The most common theory I've heard in re Mercury is that it encountered one or more "big whack"-sized impacts, but that being so close to the Sun and being intrinsically less massive than Earth or Venus, a majority of the ejected material (including most of Mercury's original crust and mantle) never re-accreted onto the planet.

With only a small percentage left of its original silicate mantle, I can imagine that volcanic processes on Mercury would have resulted in landforms that don't look distinctively volcanic -- especially when compared to bodies such as Earth, Luna or Mars.

For example, let's say that only the densest portion of Mercury's mantle was retained. This, and the crystallization of the outer layers of the remnant mantle to form a new crust, could leave only highly viscous, iron-rich lavas available for subsequent extrusion. And since the new crust formed late in the accretion process, you don't see big pile-ups of lava -- as it extruded onto the already thin crust, the whole thing flattened out and the flow features were made very subtle. Thus the distinctive, low-and-rolling landforms of the intercrater plains.

-the other Doug

The problem with a low-thrust spiral-out from the Earth's orbit is that you spend an extraordinarily large amount of time within the van Allen radiation belts. Even hardened electronics can only take so much of that.

You run the risk of burning out your spacecraft before it gets very far away from Earth.

-the other Doug

And after all, when staring a nuclear Armeggedon right in the eye, it's very important to maintain the purity of our Precious Bodily Fluids...

-the other Doug

"Gentlemen! You can't fight here! This is the War Room!" -President Merkin Muffly

Drat! So did I! Apologies, Alan -- you are definitely one of the *good* ones!



-the other Doug

That comic book ran under the title "Space Family Robinson" until 1965, when "Lost In Space" premiered on CBS. At that point, to take advantage of the free advertising, they changed the name of the comic to match that of the TV show.

And yes, the comic book was much more interesting and scientifically plausible.

I thought I was the only one who remembered "Magnus: Robot Fighter"! You're right, it was an extremely well-written and articulate book, for its time. I can particularly remember an issue which dealt with someone sabotaging the worldwide weather control system, and Magnus had to track down the robotic no-goodniks who were responsible...

I had a few other guilty pleasures in 1960s comic books. One of them was "The Metal Men." Another was a short-length occasional feature called "The Atomic Knights." IIRC, both were DC publications. (I liked the DC titles a lot, was a big Superman, Batman and related titles fan, but I also followed the Marvel universe closely. Comic books were a passion for me as a child.)

As you might imagine, I had a huge collection of well-read comic books by the time I was in my teens. A collection that my parents threw away when I went off to college. They were *very* well-read, and likely wouldn't have been worth all that much to collectors. But, for example, I had a first edition Spiderman, a first edition Fantastic Four and a first edition X-Men, to name but a few. (I started buying them with my allowance when I was six or seven, I think -- in 1961 or 1962. My brother started a couple of years before I did, so our shared collection went back to the late '50s.)

I may have come as close to parenticide as I ever would, before or since, when I found out they had thrown away *all* of my and my brother's comics...

-the other Doug

Let's see -- in order:

nprev: I entirely agree. I grew up in an America that had just been outrageously shown up as no better than second in the world in science and engineering, and I watched that America respond to the challenge by growing a *huge* crop of engineers and scientists.

I then watched that self-same America send a majority of those engineers and scientists onto the dole when we, as a nation, proved we were "Number One" and felt comfortable with our place in the world again.

The message was clear: don't fall for the ruse, don't work hard and become a scientist or engineer, 'cause your country will abandon a lot of you. And your dreams.

And, I have to admit, a lot of the scientists who *do* eke out a living don't make the situation any better when they try to bill themselves as "wizards" who are so much more capable and intelligent than anyone else that they can't be bothered even trying to *discuss* their findings with the common scum people. It seems that for every Carl Sagan and Steve Squyres, you have five or ten other guys out there who, when asked what their work means, start out every attempt at explanation with "Well, of course, you won't *really* be able to understand this, but..."


paxdan: While there are a lot of positives in re webcasting, the fact is that webcasts are the ultimate in narrowcasting. You only see and/or hear them if you already have an interest and have spent some effort to find them.

While an increasing number of people are using the Internet as their primary source of news and information, the vast majority still use TV, radio and even *gasp* newspapers as their primary news/information sources. Those mass-media sources (especially TV and radio) don't require nearly as much work on the part of the individual as using the Internet (at least at present). You just select the channels that make you feel the best about yourself and the world and let them feed you the reality *they* choose to show you.

Unfortunately, it is still very true that Western culture is defined and in a sense created by the mass media. The influence of narrowcasting is increasing, but it's still not nearly as pervasive as mass media are.

So, while narrowcasting is not a bad thing, it's the *mass media* that need to have their standards raised in re science and space reporting. Heck, they need to raise the bar across the board, IMHO, but I don't want to get into *that* discussion here...

