While I got a good view of this eclipse, I didn't take a long one. Here in Frostbite Falls... er, um, Minneapolis, Minnesota, it was about four below zero F (~20 below C) during mid-eclipse. It's down to about 10 below now (somewhere around 23 below C)... good for clear air, not so good for comfortable outdoor viewing.

-the other Doug

Doesn't this have a rather negative effect on the theories that Iapetus' dark face is simply that moon's natural surface after white snow-like frost has been sublimated off?

If the dark stuff is of similar composition all around the Saturn system, then you'd have to think it was all emplaced exogenously via some form of a mantling process, wouldn't you? Doesn't that fly in the face of what the "experts" had decided was going on at Iapetus?

Doesn't surprise me, though -- Iapetus still looks like its dark stuff was exogenously deposited to me. I've never been convinced by the strip-off-the-white explanation for a majority of the darkened Iapetan surface.

-the other Doug

Everyone, quickly, get on your knees and pray! Some great evil monster has swallowed up the Moon!



All seriousness aside, it's a really visually stunning eclipse. I don't have the proper imaging equipment, or I'd take a pic and share it. As of about five minutes ago, there was a nice bright white rind along the southeast limb, and the rest of the face of the Moon was colored a lovely shade of copper... *grin*...

-the other Doug

CNN just ran the story about 20 minutes ago, reporting a hit. No details, and no information whatsoever about how direct the hit was. The only "information" given was that the satellite was traveling at orbital velocity (first cosmic velocity to our Russian friends), roughly 17,500 mph, and the impactor was going about 5,000 mph in the opposite direction. (Yeah, I know, it's olde English imperial units -- but it's CNN, after all.)

-the other Doug

A very simple way to check if you're using the right construction is to replace the noun that naturally ends with an 's' with a noun that doesn't. In this case, let's replace it with the noun 'Viking' (another planetary lander), and the result:

"the Viking's landing site"

does read poorly. In this case, obviously, you don't need a possessive at all. It all hinges on the use of the definite article -- without the 'the,' you would use a possessive form.

-the other Doug

Ugordan -- you're right, they're wrong.

-the other Doug

I will point out that, at least according to a lot of recent reports, *all* life on Earth is descended from extremophile organisms -- i.e., organisms that had adapted to conditions in which life as we know it could not have started.

At least on Earth, life is adaptable enough to adapt to *global* conditions in which it could never have begun. Is there any reason to believe that life on Mars could not have done the same thing?

-the other Doug

Heck -- I'm four years younger than he is, and I don't see myself doing it, either... *sigh*... (Not that I wouldn't mind having the opportunity!)

-the other Doug

Well, I've watched the piece twice, now. My instant assessment is that about 20% of it is good and interesting, and 80% is an attempt to artificially generate drama where none existed.

There were some very nice things in the piece. Especially interesting were filmed sequences from within the Lunakhod driving facility, where the real-time TV images the drivers used to navigate the vehicles were seen in tantalizing, shadowy, bar-flipping snatches in the background. Fairly well done were the landing, drive-off and roving animations.

However -- if you listen to this documentary, the Soviets had two and only two programs in place to try and challenge the American assault on the Moon: the manned program (illustrated only by N-1 launch failure footage) and the Lunakhod program. No mention whatsoever of the sample return program, and only about 12 seconds of mention of other Soviet lunar probes (specifically, Luna 9). In fact, they mention the lauinch failure of the first Lunakhod attempt in early 1969, and then stated that while the Americans landed on the Moon, the Soviets were preparing a second Lunakhod as their response. Ummm... no mention of the attempt to grab a sample and return it while Apollo 11 was in flight? Really!

The writers would have you believe that the Soviets felt that wheel tracks on the Moon were a massively more impressive achievement than footprints. The writers also seemed to *share* the disappointment of the Soviet Politburo when they say that the Lunakhod achievements brought worldwide acclaim to the engineers and technicians who brought off the missions, but didn't impress anyone with the ability of the Communist system to do such wondrous things.

There were other almost offensive statements -- things like stating that a roving vehicle on another planet was a concept that the Americans never even dreamed of trying to accomplish for more than 20 years after the Soviets did it. I guess their writers never saw the plans for roving Surveyors and Vikings...

Also, unlike the information given by Alexei Leonov, who trained to land on the Moon, not a single word was spent on the concept that the Lunakhod was originally developed as a personal conveyance for a moonwalking cosmonaut. Indeed, you'd never know from this show that the Russians planned to use a Lunakhod to check out a manned landing site and provide a radar beacon for the Luniy Korabl as it descended, much less that it would then provide mobility for Leonov and his followers-on to rove around the surface.

Finally, on a more personal level of irritation, the narrator made the decision that the "kh" construction in Russian is pronounced by totally omitting the "k" sound. He called the probes "Lunahod" throughout the program. I may not be an expert in how to pronounce Russian, but I was always under the impression that the "k" was indeed pronounced, with something of a glottal stop added by the "h". It just made it sound like they were discussing a lunar brick carrier and not a "Moon walker," as the writers translated it.

