So, here's a question -- is the download rate limited more by intrinsic limits on data transfer rates (i.e., the spacecraft's transmitter power and the size of its dish), or by the relatively short periods of time you have the Cerberus facility available to receive downlink? (I know you have some attitude issues which result from VEX being designed to orbit Mars and not Venus, but I'm looking for average data transfer rates, here, not those that are constrained by other parameters.)

What I'm getting at, here, is whether or not a vastly expanded Deep Space Network would aid appreciably in getting more data off of the vehicle, thereby letting you take as much data as the instruments can actually collect.

I hate to see a valuable resource being under-utilized because of bottlenecks in our ability to get data back from it. And I'm wondering if it just isn't time for an expanded DSN to be started. If it could be funded by an international consortium that gets its seed money from something other than charging rapacious hourly rates, that would be even better... but I keep hearing more and more issues with the ability to get data back from our spacecraft that are out there exploring the unknown, and it just seems bass-ackwards to spend billions of dollars on a well-designed probe and then hamstring its science return because we have an antiquated DSN that can't keep up with demand and yet still charges thousands of dollars (or Euros, or what-have-you) an hour for the privilege of using it.

Maybe we ought to have everyone convert their unused Dish Network dishes into a vast distributed amateur Deep Space Network and offer its services to all comers, first-come-first-serve...?

-the other Doug

There are several costs in keeping the MERs active and operating. The largest cost is probably the staff of engineers, controllers and scientists who determine what the rovers do on a day-to-day basis, but there are other, not-insignificant costs, such as:

DSN time -- probably the largest non-payroll cost, using the DSN to communicate with the rovers (or, more specifically, to communicate with Odyssey as it relays to and from the rovers) costs somewhere in the thousands of dollars per hour, IIRC.

engineering support equipment -- specifically, there are the ground models of the MERs that are used to simulate various previously-untried activities. They used these ground models (one of which is nothing but the drive system, I know) to figure out how to safely drive on steep slopes, and how to get unstuck from killer rover-trap dunes. The equipment has to be maintained, and people who are only tangentially involved in MER operations have to be retained to operate this equipment.

Mars yard -- JPL, as far as I know, still maintains a Mars yard in which various MER operations are rehearsed. That also takes resources and manpower to configure and use. Yes, they at JPL have created a new, larger Mars yard for MSL rehearsals and study, but I believe the old one is still being used for MER operations.

While the per-sol costs of the MERs drops steadily as time goes on, because by far the greatest costs of the mission were in spacecraft design & assembly and booster procurement and we're now simply amortizing the costs over a longer and longer time frame, there are still real costs that will continue as long as the MERs keep operating.

All of that said, the incremental costs of keeping the MERs running are worth it, I think, as long as at least one of them remains mobile. The fate of mission extensions after a major failure really depends on what type of failure occurs. For example, if Oppy loses the ability to deploy its IDD but is otherwise in good shape, I imagine there will be mission extensions until something else fails. But if both rovers become immobile, you *may* see them shut down after they examine their near fields as thoroughly as possible.

-the other Doug

You don't really gain all that much by using a direct trajectory. A little, yes (and I'm not up for doing the math at the moment), but not a huge amount.

The problem with the idea is that the Ares V doesn't have the lifting capacity for a decent-sized mission module (like the LSAM) *and* and Orion spacecraft. Trying to lift the whole stack, LSAM and Orion CSM, into a lunar trajectory (whether or not you use a parking orbit) is just beyond the capacity of the Ares V, as currently envisioned.

The only way to get a full, manned Orion/LSAM stack to the Moon with the boosters currently planned is to launch each separately and dock in LEO before heading out... it's a basic limitation of the system.

-the other Doug

Now, opening up the Rocky and Bullwinkle universe for naming gives you *tons* of possibilities.

For example -- for a pair of spacecraft, Boris and Natasha would work quite well. For a single spacecraft, you could anything from Peter Peachfuzz to Fearless Leader -- or even the enigmatic "J." And, of course, a high-latitude landing site would be Frostbite Falls.

And what would the mission be? Well, it's obvious -- "Follow the Upsydasium!"



-the other Doug

"Hey, Rocky -- watch me pull phyllosilicate clays out of my hat!"

It will only be given a name like *that* if they give the naming rights to Monty Python...

-the other Doug

edit -- serves me right for responding to a post at the bottom of a page before looking at the next page...

That makes sense, Don -- though IIRC, isn't there a large, heavily eroded caldera structure in the middle of Meridiani Terra, which (in global terms) lies adjacent to Meridiani Planum? Could be a source of volcaniclastic materials in the Meridiani Planum area, could it not?

I'm still interested in how you explain the finely layered nature of the rocks seen at Oppy's landing site (and, by inference, the entire 800m thick Meridiani unit). And I'd love to see computer simulations of the turbulence at the surge/ground contact...

-the other Doug

And nothin' says lovin' like somethin' from the oven...

-the other Doug

I would actually prefer MSL be named after a ship that engaged in a great voyage of exploration. I know we're running through those names at a fast clip with the Meridiani crater naming conventions, but there still ought to be some left that would work.

