Talk:Martian polar ice caps

Citation questions

Are there any new findings by reliable sources like NASA that are after 2006? Afvasquez (talk) —Preceding undated comment added 18:47, 3 October 2016 (UTC)

Citation needed for citation 15 and 16 Afvasquez (talk) 18:52, 3 October 2016 (UTC)

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Disputed

On the sentence in the introductory paragraph:

When the poles are again exposed to sunlight, the frozen CO2 sublimes, creating enormous winds that sweep off the poles as fast as 400 km/h

citing Hess, S., Tillman, J. (1979) for this claim. Reviewing this paper, I believe the section used as evidence for this claim is as follows (my bolding):

[H$_{2}$O] is, therefore, a minor [atmospheric] constituent, and its condensation and evaporation will differ markedly from that of the major constituent, CO$_{2}$, in several ways.

First, the basic problem of the transfer of H$_{2}$O in an evaporation-condensation cycle from a solid state at one place on the planet to a solid state at another vastly more difficult than the corresponding for CO$_{2}$, since, at the minimum, $10^{4}$ times as much CO$_{2}$ as H$_{2}$O is not removed in a single cycle the ratio becomes correspondingly larger, and an unreasonably strong wind system would be required for the effective transport of water vapor. For example, one might assume, as an extreme upper limit, that during the disappearance of one cap and the growth of the other the entire $10^{-3}$ g of water vapor above each square centimeter of the disappearing cap is transported to the growing cap and deposited there daily as frost. (Such a process would require net north-south winds of about 500 kilometers per hour blowing steadily for perhaps 100 days, combined with complete vertical mixing daily at each end.)

I believe this passage has been misinterpreted in several ways. My interpretation is that this is a "mental model," so to speak, about the upper end of energy/wind needed to transfer some volatile from one pole to the other. Second, the wind speed quoted here refers to the wind needed to transfer the full amount of Mars' evaporated water in a pole to the other pole. While this does have to do with the sublimation of a volatile, its not the sublimation itself that causes the wind, just that this is the amount of wind needed to explain the mental model.

I hope I've been clear in my explanation. Thanks

You are actually quoting Leighton & Murray (1966), which is not cited by the article. Jimmarsmars added the citation to Hess, Henry & Tillman (1979), but the statement existed prior to that, so who knows where it came from. WolfmanSF (talk) 04:22, 18 November 2017 (UTC)

The statement originated with Mlm42 (contribs) in the Mars article on 17:27, 17 March 2006, without a citation. It is still present there, as well as in the Atmosphere of Mars article. Perhaps it did come from Leighton & Murray (1966). WolfmanSF (talk) 05:05, 18 November 2017 (UTC)

This paper and this paper both discuss wind speeds of ~ 30 m/s (~ 100 km/h) near polar cap edges, but due to thermal gradients as well as CO2 sublimation. WolfmanSF (talk) 07:29, 18 November 2017 (UTC)

External links modified (January 2018)

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winter in one hemisphere causes freezing in both?

"when one hemisphere experiences winter, approximately 3 trillion to 4 trillion tons of carbon dioxide freezes out of the atmosphere onto the northern and southern polar caps" Is this correct? Wouldn't the other hemisphere be in summer?--2607:FEA8:D5DF:F945:8C09:818D:3BA8:8AAE (talk) 23:28, 25 October 2019 (UTC)

You are correct; that has been clarified. WolfmanSF (talk) 23:40, 25 October 2019 (UTC)

Smectite clay, not water ice?

While it is premature to rewrite this Wikipedia entry now, this AGU research letter posits that smectite clays are a better explanation than buried salty ice for radar returns from the Martian south pole. The north pole isn't mentioned in this study, subsequent studies may.

• https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2021GL093618

Wikipedia should not "take sides" before more scientists weigh in. However, if the controversy persists, the Wikipedia entry should acknowledge the dispute. Many of us want Mars to have lots of water ice, but that doesn't mean it is actually there.

Referred to by these news reports:

• https://www.space.com/mars-buried-polar-lakes-frozen-clay
• https://www.scientificamerican.com/article/buried-lakes-on-mars-may-just-be-frozen-clay

KeithLofstrom (talk) 20:46, 2 August 2021 (UTC)

North Polar Cap - Ambiguous Statement

The statement... "The extra sunlight causes the ice to melt, so much so that it could cover parts of the surface in 10 m of ice"... does not make sense. How much of the surface is "parts"? I suspect that it should say either "... would cover the entire Martian surface in 10m of ice", or perhaps "... the entire northern hemisphere in 10m of ice. Given the dimensions of the northern ice cap, both seem reasonable. At least I try (talk) 16:24, 14 August 2021 (UTC)