APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

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APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by APOD Robot » Wed Jul 20, 2016 4:07 am

Image Dark Dunes on Mars (Horizontally Compressed)

Explanation: How does wind affect sand on Mars? To help find out if it differs significantly from Earth, the robotic Curiosity rover on Mars was directed to investigate the dark Namib Dune in the Bagnold Dune Field in Gale Crater. Namib is the first active sand dune investigated up close outside of planet Earth. Wind-created ripples on Earth-bound sand dunes appear similar to ripples on Mars, with one exception. The larger peaks visible on dark Namib dune, averaging about 3 meters apart, are of a type seen only underwater on Earth. They appear to arise on Mars because of the way the thin Martian wind drags dark sand particles. The featured image was taken last December and is horizontally compressed to show context. In the distance, a normal dusty Martian landscape slopes up in light orange, while a rock-strewn landscape is visible on the far right. Curiosity unexpectedly went into safe mode in early July, but it was brought out last week and has now resumed exploring the once lake-filled interior of Gale Crater for further signs that it was once habitable by microbial life.

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Boomer12k » Wed Jul 20, 2016 5:00 am

Er...um.... when do you drill for microbial life?

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Ann » Wed Jul 20, 2016 5:56 am

Curiosity unexpectedly went into safe mode in early July, but it was brought out last week and has now resumed exploring the once lake-filled interior of Gale Crater for further signs that it was once habitable by microbial life.
Curiosity has resumed exploring the once lake-filled interior of Gale Crater for further signs that it was once habitable by microbial life?

What signs of microbial life has Curiosity found so far?

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by rj rl » Wed Jul 20, 2016 6:09 am

Beautiful blue skies deserved a mention :-)

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by geckzilla » Wed Jul 20, 2016 6:47 am

Pretty confusing image when it's squished.
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Guest » Wed Jul 20, 2016 7:03 am

Begs a couple of questions: Why is the sand of this dune field dark rather than red and why has that dark sand been concentrated in this dune field, rather than being dispersed, or mixed with red sand?

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by leonick » Wed Jul 20, 2016 7:50 am

Just a "curiosity": is it Phobos the bright spot visible in the sky?

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Case » Wed Jul 20, 2016 9:13 am

leonick wrote:Just a "curiosity": is it Phobos the bright spot visible in the sky?
I don't think so: it is a black spot in the raw image, so I think it became a white spot after image processing.
Also, Curiosity has been able to resolve Phobos using the same Mastcam to about 42 pixels wide, on Sol 351 (2013-08-01), when Phobos eclipsed Deimos.

That being said, Phobos should be at 11° above the horizon in the west (Az/Alt: 273°34'32"/+10°45'46"), shining at mag -7.40 (about between ISS flare and Iridium flare), with the Sun in north-east (Az 59°), at the time of this (sub)image (Sol 1192; Dec. 13, 2015,16:27:05 UTC). The shadows and the NASA caption tell that the images were taken with the camera looking roughly in the direction of the sun. The left side of the dunes is more lit, so the sun should be a bit left of this FOV, thus excluding the position of Phobos (which would be behind the camera).
Last edited by Case on Wed Jul 20, 2016 11:32 am, edited 1 time in total.

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Guest » Wed Jul 20, 2016 11:08 am

rj rl wrote:Beautiful blue skies deserved a mention :-)
Indeed... I was thinking the same.

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by JohnD » Wed Jul 20, 2016 11:11 am

As a criticism? I thought that the earlier Mars Rovers had shown that the Martian sky is pink?

The compressed image is ridiculous, bizarre and unhelpful, whereas the uncompressed panorama is impressive and informative.
Each to their own, at least we have both to see.

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by MadMan56 » Wed Jul 20, 2016 1:05 pm

Regarding the blue color of the sky, click on the "raw image" link in Case's post above. It is a monochrome image with color added.

I agree with the criticism of the horizontally compressed image, but I'm glad they mentioned that in the caption. I would show the image in natural proportions, cropping the ends if they don't want it to be too narrow.

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by rstevenson » Wed Jul 20, 2016 1:31 pm

Ann wrote:Curiosity has resumed exploring the once lake-filled interior of Gale Crater for further signs that it was once habitable by microbial life?

What signs of microbial life has Curiosity found so far?
Curiosity did not find signs of microbial life. But there's lots of evidence that conditions favourable to microbial life have existed on Mars in the distant past. That's all they're saying.

Rob

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Chris Peterson » Wed Jul 20, 2016 1:52 pm

MadMan56 wrote:Regarding the blue color of the sky, click on the "raw image" link in Case's post above. It is a monochrome image with color added.
No, it isn't. The images are made with a color sensor. The raw images haven't been de-bayered, so appear monochrome. But you can see the individual color filtered pixels. While the details of the color processing haven't been provided, the raw image itself contains color information.
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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Asterhole » Wed Jul 20, 2016 2:33 pm

Dark sand vis-à-vis the reddish color of the surrounding areas are due to their basaltic composition. Billions of Earth years ago when Mars was geologically (or is it areologically?) active, the materials for these dunes came spewing out of the numerous extinct volcanoes we are witness to today.

