Jim Bell Q'n'a, Questions Please Options

[The Messenger]

Jim -

About a year ago, Oppy, spent a couple of days checking out her tattered heat shield...(It actually popped inside-out on landing.) Any feedback on the assessment? Did Oppy come in hot or cold?

[Bob Shaw]

Look at the vertically-exaggerated image posted here.

Home Plate seems very obviously, in this stretched image, to be the remnant of an impact crater.  There are several impact crater remnants in the inner basin, here.  Each seems to have been formed in a surface that was a good many meters higher than the present surface -- those missing several meters have been deflated from this terrain, by some process, leaving the shocked "pedestal" remnants of the deeper cratering forms.

Remember, when you make an impact crater, you don't just affect the surface.  The disruption caused by the cratering event goes well under the surface, consisting of impact melt (if the impact is energetic enough) and shocked, brecciated rocks.

The crater remnants we're seeing on the surface look like the brecciated and shocked rocks that were originally created in a bowl-shaped lining beneath this cluster of impact craters.  I can see traces of at least five different craters within the inner basin, here.  (The ridge of rock Spirit is passing right now is, in fact, a small crater remnant.)

As for Home Plate, it sits within the largest and most well-defined of these crater remnants.  Maybe such layers were exhumed in *all* of the craters here, and have since been completely eroded away -- but that doesn't seem right.  We have traces of several craters, and in only one of them do we see any trace of this lighter-colored material.

I'd have to think that either the impact target composition was different where the Home Plate impact occurred -- which seems a little unlikely when you consider some of these impacts are only a few tens of meters apart -- or that some other substance was deposited in Home Plate crater that wasn't deposited in the other craters.  (Or that has been completely deflated from the other craters, if it ever existed there.)

So, logic *seems* to point towards post-cratering material deposition accounting for the light-rock ring.  Personally, I think it could have been water deposition.  Home Plate could have been a puddle that was filled and dried thousands of times (maybe with an internal artesian spring) that resulted in aqueous transport and deposition.

Or, it could have just been a good wind trap and it trapped a lot of light-colored dust.  Hard to say.

I'm not only interested in the light-rock ring's composition, I'm getting very curious about the erosion process that deflated the original surface.  Could aeolian erosion have deflated *that* much surface, even over a few billion years?  Do we need to postulate aqueous erosion, or even glacial erosion?

Maybe the specific composition and erosion patterns we see on the light-rock ring will help us puzzle that out.

-the other Doug

otherDoug:

I lean towards your interpretation in all regards, but confess that caution is whispering a big 'wait and see' in my ear - it could be simply an isolated and exposed unit of a more pervasive structure (as indicated by other, similar local landforms). However, I 'want' it to be some sort of exhumed crater, replete with shock cones, oh yes, I do! I sincerely hope that there'll be enough time for Spirit to thoroughly investigate Home Plate and that the desire to be pointing in the right direction when the depths of winter arrive won't cause our visit to be a short one.

Bob Shaw

[Phillip]

I am afraid I do not have any imaging questions, but I would be curious to know what kind of debate surrounded the recent decision to have Spirit pass up the shelf/ledge, which looked to my untrained eyes as very interesting. Did they decide it was not very promising looking? Or that they will have a chance to study similar features later (maybe HP itself or on McCool Hill)? Or was it a regrettable but necessary result of the need to get to HP fast and then up the slopes? Depending on his answer, this may be good fodder for follow up questions giving interesting insights on the tough decisions MER team must have to make on a day to day basis.

[djellison]

Quick update, Jim and I just tested Skype, and it worked great, so hopefully we're go for the first of these on Thursday Evening. More news soon.

Doug

[Bob Shaw]

Doug:

Here's a question: will they take suggestions for rock (etc) names?

Bob Shaw

[Tom Tamlyn]

1. Please discuss your reasons for being optimistic that the rovers have captured images of meteor trails.

2. Do the MER pancams share any significant systems with the "original" pancam discussed in Steve Squyres' book? Did the original pancam have any capabilities lacking in the MER pancams, or did subsequent advances in imaging technology result in the MER pancams being more capable all 'round. [Obviously No. 2 could also be a question for SS].

