How could you know, Jason? If the links are there and active, it's not your fault for thinking that the release has occurred. It's a natural, almost inescapable conclusion.

-the other Doug

Methinks Jason has been watching South Park again...

-the other Kyle

And here's a few more to add to nprev's:

3) What happens if the rover touches down before the belaying lanyards have been fully extended? Especially what happens if one wheel of the rover hits a decent-sized rock before the lanyards have been fully extended?

4) Is the cable/lanyard separation accomplished via a signal in the lander (i.e., a contact sensor of some kind), or in the crane (a slack cable signal)? If it's a slack cable signal, can we be certain that any unexpected buffetting encountered by the rover won't accidentally set it off?

5) Are we certain there won't be enough engine blowback from the surface to set the rover into motion, perhaps so much motion it will tip over at wheels-down? Has the landing-on-a-slope case been considered in this regard, where a given slope (or even badly placed rock) could reflect engine exhaust in such a way as to destabilize the rover?

6) Has the general issue of slopes been addressed? What happens if the rover has a small but significant sideways motion at touchdown (due to substantial winds, I would guess) and that direction just happens to be downslope -- of a significant slope (like 20 degrees or more)?

7) Will MSL's obstacle avoidance capability be able to recognize slopes (hills and craters) as well as blocks?

OK -- I think that's enough for now -- . Thanks for being willing to address some of these questions, Rob!

-the other Doug

You trust? EC -- I find your lack of faith disturbing...

-the other Doug

Excellent work, Phil! I am more and more impressed with your abilities.

-the other Doug

Poor Dawn just can't seem to catch a break.

Hopefully, she's getting all of her problems out of the way on the ground. One in flight, we can hope that everything will be 100% nominal.

-the other Doug

Not if there is seriously rugged lunar-highland-type terrain underlying the Meridiani unit. I could easily see an average 800 meter depth dropping down to 50 meters or less where rims of large (Gusev-sized or larger) craters underlie the Meridiani unit. Since we have no clue as to what underlies the unit, and can only guess at its average depth, a significantly large-cratered subfloor could exist that we can't even speculate about.

Such a feature could offer windows to the subfloor that are close enough to the surface to be excavated. I can't prove this, of course, but *something* caused the large swale that forms the hill on whose gentle slope Victoria lies. I can think of worse explanations for this swale than the Meridiani unit compressing down onto the raised rim of a 60-km crater which lies beneath the unit.

-the other Doug

I assume you weren't aware of that pun -- considering we're discussing how to bury power cables -- or else I would have to kill you...

-the other Doug

As long as MSL has a laser and not an ACME disintegrating gun, we're OK. We all know that when you pull the trigger of an ACME disintegrating gun -- it disintegrates!



-the other Doug

Much of the southern hemisphere of Mars resembles the Gusev region, with the exception of the fact that Gusev was flooded with basalt during the creation of the Tharsis bulge. I would imagine that much of the "lunar highland" terrain on Mars will look rather similar to the Columbia Hills in general composition.

What I want to know is what the strata beneath the sandstone and evaporite at Meridiani looks like, and what the very first strata of those sandstones and evaporites which lie along the contact between the two looks like. That's where a thorough analysis of the Lump might be useful, but as I've said, I think we've seen most of the data we can get from Oppy out of the Lump, since we've viewed it with every Pancam filter and mini-TES and have run each of the IDD instruments on nearby cobbles which seem to represent the same material. We would have to be able to physically move and cut into the Lump to get more details from it, and Oppy just ain't equipped for that...

-the other Doug

First, if the power cables are manufactured on Earth and taken whole to the Moon (which will happen for quite some time to come), then they'll probably have some type of organic-material insulation, such as plastic or rubber. In the future, when we're making aluminum power cables from lunar resources, I'd imagine we'll find a way of making insulation from the silicate slag that's left over from smelting the rocks.

I also think they will probably bury the cables to avoid interference from the lunar radiation environment. Yes, they'll have an up-and-down path, since you can't go more than a few meters on the Moon without running into a crater of some size, and they'll skirt larger (10+ meter) craters. But I can vey easily see a vehicle fitted with a trencher that digs a trench, lays the cable into it, and covers it over in one smooth operation. I think you could probably lay cable no more than 20 to 30 cm below the surface and it will be well insulated from the lunar radiation environment.

