My suggestion for trying to maintain a high l/d for as long as possible was simply to give yourself a lot of time to continue to bleed off energy. The longer you can stay up in the air and use it to brake, the less time you'll have to spend using rockets to slow you down.

As for very slow approaches to Mars, Doug is right, terminal velocity on Mars is still so high that you continue to have to address the Mach 5 problem. And if you're taling about landing humans there, you must remember that the greatest hazard in going to Mars is going to be from the interstellar radiation environment. Any long-lasting human settlement on Mars (or the Moon, for that matter) is going to need to cover its hab modules with enough dirt to block energetic cosmic rays, and you'll need to spend as little time as you can possibly manage en route. Otherwise, you'll be condemning your crew to an early death.

So, for human transport, you don't want a slow, leisurely trajectory -- you want the fastest possible trajectory you can manage. And, not incidentally, one that clears the van Allen belts as quickly as possible, spending the least amount of time traversing them as possible.

-the other Doug

Ah, but this assumes that the bureaucracy can agree on an exploration strategy (i.e., a set of goals) upon which to design an architecture.

Are we trying to find signs of extant life on Mars? Are we looking for signs of extinct life (paleofossils, etc.)? Are we trying to gather all of the information needed to support a manned landing? A colony? Do we require the knowledge needed to manufacture consumables and fuels from indigenous sources?

Or do we just want to better constrain our theories of the origin and history of Mars?

I think you'll all agree, the amount of money needed to achieve the goals associated with the various broad-brush strategies I mentioned above vary just as wildly as the strategies.

Anyone care to guess how long it will take for the American government (or any government, for that matter) to agree on, and commit to, any of these strategies? Or how long any government will remain committed to any of them?

Until that happens, scientists and engineers have to keep playing the best games available to get *any* missions designed, developed, built and flown. I can't fault anyone for seeking out any and every means possible to get that done.

When NASA, or ESA, or JAXA, or anyone else can show that they can not only agree on a strategy but stick to such a strategy for more than two or three years at a time, I'll agree with you two. Until then, I suppose we'll just continue along doing things the old-fashioned, chaotic way.

-the other Doug

On the other hand, I can just see a Bob Newhart phone routine coming out of this:

"...and, um... let me get this straight. You're going to hook me up to a balloon? OK. And, and, and... the balloon will take me up above the atmosphere? All right. And, what happens then? The... you say, the balloon breaks? And then... then I fall all the way back to the ground?! Oh, a parachute, OK, I see..."



-the other Doug

As for the new default -- I don't mind the colors (well, OK, the grays) or the formatting. But I really dislike the font it uses to display posts, etc. I vastly prefer the current display font. Is that something you can change or control from your end, Doug?

-the other Doug

I took a good look at the initial HiRISE image of Home Plate, and I see a lot of interesting fractures on this feature:



I apologize for the crude image tools. The red lines follow a number of what appear to me to be fractures. Some of them look like they could be remnants of crater rims, but most (especially those along the left edge of HP, as seen in this image) appear to be constructional fractures.

Some may well be dessicational -- but most, especially those near the perimeter of HP, look constructional to me.

-the other Doug

In re JRehling's suppositions about how the dark material is formed and spreads, and nprev's counter-arguments, and the unchallenged comparison between the (postulated) originally pristinely bright Iapetan surface and the degradation of snow in terrestrial urban environments:

Terrestrial snow doesn't fall as a mixture of bright white snow and black/gray grime. The grime is added to the snow after it has fallen, primarily from automobile effluents.

The grime is exogenous to the snow in the example given.

If Iapetus' leading hemisphere was originally as bright as its trailing hemisphere, and if the dark material that mantles it now is residue from the sublimation of ices out of an ice/dark material mixture, you still must explain how the ices on the leading hemisphere only were admixed with dark material.

I cannot accept the idea that the dark material admixture is coincidentally most strongly concentrated on the moon's leading hemisphere. As in any discussion of real estate, the key to this mystery is... location, location, location!

The dark material landed first and most on the leading hemisphere, and has been spreading back ever since. I don't see any other explanation that makes any sense to me...

-the other Doug

You obviously observe vertical and near-vertical surfaces from a slant angle. Now, as good planetary imaging afficienados, we tend to think of getting the greatest resolution, and the greatest resolution (and most useful angle for projecting our images onto DEMs or using them for mapping) is from directly above.

But especially in the game of reconaissance spacecraft, what you want to look at might not pass directly underneath the resource(s) you have in place. So, you end up working a series of compromises; do you want 15-cm resolution of the ground 112 miles away from what you really need to look at, or do you want 23-cm resolution of what you need to see, at a slant angle of, say, 17 degrees?

