13

tl;dr: Compared to Earth, the atmosphere on Mars is very thin; in addition, it contains much less of oxygen and water (i.e., is very dry). It is much colder there. These conditions may slow down oxidation to an irrelevant rate. For an object of pure iron, note that according to the English Wikipedia about Mars: "The atmosphere of Mars consists of about ...


11

You are looking for a portable XRF. It does (almost) exactly what you said. It sends electromagnetic radiation to the rock (X-rays), which excites electrons in the atoms and when they bounce back they return X-ray of different energies which are detected by the instrument. It looks like this, for example: Using the different peaks you can figure out what ...


7

$\rm \frac{mol}{m^2}$ shows the amount of $\rm{NO_2}$ in the atmosphere over a square meter of surface area - in mols. The molar mass of the $\rm{NO_2}$ is $14+2\cdot 16=46$. It means, the mass of 1 mol of $\rm{NO_2}$ is $\rm{46g}$. The surface area of the Earth is 510million $\rm{km^2}$. Thus, 1 $\rm \frac{mol}{m^2} \rm{NO_2}$ translates to $\rm{46 \frac{...


6

First, note that this plot is normalized to a reference, here the composition of CI chondrites (your version lacks the Y axis label, it's figure 2.1 from Walker 2016). So if the concentration of highly siderophile elements (HSE) seems uniform, it's partly because it is a relative concentration, not an absolute one. If you look at the raw data (Table 1.1), ...


5

From the comments: And indeed, after browsing trough a few sections they seem to assume that "Liquid metal separates rapidly from liquid silicate", like oil and water, and they don't mix later. Very interesting. I wonder what's @Gimelist opinion about this. You are very correct. The answer is simple: the core and mantle are immiscible. The core ...


4

This is because of historical inertia. Yes, you are correct that "mass" is technically more correct than "weight". However, because these are percentages, it does not matter. There are no units. A rock that has 50 weight% SiO2 also has 50 mass% SiO2, regardless of the planet (i.e. g) you are in. Regarding using "ma%" - I have never seen it and it would be ...


4

Increasing CO2 concentration in the atmosphere is leading to an increasing concentration of dissolved CO2 in sea-water. The dissolved CO2 then reacts with the water to create carbonic acid, decreasing the pH as recognised in the question. The solubility of CO2 in water does decrease with increasing temperatures, so the maximum amount of CO2 that can be ...


3

Sea water is all very corrosive; the precise composition is not significant. Steel structures are cathodically protected with impressed current and/or sacrificial anodes, usually aluminum. For equipment to be cooled with seawater there are a few choices ;However, for the Navy where reliability is more important than the cost , titanium would be the material ...


3

To piggyback on Gimelist's answer: Another important tool X-ray diffraction. XRD is used to determine crystalline structures. Specifically, XRD sees the dimensions of different crystals (and most "rocks" are crystalline). When used with the information that XRF or other elemental analyses produce, skilled operators can identify what specific materials are ...


3

My speculation is that if you try to use ma% or mas%, you will be asked to change it to wt%, because what you are proposing is not yet standard usage. If I came across ma%, my initial though would be "what does that mean". My second thought would be, "does it mean milli annums percent?", (thousandsths of a year percent) - which would be meaningless to me. ...


2

What you can see in the bottom picture is sandstone/mudstone/claystone. If you look at the bottom picture top right you can see a thin rock that has split off, this is how a rock splits after it has been heated and then suddenly gets cooled down as it does on Mars when the Sun goes down. On Earth the change in temperature is too slow for this to happen in ...


2

Conventions, whether set by standards or by common usage, are not always in line with the most intuitive or the "most accurate" approach. Would for example that the electrical engineers would stop writing that current flow is in the direction of motion of positive charges rather than that of electrons, we will all be "more accurate". As has been noted, the ...


2

I've found two sources for molecular hydrogen. The photolysis of formaldehyde (See chemical formula 10 and see Novelli et al. 1999) Anthropogenic sources. While it isn't a source I think I should mention the exosphere. The exosphere is not very dense, so hydrogen (probably) doesn't react with anything. Since it is the lightest element, it probably doesn't ...


2

Besides man-made sources, hydrogen can be produced naturally through a process called serpentization. Mafic and ultramafic rocks, which are rich in magnesium and iron silicates, react with water to produce a variety of breakdown products summarized in the Wikipedia article on serpentine Serpentinization is a geological low-temperature metamorphic process ...


2

Another good historical perspective from this blog: http://lablemminglounge.blogspot.com/2006/09/iridium-anomaly-as-historical-artifact.html Iridium anomaly as historical artifact Everybody knows that way back in 1980, Alvarez et al. showed that Italian sediments deposited on the Cretaceous / Tertiary boundary (and NOT the Cretaceous / Paleogene boundary, I ...


2

I didn't really understand where did this "one-sixth of the escape velocity" figure come up from. The "one-sixth of the escape velocity" a ballpark number. As a general rule, three sigma events (events that are three standard deviations from the mean) happen all the time, while twelve sigma events are so very, very rare that they can ...


1

The pH of ocean water is currently about 8.1, which lies between the second and third dissociation constants (7.20 and 12.37, respectively). So most of the phosphate inthe ocean in its twice-dissociared form, as $\text {HPO}_4^{2-}$. For comparison, our own blood is around pH 7.4, so phosphate in our blood would be a mixture of $\text {HPO}_4^{2-}$ and $\...


1

The average concentration of gold in Earth's crust is about 2 ppb (±0.5, depending who you're asking). This is about 2 milligrams Au per tonne of rock. It's not much, but it still equals about 6×1018 atoms, or 6 billion billion atoms. Seawater has on average 0.004 ppb of gold. This equals 4 micrograms Au per tonne of seawater. Much less, but still about 1×...


1

"The decrease in δ13C as water flows from the Atlantic to the North Pacific is due mainly to the addition of organically produced material and its subsequent oxidation as it falls through the water column. Marine organic carbon has a δ13C of near -250/00, hence the addition of this material decreases the δ13C of the ΣCO2." (from ...


1

If you enlarge the picture and follow a line at 1 o'clock from the weirdly shaped piece in question, a few feet away from it at the back of an imaginary 'man's head' rock, you will see a similar convoluted piece. Now follow a line at 10 o'clock from our original specimen, and also a few feet away is a longer,straighter piece in the process of eroding from ...


1

A solid to solid transition can occur between two enantiotropically related polymorphs without going through a melt. Whereas for monotropes conversion can only take place once the material has melted. In other words the transition temperature between enantiotropically related polymorphs is below the melt of the lower temperature melting polymorph whereas ...


1

The first department that comes to mind is obviously academia, i.e. faculty or research positions at universities. However, there are many other career paths available (hopefully: there are not enough academic positions for every student completing a Ph.D...). For volcanologists, there is actually a nice site called volcanologists outside academia. As the ...


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