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Posted by: AlexBlackwell May 21 2007, 08:19 PM

http://www.jpl.nasa.gov/news/news.cfm?release=2007-061
NASA/JPL
May 21, 2007

Posted by: dvandorn May 21 2007, 09:01 PM

YES! I've been saying for a while that the entire Home Plate construct looks to me like remnants of a hot spring complex. Especially the way in which the layers within HP have been cemented and laid down -- it suggests (to me, anyway) deposition by mineral-rich water that has alternated back and forth from flowing to pooling.

I've known that several members of the Spirit team have favored the hot spring theory for some time. It's nice to see that they're hanging in there and finding evidence for their theory.

-the other Doug

Posted by: TheChemist May 22 2007, 12:40 PM

We've found the hiding place of Paso Robles

This might be bigger than it seems. I wonder what the implications will be for the interpretation of orbiter TES data now that there is ground-truth for amorphous silica.
Would the exploration of Columbia Hills have taken a different course if this discovery was made earlier ?

Posted by: ngunn May 22 2007, 05:15 PM

Are we to assume that this silica is in its anhydrous form or could it contain some water of crystallisation?

Posted by: imipak May 22 2007, 05:24 PM

Oh yes... they'd have dragged a wheel all the way from the top of Husband Hill to Home Plate

The silica finding's yet another convincing demonstration (as if all the other multi-coloured salt deposits weren't enough) of the usefulness of doing 'scuff' operations (as opposed to brushing/RAT) to see what's below the surface - *and* another example of the serendipity that only rovers can really deliver, IMHO. ("What do we want? Dozens more MERs! When do we want them? When budgetary constraints, DSN bandwidth and management resources permit!" )_chug!_( )

Posted by: Pavel May 22 2007, 08:07 PM

Actually, it's surprising that there is so little overlap between the rovers' discoveries. Other than olivine found by both rovers early into the mission, all other unusual materials or features were found by only one robot. Silica and salt are only in Gusev, blueberries are only in Meridiani. Volcanic bombs are in Gusev, festoons are in Meridiani. Layered bedrock is radically different, and even sand doesn't seem to be the same.
This means that more MERs are likely to discover more unique features if they are sent to new places on Mars. And even if they find something similar to Gusev or Meridiani, that would be exciting too.
MSL and Phoenix may be better equipped, but it's clear that it's not enough to cover unique places on Mars. MERs are proven, there are specialists with years of MER experience, and there is Mars-tested MER software.
I understand that NASA is supposed to innovate non-stop, but for the sake of science, sending more MERs would be the right thing to do IMHO.

Posted by: nprev May 22 2007, 08:54 PM

Maybe not. Hate to sound like a one-trick pony on this & other threads, but we're finally discovering that Mars is a lot more diverse than we thought, even if its environment pretty much ground to a halt in terms of types of changes other than dust storms a few By back.

Think that the similar appearances of the Viking & Pathfinder sites (plus, of course, our inability to go over the next hill & see what might be there on these missions) instilled a bit of a stereotypical outlook in many of us...it sure did in me. "Mars looks like this and the surface is composed of that"...is a vast overgeneralization just as it would be if said about the Earth.

More MERs and the infrastructure to support them? Hell, yes...I'd gladly decline my tax refunds for the next five years to get them there.

Posted by: Juramike May 22 2007, 09:24 PM

All these results shows the absolute genius in sending the same robust design to multiple locations.

Imagine if we took the same rover design (OK, tinker with it a tad based on what we've learned) and send it to more diverse locations. As they say in real estate: it's all about location, location, location. Heck, drop 'em down into the much more risky landing ellipses, even if only one survives, it will give us yet another view of Mars.

I also gotta believe rovers would be cheaper by the dozen.

Can we crank them out assembly line style? (Model T Mars Rover?)

(And I'll second nprev's comment: I'll forgo tax returns for 5 years for more Mars rovers, and I'd actually kick in extra bonus bucks for a Titan mission.)

-Mike

Posted by: djellison May 22 2007, 10:03 PM

Multiple MER's is a subject that's been done to death here and elsewhere. The bottom line is that while MER has been fantastic, the number of sites you can land with this system is very very small and very very limited and it's a highly inefficient way of getting a very small payload onto the ground. Because of that, MER's heritage should be in systems, not the entire vehicle.

If MSL works - you've got many orders of magnitude more Mars that can be accessed, and then it does make some sense to think about reusing MSL or indeed just its decent stage to deliver payloads.

Doug

Posted by: Pavel May 22 2007, 11:13 PM

I understand the RTG makes a significant part of the MSL mission cost, and it cannot be "reused", obviously. My uninformed guess is that RTG is one of the reasons why there will be only one MSL.
But you are right, it would be nice to reuse as much of MSL as possible if it succeeds.

Posted by: CosmicRocker May 23 2007, 05:08 AM

As much as I am drooling over the thought of MSL on Mars, I sure would feel better if there were two of them. I think there is some merit in the multi-MER concept. They are dynamite little explorers that have proven themselves and their EDL concept, but I think you run into a problem budgeting the large crew needed to keep many of them operating and exploring efficiently.

Getting back on topic...

