Mercury's Spider Crater (APOD 04 Feb 2008)

copper5817 · Post by **copper5817** » Tue Feb 05, 2008 12:13 am

Yeah, I thought it looks like ridges instead of troughs too until I did what you guys suggested. Ridges almost make more sense like a crack in the surface that caused an eruption of some sort...but if they are not ridges then??? Missed it by THAT much...

craterchains · Post by **craterchains** » Tue Feb 05, 2008 1:00 am

Hi Bad Bouys,
You mentioned; "my mind is having a hard time assembling what must be a very steep and deep cliff down to the depression in the center, , , "

I have to admit that this is one very steep sided, and deep, crater for sure. It reminds me of a few on Iapetus (Saturn's system). The walls are quite oddly shaped as are a few of the other craters seen in that image. For an about 25 mile (40 km) wide crater it has very steep and deep walls. While it's ejecta blanket seems to be of dark material, the crater to the left of it in the Caloris basin has a much lighter ejecta blanket, some of which is seen in the left of this image. Remarkable that there are two different types of ejecta blankets in the same basin.

Norval

geonuc · Post by **geonuc** » Tue Feb 05, 2008 12:58 pm

Bruce D. Dod wrote:a "photo joint" perhaps, but terribly offset. Some of those "rays" will point to the crater better when realigned.

It's definitely a photo-joint, but I don't see it as being offset that much, particularly near the center of the image. Many of the troughs just do not point at the newer crater.

craterchains · Post by **craterchains** » Tue Feb 05, 2008 5:29 pm

The photo stitch is quite obvious, as is the 3/16 (180 mm) inch or so missing from the image along that line. it reminds me of this image, and what "they" don't want you to see or think about.

http://photojournal.jpl.nasa.gov/catalog/PIA02960

g-banjo · Post by **g-banjo** » Tue Feb 05, 2008 7:07 pm

Oh, oh!
NURSE!!

craterchains · Post by **craterchains** » Tue Feb 05, 2008 7:39 pm

oooooohhhh did ums give yerself a boo boo?

Get over it! , , , or slap a band aid on yer tactics, , , FOCLMFAO

g-banjo · Post by **g-banjo** » Wed Feb 06, 2008 2:19 am

??????

craterchains · Post by **craterchains** » Wed Feb 06, 2008 5:13 am

Well, you said,

Oh, oh!
NURSE!!

and I said,

oooooohhhh did ums give yerself a boo boo?

Get over it! , , , or slap a band aid on yer tactics, , , FOCLMFAO

I thought you hurt yourself and were asking for a nurse?

Bad Buoys · Post by **Bad Buoys** » Wed Feb 06, 2008 8:13 am

I don't blame him for being confused about your attack. I believe he was referencing your prior comment about the stitching operation.

Just goes to demonstrate how easily people can be misunderstood in this medium though nothing required your response other than your own mind.

I for one would like further insight to the crater. Did the meteor arrive from the upper right as there seems to be no cliff? Why does it appear the whole crater bottom collapsed leaving those cliffs in the back of the crater and also in the fore as evidenced by the shadow? And is the small black item at the center of the subsided crater the original entry hole or is it the meteor?

I'm aware you've looked at many craters and thus have intimate knowledge of their various forms and what they usually mean. Do you have any 'feel' for what transpired in that first second after impact here?

Curious, Doug

Andy Wade · Post by **Andy Wade** » Wed Feb 06, 2008 8:52 am

Bad Buoys wrote: I for one would like further insight to the crater. Did the meteor arrive from the upper right as there seems to be no cliff? Why does it appear the whole crater bottom collapsed leaving those cliffs in the back of the crater and also in the fore as evidenced by the shadow?

If you regularly visit LPOD ( http://www.lpod.org/ or currently here: http://the-moon.wikispaces.com/LPOD ) then the eminent Dr Chuck Wood regularly explains the process by which its craters have formed. On the moon there seem to be very few craters that are shaped by an oblique impact. Most are round in shape, which is something to do with the mechanics and the scale of the impact incident. Could the slope on the upper right quadrant just be slumped cliffs due to instability, other impacts or seismic activity?

