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The major science stories from Spirit
elakdawalla
post Nov 24 2008, 09:23 PM
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I really, really, really tried to do my own research this time without relying on all you rover-watchers here for help, but after a couple of weeks of banging my head against a wall I'm coming crawling to you for help. I need to produce (for both our website and a podcast) a simplified, big-picture view of what Spirit has accomplished on Mars over the past five years. I've basically got to summarize five years of the mission in four minutes of speaking. The operational details (the main mileposts on the drive) are very easy to figure out with the help of Tesheiner's maps and the discussions in the route map thread, so I've got that in hand. What I am having trouble with is figuring out the answers to the following science questions:

1. What is the summary story that can be told about the history of the interior of Gusev crater based on Spirit's observations? Geology is fundamentally a science devoted to telling a story about a landscape -- what's the basic story that the Gusev landscape is telling us, as revealed by Spirit?

2. What are the biggest science discoveries -- I'm talking about the top three or five stories -- that Spirit has made?

There's just so much material on Spirit that I'm having an awful time trying to see the forest for all the trees. All the journal articles that I can find are just devoted to one phase of the mission, so I can't figure out which stories are the most significant. I have all of Salley's great articles to go through, but again, they're so detail-rich that it's difficult to figure out what the big picture is; it's like looking at a Seurat painting up close.

Any help or pointers to any place where anybody has already produced some quality science summary would be greatly appreciated.

--Emily


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Shaka
post Nov 25 2008, 02:33 AM
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Emily,
Two recent papers in JGR-Planets are helpful re the Spirit/Gusev status:
Arvidson et al. Spirit Mars Rover Mission to the Columbia Hills, Gusev Crater: Mission overview and selected results from the Cumberland Ridge to Home Plate.
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, E12S33, doi:10.1029/2008JE003183, 2008

Lewis et al. Structure and stratigraphy of Home Plate from the Spirit Mars Exploration Rover.
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, E12S36, doi:10.1029/2007JE003025, 2008

To quote from the first:
QUOTE
Evidence for extensive volcanic activity and aqueous alteration in the Inner Basin is also detailed, including discovery and characterization of accretionary lapilli and formation of sulfate, silica, and hematite-rich deposits.
...The evidence for aqueous alteration derived from Spirit’s data is associated with outcrops that are too small to be detected from orbital observations or withmaterials exposed from the shallow subsurface during rover activities. Although orbital observations show many other locations on Mars with evidence for minerals formed or altered in an aqueous environment, Spirit’s data imply that the older crust of Mars has been altered even more extensively than evident from orbital data. This result greatly increases the potential that the surface or shallow subsurface was once a habitable regime.

And from the second:
QUOTE
Our results are consistent with an explosive volcaniclastic origin for the layered sediments. Analysis of bedding orientations over half of the circumference of Home Plate reveals a radially inward dipping structure, consistent with deposition in the volcanic vent, or topographic draping of a preexisting depression. Detailed observations of the sedimentology show that grain sorting varies significantly between outcrops on the east and west sides. Observations on the western side show a well-sorted population of sand sized grains which comprise the bedrock, while the eastern margin shows a wider range of grain sizes, including some coarse granules. These observations are consistent with primary deposition by a pyroclastic surge. However, aeolian reworking of the upper stratigraphic unit is not ruled out.


Hope this helps


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elakdawalla
post Nov 25 2008, 02:42 AM
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That Arvidson et al. paper may not cover the whole mission but 1,000 sols is the biggest chunk I've seen covered in one paper -- most helpful, thanks, I hadn't seen it yet!

--Emily


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Astro0
post Nov 25 2008, 05:22 AM
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Emily, There are a lot of 'science' achievements from Spirit's mission, and to summarise these in just a few minutes will be a challenge.
I'm sure that people here will give you many thoughts and tips.

I have one thought about something you should include as an achievement aside from the science - smile.gif

"The success of operating a robot explorer on an alien world, in a harsh environment, climbing 'mountains', traversing a tough rocky terrain with (just to add to the fun) sandtraps, driving on five wheels for most of the mission (backwards!), with thickening dust on its solar panels and having to keep them oriented to the Sun, surviving freezing temperatures, major and minor dust storms, partially blinded eyes, ageing instruments, travelling many, many times further than designed to do, and communicating with biological entities on a distant planet who want you to do all this great science in what was to be a 90 Sol mission which is now going on five years."

The science is fantastic, the adventure is incredible!

However, as to the science, here are some references that might help you:
Four Years on Mars - http://www.jpl.nasa.gov/videos/mer/flightdirector-20080117/
Some nice images and comments from John Callas.

The Rover's science objectives:
http://marsrover.nasa.gov/science/objectives.html

Significant Discovery of Wetter Mars:
http://www.nasa.gov/mission_pages/mer/mer-20070521.html

Contributed paper to the IAU referenced here: (not sure if you can get the full paper - you may need to subscribe)
Abstract: Results of the Mars Exploration Rover mission to Mars are summarized
http://journals.cambridge.org/action/displ...act?aid=1431936

Cheers
Astro0
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Gsnorgathon
post Nov 25 2008, 06:12 AM
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In a way, one of Spirit's important discoveries was a non-discovery: if Gusev was a lake bottom, as seems obvious from orbital imagery, it was subsequently filled by floods of basalt. The early bits of Spirit's mission would have been terribly frustrating if not for the relief provided by Opportunity.
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ElkGroveDan
post Nov 25 2008, 07:29 AM
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If you are looking for specific events, I'd say the two huge discoveries were Pot o' Gold and Tyrone.