EDIT: I will point out that the ALSEP stations endured several powerful solar flares and none encountered serious issues from power surges in their power or data cables. So, while it's something to take into account, the radiation environment may not be as much of a problem as we might think.

-the other Doug

You're probably right -- heck, I would have been good with the MERs being officially named Duck Dodgers and Marvin!

I would really rather see the project managers name the vehicles, just as the crews were allowed to name their vehicles during Mercury and Apollo. After all, what's the worst that ever came out of that? Charlie Brown, Snoopy and Casper? Those names caught the public's imagination, regardless of how silly they might have sounded to some self-important bean counter.

I doubt they'll give a separate name to the descent stage, though. You don't name something that you're going to just let crash... and yes, I know they deliberately crashed the LM ascent stages. But those were going to be named, no matter what. They never named the third stages that they crashed into the Moon, after all...

-the other Doug

One good thing to remember is that the Moon's original crust is made up primarily of aluminum. You won't do this at the beginning, of course, but eventually you will be able to use the anorthositic rocks to refine aluminum in situ -- and then a building boom can truly begin.

-the other Doug

The physics that describes the formation of our Moon from such an impact implies that the impactor must have been completely destroyed. Its core actually merged with that of Earth's -- though I sometimes wonder if that process didn't leave a relative enrichment of heavy metals in our crust.

The impact did more than just strip off some of Earth's crust -- it completely destabilized the Earth, to such an extent that another body's molten core was able to sink and become incorporated into our own. That right there implies a complete reworking of Earth's structure, including crust, mantle and core, as well as the complete destruction of the impactor. The Moon was made up of a very minor fraction of the proto-Earth and of the impactor; its mass is very much smaller than ours. It's important to remember, too, that the proto-Earth that was struck was significantly less massive that our current planet -- the end result embodies most of the mass of a Mars-sized impactor as well as most of the mass of the proto-Earth.

Had the impactor hit more squarely (the angular momentum of the Earth-Moon system implies that the impact was at a very shallow angle), the Earth and impactor would *both* have been totally disintegrated and then re-accreted. You can think of what *did* happen as very close to that -- we re-accreted around a fairly large core remnant.

-the other Doug

I have absolutely no explanation for Mars' dichotomy... I only know that its northern hemisphere must have once looked like its southern. That's purely Occam's razor. I'm also convinced that a very similar megabrecciated surface lies below the immense pile of basalt that makes up the Tharsis bulge.

My image is of a Mars that looked very much like its southern hemisphere, all over, at about 4 gya ago -- roughly at the end of the LHB. (You know, sometime in a range between 4.2 and 3.5 gya in the past). At that point, massive resurfacing began in the northern hemisphere, but far less occurred in the southern. And then, after most of the northern resurfacing was completed, the Tharsis complex began to puke the guts of the still-molten mantle all over the surface. That Tharsis volcanism was likely the last major resurfacing process on Mars.

The Lump may give us a good insight on what the northern resurfacing was all about -- at least give us some first clues. (Yes, I know Meridiani is actually south of the equator, but the dichotomy isn't precisly aligned -- some of the southern cratered "lunar highland" terrain extends north of the equator, and some of the smoothed northern plains extend south.) If the Lump actually does embody a contact between the dry pre-water surface and the surface emplaced by the same processes that shaped what we now see in the north, it's a very interesting thing to investigate closely.

Unfortunately, we don't have the tools we would need to get the kinds of answers out of the Lump that would really provide serious insights. But we're doing well to get every scrap of data that Oppy can collect. I look forward to seeing the papers and theories of the professionals who are guiding this data collection.

-the other Doug

I'm of two minds on the Lump, Tom. The loose clasts sitting on the right side of the rock (as seen in your image) really do look like brecciated clasts that have eroded out of their original matrix. But the major mass of the Lump itself appears to be finely layered, a la the evaporitic pavement we see everywhere here at Meridiani.

