APOD: The Spiral North Pole of Mars (2017 Dec 19)

[APOD Robot]

The Spiral North Pole of Mars

Explanation: Why is there a spiral around the North Pole of Mars? Each winter this pole develops a new outer layer about one meter thick composed of carbon dioxide frozen out of the thin Martian atmosphere. This fresh layer is deposited on a water-ice layer that exists year round. Strong winds blow down from above the cap's center and swirl due to the spin of the red planet -- contributing to Planum Boreum's spiral structure. The featured image is a perspective mosaic generated earlier this year from numerous images taken by ESA's Mars Express and elevations extracted from the laser altimeter aboard NASA's Mars Global Surveyor mission. New missions to Mars planned in the next few years include Insight with plans to drill into Mars, and ExoMars and the Mars 2020 Rover with plans to search for signs of microscopic Martian life -- past and present.

<< Previous APOD

This Day in APOD

Next APOD >>

[/b]

[Boomer12k]

Dry Ice to Chill the Champagne...a toast to Martian Xmas....Martian Santa getting ready no doubt...

:---[===] *

[heehaw]

Got to Florida yesterday: Mars looks real cold!

[MarkBour]

Dry Ice to Chill the Champagne...a toast to Martian Xmas....Martian Santa getting ready no doubt...
:---[===] *

Although spoken in jest, of course, it raises some interesting cultural questions for our possible future.

In 100 years, if we do have a good-sized settlement (or maybe even two) on Mars, will they tell their children that Santa is coming? Will Google Mars track his progress? If so, will it be based on a calendar from Earth? Would they (as you appear to suggest) invent their own Martian Santa? They probably won't show him following that spiral out of their North Pole ... in fact, if they stick with one Santa and one holiday, he might have to fly on a Musk-rocket to Mars and back. Hmmm ... but that would take too long (but it would nicely continue the commercialization of Christmas).

Clearly the first step we need to do before settling Mars is to set up a North Pole operation and get some elves out there in advance of civilizing the planet. Otherwise, it could turn out nearly as awful as this: http://www.imdb.com/title/tt0363240/

[De58te]

Just wondering, but is that pale blue dot visible just above the Martian horizon on the left hand side of this photo, the Planet Earth? And the nearby gray dot The Moon? And the other stars a little farther up, is one of them Venus and another Jupiter? Is this a picture showing a conjunction of planets? So many questions, so little time. Merry Christmas, Happy Hanukkah, Feliz Navidad , and Happy Atheism, every one.

[neufer]

<<The spiral troughs in the ice cap are formed by katabatic winds that entrain surface ice eroded from the equator-facing sides of the troughs, likely aided by solar ablation (sublimation), which is then redeposited on the colder pole-facing slopes. The troughs are roughly perpendicular to the wind direction, which is shifted by the Coriolis effect, leading to the spiral pattern. The troughs gradually migrate towards the pole over time; the central troughs have moved about 65 km in the last 2 million years. Chasma Boreale is a canyon-like feature older than the troughs, and in contrast is aligned parallel to the wind direction.>>

[b][color=#0000FF]Red Cliffs of Mars, at the Chasma Boreale. 2008 photo by HiRISE.[/color][/b]

---

<<Chasma Boreale is a large canyon in Mars's north polar ice cap in the Mare Boreum quadrangle of Mars at 83° north latitude and 47.1° west longitude. It is about 560 km long and was named after a classical albedo feature name. The canyon's sides reveal layered features within the ice cap that result from seasonal melting and deposition of ice, together with dust deposits from Martian dust storms. Information about the past climate of Mars may eventually be revealed in these layers, just as tree ring patterns and ice core data do on Earth. Both polar caps also display grooved features, probably caused by wind flow patterns. The grooves are also influenced by the amount of dust. The more dust, the darker the surface. The darker the surface, the more melting as dark surfaces absorb more energy.>>

[Catalina]

Does the water ice appear to be white also when the frozen carbon dioxide is not present?

[ESTRELLAFIN]

DOES THE CO2 FROST SUBLIMATE AND WHEN IT ENTERS THE ATMOSPHERE GET BLOWN AWAY BY THE SOLAR RIGHT? SO WHERE IS NEW CO2 COMING FROM...??

[neufer]

DOES THE CO2 FROST SUBLIMATE AND WHEN IT ENTERS THE ATMOSPHERE GET BLOWN AWAY BY THE SOLAR RIGHT?
SO WHERE IS NEW CO2 COMING FROM...??

• If Mars were ALL CAPS ALL THE TIME then ALL the atmospheric CO₂ might condense into dry ice.

<<The main component of the atmosphere of Mars is carbon dioxide (CO₂) at 95.9%. Each pole is in continual darkness during its hemisphere's winter, and the surface gets so cold that as much as 25% of the atmospheric CO₂ condenses at the polar caps into solid CO₂ ice (dry ice). When the pole is again exposed to sunlight during summer, the CO₂ ice sublimes back into the atmosphere. This process leads to a significant annual variation in the atmospheric pressure and atmospheric composition around the Martian poles.>>

[Guest]

I'm confused.

If the wind blows down from the North Pole, meaning towards the equator,and Mars rotates on its axis counterclockwise as seen from above the the North Pole, the spiral should unwind clockwise (Coriolis force), not counterclockwise as shown.

[neufer]

If the wind blows down from the North Pole, meaning towards the equator,and Mars rotates on its axis counterclockwise as seen from above the the North Pole, the spiral should unwind clockwise (Coriolis force), not counterclockwise as shown.

http://asterisk.apod.com/viewtopic.php? ... 9&#p278101