Starship Asterisk*

Chris Peterson wrote: ↑Mon Apr 22, 2019 1:31 pm

BDanielMayfield wrote: ↑Mon Apr 22, 2019 1:27 pm My hunch is that sporadic methane on Mars is from a non biological source.

Probably true. But still an intriguing mystery.

The two main routes for geological methane generation are (i) organic (thermally generated, or thermogenic) and (ii) inorganic (abiotic)[28]. ... The more important source of methane at depth (crystalline bedrock) is abiotic. Abiotic means that the methane formation took place involving inorganic compounds, without biological activity, either through magmatic processes or via water-rock reactions that occur at low temperatures and pressures, like serpentinization.[29][30]

Serpentinite is a rock composed of one or more serpentine group minerals, the name originating from the similarity of the texture of the rock to that of the skin of a snake.[1] Minerals in this group, which are rich in magnesium and water, light to dark green, greasy looking and slippery feeling, are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle. The mineral alteration is particularly important at the sea floor at tectonic plate boundaries.[2]
...
Serpentinization is a geological low-temperature metamorphic process involving heat and water in which low-silica mafic and ultramafic rocks are oxidized (anaerobic oxidation of Fe2+ by the protons of water leading to the formation of H2) and hydrolyzed with water into serpentinite. Peridotite, including dunite, at and near the seafloor and in mountain belts is converted to serpentine, brucite, magnetite, and other minerals — some rare, such as awaruite (Ni3Fe), and even native iron. In the process large amounts of water are absorbed into the rock increasing the volume, reducing the density and destroying the structure.[3]

The density changes from 3.3 to 2.7 g/cm3 with a concurrent volume increase on the order of 30-40%. The reaction is highly exothermic and rock temperatures can be raised by about 260 °C (500 °F),[3] providing an energy source for formation of non-volcanic hydrothermal vents. The magnetite-forming chemical reactions produce hydrogen gas under anaerobic conditions prevailing deep in the mantle, far from the Earth's atmosphere. Carbonates and sulfates are subsequently reduced by hydrogen and form methane and hydrogen sulfide. The hydrogen, methane, and hydrogen sulfide provide energy sources for deep sea chemotroph microorganisms.[3]
...
Abiotic methane production on Mars by serpentinization

The presence of traces of methane in the atmosphere of Mars has been hypothesized to be a possible evidence for life on Mars if methane was produced by bacterial activity. Serpentinization has been proposed as an alternative non-biological source for the observed methane traces.[7][8]

Ann wrote: ↑Mon Apr 22, 2019 1:35 pm Do I take it that methane has only ever been detected in (or over) certain locations on Mars? So that the idea of colorizing the parts of Mars where methane has never been detected seems stupid?

Chris Peterson wrote: ↑Mon Apr 22, 2019 1:09 pm

orin stepanek wrote: ↑Mon Apr 22, 2019 11:15 am .
Maybe the Methane on Mars is seasonal???????????????

Every indication suggests that it is. The mystery is related to the problem that even within that understanding, the detection results are not consistent.

https://en.wikipedia.org/wiki/Martian_canal wrote:

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<<Astronomers saw some lighter or darker albedo features (for instance Syrtis Major) and believed that they were seeing oceans and continents. They also believed that Mars had a relatively substantial atmosphere. They knew that the rotation period of Mars (the length of its day) was almost the same as Earth's, and they knew that Mars' axial tilt was also almost the same as Earth's, which meant it had seasons in the astronomical and meteorological sense. They could also see Mars' polar ice caps shrinking and growing with these changing seasons. It was only when they interpreted changes in surface features as being due to the seasonal growth of plants that life was hypothesized by them.

During the [Mars] oppositions of 1892 and 1894, seasonal color changes were reported. The idea that Schiaparelli's canali were really irrigation canals made by intelligent beings was first hinted at, and then adopted as the only intelligible explanation, by American astronomer Percival Lowell and a few others. The visible seasonal melting of Mars polar icecaps fueled speculation that an advanced alien race indigenous to Mars built canals to transport the water to drier equatorial regions. Newspaper and magazine articles about Martian canals and "Martians" captured the public imagination. Lowell published his views in three books: Mars (1895), Mars and Its Canals (1906), and Mars As the Abode of Life (1908). He remained a strong proponent for the rest of his life of the idea that the canals were built for irrigation by an intelligent civilization, going much further than Schiaparelli, who for his part considered much of the detail on Lowell's drawings to be imaginary. Some observers drew maps in which dozens if not hundreds of canals were shown with an elaborate nomenclature for all of them. Some observers saw a phenomenon they called "gemination", or doubling – two parallel canals. The late 19th century was a time of construction of giant infrastructure projects of all kinds, and particularly canal building. For instance, the Suez Canal was completed in 1869, and the abortive French attempt to build the Panama Canal began in 1880. It is understandable that 19th century people who accepted the idea of a Mars inhabited by a civilization might interpret the canal features as giant engineering works.

Chris Peterson wrote: ↑Mon Apr 22, 2019 1:07 pm

Ann wrote: ↑Mon Apr 22, 2019 4:59 am I find the video confusing. Why is some of it in color and some of it in black and white?

None of it is in black and white. If that's what your monitor is showing, it needs to be calibrated or replaced.

Yes, I realize that the colorized part of the video doesn't represent real color, just a measure of methane concentration. But why the dichotomy of one colorized hemisphere of Mars and one black and white one? If Mars now lacks methane, wouldn't it have been better to produce two side-by-side colorized hemispheres of Mars, where one hemisphere was "all blue" and lacked the red signal of high methane concentration?

The visualization was made by using a photographic map of Mars, overlaying it with methane data where data are available, and then mapping it onto a sphere and animating the rotation. There are, of course, static maps of the same data. The intent here was to add the rotation.

BDanielMayfield wrote: ↑Mon Apr 22, 2019 1:27 pm My hunch is that sporadic methane on Mars is from a non biological source.

orin stepanek wrote: ↑Mon Apr 22, 2019 11:15 am Maybe the Methane on Mars is seasonal??????????????? :roll: :shock: :?

Ann wrote: ↑Mon Apr 22, 2019 4:59 am I find the video confusing. Why is some of it in color and some of it in black and white?

Yes, I realize that the colorized part of the video doesn't represent real color, just a measure of methane concentration. But why the dichotomy of one colorized hemisphere of Mars and one black and white one? If Mars now lacks methane, wouldn't it have been better to produce two side-by-side colorized hemispheres of Mars, where one hemisphere was "all blue" and lacked the red signal of high methane concentration?

JohnD wrote: ↑Mon Apr 22, 2019 9:28 am
I'd criticise the video for showing nothing about the geography under the colour contours. What structres are assocaiated with the methan plumes?

John