IPB

Welcome Guest ( Log In | Register )

14 Pages V  « < 7 8 9 10 11 > »   
Reply to this topicStart new topic
Cape York - The "Lakelands", Starting sol 2703
Matt Lenda
post Sep 20 2011, 08:40 PM
Post #121


Junior Member
**

Group: Members
Posts: 98
Joined: 17-July 11
From: Pasadena, CA
Member No.: 6066



QUOTE (MarkG @ Sep 19 2011, 10:42 AM) *
Is there enough control in the arm and enough brush left to sweep out the grind debris? I remember that the brush bristles were a bit "cattywumpus".

We are thinking about doing that sometime soon. There was considerable debate among the SOWG whether or not the extra rubbage in there would contaminate the exposed core of the rock. We've got ground in the loop to look at some things tomorrow and may try another brush+APXS.

Soonest we can count on boogeying on out of the Chesterlake area is... Friday? We'll be hitting nominal sols soon and it'll be day in day out for two weeks.

-m
Go to the top of the page
 
+Quote Post
Stu
post Sep 20 2011, 10:09 PM
Post #122


The Poet Dude
****

Group: Moderator
Posts: 5548
Joined: 15-March 04
From: Kendal, Cumbria, UK
Member No.: 60



QUOTE (Phil Stooke @ Sep 20 2011, 09:22 PM) *
Interesting responses! But that's why it would be interesting to collect RAT images throughout the mission to see how the holes have varied in appearance. Anyone? (I don't have time right now)

Phil


This page might be useful for you, Phil...

http://marswatch.astro.cornell.edu/pancam_...ges/merges.html


--------------------
Go to the top of the page
 
+Quote Post
Phil Stooke
post Sep 20 2011, 10:57 PM
Post #123


Senior Member
****

Group: Members
Posts: 5540
Joined: 5-April 05
From: Canada
Member No.: 227



... and even more useful for the person who makes the comparison image! Actually I think straight pancam images would be easier to use for this.

Phil



--------------------
... because the Solar System ain't gonna map itself.
Go to the top of the page
 
+Quote Post
Stu
post Sep 20 2011, 11:00 PM
Post #124


The Poet Dude
****

Group: Moderator
Posts: 5548
Joined: 15-March 04
From: Kendal, Cumbria, UK
Member No.: 60



Ok, just thought it was worth a look for you. I'll have a delve into the archives tomorrow.


--------------------
Go to the top of the page
 
+Quote Post
Phil Stooke
post Sep 21 2011, 12:12 AM
Post #125


Senior Member
****

Group: Members
Posts: 5540
Joined: 5-April 05
From: Canada
Member No.: 227



It's a great site, Stu! I just don't have time to look at this question right now - up to my ears in Itokawa problems.

Phil


--------------------
... because the Solar System ain't gonna map itself.
Go to the top of the page
 
+Quote Post
Bill Harris
post Sep 21 2011, 02:55 AM
Post #126


Senior Member
****

Group: Members
Posts: 2344
Joined: 30-October 04
Member No.: 105



QUOTE
considerable debate among the SOWG whether or not the extra rubbage in there would contaminate the exposed core of the rock
Brushing may not make a difference-- look at the surface of the pre-RAT IDD site and it looks really sand-blasted clean. Brushing off the cuttings would be critical if the surface were weathered or dust-covered. Though it would be nice to see what the clean, grinded surface looks like.

AFAIK, the next known important site is in the area of the CRISM phyllosilicate signature around that summit crater ~300m NE. And, of course, important sights seen along the way...

--Bill


--------------------
Go to the top of the page
 
+Quote Post
Jam Butty
post Sep 21 2011, 03:54 AM
Post #127


Junior Member
**

Group: Members
Posts: 51
Joined: 10-August 11
Member No.: 6119



A composite pancam/microscope image of the recent RAT hole in 'Chester Lake'
pancam L456 sol 2721
microscope sol 2719 (jvandriel's image from here)

Attached Image


Go to the top of the page
 
+Quote Post
CosmicRocker
post Sep 21 2011, 05:13 AM
Post #128


Senior Member
****

Group: Members
Posts: 2215
Joined: 1-December 04
From: Marble Falls, Texas, USA
Member No.: 116



QUOTE (Fran Ontanaya @ Sep 20 2011, 05:18 AM) *
Could they be obsidian in a perlite matrix?

That's certainly a possibility, Fran. I didn't think of that, but I suppose it could be obsidian in perlite. I don't have a lot of experience with volcanic glasses, but the few times I saw such rocks in the field, the obsidian inclusions were typically rounded and not angular like these. That's an interesting suggestion that I will have to consider. I have to wonder, though, would we expect to see glasses in rocks that are so old, or would they have devitrified after all this time, perhaps leading to the formation of clay minerals?


--------------------
...Tom
Go to the top of the page
 
+Quote Post
Bill Harris
post Sep 21 2011, 02:05 PM
Post #129


Senior Member
****

Group: Members
Posts: 2344
Joined: 30-October 04
Member No.: 105



I'm not familiar with that mineral, but AFAIK perlite is a volcanic glass (obsidian) that is hydrated and when heated, it expands producing a light weight, light-colored material. From the few pictures I've found it looks like a medium-greyish rock with a pearly luster. The diagnostic feature is that it expands greatly when heated.