And, of course, there are times in the recon biz when you *want* to see things from a slant angle, when you need to analyze an object or a construct in three dimensions. There is only so much you can do to reconstruct something's shape from a direct overhead shot and a short shadow...

-the other Doug

I've always heard that those were just that -- anecdotes. However, from what I've heard, the more recent orbital reconaissance assets are multi-spectral, able to return images in color and in non-visible frequencies.

I've heard that the rumors of being able to read license plates were apocryphal, but that you could, in many cases, determine the issuing state of a given license plate from its unique color combination. You could also determine the rank of a given officer by the color of his shoulderboards (depending on the particular uniform specifications of the government you're observing).

Infrared imaging, of course, has very obvious benefits.

-the other Doug

Ha! My memory is that we saw him walking away from the camera with the diapers in his hand, and he dropped them as he approached the shower stall. Then we cut to him stepping into the shower. This was the only shot from the film I recall that is missing from the piece available on YouTube.

-the other Doug

OK, cool. I like the option of choosing, is all.

As for posting times, I'm beginning to wonder if it might not be a forum-specific thing. It just took 50 seconds for a post to the Icy Moons forum (the poll topic, Iapetus black-on-white or white-on-black) to post, and then adding my vote in that poll took 40 seconds. But posting on this forum takes a second or two only.

Perhaps there is some board-specific setting that is checking for virii and such on some boards, but not on others?

-the other Doug

OK -- I understand your conclusion, here. But I still want to hear your theory for how Iapetus got a dark, reddish natural surface, and from where the bright ices that are covering this dark surface came. If insolation can "burn off" the snow from sun-facing slopes, over billions of years, shouldn't it have burned off ALL of the snow?

Iapetus has no atmosphere, so we're not talking about a hydrocycle, here. If what everyone has been saying is true and it's stone-cold dead, it hasn't vented icy plumes for billions of years. So why hasn't all of the snow been burned off, the vapor sputtered into space?

And, to reiterate -- how did this entire moon get surfaced with a dark reddish material that's different in composition from any of the other icy moons, and yet seems similar in composition to Titan's atmosphere?

Before I can accept the concept that the dark material is the natural surface and the icy snow lies on top of it, I need to hear a mechanism postulated that accounts for this dark surfacing. And just saying "Well, it's probably a KBO, that explains it" doesn't explain a thing for me... show me where KBOs follow a pattern of having dark, reddish surfaces and explain how they *all* got surfaced that way, and maybe I'll start to consider it. But until then, Occam's Razor tells me that any airless icy body that was born anywhere near Saturn ought to have a bright icy surface, and that any significant darkening must be an overlay on top of that icy surface.

-the other Doug

Posting is now back to the normal speed. Must have been a first-day glitch, maybe something to do with how Invision was updating the databases. But it's smoothed out now.

As for changing the default skin, can we have a chance to at least take a look at the choices, like last time? I've gotten used to this skin, and wouldn't care for anything that's more garish.

-the other Doug

Yep -- that's exactly what I remember! Except that this one is edited, it removes about two seconds of Burke walking into the shower.

So, I didn't dream it. Kewl!

-the other Doug

That soon? That's ahead of their schedule, isn't it?



-the other Doug

I'm only noticing one difference in how the new software runs vs. the old software. It seems to take from three to ten times longer for a post to upload and appear now than it did before the upgrade.

I've noticed this from the moment I first made a post this morning, and it still holds true. Even a short post takes 20 to 30 seconds to upload, and a longer post (say seven or eight paragraphs) can take up to two minutes.

Every other operation seems to be very quick and smooth, or else I'd chalk it up to bad connections between here and the servers on the other side of the pond (as happens often enough). But since the rest of the forum operations are as fast as I've ever seen them, I just can't buy that explanation anymore.

It's definitely taking a significantly longer time for posts to actually post. It doesn't bother me overmuch, but it's the one big thing I've noticed in terms of performance.

-the other Doug

During Apollo 11, I watched a little of ABC's and NBC's coverage, but I mostly stayed with CBS News and Walter Cronkite for my immersion in the first lunar landing. And there was a lot of coverage to wallow in -- CBS alone spent more than 32 consecutive hours covering the landing, surface operations, launch, rendezvous and docking phases of the mission.

Now, I know that the BBC spent an awful lot of air time on Apollo 11, as well, and I know from some videotapes I've seen that James Burke, the Beeb's science correspondent at the time, anchored that coverage in the UK.

