Doug's latest conversation with Jim is now online here:

Rover Audio Updates

Doug says it'll probably be mid-February for the next installment.

There is a lot of interesting info in this one....transcriptions anybody?

--Emily

Here's 6:00 to 11:00

JB: Right. No, that's exactly right. You guys are all… Everybody is seeing the images on the web almost the same time we are so you're coming to the right conclusion.

Its been, it's actually been a very interesting mix these last few weeks of driving across what may be lava flows, ancient lava flows what geologists would call vesicular rocks -- full of holes and vesicles from, you know, ancient gas bubbles in lava flows. The vulcanologists on the team have just been giddy looking at these things. Just the other day with the microscope Ken Herkenhoff and his team took a spectacular mosaic of this, this little, little rock called, I think it was Gong…

DE: Gong Gong -- Gong Gong

JB: Yes, Right. Right Following the Chinese New Year theme, but they are some of the most spectacular microscopic images of texture and detail this heavily eroded vesicular rock surface. And then you know, a day later we're driving across sandy, sparsely, rocky terrain and then another day later we're starting to head up towards a ridge which is rocky again. So we're seeing a real diversity of terrain that's in some ways reminiscent of what we saw on parts of the plains of Gusev before getting to Columbia Hills.

DE : Switching back to yestersol, I've trolled my way through the pancam tracking site and I've kind of totaled up all the imaging taken on sol 738 an I thought we could kind of briefly trot through it to identify kind of what each sequence is about, which order they tend to come and so forth.

JB: Right

DE: Now if you've got that list in front of you

JB: I do

DOUG: Is there any of that imaging that happens before driving on an average drive sol?

JB: Yes and no. The first thing to point out is that this list which comes from the pancam data tracking site which everyone can get to, is not in time-order. There are separate ways to make time-ordered lists but this is just sort of an alphabetized, numerically alphabetized list of the sequences so we'll have to pick our way through it a little bit in time order.

DE: yeah

JB: The first thing we do once we've done a drive is take post-drive imaging. And that will always involve a navcam image, usually at least trying to get the sort of hemisphere look in front of us, and that usually takes about five images so you'll see these listed as five-by-ones. And if we can, if we can afford the critical bits that we can get down in the next downlink we'll augment that with pancams as well. That's also an important thing to do in cases like now where the resolution of the pancam would matter -- where it will help the rover drivers to "pick their way" like you said, between rocks or around certain dunes, things like that.

So we will typically do, we will always do a navcam post-drive and you see that show up on your list as navcam five-by-one az. two-sixteen three B-P-P. Then we'll also usually do some kind of a pancam and I do see one in… farther down called pancam drive directions six-by-one L seven R one. Do you want me to decode a little bit of this? Demystify this a little bit more?

DE: Go for it. Yeah.

JB: OK. B-P-P, three B-P-P that means three bits per pixel. That's a way to quantify the compression -- how compressed are the images.

We start all the cameras on the rovers are twelve bit per pixel. They can go from zero to forty-ninety-five data numbers. With some of them we compress them on board from twelve down to eight bits so that we're not transmitting just noise back and so each original pixel we'll be either eight or twelve bits and then we can compress that down to some other smaller number of bits. So we express that compression in this B-P-P parameter.

So for example if we had a twelve bit image and we are compressing by about a factor of ten, or a factor of twelve, we'd end up with one bit per pixel in the end and that's just an average representation of how many bits worth of information each pixel will end up with. It doesn't work out that every pixel gets exactly compressed the same way. Our compressor is very smart it uses wavelets and actually analyzes the image and finds the places that are more bland and compresses them more heavily, like the sky, or a big flat dune, and preserves the detail in places that are sort of intrinsic and more rich in resolution. So that's what that B-P-P means. .......

redundant

Just as a heads up - I think some people might have got confused between the two different updates

It's a whole lot of Q'n'A in not a lot of time ( cumulatively, almost as much as the Steve one from last year )

We'll have one thread for each new Q'n'A for people transcribing and discussing what was said IN the Q'n'A - and then we'll keep that one other thread for new questions from people here, as well as Q's submitted via TPS.

Got it

Good.

