



I. Take me to the River






II. An Odd Location



Aeolis Mons




III.  Rover Prepares to Dig for Water, Organics








IV. A Third Generation Design




NASA rovers



Source: JPL

Comments     Threshold


Maybe it isn't water.
By drycrust3 on 9/30/2012 3:19:16 PM , Rating: 2

I've been thinking about this, and it seems to me that almost any reasonable fluid that could exist in the Martian climate could have produced this result. Since there is no obvious dating mechanism bar the amount of dust on surface, this stream bed could have just as easily be made 10 years ago as 10,000 years ago. Looking at the thin layer of dust on the pebbles, I would suspect a more recent date than a older date.
According to Wikipedia, the Martian atmosphere has a mean surface pressure about 0.6% that of earth at sea level, and the temperatures are around 210 Kelvin. The Wikipedia entry on Martian climate suggests a mean temperature of -55C, i.e. 218K.
Because of the thin atmosphere, it may be that even if the Martian temperature did, on the rare occasion, get above 273K - 0C, water may not actually exist as a liquid on Mars because it would immediately boil off and become a gas.
Carbon dioxide is the main constituent of the Martian atmosphere. It has a melting point of 194K (-78C, -109F), and, using an atmospheric pressure of 5.185 bars (5 times earth's air pressure), has a boiling point of 216K (-57C, -70F), meaning the window of opportunity for liquid CO2 to exist on its own on Mars is almost non-existent.
Looking at the melting and boiling points of some of other the different Martian gases, it seems to me another remotely possible contender is Formaldehyde (CH2O), which is present in minute amounts in the atmosphere, but has a melting point of 181K (-92C, -134F) and a boiling point (at 100KPa - earth sea level pressure) of 254K (-19C, -2F).
Thus, it may be that either early in its life Mars did, for a short while, have a climate that included liquid water; or that some sort of combination of chemicals e.g. a carbon dioxide - formaldehyde mix, forms as a liquid on rare occasions in sufficient quantities so as to create streams.

