Like all of you, I'm excited about the fine-scale resolution MRO will provide. But something nags at the back of my mind...

I have read my copy of Don Wilhelms' "To a Rocky Moon" so often that it is in tatters... and I'm struck by one of Wilhelms' overriding conclusions from his experience in lunar exploration:

Fine-scale resolution doesn't always help you understand the geologic processes that formed a planetary surface.

Wilhelms makes the point repeatedly that, in analyzing lunar geologic processes, lower resolutions and larger scales were much more instructive than extremely high-resolution imagery. His point of view was that the high-res stuff from the LO program was mostly useful to the Apollo planners in characterizing landing site qualities, but that for scientific analysis, LOs 4 and 5, with their higher orbits and larger-scale images, were *far* more valuable.

The question I have for all of you professional (and amateur) astrogeologists out there is this: Would this observation apply to Mars as well as our Moon?

My own tentative answer to that question is... yes and no. I think that Mars preserves enough large-scale record of its early impact history (especially in the southern hemisphere) and of subsequent volcanic, climatic and erosional epochs that the larger-scale, lower-resolution imagery available from Viking (and even Mariner 9) may be some of the most useful data we have in identifying the widespread, planetwide processes that have shaped the face of Mars.

But on Mars, unlike on the Moon, there are questions of climatic history and change that can only be read at very fine scales. The Moon presents a boringly similar surficial appearance across its entire surface -- the erosional processes there are very specific and limited, and result in a fairly homogenous surface appearance regardless of the underlying geological units. This is not true of Mars, where tectonic, volcanic and climatic activity not only had a hand in shaping the planet over billions of years, but (to some degree) continue to this very day.

However, like the Moon, the surface of Mars doesn't always present clear-cut contacts from one geologic unit to another when you get down to fine scales. Like the Moon (and like Earth, for that matter), processes both constructive and destructive have in many places jumbled and made "messy" the surficial layer's relationship to its underlying units.

So... in our quest for higher and higher resolution, do any of you think we should heed Wilhelms' warning that such a desire can blind us to seeking data at more "useful" scales? Or do you think that Mars, being a different planet with a far different history, requires more investigation at finer scales than the Moon does?

-the other Doug

Yeah, LO 2 and 3 got 1m resolution from pericynthion, which was (IIRC) about 35 miles (or roughly 50 km). Obviously, such a low orbit is impossible around Mars... IIRC, the Apollo pancam had the potential to get about 50cm resolution from the descent orbit (15 km pericynthion), but its motion compensation system didn't work well at that low altitude, and so that theoretical resolution was never achieved. But I do recall quite clearly that the maximum resolution of the Apollo pancam was significantly softened (by alterations of the optics) from the level the camera was designed to provide -- and provided in those self-same KH's you mention.

I don't have the link handy, but there is an excellent image from one of the KH's taken of a Soviet battleship in dock that displays the quality of the system. You can count the containers on the deck and identify individuals on the ship, on other ships, and on the docks. From shadow lengths, you could even calculate every person's height. Resolution was on the average of 20cm per pixel or better (since you could make out human forms, including arms and legs). And this was taken through Earth's thick atmosphere from at least 200 km. To top it off, it was a somewhat oblique-angle shot, so it was looking through more atmosphere than a straight overhead image would have to contend with.

DOD was *really* unhappy when that image was leaked -- it indeed showed that their systems could resolve something the size of a license plate, though, as you said, you couldn't read it. For example, you could tell there were markings on most of the visible containers, but they were dark blurs, not readable.

So, while HiRise is absolutely nothing to sneeze at, and will return extraordinary images, you *could* get higher resolution. And while it would probably *not* have to be a Hubble-sized instrument, it would almost definitely be beyond our current capability of sending all the way to Mars... HiRise is remarkably capable for an instrument that we *can* send to Mars, IMHO.

-the other Doug

Well, for that, you'd need an X-ray machine, or an MRI...



Sorry, couldn't resist...