Doug

You know Doug, that "Gong-Gong" audio clip of yours is just too good to go to waste. I'm going to separate it as a small wav which I can post whenever you give someone a warning. Then we can all click on the audio of you saying "Gong-Gong!"

GONG GONG GONG GONG

You want to hear how I pronounced Karatepe before I heard Steve say it

Doug

You can say that again! (ducks)

Um - so which thread is which? Am I in the Transcription or the Question Queue right now? Or do you mean you want ALL FUTURE question suggestions posted back in the original thread?

We're supposed to get 5-8" of snow tonight, so I think I may have some time on my hands tomorrow.

I'll take 0:00 to 6:00 between shoveling sessions...

Pancam update 31-Jan-06
00:00 - 6:00

DE: This is Doug Ellison from UnmannedSpaceflight.com with a new Pancam update for January the 31st, 2006. It is Sol 719 for Opportunity and it's just turned to Sol 740 for Spirit. Opportunity's only done a very short drive since the IDD shoulder problem, and it looks - in this parking mode of slapping its hand on top of its head - as if the RAT contact sensor's very close to some of the solar cells on that front-left array. How close is that, and how many more images are you having to take to check that the arm's in the right place before you can do any driving?

JB: Right. It is quite close, and I don't know the exact numbers, I don't want to quote an exact number, but it's on the order of a few, on the order of five centimeters, something like that. So it is relatively close. And that mode, that "elbow-first" mode was designed after a lot of careful analysis and testing by the rover team at JPL to be what they thought would be the best way to do these small bumps. And a bump is just rover lingo for a small forward or backward motion to try to get a specific target into what's called the work volume. That is the volume of space in front of the rover that the arm can put its different instruments down into. So typically we'll do an approach up to some target, get relatively close, sometimes get the target right in the work volume, but more often than not have to do a bump the following sol to get a juicy target of interest into where we want. And so their analysis with the test rover at JPL with the rover software showed that stowing the arm in this way would provide what they believe to be a safe environment for driving small distances. So that said, it's not at all clear, and it's the subject of a lot of current analysis that we'll be driving long distances that way, we don't know. That's something that the rover drivers and the mobility team and engineers are working very hard to try to figure out. What's the best way to do long drives in this new mission operation scenario.

DE: Potential for having a mode for when looking around a few local targets, and then another way of parking it for longer transits.

JB: I think that's, something like that, maybe a hybrid way to drive. I think that might be likely. But I still, I think it's premature and it's going to require some more time for them to complete their analysis.

DE: Recently through the Exploratorium, and I'm not sure if this is an Exploratorium and JPL raw sites issue or a real rover issue, an awful lot of pretty old Opportunity images coming down, a lot of autonav images, and some more of them from 50+ sols ago. Is that clearing the Flash out for some conscious reason, or is it just the priorities come down to that level?

JB: Yeah, exactly, it’s the latter. You know we have, basically each rover has a hard disk, essentially, of Flash memory onboard, and every product, every picture that we take, every spectrum that we take gets assigned a priority, and we literally downlink in that queue according to priority. So the high priority stuff that we need for driving tomorrow will come down first. And every day we try to make sure we’re acquiring roughly what we can downlink, sort of “live within our means” if you will. Some days we will eat more than we can downlink, if you will, and that causes the Flash to fill up and we’ll put products that aren’t tactically necessary for tomorrow’s decisions in lower priorities. So what you’re seeing is a manifestation, I think, of two things: one, that we’ve had some very good downlinks over the last week or so, so we’re able to dig deeply into the lower priority Flash bins, and the second thing is, and, you know, frankly, we’re sort of running out of things to do…

DE: [laughs] I was going to suggest that…

JB: …in our current location. We’ve taken this spectacular 13 filter panorama, 360 degrees, we’ve done all kinds of various monitoring, atmospheric monitoring, deck dust monitoring. We’ve taken a huge number of these super res - super resolution – targets of these fascinating features all around us, but we’re even starting to run out of those to look at in great detail. And so you’re seeing a net pulling of information out of the rover relative to putting new information in. So it’s not a bad thing to finally get those products down, of course we would never have taken them if we didn’t hope to get them down eventually, but we’re just now starting to get down in those deeper levels of the Flash memory.

