Lots of Pure Water Ice At Mars North Pole 176
brink2012 writes "Planum Boreum, Mars' north polar cap contains water ice 'of a very high degree of purity,' according to an international study. Using radar data from the SHARAD (SHAllow RADar) instrument on board the Mars Reconnaissance Orbiter (MRO), French researchers say the data point to 95 percent purity in the polar ice cap. The north polar cap is a dome of layered, icy materials, similar to the large ice caps in Greenland and Antarctica, consisting of layered deposits, with mostly ice and a small amount of dust. Combined, the north and south polar ice caps are believed to hold the equivalent of two to three million cubic kilometers (0.47-0.72 million cu. miles) of ice, making it roughly 100 times more than the total volume of North America's Great Lakes, which is 22,684 cu. kms (5,439 miles).
The study was done by researchers at France's National Institute of Sciences of the Universe (Insu), using the Italian built SHARAD radar sounder on the US built MRO. SHARAD looks for liquid or frozen water in the first few hundreds of feet (up to 1 kilometer) of Mars' crust by using subsurface sounding. It can detect liquid water and profile ice.
Mars southern polar cap was once thought to be carbon dioxide ice, but ESA's Mars Express confirmed that it is composed of a mixture of water and carbon dioxide.
The study on Mars north polar cap appears in the journal Geophysical Research Letters, published by the American Geophysical Union."
Re:What is the volume? (Score:5, Informative)
The salty Caspian Sea is the world's largest land-locked body of water. It contains approximately 18,900 cubic miles of water (78,700 cubic kilometers).
Lake Baikal is the world's largest freshwater lake in terms of volume. It contains about 5521 cubic miles of water (23,000 cubic kilometers), or approximately 20% of Earth's fresh surface water. This is a volume of water approximately equivalent to all five of the North American Great Lakes combined.
Re:Look at that bottled water opportunity! (Score:5, Informative)
Still cheaper than a liter of printer ink.
Ocean Equivalent (Score:5, Informative)
Since Mars's Surface Area = 144 million km^2, this implies (for 2.5 million km^3 of ice) that ice caps are enough to supply a water layer 17 meters deep over the entire surface, or maybe 50 meters deep in Hellas and the Northern lowlands, if it was all melted. (If the polar caps entirely melted, that alone would raise the surface pressure above the triple point of water, so liquid water would be possible. The Hellas Basin is deep enough that the pressure is above the triple point now, and it definitely could have liquid water in it if the climate warmed some.)
Note that the polar caps show very clear signs [arizona.edu] of layering [arizona.edu], presumably caused by the long period obliquity oscillations [obspm.fr], and are in general very young geologically, so it is not beyond belief that, say, the Hellas basin fills up with water on a regular basis, every 500,000 years or so.
Re:Bunk (Score:4, Informative)
Re:Oil (Score:2, Informative)
Saturn's moon Titan.
Re:Mineral? (Score:1, Informative)
Go explore the great wikipedia further and look up "homeostasis" and "buffering" (of the homeostatic type, you'll have to use a disambiguation link, I'm guessing... or start with a term like osmoregulation). Then look up "diffusion" and "active transport".
A few things about "mineral water": the reason you have to pee after you drink a lot of it is that the water diffuses into your body, triggering a homeostatic reaction that excretes the excess water. Water diffuses in living cells on this planet, and diffusion means it moves from a volume where the ion (salt) content is high through semipermeable membranes into volumes where the ion concentration is relatively low. There is no active transport of H2O molecules in terrestrial cellular life. Isotonic water -- which will taste quite salty to you -- will just stay in your intestines, rather than diffusing out of them. You may find yourself with very wet poo if you drink a lot of it, but otherwise it won't provoke urinary urgency or thirst. Hypertonic water -- really mineralized water -- will cause water to diffuse out of your body into your digestive tract, and you will feel thirsty.
The ions in solution in the water do not cross terrestrial life's semipermeable membranes by diffusion; they are actively transported. Mineralized water at most slows the passive diffusion of water by having a slightly lower osmotic difference between the mineral water and the rest of the body. The minerals would have to be actively transported out of the water.
Note that there are plenty of ions in whatever food you eat, and the concentration of them is much higher than in any water that you would be able to drink without gagging or vomiting. Active transport in your intestines moves them across the semipermeable membranes quite well.
Once the salts and other useful ions are moved into your circulatory system they are either concentrated into long term storage (mainly in bones) or float about in solution mediated by hormones that control thirst, urinary urgency, (probably but not definitively) salt cravings, and (more speculatively) pica.
Mineral water is usually 250-500 ppm (0.025%-0.05%) of dissolved ions. In vertebrates (including humans) the intracellular and extracellular fluids are usually carrying several percent (2-7%) dissolved solids.
From an osmosis perspective, the dissolved solids in mineral water, compared to tap water, is inconsequential. Bottled mineral water will still cause water toxicity taken in large quantities all at once, and the difference between death by bottled water and death by maximally pure distilled water will in a standard human amount to a couple of millilitres. Sports drinks are usually 6% sugar and ~0.5-2% dissolved ions and are isotonic, so you can drink an awful lot of it all at once without risk. (For a standard human, 10 litres of distilled, tap or bottled mineral water taken all at once will kill by water toxicity; sports drinks are more likely to kill by mechanical damage from forced expansion of the digestive tract, or by metabolic crisis from trying to process tens of thousands of kilocalories worth of sugars all at once -- maybe a hundred litres might do it, if you could figure out how to avoid massive explosive diarrhea and vomiting reflexes from defeating your attempt to find the upper limit.)
Finally, wrt water toxicity, the problem is mainly that the kidney can only filter out a few litres of urine an hour, and taking in water faster than that -- whether that water is in the form of wet food, or from the tap, or from alcoholic drinks, or from a water distillation apparatus --will overwhelm buffering responses by organs other than the kidney (osteoclasts, vacuole-stored ions), as well force its way through semipermeable membranes in the brain, causing tissue-damaging swelling. That cerebral oedema is the usual cause of death in water toxicity; it would be very strange if it was electrolyte imbalance involving other organs that did an otherwise hea
Re:We had pure water once... (Score:1, Informative)
> a tall, frosty mug of yeast piss infested water.... I mean beer...
There, fixed that for you