Rate of shrinkage of the Martian Poles?

[Drifter]

My first post ... looking for some expert opinion.       Just a few questions about the Martian polar icecaps.

1) Like Earth, the Poles of Mars appear to be shrinking - Any predictions/calculations when the ice caps will sublimate away completely? ... or is that an impossibiity?

2) For future manned missions - being camped near a water source is essential .... are the icecaps likely to be a good source of pure drinking water when melted or will considerable purification be needed?

3)Will drilling into volcanic aquifers be the best source of pure drinking water for Martian Colonists of the future?  ... Evian/Volvic subterranean  reservoirs suggest volcanic action produces water as a bi-product which condenses and stores in subterranean pools and lava tube chambers - a source that won't have sublimated on Mars.

(Can't imagine Martian explorers and mineral engineers will want to be stuck camped near the freezing Poles all their time there - be nice to set up a bath house/sauna near hot geyser springs and bask on warmer dried-up beaches near the Equator on a summer break, eh? - just drill into the base of a nearby extinct volcano - Bingo ... pure water on tap!)😅

4) Some global warming deniers think Martian polar cap shrinkage suggests a Solar System phenomena at work at the moment - Is there good  hard core science data related to periodic cosmic radiations or planetary orbits that could explain how that could happen?

Related article:  https://www.space.com/33001-mars-ice-age-ending-now.html

Do members think there is insufficient data for scientists to speculate Mars is emerging from an Ice Age at the moment?

Check out the Youtube video reply in this piece:  https://www.skepticalscience.com/global-warming-on-mars.htm

 

 

 

 

[johnturley]

I raised this issue back in 2005, the circumstances of the 2005 November 7 opposition of Mars were similar those of  the 1973 October 25 opposition, however whereas in 1973 the south polar cap was clearly visible, I couldn't make it out at all in 2005. Originally I put this down to poor viewing conditions from my location in 2005, but I subsequently saw a Hubble Space Telescope image showing the SPC to be so small, that it would have been hardly visible through many amateur astronomers telescopes. 

At the time the Russian Astronomer, Habibullo Abdussamatov, head of the Pulkova Astronomical Obseravtory in St Petersburg cited this as evidence that the current global warming is being caused by changes in the sun. Mainstream scientific opinion however put this down to variations in the isolation of the planet  arising from albedo changes (not sure exactly what this means), rather than increases in solar radiation. I understand that BAA records of observations of Mars go back to the early 20th Century, so it would be interesting to look at records over the past 100 years. 

You refer to global warming deniers, I don't think any scientific opinion disputes that the climate is getting warmer, and man made CO2 emissions will have some impact, the main question is what is the primary cause. I used to be a bit of a sceptic regarding man made CO2 emissions being the primary cause, but in recent years have been coming round more to the opinion that this is the case.

John 

Edited September 23, 2020 by johnturley

[Drifter]

Cheers for taking the time to reply, John.

That sounds like a rather alarming decline in the size of the South Pole Cap - especially if you are a primitive Martian life form clinging to a dwindling water source for survival! - It would be nice to think primitive life exists there around the melting/sublimating edges of these caps … and in the sub-surface reservoirs creating the methane pockets of gas detected oozing periodically from the surface of the Planet. 

Now we have more sophisticated analytical equipment orbiting Mars, in the form of the Mars Reconnaissance Orbiter doing detailed deep radar scans of these ice fields(outlined in 1st Link) I guess Earth/Hubble observations from a distance provide more of an overview these days.🤨 No reason for people to throw away their gear and stop looking at Mars from Earth, eh?

Amazing to see the 'swirling pattern' in the northern cap giving clues on how the poles influence convection forces on Mars.

The mention of these Milankovitch Cycles sounds interesting. Wikipedia has the following: https://en.wikipedia.org/wiki/Milankovitch_cycles

Quickly scanning this synopsis it becomes evident polar shrinkage and climate change patterns can't be completely explained by these M Cycles … stratified data doesn't appear to be lining up neatly to convince scientists this is the total answer …. so many factors appear to be involved in climate change/planetary polar ice shrinkage ….  no get-out-of-jail-free card for climate change skeptics/human species/major polluters of our planet.😋

…. probably an indication this is something that is pretty much out of our control  … however, no reason not to do anything to help the Earth 'restabilise'. [Stop burning down the Amazon and other woodland areas and reducing our birth rate by 90% might help! … far more effective/cheaper than driving an electric car].