-the other Doug

Yeah, you'd have to use adaptive optics to adjust for atmospheric shimmer (even in such a thin atmosphere as Mars'), and that would be prohibitively heavy and expensive to get into Martian orbit...

So, we're going to see a total increase from the absolute best MOC resolution of 50cm in downrange sampling to to the HiRise resolution of 30cm in all dimensions. It might not sound like much, but it is nearly twice the resolution, and will be the standard operating parameter for the camera, not a "pushed" mode. I am SO looking forward to seeing the first images...

Will MTO's arrival in 2009 help increase the total bandwidth such that MRO and other orbiters (including possibly a *really* venerable MGS) might take advantage and toss as much down the pipe as possible? Or is MTO not designed to support other orbiters?

-the other Doug

I discovered a while back that Eric Jones' excellent NASA website. the Apollo Lunar Surface Journals, has been incorporating links to MP3 files of the air-to-ground audio. So far, it's complete for Apollos 15 and 16, and I believe is complete through EVA-1 for Apollo 17.

Now, I grew up with Apollo -- I was born 10/17/55, so I was 13 in the summer of 1969. And, just the way the dates lined up, I was 15 years old when Apollo 15 flew, 16 y.o. during Apollo 16, and 17 y.o. during Apollo 17.

I took pictures off the TV screen of the moonwalks, and I set up a microphone from my little tape recorder in front of the TV set's speaker and recorded audio of the (progressively more scarce) TV coverage of the moonwalks. For several years I fell asleep at night listening to the moonwalks, memorizing details and allowing my subconscious to fly me to the moon in my dreams...

So, when I discovered the MP3s, it occurred to me that I could download them from their source and burn CDs from them... hehehehe...

I finished Apollo 16 -- every bit of air-to-ground from the beginning of Rev 16 (PDI Rev) until ascent and injection into lunar orbit three days later. A total of 32 CDs. And I can listen to them in my car as I drive to work... *big grin*...

I guess this is just a heads-up for any other Apollo junkies out there who might want to do something similar.

-the other Doug

It's sort of interesting to see a 21st century replay of the "mode decision" taking place today.

The tSpace proposal looks an awful lot like the various EOR proposals that were being developed in the early 60s. Although I don't see how their S1 vehicle is supposed to enter Earth's atmosphere -- the crew configuration makes it look like it would enter belly-in or back-in, and it doesn't look like it has a significant TPS in either area. (tSpace *does* know that, for example, SS1 didn't have to deal with the levels of heating you get coming back from orbit, right...? And that you really *do* need a real TPS for the job?)

The tSpace operational proposal also sounds a lot like a diagram I once saw -- "To The Moon with Saturn I's or Bust!" It imagined an LOR-type Apollo mission flown entirely on multiple Saturn I configurations, with something like six to eight flights to deliver the actual spacecraft into LEO and 12 to 16 flights to deliver TLI and TEI fuel.

The Lock-Mart proposal looks nice, but I seriously question the need to carry wings and an airframe all the way to the Moon or Mars, when you're not going to use them until the very end of the mission. It seems silly to make the lunar and planetary versions of the vehicle bear the weight of a design that only really makes sense for a ground-to-LEO shuttle.

But, back to the mode decision -- the Lock-Mart version looks more like an EOR/LOR blend in its lunar configuration -- they're obviously not going to land that kewl-looking Hermes-like vehicle, with its heavy wings, on the Moon. In EOR mode, they'll put together the base CEV, a TLI stage, a landing module and a TEI stage via multiple launches to LEO. After this whole thing is assembled, they'll proceed with a classic LOR-style landing mission.

Another question about the Lock-Mart concept -- with a thin-shell titanium airframe, what do they plan to do for solar flare protection? They've discovereed that just putting the back end towards the sun doesn't really protect you, you need shielding all around you during such events... and it doesn't look like the Lock-Mart vehicle could easily accomodate a shielded area for the crew.

-the other Doug

OK -- 30cm resolution (on average) is awesome -- that's about a one-foot resolution for those of us who don't yet think in metric, right?