Bad Buoys wrote:And is the small black item at the center of the subsided crater the original entry hole or is it the meteor?
Curious, Doug

Surely the small black item is a shadow cast by the central peak of the crater? Craters over a certain size usually have central peaks.
There would not be anything structurally left of any meteorite as they generally vapourise on impact.

BMAONE23 · Post by **BMAONE23** » Wed Feb 06, 2008 5:22 pm

Most of the other larger craters in the image appear to be similarly structured and lit which would indicate to me that there was no actual slumping but that the image was taken from the lower right looking toward the upper left of the area covered.

craterchains · Post by **craterchains** » Thu Feb 07, 2008 7:03 pm

The Caloris Basin on Mercury.

While researching CS types of crater chains for the past six years, CS means Concise and Systematic, FieryIce (Ms Gale Smart of BC Canada) and I have inadvertently become somewhat knowledgeable about craters and their formations. This included the study of just about every "paper" published by the researchers of note on the subject of craters and crater chains. We offer our thanks to them and others that have helped us to mold our understanding of our solar system and it's history of formation. Our stand that there has been a solar system wide war in the past one hundred and fifty years is also very well known by those that have taken the time to look up information about us. Spider Crater on Mercury shows many interesting and fascinating features that are of interest to us. Note the following pictures and information.

This image is a crop from the APOD image. To fully answer Doug's (Bad Buoys) question and curiosity of the following;

"I for one would like further insight to the crater. Did the meteor arrive from the upper right as there seems to be no cliff? Why does it appear the whole crater bottom collapsed leaving those cliffs in the back of the crater and also in the fore as evidenced by the shadow? And is the small black item at the center of the subsided crater the original entry hole or is it the meteor?

I'm aware you've looked at many craters and thus have intimate knowledge of their various forms and what they usually mean. Do you have any 'feel' for what transpired in that first second after impact here?"

First, besides the one stitch line found (1a), there is another here (1b).
Spider Crater formed after the so called "troughs" were formed as evidenced by the filling in of them near the crater by ejected material from the blast. Apparently some of these troughs were forming even as the ejecta was still falling back to the surface. We do give a very high probability that these troughs are in fact Concise and Systematic crater chains that have been eroded by shock waves from the blast when Spider Crater formed and other blasts vibrating the surface since then. Note that the crater that ejected some of it's lighter material onto Spider crater happened after Spider formed.

The following image is a crop from the best image found,

The cliff faces are abrupt possibly indicating some higher resistance to the blast effect. (1)
The slumping of wall material would indicate a softer material. (2)
Note the marks are after the settling of ejecta. (3)
The central peak is normal rebounding from the compression of the surface after the blast in this size and type of crater. (4) Or, it is a hardened material that resisted the blast.
And (5) is the stitch line of mating the photos.

Norval

g-banjo · Post by **g-banjo** » Thu Feb 07, 2008 9:08 pm

Ah. Right.

Bad Buoys · Post by **Bad Buoys** » Fri Feb 08, 2008 6:34 am

Thanks, that's what I was looking for.

I would think these steep cliffs would indicate a relatively 'fresh' crater. And I can understand that almost all impacts on Mercury would be close to the vertical as the rocks are accelerating toward the sun. Thanks to your crop, if we are looking down into the 'fresh' path of a missile, it appears to have entered from slightly to the upper right. In your experience, would that account for the wedge shape of the central "compression" wall?

But I still fail to understand how a crater can slump so uniformly to leave such cliffs. The only event on Earth, that I know of, which comes close is an underground atomic test. But if the meteor expired in a submercurian explosion; then that can't be an entry hole.

If it as fresh as you and the photo suggest do we have to wait for another flyby which won't give us much better resolution. Doesn't Hubble or one of its siblings have a looking glass which can focus that close?

emc · Post by **emc** » Fri Feb 08, 2008 2:59 pm

What is the slowest possible relative speed of a "loose" and natural solar system object?

g-banjo · Post by **g-banjo** » Fri Feb 08, 2008 3:01 pm

Forgive my igmorance. What's a "stitch line"?

