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Draft your Contributions

Edit of Lead Paragraph

The detection and potential presence of methane in the atmosphere of Mars is of interest to many geologists and astrobiologists, since methane may indicate the presence of microbial life on Mars, or a geochemical process such as volcanism or hydrothermal activity.

Since 2004, various Martian missions and observational studies have taken measurements of methane on mars. The data varied widely in space and time, reporting trace amounts of methane spanning from 60 ppbv to under the detection limit (< 0.05 ppbv). The validity of the data remains under scrutiny due to the wide range of findings and uncertainties inherent to the detection methods themselves. Potential sources and sinks of methane on Mars along with an explanation for the enormous discrepancy in the observed methane concentrations are still unknown and are under study. No such theoretical system for a methane cycle has been successfully identified. Definitive confirmation of the presence of methane on Mars remains to be seen.

Draft of SOFIA/EXES Content

Martian methane has been the focus of significant interest in the scientific community because of what its source could say about the planet. Potential sources include living organisms and geological processes such as hydrothermal activity or serpentinization.

Types of Observations

There exists two primary categories of astronomical methane detection methods: orbiter measurements made from satellites orbiting a planet and ground-based measurements made by an instrument located on the surface of a planet. Note that Martian measurements in either category may be taken from either Earth or Mars.

The nature of the measurement also contributes to the type of uncertainties that may be present in the resulting data. For example, a ground-based methane measurement from Earth looks through Earth's atmosphere. As a consequence, contamination from terrestrial methane is introduced into the measurement. Additionally, due to the distance between Earth and Mars, such measurements require a high signal to noise ratio (SNR). When processing data, such issues must be taken into account.

Orbiter Observational Results

Martian methane detections that have been made have varied across seasons, location, and Mars local time. The Stratospheric Observatory for Infrared Astronomy (SOFIA) was a mission that made spectral observations of the Martian atmosphere from Earth's stratosphere. SOFIA is a NASA Boeing 747 SP aircraft outfitted with the Echelon Cross Echelle Spectrograph (EXES) and a 2.7 $\mu m$ diameter telescope. In 2016, SOFIA took spectral measurements of Mars' northern hemisphere during the Martian summer. The regions and seasonal timing of measurements aligned with previous methane measurements to explore local changes across time. When processing the data, care was taken to focus on Methane's 7.5$\mu m$ spectral line in order to minimize interference from Earth-based methane spectral lines. Additionally, long observation times were used to increase the SNR.

Findings

No definitive measurements of methane were made during SOFIA's 2016 mission. A methane plume of 20-40 ppbv was detected over Terre Sabae. When the same region was checked using data from SOFIA, no methane was identified. Additionally, previous detections over Nili Fossae and Syrtis Major were met with more null detections by SOFIA.

Reconciling Results

Variations in methane values detected suggest a methane cycle on Mars while other reports have not found definitive evidence of methane on Mars. To explain swings between the presence and absence of methane, scientists have explored potential explanations for how methane could be produced (a methane source) and removed (a methane sink) in alignment with the data.

It has been proposed that meteor showers may be introducing small amounts of methane to the Martian atmosphere, explaining the highly variable detection patterns. However, no pattern has been identified relating plume detections to recorded meteor showers.

Photochemistry

Photochemistry has also been explored as a possible methane cycle explanation. Methane, when given enough time, will react with other substances or decompose into other molecules. Such a photochemical process results in methane concentrations naturally decreasing. Ultraviolet radiation can drive decomposition or reactions with other molecules such as water vapor or ozone.

Photochemical models suggest that the lifetime of methane on Mars should be between 300 and 600 years. However, such a lifetime does not explain the 2013 observations such as the methane plumes and subsequent dissipation as recorded by the Curiosity Rover in Gale crater. Such an event would require much faster removal than that predicted by photochemical lifetimes. Possible explanations include erroneous data or additional methane sources and sinks.

Explanations for possible methane sinks include dust storms and reactions with the Martian regolith. Dust storms create electric fields that can result in the decomposition of methane, producing ${\ce {H_{2}O_{2}}}$. However, data that has been collected does not reflect the ${\ce {H_{2}O_{2}}}$ levels that would be anticipated, bringing such a hypothesis into question. Oxidants present in the regolith reacting with methane are another possible explanation. Again, however, models found that the atmospheric interactions with the regolith surface are not long enough to cause the removal necessary to explain the observations.

Atmospheric mixing has also been considered as an explanation for methane dissipation. The day-night cycle, for instance, causes the planetary boundary layer to grow during the day and shrink during the night. As a result, such a process could explain high concentrations of methane measured at night. A model suggests that such mixing would not be a sufficient explanation, requiring some other physical process to explain dissipation of methane plumes.

Assignment 2

Evaluating Content

Questions

• Is everything in the article relevant to the article topic?
• Is there anything that distracted you? Is any information out of date?
• Is anything missing that could be added?
• What else could be improved? Is scientific information presented clearly, accurately, and without jargon?
• Does the article link to other Wikipedia articles for related topics?

Comments

Nothing about the article seems outright irrelevant. However, there are a couple of concepts that could be better integrated. For instance, the discussion surrounding the reduction of carbon dioxide into methane is introduced without much context. It might be better to first mention that methane could be generated from a reaction involving things that are already present on mars (like carbon dioxide and hydrogen). Such a reaction could then be a potential source of methane if it is present.