How does this compare to the single-axis (push-direction) resolution of cPROTO MOC images? Since the cPROTO images have been able to resolve the MERs and the MER landers (even suggesting shape), I'd have to think that they are giving at least 50-60cm resolution, at least in one axis.

IIRC, the best Apollo pancam images of the Moon had about 2m to 3m resolution, and that was deliberately softened from the absolute capabilities of the system because DOD imposed restrictions on how good they would let ITEK make the cameras for NASA (since NASA was basically asking to use the same camera system that was flying on DOD's KH surveillance satellites at the time).

This leads to the question -- is 30cm resolution *really* the best achievable, or does DOD still refuse to allow NASA to use the *real* highest-resolution imaging systems that have been developed?

And will just asking that question impose the risk of me just disappearing somewhere into the night...?

-the othe

Meteors sometimes explode into fragments as they pass through an atmosphere -- even iron meteors. Especially if they enter at a highly oblique angle and experience a relatively long duration heating event.

If a meteor explodes, say, 500 meters above the surface and propels pieces in all directions, some few pieces will have their forward/downward motion greatly reduced,and will simply fall out of the sky from there. Falling from 500 meters, such a piece will hit and sit on the surface, just like we've seen at Meridiani. Happens all the time on Earth.

At the same time, a smaller chunk could be propelled from 500 meters on to the ground and make a tiny little crater. There would probably be a footprint whose far end would have a range of craters made by the chunks that survived and continued to the ground, and whose back end was made up of chunks of meteor sitting on the ground, relatively unscathed.

Yes, it probably happens pretty rarely that a chunk of meteor is slowed down by explosion dynamics and ends up sitting on the ground like it was set there by some giant's hand. But even things that happen *extremely* rarely can be commonly seen if you wait a few billion years...

-the other Doug

Yes, but with Chemcam, how are we going to differentiate between the rock itself and the weathering "rind" found on most rocks?

Will MSL have anything like the RAT's brush, that can be used to brush off overlying dust and crust-like coverings so we can actually see the composition of the rock without contamination from dust and crust covers? I understand that its laser will vaporize a very small amount of material -- but won't most of that material be the rock's surficial layer, which (as we've found out on Pathfinder and the MERs) usually is rather different in composition from the rock itself?

-the other Doug

If I'm not mistaken, didn't Pathfinder actually detect a dust devil pass nearly over it? I remember reading a report of the event -- the wind direction changed through 360 degrees over less than a minute and the pressure shifted at all three spots along the mast where the meteorological pressure sensors were located, consistent with a dust devil passing.

IIRC, there were no visible changes in Pathfinder's area after its devil passed -- perhaps it passed overhead (i.e., a funnel that lifted off the ground and passed over Pathfinder itself)? So it's possible that instruments to detect a dust devil passing directly overhead might still not manage to let a probe capture images of it.

I think the only really effective way of capturing images of the little devils is a synoptic survey. But, hey -- any rover worth its salt can do that while performing other tasks, right? Like while doing a long Mossbauer or APXS integration?

-the other Doug

There's always one good explanation for tidy circular impressions -- craters. In the absence of any other data, I'd guess it's a very small crater from a very small impactor.

I bet the rock is pretty soft or unconsolidated, though, to record a crater so nicely without being blown to bits by such an impact...

-the other Doug

I think she'll likely move on, too -- but if she doesn't, we're in a *very* interesting place to observe weathering and erosion.

It's pretty obvious from the layering being exposed in some of the larger dunes we just started seeing recently that *some* of these dunes are ancient and, instead of being built up, are currently being deflated. Unlike water erosion and aeolian erosion of rocks, dune erosion can happen over relatively short time frames. (Of course, it depends on the grain characteristics of the dunes and the "crusting" that may have occurred at the tops of the layers within the dunes.)

The fine striations visible transverse and sometimes perpendicular to the some of the dune crests suggests to me that these are the dunes that are being deflated. Note that some of these dunes display a "crumbling" appearance near their crests, where mass wasting has begin to pull material down -- another indication that the prevailing winds have changed and old dunes are now being blown away.