If I had to make a guess that would account for both of these observations, I might guess that the Lump was excavated from the deepest portion of the crater and represents the boundary between the brecciated megaregolith (which existed before the sandstones and evaporite were emplaced on top if it) and the rock that was created by the sand/playa/shallow sea environment that came after. So it's possible, perhaps likely, that the stuff we're seeing which shows strikingly different composition from the surrounding rock actually comes from the surface that pre-dated water here.

I have a general concept of a Mars which endured the Late Heavy Bombardment and ended up with a surface rather similar to that of our Moon -- its original crust shocked and shattered to a significant depth -- and *then* was selectively covered with water and carved by both water and wind for several hundred million years before the air thinned and the water froze out. The southern hemisphere still shows large stretches of the surface, close to how it appeared just after the LHB ended, craters upon craters reminiscent of the lunar highlands. But the northern hemisphere was more greatly weathered and smoothed, burying the LHB-generated lunar-highlands-type of surface and masking its origins. But beneath the water-borne sediments and wind-blown sands, there lies a brecciated layer of original Martian crust. I have some hopes that, just maybe, the Lump represents some of this material.

Anyone have any of the results of the analyses they did of the apparently similar-looking cobbles lying around? Just what are we looking at here -- basalt? Olivine? Pyroxene? Or something else?

-the other Doug

Actually, my understanding is that one reason for setting up an outpost at Shackleton is precisely because there are locations along the rim which get sunlight most of the time. Which means they *can* erect a solar panel farm up in the permanently sunlit potion of the rim that will power the outpost and any water mining installations.

I'm pretty sure they'll need to simply run power lines and not use transmitted power of any kind (including reflected sunlight), since they will need to power installations in the adjacent permanently shadowed lands just inside the rim. Beaming microwaves or concentrating sunlight would have the tendency to drive the volatiles out of the adjacent soils -- and our engineering isn't good enough to prevent significant energy leaks along the borders of beamed power routings. We don't want to boil the volatiles into space, we want to gather and use them!

-the other Doug

Jim, I think the suggestion is that the descent stage *could* be programmed to right itself and lower itself gently. It has to have *some* amount of control function in it, since it has to indepedently maneuver itself away from the rover after it cuts the cables.

I wonder just how much mass might be available for a very small science package and a small transmitter that would relay meteorological and/or seismic data back to the rover, and thence through MRO back to Earth? You'd need some light, simple instruments, a small transmitter and a small antenna. How much would that weigh? And how much mass could MSL stand to be added to the overall package?

I don't think anyone really believes that such a capability will seriously be considered, but it's OK to at least think about it...

-the other Doug

You'd best be wearing Pirate regalia when you say that, fella!

-the other Doug

Without you guys, John, we wouldn't have anything to be excited about.

For a "lucky happenstance" encounter sequence, your spacecraft absolutely kicked butt! Kudos go to everyone on the NH team -- even that minority who aren't regular posting members of our UMSF family!

Good luck and Godspeed.

-the other Doug

Be good, Doug... Be good, Doug... (Clarifying edit to Our Fearless Leader -- I'm talking to myself here... )

Phil, my understanding is that once the transportation system is in place, one out of every three or four manned landings will be sortie missions that will land at various locations to do some true exploration. A majority of the work at the polar outpost will be to pioneer the engineering techniques required for humans to survive on a planetary surface other than Earth's for extended periods.

At least, that's the current plan. No one has any idea what's going to happen after the current administration leaves office -- even a new Republican administration may abandon the lunar mission plans, since there has been precious little spent yet on the LSAM and Ares V systems. I still think the most likely thing that will happen will be that the LEO version of the Orion will be developed, and everything else will get put on hold indefinitely.

But, please, hear me now -- engineering research is still scientific research. It may not be the kind of science you're interested in, but it is most definitely scientific research. Please don't disdain applications science in favor of research science -- there is a place and a need for both. Recall that MPF was an engineering demonstration mission, the science package was almost an afterthought. And without MPF's demonstration that the airbag landing system was a sound one, we would not have two rovers on Mars right now.

-the other Doug

Oh, I'm positive he is, Emily, and I mean no disrespect, Rob. Maybe it's simply that you have that "lumberjack" look that makes one think of blue jeans and flannel shirts... in any event, I really can't remember where I got that impression from. I couldn't cite you a particular time or image in which I've seen you wearing that. It's just always how I picture you when I read your posts, here.

