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Mars Rover Sniffs First Hint of Water?
mhw25 writes "It is reported that the Mars rover Spirit is already well into its scientific mission, and may be detecting hints of water. The mini-Thermal Emission Spectrometer has returned its first image, with probable evidence of carbonates and hydrated minerals. We may know more after the rover rolls off its landing base, after making a 120 degree turn to avoid the airbag blocking its front ramp, to start analyses on soil from Thursday or Friday. An ongoing intrigue is already developing - a scientist reckoned that some of the soil around the airbag 'looks like mud, but it can't be mud'."
It can't be mud because of physics. Water cannot exist in free form in the surface of Mars because it would simply evaporate instantly (at least in most locations). Temperature and atmospheric pressure are the usual suspects here. And we do know what those are with a relatively high degree of certainty. Ergo, it can't be mud. It must be some sort of wacky sand, like montmorillonite. Data from the Mariner probes has detected a few dozen types of this clay. Maybe this is one we haven't seen before.
Water, if found, will be either in the poles or trapped in molecule-sized amounts in rocks under the surface, nominally because of some sort of organism like microscopic algae or fungus keeps it there as part of its organic cycle. The idea goes that if you find water there you're also likely to find some type of primitive life.
But I suggest we let the thing dig holes and stuff before we get all excited =)
Last I heard they'd found bound water, and the surface was a lot hotter than they expected it to be. In the last image release I notice they show a graph of the temperature (presumably up near the Pancam) at ~1m above the surface - the great thing about Mars' atmosphere is how quickly it get's cold the higher you get - i.e. very. Like, your feet could be warm and your head would be a solid block of ice.
:)
The kinda cool thing is the TES data shows a current temperature map at surface level - you notice at Gusev Crater (where spirit is, about 15S, 185W - so basically around halfway down the right edge of the picture) the temperature is somewhere around 0C, +/-10 degrees or so.
The *really* cool thing is, when they were getting ready to make the rover stand up and strut its stuff, they went through extra checks and testing on Earth because the landing site was a lot warmer than they expected - there's every chance that it's above 0 there, in fact, there's every chance that (on the surface at least) Spirit is enjoying much better weather than I am right now.
It's common knowledge that Mars' equator regularly gets up into the positive numbers, even up above 20c, the only real question as to the feasibility of liquid water in these regions is whether there is any ice left there to melt, or if it is all up at the poles (or underground). Due to the low triple point of water on Mars, and the theory that it's just coming out of an ice-age, there's every chance there is no liquid left around there to melt, but there's certainly a chance there is.
Fortunately, we have a rover up there that will be able to tell us for sure in a few days
That's misinformed, that's the temperature ~1m above the surface, the surface temperature does indeed rise above zero, and I believe has been since before Spirit landed
Real surface temp graph
Great point: but the surface of Mars isn't just fine dry powders; it's fine dry powders in relatively low gravity. The behaviour of this isn't something we're familiar with and it may be that which is spooking the unnamed scientist.
Is the reason it "can't be mud" that it would have shown up as such in previous spectroscopic analyses from orbit?
Utter rubbish. Water doesn't dissociate into hydrogrn and oxygen just by being boiled. The interatomic forces holding the molecule together are not broken. You can make it dissociate by electrolysis but it does not happen through boiling. If it did it would be quite inadvisable to light a match anywhere near a kettle, given that a mixture of hydrogen and oxygen is just a bit flammable!
Each water molecule is polarised (quite strongly as it happens): although it is overall electrically neutral, one end is rather positive and the other end is rather negative. You get residual interactions between the positive end of one molecule and the negative end of the next one along. When the water molecules are extremely cold they are held in a lattice structure by these residual dipole moments. This is ice. When you add some heat the water molecules jiggle around, and eventually have enough energy to break the lattice and move around freely, though they are still attracted to each other because of the electrical dipoles. This is water. Add some more heat energy and the jiggling water molecules move so fast that they have enough kinetic energy to break out of the energy well of the intermolecular bonds. They can move around at will and each molecule can go where it wants. This is water vapour. The temperature at which these changes occur depends on pressure for reasons that you can go and look up.
What you see as steam when a kettle boils is actually liquid water that cools and recondenses into countless tiny droplets above the kettle's spout.
"'I pass the test,' she said. 'I will diminish, and go into the West, and remain Galadriel.'"
- JRR Tolkien.
Anyway, the quote was elicited only when one of the reporters there asked "to me it looks like mud, any chance it could be". The reply was that although it might look like mud, it couldn't be, followed by a description of the behavior of fine particles (they can flow, etc.).
I'd say that to use this as a quote that "scientists say" it looks like mud is a bit disingenuous.
Opinions my own, statements of fact may contain errors