Question -- is there anything about the composition of the ablative on this heat shield, which does differ from previous Mars lander heat shields, that would make the possibility of contamination to the rover greater than that for, say, Oppy visiting her heat shield? Or lesser?

-the other Doug

Yeah -- for example, the approach shots had the sun on completely the wrong side of Mars. But you're absolutely right, the animations felt extraordinary accurate overall. I was highly impressed.

-the other Doug

Yes, very definitely interested.



-the other Doug

Well... Malin and Edgett proposed the burial scenario in 2000. Several others have tried to knock down that theory by saying it requires greater erosional rates than they can postulate for the deflation, but the alternate hypotheses (like preferential aeolian deposition on the central mound or spring-fed mound building) seem to also have problems based on observations of the apparent layering in the upper unit of Mt. Sharp, the lack of breaching of the northern wall that would have occurred if a Great Northern Sea had flooded the crater, etc.. So, the burial model is still considered viable, I think, based on what I've read (including the Wray review you posted here).

I'm certainly hopeful that the ground truth we get from in situ analysis of the rocks of the lower mound (and hopefully of the upper unit) will shed more light on the question.

-the other Doug

My only concern with geology (areography?) out on the crater floor is that Gale seems to have been completely buried at some point and everything except Mt. Sharp has been slowly eroded back down to where the crater rim is significantly higher than the floor. In the absence of tectonic forces to push up a mountain, I can't come up with a good way for the central peak of a crater to be 5 kilometers tall when the crater walls are only 2 km tall unless the whole landscape was built up to the top level of the mountain and then deflated over billions of years.

We will see depositional stratigraphy in the walls of Mt. Sharp. But what lies on the crater floor is likely to be a mish-mash of rocks and fines that have been transported or left as lag deposits by the same processes that deflated the original landscape. Add likely water flow into the crater from both the crater walls and from Mt. Sharp, and you get layers of material transported from elsewhere, with large admixtures of ejecta, impact melt, brecciated rock both formed in place at Gale and washed down from the rim into the crater, brecciated material transported by impacts from elsewhere, and windblown sediments that have been deposited and deflated in cycles over the years.

In other words, rather like the Viking 1 and Pathfinder sites, almost everything we see on the floor of the crater was likely not formed in place but has been transported from unspecified points elsewhere. That makes it darned near impossible to establish relationships based on stratigraphy.

-the other Doug

Ah, the voice of someone who actually knows the man. I'll never argue with superior information to my own.

Thinking about it, my own reactions to Mr. Lee probably come from him having the arrogance to think he could write sequels to A.C. Clarke's "Rendezvous with Rama" and putting out what struck me as not excellent sf in the Clarke style but inferior pot-boilers reminiscent of Jacqueline Susanne's work, just not as well written. As an old Clarke fan, I suppose I would regard with mistrust anyone who would try and take up Sir Arthur's mantle, and the attempts I have made to read Mr. Lee's works have always bogged down in disgust. (Again, while I've done film criticism professionally, I'm not a literary critic, so I'll say once more that YMMV. There's no accounting for some peoples' tastes -- including my own.)

I did find one short sequence in "Mega Mars Rover" involving Mr. Lee quite interesting. It was what looked like a design review meeting of some stripe, with John Grotzinger chairing the meeting and Gentry Lee pushing hard on some point or another (the only part of the discussion shown was Lee insisting that the design specs are one thing but what they're discussing now is something else again), and Grotzinger saying he's extremely unhappy and pointing at Lee as he said it. The editing of the discussion made it impossible to tell whether Grotzinger was upset at Lee for pursuing with great energy something that Grotzinger didn't want to pursue, or if Lee was pointing out some problem in planning that no one else had perceived up to this point.

-the other Doug

I love the concept of TiME, but I have to say that I have been wanting to see some heat flow information from Mars for quite some time. The seismic data will be very useful, but again, heat flow data will tell us a lot about the rate at which Mars' core cooled, thus letting us understand better the process of creating global magnetic fields in rocky planets. That's of great interest to me.

-the other Doug

I just caught a special entitled "Mega Mars Rover" on the National Geographic channel. It was a workmanlike piece in terms of the documentary style, focusing on the design and fabrication stages of the MSL project, following through launch and with coverage of the actual landing prepared at the very last minute and slotted in to its assigned places in the script.

It featured some very good interviews with people like Adam Steltzner and Rob Manning, following issues like the main parachute testing crises and the failure of the dry-lube concept. It was also well-crafted for such a documentary, beginning with scenes from the actual landing (controllers reporting key EDL milestones, celebrating after landing is confirmed, etc.) and then going back to the beginning of the project to illustrate how all those people jumping up and down and hugging in the control room got to that special moment in their lives, and the epic struggles they all went through in the process.

The only thing I didn't so much care for was what seemd to be a lot of screen and voiceover time from Gentry Lee. I understand the guy was involved in the MSL program during its design phase, and I do respect him as an engineer. There is just something about the guy that makes me uncomfortable -- sort of like I would never want to have a casual conversation with him, 'cause I'd be afraid that any intelligent observations I might make would end up in his next conversation with someone else, rebranded as his own ideas. That could just be my own take, though, YMMV. It's not like I've ever actually met the man.

