Starship Asterisk*

by **bystander** » Tue Nov 25, 2008 9:51 pm

Ok, I guess I see it. The micro-cratering on the bottom left of the left pair through me for a while, but I bow to the consensus. Now, who do we ask for an explanation?

iamlucky13 wrote:Here's more information on the image. Unfortunately, it doesn't really help clarify it:
http://photojournal.jpl.nasa.gov/catalo ... r=pia11433

I've sent a request for clarification to photojournal@jpl.nasa.gov. Hopefully, they will respond.

by **Chris Peterson** » Tue Nov 25, 2008 9:39 pm

bystander wrote:I don't see any duplicate crater pairs, and the blurring appears to be blowing dust.

No, the two craters are definitely from the same data. There's a smaller crater to the left and above each that is the same as well. And much of the smooth surround has been copied, too. The two are very slightly different scales, so they haven't simply been cloned.

Hard to say what's going on. The image is completely synthesized from radar data; most likely, some section got duplicated in the model somehow.

by **Dave Jerrard** » Tue Nov 25, 2008 9:37 pm

bystander wrote:I don't see any duplicate crater pairs, and the blurring appears to be blowing dust.

Take a close look at these. A simple check is to tilt your head and cross your eyes so these craters overlap. Another check would be to load this into Photoshop and select one and place it over the other with a bit of transparency.

: glacialcraters-Duplicated-Illustrated.jpg (192.38 KiB) Viewed 1936 times

The left craters fade slightly on their left, and slightly above that area blurring is visible on the background. I do a lot of Photoshop work, creating, cloning and modifying textures and images (currently making high resolution maps of earth during the Cretaceous period), and when cloning areas with a feathered cloning brush, the feathered area tends to develop this same type of softening.

As I mentioned before, it's probably an attempt to cover up missing or corrupted detail in the original data.

He Who Had A Tough Time With Images On A Recent Hubble Show.

by **apodman** » Tue Nov 25, 2008 9:33 pm

The crater pair located above center right looks a lot like the crater pair located below center left.
Click on the image to see the full picture if the right side of the photo is chopped off.
This is cropped from the large image http://apod.nasa.gov/apod/image/0811/gl ... ro_big.jpg

by **bystander** » Tue Nov 25, 2008 9:18 pm

Dave Jerrard wrote:... If you look closely at the two crater pairs near the upper left of center of the image, you'll notice they are the same two craters - not similar, but exactly the same. Somewhere along the line, someone has modified the original image and cloned one crater pair (I suspect the craters on the right are the originals), probably to fill in some missing image data. The area behind the duplicate craters also seems to be blurred, which often occurs when cloning or retouching images. ...

I don't see any duplicate crater pairs, and the blurring appears to be blowing dust.

by **iamlucky13** » Tue Nov 25, 2008 9:15 pm

Dave Jerrard wrote:If you look closely at the two crater pairs near the upper left of center of the image, you'll notice they are the same two craters - not similar, but exactly the same.

Dave, I'm not sure I see the pair you're talking about. Is it the large pair near the horizon, each on what looks like a smooth plane?

I suspect it's an error fitting together a sequence of images taken of the surface from slightly different orientations onto an elevation model to produce the 3-D model used to produce this image. I've seen similar mistakes happen when stitching together panorama's from the Mars Exploration Rovers. It might also be that they didn't have imagery to use as a texture for part of the background, so for artistic purposes they copied part of the texture.

Here's more information on the image. Unfortunately, it doesn't really help clarify it:
http://photojournal.jpl.nasa.gov/catalo ... r=pia11433

And for those who wanted to see glaciers on Mars

by **Rocky Planet** » Tue Nov 25, 2008 9:04 pm

Dave Jerrard wrote:two crater pairs ... exactly the same

Good call. Now how about those JFK autopsy photos?

by **Dave Jerrard** » Tue Nov 25, 2008 8:17 pm

I've been a frequent visitor to the Astronomy Picture of The Day for several years now, going back to the late 90's. During that time, I've noticed a few images (entire pages, actually) get repeated on occasion. Today I noticed something else repeated, and it's in today's image.

It jumped out at me almost immediately. If you look closely at the two crater pairs near the upper left of center of the image, you'll notice they are the same two craters - not similar, but exactly the same. Somewhere along the line, someone has modified the original image and cloned one crater pair (I suspect the craters on the right are the originals), probably to fill in some missing image data. The area behind the duplicate craters also seems to be blurred, which often occurs when cloning or retouching images. I'm a visual effects artist, and I deal with these types of things quite frequently, and so they stand out quite readily to me. I just thought I'd bring this to your attention before certain 'experts' out there decide that another Martian civilization is being covered up.

He Who Has To Deal With Enough Nut Jobs Already.

by **neufer** » Tue Nov 25, 2008 1:31 pm

Dr. Skeptic wrote:http://antwrp.gsfc.nasa.gov/apod/ap050228.html
This APOD from 02/28/05 is where I would like to see a search for H2O.

