Water Ice On Mars

cathector sends along a story from SpaceWeather.com on the discovery of water ice on Mars. "Scientists have figured out the mysterious white substance unearthed by NASA's Phoenix lander on Mars. It's frozen water. The breakthrough came last week when Phoenix's stereo camera caught the substance in the act of disappearing. Bathed in martian sunlight for four days, the white substance sublimated — i.e., it transformed from solid to gas without passing through the liquid state. This is how water behaves on Mars.... Some readers have asked, how do we know the white substance is not frozen CO2 (dry ice) instead of frozen water? Answer: Phoenix's landing site is too warm for dry ice. The average daily temperature is about -70 F while dry ice requires temperatures lower than about -109 F." The animated GIF showing the ice sublimating is pretty nice too.

Comments

Interesting press coverage of this.

[Gavin Scott]

I've noticed that almost all of the news headlines covering this are qualified statements like "Lander finds water on Mars, according to scientists". As if they're afraid to actually say something straightforward like "Water found on Mars" and they have to make it clear that they're just reporting what someone else is saying (with the implication that maybe they don't really believe it). At the same time they seem to have no problem with other headlines like "Celebrity Arrested Drunk" without the need to qualify it as "Celebrity Arrested Drunk According To Police" etc.

Maybe it's just me, but I mind it a bit irksome that so many big news outlets seem so detached from any sort of science reporting these days.

G.

average daily temperature

[Swampash]

Could we have this important information in units used by, I don't know, the rest of the world?

ice on Mars is nothing new

[speedtux]

Finding water was one of the key goals of the Phoenix mission.

That is a bizarre statement. Large quantities of ice have been observed in numerous ways already. Even the Viking lander observed water frost directly in the 1970's:

http://en.wikipedia.org/wiki/Viking_2

http://www.solarviews.com/cap/mars/frost.htm

That frost sublimated just like this ice did.

Here are other observations:

http://science.nasa.gov/headlines/y2002/28may_marsice.htm

Here you can see a frozen crater lake:

http://esamultimedia.esa.int/images/marsexpress/210-010705-1343-6-co-01-CraterIce_H.jpg

http://www.esa.int/SPECIALS/Mars_Express/SEMGKA808BE_0.html

Not only is that ice, it may actually be an outflow.

What makes the results from Phoenix exciting is that the actual experiments that Phoenix is supposed to perform depend on having landed on ice. But finding ice somewhere on Mars is not a surprise.

Re:Water sublimating

[PieSquared]

Pretty much anything can sublimate under the proper conditions. But when you say "a white solid that sublimates at -70 degrees F and martian surface pressure and is found in macroscopic quantities naturally" you narrow down the field quite a bit. In this case, to exactly one reasonable possibility.

Re:Wind?

[Jafafa Hots]

OK, we admit it - none of the NASA scientists are as smart as you are, the whole "powder" thing just never occurred to them. Doh!

Re:Wind?

[Free the Cowards]

Neither, because NASA only hires smart people.

Re:Wow - not

[ThePeices]

There is a fair bit of difference between believing and knowing!