I would just like to see the mass media put into place enough real experts in the sciences to fact-check their reporting before tossing out these little gems. Have some kind of evaluation process, independent of the broadcasters -- if a given network, or station, or magazine or newspaper is found to be inaccurate over and above a certain level, it loses some kind of important rating. Or has to run a subtitle or page footer saying "our reporting is only 63% accurate, on average" or somesuch.

If you don't have any consequences for doing a poor job, you just let the least capable amongst us set the bar for everyone. That applies even moreso to the mass media.

Just my $.02...

-the other Doug

What I'd *really* like to do, in re lunar habitats, is find a non-collapsed lava tube somewhere. (They really ought to be there -- the rilles are pretty much all lava tubes whose roofs collapsed aeons ago. To me, that implies there are lava tubes up to a kilometer across that are empty but still intact and roofed over.)

I'd seal off the lava tube and pump it full of air. At that point, your "habitat" could be (initially) as simple as a collection of pup tents and air mattresses on the floor of the pressurized "cave."

Of course, I'd also seal and reinforce the interior walls, roof and floor of the lava tube before installing end walls and airlocks and pressurizing it. You just can't tell how long it would take for air to seep through the megaregolith of the upper lunar crust, making it nearly impossible to keep your habitat full of air.

I guess the real issue would be how smooth the interior of an intact lunar lava tube really is -- if it's rough and twisty, it'll be harder to cover with a sealant (or fill with a snug inflatable structure).

Now, of course, with a big enough lava tube, you could then construct multi-storey buildings and such. But what I *really* want to do is have a large pressurized space to move around in, within the 1/6-G gravity field.

Oh, yeah -- and I want a pair of strap-on wings...

-the other Doug

Not really -- the markings at Gusev are caused primarily by dust devils. There have been *zero* indications of dust devil activity at Meridiani (at least anywhere close to Oppy's landing site).

The dust-devil-track type of markings aren't even the most common type of visible wind streak on Mars. The most common type is a clean-sweep dark trail in the lee of crater rims. Orbital observations have *strongly* indicated that these dark streaks are places where wind turbulence has cleaned off bright dust, leaving the dark streaks.

So, one of the reasons why a lot of people have championed the clean-sweep theory for the streaks coming out of Victoria is that this *would* be most like the known wind processes on Mars.

-the other Doug

The early plans for manned lunar habitats (places where people could live for periods ranging from two weeks, to months, to years) didn't really take into account the radiation hazard. For one thing, the radiation environment on the lunar surface wasn't very well understood, and the risks weren't clearly seen.

In later habitation planning, one of the first large tools to be delivered to any site was going to be a small bulldozer. Every lunar hab module designed after the first landings (that I ever saw, anyway) involved digging a trench, laying the hab module into it, and covering the whole thing over with a minimum of a meter of soil. I think one of the things that tended to derail serious talk of building lunar bases was the conundrum that you first had to fly bulldozers to the Moon...

-the other Doug

There is an original version of the Lost in Space pilot that does not include the Smith character at all. Many portions of it were used in the pilot that eventually aired, but in the original, the Jupiter 2 simply encountered an asteroid field while the crew was in stasis, went out of control, and the Robot (IIRC) awoke the Robinsons. That pilot went on through the crash-landing and the trek ahead of the storms that ended up being used in the third or fourth episode, as aired. The original pilot had an *awful* lot of narration in it that wasn't in the aired version, either.

OK, so I have *way* too much minutae packed into this tiny little brain of mine...

-the other Doug

I will point out that *both* "Lost in Space" themes (first season and second-third season) and the "Time Tunnel" theme (plus many, many other TV show themes) were written by a prolific but under-appreciated composer of the time.

Guy by the name of Johnny Williams.

About a decade later, he changed the "Johnny" to "John," wrote the score to "Star Wars," and embarked on a career that has netted him more Oscars than most men have pairs of underwear...

-the other Doug

To heck with them, Phil... I'LL buy the book, that I can promise.



-the other Doug

Well, that was what I was wondering -- especially since I had seen this post from helvick and was truly mystified with his conclusion:



A sequence of sols that started with a stalled drive means "all seems fine"? I was thinking that the stalled drive might well have prompted some troubleshooting, of which the sol 1116 drive was a part.

For the most part, I've noticed that science obs tend to get put on hold while they're troubleshooting engineering issues. That's what I thought was happening; nice to see I was right...

-the other Doug

For a test flight, it was certainly not a complete failure. They demonstrated a lot of good things, and the test of the first stage seems to have been almost completely successful.

If this was an opreational launch, though, it would have been a complete failure, no matter how well the first stage worked. The paying customer would have had his/her expensive satellite dumped into the ocean. That's the real definition of success or failure -- did you deliver the package where the customer wanted it to go?

As tempting as SpaceX's pricing seems to be, I know that if I had a payload that I really needed to place into orbit, I would definitely wait until the Falcons started flying successfully before I spent any money on them. Then again, I wouldn't buy the first model year of, say, a fuel-cell-powered car or a car with a hydrogen engine, either. I'd wait to see how well they work and what the service and maintenance issues *really* are, not just what the salespeople want me to believe they are...