At some point during one of the more quiet periods, Cronkite actually had a short interview with Burke, comparing notes on how the American and British publics were reacting to this historic event. But what I remember most clearly was a filmed feature segment that Burke had made and that Cronkite ran during this interview.

It started out with Burke fully decked out in a complete, working Apollo lunar surface EMU -- the whole shebang, complete with operating PLSS backpack, radio, visor assembly, overshoes... the works.

As the film progressed, Burke removed the suit, a piece at a time, illustrating what each piece did and how it attached to the suit. Of course, the film was edited -- it showed Burke removing the suit in about six minutes, when it really took him the better part of an hour.

At the end of the film, Burke stripped off the liquid-cooled undergarment, removed the diaper, and marched, stark naked, into the shower. The film ended as we heard the shower turn on and Burke began to sing as he showered. CBS must have run this thing at like 4 a.m., because it was the first time in my memory that American TV ever showed a man's naked bum as the guy walked away from the camera.

Now, I hold Burke almost in awe -- his Connections series are some of the best general science / anthropology works I've ever seen. But I will always remember him first and foremost for this one piece I saw, a single time, in July of 1969.

I know I've asked this before, probably on this very forum. But we have new members, and many of them are from the UK. So, here's the question -- does anyone else remember seeing this film of Burke's lunar spacesuit striptease? And further, does anyone remember Burke's Apollo 11 coverage? I wasn't able to watch it, of course, being stuck in the middle of Illinois at the time. But I'd be curious if any of you Brits who actually remember Apollo 11 could comment on your memories of his work at that time?

Mostly, though, I guess I just want to make sure I didn't dream that whole film that I recall so vividly...

-the other Doug

I'm a re-reader. When I come across a book I truly enjoy (even fiction), I'll re-read it many times. Some books I have read literally hundreds of times since my childhood.

I have read 'Roving Mars' by Steve Squyres probably 10 to 12 times since I got it when it came out a couple of years ago, though I hadn't re-read it in the last year or so. I just re-read it again.

It leaves a very unfinished feeling, reading Steve try to wrap up his book with "Well, gee, here we are at sol 227 for Opportunity and sol 248 for Spirit, and God only knows how few sols we have left." Talking about the incredible longevity the rovers had demonstrated. and how, as much as it would hurt, he would be incredibly proud of everything the MERs had accomplished if they died the next sol.

And here we are, more than a THOUSAND sols later, with two rovers that are, for the most part, still going strong. With untold adventures behind them that Steve could hardly have imagined when he was trying to wrap up their story.

I guess this is a somewhat roundabout way of saying...

I WANT MORE!

We need 'Still Roving Mars,' Steve. And then, when it comes time, 'Roving Mars Far Longer Than Anyone Would Have Believed.' And finally, 'The MER Story, or How We Drove to Join MSL'...

In other words, all kidding aside, it's time not for an extra chapter or two, but a whole second book. Steve doesn't have to do it alone -- there are lots of people who could contribute to follow-on books. But what I want, very specifically, is that "inside look" into the day-to-day operations and science planning that we got from the first book.

Anyone else think it's useless waiting for these little buggers to die before the next book comes out? I mean, I really don't want to wait until 2015 just to get the next thrilling installment...

-the other Doug

Ballute.

the other Doug

Actually, for every one of the twelve humans who landed on the Moon, there was absolutely no sensation of being "in flight" when they were on the surface. As strange as the place was, as cramped as the cabin was, as odd as the low gravity was -- the overriding sensation was of being on the ground. Immobile.

I guess it's the same as any of us. We're "in flight" -- we circle the Sun, we spin along on the surface of a sphere that's rotating at a pretty fair clip, we're dragged along as the Sun flies through space in its galactic orbit, and the whole galaxy is speeding along within the rest of the Cosmos...

And yet, because I'm at the bottom of a gravity well, and because if I set something down in front of me it stays there, and because I can get out of my vehicle and walk across the plains in front of me to see what's over the horizon... for all of these reasons, I'm on the ground.

The same was overwhelmingly true, for all of the men who landed on the Moon, once they had landed. As Pete Conrad once said, he was in no-sweat mode the entire time he was on the surface -- because he wasn't flying.

As for me, though, while I found the lunar liftoffs exciting and a little scary, they never were as big a deal for me as the launches and landings. For one thing, we never got to see the first three real-time, and so there was nothing to see at all (except for some fairly crude animations the networks had put together). And while I was pretty nervous about the first one (since no one had ever even done a fire-in-the-hole separation of the LM's ascent and descent stages before, not even in ground tests), that was the only one I ever really sweated out. (Of course, the LM's descent engine had also never been fired in flight for anything like the 12 minutes of a PDI burn before Apollo 11, either, and for some reason that fact, which I knew at the time, didn't make me at all nervous. Go fig.)

