Talk:Natural methane on Mars

Wiki Education Foundation-supported course assignment

This article was the subject of a Wiki Education Foundation-supported course assignment, between 2 April 2019 and 28 June 2019. Further details are available on the course page. Student editor(s): Real YC. Peer reviewers: Gretashum.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 00:56, 18 January 2022 (UTC)

As the instructor for this course, I should comment that this page was *NOT* a page assigned to be written for the WikiEdu course and none of my students wrote it. Instead, student @Real YC extensively updated the Atmosphere of Mars page, making it a high quality wikipedia page. The Methane on Mars page was spun off and written by others and not reviewed by anyone in my class. I mention this because I don't consider the current version (22 June 2022) to be well-written, accurate, or suitably impartial. So, I have no desire to be associated with it.

There are several problems. The page uncritically over-emphasizes speculations about methane sources and sinks on Mars. The lead on the page fails to emphasize the primacy of the best data, i.e., the Trace Gas Orbiter (TGO) data, which is the most sensitive (and most temporally and spatially extensive) attempt at methane detection to date and finds no methane to high precision (upper limit of 20 pptv), which cannot be reconciled in any clear way with other claims of methane detection. The page fails to cite the relevant literature including critical literature, e.g., the paper by Gillen et al. (2020) showing no statistical basis for a seasonal cycle in current data from Curiosity Mars rover; or TGO papers such as Montmessin et al. (2021). And the page sometimes misrepresents the scientific literature. For example, it cites a 2010 conference abstract by Zahnle et al. supposedly in support of a speculation about clathrates as a source of methane on Mars, but a paper, Zahnle et al. (2011) "Is there methane on Mars?". (which is not cited) actually explains why clathrate sources are improbable and why some of the past claimed detections of methane are themselves doubtful. There are other problems with the page. But the above list should suffice to explain my low opinion of the page. (And no, I don't have time to overhaul this page myself at present, unfortunately). DCCProf (talk) 00:31, 23 June 2022 (UTC)

Note that there is now a possible explanation for the discrepancy: the methane detected on the ground might be quickly destroyed before reaching the higher atmosphere where the the trace gas orbiter could detect it. See [1](The Methane Diurnal Variation and Microseepage Flux at Gale Crater, Mars as Constrained by the ExoMars Trace Gas Orbiter and Curiosity Observations, Geophysical research letters, Vol 46, Issue 16, pages 9430-9438, John E. Moores et al) , found via [2](News post on NASA from 29 Jun 2021)

----~~ Camil7 (talk) 01:05, 20 March 2023 (UTC)

First, the Geophy. Res. Lett. paper is from 2019, so is outdated: it does not use the latest lower limit from TGO from Montmessin et al. (2021) in its calculations . Second, a speculative hypothesis that CH4 is peculiarly restricted to seepages in Gale crater that just happen to be where a rover landed but not elsewhere on Mars is a very ad hoc explanation. Another paper, Moores et al. (2019, Nature Geosciences), attempted to explain methane destruction and variability also. Let's delve into the details. This paper used a thermodynamic methane absorption significantly different from actual lab-based measurements and a timescale for methane destruction that was a free parameter, i.e, a made up number, with no physical basis from any lab data. With these assumptions of non-physical parameters, the paper constructed a curve-fit to the supposed seasonal cycle of methane on Mars. Recall that Gillen et al. (2020 in Icarus) subsequently showed that that the inferred seasonality from the data is statistically unsound anyway.

The devil is always in the details of the scientific papers, and news posts do not cover such details. In summary, several papers attempt to explain the conflict of no methane seen by TGO but methane reported from Curiosity rover. Unfortunately, explanations based on unphysical or cherry-picked assumptions do not meet normal standards of scientific justification, in my opinion. As more data are added, TGO could continue to push its lower limit on methane downwards, as it has done so far, so the mismatch could accentuate with time. DCCProf (talk) 01:49, 11 April 2023 (UTC)

A Commons file used on this page has been nominated for speedy deletion

The following Wikimedia Commons file used on this page has been nominated for speedy deletion:

• TGO's search for methane on Mars.jpg

You can see the reason for deletion at the file description page linked above. —Community Tech bot (talk) 14:51, 11 July 2019 (UTC)

Methane not found?

@DCCProf: I have tagged the article to highlight the issue. To those coming here to discuss, the issue at hand has been explained in detail above in the section "Wiki Education Foundation-supported course assignment ". –LordPickleII (talk) 20:14, 7 September 2022 (UTC)