by bystander » Sun Nov 16, 2014 1:57 am
Candy Hansen wrote:Spring in Inca City I (ESP_037626_0985) (HiClip)
Every winter a layer of carbon dioxide ice—or, dry ice—condenses in the Southern polar region, forming a seasonal polar cap less than 1 meter deep. Early in the spring the ice layer begins to sublimate (going directly from a solid to gas) from the top and bottom of the ice layer. Under the ice gas pressure builds up until a weak spot in the ice layer ruptures. The gas rushes out and as it escapes it erodes a bit of the surface.
Fine particles are carried by the gas to the top of the ice and then fall out in fan-shaped deposits. The direction of the fan shows the direction either of the wind or down the slope. If the wind is not blowing a dark blotch settles around the spot the gas escaped.
This region is known informally as Inca City, and
it has a series of distinctive ridges. On the floor between the ridges are radially organized channels, known colloquially as spiders, more formally called "araneiforms." The channels have been carved in the surface over many years by the escaping pressurized gas. Every spring they widen just a bit.
This was the first image to be acquired after the sun rose on Inca City, marking the end to polar night. A few fans are visible emerging from the araneiforms.
Candy Hansen wrote:Spring in Inca City II (ESP_037811_0985) (HiClip)
It is about two weeks later in Inca City and the season is officially spring. Numerous changes have occurred. Large blotches of dust cover the araneiforms. Dark spots on the ridge show places where the seasonal polar ice cap has ruptured, releasing gas and fine material from the surface below.
At the bottom of the image fans point in more than one direction from a single source, showing that the wind has changed direction while gas and dust were flowing out. Was the flow continuous or has the vent opened and closed?
Candy Hansen wrote:Spring in Inca City III (ESP_037877_0985) (HiClip)
In Inca City another week has passed, and
there are a few more fans on the ridge. We are studying the sequence of spring activity with the help of citizen scientists at the
Planetfour website, sponsored by
Zooniverse.
Citizens of planet Earth log on and identify and measure fans and blotches in the South polar region of Mars imaged by HiRISE. With their help we can study the polar weather by looking at how the fan directions change through the spring.
We see how the number of fans and blotches depends on the thickness of the ice layer and how high the sun is in the sky. If you would like to be a part of this endeavor join us at
www.planetfour.org.
Candy Hansen wrote:Spring in Inca City IV (ESP_038022_0985) (HiClip)
At certain times in spring, fans
take on a gray or blue appearance. This is the time in Inca City when this phenomenon happens.
On the ridge at the top of the image fans have lengthened and now look more gray than the blotches on the araneiforms. At the bottom of the image they are distinctly blue in color.
Two theories have been suggested: perhaps fine particles sink into the seasonal layer of ice so they no longer appear dark. Or, maybe the gas that is released from under the ice condenses and falls to the surface as a bright fresh layer of frost. It is quite likely that both of these theories are correct.
Candy Hansen wrote:Spring in Inca City V (ESP_038299_0985) (HiClip)
A significant event has occurred in Inca City. The layer of seasonal ice
has started to develop long cracks. This is visible in the orange-colored band adjacent to the araneiforms. Fans of dust are emerging from long linear cracks. The cracks form when large plates of ice have no easily ruptured weak spots to release the pressure from gas building up underneath, so the ice simply cracks.
There are also more fans on the ridge at the top of the image, and more have appeared in between the araneiforms. We do not have any analogous processes occurring naturally on Earth: this is truly Martian.
Credit: NASA/JPL/University of Arizona
<< Previous HiRISE Update[quote="Candy Hansen"][float=left][img3=""]http://www.uahirise.org/images/wallpaper/800/ESP_037626_0985.jpg[/img3][/float][size=110][b][i][url=http://www.uahirise.org/ESP_037626_0985]Spring in Inca City I (ESP_037626_0985)[/url] ([url=https://www.youtube.com/watch?v=8ZeiTYaIHsU]HiClip[/url])[/i][/b][/size]
Every winter a layer of carbon dioxide ice—or, dry ice—condenses in the Southern polar region, forming a seasonal polar cap less than 1 meter deep. Early in the spring the ice layer begins to sublimate (going directly from a solid to gas) from the top and bottom of the ice layer. Under the ice gas pressure builds up until a weak spot in the ice layer ruptures. The gas rushes out and as it escapes it erodes a bit of the surface.
Fine particles are carried by the gas to the top of the ice and then fall out in fan-shaped deposits. The direction of the fan shows the direction either of the wind or down the slope. If the wind is not blowing a dark blotch settles around the spot the gas escaped.
This region is known informally as Inca City, and [url=http://static.uahirise.org/images/2014/details/cut/ESP_037626_0985.jpg][b]it has a series of distinctive ridges[/b][/url]. On the floor between the ridges are radially organized channels, known colloquially as spiders, more formally called "araneiforms." The channels have been carved in the surface over many years by the escaping pressurized gas. Every spring they widen just a bit.
