This was published recently on ScienceAlert.  Found the link on the Fediverse.  I am posting here under geology as I seems more appropriate

https://www.sciencealert.com/in-an-incredible-first-scientists-have-discovered-whats-at-the-core-of-mars

So posting as it may be of interest to geologists as

 

One question if elements such as Sulfur have formed would that perhaps suggest that elements such as Nitrogen may also be or may have formed at some point ?

2 hours ago, paulsutton said:

This was published recently on ScienceAlert.  Found the link on the Fediverse.  I am posting here under geology as I seems more appropriate

https://www.sciencealert.com/in-an-incredible-first-scientists-have-discovered-whats-at-the-core-of-mars

So posting as it may be of interest to geologists as

 

One question if elements such as Sulfur have formed would that perhaps suggest that elements such as Nitrogen may also be or may have formed at some point ?

Interesting article. Thanks for posting it.

One would not expect nitrogen-containing compounds among the minerals. About the only example on Earth is saltpetre (KNO3 or NaNO3), which is derived from decomposition of organic material. This is because nitrogen is generally speaking most stable as N2, a gas, due to the great strength of the triple bond (excellent overlap of the 2p orbitals in this small molecule, leading to 2 very strong π-bonds as well as a strong σ-bond). So one would tend to find nitrogen in the atmosphere rather than in solid minerals. (This is in contrast with oxygen, which of course happily forms a huge series of silicate minerals, oxides, etc.)

All the elements up to and beyond iron will have been present in the dust and gas from which the solar system condensed so, rather than formation, this issue is more about fractionation, i.e. which ones became concentrated in particular planets, and then in what part of the planet (atmosphere, crust, mantle core). Sulphur forms a range of compounds with iron, some of which are not of fixed composition, i.e. solid solutions or alloys. From the article it seems they think sulphur is a major ingredient in the Martian core due to the composition of iron meteorites and also, I presume, their assessment of the density of the core from seismology.   

  

Edited April 27, 20232 yr by exchemist

A truly excellent reply. Clear, compact and pretty complete.

+1

I would imagine that a lot of the differences between Earth and Mars are down to the relative sizes. The smaller size of Mars would mean that it cooled quicker, from a less hot starting point. The Earth, hotter, for a longer period, would mean that the heavier elements would have more oportunity to sink to the centre. It's thought that the Earth was hit too, by another body, forming the Moon. That would have added to the heat. 

So Mars came together in a cooler event, and cooled quicker, allowing lighter elements to linger in the core. 

(all of that is my own speculation/opinion, I'm happy to be corrected)

1 hour ago, mistermack said:

I would imagine that a lot of the differences between Earth and Mars are down to the relative sizes. The smaller size of Mars would mean that it cooled quicker, from a less hot starting point. The Earth, hotter, for a longer period, would mean that the heavier elements would have more oportunity to sink to the centre. It's thought that the Earth was hit too, by another body, forming the Moon. That would have added to the heat. 

So Mars came together in a cooler event, and cooled quicker, allowing lighter elements to linger in the core. 

(all of that is my own speculation/opinion, I'm happy to be corrected)

Possibly.

Here is a link to the original PNAS article: https://www.pnas.org/doi/full/10.1073/pnas.2217090120 

The "Interpretations" section is the most interesting. This runs through the various compositional ratios of Fe, S, O, C and H that they considered, in trying to match the observed seismic data. Interestingly - and rather counterintuitively to me - they alight on H as needing to be present to avoid having what they consider an unreasonably large proportion of S in the mix. This could fit your idea of cooler conditions and  a faster congealing, compared to the Earth.

But they don't themselves speculate on formation processes for the core. This work seems to be offered as food for thought, for other planetary physicists and chemists to study. 

21 hours ago, exchemist said:

Possibly.

Here is a link to the original PNAS article: https://www.pnas.org/doi/full/10.1073/pnas.2217090120 

The "Interpretations" section is the most interesting. This runs through the various compositional ratios of Fe, S, O, C and H that they considered, in trying to match the observed seismic data. Interestingly - and rather counterintuitively to me - they alight on H as needing to be present to avoid having what they consider an unreasonably large proportion of S in the mix. This could fit your idea of cooler conditions and  a faster congealing, compared to the Earth.

But they don't themselves speculate on formation processes for the core. This work seems to be offered as food for thought, for other planetary physicists and chemists to study. 

Thanks, I'll take another look at that section.