Along with this image being horizontally compressed, it is also color processed to resemble what it would look like under sunlight here on Earth. Hence the blue sky. In reality, it is pale pink.

And yes, no evidence of life found yet though some of the organic materials are present. Alas, all you dreamers but I fear all our exploration of this intriguing world will only show Mars is now and has always been lifeless.
They're all wasted!

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Cousin Ricky » Wed Jul 20, 2016 2:39 pm

Ann wrote:
Curiosity unexpectedly went into safe mode in early July, but it was brought out last week and has now resumed exploring the once lake-filled interior of Gale Crater for further signs that it was once habitable by microbial life.
Curiosity has resumed exploring the once lake-filled interior of Gale Crater for further signs that it was once habitable by microbial life?

What signs of microbial life has Curiosity found so far?
“Habitable,” not “inhabited.”

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Fred the Cat » Wed Jul 20, 2016 3:08 pm

geckzilla wrote:Pretty confusing image when it's squished.
Curiosity is "duning" an Escher. :ssmile:
Escher-Self-Portrait-1929.jpg
Which shares his hair! :mrgreen:
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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Ann » Wed Jul 20, 2016 7:31 pm

Cousin Ricky wrote:
Ann wrote:
Curiosity unexpectedly went into safe mode in early July, but it was brought out last week and has now resumed exploring the once lake-filled interior of Gale Crater for further signs that it was once habitable by microbial life.
Curiosity has resumed exploring the once lake-filled interior of Gale Crater for further signs that it was once habitable by microbial life?

What signs of microbial life has Curiosity found so far?
“Habitable,” not “inhabited.”
Oh. My mistake. Thanks.

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by neufer » Wed Jul 20, 2016 8:15 pm

Cousin Ricky wrote:
Ann wrote:
Curiosity unexpectedly went into safe mode in early July, but it was brought out last week and has now resumed exploring the once lake-filled interior of Gale Crater for further signs that it was once habitable by microbial life.
What signs of microbial life has Curiosity found so far?
“Habitable,” not “inhabited.”
Seems like it should have been "habitable FOR microbial life"
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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Ann » Wed Jul 20, 2016 8:38 pm

Fred the Cat wrote:
geckzilla wrote:Pretty confusing image when it's squished.
Curiosity is "duning" an Escher. :ssmile:

Escher-Self-Portrait-1929.jpg Which shares his hair! :mrgreen:
I like Escher's hair. He must have been the real Favorite Martian. Ray Walston must have been an impostor of some sort, with that Dune-less hair.

Or perhaps Escher was from Dune.

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Fred the Cat » Wed Jul 20, 2016 9:15 pm

Ann wrote:
I like Escher's hair. Or perhaps Escher was from...
I agree Ann. I'm "Martian green" with envy!
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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by Tom Malaby » Wed Jul 20, 2016 9:33 pm

Love the cat between the cushions (horizontally compressed link). Nice touch.

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by MarkBour » Wed Jul 20, 2016 10:47 pm

Asterhole wrote:Dark sand vis-à-vis the reddish color of the surrounding areas are due to their basaltic composition. Billions of Earth years ago when Mars was geologically (or is it areologically?) active, the materials for these dunes came spewing out of the numerous extinct volcanoes we are witness to today.
Hmmm. So this region is believed to have once been a lake. And the material in these dunes is believed to have come out of nearby volcanoes. Which happened first? The drying out of the lake, or the spewing out of the sand? Was this dark sand ever under the water?
Mark Goldfain

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by rstevenson » Wed Jul 20, 2016 10:56 pm

MarkBour wrote:
Asterhole wrote:Dark sand vis-à-vis the reddish color of the surrounding areas are due to their basaltic composition. Billions of Earth years ago when Mars was geologically (or is it areologically?) active, the materials for these dunes came spewing out of the numerous extinct volcanoes we are witness to today.
Hmmm. So this region is believed to have once been a lake. And the material in these dunes is believed to have come out of nearby volcanoes. Which happened first? The drying out of the lake, or the spewing out of the sand? Was this dark sand ever under the water?
I'm thinking it spewed out in a lava flow, not as sand, which then hardened into rock. Over the eons the rock was eroded down to its current sandy texture. I can't guess where the lake came in that sequence, though the water in the lake may have been part of the erosive process.

Rob

E vermore

Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by E vermore » Thu Jul 21, 2016 6:33 pm

geckzilla wrote:Pretty confusing image when it's squished.
Yup .. they could put a unaffected photo side by each. Too simple an idea I guess.

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Re: APOD: Dark Dunes on Mars (Horizontally... (2016 Jul 20)

Post by lola-yyc » Thu Jul 21, 2016 6:35 pm

May I ask, is that blue sky in the background of this image? Is that normal for Mars? I though our blue sky was the result of the wavelengths of light that can get through our atmosphere? Doesn't Mars have little or no atmosphere?