FieryIce · Post by **FieryIce** » Fri Feb 08, 2008 3:08 pm

PhotoStitch - image stitching software, used to join multiple photographs together to produce a composite pictures such as panoramas.

See Norval's item 5 in the above photo.

iamlucky13 · Post by **iamlucky13** » Fri Feb 08, 2008 6:27 pm

emc wrote:What is the slowest possible relative speed of a "loose" and natural solar system object?

I assume you mean the slowest speed an object could strike Mercury with? That would be the same as it's surface escape velocity, which according to Wikipedia is 4.25 km/s or about 9500 mph. In reality, an impact would probably be significantly faster.

g-banjo · Post by **g-banjo** » Fri Feb 08, 2008 7:48 pm

Well of course "item 5" is a join - it is a composite picture - but I really don't see how, or why, you would suggest this about "1b".

emc · Post by **emc** » Fri Feb 08, 2008 7:55 pm

iamlucky13 wrote:
emc wrote:What is the slowest possible relative speed of a "loose" and natural solar system object?
I assume you mean the slowest speed an object could strike Mercury with? That would be the same as it's surface escape velocity, which according to Wikipedia is 4.25 km/s or about 9500 mph. In reality, an impact would probably be significantly faster.

Thanks for the answer! And yes, I was wondering if something very heavy (dense) hit Mercury at the subject impact zone at a relatively slow rate of speed... would it mosty "dent" Mercury's surface at the impact site and cause the conditions we see - if Mercury's surface was/is somewhat mushy, relatively speaking.

craterchains · Post by **craterchains** » Fri Feb 08, 2008 8:43 pm

Andy,
While Mercury may have the gravity to accelerate an object into it's surface, Phobos, a very small moon of Mars, would not. Yet Phobos does not show near miss craters of elongation. You asked, "Could the slope on the upper right quadrant just be slumped cliffs due to instability, other impacts or seismic activity?" As I mentioned, yes, the slumps are probably caused by subsequent explosions shaking the surface.

Bad Buoys,
My thinking is that this is an internal explosion brought about by the effects of the CS crater chain formations. Like the underground blasts done here on earth by atomic weapons where the blast blew the top off the containment area. It would also depend on the type of material surrounding what ever blew up.

What I wonder about the second "stitch" line in the photo, is why nobody else cought it?

g-banjo · Post by **g-banjo** » Fri Feb 08, 2008 9:04 pm

Ah, I've just googled "CS crater chains" and now see where you're coming from. A valuable reminder that we should make sure we help our children to understand the use of Occam's Razor.

entia non sunt multiplicanda praeter necessitatem

neufer · Post by **neufer** » Fri Feb 08, 2008 9:32 pm

craterchains wrote:Andy,
You asked, "Could the slope on the upper right quadrant just be slumped cliffs due to instability, other impacts or seismic activity?" As I mentioned, yes, the slumps are probably caused by subsequent explosions shaking the surface.

Norval,

Why are you so certain that the upper right quadrant has "slumped" ?

Perhaps the upper left quadrant looks steep mostly because it is facing the sun and MESSENGER has just crossed the plane of this crater wall; while the upper right quadrant looks shallow mostly because it is facing away from the sun and MESSENGER is more or less viewing it perpendicular to this crater wall. In your wide shot of these craters ALL of the larger craters appear to have a steep northwestern walls and a shallow northeastern walls (probably due to the perspective of the spacecraft).

geonuc · Post by **geonuc** » Sat Feb 09, 2008 11:59 am

g-banjo wrote:Well of course "item 5" is a join - it is a composite picture - but I really don't see how, or why, you would suggest this about "1b".

There is a linear feature at the left side of "1b", but it seems to die out towards the right. Either it is a natural (or alien war-caused) feature or a very good stitching job, unlike the upper one.

neufer · Post by **neufer** » Sat Feb 09, 2008 5:08 pm

orin stepanek wrote:http://apod.nasa.gov/apod/ap080204.html

Looks like a splash effect when it hit. Orin

http://antwrp.gsfc.nasa.gov/apod/ap020413.html

http://antwrp.gsfc.nasa.gov/apod/ap050925.html