All in all, some good, new information and views... but so overwhelmed with revisionist history and self-congratulatory backslapping that it rates only about a 2 on a scale of 1 to 10.

-the other Doug

I can't agree with you more, Fred. In fact, there is a post in here (likely in this very thread) in which I argue fairly strenuously for heading north-northeast and visiting a set of three craters that are relatively close to each other, but which have very different apparent morphologies. (Being the imaginative fool that I am, I named them A, B and C, if I recall...)

As for Ithaca / Big Crater, this thing looks big enough to have been formed at the end of the LHB. It has undoubtedly raised a lot of the strata that underlies the evaporite paving of Meridiani Planum into its rim hills, which would provide incalculable insight into the history of the region. But -- and it's a big but -- that material will have been heavily shocked and jumbled, covered by subsequent deposition, and difficult to find windows into.

Ithaca might be a very good target for a brand-new rover that lands within a km of its rim hills, but I doubt Oppy, even if she could get there, will have enough left in the tank to scrabble around and do a good job of characterizing the geology of the place.

So, my vote would be to exit the area (if that's what we feel we need to do) on a north-northeast vector, find the flattest tarmac we can, and investigate as many different crater morphologies as we can before she becomes a stationary lander mission.

-the other Doug

Well... we're still in predictive territory, in that we seem to be able to make the definitive statement "increased power draw means the wheel *will* fail at some point in the future." In other words, what we *can* do is infer from Spirit's example that the behavior we're seeing on Oppy means we've begun a failure mode; what you're saying we *can't* do is apply the Spirit example any further than that, to determine how that failure mode will play out in terms of time and use.

I understand your points, Doug and Nick. I will also say that they remind me of a basic argument that occurred during Apollo, the grand debate as to whether you could ever test flight hardware enough to ever determine its failure modes. There was one camp that believed it was insane to commit humans to systems that hadn't been tested hundreds of times, and another (the winning camp) that said you test to ensure the design is correct, but that there is no way to economically test every system enough times to get enough data points to make accurate failure mode predictions based solely on your test results. That second camp, the ones who invented and championed the "all-up" testing philosophy, understood the physics of their systems so well that, in some cases, they could use *single* data points to accurately define and predict failure modes in all sorts of booster and spacecraft systems.

I've seen many, many examples of accurate failure mode predictions based on only a few data points (but also based on a firm understanding of the physics of the situation). They ought to bring Mad Don Arabian out of retirement -- he used to do this kind of thing six times before breakfast... *grin*...

-the other Doug

I agree that a nondescript dune field isn't the optimum place for Oppy to become a stationary lander mission. The only thing I guess I'm taking exception to is the comment "We don't know. We're guessing."

Doesn't it make sense that, with an entire failure sequence with which to compare (of identical equipment under similar environmental circumstances), we *do* have the ability to do more than guess? Isn't there a certain amount of engineering rigor to making meaningful projections of the eventual failure of Oppy's wheel based on the observed failure of Spirit's?



-the other Doug

Oh, I'm not saying that the wheel ought to be good for a 20-km trek. I'm just wondering why, at the very outset of a problem that took two Martian years to progress from initial symptom to complete failure on Spirit, we seem to be hearing "Oh, my, will the wheel last long enough for us to get out of Victoria?"

Shouldn't we anticipate that, for example, Oppy ought to be able to putter around Victoria and its annulus for another Martian year or two before its wheel locks in place, rendering her still mobile but much slower and unable to handle steep slopes?

-the other Doug

As with many of the programs on Discovery Science, I have a bit of a problem with the way they have been promoting it.

"See the super-secret Moon program the Soviets never told anyone about -- until now!"

Pardon me, but the world was well aware of the Lunakhod missions at the time. The Soviets trumpeted their successes. In fact, I recall quite clearly during the network coverage of the Apollo 14 landing that the Soviets tossed out a press release as Shepard and Mitchell began their 3+ km trek to and from Cone Crater that Lunakhod 1 had already covered many times that distance in its journeys...

I'm happy to see a decent documentary on the Lunakhods -- but let's please not sell it as some super secret that we're only now finding out about. Let's at least try for a little pravilna...

-the other Doug

I'd just like to toss in the observation that Spirit first showed signs of increased current flow to its failing wheel motor when it arrived at the foot of the Columbia Hills at about Sol 258. By careful handling of her roving, it took nearly a thousand more sols for the wheel to fail, and some of the mileage put on her in between including scrabbling up to the top of Husband Hill.

Just because Oppy is showing signs that her already lightly lame wheel is beginning a slide into failure, is there any real reason to anticipate this failure occurring in a far less number of sols than it did between first symptoms and complete wheel failure on Spirit?

