Chronology; Mars vs The Moon

Who's surface is older? Who's oldest? The smart bet is on Callisto, but you never really can tell. It could be Venus, but not Venus's surface. That is clearly young. The chronology of the early solar system is a puzzle to which pieces are constantly emerging but most remain missing. Earth is older than The Moon, we can say that, but how old is Mars really? Is it smaller in part because it started later? Because Jupiter ate all it's food? Solid bets, but still unknown. 

Mars is actually dated 4.1-3.7 bya semi-officially, Luna (The Moon) is dated 4.41 bya. Callisto? actually just 4.0 bya but the number is little more than a placeholder. We know more about Mars and Luna, but even still we don't know enough to be certain that Mars is younger. These numbers have a large amount of uncertainty in them, but just like we can be sure that Earth is older than Luna, and Callisto is younger than Jupiter, this IMRAD will take a step toward determining the eldest between Luna and Mars.

In the introduction we find that dating by crater counting is actually limited to 3.92 bya. That explains why the dates for Callisto and others bunch up at around 4. You need secondary evidence to go older, and that comes mostly from superposition and modeling. An old thing overwriting some of another old thing by superposition means that the overwriter is older, and if you can figure out how much older then you get a range. Luna is used as a baseline in all crater counting. As you would guess there's a lot of nuance included in that since we don't actually know if Luna is an ideal baseline. The environments in the solar system vary too widely. 

Here's a problem; Mars actually has way too few big impacts compared to Luna. There's obviously something amiss. Compared to Luna Mars should have 40 big ones, Mars actually has 7, and the seventh is debatable. Smaller-big craters actually deliver the expected ratio where Mars has a lot more. Part of the issue is that even 40 is a small number to statisticians and this kind of research is heavily reliant on statistical math. It could have something to do with Jupiter, it could be that Luna was hot and squishy and really good at exaggerating how big a thing hit it. Could be all of that and more. 

The paper strait-up skips to results before methods, because their results are pretty straight forward and brief. "The observed Mars number is significantly smaller than the scaling would predict." Meaning Luna is either older, has/had some property that makes big craters, or maybe Mars is bad at catching impactors. But for sure Mars got hit less. 

Now the methods. As promised, small number statistics put an umbrella of uncertainty on all this. A subtilty the team peppered all over the paper is that the squishy factor, whether Mars or Luna was hot at the time of impact is currently testable. Some of the radiogenic isotopes usable for dating exist somewhere in a hard-drive, both worlds have seen probes. And there is probably other data that could confirm or eliminate the possibility of any squishyness. Someone could be researching this right now.  

In the discussion the emphasis is that Mars and Earth do not catch the same number of impacts today, not even close. So obviously the time of big impacts probably had two wildly different environments. Keep in mind we don't actually know the positions of either Earth or Mars at that time, which really puts a hard drag on the ratio of Luna vs Mars even meaning what we want it to mean, aging. 

In the end this IMRAD caught an interesting imbalance and aggravated the questions that came up with it. It didn't make any hard claims other than Mars got hit less than Luna. But questions as to the reasons why are defined clearer now, so the research process continues with better focus. 

 The book has some clever tricks to make a petite and aesthetic home garden and it teaches well. 

However, it's greatly hampered by a lack of imagery. Cartoons are present but there are not nearly enough of them for a DIY non-fic. Pictures are absent but should be abundant. There are other issues that may not carry over from the ARC, and it would be a strong DIY if these issues are resolved.

 

The names of profound WW II men are known, but not for the deeds within this history. Certain events were perquisite to the final product. 

Amy Shira Teitel writes with a style that can easily be reformatted into a bulleted list; which for a non-fiction works.

 IO ELECTROLYTIC SNOW.

IO is far far more awesome than the poorly informed suspect, and the best informed know. It's just shooting out copious ions into the Jovian environment via regular volcanic eruptions that can be ten percent of the planets area. The Flux Tube and Plasma Torus are potential energy sources that with current tech could potentially power a permanent satellite, or more. 

The ions that IO is pumping are strong ones, mostly oxygen and sulfur in the form of SO2. However this IMRAD is looking for other combinations, such as S2O and other poly-sulfur oxides, because again, Oxygen and Sulfur are very reactive, and will do something with any molecule, especially ions, that they meet in Jupiter's extreme environment. 