If a good, layered dune is within the reach of Oppy's IDD, perhaps a combination of the RAT and using the RAT head as a rough scoop will let us do very clean, long integrations of the different layers in the dunes. Wherever the grains forming the various dune layers originated, they will tell a story of changes in the Martian environment over time.

And careful observation of even minute (but detectable) changes in the dunes around Oppy would provide some really valuable data on the speed and characteristics of aeolian deflation/deposition on Mars, maybe even giving time frames for the formation of the layers in the ancient dunes. Thereby providing the possibility of putting absolute (if inferred) dates to recent Martian climate cycles.

So, if we have to become immobile somewhere, there are worse places...

-the other Doug

I guess I've just been spoiled by the MERs and MGS, but I am disappointed in the quality of the images from Huygens. Why the very limited number of pixels per image -- was it a matter of the width of the comm pipe between Huygens and Cassini? Would it have cost that much more in terms of a weight penalty to build five or ten times more pixels into the camera system? Even in the late 80s, when Huygens was first developed, they could build higher-resolution cameras than they ended up using...

I know there was fog and haze (more than expected), I know we lost half of the images... but the image encoding from the source has introduced so many artifacts it's really hard to analyze the images to anywhere near their theoretical resolution.

Yes, there is a great deal of good information in the images and other data Huygens returned... but it's so tantalizingly close and yet so lacking in critical definition that I just want to tear my hair out... *sigh*...

-the other Doug

Whatever happened to the concept of a deployable winged Martian flier? I have heard of the balloon concept, and heard it criticized because you have no control of the direction of travel with a Montgolfier-type balloon, no ability to target specific, interesting targets to land "on top" of (within arm's reach, so to speak) and analyze.

The argument I've heard against winged vehicles is that they're a lot harder to land on (much less take off again from) the vast majority of surfaces you find on Mars. And if you're just going to stay in the air, flying around taking very-high-resolution images from a mile or two above the surface, you're not getting that much more significant data than you'll be able to get from orbiters. Being *on* the surface and able to verify "ground truth" of orbital images by phsyically examining the minerology of the rocks and soils is a required part of the process. But I've heard it argued that the resolution of remote sensing data from a mile (or even less) in the air just won't be significantly more valuable than the resolution that can be achieved from orbit. And it's a lot easier to design, fly and operate an orbiter than it is to try to deliver a winged vehicle to Mars' atmosphere...

If you didn't have the kind of capability that the MERs and (hopefully) the MSL give you, then I could see how picking up images from low altitude might be interesting, or hopping indiscriminately from place to place with a *very* small science package might be interesting... but if you're going to spend money to put really small science packages on and around Mars, why not put a bunch of netlander-type probes around to establish meteorological, seismological and radiation detection networks (and do some really basic site investigations), and leave the mobile exploration to wheeled vehicles more suited to the task?

-the other Doug

Ah, but the images taken by Spirit from West Spur looking up at the top of Husband Hill all showed a *very* dark sky beyond the hill crest. That was looking up at, what, 45 to 50 degrees? And the sky was very dark, *much* darker than the hill crest and very much darker than the sky at the horizon of the plains, even in mid-day.

-the other Doug

Exactly -- the evaporite layer was created as a body of water evaporated (repeatedly -- since there are many, many layers of evaporite) and deposited the salts and minerals suspended within the water. Since it's been a long time since there were bodies of open water on Mars, the evaporite layer has been there for a long time.

But I don't necessarily agree that there are nothing but dunes as we get farther south into the etched terrain. If you look closely at the super-resolution MOC images, you can make out the duning pretty clearly, and as dunes always do, they are alined and controlled by wind patterns. The lightest-albedo structures within the etched terrain are very definitely not alined along with the other visible dunes -- they are more like small ridges and "peaks" sticking out above the plains. More importantly, they *interrupt* the regular procession of wind-formed duning.