-the other Doug

And don't forget a flannel shirt, Alex. For some reason, I always imagine Rob wearing blue jeans and a flannel shirt...

-the other Doug

Yeah -- like I say, *if* HiRISE imagery shows there is a relatively clear path through the northeastern apron of Victoria back up to the "tarmac," as you put it (as good a name as any), and *if* there are no major drive-around obstacles along the route to A-B-C, at an average of 200 meters per sol driving, it would only take 100 driving sols to cover 20 km. And I'm not even positive that A-B-C is as far as 20 km, that complex may only be 12 to 15 km away.

While that kind of traverse would have seemed like a completely unreasonable goal at the beginning of the mission, we know now that, if we choose, we *can* drive an average of 200 km per sol for extended periods. And heck, even if Oppy adopted the drive-three-survey-one sol plan used by Spirit on its way to the Columbia Hills, it ought not take more than 150 sols, max, to get from Victoria to A. Perhaps as little as 100 to 125.

I'm not too worried about it at present, since we're probably looking at spending the entire Martian summer and fall at Victoria. But for a long-term plan, I think that any traverse plan that places us back on the tarmac stands a good chance of getting us to another interesting location before winter solstice.

I'd be far more comfortable with an extended mission plan that gets us to a new set of interesting targets before winter solstice, than with a plan that calls for us to just sit at Victoria for the entirety of the next winter -- assuming we're done with Victoria by then. And I have to agree with Doug, I just don't see a clear straight path to Ithaca from Victoria.

And, of course, we have to understand that Oppy could die, become sensor-crippled or become hobbled at almost any time. I will rather diffidently make the point that if we lose Oppy's IDD in the midst of the Victoria campaign (and the IDD is the logical item to be lost next, since it is the most degraded of any of Oppy's sensing equipment up to now), it will take considerably less time to gather as much information as possible from Vicky and it may make more sense to observe what we can of other interesting targets before anything else dies, and especially before she completely loses a wheel and becomes hobbled like her sister. Without the IDD, you only have Pancam and mini-TES for detailed scientific analyses, and it will take far less time to gather that data than will be taken deploying the arm and running week-long Mossbauer and APXS integrations.

But, of course, we *will* have to get some decent HiRISE coverage of the whole area before we can do more than engage in energetic arm-waving...

-the other Doug

Exactly -- as Doug says, we need more HiRISE images of the entire area. I'm sure that a complete survey of the entire area is in the plans, since applying the ground truth we have from Oppy to the entire area is important in understanding the formation processes of the region, and HiRISE images are so good that they let us make some pretty high-order connections between where Oppy has been and the rest of the area. But it will probably be a good, long time (months, at least) before MRO captures all the data we want. (And remember, we'll probably want CRISM coverage of the area too, to help determine where we might find interesting minerology.)

The more I look at the area to the east-northeast, the more I like the idea of heading that way. If the terrain is as good as it looks, with 200+ meter drives you could reach the area of the A-B-C craters in as little as 100 sols of driving, as opposed to the probable 600 to 800 sols of driving needed to travel the same distance through etched terrain. And to top it off, once you finish with A-B-C (and possibly another sinkhole-like feature I'm thinking of as D, located to the west-southwest of A-B-C), there is what appears to be a straight shot on good terrain directly south to the area of Ithaca, so if Oppy is still working and you really wanted to, you could still get to Ithaca -- while getting more science in and possibly taking less time than if you took the more direct southeast route.

Now if I could only mention my ideas to the MER team... I'm pretty sure, though, that if I, an interested amateur, sees these things, *someone* on the MER team has to have seen the same things and come to the same conclusions.

Fingers and toes crossed...

-the other Doug

p.s. -- if anyone has any good ideas for designations of A, B and C, even though we know they'll be preliminary and not adopted by the official MER team, I'd be more than happy. It gets a little bland to continue to refer to these very interesting targets by simple one-letter designations. And the best I've come up with is Moe, Larry and Curly, with the unlabeled D standing in as Shemp...