In the introduction the plan is to match color, spectroscopy and where these things show up on IO's map. Non-SO2 molecules should appear in redder spots.

In the methodology section the team specifies using the Hubble's spectrograph to take 8 samples of spectroscopy mixed with some Galileo data. To pull facts out of the data a deep knowledge of spectroscopy is needed, so there is a whole definitions section with subsections to help folk who want to recreate or interrogate the results. You don't have to read any of it if you don't want to.

The results start in section 4.1. Unsurprisingly a lot of equatorial SO2. SO2 will freeze straight out of the void at these locations, producing a frost or less likely, a snow. The results are somewhat inconclusive, which was expected, but it looks like they found among other things, Red-Sulfur-Glass, Na2S, S2O and maybe iron ions. The red sulfur glass in particular is a fun idea. This morphology of sulfur seems to be unique to IO. This S4 ice-glass seems to be part of all the reddest areas on the surface of IO.

At the end the team really does not stick their necks out too much, just speculating about the sulfur glass. The papers expressed purpose was to explore a spectroscopy range that had not been looked at yet, and to that end it was fully successful. However the exploration did not really conflict with Voyager or Galileo data so much as reinforce it, so the conservative conclusions are a good thing. 

 Venusian Snow. 

Venusian snow is an exciting thing in my opinion. It is metallic, and implies catalytic chemical reactions in the Venusian atmosphere. It's not an especially new thing, it's been observed long enough that various persons have conflicting opinions about it. This IMRAD is written to settle some debates.

In the introduction the paper explains how the snow is observed, by radar, and owing to the properties of radar and what it observes attempts to infer things are made. There's a huge range of possibilities, which are included. It ends with a brief note about the elevation of the snow. The elevation is synonymous with a given temperature and pressure. The snow may only be stable at a certain environment, but the implication is that it exists at at least two elevations.

In the methods section the data came from Magellan, but was fed through some neato-skeeto computer program someone made. 

In the results section the snow line is seen to vary in elevation by 3.5km. The mountain range in question, Maxwell Montes is 11 km tall, Mt Everest is 8.8km tall. So this is the peaks of a mountain range with a little less than a third from the top eligible to catch snow. There is much notation concerning potential flaws in the data which can undermine the conclusion. DAVINCI will be able to make a better observation than Magellan did.

The second section of results is arguing a case for 'snow-shadow'. Rain-shadow on Earth refers to the way mountains catch more rain than surrounding valleys by interfering with wind, compressing humidity, and forming a downwind low pressure pocket. None of those mechanisms are super safe to apply to Venus, but the team observes where they can see the metal-snow, and then what physics can bring it about are free-game to speculate on. They didn't do the speculating from what I see, they just fired the starting pistol.

In the third section of results the nit-picks of potential misinterpretations of the radar data are pre-addressed. Basically the thing that can blow up this whole paper is a radar reflectivity or emissivity misinterpretation, so they are making sure everyone knows they double checked.

In the first section of the discussion they lob off a few possibilities that they do not think is true. If the Magellan data is bad, then the snow-line might be flat at a narrow elevation. If the Snow-line turns out to be an isotherm, then a lot of probes have been misreading surface temps. If the snow prefers to stick to certain rocks than others, then it should look messier than it does. It is not ruled-out that the snow may have come from an ancient incident and is not part of an ongoing process.

In the second section of discussion, assuming that all the data is good, then it must be the atmosphere dictating where snow is and isn't. This is reinforced by recent papers that are noting that the atmosphere below the cloud-deck changes in composition both periodically, and with latitude. So Maxwell Montes might be at a good latitude to catch snow.

The conclusions are many, but kind of revolve around the theme that the atmosphere is making snow, not plating metal on a rock-type as a chemical reaction. And also that there is a snow-shadow reaction, which opens up a new trail-head to study. It is possible an ecology exists, where the snow catalyzes atmospheric reactions, and the atmosphere makes, among other things, snow, implying that other chemical abundances may be seasonal, or latitudinally related to the snow. Possible negative and positive feedbacks.

 "Big impacts that could cause real damage are really rare."-Davide Farnocchia 

So this is an example of what Von Karmen lectures have become. I'm going to watch them regardless, so I may as well share. However there isn't much I can do to set it up, they are already simplified to the max. So enjoy the link.