I also have to go with exogenic. From the closest images of Iapetus thus far, I could swear I've seen images of dark material piled up like drifts along the "back" rims of small craters ("back" in relation to Iapetus' orbital motion vector). If that pattern persists to finer scales, then we'll have our answer...

-the other Doug

Sadly, as well, the outer edges of the ring ansas are also clipped off. That said, it's still an extraordinary image. Thanks!

-the other Doug

I got a dozen years on ya, ya young whipper-snapper!

I turn 52 this coming October 17th... I was born just short of two years before Sputnik 1.

-the other Doug

As I understood it, Almaz was in fact designed to be launched manned, and was redesigned to add a docking port only after the decision was made not to attempt to man-rate the Proton.

The original crew return capsule on the Almaz was eventually used for film recovery from the reconnaissance camera -- but it was indeed originally designed to return the crew, not just film.

-the other Doug

I got a low-end LCD screen more than a year ago, and it's been holding up well. Very good resolution, nice bright image, and while it has some strings of lcd's near the top of the screen burned in a bit from the top edge of the window frames, I can clear that up by powering it down for about 12 hours and it stays decent for quite a while. For only about $200, it's one of my better investments.

-the other Doug

The weather is supposed to break here in Minnesota tomorrow, as well. We've had something like six straight days with highs in the 90s (40 and over for you Europeans), in late August and early September, which is nearly unprecedented in this part of the world, especially for this time of year. But after thunderstorms tonight, we're looking at highs in the 70s and lows in the 50s for the next week.

MUCH better sleeping weather!

-the other Doug

Just in way of clarification...

The Proton cannot place enough mass into a trans-lunar trajectory for a Soyuz/Zond configuration to achieve a lunar orbit. It could place a stripped-down Soyuz (i.e., the Zond configuration), with no orbital module, descent module and service module only, onto a trans-lunar trajectory, but that configuration can't carry enough fuel to burn into lunar orbit, much less back out.

Also, the Proton has never been man-rated. One of the big things that kept the Soviets from trying to one-up America in December of 1968 was the fact that the Proton suffered (and still suffers) from a lot of pogo and a generally rough vibration regime. While you could probably launch a manned vehicle on a Proton and not kill the crew, it's possible you could injure the crew in the attempt. The Russians have never been tempted to launch any of their station modules manned, after all -- the rough ride the Proton offers is one reason for that.

It would be safer to launch a full Soyuz on a regular Soyuz launcher and rendezvous it in LEO with a propulsion stage that could get you into a trans-lunar trajectory, burn you into lunar orbit, and burn you back out. I think you might be able to launch such a stage all by itself on a Proton, and of course, it would have to be launched unmanned.

-the other Doug

Hey, LA isn't the only place that's hot. Here in Minnesota, it's early September and the reading from the outdoor sensor on my indoor/outdoor thermometer right now is 94.1 degrees F.

This is sort of ridiculous for this time of year in Minnesota. I know it's WAY ridiculous in LA, too. But you expect the occasional hot streak in CA going into September. You don't expect it at all here in MN...

-the other Doug

Just for the record, and yes, I'm sure everyone here knows this, but the "correct" way to phrase it would be:

NASA's Apollo program launched seven expeditions with the goal of landing humans on the Moon between July, 1969 and December, 1972. Of these, six succeeded. Two missions each landed on the Moon in 1969, 1971 and 1972. The only mission launched to the Moon in 1970 failed to land.

-the other Doug

Yes, there are some "chain" features on Tethys as well, but it's not as striking as on Rhea, and it always seemed to me that the ones on Tethys were near and generally radial to the big basin.

I also noticed some chain-like features in the only close-up images we have of Iapetus, but again, they're not as ubiquitous as the ones on Rhea. I haven't noticed the same thing at all on Dione or the older portions of Enceladus.

-the other Doug

See, now, I'm beginning to wonder if I'm a ghost and no one sees my posts except for me, LOL... I have been trying to get a discussion going about the linear features and "crater chains" on Rhea for something like a year and a half, if not longer, and not a single person has ever responded to my comments. Now it's ugordan who's noticed these things?

I remember taking images of Rhea and using my primitive image-processing skills and tools to outline the large chains, and then pointing out how these same structures seem to persist all the way down to the smallest visible scales. If I remember right, this was some time in early 2006. I've revisited the topic pretty much every time we get more decent Rhea images. Am I actually going mad and remembering things I never did?

That said... ...I am very, very interested in whether these features are endogenic or exogenic. If endogenic, Rhea becomes an extremely interesting little moon. Even if exogenic, you have to explain how so many crater chains, of all sizes and varieties, show up on this moon while they show up only much more rarely on the other moons of Saturn.

-the other Doug

I understand you're teasing, Brian, but, just for the record...

Dust devils are very specific weather phenomenah. The definition requires the formation of vortical wind structures large and energetic enough to raise surface dust into the air. Dust devils, again by definition, are visible as funnel-like or rope-like structures due to the dust entrained in their vortical structures.

Dust devils do not leave broad fan-like surface markings -- they tend to leave sinuous, worm-like tracks which do not vary in width by more than 20% to 30% along their lengths. The dust streaks emanating from Victoria begin at wind-stricture points along the crater wall and fan out to be several hundred percent wider by the time they fade to invisibility.

