2/11/2003: Gullies on Mars

It may take a while to load, but the detail on this one is important. This is an Astronomy Pic of the Day pic showing some of the surface of Mars from orbit.

Why this is cool: it sure looks like those formations came from water, doesn't it? And on Earth, similar formations are generally caused by water. So they feel these images are further evidence of underground water on Mars. Not at all far underground, either; 30-60 centimeters.

Note that the above image is 1500 meters across.

The key is to find out when these gulllies were formed. If you look closely, you can see what appears to be a half-buried runway. I'd look at it and say, "Hey! That natural feature looks like a runway; how odd." A conspiracy theorist would start screeching and braining peccaries with a wildebeast femur...

i see it too

I see the runway. And I see Jesus with a mustasche in the lower right corner. This is solid evidence that Christians were baptised in the waters on Mars....

I was kinda entranced by the flaccid penis and scrotal sac at the top center of the pic ... MUCH more convincing than the "face on mars" pic that is in the tabloids all the time.

Wolf, if no one has mentioned that you are amazingly astute and more than slightly warped, then it was a major oversight.

Did you end up in the mental health industry *because* of these factors or *despite* them?

All of your discoveries pale in comparison to mine: there is a rake on Mars.

No longer will our young be conscripted into slave labor come Autumn! We will conquer and enslave Martians with pride and honor, like our forefathers before us!

That's no rake. It's a kitty litter scoop.

And the rivulets and gullies? From cat pee!

This is the terrible secret of space! Where is the pusher robot?

Quote:

Originally posted by Elspode Wolf, if no one has mentioned that you are amazingly astute and more than slightly warped, then it was a major oversight. Did you end up in the mental health industry *because* of these factors or *despite* them?

There are some hikers out in the woods on the lower left. Above them seem to be two nude women. A big, downtrodden person is dragging their arm behind them on the right.

Okay, seriously, folks.

The escarpment on the left, with the rivulents leading away from it looks like a lot of the features in the 'basin and range' area of Colorado, Nevada and Utah. When I drive from Vegas to the Grand Canyon area, a lot of the geography inbetween looks like this.

The rising up of that escarpment, and its erosion by liquid, presumably water, must have happened fairly recently, or it would have been destroyed by meteor strikes, c.f. the earth's moon. What 'recently' means, I don't know. A million years? A hundred million? Definitely less than a billion, I'd guess, but I don't know enough of exogeology to be sure.

They could be quite old indeed, mars is slowly losing it's atnosphere so the further you look back the less the chance of meteor damage, actual scales of time on this though? I have no idea.

They can't fool me, that's just a picture of some kids sandbox. Don't forget when they said they landed on the moon, it was all filmed on a sound stage near Vegas. I saw that James Bond film!

The Serious Reply

I've been spending a lot of time looking at the gullies image, including the larger resolution version available on the originating website.

The "gullies" are certainly suggestive of a formation type known to be caused by water erosion on Earth. There, however, is the operative statement. On Earth. I don't know that we have enough information regarding the composition of Martian soils to accurately predict the behavior under the particular conditions of temperature, wind, and gravity.

We need more information about the wind speed characteristics, the composition and hardness of the underlying rock, and the hardness of the soil particles that would be scouring that surface under a high wind ... which is another thing. I don't see anything that really stands out as wind erosion. Those features may not have changed over centuries or longer.

There are a couple spots near the bottom center of the picture that do look like the coronas that form from a meteor strike. Those are not disturbed much, so I'm guessing that it's not a windy area.

There ARE features which appear to be slips or subseidance of some kind ... particularly at the bottom of that big "hill" to the middle right.

Theory

i'm going to throw out a theory here. i might be missing something.

Could a small comet have hit the area, at a semi-shallow angle, scattering debris including ice/slush to the top left of the picture. The new dust ejected from the impact would not be very hard packed, so it wouldn't take a lot of water from the comet to make the gullies. The water then simply soaked into the ground. The apparent water could be an anomaly rather than evidence of widespread water on Mars.

Thank you, that is all.

"Hey, what is this, some kind of tube?" -Bill Clinton

Rivulets

I remember reading a possible explanation of 'water erosion' features when the first evidence of them popped up. Turns out that as frozen CO2 sublimates on a slope, bits can break off and, contacting the warmer ground below, form a cushion of gaseous CO2 that facilitates the slide further down the slope, contacting yet more warm ground etc (by warm I mean hotter than the sublimation point of CO2, around -78deg C).
So it could have been chunks of solid cascading down the slope, buoyed by cushions of gas, which in the aggregatel can be a reasonably 'liquid' phenomenon.
The problem with liquid water flows on the surface any time in the (geologically) recent past is the temperature and pressure measurements we have seem to make it very unlikely. Still its a long ways away and there is much more to learn about this remote, forbidding planet

I to have found a picture proving life on Mars.

This I believe to be the first sighting of a mouse on mars.

I suddenly have to have some chocolate ice-cream.

Maybe it was a, what's the word, um... a big (yeah, that's the word) comet that was smashed into little bitty pieces before it landed, kinda like the fireworks on Jupiter not so long ago. Perhaps the happinings are all along a straight line, or perhaps the comet landed in a scatter pattern rather than single file like Shoemaker-Levy 9. Just hypothanesthetising.

"Would you like to swing on a star, or would you rather be a pig?"

The most likely explanation

In brief: snow forms in these craters in the winter months, then later melts - from the rim of the crater down - and the water flows under the still frozen snow further down the slope, which protects it from evaporation in the tenuous atmosphere. If it were a subterranian (subarean?) water source, its unlikely to occur so close to the raised crater rims. This explanation is the most consistet yet.
http://science.nasa.gov/headlines/y2...htm?list922696