In the early 1990s I wrote Red Gold, a novel that involved fraud and murder during a futuristic colonization of Mars. To expose the fraud, I needed a totally unexpected discovery, which required something that was not part of the standard theory. At this point, I had done a little research on Mars, so I had some knowledge of what the puzzles were. After a little thought, I decided to have my discovery to be that of an original reduced atmosphere. I shall explain that below, but first the problem it solves.
One of the great puzzles of Mars is the remains of what can only be interpreted as massive fluid flows. Some flows were extraordinarily large, up to 100 million cubic meters per second, and which carved out massive valleys up to 200 km wide. However, these flows did not last for long. Other examples show meandering river systems that probably flowed for something like a million years. Some started in the southern highlands and were probably amongst the coldest places on Mars. Worse, the temperature of Mars today averages at minus eighty degrees C, and the star now puts out about 30% more energy than it did then.
The geologists argue that the gases coming out of a volcanic vent are in equilibrium with the rocks; the rocks then are the same as now, so the gases would be the same. Accordingly, the gases would be carbon dioxide, nitrogen and water. (These are called oxidised gases because they have no hydrogen attached.) The scientific literature is still cluttered with models that argue that enough carbon dioxide would trap enough heat to melt ice. That is not possible because if you had enough carbon dioxide it would exceed the critical pressure at those temperatures and the carbon dioxide would liquefy and rain out, thus lowering the pressure, trapping less heat, thus raining out more carbon dioxide, and eventually snowing it out at the poles, to get reasonably quickly to where we are today. Without a lot of arm-waving, there is no reasonable mechanism to get the temperatures high enough to melt ice.
My proposition was that the original gases were reduced, i.e. water, ammonia and methane. The significance of that is that ammonia dissolves in ice to form an ammonia/water solution that is liquid at minus eighty degrees C, hence snow would partially liquefy and start the flow. (The cause of the more massive flows is similar, but with some specific details that are outside the scope of this post.) Methane is a somewhat more powerful greenhouse gas than carbon dioxide so some elevation of temperature is expected. This scenario is not believed because Sagan produced a paper that argued that ammonia in the atmosphere would only last decades unless there was a protective smog, similar to what nitrogen and methane produces on Titan. We could reasonably expect such a smog, and of course the bulk of the ammonia would not be in the atmosphere; it would be in the water. What would happen next would be that the UV radiation would gradually oxidise the methane to carbon dioxide, and the waters would scrub that from the atmosphere to let the ammonia form ammonium carbonate, which would eventually form urea, which, of course, is a fertilizer. That was the discovery in my novel; an important discovery because the fertilizer is what permitted the settlement to at least be able to feed itself. Thus if the gases came from volcanoes that lasted for a certain time, the river flow might also last a comparable time, and in fact the evidence is, they did.
So, where did our atmospheres come from? You will see persistent arguments that they came from comets, but that is wrong because the deuterium levels in comets are far higher than that in our water. Others say asteroids, but other isotopes are wrong and the water levels are low. There is also the problem the ratios of the various volatiles on the three rocky planets are all different, so they had to come from different sources, or be accreted in some different way.
I made the decision that the rocky planets could only accrete solids, and water, from the accretion disk. The water was necessary to start the accretion, as the reason the dust held together was that heat processing had made cements. (One of the original Roman cements was heat-processed silicates from Vesuvius.) The nitrogen and carbon we have were accreted as nitrides and carbides from the original accretion disk (and these are still found in enstatite chondrites) and were made by reaction with water underground and emitted in volcanoes/fumaroles.
It was amusing trying to write this up as a scientific paper. The referees either scoffed at it, seemingly thinking cement was carefully made and only came in bags from hardware stores. (Cement for construction is precisely made to avoid warping, etc, but if you are merely trying to grow a rock, that is hardly important.) And everybody “knew” that it was proven that carbon dioxide came out of volcanoes. However, in my opinion the truth of a theory lies in the observational evidence, and I cited two references that they ignored. The first showed that certain rocks from Isua, Greenland, had trapped local atmosphere abut 3.8 billion years ago, and the gases were largely methane. There are also rocks from Barberton, South Africa, 3.2 billion years old, that contain ancient seawater, and these have surprisingly high ammonia content, particularly since the salt levels are high (due to hot rock that enclosed the liquids boiling off some of the water, and almost certainly some of the ammonia). So if ammonia could still be present in Earth’s oceans 1.3 billion years after the planet formed, why was it so impossible for Mars to have ammonia about the same time the volcanoes were mainly active?
The problem was, I was proposing a theory that was chemically based, and the referees were physicists, with very little chemical background. Actually, it got worse. There is an industry among these physicists in doing computations on the formation of the solar system, and I was told no paper would be accepted unless I had computations that predicted the structure of our solar system. Actually, I had, had they bothered to read the text, although I needed a constant, namely the ice point in the accretion disk. (Actually, they need that too.) The standard method is to start with a huge distribution of planetesimals, and let gravity accrete them. They have no idea how these planetesimals form, so they start with things big enough to have gravitational interactions. I had a temperature dependent differential equation, and planets turned up where the temperatures were optimal for that particular mechanism, and there were different mechanisms in the right places for all the planets.
Anyway, enough of that. My theory for planetary growth actually predicts the different compositions of the planets as far as we know and makes a number of further predictions, including no possible life under the ice of Europa. (Essentially no nitrogen and carbon, and no mechanism to make phosphate esters.) And I made predictions, including the existence of urea (or what it has degraded to) underground on Mars. So, my novel has the rather remarkable claim to fame that my own work falsifies the basic premise of the novel, that the discovery was unexpected. Or does it? Since nobody is taking any notice of the theory, maybe not. And as an added twist, in a later revision of the story I had a dig at certain referees by pointing out that a scientist had predicted this, but thanks to refereeing it only got published where nobody would see it.
Now for a quick commercial break! On June 2, for a week, Red Gold is on a kindle countdown discount (http://www.amazon.com/dp/B009U0458Y). If anyone is interested in Planetary Formation and Biogenesis, that is available at http://www.amazon.com/dp/B007T0QE6I, however this is not light reading, and is only for those who are really interested.