APOD: Dry Ice Pits on Mars (2011 Sep 26)

[owlice]

Beyond, you need to click on more APOD links than you apparently do!

[Beyond]

I must have missed or forgotten about the boo bubbles when this APOD first came out. So when it came up this time, i didn't bother with the links, and therefore didn't make the connection correctly, to what you said. So i ended up giving myself a boo, without the bubble.
What is needed, is something to inject a steady supply of liquid soap, to be able to make bubbles non-stop.

[bystander]

... when this APOD first came out ...

This is the first time this image has appeared as an APOD. It was released by HiRISE on 2011 Sep 07.

[Beyond]

Ah, i thought it was an APOD, earlier. Now you can see what kind of a day I'm having. I need some sunny days to dry out from all the moisture around here this year. I'm beginning to feel a little like and it's starting to show

[rstevenson]

For those of you having trouble seeing these features as depressions, have a look at this sub-image I just made. I rotated it 90° CCW so the light comes from above, making it much easier for our minds to avoid the visual ambiguity. I also desaturated it to reduce the distracting golden glow, and then I cut the contrast and increased the brightness to show more detail in the shadow area.

Rob

[click it to see it larger]

[Beyond]

Gee, thanks Rob. Now i see it as if it's raised, like a frosted cookie sitting there. Well, back to the grey image i go.

Edit at 10:30. Now i see it as a depression. Plain as day.

[shaneh66]

I'm curious about the following sentence: "Around the South Pole of Mars, toward the end of every Martian summer, the warm weather causes a section of the vast carbon-dioxide ice cap to evaporate". Is it a scientific convention to refer to the season of an entire planet in terms of only its northern hemisphere? Should it not read, "...toward the end of the southern Martian winter...". As a resident of Earth's southern hemisphere, I'd hate to have to accuse anyone of being hemispherist".

[Ann]

shane66 wrote:

As a resident of Earth's southern hemisphere, I'd hate to have to accuse anyone of being hemispherist".

(But I see your point!)

Rob, thanks for the reversed image. It does make it easier to see those round things as depressions. Myself, I often have that problem when I'm looking at images of Mars that are taken from "above" (from an orbiting satellite): I don't know what is up or down!

But the picture sure is striking, even before you helped us see it, Rob.

Ann

[DavidLeodis]

It's a fascinating image. The pits look to me like some bracket fungus (apart from their gold colour) that grows on dead or decaying trees.

There's gold in them there pits!

[MartinL]

Well... as APOD's caption says: "These ice sheet pits may appear to be lined with gold, but the precise composition of the dust that highlights the pit walls actually remains unknown."

...

First of all go to politicians and actually TELL THEM THAT IT IS GOLD, we'll be on Mars in 3 years max.

Secondly - does anyone know how much gold would have to be on Mars so an expedition there would be economically reasonable?

Cheers,
M.

[Chris Peterson]

Secondly - does anyone know how much gold would have to be on Mars so an expedition there would be economically reasonable? :)

My guess is that the planet could be made of solid gold, and it wouldn't make any difference. That's because for the foreseeable future, the cost of transporting any given weight of gold from Mars to Earth will considerably exceed the value of that same weight.

Probably the most economically reasonable thing to transport is Martian dirt, which (for a while, anyway) would have a value on the collectors market far higher than gold or any common valuable metal.

[neufer]

does anyone know how much gold would have to be on Mars so an expedition there would be economically reasonable?

In 2003 Moon rocks were valued at about 250 times their weight in gold
so it would be cheaper to return to the moon and collect ordinary rocks.

[itisonlyme]

reproduce these images. They would be good for a floor tile pattern in a museum.