There are a number of recently published articles that are cited which is good. However, there are also several articles spanning from 2004 through 2009 (references 8, 16, 17, 18, 21, 52, 58, 64, 70, 71, 73, 75). It would be good to ensure that such references are also paired with more modern references.

One thing I think is missing in this article is a section describing how methane measurements are made. The following discussion points would be incredibly helpful:

• Discussion of the instruments themselves (ex. spectrometers)
• Discussion of the measurement error different instruments are prone to.
• Discussion of how the quality of a measurement is impacted by where the measurement is taken from (from orbit, from Earth, or from the Martian surface).

Transition to a discussion on the specific topics that the article focuses on, I would say that the article feels more like a discussion of possible explanations for what might be generating methane. Additionally, the article seems to largely confirm the presence of methane. By bolstering discussion of the measurements and their uncertainty, the article would at the very least be equipping readers to evaluate the rest of the article more critically.

The scientific discussion in the article didn't seem overly opaque to me. Where there were technical topics presented, links to other wikipedia pages were often provided. However, one trouble spot I found was that the discussion of isotopologues of methane could use a bit more explanation. A link to what 'isotopologues' are was provided, but no discussion was provided about which isotopologues would be connected to certain potential methane sources (geophysical or biological).

Another addition that I think would be useful would be a sense of Earth-centered scale. As a reader unfamiliar with the topic, 7 ppbv is not 0, so it seems significant. Then when a concentration 60 ppbv is mentioned, that sounds like a massive spike. However, once you realize that Earth has methane concentrations of 1921 ppbv, values like 7 ppbv are put into perspective as very small amounts. I feel that adding that sort of information would be useful.

Evaluating Tone

Questions

• Is the article neutral?
• Are there any claims that appear heavily biased toward a particular position?
• Are there viewpoints that are over-represented, or under-represented?

Comments

I do not find the article to be neutral. For instance, statements like "It is estimated that Mars produces 270 tons of methane per year," are made without a corresponding counter-argument or acknowledgement that the statement is an estimate made based on detection values that have not been unambiguously confirmed.

Another example comes from the article lead where the article point blank states that the methane that is detected is "...rapidly removed from the atmosphere by an efficient, yet unknown process." Such a statement assumes that the methane being detected is actually there and not the result of measurement error, something that is a distinct possibility.

Additionally, a large portion of the article is dedicated solely to explanations for what is producing methane on Mars. While such discussion is important and interesting, it should not dominate the article. To better balance the tone of the article, more language should be embedded into the explanations to highlight that the methane measurements remain questionable.

Evaluating Sources

Questions

• Check a few citations.
• Do the links work?
• Does the source support the claims in the article?
• Is each fact referenced with an appropriate, reliable reference?
• Where does the information come from?
• Are these neutral sources?
• If biased, is that bias noted?

Comments

Specific Citation Information:

• Reference 4 is not available anymore (404 Error): "Martian Methane Reveals the Red Planet is not a Dead Planet".
• A number of the Nature and Science articles are behind paywalls. That is unfortunate for anyone not at a university or large scientific institution (most people). That is not a problem with the article, more of a larger scientific community issue. New York Times also has a paywall.
• Citation 23 seems interesting: "A sensitive search for organics (CH4, CH3OH, H2CO, C2H6, C2H2, C2H4), hydroperoxyl (HO2), nitrogen compounds (N2O, NH3, HCN) and chlorine species (HCl, CH3Cl) on Mars using ground-based high-resolution infrared spectroscopy"
• There is a broken in-line citation that references source 57 at the end of the "History of Detections" section. The hyperlink that should jump you down to the references section isn't property formatted.

There is a mix of references spanning scientific articles, popular news sites, conference papers, and instrument websites. Some examples of popular news sites that are included are Wired, Space.com, and The New York Times. These sources don't need to be removed. However, when used within the body of the text, it would be good to also find a peer-reviewed journal publication to pair with the popular news source. For instance, there are a number of statements that only cite Wired.com (citation 15). Adding additional scientific citations would be good to include with such statements.

One particular discussion point that seems lacking in references would be the Medusae Fossae Formation. The Wikipedia article mentioned that the formation is nearby Gale Crater (where the Curiosity Rover is located) and has been considered as a source for the methane detected by Curiosity. Only one source from 2019 was linked to that claim. It would be interesting to see what other sources say about the topic and if any more recent developments have been made.

Evaluating Talk Page

Questions

• Now take a look at how others are talking about this article on the talk page.
• What kinds of conversations, if any, are going on behind the scenes about how to represent this topic?
• How is the article rated?
• Is it a part of any WikiProjects?

Comments

The article is currently a C-rated article. Wikipedia acknowledges that the content needs updating.

The talk page has in-depth comments that highlight the need to revamp the article. DCCProf provides a long comment explaining that there are a number of unsubstantiated claims in the article and highlights how a number of recently published articles emphasize how the methane detections that have been made are not definitive.

I will say that the long and highly referenced comment rubs me the wrong way a bit. The author clearly has much to say about the article and has already gone through the trouble of identifying appropriate references. Despite such a stance, the editor claimed that they didn't have time to revamp the article. It is my view that making smaller edits on the parts that the person takes issue with would have been more fruitful than writing such a long and highly referenced complaint while leaving the public-facing article as is.