Come up with a believable mechanism by which contact with the arm could have generated the *opposite* result to what we've seen every other time it's been pressed into the soil, and I'll grant you the point.



-the other Doug

There is absolutely no sign of APXS or Mossbauer contact plate impressions on the soil in the area in question, in your "after" shot. And besides, in every other experience we've had with Meridiani soils, when you press down on the soil, blueberries are shoved *under* the fines and disappear from view.

Oppy didn't exhume those blueberries. There is no conceivable mechanism by which they could. Especially not without any other signs of soil disturbance. (Maybe, just MAYBE, if you RATted the soil, you could exhume buried berries. That has very obviously not happened here.)

If some berries are visible in the "after" picture that weren't visible in the "before" picture (and I agree, there are), then the dust that had been covering them has to have been swept off.

By the wind.

Clean sweep party, anyone...?

-the other Doug

I have what I believe to be a little news about "Roving Mars." However, it has the potential to annoy some of y'all over on that side of the pond.

Ya see, the Discovery Science Channel runs what they call "Space Week" once or twice a year. At those times, they premiere several new space documentaries (which they then re-run, once or twice a month, for a year or more). Sometimes these are new documentaries produced by Discovery, sometimes they're programming originally developed for Australian or British audiences (like slightly re-edited episodes of "Horizons," for example).

The ads for the upcoming Space Week, which starts in a couple of weeks or so, are listing titles of new programs that will be airing then on Discovery Science.

One of the titles listed was "Roving Mars."

I dunno if they're just going to run the IMAX piece, reformatted for a much smaller screen, or even if it's an entirely different project. But somehow I doubt it.

So... the annoying thing for y'all is that you're finally getting to see the thing all of about two weeks before it appears on cable TV here in the States.

The redeeming fact is that you'll be able to watch it in IMAX, which is a really great experience in and of itself.

-the other Doug

Anyone else following this story? Someone who works in Building 44 at the Johnson Space Center outside of Houston (the Communications & Tracking Development Center) apparently came into the building with a handgun. One to several shots are reported to have been fired. An *unconfirmed* report says that a meeting was taking place in a conference room when the alleged shooter walked in, pointed the gun at one particular person, and told everyone else to get out...

CNN may be about to confirm that last story, though.

I hope no one we know works at JSC or in/near Building 44.

-the other Doug

I don't think the bays give the asymmetry here -- I think it has to do with the uneven height of the rim. Wind will enter the depression along the lowest points of the rim, and that likely determines how and where it spins up its racetrack pattern.

In fact, there are some indications that, at some times of year, the racetrack wind pattern in Victoria changes from counter-clockwise to clockwise. Look at the muted streaks coming off the western side of the crater -- those seem to indicate a spin in the opposite direction from the streaks off the north-northeast side of the crater.

Hey, maybe that explains why Victoria has bays and other, similar-sized craters in this same area do not. Victoria is situated on a slope, and that slope allows its internal wind pattern to shift seasonally. So, instead of a billion years of counter-clockwise rotation, it sees seasonal switches in wind direction, which enhances aeolian erosion along the crater rim. So, the same winds that would otherwise have reinforced the circularity of the depression by eroding everything in the same direction all of the time instead do this seasonal push-pull routine, which encourages greater and greater erosion along the rim. Probably also generated the overhangs and undercutting we see in the cape cliffs.

-the other Doug

Here's another little gedankenexperiment for those of you who are having a hard time understanding why there are only streaks from some of the bays, and not all of them...

Prop a bicycle up so that one of its tires is free to rotate, without touching the ground. To take gravity out of this little experiment, set the bike on its side so that the wheel's axle is perindicular to the ground. Now take a garden hose with a spray attachment and spray a high-pressure stream tangential to the tire, to spin it up.

You'll find that the water which stays on the wheel as it turns will be sprayed off primarily from a fairly small arc of the wheel, about 120 degrees in the direction of rotation from where the main stream is hitting the tire.

It has to do with momentum and how long the material can be accelerated before the force holding it to the wheel (adhesion, mostly) is overcome by inertia. And it has to do with the original vector and location of the water stream.