This was the first image to be acquired after the sun rose on Inca City, marking the end to polar night. A few fans are visible emerging from the araneiforms. [/quote]
[quote="Candy Hansen"][float=left][img3=""]http://www.uahirise.org/images/wallpaper/800/ESP_037811_0985.jpg[/img3][/float][size=110][b][i][url=http://www.uahirise.org/ESP_037811_0985]Spring in Inca City II (ESP_037811_0985)[/url] ([url=https://www.youtube.com/watch?v=W-HSkL2E-R4]HiClip[/url])[/i][/b][/size]
It is about two weeks later in Inca City and the season is officially spring. Numerous changes have occurred. Large blotches of dust cover the araneiforms. Dark spots on the ridge show places where the seasonal polar ice cap has ruptured, releasing gas and fine material from the surface below.
[url=http://static.uahirise.org/images/2014/details/cut/ESP_037811_0985.jpg][b]At the bottom of the image[/b][/url] fans point in more than one direction from a single source, showing that the wind has changed direction while gas and dust were flowing out. Was the flow continuous or has the vent opened and closed? [/quote]
[quote="Candy Hansen"][float=left][img3=""]http://www.uahirise.org/images/wallpaper/800/ESP_037877_0985.jpg[/img3][/float][size=110][b][i][url=http://www.uahirise.org/ESP_037877_0985]Spring in Inca City III (ESP_037877_0985)[/url] ([url=https://www.youtube.com/watch?v=-QEayhnVo0M]HiClip[/url])[/i][/b][/size]
In Inca City another week has passed, and [url=http://static.uahirise.org/images/2014/details/cut/ESP_037877_0985.jpg][b]there are a few more fans on the ridge[/b][/url]. We are studying the sequence of spring activity with the help of citizen scientists at the [url=http://www.planetfour.org/][b]Planetfour website[/b][/url], sponsored by [url=https://www.zooniverse.org/][b]Zooniverse[/b][/url].
Citizens of planet Earth log on and identify and measure fans and blotches in the South polar region of Mars imaged by HiRISE. With their help we can study the polar weather by looking at how the fan directions change through the spring.
We see how the number of fans and blotches depends on the thickness of the ice layer and how high the sun is in the sky. If you would like to be a part of this endeavor join us at [url=http://www.planetfour.org/][b]www.planetfour.org[/b][/url]. [/quote]
[quote="Candy Hansen"][float=left][img3=""]http://www.uahirise.org/images/wallpaper/800/ESP_038022_0985.jpg[/img3][/float][size=110][b][i][url=http://www.uahirise.org/ESP_038022_0985]Spring in Inca City IV (ESP_038022_0985)[/url] ([url=https://www.youtube.com/watch?v=s5kdVEfWoHY]HiClip[/url])[/i][/b][/size]
At certain times in spring, fans [url=http://static.uahirise.org/images/2014/details/cut/ESP_038022_0985.jpg][b]take on a gray or blue appearance[/b][/url]. This is the time in Inca City when this phenomenon happens.
On the ridge at the top of the image fans have lengthened and now look more gray than the blotches on the araneiforms. At the bottom of the image they are distinctly blue in color.
Two theories have been suggested: perhaps fine particles sink into the seasonal layer of ice so they no longer appear dark. Or, maybe the gas that is released from under the ice condenses and falls to the surface as a bright fresh layer of frost. It is quite likely that both of these theories are correct. [/quote]
[quote="Candy Hansen"][float=left][img3=""]http://www.uahirise.org/images/wallpaper/800/ESP_038299_0985.jpg[/img3][/float][size=110][b][i][url=http://www.uahirise.org/ESP_038299_0985]Spring in Inca City V (ESP_038299_0985)[/url] ([url=https://www.youtube.com/watch?v=KrISNdPNAQM]HiClip[/url])[/i][/b][/size]
A significant event has occurred in Inca City. The layer of seasonal ice [url=http://static.uahirise.org/images/2014/details/cut/ESP_038299_0985.jpg][b]has started to develop long cracks[/b][/url]. This is visible in the orange-colored band adjacent to the araneiforms. Fans of dust are emerging from long linear cracks. The cracks form when large plates of ice have no easily ruptured weak spots to release the pressure from gas building up underneath, so the ice simply cracks.
There are also more fans on the ridge at the top of the image, and more have appeared in between the araneiforms. We do not have any analogous processes occurring naturally on Earth: this is truly Martian. [/quote]
[b][i]Credit: NASA/JPL/University of Arizona[/i][/b]
[url=http://asterisk.apod.com/viewtopic.php?t=34047][size=85][b][i]<< Previous HiRISE Update[/i][/b][/size][/url]