Calling every erosional or depositional wind event on Mars a dust devil is like calling any energetic wind event on Earth a tornado. It's an extremely poor, misleading, and just plain incorrect use of the term.

All that said, I'm really not as anal about this as it sounds. I just want to state the case clearly, and hopefully establish a level of terminology use on the forum that maintains us at an "impressively high level."



-the other Doug

I've been saying for many, many months that Rhea exhibits more crater chains than I've ever seen on any other body in the Solar System. It has led me to speculate, here in this very forum, as to whether these chains are controlled exogenically (i.e., actual impact crater chains) or endogenically (i.e., tectonic features/fractures).

Note that the feature you linked to has a very small accompanying feature to the right and below (as this image is oriented). That much smaller feature is parallel to the larger feature. To me, that argues for endogenic control of these features.

I think that the rather large population of such chain features makes Rhea a lot more interesting than most everyone else here thinks.

-the other Doug

At the rate this is going, the Dutchy of Grand Fenwick will be the next sovereign nation to land humans on the Moon...

-the other Doug

Wow -- up to 300 WHrs and we're rejoicing, while at the same time I've been re-reading Squyres' "Roving Mars" and ran across the discussion of Oppy circling Endurance as her first Martian winter approached. The comment is made that she was dropping down to only 500 WHrs in power, which was characterized as "crippling."

My, how we've progressed...

-the other Doug

Unfortunately, most of the pits which may lead into lava tubes are located on the flanks of Tharsis volcanic piles, which are located significantly higher than median. Even if these "caverns" bottomed out a km below the local surface, they would be higher above the median than, say, is the floor of Hellas. So, unless there is some other mechanism concentrating the atmosphere, I can't see how it would be significantly higher in pressure down in these tubes than we see at, say, Meridiani.

-the other Doug

Oh, trust me, I'd be first in line if they were asking for volunteers to go spelunking down into that hole. As far as sense of wonder, and also human-habitable volumes, are concerned, the place is a wonder. And I don't write it off as being *completely* uninteresting from a geological point of view.

But, hey -- if Steve Squyres can write about (paraphrasing here) "nothing but boring, uninteresting chunks of lava as far as the eye can see" about the floor of Gusev, I figure I've at least a little support for the idea that the real action truly is in the much older rocks.

I do admit, though, that Martian caverns would be the perfect places for medium-term and long-term human habitats. Their interiors are protected from solar and cosmic radiation (a very important consideration), and the application of enough heat (plus a little Yankee building ingenuity) could seal up cavern walls and allow a section of a cavern to be pressurized with a livable atmosphere. Heck, with enough native water, you might even be able to make indigenous concrete...

-the other Doug

No. One of the datasets that is most wanting about Mars is its crustal heat flow, both average and regional. Thermal emissions instruments (TES, infrared imagers, etc.) give a rough idea, but what I wouldn't give for a set of 20 or 30 heat flow probes scattered across Mars. I'd *almost* like that more than I'd like a seismic network.

-the other Doug

Also proven by the American Mercury capsule spacecraft. Its reaction control system fuel was H2O2.

-the other Doug

Oh, present company excepted, of course!



-the other Doug

Grrrrooooooaaaaannnnnnn!!!!!!!!!!!!!!

-the other Doug

One more time -- there have never, ever, even once, even just maybe, *ever* been any dust devils spotted anywhere near Opportunity. All of Oppy's cleaning events have come from straight-line winds.

I know I sound like a broken record on this sometimes, but it's like wishing for a nice, refreshing blizzard in the middle of the Sahara, or expecting tornadoes at the South Pole. Some types of weather are just not observed at some locations, and dust devils are just not observed at or near Oppy's landing site.

That said, I have high hopes that the inner slopes of Victoria will intensify local winds (that old racetrack pattern) and that by dipping down into her, Oppy will be able to avail herself of cleaning events regularly.

-the other Doug

You know, it's really interesting and cool to look into such a Martian pit. But, guys -- it's all basalt. Garden-variety basalt. You can look at the exact same kind of rock all over the Earth, and if you want to get some from off-Earth, there's a quadrillion tons more just 400,000 km away...

In other words, while the feature really looks interesting, it doesn't tell the story about Mars that I want to hear. The rock beds I want to see a sharp cut through are a lot older than this stuff.

-the other Doug

It's a grand old tradition in just about every journalistic enterprise, unfortunately. I started out, back in nineteen-mumblety-mumble, as a journalism major and then as a reporter/editor/photographer for a small suburban newspaper chain near Chicago. About 40% of the "news" content of those things consisted of slightly re-written press releases. I spent more time rewriting them than most of the staff, since a vast majority of those who write the press releases have no journalistic training and write extremely poor news stories.

It happens everywhere, from the Oak Brook Press to the New York Times. Trust me.

-the other Doug

Unfortunately, tasp, if the ridge was built up like that you wouldn't see the ramparts along the sides of it, you'd see them building up a bigger and bigger wedge-ramp as you went around the globe. I think.

-the other Doug