Similarly, wind spun up inside a shallow bowl isn'g going to stream out of every available bay equally -- it will spin out where its momentum tosses it out, and since the pressures within the crater aren't even, that will be somewhere between 120 and 270 degrees "down-rotation" from where a majority of the wind enters the crater.

So -- the answer as to why Vicky streams her streaks out where she does is because of the direction of the prevailing wind, where the wind primarily sinks into the crater, and where the pressure bulge of that wind's entry tends to push it back out.

-the other Doug

The angled plumes of the dark streaks are indicative of a "racetrack" wind flow within the crater that breaks out at the north and northeast bays.

Think of a bowl of soup. Half-fill a bowl that has several scallops in its rim and begin swirling the soup in the bowl -- in this case, counter-clockwise. When the soup rises high enough along the sides of the bowl, it will stream out of the lowest scallops in the rim and continue on in a line that starts out tangential to the rim, but that sweeps out from that tangent as the materials flows outward. Leaving exactly the kind of "broken leg" pattern we see at Victoria.

Martian craters seem to be very good at "spinning up" the winds within them into racetrack patterns. If the coriolis forces are strong enough, and if the surface heating conditions are right, this spin-up can cause organized vortices (i.e., dust devils) to form. Even when dust devils don't form, though, most craters still develop these racetrack-style wind patterns. It's quite common to see signs of such racetrack patterns as they blow out of low spots in crater rims.

-the other Doug

Yeah, that would likely convince me (though, while I still lean towards clean-sweep, I'm not comfortable that it explains the apparent medium-grained cover over the intermediate-sized soil grains in the on-streak soils). If deposition is the correct theory, I would also expect to see a similar relationship in larger dark grain size from the sides of the streaks into mid-streak. Considering the feathered appearance of the boundaries, if the streak comes from the wind's dispersal of a fount of dark material coming out of the crater, then deposition ought to peter out at a predictable rate as you move to the edges in any direction.

That wouldn't convince me as much, since both deposition and clean-sweep could result in clear compositional differences -- especially at the resolution available. If you could prove to me that there are compositional *matches* between the streak soil and the occasional darker spots within the crater, that would convince me more -- but not entirely, since both could be areas where similar underlying material is being exposed by deflation.

Problem is, not even the APXS and Mossbauser are capable of resolving the composition of individual soil factors. And mini-TES is nearly useless for such a fine-scale resolution. We get good data, but there's a limit to its resolution. And composition of individual soil factors is beyond that limit.

I fear that, without being able to say "yes, the soil here has 12% more grains of this mineralogical characterization," or somesuch, the averaged compositional data we get for soil will only fuel speculation, not provide definitive answers.



-the other Doug

Here's an explanation for the lack of the smaller, what people are calling intermediate grains, on-streak.

The intermediate grains (smaller than the concretions, larger than the soil grains) are likely *not* hematitic concretions. They may well be busted-up pieces of the evaporite.

Perhaps the higher wind conditions in the streak areas have eroded these small grains away to nothing, while the winds just aren't strong enough to erode them down further outside of the streak areas?

I think we need to look at compositional answers for why these smaller grains are missing on the streaks...

-the other Doug

That was an excellent summary, Don -- it demonstrates what I've been saying all along, that the limitations on most every human endeavor have more to do with financial and schedule pressures than they do with the limits of our technology or imagination.

Now, as we all know, there are a lot of ways to automate the processes you discuss. Heck, back in Gemini days, more than 40 years ago, command loads to the Agena target vehicles were sent up pretty much exactly as you describe, here. But even back then, they had an automatic comparator that would check the command load as sent against the command load as received by the Agena. Only when that comparator failed did they end up digging through printouts of the command loads to verify that the load was properly received.

Now, that's not exactly the same as comparing an actual command load to a desired command load, but its similar in process. And thus, the technology to error-check a lot of this stuff has been around for a long time.

As you have so effectively pointed out, the ground support stuff is usually designed (or used off-the-shelf) to do its job, bare-bones, no extras. Error trapping is almost non-existent.