DE: In hanging around so long at that region, Opportunity’s finally done something that Pathfinder did, just take its panorama with every filter.

JB: [laughs] exactly, exactly.

DE: Switching to the other side of the planet, Spirit seems to be doing some fairly good driving recently, 739 imagery, some of it has just popped down, and the driving terrain seems to be a bit mixed. There seems to some fairly dusty and fairly large rocky terrain, but also some fairly easy driving if you can pick your way through it. How is it from the inside?

I'll take another 5 minute chunk, 11:00-16:00...

I went over my 5 minutes to get the Tau discussion in. Seeing how far it is now, I'll try to get the remaining 6:30 transcribed over the weekend.

Great nuts-and-bolts discussion here - thanks for doing this, Doug!

===========================================

11:00 – 18:50

JB: ...so that's what that BPP means and when you see a higher number, 3 bits per pixel, 4 bits per pixel, that's a much higher quality, less compressed image than a 1 BPP or a 0.5 BPP. Sort of the ultimate pinnacle of compression is, if you ever see something called "LOCO", it doesn't mean that the image is a little bit crazy...

DE: [laughs]

JB: ...in a Mexican kind of way, it means that the image is LOsslessly COmpressed. L-O-C-O. It's our lossless compressor, there has been no compression of the images, so there shouldn't be artifacts, there shouldn't be loss of information.

DE: LOCO tends to be used, it would appear, a great deal with the Microscopic Imager more than anything else.

JB: We use it, certainly with the MI, that's right, and also we use it quite a bit with the Pancam. You see it a lot on Opportunity lately for cases where we're very interested in the very fine scale morphology, that lamination, those festoons, those very small scale features, you'll see LOCO used because we don't want to see compression artifacts. We'll also use it like we did recently with Opportunity, when we're looking at the sky with stars or - we took some beautiful images the other day of the Earth and Jupiter and Venus rising. We're going to be sending around an image, hopefully shortly, this week sometime, which might set some kind of Martian planetary observation record, because we've got Mars, of course, in the frame and also Venus, Jupiter, and the Earth all in the same set of images. So in those kinds of cases we really need lossless, otherwise these very faint, little stars and planets would disappear in the compression artifacts.

DE: You also get "ultimates" and "penultimates", front and rear hazcam, how do they tie in with the end of the day's driving?

JB: Right. Those are the second-to-last and the last images taken by the hazcams during the drive. We used to actually take one more set, the next-to-second-to-last, which is, actually we learned that the word for that is the "antepenultimate". So we'd take antepenultimate, penultimate, and then ultimate. And what those would do is give us our last look before we drive into the work volume, of what is there. And the ultimate is often used for choosing targets, and the stereo pair from the ultimate hazcams is used to build that map of what we can reach with the arm in the work volume. And the wonderful tools put together by the JPL folks allow us to see in visual form - we can put the MI down on this rock, that patch of soil, we can put the APXS down on that rock, etc, etc, from the maps that are built up from these ultimate hazcam images.

DE: Fairly regularly, you see “pancam clast survey”, or sometimes it will have a target name. Is “clast survey” for a full filter imaging sequence or something you don’t have a name for yet?

JB: No, it’s representative of a just a systematic set of observations that we’ve been doing all the way back to the beginning. Just sort of randomly sampling whatever happens to be in front of us, right in front of the rover, where the pancam resolution, of course, is the best. Just randomly sampling whatever little rocks, soil patches, etc. happen to be there for us to view. And the idea is that by just randomly sampling over time, and I think we’ve done this, we’ve built up this statistically representative dataset of what the fine scale structure of the surface looks like. When we can afford to do so, when we can afford to spend the bits to do that in color, we’ll spend the bits to do that in color. So sometimes you’ll see it be all colors, sometimes you’ll see it just be a subset of colors. And when we can’t afford the bits in downlink or the bits in flash or the time to take the colors, we’ll just do it using the blue stereo filters, because the blue stereo filters give us our best resolution, our highest fidelity detail on the surface.

DE: Would that tie in with the pancam nearfield starboard observation on 738?