But even with the J missions, when we actually got to see the LMs lift off, it just wasn't the highlight of the surface operations for me. Yeah, it was cool... and somewhat spectacular. But I had great faith in the ascent engines by then, I figured there were so many ways to fire that engine, there just wasn't all that much to worry about.

Maybe one of the things that kept the lunar lift-offs from being all that impressive to me is that, for the ones we could see, they never got the audio synced up with the TV. Because of the converters they had to use to merge the 3-filter color wheel TV system into an NTSC electronic color image, they either had to delay the audio by exactly as much time as the converters delayed the picture (something like 8 seconds) or they had to run out of sync. The NASA feed ran them out of sync for every liftoff, and that somehow always ruined it for me.

-the other Doug

Oh, trust me, I don't seriously believe there was anything like that going on. Just that some peoples' public statements on the general subject could lead the conspiracy-minded to that kind of conclusion.

The lesson, I guess, is that when you go on record as having a given minority view, and you could possibly have some influence on future events surrounding related issues, you have to be more careful than normal to avoid even the appearance of wrongdoing...

But, as I said, I'm not seriously suggesting anyone actually messed up the raws in order to make then unusable by amateurs. Just that the appearance of wrongdoing is invited, and could be pursued by the conspiracy-minded, because some people have aired such views. Actually, on the larger conspiracy front, I'm a little surprised that the Hoaxland crowd never jumped on the image quality issues by screaming "What are they trying to hide?????!!!!!"

-the other Doug

Yep, that's me -- all guts, no glory...

-the other Doug

That is exactly why I put "downwind" in quotes. It's just a convenient way of indicating that I see apparent flow vectors in some of the dark surficial material.

Such a flow could be caused by any number of factors, and I'd be surprised if there is just a single factor controlling it. It could be anything from material creep forced along by interactions with Saturn's magnetotail to atmospheric movements caused by transient atmospheres generated by (relatively) immense amounts of sublimation or outgassing from the leading edge (as has been speculated). Heck, it could just be some odd form of impact ejecta interaction. I will point out that you see some "duning" landforms on other airless bodies, such as the Moon, which are almost definitely formed by ejecta processes. Those are just at much larger scales than you see on Iapetus.

I still think that those who dismiss the dark material as simply "the natural surface of Iapetus below the bright ice" are missing the point. This dark material is unlike any other surficial material on any other Saturnian moon -- Hyperion included. These bodies are made up primarily of ices. You'd have to postulate some mechanism that would first emplace a dark surface on Iapetus before you can start to speculate that the dark material is simply that surface with an overlay of clean ice removed from the leading edge. Having heard absolutely no such theory about the emplacement of a surface that is significantly darker (and of a significantly different composition) than we see on *any* other moon in the system, seeing this dark material having been moved along the leading edge in apparent flow patterns, and seeing a "true" bright ice surface exposed by impact from under the dark surface in many areas, I simply have to regard the possibility of the dark surface being Iapetus' "natural" surface as the least likely of all of the theories.

So, all of my observations and an application of Occam's razor leads me to the conclusion that the dark material is emplaced on top of a bright, icy surface that is far more representative of what we see on the rest of the icy moons. Hence my conclusion that we're seeing black on white and not vice-versa.

-the other Doug

You also have to wonder whether or not the whole fiasco was indeed a simple error. After all, we know that many people on the Cassini imaging team have been less than happy about feeling "forced" to release real-time images.

I'm not a big fan of paranoid speculation, truly... but I can just see a few specific people snickering to themselves and gloating, "Just let those &^%#@! UMSFer's try and scoop us to our pretty processed images with THIS stuff!"



-the other Doug

Exactly, Nick. A lifting body generates relatively little lift even in Earth's thick atmosphere -- relative to big wings with a lot of surface area, anyway. Lifting bodies that have been tested here tend to land at uncomfortably high speeds because they have to be moving quite fast in order to generate enough lift to keep them from dropping like a brick.

On Mars, a lifting body would start dropping far faster than lift can keep it aloft well over Mach 1, I would think. Nope, you need really big wings on Mars to stay in the air and bleed off energy until you can land at a relatively safe, slow speed. And, of course, with no runways paved onto the surface, you're going to be limited to landings in places where there aren't very many rocks or craters -- places like Meridiani. Which are pretty rare on Mars.

-the other Doug

My first reaction to that statement was "Gods, that's another 500 sols!" My second reaction to it is "Gee -- only another 500 sols?"



-the other Doug