I'm not saying that these high-albedo structures are nice, clean, unmodified outcrops of pristine evaporite. But I think they are evaporite structures in the process of being weathered away. In which case, they'll probably look like big piles of very light sand with actual rock sticking out at various angles (and weathered rather smooth). I think there *may* be some relatively uneroded evaporite exposed as a ground layer around these little ridges, which is what I'm most interested in seeing and getting analyses from...

-the other Doug

I think most of the dimples we see are, in fact, meteor craters. The ones without raised rims are just older and more eroded.

However, I also think there is plenty of evidence for sinkhole or karst-like structures out on the plains -- especially the cracks like Anatolia. But while it seems obvious that there are voids down in the evaporite, I think we'll find that these voids are arrayed beneath the weathered concretion layer (the dark soils out on the plains) as a series of cracks defining polygonal crack patterns caused by the drying-out of the ancient seabeds. Such crack patterns are visible in a lot of places on Mars -- they're just filled and covered over here at Meridiani (for the most part) by the concretion erosion residue.

-the other Doug

Hmmm... when you look at the highest-resolution MOC imagery, it's true that you can't tell for certain if the "outcrop" is really outcrop or if it's just piles of lighter-colored sand. But if you zoom out a bit and look at a slightly bigger picture, the "outcrop" organizes itself (at least to my eye) into impact-related landforms -- ancient crater rims and "splash pattern" ejecta texturing. That argues for the areas that appear to be outcrop to actually reflect ridges in the local landform.

As has been discussed elsewhere, the blueberries seem to provide a natural cover to prevent further erosion of the evaporite layer out on the plains... and as we advance into the lighter-colored soils and dunes, the blueberries seem to be diminishing in abundance. Maybe we're getting into an area of evaporite that developed a lot fewer concretions? That would mean the evaporite would erode primarily, with no cover of concretions to stop the erosion process.

A good lesson we can learn from both terrestrial and lunar geology is that a vastly large majority of the materials at any given location on the surface of a planet originated(*) within a kilometer or two of that location. I think that argues for the lighter soils and dunes to be the eroded dust from the evaporite layer. I bet the IDD work will show these soils and sands to be very similar in composition to the evaporite layers.

-the other Doug

(*) -- when I say "originate," I'm talking relative to the local landforms. Obviously, large-scale cratering tossed a lot of the original crust around, especially in the ancient cratered southern highlands. But ever since the last of the great impacts and the last of the great floods, I'd bet that nothing much has moved more than a few kilometers in any given direction, with the exception of a very thin layer of dust. DVD

I have two things to say.

First, we need to remember that Mars is an entire planet, with complex landforms and weather patterns. While its atmosphere is far thinner than ours, it obviously changes in appearance over time and with regard to a number of different conditions, sometimes as frequently and dramatically as our own. So there really isn't such a thing as any one way the Martian sky appears -- its appearance changes during the course of the day, during the change of the seasons, and during changes in weather. Just like on Earth. (Now, as for me, I want to have a feeling not just for how the sky generally looks, I want a feeling for how it changes, and what conditions make it change in given ways... *smile*...)

Second, I think it's really, really fascinating how much most of us want to be able to visualize exactly what it would look and feel like to stand upon the surface of Mars. We want to know what the colors would be like, we want to know what the horizon would look like, and we especially want to know what the sky would look like.

I don't think there is any rational reason for a lot of us to feel so strongly as we do about this desire to *know* what it feels like to have Mars under our feet. (Or the Moon, or Titan... any and all places we can imagine ourselves.) But it's this desire that needs feeding, and it's this desire that drives and justifies the continuing exploration of space.

Rational or not.

IMHO.

-the other Doug

ps -- personally, from what I've seen, in my imagination I see Mars' sky as something that thins out so dramatically overhead and brightens up so dramatically along most of the horizon, with transitions from bright butterscotch to dark, dark violet, that it will give you a visceral sensation of how thin a skin of air surrounds you. If you've ever flown in an airliner at 35,000+ feet, you know how you can just sense the thick portion of the atmosphere, defined by how most of the clouds and haze float atop it? Well, on Mars, I think you'll be able to "feel" that layer as you stand at its bottom -- it will feel like a very shallow pool, indeed. DVD

It looks like fine-grained sedimentary rock that's not *quite* as finely layered as the evaporite at Meridiani. It doesn't seem to show much in the way of concretions, concretion pits, or vugs (though you'd probably have to RAT some of the rock to really see if it had vugs).