Heck, if you don't mind re-using names, there's always 'Challenger'... and 'Beagle' would be nice, if ESA could be convinced not to pitch a fit about it...

-the other Doug

Yes -- I brought up the finely layered nature of the rocks at Meridiani before, and that question was never addressed by the Professor. I can see these rocks being built up by aeolian deposition of millimeter-deep layers over the course of tens of thousands of years, laid down on wet ground (and possibly onto shallow standing water), far more than I can see tens of thousands of base surges, each laying down a very thin, very flat layer of rock of consistent composition to the last base surge, each laying down a very flat, very thin layer with almost no turbulence developing along the surge/ground contact.

Such surges would, I would think, have enough energy in them that we would see scouring and channeling -- the very same types of landforms whose lack that the Professor cites as a disproof of standing water or a playa environment. If these layers were laid down by an energetic base surge, how can they be so overwhelmingly flat, with very little sign of any turbulence? (Remember, the cross-bedding we've seen is the exception, not the rule, in these rocks.) Are you postulating that there were *no* surface features that would have caused turbulence in the surge/ground contact? (We may not be able to watch and observe a surge in detail, but we have a ton of similar surge-emplaced landforms that we have observed in great detail on the Moon, and even with a lack of atmosphere, we see evidence of a fantastic amount of turbulence in the debris flows that generated terrain on Luna.)

I also have a difficult time understanding how these deposits could have been laid down at the end of the Late Heavy Bombardment. There is visual evidence supporting the theory that the rough, cratered terrain generated by the LHB actually underlies the Meridiani deposits. You'd have to assume, based on the range of crater-like landforms, the relative lack of large craters, and the relative flatness of the terrain, that the nearly kilometer of Meridiani deposits were laid *after* the LHB had finished. In other words, if the Meridiani unit was generated by tens of thousands of impacts at the end of the LHB, why would the unit not have been broken up by these impacts as quickly as the base surges laid it down? What makes Meridiani so special that it could be laid down by impacts all around it but not suffer any impacts in the area itself, thus leaving this layered unit (which would have required millions of years of base surges to lay down) mostly intact?

Occam's razor suggests that we're seeing an entire population of dead grandmothers here...

-the other Doug

OMG! I haven't played that particular drinking game in 30 yers! (I believe, at the time I learned it, that 'Beterman' hadn't codified it yet -- it was simply known to me as "Zoom-Schwartz-Profigliano-Zoom.") I learned that game in my junior year of college (otherwise known as the Great Sodden Semester... )

I totally agree in terms of developing models, even on insufficient data, Mike. It is often the process of building a model that shows you what's not consistent with your base assumptions, and sends you out looking for data to confirm or deny certain of those base assumptions. It is perhaps possible to learn more by simply going out and collecting every scrap of data that you possibly can, but we all know that data-collection schemes (and the sensors used to collect the data) are so specialized these days that you have to triage -- you have to decide in advance what kind of data you're going to collect in any given scheme (read: any given mission).

For that task, you need a model and you need a set of base assumptions that you want to test. Without that, you can end up either getting tantalizing hints of things you just didn't have the tools to investigate or, worse, you miss something extraordinary that you could have seen if you had flown the proper types of sensors.

-the other Doug

Ummm... if the Tharsis shield volcanoes and dozens of other classic calderas readily observed on Mars aren't volcanoes, and if the very clear and obvious lava flows (which read as basalt from both surface and orbital spectral analysis) aren't volcanic, then what are they?

I hate to say this, but if your theories are based even a little tiny bit on this "observation" that Mars is "missing volcanoes," then you do seem to be ignoring empirical data (labeling it "theoretical") that doesn't fit with your own theories, and that's when the scientific method fails.

I'm sorry -- I simply *must* have misinterpreted what you mean, here, since that statement is so obviously false.

-the other Doug

Well, think of it this way -- a MER is about the size of a golf cart. MSL will be about the size of a Jeep. No wonder they want to find a way to just gently drop the thing onto its wheels and not have to worry about a platform big enough for it to roll off of...

-the other Doug

-the other Doug

Yeah -- you can see she's cleaner than she was, but it wasn't a full cleaning event. The panels near the ends of the wings are still pretty dirty.

Still, any cleaning whatsoever at this point is a gift, and I accept it gladly...

-the other Doug

Oh, I imagine the nail polish would work fine on Mars. The toes themselves, of course, would puff up and start bleeding from underneath the nails... but the polish would survive just fine.



-the other Doug

The answer to your question, Steve, is yes.

The truss itself is basically complete. The "narrowing" is actually the transition into the alpha rotary joints that allow the arrays to be steered, always presenting the largest surface area to the sun. While the joints appear to be extensions of the truss (and are, for all practical purposes), they're actually located outboard of the truss ends. (The truss, BTW, is the largest structure ever assembled on orbit.)

And yes, the "rail cart" tracks only run the length of the actual truss and do not extend out onto the rotary joints.

-the other Doug

Boy, Stu -- if that's the case, I'm sure glad they didn't name it Gator Bay!