Unusual looking craters! I wonder what the scale is.

by **Dr. Skeptic** » Tue Nov 25, 2008 12:36 pm

http://antwrp.gsfc.nasa.gov/apod/ap050228.html

This APOD from 02/28/05 is where I would like to see a search for H2O.

by **neufer** » Tue Nov 25, 2008 2:49 am

ta152h0 wrote:I would like to see NASA , on their next trip to land on MARS, to have a cup of water exposed to the martian environment and see what actually happens, and how fast. Maybe a shot glass full.

------------------------------------------
http://van.physics.uiuc.edu/qa/listing.php?id=1462

<<Liquid water will boil if its vapor pressure is greater than the ambient air pressure.

In a vacuum, liquid water will start to boil regardless of what the temperature is. Turning water from a liquid to a vapor takes 540 calories per gram, and this heat is taken from the liquid water, cooling it off. In a vacuum, the water will continue to boil until so much heat has been removed that the remaining water will freeze. This is a very quick way to freeze water.>>

http://www.youtube.com/watch?v=8oCjj8iDB9I
---------------------------------------
Surface pressure on Mars: 6 mmHg
Water vapor pressure at 39ºF : 6 mmHg

Hence, water above 39ºF will boil away until
the remaining water has cooled to below 39ºF

Then...

1) If Martian surface temperatures are above 39ºF
the remaining water will continue to boil away
(but somewhat more slowly).

2) If Martian surface temperatures are between
32ºF & 39ºF the remaining water will slowly evaporate.

3) If Martian surface temperatures are below 32ºF
the remaining water will slowly freeze.
................................................
<<Martian surface temperatures vary from
about −140 °C (−220 °F) during the polar winters
to highs of up to 20 °C (68 °F) in summers.>>
------------------------------------------

by **BMAONE23** » Tue Nov 25, 2008 12:04 am

Tilt wrote:Best I could do on short notice! <G>

Try a piece of dry ice
unless you meant it to be a Glassier

by **astrolabe** » Mon Nov 24, 2008 11:24 pm

Hello All,

This news is quite simply nothing short of marveloous!

by **NoelC** » Mon Nov 24, 2008 8:54 pm

Thanks for the clarification.

For what it's worth I've always believed there's water on that ball. There's simply too much of it around for the planet to be devoid of it.

-Noel

by **bystander** » Mon Nov 24, 2008 8:02 pm

NoelC wrote:My, my, aren't you being obstinate today.

Not unreasonable at all. I doubt NASA would claim water ice without good reason.

NoelC wrote:That's what's speculated. Don't they really have to go dig to find out for sure?

Probably more than speculation. The radar signature of any other type of ice would be different from that of water ice. Yes, to be sure, we will have to dig. Consider this, from the NASA news release:

Radar echoes received by the spacecraft indicated radio waves pass through the aprons and reflect off a deeper surface below without significant loss in strength. That is expected if the apron areas are composed of thick ice under a relatively thin covering. The radar does not detect reflections from the interior of these deposits as would occur if they contained significant rock debris. The apparent velocity of radio waves passing through the apron is consistent with a composition of water ice.

by **NoelC** » Mon Nov 24, 2008 7:53 pm

Water ice. It states this in the APOD caption and in the NASA news release.

My, my, aren't you being obstinate today.

That's what's speculated. Don't they really have to go dig to find out for sure?

Seems to me none of the stuff uncovered by NASA's most recent probe (RIP) turned out to be water ice.

-Noel

by **Tilt** » Mon Nov 24, 2008 7:40 pm

Best I could do on short notice! <G>

by **bystander** » Mon Nov 24, 2008 7:32 pm

Tilt, that would be water on mars, not glaciers, and there was an APOD on that, too.

APOD: 2005 April 1 - Water on Mars

by **Tilt** » Mon Nov 24, 2008 7:22 pm

Sorry ---- poor impulse control on my part! <WINK>

by **ta152h0** » Mon Nov 24, 2008 7:08 pm

NoelC wrote:Ah, but glaciers of what?

Does it have to be water?

The radar image does rather look as though something liquid has flowed there.

-Noel

A beer would be nice but i don't think a proposal like that would make it past the first stage.

by **bystander** » Mon Nov 24, 2008 6:40 pm

NoelC wrote:Ah, but glaciers of what?

Water ice. It states this in the APOD caption and in the NASA news release.

by **NoelC** » Mon Nov 24, 2008 6:11 pm

Ah, but glaciers of what?

Does it have to be water?

The radar image does rather look as though something liquid has flowed there.

-Noel

by **ta152h0** » Mon Nov 24, 2008 5:30 pm

I would like to see NASA , on their next trip to land on MARS, to have a cup of water exposed to the martian environment and see what actually happens, and how fast. Maybe a shot glass full.

by **bystander** » Mon Nov 24, 2008 2:59 pm

http://apod.nasa.gov/apod/ap081124.html

NASA spacecraft detects buried glaciers on Mars
Provided by Jet Propulsion Laboratory
Astronomy.com - 2008 Nov 21

NASA Mission News - MRO - 2008 Nov 20
Artist Concept of Glacier on Mars

Starship Asterisk*

Glaciers on Mars (2008 Nov 24)

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