Do you think Mars having a thinner atmosphere will probably suffer greater from this type of effect? … and as the article adds "Mars has no moon large enough to stabilize it's obliquity, which has varied from 10 to 70 degrees." - not that it shifted much between 1973 and 2005!😆

[Drifter]

Breaking news on the BBC this week with regards the hidden lakes under the South Pole of Mars.

https://www.bbc.co.uk/news/science-environment-54337779

Not sure why scientists are concluding these lakes may be brine - can the radar scans determine that fact through thick ice? - If the water was synthesised as a bi-product of the liquefaction of rocks by volcanic processes and been trapped under the  icecap for millions of years - it's got a good chance it could be fairly fresh … The atmospheric effects of sublimation won't strip away trapped sources of water underground or under ice.

This strengthens the idea that with light filtering through and ice protection from the harsher effects of exposure to the recent Martian climate - maybe quite complex early lifeforms may have evolved and survived in this aquatic region.

Exciting times for explorers.

 

 

[Gfamily]

I think they can calculate the thermal gradient from space and work out the likely temperature at the relevant depth, which is below freezing point of pure water.

 

[Drifter]

Thanks for pointing me in that direction Gfamily.😆

Found an overview on the MARSIS radar system and in what conditions it will work.

 https://www.mps.mpg.de/planetary-science/mars-express-marsis

 

Footnote: The next step in subsurface radar for the 2020 Rover mission - RIMFAX apparently ….

https://www.cbc.ca/news/technology/mars-2020-rover-s-rimfax-radar-will-see-deep-underground-1.2739698 ...

 

 

[Drifter]

On 23/09/2020 at 12:33, johnturley said:

I raised this issue back in 2005, the circumstances of the 2005 November 7 opposition of Mars were similar those of  the 1973 October 25 opposition, however whereas in 1973 the south polar cap was clearly visible, I couldn't make it out at all in 2005. Originally I put this down to poor viewing conditions from my location in 2005, but I subsequently saw a Hubble Space Telescope image showing the SPC to be so small, that it would have been hardly visible through many amateur astronomers telescopes. 

At the time the Russian Astronomer, Habibullo Abdussamatov, head of the Pulkova Astronomical Obseravtory in St Petersburg cited this as evidence that the current global warming is being caused by changes in the sun. Mainstream scientific opinion however put this down to variations in the isolation of the planet  arising from albedo changes (not sure exactly what this means), rather than increases in solar radiation. I understand that BAA records of observations of Mars go back to the early 20th Century, so it would be interesting to look at records over the past 100 years.

John 

https://www.republicworld.com/technology-news/science/scientists-find-network-of-buried-salty-lakes-beneath-mars-surface.html

In this article, johnturley … there are a couple of pictures of the Martian South Pole …. The Mars Global Surveyor picture(date??) shows a significant area of surface coverage which you would probably be able to see from Earth in your observations.

However, the Mars Express picture (2018) shows an alarming shrinkage in the cap. I guess there could be seasonal variations which might explain some of the shrinkage  …. depending on time of year respective photos were taken.

It's a concern to those seeking Life on Mars that some Southern polar lakes might have evaporated away relatively recently … wonder if there are primitive lifeforms lying on the surface near recently exposed dried lake beds? Definitely an area worth exploring for the Life Scientists.

[CraigT82]

On 30/09/2020 at 07:14, Drifter said:

Not sure why scientists are concluding these lakes may be brine - can the radar scans determine that fact through thick ice?

Yes, as salty water had a very different relative permitivity (dielectric) to fresh water, which results in a different wave velocity

[markse68]

Aren’t the Martian poles mainly co2 dry ice? From school chemistry experiments I seem to remember dry ice sublimates pretty fast compared to water ice melting when plunged into a beaker of room temperature water. I think because of this the seasonal cycle on mars leads to drastic shrinking of the summer pole and i guess corresponding growth of the winter pole which gets reversed the next cycle? Is it unusual this year?

[Drifter]

Thanks for that nugget, Markse68 - Wikipedia seems to confirm a CO2/water mix … 

Main article: Martian polar ice caps

North polar early summer water ice cap (1999); a seasonal layer of carbon dioxide ice forms in winter and disappears in summer.