-the other Doug

What we saw in the video could be caused by a number of things, but nozzle erosion and burn-through is definitely one of them.

We could only see about 30% or so of the entire engine bell. A really small burn-through could have occurred on a part of the nozzle that wasn't immediately visible. And that could have imparted a rolling moment to the stage.

Of course, there are a lot of other things that could have happened. I suppose we'll have to wait and see what SpaceX says about their telemetry and the tale it tells.

-the other Doug

This launch, while impressive, illustrates why launching things into orbit is both risky and expensive. SpaceX is going to have to fly a lot of rockets, and study a fair number of failures, before they figure out all of the little, almost unnoticeable things that will jump out from the shadows and destroy their equipment (and the equipment of their paying customers).

For example, if first stage recontact with the second stage occurred after sep, or if the fairing struck the second stage engine when it was let go, they'll have to revisit all of their simulations and modeling, and add systems to keep these things from happening again. Then they'll have to fly those systems and validate their effectiveness. All of this requires actual test flights -- you obviously can't just rely on your paper models or your computer simulations.

Each test flight is a few million $'s worth of rocket, and you *have* to spend that money to get the bugs out of the hardware, or else you'll lose customer payloads. And soon you won't have any customers. At that point, it doesn't matter how brilliant your designers are or how well funded you were -- you're going to go out of business.

As I said, the whole thing points to some very good reasons why getting into orbit is hard, and why it's expensive. By the time SpaceX spends all of the money needed to have a reliable fleet of boosters, the costs they'll have already incurred will have to be amortized through the price of their services. So, while they may still offer the cheapest way to orbit, it ain't gonna be all *that* cheap, and certainly far more expensive than current estimates...

-the other Doug

I saw the engine bell start to describe small circles against the Earth below, and then my feed died, too. Can't get it back, either.

The expansion nozzle was really glowing bright red, wasn't it? I hope she didn't start to tumble because of nozzle leakage -- that thing looked like it was going to burn through the side at any moment, as irregular as the bright red glow appeared...

-the other Doug

Interesting. I wondered why they went through a detank-and-retank procedure on the fuel tanks. With all the problems they've had getting enough LOX on the island to support launch attempts, I can understand why they *only* half-emptied and refilled the fuel tanks.

-the other Doug

By my figuring, that means the count ought to restart in about five minutes.

-the other Doug

They're recycling to T-16:00 and trying for a launch time of 1:10 (I assume that's GMT). Am I right in my calculation that, on my side of the pond, this would be 9:10 pm EDT, 8:10 CDT, 7:10 MDT and 6:10 PDT?

Also, did anyone hear any detail whatsover as to what caused the abort? Do we have any confidence that the thing won't shut itself down again?

-the other Doug

Yep -- the last thing I heard, here, was "Verify you have no contraints for a recycle," followed by "Verified." Looks like they're gonna try again, here.

-the other Doug

Like I've been saying all along -- I'll believe it when I see it.

So far, I still ain't seen it. Lots of nice smoke and flame, just no rising rocket...

And I swear, about 30 seconds after the engine shut down and they called the abort, I heard one of the controllers' voices on the loop saying an agonized "Oh, God...!"

-the other Doug

I agree that there are likely other (and more dominant) sources of atmospheric methane replenishment than evaporation from standing bodies of liquid.

What we're missing in this discussion, I think, is that we seem to be seeing some evidence of cryovolcanism on Titan. Even though the temperatures involved are low compared to terrestrial conditions, the locations of cryovolcanic activity *must*, it seems to me, represent temperatures that are significantly higher than the surrounding terrain. High enough to push several materials (organics especially) into locally unique sets of phase states.

This all implies a remaining heat source within Titan. (Not necessarily a very hot source, to be sure, but certainly hotter than most of the rest of the surface.) So it's not correct to evaluate evaporation rates based solely on surface insolation. We also have to factor in the heat that still seems to be leaking *out* of Titan, and accept the likelihood that it's coming from a very small percentage of the surface.

Of course, the remnant heat escaping from Titan is probably not escaping evenly from the whole surface. A majority of it is probably coming out from a very small percentage of the surface. And, of course, from there it is thermally moderated by the atmosphere, which makes it hard for us to pinpoint such locations from the outside.

While you can make very valuable models using black body radiative and insolative characteristics, at some point you have to factor in the chaotic and fuzzy reality of the Real World (or, in this case, the Real Titan... )

-the other Doug

My thoughts exactly! Much of the Martian plains look a lot like the American Southwest from above. I can recall flying out to Phoenix and being able to clearly follow the shoreline of the ancient inland sea.

The land tells its tales... all lands tell them. I'm just glad that, in the case of the Martian lands, we're finally listening...

-the other Doug

Don't forget Deja Thoris!

For greatest effect, all such-named rocks ought to be part of an outcrop named Helium, in a larger structure christened Barsoom...

-the other Doug