Slashdot Mirror
Brine on Mars?
Bagels writes "A new article on MSNBC (coming originally from Space.com) reports that the both Rovers may have struck water in the form of brine. The Opportunity rover found hints of salty water in the trench that it dug, and scientists note that the Spirit rover is currently digging a trench of its own to investigate the soil that clings to its treads, suggesting the possibility of moisture. The brine would only be small amounts of water mixed with salt, which can exist in liquid form at very low temperatures. More images are available over at NASA's rover site." Reader
frovingslosh would like to add: "I'm just hoping that when you get around to posting one of the many stories that the rover has found mud on Mars that you might include a link to the slashdot article where I predicted this but got moderated as 'funny'." Done!
I'd be interested to see what kind of hardware/bandwidth NASA have cos they serve up images and movies 24/7 and never seem to get slahdotted...
..why did it not evaporate?
The atmospheric pressure on mars is pretty low, which means that any liquid water (which this apparently is) will be vacuum dried to gas and move into outer space.
If an experiment works, something has gone wrong.
The very small particle size of Martian dust makes it likely that it sticks due to static charge. If the soil were moisture laden you would expect it to rapidly dry out and crust over (change appearance) on the wheels of the rover.
an ill wind that blows no good
This raises the possiblities of halophiles living on Mars. On Earth, halophiles can live in up to 35% salt solutions. Pure water would kill these creatures --causing them to aborb water until they burst.
Its no wonder that Viking found no clear evidence of life on Mars, the low-salt water in Viking's nutirent broth probably killed any halophiles.
Two wrongs don't make a right, but three lefts do.
I think they should take a picture at night so we can see what Mars' moons look like.
Rather than having the rovers scratch the surface or look at billion year old craters what they should do is send a large lump of heavy metal (say, 500 lbs) to Mars and, with it protected by a heat shield, slam it into the surface like an meteorite. Not having to account for parachute wind drift they could be pretty accurate with such a targeted blow and the result would be a small -fresh- crater. The crater could be observed by sensors in orbit and a rover landed in the vicinity shortly thereafter. Both the man-made meteorite and the rover could be sent together and initially orbited so as to allow time for a precise hit and accurate rover reentry.
======= ~\_/~\_O Burmese
Deimos and Phobos, while closer (23459 and 9378 km) to Mars than Luna is to Earth (about 384400 km), also have much smaller masses (1.8e15 and1.08e16 kg) than Luna (7.35e22 kg). [source]
Tidal forces (being a function of gravitational differential) are an inverse-cube function on distance, and linear with mass, so that would be a tidal force about 1/99th that of which we're used to. (Disclaimer: I am not a Physicist, but I share a house with one.)
While this is Mars, the concern isn't completely insane. If the rover's in position to get a 1% response from the Martian equivalent of the Bay of Fundy, we'll be needing yet another Mars probe, and someone at NASA should be needing a new job for putting it there.
//Information does not want to be free; it wants to breed.
I keep seeing references in the rover news about the microscopic imager, but is this really a microscope, or is it just magnifying as much as say a desktop macroscope for opaque objects (they let you see things around the size of a hair okay..? If there were things the size of microorganisms in the briny reaches, could we see them? It is impossible for the layman to look at the closeups we've been seeing and understand how big the field is.
Gases do move into outer space. Gravity slows down the process, but it doesn't stop it. When you get to the outer atmosphere, the velocity of gas atoms and molecules follow a predictable statistical distribution, dependent on their atomic mass and average temperature. Many atoms and molecules will reach escape velocity, and diffuse away from the planet. What do you think happened to the atmospheric helium on Earth?
Molecular weight of helium: 4
Molecular weight of water: 18
Gases escape over geologic time if the mean particle velocity is more than about a tenth escape velocity (if I recall correctly). Light particles at a given temperature (defined by average particle kinetic energy) move faster and so are lost more readily. Heavier particles are moving more slowly, and so are lost at a _much_ slower rate (the tail of the Boltzman distribution is exponential).
The real reason Mars has relatively little water is that water is broken up in the upper atmosphere by interaction with solar UV. While water may not be light enough to escape, hydrogen definitely is (molecular weight 2, and weight of an atomic hydrogen radical formed by a UV event is 1). This mechanism works on all of the planets (especially the inner ones) to strip their atmospheres of hydrogen.
Mars has a less active geology than Earth. We get hydrogen compounds (including water) replenished from volcanic sources. Earth also has a much higher escape velocity, which means that hydrogen is lost less quickly when formed (and has longer to recombine to form chemicals with higher molecular weight).
Both of these help explain why Earth is wet and Mars isn't. On the short term, however, water stays bound in Mars's atmosphere just fine. Those ice caps that migrate seasonally via atmospheric gas transport aren't all CO2, you know.
You can find a number of documents online discussing why Venus did get stripped of most of its water, despite being heavy and having a fairly active geology.