Posts Tagged ‘fissure vents’

Some Thoughts on Transient Lunar Phenomena: 2

July 29, 2017 1 comment

In the previous post of this series, I made the point that Transient Lunar Phenomena (henceforth referred to as TLP) are real and are still poorly understood. I also stated that one type of them, characterized by small flashes lasting for no more than a few seconds, are almost certainly due to meteor strikes on the lunar surface. But what about all those rather infrequent colored mists and luminous discharges that seem to be concentrated in a few locales on the moon?

Well.. after denying their physical existence before the late 1950s, professional astronomers seem to have gradually come to accept them as real. Of course, there are still some credentialed idiots.. I mean astronomers who love to create every elaborate explanations about how they are an artifact of observation. But enough about those worthless hucksters. Anyway, we are still stuck with trying to understand what process causes them in the first place.

To date, four explanations are usually offered to explain TLPs. Two of them, namely ‘Impact Events’ and ‘Unfavourable Observation Conditions’ have already been discussed with the prior being true for one category of TLPs and the later being an excuse for elaborate hand-waving by sophists. And this leaves us with the other two explanations: ‘Outgassing’ and ‘Electrostatic Phenomena’. While both are feasible and not as mutually exclusive as you might think, they still do not answer the central question- what are we observing in the first place?

The most poorly answered question about TLPs which last for more than a few seconds has always been- “what is the chemical composition of whatever is being observed?”. The simple answer to that question is that we either don’t know for sure or have mutually contradictory data. But why? How come we have tons of data about composition of the atmosphere of Venus, Mars, moons like Titan and other planets but very little information about temporary changes in the chemical composition on the lunar surface that accompany TLPs.

It comes down to two factors:

(1) Almost all studies on the chemical composition of non-terrestrial bodies is done by using some forms of spectroscopy. In other words, measurements of the chemical composition of non-terrestrial bodies are almost all indirect measurements of how photons of some wavelength interact with atoms (or molecules) of whatever is being studies. A secondary effect of being reliant on spectroscopy for such studies is that the equipment to do that is far scarcer than for simple observation of those bodies at optical or near-optical wavelengths.

(2) A lot of the scientific interest and funding for studying the moon disappeared after the late 1960s.Today, there are very few financial and instrumental resources for studying phenomena on the moon, especially one as ephemeral as TLPs. I should also point out that TLPs, while vaguely accepted by the professional astronomical community, are still not seen as “respectable” research especially in a world where scientific research has become another extension of neoliberal ideology- with an emphasis on “productivity”, “metrics” and being non-offensive to “authority”.

But we still have not touched what I believe is the central question about TLPS, namely what are they made of- chemically speaking? Or perhaps a better way to phrase that question is- what would be the likely chemical constituents of TLPs?

Before we tackle that question, let us reacquaint ourselves with some basic facts about conditions at the lunar surface and the moon in general. Firstly, the moon has basically no atmosphere worth mentioning and therefore any gaseous emissions from the interior of the moon will quickly dissipate into the near vacuum which prevails near its surface. Contrast that to earth where, for example, the gas and dust from a volcanic eruption will hang around for days. Secondly, the lunar surface has not witnessed extensive volcanism for at least a billion years. There is however evidence that minor volcanic eruptions on the moon have occurred as recently as 50-100 million years ago.

Thirdly, the moon is substantially smaller than the earth and contains a far smaller metallic core. The point I am trying to make is the moon should be geologically far more deader than it is in reality. Then again, that is what most people used to believe about Pluto and Ceres till space-probes visited them in the previous 2-3 years. To put it another way, a lot of what astronomers thought they knew about factors responsible for geological activity on non-stellar celestial bodies is, at best, incomplete. And this brings us to the issue of what we know about the composition of gaseous emissions from the moon.

One of the first spectrograms of such an event, in 1958, suggested the presence of something containing carbon in the emissions. Observations by manned and unmanned spacecraft have also shown that some regions of the moon give of far more Radon-222 than others. Curiously enough, these areas of the moon happen to be TLP hotspots. To make a long story short, the idea that some regions of the moon often release small amounts of gases is now largely accepted. So far so good.

But here comes the curveball.. all gases known to emanate from the lunar surface (nitrogen, argon, radon, helium, methane?) are colorless! As you might recall, TLPs were first noticed because of changes in luminosity and color in regions with a size of least 3-4 square km. Which means that whatever is released during these events is either one (or more) colored gasses or some form of dust with a particle size that gives it some color when exposed to sunlight. On earth, most of the color in the smoke of volcanic emanations is caused by various compounds of sulfur or nitrogen and basalt dust which absorb light of a higher wavelength than orange.

Given that the laws of physics are constant throughout the universe and chemical composition of the moon is unlikely to be radically different from Earth- it stands to reason that the colors and luminosity changes seen during TLPs are due to the release of emanations with more than a passing similarity to those from some volcanoes on earth. Yet, there is no evidence for currently active volcanoes (as we would define them) on the moon- even though we know the location of more than a few extinct ones. The lunar surface also has atypical and small volcanoes.

TLPs, in my opinion, are due to the release of gaseous compounds (containing sulfur and nitrogen) and basaltic dust by volcanic features similar to Fumaroles and Fissure Vents on Earth. Their distribution on the moon might be linked to the presence of especially thin and fractured lunar crust. Of course, accepting such an explanation would mean that a lot of what we currently believe about the internal structure of moon and other celestial bodies of similar sizes is incomplete. Then again, we could always preserve existing dogma by ignoring such phenomena or pretending it not real.

What do you think? comments?