If it's ashfall- or aeolioan-deposition sandstone, the layers look pretty thin... but not so thin as to completely preclude either.

However -- and this is a big however -- is it just me, or is there cross-bedding present in a lot of the layering in that rock? I see a lot of the layers forming into little crescents, just like in the rocks at Meridiani.

If that *is* cross-bedding, I'd bet that these are liquid-deposition sedimentary rocks.

In any event, the minerology investigations are going to be *very* interesting on this one... *grin*...

-the other Doug

I never thought I'd ever say this to anyone, but... maybe, just maybe, you ought to lay off the science fiction for a little while...?



-the other Doug

Well, of course, you're right -- there's likely no really good economic reason for settling off-planet. Except, of course, for ensuring the survival of the human race in the case of an extinction event on Earth. But, of course, if that happened, none of the people who put up the money for off-planet settlements would be around to worry about economic gains or losses, and since all that's apparently important in the universe is for rich people to keep amassing as much wealth as possible, then, of course, your argument is unassailable...

...*sigh*...

I have an idea -- let's let all the people for whom bean-counting and the amassing of wealth and power define the purpose of human existence stay here and play with their funny colored slips of paper. The rest of us can go to the stars...

-the other Doug

Time to fill out the remaining dark corners in the Surveyor program's history...

(A) The original Surveyor program included both orbiter and lander versions. Mostly for management reasons, the Surveyor people got the orbiter taken away and were told to concentrate on developing a soft lander that would work. When a need for an orbiter was still keenly felt, the prosaically-named Lunar Orbiter program was conceived and funded (but given to another contractor).

( Until fairly late in the development cycles of the later Surveyor block modes, there was a Block III design that used a modified Surveyor landing "base" to deliver a small roving vehicle. The entire science package, including the camera system, was located on the rover. For a time, as a last-ditch attempt to extend the Surveyor program, several groups were proposing that NASA skip the Block II flights and go directly from five or six Block I's to Block III rover flights. But the design team continued to have problems, the weight of the vehicle was going to need a more powerful booster than the Atlas-Centaur, and Apollo loomed in the very near future. So an early American lunar version of the MERs (and of Lunokhod) died a-borning.

There is some nice, if spotty, information about the Surveyor rover development attempt in Don Wilhelms' excellent "To a Rocky Moon." Unfortunately, I've never found any drawings or conceptions of any of the designs.

-the other Doug

I've seen the kind of dark patch we see in Gusev in several other Martian craters, so I think these "baby" dust devils are controlled by the topography. I can easily imagine the circular crater rims of these large craters setting up instabilities that result in baby dust devils scouring these relatively small patches of ground.

I think the atmospheric processes that control the large dust devils are probably a little different from those that control these baby devils. But the fact that both species of dust devil exist on the same planet is indeed fascinating... *grin*...

-the other Doug

Many of the missions you list weren't designed, managed or operated by ESA. Yes, there is a good amount of experience *worldwide* in various aspects of spacecraft design and operations, and even mission/program management. But we must remember that, according to stories I've heard, the NASA/JPL people told the Beagle 2 designers that American airbag-landing success was based on combining airbags with a terminal phase rocket brake, and gave Beagle 2 a far smaller chance of success than Pathfinder or the MERs because ESA decided they didn't need to bother with a rocket brake at the end of the descent.

And thus, Beagle hit and went splat.

The only way someone else's experience can benefit you is if you heed the other person's advice...

-the other Doug

Quick edit -- I really should say ESA decided they couldn't afford the weight of a terminal rocket brake, not that they couldn't be bothered to use one. I guess my disappointment over the somewhat-predictable failure of Beagle 2 still makes me a little bitter... *sigh*... DVD