-the other Doug

They have three of the four large solar array units on orbit, now, though one is retracted for the moment. I'm assuming there are center of mass issues with placing the first unit (I think it's P5-P6) in its final location before the fourth unit comes up next year. And it can't be deployed from its current location, since it would interfere with the movement of the P3-P4 and S3-S4 units.

But think of it -- after only one more solar array delivery flight, ISS will have its entire solar array system up, deployed and in final configuration. And will, in one swell foop, increase in peak brightness as seen from the ground to pretty much the maximum it'll ever have.

-the other Doug

Welcome! I trust you'll enjoy the accommodations...

Don't worry about not being a professional geologist or engineer; most of us here aren't, either. But if there is one best place on the web to learn about these subjects, it's here. I've learned a tremendous amount from the people here, and if I don't thank them often enough, it's just because I'm too busy soaking up even more.

Have fun!

-the other Doug

Michael, I think the pans work well conceptually. The problem Pando had (and I had to a lesser extent) is that your panning isn't following a natural eye-scan process. When we, as humans, stop and take in a scene, we actually move somewhat quickly from one interesting point to the next. If you sped up the movement from, say, ground to horizon, or from far wall to nearby cape, and then lingered on quick zoom-ins of interesting points, it would follow the pattern of human scene-scanning a little more closely.

Also, people have consistent patterns as to how they scan their visual scene. In most western cultures, we start scanning a scene from the upper left to the lower right, and our "hot spot" (where, interesting points notwithstanding, the eye tends to gravitate towards) lies about two-thirds of the way up from the bottom of any natural framing. (If you analyze how the eye scans a page of text, for example, it starts at the upper left, scans down diagonally to the lower right, and then bounces back to a point centered side-to-side and about two-thirds of the way up from the bottom. You can apply this general pattern to most naturally-occurring visual frames.)

Part of the reason western cultures use this large-scale scan pattern is due to the way in which written language is formatted on a page. Many oriental cultures scan their visual scene somewhat differently. But we all share the pattern of jumping from one interest-point to another and letting our peripheral vision fill in the "background."

-the other Doug

I will also point out, in regards re-using the MER design, that while a "quiet" Mars can support a solar-powered rover for multiple Martian years, a single global dust storm could easily kill them. And such global dust storms aren't only possible, they're inevitable. We've been somewhat lucky that the MERs have been operating under optimum dust conditions, overall. Even the small dust storms that have popped up have managed to avoid directly impacting either landing site.

I'm just saying that even though the MERs have lasted a very long time, don't make the mistake of assuming you can re-fly the same (or similar) design and be assured two or three Martian years of lifetime. The baseline mission of a MER rover is 90 sols, and even with an upgrade, I don't see that changing a whole lot...

-the other Doug

Oh, believe me, I'm grateful for the Professor in bringing up the impact surge theory. Impacts have shaped the surface of Mars moreso than they have of Earth, and any geological analysis that doesn't take that into account is ignoring a bunch of 800-lb gorillas in the room, so to speak.

As for the lack of braided channels in the layers we can see -- that bothers me, too. Always has. I wonder a bit about the movement of water in a lower-gravity environment, and whether or not this could have an effect on channeling in shallow water. But when I look at various images of Meridiani, I do see evidence of mud-cracking-type features (such as Anatolia).

Taking everything altogether, Occam's Razor points at water, to me. But I seriously appreciate the concept of alteration by impact processes, since such processes *must* have been occurring throughout the formation of these units.

-the other Doug

My wonderment with the impact surge theory is how it resulted in the finely layered rocks we've been calling evaporite. That would require, through the 800 meters estimated thickness of the unit, tens of thousands (if not more) separate impact surges, would it not? Each one depositing a millimeter-thick layer with only occasional cross-bedding? And the variations in chlorine and bromine -- those are excellently explained by hydrodynamics. How does impact surge theory explain them?

I see tens of thousands of dead grandmothers lurking here...

-the other Doug

Oh, yes, and I forgot to add: Above 600 Whr!!!! Hallelujah!!!!!!

-the other Doug

When you look at the rocks in specific and the surface in general, it sort of makes sense that an object like a MER would get wind-cleaned several times over the course of a Martian year.

If there was nothing happening on this surface except steady dust accumulation, the local surface would be buried in millions of years' worth of dustfall. The winds have to be capable of moving the dust along, or else the rocks would have dust caps and be buried in airfall dust. The fact that the rocks are not generally dust-covered (and are in fact aeolian-sculpted) and the soil is not completely covered with airfall dust argues for enough wind to blow the dust off the rocks at a greater rate than the dust falls out of the air.

Of course, no one could have known if the periodicity of deposition/deflation events would be timed well enough to keep a solar powered rover working over a long haul. And extreme dustfall events, like global dust storms, would still probably doom a MER. But, on average, what we observe on the scene suggests an environment where solar panels will be cleaned just slightly more than they will be dirtied.

If you want more proof of this general charateristic of Mars, look at the HiRISE images of the Vikings. They retain some of their blue-white coloration to this day, which means they have been cleaned more than they have been dirtied. It's only a gross confirmation, but it suggests that objects on Mars won't become (or remain) completely dust-covered on the scale of decades to centuries.

-the other Doug