And lest anyone think that this is just an issue with ESA's efforts, recall that an average command load to the MERs requires most of an individual's workday to prepare -- seven or eight hours. We all know it's *possible* to create error-trapping front-end software for such things that would allow a rover driver to tell the front-end interface: "We want to drive 20 meters in this specific direction, take the following image series, and then prepare for an overnight Odyssey pass." It's very possible to set it up so that creating and radiating the appropriate command series would take the rover driver 10 or 15 minutes, and the front-end would ensure that all commands sent to the spacecraft would be safe and properly executable. Why isn't it done like that? Probably because it would have cost too much in time and money to develop such a front-end system in the first place...

-the other Doug

Hey, MII -- I didn't mean to sound negative, there. And, I note, in the first 'graph of your post, you did say that both of the events you described are, indeed, unlikely in and of themselves.

My whole point, here, is to try and drag the reins back a little bit on the horse of unbridled speculation. The "pipes," as they have been called, that have been speculated upon elsewhere on Mars are considered to be extremely ancient remnants of water transportation along joints in rockbeds. The speculation is that these "channels" might have transported water several billion years ago. There is no connection whatsoever between that theory and any theory of any still-liquid underground aquifers on Mars. The gullies that have been observed seem to be explained best by ice deposition on crater walls, direct from the atmosphere, which is then protected and warmed for long enough to exist as liquid water very close to the surface. For a very short period of time.

What I wanted to take strong exception to is a statement like "We want to spend time and energy looking for recent water activity, which is made possible by the discovery of water transport pipes within the crater walls." As I have mentioned, that statement is simply not true -- there are no signs of recent water activity within Victoria, the "pipes" are likely to be nothing more than linear joints in the rockbeds that existed before the Victoria impact, and even if these joints did once transport water, that hasn't happened in a *long* time, probably billions of years.

Fair 'nuff?

-the other Doug

That's my impression, too -- and a good part of my rationale to answer Fred's questions. Though the question of basalt isn't the right one, I think -- I believe that the ubiquitous red dust is actually oxidized basalt.

In regard to "clean sweeping," though, I'm thinking that you're right, the dark soil components on Mars are, in general, composed of larger grains than the brighter, redder dust. They move primarily by saltation and secondarily, for grains in the small end of the size range, by aeolian transport. Martian winds pick up the lighter, smaller-grained redder dust, and keep it in atmospheric suspension, more easily than they can pick up or keep suspended the larger, heavier, darker dust grains.

That has two different consequences:

First, a wind across the Martian surface will tend to sweep away the brighter, redder dust and deposit it thinly downwind. For a given set of wind conditions (i.e., wind speed and direction), this will set up a dynamic equilibrium after a certain time, during which areas that are more exposed to the winds are swept of bright dust to a greater degree than upwind sweeping re-deposits similar red dust. These areas slowly become darker, creating the wind-generated darkening events that have been visible even from Earthly telescopes for centuries. When wind patterns change (which they do, seasonally), portions of the terrain that are darkened may brighten, and other areas may darken. But the thing to remember is that, under each type of prevailing wind pattern that a given spot on Mars sees in a year, an equilibrium is reached and given areas are swept clean and darkened more than they are re-brightened by re-deposition. But, and this is the important point, *nowhere* on Mars is seeing *just* dust deflation or deposition. Both processes are always happening, everywhere -- it's all a question of which process, deflation or deposition, is dominant over a given landform at a given time.

Second, each type of dust, the bright red stuff and the darker gray stuff, exhibits a range of grain sizes. While bright red dust can be swept off from the darker gray dust, the smaller grains of the dark gray stuff will also be picked up by the winds. Because these darker grains are larger and heavier than the lighter red grains, they fall out of the air much faster and more easily. They don't stay suspended in the air for nearly as long, and aren't swept as high off the ground. So, in an area that is being swept, you'd see the smallest grains of the dark dust (which are still larger and heavier than the largest grains of bright red dust) piled up in aelian forms, in the lee of rocks and protrusions where turbulence degrades the wind's ability to keep them suspended. That's why it's important to see how well sorted the grains are in the dark aeolian forms -- if they're very well-sorted, it indicates that the dust that's forming these dark aeolian forms is dropping out from suspension because it all becomes too heavy to be supported when the wind hits the lee of the protrusion. In other words, it's not being deposited from very far away, this material is being picked up from the ground inches or feet away from the dark dune, moved the very short distance the wind can carry it, and being dropped as soon as the conditions keep it from being suspended in the air.