What have we seen here that looks like perlite? And how was it identified? It would be good to find a perlite since that would imply an impact melt that was hydrated because it was created from a wet parent material.

Enquiring minds need to know...

--Bill


--------------------
Go to the top of the page
 
+Quote Post
tanjent
post Sep 21 2011, 04:53 PM
Post #130


Member
***

Group: Members
Posts: 123
Joined: 30-December 05
Member No.: 628



"Perlite" (I assume it's the same stuff) is a soil conditioner commonly used in hydroponic gardening. It's very soft - you can grind it between your fingers, and I think even under today's martian environmental conditions, exposed perlite would have long since eroded away from just the rarefied effects of the wind. I suppose there might be deposits of it buried underground dating from the noachian era, but very unlikely that it could be mined with just a RAT. (I'm no geologist - please let me know if this is a completely different substance I am thinking of.)
Go to the top of the page
 
+Quote Post
ngunn
post Sep 21 2011, 08:22 PM
Post #131


Senior Member
****

Group: Members
Posts: 3093
Joined: 4-November 05
From: North Wales
Member No.: 542



A break from mineralogy: the cyclops is crying.
http://qt.exploratorium.edu/mars/opportuni...19P2285L2M2.JPG
The crater seems to collect and 'focus' the downslope streak.
Go to the top of the page
 
+Quote Post
Phil Stooke
post Sep 21 2011, 09:19 PM
Post #132


Senior Member
****

Group: Members
Posts: 5540
Joined: 5-April 05
From: Canada
Member No.: 227



Great view!

Phil



--------------------
... because the Solar System ain't gonna map itself.
Go to the top of the page
 
+Quote Post
Bill Harris
post Sep 21 2011, 09:24 PM
Post #133


Senior Member
****

Group: Members
Posts: 2344
Joined: 30-October 04
Member No.: 105



Ah is a gee-ologist but 40 years outta school. "Perlite", as far as I can tell, is a manmade product created by heating a hydrated obsidian to some 1600*F where the volcanic glass softens and the entrained water causes it to"foam up" and expand. And as far as I can tell, hydrated obsidian, the mineral, is also (and possibly informally) called "perlite". I don't think that the manmade commercial soil additive occurs in natural deposits anywhere. However, I wonder if the "hydrated obsidian" could refer to an impact melt created from a water-saturated source material. With certain temperatures/pressures/timeframes I can see this as "possible".

Over time, a glass can weather or degrade from a "glassy" form to a "crystalline" form, a process called "devitrification". In obsidian samples, this is seen as "snowflake obsidian". It could devitrify into a smectite or a clay mineral, but I've seen no suggestions at Salisbury1 of devitrification of the impact melt.

And, picking nits, obsidian is a siliceous rhyolytic glass which is not compatible with the mafic (silica-poor) basalts we see in this region of Mars, so we're looking for glass of basaltic composition, such as a tachylite.

Why get worked up this much about a volcanic glass? It may well be the best way to do a comparative study of the creation and weathering of impact melt (impact glass) on Mars.

--Bill


--------------------
Go to the top of the page
 
+Quote Post
NickF
post Sep 22 2011, 01:52 AM
Post #134


Member
***

Group: Members
Posts: 105
Joined: 29-January 09
Member No.: 4589



Here's an L2/5/7 composite from sol 2718, part of the 'big pan'. There are some subtlety fascinating variations in colour coming through.

Attached Image




--------------------
Protein structures and Mars fun - http://www.flickr.com/photos/nick960/
Go to the top of the page
 
+Quote Post
CosmicRocker
post Sep 22 2011, 04:48 AM
Post #135


Senior Member
****

Group: Members
Posts: 2215
Joined: 1-December 04
From: Marble Falls, Texas, USA
Member No.: 116



QUOTE (Bill Harris @ Sep 21 2011, 03:24 PM) *
... Over time, a glass can weather or degrade from a "glassy" form to a "crystalline" form, a process called "devitrification". In obsidian samples, this is seen as "snowflake obsidian". It could devitrify into a smectite or a clay mineral, but I've seen no suggestions at Salisbury1 of devitrification of the impact melt. ...

At this point, even though it appears likely, we really don't know if we are seeing impact melts or not. But the point I was trying to make regarding devitrification was that after about 4 billion years any volcanic glass that may have existed should have had ample time to devitrify. Have you ever seen a Precambrian glass?

QUOTE (Bill Harris @ Sep 21 2011, 03:24 PM) *
... And, picking nits, obsidian is a siliceous rhyolytic glass which is not compatible with the mafic (silica-poor) basalts we see in this region of Mars, so we're looking for glass of basaltic composition, such as a tachylite. ...

I understand that we are expecting to see basaltic rocks here, but we don't "know" that all of the rocks here are mafic. Some silicic volcanics would probably be a very exciting discovery on Mars, but I was simply acknowledging Fran's observation that the current science target does resemble an outcrop of obsidian in a perlite matrix.

We have to remember that we are among the first geologists from our planet to have had the opportunity to explore the rocks of another. We should expect to be surprised as often as we find things that are familiar. smile.gif

N.B: The perlite used in hydroponics and soil conditioning may be derived from the rock known as perlite, but it is not the same thing.


--------------------
...Tom
Go to the top of the page
 
+Quote Post

14 Pages V  « < 7 8 9 10 11 > » 
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 25th July 2014 - 05:25 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.