So the news has been posted that NASA thinks there is flowing water on Mars. I read several of the reports - they are apparently all coming from one statement made by Nasa that there is salty water flowing, during the summer months (-10 degrees or above).
The salts in the water allow it to flow, and the flow may be through the upper soil rather than on top of the soil.
How likely is this? I know Nasa has been watching the planet, but is this more ‘it could be’ speculation or ‘very probably true’? If true, wouldn’t this make visiting Mars/life on Mars more feasible? Because, source of water, even if it needs filters to be drinkable.
The evidence is only indirect, but it’s pretty good evidence. However, the question of where the water could be coming from is a big one, so I’m not sure we could say “very probably true” until there are some logical explanations.
To add my question: coverage of this often mentions the streaks are observed in months when the temperature rises to -23 C (-10 F). But water saturated with NaCl freezes at -21 C. Are the reports of temperatures wrong, or are there other salts/substances hypothesized to be in the water that would further lower the freezing point?
Lujendra Ojha, Mary Beth Wilhelm, Scott L. Murchie, Alfred S. McEwen, James J. Wray, Jennifer Hanley, Marion Massé & Matt Chojnacki
Nature Geoscience (2015) doi:10.1038/ngeo2546
Received 22 April 2015 Accepted 21 August 2015 Published online 28 September 2015
Determining whether liquid water exists on the Martian surface is central to understanding the hydrologic cycle and potential for extant life on Mars. Recurring slope lineae, narrow streaks of low reflectance compared to the surrounding terrain, appear and grow incrementally in the downslope direction during warm seasons when temperatures reach about 250–300 K, a pattern consistent with the transient flow of a volatile species1, 2, 3. Brine flows (or seeps) have been proposed to explain the formation of recurring slope lineae1, 2, 3, yet no direct evidence for either liquid water or hydrated salts has been found4. Here we analyse spectral data from the Compact Reconnaissance Imaging Spectrometer for Mars instrument onboard the Mars Reconnaissance Orbiter from four different locations where recurring slope lineae are present. We find evidence for hydrated salts at all four locations in the seasons when recurring slope lineae are most extensive, which suggests that the source of hydration is recurring slope lineae activity. The hydrated salts most consistent with the spectral absorption features we detect are magnesium perchlorate, magnesium chlorate and sodium perchlorate. Our findings strongly support the hypothesis that recurring slope lineae form as a result of contemporary water activity on Mars. (Graphs and photos available at cite.)
As I understand it, the evidence goes roughly thusly:
Dark streaks have been seen that exist only in warm weather, and which seem to flow in patterns like you’d expect actual fluids to flow. Spectroscopic analysis (basically, looking really really REALLY closely at what color the streaks are) shows patterns that are the fingerprints of certain salts and chemicals that can only exist in liquid water.
Like many people I’m pretty excited to hear about flowing seasonal water on Mars. My co-worker is bored, she reminds us that they found bacterial fossils from Mars. I’m not as convinced about that – that was a long time ago, but it didn’t seem definitive at the time, and time hasn’t strengthened the topic. Wikipedia just gives the facts, but does the scientific community still hold these microfossils from a Martian-derived meteorite as valid? As I recall, at the time, these bacterial fossils were smaller than terrestrial bacteria – not what I personally picture as a survival adaptation for a meager environment such as Mars. And it was possible that these were a certain type of mineral masquerading as fossils. Any latest opinions?
Depends on what you mean by “valid”. Those rocks are definitely from Mars, and they definitely have little spherical structures in them. Just what those spherical structures are is a matter for some debate. Even if they might actually be fossils, well, that’s a pretty extraordinary claim, and the evidence isn’t extraordinary enough.