That's also probably why Victoria's dark streak seem to feather out from the center -- the bright dust that gets removed is deposited hundreds of meters, if not kilometers, away, while the small amount of dark dust that the same winds can transport only gets a few meters away from where it was picked up. So, along the edges, the darker dust actually does get deposited over the brighter dust at the margins, giving it that feathered look.

All of this explaining of what I think I'm seeing is moving me back towards the clean sweep side of the fence...

-the other Doug

Not necessarily, though I've moved from smack in the middle of the clean-sweep camp to somewhere on the fence, at the moment.

On the side of clean-sweep, it seems to me that if dust was being removed from the streak in general, a well-sorted amount of that dust would tend to fall out behind uneven, jutting protrusions (like rocks). That sorting might well favor heavier, larger-grained (and darker) particles, while the lighter dust (both in mass and in hue) blows further away.

If the dark dust is blowing out of the crater and being deposited, I'd expect it to pile up on the upwind side of the rock, not the downwind side. If it takes a rock to make the dark dust pile up, I'd argue you're seeing the minor movement of dark soil components, not dust blowing out from the crater.

Of course, without a good model of the wind dynamics in and around this crater, it's hard to tell just what's happening, here...

-the other Doug

That's an awfully premature conclusion. A *lot* of things can cause relatively straight-looking linear formations (like the roughly linear formation along the NE rim). Just because someone, somewhere has *hypothesized* that other linear features in entirely different landforms that look something like what we see in Victoria *could* have been caused by water traversing along a joint in the rock doesn't automatically make these features in Victoria "pipes."

That and the *only* thing that has ever been seen and hypothesized as a sign of recent surface water movement are gullies on crater wall slopes, and there isn't even the first hint of such things here at Victoria.

So, the hypothesized ancient "pipes" (if that's what they are) seen elsewhere on Mars are not thought to be associated with recent water activity, and it's only a somewhat wild speculation that the linear features in Victoria have a similar origin to other supposed "pipes." And, of course, the only sign that anyone accepts as even potentially showing signs of recent water activites, gullies, aren't evident at Victoria at all. Anywhere.

Other than that, yeah, you've got a good suggestion there...

-the other Doug

The problem is, the Moon doesn't really have any jagged peaks. Even around Tycho. Take a look at the pans from Surveyor VII -- even that close to Tycho's rim, the landforms are *still* all softened and rounded-looking.

-the other Doug

Just recall the fiasco that ensued when NASA, as a PR gimmick, brought America's oldest living person (I think he was more than 100 years old) out to the Cape to witness the Apollo 17 launch. This old guy was stout in his belief that no one had ever gone to the Moon, and after viewing the launch, his only comment was "I seen they went somewheres, but they sure as hell ain't goin' to the Moon!"

You could actually place Hoaxland onto a spaceship, fly him to the Moon and make him go and touch the remains of the Apollo equipment, and he'd *still* insist you were faking it somehow...

-the other Doug

Interestingly, The Weather Channel's website has recently rolled out a new visualization for their radar/satellite map display. It resembles Google Earth, in that you can zoom in to very-high-resolution aerial photography (where available). Until you get to the highest resolution views, you can even overlay real-time satellite and radar imagery (with your choice of transparency) over the aerial photography.

I don't recall offhand who provides the actual photography used on this site, but I can tell you that, at least for the area right around my own house, it is of higher resolution than that offered by Google Earth (and the Google Earth view is comparable to the best resolution available anywhere in Google Earth). I have no idea what the actual resolutions are, but if the Google Earth site is giving 50cm resolution, I'd have to say that the Weather Channel site is giving at least 30cm resolution. At least in my neighborhood.

The Weather Channel site is also more up-to-date -- the Google Earth images of my neighborhood show a local light rail system still under construction, when it has actually been finished (and is shown as finished on the Weather Channel site) for a good two years, now.