The high point of the piece, for me, was a series of incredibly high-quality CGI graphics of EDL which landed Curiosity inside a very good simulation of Gale Crater, though along the rim of the Victoria-sized crater in the eastern side of the landing ellipse. This was a higher quality CGI graphics version of MSL's EDL than I have ever seen before; they obviously spent a lot of time and money on getting the details correct.

In addition to the standard EDL and skycrane images, they prepared these same high-quality animations of various alternate scenarios of the landing sequence, using different landing techniques or illustrating perils of the skycrane technique, including:

- dropping MSL in airbags and watching it splatter into thousands of pieces upon impact;

- landing MSL on a legged landing stage onto a moderate slope, such that the top-heavy lander configuration flipped over a few times;

- landing MSL on the skycrane, having the bridle cut fail, and as the descent stage flies away little Curiosity gets dragged along with it, pieces breaking off as it slips over the rim of a crater and out of sight, except for bits and pieces flying up and then the big puff of cloud as the descent stage augurs in, apparently right on top of the rover.

Of course, they also had multi-angle views of a nominal EDL and skycrane maneuver, including an animation of heat shield separation above Gale that was scarily near-identical to the MARDI view. The only thing that wasn't realistic about the animation of the landing itself (besides being a good deal east of the actual landing point) was the lack of much dust being kicked up by the descent stage motors. Then again, no one was expecting the kind of surface disturbance we actually did see.

On the whole, a very well done piece for an "instant documentary" on a breaking news event.

-the other Doug

Good thing my floor needed a good sweeping, 'cause I can't get my bearded jaw off the floor right now.

What. Amazing. Pictures.

Yeah... where did that swear jar go? I got enough amazed interjections on the tip of my tongue, here, to start a fund to build and fly another MSL.



-the other Doug

I don't believe the 7-millibar atmospheric pressure is enough to move that chute once it's laid out on the ground. The chutes from the MER rovers were observed off and on from when they first draped themselves over the ground, and neither did more than ripple slightly, if that.

Now, they won't drive Curiosity anywhere near the 'chute, but not because they're afraid the chute will blow on top of her. Rather, it's for the same reason they wouldn't drive Spirit or Oppy to their 'chutes -- if you drive just a little too far in the wrong direction, you could get your wheels tangled in the riser cords, and not even a nuclear-powered rover has wheel motors strong enough to drive itself and also drag a parachute and backshell along after it...

-the other Doug

EDIT -- Emily beat me to it. Sorry to be repetitive, there. dvd

Bjorn's excellent colorization of the navcam pan highlights a very valuable aspect of the color imagery.

The descent plume pits show a distinctly gray layer of material that has been excavated and overlies the otherwise reddish fines. The material seems to have been excavated from very near the bottoms of the pits, as it begins to appear on the pit wall very nearly from the bottom, and it barely clears the outside wall of the mound. The gray ejecta only appears on the "outboard" sides of the pits, those facing away from the rover and in the direction of the angled engine plumes.

And in all but one of the pits the material at the bottom looks reddish, not gray. I thought that was very noticeable even in the thumbnail pan, and it looks even more obvious in this great colorization.

I'm certainly open to the concept that the gray fines were originally reddish and have been turned gray by some interaction with the rocket exhaust, but this looks for all the world like there is a discrete gray layer in this regolith that is sandwiched between layers of reddish fines.

Interesting.

Of course, the full-resolution images of the pits will be more instructional, I'm sure. But even at this point, with a combination of color data and high-resolution B&W images and not even waiting for the full res mastcams, we're seeing some really interesting things, here.

-the other Doug

That's exactly what the MSL science operations group will, I am sure, be deciding over the next days and weeks. I imagine they will first start making decisions about where in the near area they will drive (if anywhere) to check out the rest of the systems, sensors and probes, and then they will unveil a plan for the next few months. I'd guess they'll lay out a traverse plan that will get them to the flanks of Mt. Sharp and do a lot of drive-by science on the way.

But while we can speculate and guess what they'll come up with, we won't know anything, I'm sure, until they do their studies of the area and decide on next steps.

-the other Doug

I'm real pleased at how much subtle color differentiation is visible in the Mastcam pan, even at thumbnail resolution. I did notice that Mike Malin said they had to brighten up the thumbnails as they originally came in rather dark...

-the other Doug

Really great pan, Ant! I'm really going to enjoy the vistas from this place, I think.

-the other Doug

I think we disagree a bit on the presentation of the raws, ugordan. For those who pipe the latest images directly into their photoshop setups, and applying a contrast and brightness enhancement is an automated part of the process, the raws are great. For the average Joes out there with a moderate interest in the program, I'm thinking that they're all a bit bemused and wondering why we landed at such a dark, murky spot on Mars.

Y'know, just sayin'...