[mikef]

I love APOD, but have lurked for years. Something occurred to me when reading the commentary on this one, and I thought it was worth posting.
Having reviewed many different sources of data on humanity-induced climate change on Earth, I am a "believer." If somebody doubted this theory, however, and believes that changes in climate are soley a function of "natural cycles," then Mars might present a viable control planet for study. If climate changes are a function of changes by the sun, or by the solar system passing through regions of differing density ... then there should be similar evidence for this on Mars. Granted, weather patterns and soils are vastly different on Mars - but APOD has posted many photos showing that Mars is not an inert ball of rock without an active atmosphere. Therefore, ice and carbon analysis should be possible on sediment cores.
So, here is my message to politically conservative people who doubt that humans are responsible for climate change. Fund a series of Mars missions to compare a nearby planet without humans! If Mars' climate changes mirror Earth's climate changes, THEN we need an extra-strong economy to weather the upcoming warming cycle. Think of the Mars missions as an investment in your political ideals, or as a bet you can't lose since you're so sure of your ideals. If (on the other hand) there is no evidence of a parallel climate change on Mars (and science for Mars sediment analysis is viable), then we need to alter our behavior.

[bystander]

If you want to study a runaway greenhouse effect, go to Venus.

[NoelC]

The light is definitely coming from the left.

Your military left?

EDIT: Bah, no more than I was sure I took another look and now it's not so clear...

Looking over one of the very long strips, when I pan over to the mountains, where there's no snow, the light looks to be coming from the right, but I'll be darned if I can make my mind believe that the light is coming from the right when looking at these "pits".

-Noel

[neufer]

[size=175][color=#0000FF]The light [u][b]IS[/b][/u] definitely coming from the left[/color] :!: [/size]

---

The light is definitely coming from the left.

Your military left?

I stand by what I wrote. I've looked at this image every way imaginable, and in every case I'm convinced that these features have edges raised over the surrounding floor.

These are not pits but raised features.

[NoelC]

Heh, you turned the image around so I could be right - thanks.

I've been studying the shadows at the edges of these things for quite a while now (while waiting on hold on a phone call), and I haven't been able to find it possible to make my mind believe that these are pits.

For one thing, it's FAR easier to believe that the features inside the "pits" are bumps, surrounded by a smooth blanket of snow.

BUT...

I looked around one of the several hundred megabyte continuous images in this folder:
http://hirise-pds.lpl.arizona.edu/PDS/E ... 3464_0945/

I turned the image so it has the same light orientation as the APOD (180 degrees from neufer's message in the previous post), and if I panned over to where there is no snow the light looks to be coming from the right.

This is a strange, strange landscape indeed!

-Noel

[NoelC]

For example, if one forces oneself to think that the light is coming from the upper-right in this image, and further if we surmise that we're looking at a chasm with fairly steep walls, the silhouette of what appears to be a shadow on the chasm floor does seem to match the edge of the plain above...

However, in this very same image it's a bit difficult to explain how all the little features in the chasm floor could be holes in a surrounding smooth surface, but they would have to be for the light/shadow to look as it does.

-Noel

[neufer]

I've been studying the shadows at the edges of these things for quite a while now (while waiting on hold on a phone call), and I haven't been able to find it possible to make my mind believe that these are pits.

For one thing, it's FAR easier to believe that the features inside the "pits" are bumps, surrounded by a smooth blanket of snow.

If these were mesas rather than pits they would have been the first places to receive sunlight as the South Pole came out of polar night and, hence, would likely have been the first places to lose their snow cover. Since they are pits the snow cover was protected until later into the season.