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climber
post Nov 25 2008, 09:45 AM
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In 4 minutes, I would take Astro's advise as a statment.
Then I'll speak of the 3 major phases (and discoveries):
+ the Plain = basalt = deception = we must move to the Hills
+ the Hills = first glimpse of water action (we went there to follow the water) + inspiring breathtaking views (first Mars mountain climber wink.gif )
+ Home Plate (the promise land) = "volcanism" (pure sand...)
...and the Exploration continue.
Good luck Emily smile.gif

Edit: I forget to speak about DD dd.gif and cleaning events. I know, I know, no relation between them but they are 2 major "discoveries", aren't they?


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djellison
post Nov 25 2008, 11:29 AM
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Best way I know to get the science story is two lectures Steve's done.

One particularly good science one is here
http://www.open2.net/sciencetechnologynatu...reslecture.html - in depth on the science half.

The other one, to bring it a bit more up to date, is here
http://uk.youtube.com/watch?v=vOv4LnAt01E
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mhoward
post Nov 25 2008, 06:13 PM
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This is a great topic. I'm making a new years' resolution to try to understand the science that's been done a bit more, starting with these links.
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dburt
post Nov 25 2008, 10:45 PM
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Emily,

I regret that this observation is not emphasized more by NASA or SS, but to me one of Spirit's most exciting discoveries was that everything off the landing plain appears to be layered and fragmental - coarse rock fragments with generally crude layering in the Columbia Hills, and fine salty sand with fine layering in Home Plate and vicinity. Except for what may be a single included ballistic rock fragment, the Home Plate layering greatly resembles that in Meridiani, especially the pervasive low angle cross beds (with some at higher angles). Other similarities include the underlying distinctive spherule-rich bed (reportedly with crystalline hematite), and the ferric acid sulfates, locally even richer at Gusev (up to 40%) than at Meridiani (up to 30%). Despite these obvious similarities, two completely different (but fundamentally Earth-like) causes have been inferred for the two sets of layered rocks, sulfate minerals, and spherules- volcanic (pyroclastic) surge from a vanished or hidden volcano (with vanished fumaroles and accretionary lapilli) for one, and an exceedingly complex set of events involving salt evaporation from vanished or hidden muddy acid playa lakes, silicate/salt transport and deposition by the wind, and alteration and redeposition by standing and flowing acid liquid water for the other.

A fragmental silica-rich bed, stratigraphically between the spherule-rich bed and the beds of Home Plate proper, so far appears to be unique to Gusev, and therefore probably ranks as Spirit's single most interesting discovery.

-- HDP Don
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SpaceListener
post Nov 26 2008, 12:20 AM
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The close pictures on dust devil are the plus and unique of mission of Spirit. During the summer time, when Spirit was at the top of Hill Columbia, took an original activity: Astronomy taking some sky pictures when she had plenty of energy reserve to disipel. The other important Spirit's discovery was when she was heading toward Home Plate, trying to overcome a slope, her wheels have scratched the surface and found lots of sulfate....Indication of wathering of surface.

Finally, Spirit took lots of time on the highest point of Columbia hill taking the most complete picture around the Gusev!!!

And much more from others who can recall her stories...
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elakdawalla
post Nov 28 2008, 05:24 PM
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Thanks for all these replies, guys. My Internet access has been limited over the holiday but I'm reading everything and plan to get some writing done early next week. It's possible I may get a chance to ask SS what he thinks the biggest science stories are -- I'm glad for those Arvidson et al papers, which I printed out for some holiday reading -- they're giving me a good review! SS wrote a companion Oppy one to the 2006 paper, but there doesn't seem to be one in press yet for 2008, which would cover the subsequent 1,000 sols. I wonder if he has a draft in preparation...

--Emily


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Doc
post Nov 28 2008, 05:49 PM
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QUOTE (dburt @ Nov 26 2008, 01:45 AM) *
Emily,

A fragmental silica-rich bed, stratigraphically between the spherule-rich bed and the beds of Home Plate proper, so far appears to be unique to Gusev, and therefore probably ranks as Spirit's single most interesting discovery.

-- HDP Don


Thank you, I was wondering when someone was going to say that! rolleyes.gif


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Juramike
post Jan 9 2009, 10:56 PM
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I thought this was pretty cool: http://www.space.com/scienceastronomy/090109-mars-rocks.html

I'd been wondering why the rock spacing on Mars looked like it was kinda plopped around rather than all bunched together. This article explains tries to explain why.

If the wind is undercutting the sand under the rocks as deflation proceeds, it could pitch each rock slowly forward over the eons and space them apart.

Neat explanation.

-Mike


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brellis
post Jan 9 2009, 11:14 PM
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QUOTE (Juramike @ Jan 9 2009, 02:56 PM) *
If the wind is undercutting the sand under the rocks as deflation proceeds, it could pitch each rock slowly forward over the eons and space them apart.

-Mike


Perhaps Mars is expanding. rolleyes.gif
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