-the other Doug

When you consider that one of the next few flights of the Shuttle after Challenger was scheduled to be the launch of Galileo on a Centaur loaded into the Shuttle's cargo bay, it may not be completely correct that "interim" was a misnomer. There were plans, as of early 1986, to use the Centaur / Shuttle combination for a variety of large payloads, including planetary probes.

Of course, if you talk with Shuttle experts and afficionados, you'll hear the opinion that while Challenger was a tragedy, maybe it was a good thing in one way -- that the systems in place to fly an LO2-LH2 Centaur stage inside the cargo bay were so dangerous that we would have lost an orbiter trying to fly in that configuration. (Just the systems designed to allow fueling of and boil-off from the Centaur stage, IIRC, required major Shuttle safety waivers to be allowed to even be considered for a flight configuration.)

But it's good to remember that while the full "space tug" system was never going to be developed, there were plans to go beyond the PAM / IUS set of capabilities. And, therefore, "interim" wasn't necessarily going to be a completely dead concept. (Up until Challenger, of course, after which even the PAM / IUS configurations were considered too risky and phased out.)

-the other Doug

The other attraction of Triton is, of course, that it is almost definitely a captured KBO. A Neptune orbiter would give you both a good look into the satellite system of an ice giant *and* an opportunity to study what may well be a prototypical KBO.

For my money, though, I think we need to wait for the next major breakthrough in propulsion technology. Then we may be able to launch an unmanned probe to *both* Uranus and Neptune -- and even have a chance of letting all of us see the data in our lifetimes!

-the other Doug

I imagine there are electron microscope images of dirt out there somewhere... oh, you meant from orbit?

-the other Doug

Oh, of course, Phil -- that's exactly what I meant. It's those relatively few things that you mention (mostly special features and things like block population counts) that lend themselves to the very high resolution offered by LRO.

When you consider that LRO is designed primarily to support future manned lunar operations, it's instructive to remember that while most Apollo landing sites had imagery available at between 1 and 3 meter resolution, some of the later sites (particularly Hadley) had much lower-resolution imagery available pre-flight. I believe the best Hadley imagery prior to Apollo 15 was at 22-meter resolution, and was obtained by LO IV. And that photogeologists, straining to bleed data out of imagery that just didn't contain it, were capable of badly mis-identifying small landforms as volcanic when they were primarily impact-related (as with the 3- to 5-meter resolution images used to plan the Apollo 16 landing at Descartes).

All I'm trying to do is make sure we don't forget lessons learned, here, when it comes to lunar geologic investigations. On a world where erosion and landscape modification is now extremely slow, but which has been almost completely gardened, vertically mixed (and somewhat horizontally mixed) right at the surface, you have to carefully select targets which will actually give you greater insights with very-high-resolution imagery. (Remember, Apollo astronauts had a hard time determining rock types, even when they held the rocks in their hands, because they were usually very dust-covered. John Young on Apollo 16 quipped that one rock was so dust-covered that it "defied description." If you can't tell anything about a rock when you hold it in your hand, how much are you going to be able to tell about it at 50-cm resolution?)

And, just to add my voice to the chorus, yes -- Ina is a definite must for detailed imagery. It's one of those places where the very high resolution might provide some real answers...

-the other Doug

Boy, it really is hard to tell from these two MIs, isn't it? I notice a strong specular reflection from the concretions in the sunlight, which I don't recall seeing (at least not in such a pronounced fashion) on blueberries in other areas.

I wonder if perhaps that wouldn't indicate that the berries have been sandblasted here, by very small-grained dust particles? Polished, as it were? I find it hard to believe that the relative darkening of the berries (if that is, indeed, what we're seeing) is due to a dust coating. That would have to be *awfully* fine dust, to simply darken the surface of the concretions without any individual grains being visible.

Some of the concretions also seem to sit in shallow bowls of the fine-grained soil. I would think that would be indicative to deflation rather than deposition, but I could be wrong...

-the other Doug

That's the real problem, isn't it -- finding things that didn't make obvious craters.

Lunar Orbiter images showed us one landed Surveyor (the first one, out by the Flamsteed Ring) and, as I recall, one of the Ranger impact craters (the last one, in Alphonsus). The Apollo panoramic camera showed us landed LMs, S-IVB impact craters, LM ascent stage impact craters, and even a few of the Ranger impact craters.