[BMAONE23]

I love APOD, but have lurked for years. Something occurred to me when reading the commentary on this one, and I thought it was worth posting.
Having reviewed many different sources of data on humanity-induced climate change on Earth, I am a "believer." If somebody doubted this theory, however, and believes that changes in climate are soley a function of "natural cycles," then Mars might present a viable control planet for study. If climate changes are a function of changes by the sun, or by the solar system passing through regions of differing density ... then there should be similar evidence for this on Mars. Granted, weather patterns and soils are vastly different on Mars - but APOD has posted many photos showing that Mars is not an inert ball of rock without an active atmosphere. Therefore, ice and carbon analysis should be possible on sediment cores.
So, here is my message to politically conservative people who doubt that humans are responsible for climate change. Fund a series of Mars missions to compare a nearby planet without humans! If Mars' climate changes mirror Earth's climate changes, THEN we need an extra-strong economy to weather the upcoming warming cycle. Think of the Mars missions as an investment in your political ideals, or as a bet you can't lose since you're so sure of your ideals. If (on the other hand) there is no evidence of a parallel climate change on Mars (and science for Mars sediment analysis is viable), then we need to alter our behavior.

We don't see the same cyclical variations on Mars as we do on Earth, not because they don't exist but because the dynamics of the atmosphere is vastly different, and so the signatures are different.
Mars atmospheric Density = 0.020 kg/m3
= 0.0012 pounds/cubic ft
Earth atmospheric density = 1.23 kg/m3
= 0.0768 pounds/cubic ft
or 1.5% that of earth.
The martian atmospheric density isn't sufficient to support the same dynamics that reflect certain cyclical climate changes that are presant in the Earth climate signals.

Unfortunately, we haven't had operating climate stations there for more than the same duration as satellite measurements here. We haven't been there (or anywhere else) long enough to determine if the cycles are similar to earth or not.

[neufer]

So, here is my message to politically conservative people who doubt that humans are responsible for climate change.

The politically conservative people who really need convincing:

• 1) don't believe in science & don't trust scientists and
  2) don't care if polar bears starve or if folks in Bangladesh drown.

[Jasev]

APOD, I am amazed an astonished. Any amature astronomer can clearly see this photo shows sun from the lower left, and therefore clearly shows these are raised formations which have thawed on the raised, sun exposed edges. Notice the small one (bumps) which have not yet thawed, and also notice the dirction of the shadows from the small bumps on the hill tops (the so-called "pit floors"); if they where depressions, their shadows whould have to face the other direction (ie. if these are pits, the "authors" are claiming the sun is at the upper right corner). Also notice the remaining ice on the shadow side of the hills. The linked "pit" photo is indeed a thaw pit, this photo. however, is of a geological formation on Mars, which also has ice evaporation showing.

[BMAONE23]

So, here is my message to politically conservative people who doubt that humans are responsible for climate change.

The politically conservative people who really need convincing:

• 1) don't believe in science & don't trust scientists and
  2) don't care if polar bears starve or if folks in Bangladesh drown.

As to #2 polar bears are thriving and have grown to a population estimated to be 25,000 as of the last survey from an estimated population of 20,000 at the prior survey.

As to number 1
The scientific method states from WIKI

Scientific inquiry is generally intended to be as objective as possible, to reduce biased interpretations of results. Another basic expectation is to document, archive and share all data and methodology so they are available for careful scrutiny by other scientists, giving them the opportunity to verify results by attempting to reproduce them. This practice, called full disclosure, also allows statistical measures of the reliability of these data to be established.

In the case of climate science, the data has been viewed as intellectual property and hasn't been freely shared even when requests are made via the Freedom of Information Act.

If there were more openness then the debate might truly be settled but the techniques employed by Climate Scientists to avoid sharing data goes against the very methods they are supposed to stand for as scientists

[Chris Peterson]

APOD, I am amazed an astonished. Any amature astronomer can clearly see this photo shows sun from the lower left, and therefore clearly shows these are raised formations...

And just why is an "amature" (sic) astronomer able to make this observation?

Perhaps you don't realize that these structures have been imaged stereoscopically, seen under different lighting conditions, and been measured with radar? There is no doubt that they are depressions. In terms of understanding something like this, I wouldn't make any distinction between an amateur and a professional astronomer, but I'd make a distinction between a good and bad scientist- the former being one who use all the available data to see beyond a simple, well understood optical illusion.