-the other Doug

You know, I was expecting to be able to see a little height on the dunes in the dark-sand dune field. They cast shadows from the dune peaks in the overhead images, I expected to see a slightly choppy-looking top to them. In these surface images thus far, they look like a dark band painted onto the surface with no real height to them at all.

I understand we're probably five km or more from the near edge of the dune field, but still... is this just a function of our distance from them? Or are the dark-sand dunes not as tall as they look from above?

-the other Doug

I remember Bradbury on some of the coverage, but CBS ran four different coverage periods, for the far and near encounters on both Mariners 6 and 7. I won't swear that Bradbury was on the final installment. (I mean, hey, it was 43 years ago, after all...)

-the other Doug

And on an historical note, how many of us who sat around our television sets watching the CBS News live coverage of the close approach of Mariner 7 as it flew by Mars, on August 5, 1969, guessed that 43 years and a day later we'd be watching Curiosity being lowered gently to the ground on a rope?



-the other Doug

The navcam raws seem to have a lot less contrast than what I'm used to seeing from the same types of cameras on the MERs. I'm seeing this not only in the full frames from the panoramic scene but also (as much as can be told from the thumbnails) the deck pan, as well.

Do we have pronouncedly less contrast in the scene itself than we had at either Gusev or Meridiani, or are we looking at some inherent difference in the contrast stretch in the raws as they are processed and sent back? I mean, if the deck pan is that dark gray and it's all due to actual lack of contrast in the scene, I'd be wondering when the severe dust storm settled in over Curiosity... either that, or when did someone sneak into the aeroshell and paint our girl dark gray?

-the other Doug

Well, even if we steer wide and clear of the descent stage crash site, I imagine Curiosity will eventually gain enough altitude along the flank of Mt. Sharp to be able to look back and get a nice view of the crash site. That ought to clear up any mysteries as to what we might be seeing in that first clean hazcam.

So -- someone estimated that the hazcam images were taken 22 seconds after touchdown? I guess that means we couldn't have caught the descent stage in flight, so the RHA must be a post-crash cloud. Although I guess it depends on how long the thing would have stayed up in the air after its translation turn followed by six seconds of thrust.

-the other Doug

Not much from the surface, no. Though here we do have an image taken by Surveyor 1 of its own foot pad, taken at night by Earthlight. It was a 4-minute exposure, IIRC.

-the other Doug

OK, kewl. Those spots just looked really fresh. Sorry I didn't run a comparison with the pre-landing image, there.

Makes you wonder what disturbed that crater, though... again, the disturbances look quite fresh, and the pattern looks quite similar to the one seen in the little crater just downrange of the main descent stage impact, where Occam's Razor would lead you to believe that the disturbances were indeed from the descent stage crash. Maybe a little ejecta from a nearby small impact knocked into the uprange crater sometime in the reasonably recent past?

-the other Doug

I've taken a closer look at the descent stage crash site, and I annotated it a bit to point out a few things I've noticed.

First off, I've drawn red arrows to point out what appear to be secondary impacts, mostly without any streaking of ejecta, just very dark spots where they don't appear to belong. I imagine a few of these are rock shadows, but most of them appear to be freshly disturbed soil. One area I really noticed was a small crater nearly under the stage's flyaway path that has four very dark spots in it. It's about the only sign of disturbance that is uprange of the crash site.

The green arrows point out four distinct plumes that fan out from what appears to be the main impact site. The northenmost of the four plumes are connected, almost just a small side-plume from a main plume. The other two plumes are very distinct and separate from the rest. Looks almost like the descent stage flipped over and hit the ground with the engines firing in the direction of flight, although I certainly don't insist on that interpretation.

Finally, there is this aureole-like feature just uprange of the impact point that I have rather imperfectly tried to outline in yellow. I see a very light disturbance in this area, much less darkened than the ejecta spray downrange of the impact. This uprange feature also appears to show radial spiking around its outside extent.

The combination of the four disturbed points in the crater uprange of the impact point and the plumes fanning forward from the impact point again makes me wonder exactly what happened as the stage came in for its crash-landing. I don't even know if it's possible for the engines to have been firing by the time it impacted; the fans I see may be separate ejecta events from each of the largest pieces of structure that hit at the main impact point. But it does look awfully suggestive.

-the other Doug

Methinks if we ever use a skycrane type of landing again, we're going to have to program a little more smarts into the descent stage and have it either fly farther away or try to kill its velocity before it crashes. I shudder to think of what might have happened had one of those fragments of descent stage come back and whanged the rover real good...

-the other Doug

The image of the descent stage impact site(s) is really, really interesting. First off, while everything sprays down in the direction of travel, there are very specific plumes angling off about 50 to 60 degrees on either side of the main motion vector. Looks a lot like the angle at which the opposite-side engine pods are mounted from one another.

Could the descent stage have hit the ground with engines running and flipped over, spraying a blast of exhaust ahead of it and along the angles consistent with their attachment to the frame of the stage? And then after hitting ground following the first flip, disintegrated and resulted in the long tongue of disturbance from the initial impact point to the final impact point?

Just random thoughts...

-the other Doug