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Possible recent lunar volcanism
Bjorn Jonsson
post Oct 13 2014, 09:23 PM
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This is very interesting - and unexpected (at least to me):

http://lroc.sese.asu.edu/posts/818

Apparently there may be small features of volcanic origin on the Moon that are less than 100 million years old. The images are also very interesting - I would probably never have guessed that the image at the top was of lunar terrain.


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nprev
post Oct 13 2014, 09:45 PM
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I see gross similarities with some purported Mercurian volcanic features. Interesting indeed!


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Phil Stooke
post Oct 13 2014, 10:44 PM
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You saw it here first:

http://www.unmannedspaceflight.com/index.p...6070&st=375


(and many other posts in that thread if you follow it)

Sarah Braden was already well into documenting the features, I think, but had not published anything, when I did an LPSC poster on them.


Phil


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wildespace
post Oct 20 2018, 10:44 AM
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Ah, glad I found this thread, as I've just come across the "Ina" feature.

In an Apollo image of the area, it could be seen that the floor of Ina has a bluish tinge. Anyone know an explanation for this? What kind of minerals are giving it bluish hue?

AS17-152-23287 (auto-colour balanced from an unprocessed Flickr image)

Attached Image


Neal Spence combined the Apollo photo with high-rez b&w image from LRO (M175246029L).

Attached Image


Flickr: http://www.flickr.com/photos/terraform-mars/43614947480
Gigapan: http://www.gigapan.com/gigapans/211918


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Phil Stooke
post Oct 20 2018, 05:53 PM
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First, let me assure you there are no blue minerals here. The blue is not a true representation of the nature of the surface.

In general on atmosphereless bodies, freshly exposed material is brighter and 'bluer' (reflecting slightly more light from the blue end of the visible spectrum) and old material exposed to the space environment for a long time is darker and a bit redder. If you were there, looking at it, it would mostly look neutral but you might see a bit more red or brown in the darker areas and less red in the brighter areas.

Here we have a photo taken on film 40 years ago. We don't really know how well the film reproduced the actual color, or how it has changed in storage. It has been scanned - but is this a scan from the original negative or from a later print or negative? The scanner might not give a perfect reproduction of the source. Most important of all, the color balance process deliberately shifts the spectrum, and this is probably the most important source of a false blue tint.

Ina has a bright floor which has been exposed relatively recently in lunar terms - its floor might be 100 million years old, the dark regolith surface around it is much older and is space weathered - made darker and redder. The bright stuff is really fairly neutral in tone. Color balancing makes it look blue, but it is not.

Phil


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monty python
post Oct 21 2018, 05:46 AM
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It's kinda weird still. Are the light areas depressions or high areas, and how was it made?
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wildespace
post Oct 22 2018, 03:19 PM
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QUOTE (monty python @ Oct 21 2018, 06:46 AM) *
It's kinda weird still. Are the light areas depressions or high areas, and how was it made?

The brighter area is a depression, and darker areas are elevated. It can be really difficult getting your head around it.

BTW, here's an unprocessed scan of AS17-152-23287: http://www.flickr.com/photos/projectapollo...57659004120278/
This source mentions that the bluish colouration of Ina's floor is due to titanium-rich minerals: http://apollo.mem-tek.com/Ina/Ina.html
These document also confirm bluish tint as noted by Apollo astronauts, due to titanium-rich minerals:
http://apollo.mem-tek.com/Ina/PDF/1980-10%...%20-%201980.pdf
http://apollo.mem-tek.com/Ina/PDF/2011-10%...%20-%202499.pdf


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John Moore
post Oct 22 2018, 05:18 PM
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As to how Ina was made, and indeed other IMPs (Irregular Mare Patches - volcanic in nature) the most recent hypothesis suggests that the depression units are a left-over crust from a much larger lava lake
magma that developed deep down below within a dike/vent environment.

Essentially, the magmas produced a crust metres-thick composition in where numerous cracks formed during its cooling period, and that magmatic foamy deposits below (a mixture of magma with gases
created in the lava lake) squeezed through these cracks, producing the darker-looking, bulbous 'mounds' (as they are usually referred to) in the floor.

There are several other hypotheses as to IMP formation mechanisms. Surface features like craters, degradation and erosion effects, wall and mound slopes, regolith thickness, their surrounding mares etc.,
etc,. all have to be considered, too - each supporting the research posed in each hypothesis.

But the most important aspect about IMPs is the approximate age of them; where some hypotheses suggest that IMPs are young by millions of years, others suggest that they formed billions of years ago and
fit in with the generally-accepted theory that volcanism ended on the Moon round then. The age issue is very controversial today - because if they are young, then volcanism on the Moon ended later than
expected, and so thermal and magmatic models would have to be seriously revised.

A SmallSat concept mission, called IMPEL (Irregular Mare Patch Exploration Lander), could answer the question in the near future, particularly for Ina at which would be its intended target.

The various images out there of all IMPs proposed can be confusing - some views show them' flipped' or 'reversed' due to natural original images recorded by the Lunar Reconnaissance Orbiter (LRO) in its
orbit, some repeat odd-wise in a combination of both.

The forth-coming book, in early 2019, should set the record straight. All of the 70 so-far catalogued IMPs (with high-rez LROC images and lat/long coordinates) to date are included, as well as 35 additional
uncatalogued IMP features. LRO NAC numbers/references are also included with all, while a brief description on each and how to access them easily is included.

IMPs are an oddity...time to explore them more.

John Moore
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