But no lunar orbiting camera has ever shown us Luna 9, Luna 13, or either Lunakhod (mostly, I'm sure, due to large uncertainties about their locations). And as you point out, none of the Surveyor retro-rocket systems has ever been imaged.

And the problem with that is we can see the craters formed by man-made objects 'cause they're usually fresh, blocky and rayed. Anything in the field of view in an area we *know* contains an artificial object's final resting (or splatting) place that shows signs of being quite recent becomes identifiable. But a lump, between a third and a half meter across, and thus at the extreme range of single-pixel coverage in a given iimage?

You'd have better luck finding a thoat in MRO images...

And someone correct me if I'm wrong, but I don't believe that LRO can achieve any greater resolutions from its planned specification by lowering its orbit -- the relative speed of the spacecraft over the lunar surface would cause blurring of the image, no matter what you do. (LRO already uses motion compensation, IIRC, so there's not much further you can do to achieve greater resolutions.) So, don't be expecting imagery of bootprints around landed LMs any time in the near future.

Finally, when it comes to the overall topic, here, we want to be very careful about high-reolution imagery on the Moon. The ubiquitous regolith and massive gardening of the upper crust actually make it *more difficult* to observe lunar geologic processes at high resolutions, not easier. For scientific purposes, LRO's resolution needs to be used for such things as stereo slope mapping and observation of small features that have an intrinsic interest. For example, you might want to take high-res images of the dark-halo vents in Alphonsus, since those might be places where gas is escaping and disturbing surface materials. Beyond that kind of thing, the Moon is better observed, geologically, at lower resolutions. (Read Don Wilhelms' 'To a Rockey Moon' if you don't believe me... )

-the other Doug

Rocket stages in a vacuum are usually vented through the engine bell(s). That way, you don't need to design any separate venting system; all you have to do is activate the proper pumps (the ones that feed the fuels to the combustion chamber during flight) and your fuel or oxidizer goes flowing out of the bell. (You could actually vent hydrogen and oxygen at the same time, though I don't think they do that all that often... hypergolics, of course, you vent separately.)

Yes, these vents can be somewhat propulsive, but not nearly as propulsive as when the engine is actually operating (i.e., when the fuel and oxidizer are undergoing combustion). Apollo S-IVBs were sent on their post-TLI trajectories (often designed to crash into the Moon) using, in part, the propulsive effect of their fuel and oxidizer venting.

-the other Doug

Now that we're finally about to do a detailed inspection of the darkest of the dark streaks emanating from the north-northeast portion of the crater rim, it's time for final speculations before we know the truth of the matter.

I'm in the clean-sweep camp. The large-scale orbital observations make these streaks appear almost definitely of aeolian origin -- the manner in which the streaks feather along the edges, and the way in which they curve off as they extend out from the crater, are all consistent with wind/ground interactions.

Observations of the lighter, western streak seem to show more visible concretions right up on the surface. If this holds true of the darker streak, I think that proves the clean-sweep theory.

Think of it this way -- if you packed pebbles and dry dust as a pavement and then let the wind strip away at this surface, the dust would blow off and the pebbles would remain. What dust remained would sit in the lee of the pebbles.

This seems to be exactly what we're seeing in the first dark streak -- the lighter soil component has been blown away entirely, and the darker component (probably eroded concretion material) has been mostly blown away but its remnants sit in the lee of the concretions.

I would expect that any depositional streak would appear as dust or fine-grained soils which cover over the materials we see on the surface outside of the streaks. That's *not* what we're seeing.

In addition, I'd have to treat any suggestion that the blueberries themselves are being blown out of the crater to form the streaks with an awful lot of skepticism. Martian winds aren't strong enough to move the relatively large-and-heavy concretions along level ground -- it would be absolutely impossible for these thin-air winds to have blown them entirely out of the crater and up to a crater diameter's distance away.

Now, if the MIs in the darker streak show that dark dust is consistently filleted on the upwind side of the concretions, and shadowed with less dust downwind of the concretions, *that* would be an indication that the streaks are depositional. But, so far, that's not what we're seeing.

-the other Doug