Excellent teamwork

[Anonymous Coward]

I helped design those weather stations, we use 148 Saft Lithium-thionyl chloride (Li-SOCl2) 20 AHr batteries. The weather station averages about 1 mA at 12 V. The batteries aer burries in the snow about 3 m where we expect the temperature to be about -65 C.

We cannot find any batteries that could be recharged at this temperature, Li-SOCl2 batteries are the only option. We also have solar pannels for the summer months. Without the solar pannels the station should last 5 years, with the pannels we might get 7-10 years, and 20 years of data for summer.

The trick with getting things working at that temperatures was testing, we find that most things work (chips etc) but we test all the parts here first.

Peter Jansen
Australian Antarctic Division

They're going to visit a lab in Finland?

[bitingduck]

The coldest spot on earth is in a laboratory in Finland:

http://boojum.hut.fi/Low-Temp-Record.html [boojum.hut.fi]

Dome A is the coldest naturally occuring spot.

Here's a clue

[serps]

There's a Free Trade Agreement [dfat.gov.au] in the pipeline.

How to make Dry Ice - It appears...

[DAldredge]

It appears that it takes liquid CO2 to make dry ice.

From a google search.

Basically, dry ice is frozen carbon dioxide (CO2). CO2 is usually found as a gas -- it's what we exhale. To make dry ice, CO2 is compressed, and it liquefies at a pressure of approximately 870 pounds per square inch. The dry ice press then reduces the pressure, and part of the liquid CO2 sublimates (meaning it turns from a solid into a gas). The remaining liquid freezes into flakes that are compacted into solid blocks. The resulting dry ice is denser, heavier, and colder than ice made from water.

Here is a link to a machine that can make a block of dry ice in 60 seconds with just a liquid CO2 cylinder, and it costs less than 600 USD.

http://www.amer-rest-equip.com/usare_polfo_dry_ice _makers.html [amer-rest-equip.com]

Not an issue

[tanveer1979]

They are going there in Early 2005, and that peak summer in antartica. So temparatures will not be dropping below -50C. :)

Re:Question

[Aglassis]

You said: "So what happens when the temperature (down to -90C) goes below the sublimation temperature of CO2 (-76C, if I recall correctly)? Does it just freeze out of the air?"

Most likely. The phase diagram [www.acri.fr] for CO2 shows that for our standard atmospheric pressure, CO2 freezes at -78.5 C [uakron.edu]. If the temperature is only slightly lower than -78.5 C it may take some time for a significant amount of CO2 to precipitate due to the latent heat of solidification for CO2 of -43 cal/g (smaller than the absolute value of water which is about -80 cal/g) . Additionally some CO2 may remain in the air which varies by temperature (which would be relative humidity [wikipedia.org] for water). As the temperature drops the amount of CO2 that can be dissolved in air decreases. Unfortunately I couldn't find a reference for CO2 saturation vs temperature. If it is reasonably low (which it should be) at -90 C, CO2 frost will develop.

On Mars with an atmospheric pressure that varies from about 5 - 10 mbar (1 atm = 1013.25 millibars), CO2 frost can develop as seen [uoregon.edu] by Viking 2 and by satellite pictures [msss.com] of the poles. Snowflakes [exo.net] won't form, since the shape of a snowflake is determined by van der Waals forces (don't occur in CO2). CO2 frost should look similar to this [usda.gov].

Re:Question

[Xetrov]

Thermal imaging from satellites?

Re:How to make Dry Ice - It appears...

[Anonymous Coward]

"Dude, it was liquid CO2.. there is no question of that."

There is a valid question of your results because they contradict scientific experiments. The triple point of CO2 is -57 C at 5 atm. For dry ice to form the temperature must be -80 C. By shaking it around you may have warmed it up, subliming some CO2 and increasing the pressure. Since 5 atm (absolute) is about 60 psi (gauge pressure), its unlikely that your bottle could have supported that much pressure. Your bottle probably could not support 20 psi (which would be equivalent to a force on the cap of about 15 lbs--You can test this, hold a bottle upside down, drill a hole in the cap and attach a 15 lb barbell. See if it holds). You most likely saw water condensation (from the air in the bottle) or melting (from water that was part of the dry ice).

Re:Question

[The Bender]

CO2 has a vapour pressure of ~400 Torr at -90 C, and a partial pressure of only 25 Torr in air, so unfortunately it won't freeze out. For that to happen, the temperature would have to go down to about -115 C. Sorry.

RTG defined

[bruckie]

RTG = Radioisotopic Thermoelectric Generator

See this site [thefreedictionary.com] for more info.

--Bruce