That's an interesting question. If this silica is truly amorphous or non-crystalline, there can't be any water of crystallization. Besides, I am not aware of any crystalline form of silica that holds water. But opal is an amorphous form of silica that does contain variable amounts of water.

I don't know how they know that this silica is non-crystalline. Which instrument tells them that, or how do they infer it? I would suspect that if this material was not anhydrous, that fact would be widely advertised as further proof of water once on Mars. I think the mini-TES can see water wherever it may be.

Posted by: mchan May 23 2007, 08:16 AM

Reuse is meant to be reuse of the design by making additional copies of the original including the RTG. A copy mission could cost some fraction of the original mission cost.

Posted by: Oersted May 23 2007, 09:24 AM

Wouldn't it just mean some relatively minor modifications to the EDL system to make MER capable of landing in many more places? A bigger chute, larger retro-rockets? - The solar-powered concept is literally proving better and better for every day the rovers keep chugging on and making new discoveries.

Posted by: Cugel May 23 2007, 12:15 PM

As I understand it the MER EDL system can't be scaled up much more. You can't even launch an exact replica of MER on a Delta-2 anyway because of the poor Mars oppositions of the near future. So, you will need an Atlas or a Delta-4 which is 2x more expensive and offers a lot more payload... ergo you have a complete new mission. But I think/hope we will see some big solar powered rovers dangling on a skycrane EDL system in the future!

Posted by: Gray May 23 2007, 02:08 PM

What sort of chemical processes might cause silica to become so concentrated?

Posted by: ngunn May 23 2007, 02:23 PM

I'd love to know that too; I hope somebody can help us out.

My question about anhydrous or hydrated arose from the two related facts I do know - that anhydrous silica is a powerful dessicant but so is the Martian atmosphere. I just wondered which has the upper hand here.

Posted by: slinted May 23 2007, 10:13 PM

This was quite a shocker for me, since I'd been looking at the pictures of Gertrude Weise and thinking it was another exposed sulfate deposit. If it looks like sulfates, and gets disturbed like sulfates it must be... 90% silica!?
This does lend credence to the theory that the localized deposits are based on the composition of the underlying bedrock. Also, this would put the action of liquid water later in the relative timeline than any of the geologic evidence. After the underlying bedrock was formed it was exposed to liquid water, which concentrated the soluble elements close to the surface where the water would evaporate.

Expanding (and duplicating) on the images from the press release, here are some of the exposed bright patches Spirit has seen recently:

Sol 1187
http://www.lyle.org/~markoff/processed/2P231738423EFFATACP2533L234567M1.JPG

Sol 1194
http://www.lyle.org/~markoff/processed/2P232359891ESFATAZP2537L234567M1.JPG

Sol 1198, which shows two distinct units being exposed, the brighter/whiter on the left, and the blue/grey on the right
http://www.lyle.org/~markoff/processed/2P232714990EFFATB4P2539L234567M1.JPG

Posted by: tglotch May 24 2007, 12:40 AM

The Mini-TES is the instrument that determined that the silica is amorphous. The spectral character of amorphous or opaline silica looks quite different from quartz or one of the other crystalline polymorphs of SiO2.

As for water, the Mini-TES can qualitatively assess hydration state of soils by looking for a spectral feature near 6 microns. As far as I know (and I'm not positive), this white, silica-rich soil does not have a strong 6 micron feature, implying low or no water content in the silica.

Posted by: Stephen May 24 2007, 03:20 AM

True. But wouldn't an MSL also be a lot more expensive than an MER? With NASA already paring science and unmanned missions back to the bone in pursuit of the VSE it may not have the money to choose the Rolls-Royce of rovers over the Ford econovan version. Especially if scientists wanted to send more than one at the same time.

(In that context I notice that MEPAG in this document:

http://mepag.jpl.nasa.gov/reports/3715_Mars_Expl_Strat_GPO.pdf

tentatively advocates (for the 2016 opportunity) either "two MER-derived rovers" it terms "mid rovers" but only a single MSL-derived Astrobiology Field Rover.)

I also seem to remember the US currently have a plutonium shortage. Until that is addressed there will doubtless be a limit on how many MSL-style rovers can be despatched unless they were solar powered; and wouldn't a solar-powered MSL suffer from some of the same restrictions the solar-powered MERs have to put up with?

======
Stephen

Posted by: CosmicRocker May 24 2007, 04:16 AM

Thanks, Tim. In retrospect, I suppose I should have realized that. The mini-TES is quite a useful tool that often is neglected by enthusiasts. It has no nearly-real time equivalent to the raw jpeg images we get from the visual cameras, and its work is seldom illustrated in the news releases.

slinted: You're right. I think the initial, bright appearance fooled some of us into thinking it was the same old bright stuff. Now that we know better, check out the texture of that material. The large grain size is visible in the pancams, and that is quite different from the fine powder we've seen from the sulfates.

Posted by: David May 24 2007, 06:52 AM

Surely Spirit rather "Unmarses" this evidence?

("Digs up" would do just fine too.)

Posted by: dilo Jun 3 2007, 07:29 AM

New Sol1213 exposed bright patches (L257):

Posted by: Oersted Jun 6 2007, 02:48 PM

Spirit wants to sniff that more badly than a coke addict!