-the other Doug

"Vision On"? Would that be anything like "Carry On, Visioning"?



-the other Doug

I guess I was thinking of the T-Tauri stage, which is supposed to be a pretty intensely hot period, sun-wise. But I suppose that happened earlier on, and is still a controversial theory...?

Seriously, thanks. I actually don't recall where I picked that supposed bit of information. Just goes to show that your brain can lie to you -- don't trust it!

-the other Doug

It occurs to me that the conditions during (and, especially, directly after) the most recent general resurfacing of Mercury could preserve crustal elasticity longer than you might expect. The earliest that resurfacing could have happened would have been right at the end of the LHB, I would think -- the current surface overlays what looks like lunar highland terrain, just covered in thick lava frosting...

IIRC, the Sun was a little hotter three and a half billion years ago than it is now. And Mercury lies so close to the Sun that even a robust outward heat flow would be reversed into an inward flow on Mercury's Sun-facing side.

During the long nights (assuming that Mercury's days weren't all that much different at the end of the LHB than they are now), you'd have outward heat flow and a general cooling of the crust. But the long days could have reversed the heatflow, adding a good percentage of the heat lost during the night back into the crust.

Under such circumstances, the crust could have remained fairly elastic for a rather long period of time, I would think. I'd also think that this might result in a greater degree of crustal differentiation than you see on the Moon or even Mars -- might that explain some of the very dark craters? Pockets of materials that were effectively sorted out of the crust to a certain depth, and then exhumed?

-the other Doug

Exactly. In point of fact, a good number of the well-developed river drainage systems observed on Mars developed in the crests between crater rims in the heavily battered southern hemisphere.

It rained on Mars after the LHB had pretty much breathed its last.

-the other Doug

Back in the Paolo's Plunge thread, someone recently made a statement to the effect that the idea of an early wet, warm Mars has gone from a proposition to a belief. The statement made it clear that this was a bad thing -- that the concept of an early wet, warm Mars is keeping us from seeing how the planet's histopry has actually played out.

I'm responding to that statement here since I don't want to continue to hijack the other thread. But I feel the following two points must be made:

1) Mars was once warm enough (and had a thick enough atmosphere) to support flowing liquid water on its surface.

2) Mars was once wet enough for that liquid water to form well-developed river drainage systems and for enormous floods to scour thousands of square kilometers of its surface.

Those two statements aren't theoretical. Observed landforms verify them with primary, empirical evidence of river channels and catastrophic flood plains.

Those are statements of fact, not belief. My own feeling is that we must proceed from that point and not continually try and postulate a Martian history which cannot account for these proven facts.

Also, to the comment made several times that the LHB was responsible for the stripping of Mars' atmosphere, I must point out that several reputable studies have shown that the interaction between the solar wind and Mars' upper atmosphere is sufficient to have reduced an atmosphere as dense as Earth's to what we see today over the course of three billion years. And that neither Venus nor Earth seem to have had their atmospheres stripped during the LHB.

Just a few points I felt needed to be made at this juncture.

-the other Doug

Except in very rare and extreme circumstances, I visit the forum every single day and spend as much time as it takes to read every new post.

That's right.

Every new post.

-the other Doug

I've seen significant speculation that Mars has tilted on its axis pretty severely over its history, meaning that some portions of the planet that are currently equatorial may once have been located at a pole.

Has a polar deposition origin ever been suggested for the planar layering at Meridiani?

-the other Doug

Victoria shows all the earmarks of having been a primary impact crater -- created by an impact by a meteor, not by ejecta thrown out by another crater somewhere. As such, the impactor was almost definitely entirely vaporized upon impact.

The complete lack of impactor fragments at Barringer Crater proved rather conclusively that impacts of that size and energy always vaporize their impactors, leaving no rock left to study.

-the other Doug

That was a very disturbing day for me. One of the few extremely disturbing days I've had in my life.

What disturbs me more, though, is the fact that the Challenger disaster occurred only 19 years after the Apollo Fire, only 16.5 years after Apollo 11, and only 13 years after Apollo 17.

And in the 22 years since, not one single human being has validated the sacrifice of the Challenger crew by so much as venturing out of low Earth orbit.

To me, that's far more disturbing... *sigh*...

-the other Doug

Exactly, Doc. I recall being challenged over making the same statement.

However (and someone correct me if I'm wrong), I recall reading that the HP rocks were found to be much less friable than the Meridiani rocks, cemented with a much less salty matrix. That data came from the energy required to brush the rocks with the RAT -- and that Spirit's RAT brush made less of a mark into these rocks during brushing than Oppy's RAT does brushing the sulfate rocks at Meridiani.

And, of course, the HP rocks aren't shot throught with concretions (or lapilli, or what-have you) like the Meridiani rocks.

So, IMHO, from various clues I've read about, the HP rocks are quite different, in composition and friability, from the Meridiani rocks.

-the other Doug