South polar midsummer ice cap (2000); the south cap has a permanent carbon dioxide ice cap mixed with water ice.[128]

Mars has two permanent polar ice caps. During a pole's winter, it lies in continuous darkness, chilling the surface and causing the deposition of 25–30% of the atmosphere into slabs of CO2 ice (dry ice).[129] When the poles are again exposed to sunlight, the frozen CO2 sublimes. These seasonal actions transport large amounts of dust and water vapor, giving rise to Earth-like frost and large cirrus clouds. Clouds of water-ice were photographed by the Opportunity rover in 2004.[130]

The caps at both poles consist primarily (70%) of water ice. Frozen carbon dioxide accumulates as a comparatively thin layer about one metre thick on the north cap in the northern winter only, whereas the south cap has a permanent dry ice cover about eight metres thick. This permanent dry ice cover at the south pole is peppered by flat floored, shallow, roughly circular pits, which repeat imaging shows are expanding by meters per year; this suggests that the permanent CO2 cover over the south pole water ice is degrading over time.[131] The northern polar cap has a diameter of about 1,000 kilometres (620 mi) during the northern Mars summer,[132] and contains about 1.6 million cubic kilometres (5.7×1016 cu ft) of ice, which, if spread evenly on the cap, would be 2 kilometres (1.2 mi) thick.[133] (This compares to a volume of 2.85 million cubic kilometres (1.01×1017 cu ft) for the Greenland ice sheet.) The southern polar cap has a diameter of 350 kilometres (220 mi) and a thickness of 3 kilometres (1.9 mi).[134] The total volume of ice in the south polar cap plus the adjacent layered deposits has been estimated at 1.6 million cubic km.[135] Both polar caps show spiral troughs, which recent analysis of SHARAD ice penetrating radar has shown are a result of katabatic winds that spiral due to the Coriolis Effect.[136][137]

The seasonal frosting of areas near the southern ice cap results in the formation of transparent 1-metre-thick slabs of dry ice above the ground. With the arrival of spring, sunlight warms the subsurface and pressure from subliming CO2 builds up under a slab, elevating and ultimately rupturing it. This leads to geyser-like eruptions of CO2 gas mixed with dark basaltic sand or dust. This process is rapid, observed happening in the space of a few days, weeks or months, a rate of change rather unusual in geology – especially for Mars. The gas rushing underneath a slab to the site of a geyser carves a spiderweb-like pattern of radial channels under the ice, the process being the inverted equivalent of an erosion network formed by water draining through a single plughole.

Throwing ideas around - wonder if the high velocity vortex winds of Mars are sinkholing layers of supercooled C02 and traces of water vapour at the Poles as a fairly thin layer periodically? Guessing these points (Wiki) below might also be causing the rapid Southern Pole shrinkage effect at times when a number of factors coalesce:

The comparatively large eccentricity of the Martian orbit has a significant effect. Mars is near perihelion when it is summer in the southern hemisphere and winter in the north, and near aphelion when it is winter in the southern hemisphere and summer in the north. As a result, the seasons in the southern hemisphere are more extreme and the seasons in the northern are milder than would otherwise be the case. The summer temperatures in the south can be warmer than the equivalent summer temperatures in the north by up to 30 °C (54 °F).[189]

Mars has the largest dust storms in the Solar System, reaching speeds of over 160 km/h (100 mph). These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase the global temperature.[190]

Wonder if this didn't help either preserving the Southern cap?:

In September 2017, NASA reported radiation levels on the surface of the planet Mars were temporarily doubled, and were associated with an aurora 25 times brighter than any observed earlier, due to a massive, and unexpected, solar storm in the middle of the month.

and:

Mars has the largest dust storms in the Solar System, reaching speeds of over 160 km/h (100 mph). These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase the global temperature.

The storms of 2012+2018 being significantly large to upset things I guess?

 

[Drifter]

On 06/10/2020 at 09:45, CraigT82 said:

Yes, as salty water had a very different relative permitivity (dielectric) to fresh water, which results in a different wave velocity

Bearing in mind how wobbly some of the subsurface radar trace results have been on some of these archaeological programmes (eg: Time Team surveys seemed to throw up features galore on trace maps …. but the Team mostly found little when they dug below the surface😆) Let's hope these instruments are more accurate!

Do you think there is any way that mild seismic activity on areas of Mars/ancient volcanic springs/ +geysers in the South could be slightly warming the liquid of these 3 subterranean lakes and changing the signature - maybe giving the impression it was brine?

…. With this area shrinking and sublimating rapidly, maybe Life Scientists need to be encouraged to rush to this area a bit quicker? - Be nice if these lakes were less salty - to increase the prospects there being a greater variety of microbes swimming around in them. 

Maybe around each extinct volcano there are lava tubes of condensed water containing more primitive life forms knocking out those pockets of Methane!?🧐 

No harm in speculating, throwing ideas around - just for fun … until manned missions/remote drone probes confirm one way or another.

Who knows - maybe those suspiciously dark plumes and spider staining of the sands around geysers in the South are a mixture of oozing ancient volcanic spring water through surface cracking/tectonics and primitive algaes clinging to survival as the liquid sublimates ...similar to those algaes on Earth??