3. In a recent news article, Phil Christensen is quoted as saying that the same wind events which cleaned off the solar arrays left the mini-TES lenses filthy. Has pancam encountered similar problems? [I believe that this was a 1/9/2006 Arizona Republic article mirrored by whatonmars.com, but no longer available for free]

TTT

[djellison]

3.  In a recent news article, Phil Christensen is quoted as saying that the same wind events which cleaned off the solar arrays left the mini-TES lenses filthy.  Has pancam encountered similar problems?    [I believe that this was a 1/9/2006 Arizona Republic article mirrored by whatonmars.com, but no longer available for free]

Oo - that's a GOOD one. I was going to ask about 'dirtyness' - but to have a comaprison with Mini TES is a news to me, a nice angle on it. It's IN.


Doug

[hendric]

How does the team feel about posting the raw images on the web? Does it seem like us amateurs are stealing their thunder, a little? Would you do another public raw archive on your next mission? Do you read the various forums regularly?

[Canopus]

Could we also please have a Jeffrey L. Bell Q and A??

[paxdan]

Doug:

Here's a question: will they take suggestions for rock (etc) names?

Bob Shaw

Yeah, a name a rock/feature on mars outreach project would be a great idea. Much in the same way the rovers were named e.g., get schoolkids to provide a name and reason.

Do it for a rock/feature at each site to commemerate an important milestone. (1k Sols) Give the winners a nice glossy print and you have yourself a nice PR opportunity.

[MahFL]

"MastCam also provides both natural color still and high definition video"

[djellison]

Question for Jim Bell:

The usual left cam 3-channel multispectal imaging is bands 2,5,7 <near-IR,green,violet> Sometimes we have other color combos like 2,5,6 or 2,4,7 or 3,5,7 (or some such.. I'd have to go back and check examples).

All of the alternate sequences seem to produce images with degraded color discrimination: two of the channels are too similar to each other, and you typically get images that are dominated by long-vs-short wavelength differences and the color differences due to the middle channel (reflecting curvature in the spectrum) are less discriminated.

What's the rationale behind some of these other filter sequences during only 3 filter color imaging?
Oh.. regarding HomePlate... it's obviously the fossilized pizza-crust of the gods. Heaven help us if Spirit finds 1 meter fossilized pepperoni, ...or anchovies!

This one got done, as did the one regarding aging

Doug

[algorimancer]

Here's a two part question for Jim Bell:

A) Why didn't the MER cameras use the Jpeg2000 file format specification (which is based on wavelet compression and an order of magnitude more efficient than standard jpegs) rather than using an in-house wavelet compression algorithm? Currently Nasa software must be used to view the raw image data, whereas with Jpeg2000 compression the raw images would have been immediately accessible with standard image editing/viewing software.

B) Would it be possible to post higher quality images to the exploratorium & jpl sites in Jpeg2000 format (same size, better quality) in addition to or instead of the currently used jpeg format?

Not only would use of Jpeg2000 for images in exploratorium provide better quality images, but it would also be a spur towards broader adoption of the format in browsers and other image software.

[djellison]

Currently Nasa software must be used to view the raw image data, whereas with Jpeg2000 compression the raw images would have been immediately accessible with standard image editing/viewing software.

Are you talking about the PDS IMG's - as the rules and regs for what you publish to the PDS are basically set in stone as I understand it.

I agree, better quality raw JPG's would be nice, but to be honest, so old and to date, fairly reliable is the system that's putting out the JPG's we see know, I'd not want to see it played with.

iirc, you'll get some Jpeg2000 goodness with HiRISE images though

Doug

[algorimancer]

Are you talking about the PDS IMG's - as the rules and regs for what you publish to the PDS are basically set in stone as I understand it.

I agree, better quality raw JPG's would be nice, but to be honest, so old and to date, fairly reliable is the system that's putting out the JPG's we see know, I'd not want to see it played with.

iirc, you'll get some Jpeg2000 goodness with HiRISE images though

Doug

Fundamentally I was referring to the images comming out of the the MER. As I understand it the compression used prior to transmitting the files is a type of wavelet compression (which is good), however why they opted to "wing it" versus using an ISO standard is what I'm wondering about. My guess is that the standard wasn't finalized at the time they were building the hardware, but it's just a guess. As to the PDS rules... it has been a few years since I last looked at the requirements, but since HiRISE is apparently using Jpeg2000, I would guess that MER could as well. I wonder whether the compression scheme in MER overlaps with that in Jpeg2000 so that a direct conversion would be possible without any loss of quality.

Thanks for mentioning HiRISE, I hadn't looked closely at that mission but after having a look at the home page it looks pretty exciting, particularly from the perspective of the sort of people who hang-out at this site