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Confirmed: Water Once Flowed On Mars
An anonymous reader writes "A new study based on observations last September by the Curiosity rover on Mars has confirmed that pebble-containing slabs of rock found on the Martian surface were part of an ancient streambed. The work provides some of the most definitive evidence yet that water once flowed on Mars. '[The pebbles'] smooth appearance is identical to gravels found in rivers on Earth. Rock fragments that bounce along the bottom of a stream of water will have their edges knocked off, and when these pebbles finally come to rest they will often align in a characteristic overlapping fashion. ...It is confirmation that water has played its part in sculpting not only this huge equatorial bowl but by implication many of the other landforms seen on the planet.' According to NASA, 'The stream carried the gravels at least a few miles, or kilometers, the researchers estimated. The atmosphere of modern Mars is too thin to make a sustained stream flow of water possible, though the planet holds large quantities of water ice. Several types of evidence have indicated that ancient Mars had diverse environments with liquid water. However, none but these rocks found by Curiosity could provide the type of stream flow information published this week. Curiosity's images of conglomerate rocks indicate that atmospheric conditions at Gale Crater once enabled the flow of liquid water on the Martian surface.'"
I realize I could easily look it up. But, what is the leading theory as to why the planet can no longer sustain liquid water. I know that in it's current condition with low gravity and lack of atmosphere it cannot sustain liquid water... But was Mars once larger?
Runaway atmosphere loss is a leading candidate due to a lack of a magnetic field (and those missing gigatons of rock)...
here is your answer.
Some people die at 25 and aren't buried until 75. -Benjamin Franklin
Perhaps I'm missing something, but the evidence cited in the article only seems to show that liquid of some kind once flowed on Mars. What further evidence do we have to think that it was water in particular?
The thick crustal material and low magnetic field have led to the loss of the atmosphere and lack of currently flowing water. Low magnetic field led to large impingement by solar wind and stripping of atmosphere. Low average density of planet let atmosphere escape. The thick crust has kept the mantle deep and there is no regeneration of gases and liquids from the interior. Low atmosphere, more radiational cooling and first water goes to ice and then CO2 goes to ice and reduces the atmosphere again. The Earth could have gone the same route, had an impact not spawned the moon and thined the planet of the lighter, thicker crustal material. Lots of imparted spin from the impact and a denser planet gets deep iron core spin to generate a protective magentic field. That field both protects the atmosphere and the biologicals from getting zapped. Would be fun to send lots of water and gas bearing comets to impact and terraform Mars, but it would all still leak out. So --- we are seeing prehistoric water, frozen in time,and relected by the rounded pebbles left behind in ancient Martian canals.
And it will again. I'm convinced that the sun has hot and cold cycles. As it warms up, the water on Earth will be vaporized and the ice on Mars will melt. Then it cools and reverses that. Nature's test then is can we develop far enough quickly enough to get to the other planet before it's too late. Of course, this is just idle conjecture. :)
There are few other candidate liquids. We know Mars has water ice. We've detected liquid methane elsewhere in the solar system, but Mars is too warm to support liquid methane. Liquid CO2 is unlikely because at Mars' current temperatures, you would need more than one Earth atmosphere of pressure to form a liquid, and a thicker atmosphere will usually mean a warmer planet.
The original liquid was of course heavy water which (as every schoolboy knows) breaks down over time to become ordinary light water. This then floated off into space.
There is no such thing as liquid CO2. Only artificially high pressures can prevent it from sublimating, and as I'm sure you realize, a planet that can't even retain its atmosphere is unlikely to have somehow maintained an atmospheric pressure 5 times that of the Earth in the past.
Water is an extremely common and simple substance that you can find all over the universe.
So according to Occam's razor... what else could it possibly have been?
There is no "final confirmation" in science
I can confirm. This is true.
Sorry, couldn't resist!
"For every expert, there is an equal and opposite expert"