JB: Yeah. Nearfield starboard is related, we have port and starboard, just sort of whatever happens to be over our left wing, whatever happens to be over our right wing as part of these surveys as well. Those we used extensively during the traverse to the Columbia Hills, because those regions are also places where the MiniTES can see very well. It’s difficult for the MiniTES, impossible, actually, for the MiniTES to see right in front of the rover where we do the clast surveys. So these nearfield ones are a little bit farther out at regions where we can get the infrared properties, and, of course, the beautiful pancam pictures.

DE: There’s also some, I assume, atmospheric observations, you’ve got pancam tau and pancam sky spot.

JB: Right, right. And we try to do these every day where possible. I think we’ve done the taus every day. Tau is another one of these inside terms. If you’ll indulge me to get a little bit mathematical…

DE: [laughs] please do!

JB: OK. You’ve got sunlight coming through the atmosphere, and the sunlight is attenuated by dust in the atmosphere. So the sun is, of course, dimmer than it would normally be if there was no atmosphere. The attenuation goes as “e to the minus tau”. Tau is a little term in the exponent, so it’s an exponential attenuation and that’s what tau means. So when we measure tau we’re measuring that term on the exponent, “e to the minus whatever” that is attenuating the sun. And on a dusty day that tau can be 1 or 2, on a clear day it can be less than .5, .4, the lowest we’ve ever seen, which I think comes from Spirit, is about .2, and that’s in fact the lowest tau or opacity that’s ever been measured from the surface. Lower than anything that Viking or Pathfinder saw. So we just look at the sun with our pancam solar filters, we know how bright the sun is from measurements made from space, from the Earth, and from other spacecraft. And so we then see what we measure on the surface, compare the two, and the difference is that tau factor, that exponential factor, and that’s how we monitor how much dust is in the atmosphere. And then other things like “sky spot”, or you might see “radiance thumbs”, or “sky survey” – these are systematic atmospheric measurements that are designed to measure how the dust is distributed in the atmosphere, how it changes from day-to-day, not just where we happen to be looking at the sun, but other parts of the sky, and also with time. There’s a big change in dust every day, form day to day, there’s big changes from season to season, and it turns out there’s changes from hour to hour as well. And that affects the sky color, that affects how much power we get at the rovers, that affects just the general nature of how the Martian atmosphere scatters light. I think it’s going to be an incredible thing, Doug, when people go there someday, just to experience how much the brightness and color change with time. People like us who live in cloudy climates…

DE: [laughs]

JB: …are used to thinking about “well, it’s a bright day – it’s a dark day”, and I think the Martians, when they eventually live there, will be thinking about those kind things too.

OK - here's the last of the 1/31 Pancam update transcription. This update should be ready for "stitching"

===========================

18:50-25:14

DE: Also, one feature that gets scattered through these lists quite a lot is "F0006FS Commanded". I'm assuming, or guessing, that that's flight software commanded, and it's where the software - it's not a specific command it's taking of an image, but the flight software saying "all right, I've got to find the sun, so I've got to take some pictures", or "I'm doing autonav, so I've got to take some pictures".

JB: Precisely. You don't need me at all, you've figured it out.

DE: [laughs]

JB: No, that's absolutely right, and we can't predict ahead of time, for example, how many pictures it will take to find the sun, or how many autonav images the rover will need to drive a certain distance. So we have to budget kind of carefully for those and assume conservative - make conservative assumptions about how much data volume each of these automatic activities will take. And so this activity, it's called "flash management", and we actually have to be really careful about that, because the system is designed so that if we fill up the flash memory - what it does is it just automatically pushes out the lower priority stuff and puts your new stuff in. So we may have low priority observations that were taken many sols ago, like the stuff you're seeing come down now, that we do want to get down and we don't want to lose, because we spent the time and power way back when taking the data, we just don't have high priority. But we don't want them to be shoved off the end and thrown out into the aether and never to appear. So we always have to be careful to watch our intake versus output.

DE: I've done the maths, got a calculator out, added up all of the megabits for sol 738, and all the duration for 738, and I've come to a value of about 120 megabits for the sol, and about 69 minutes of imaging. Now if you get creative with Google, you can actually find a listing of every UHF pass, and I've found that yesterday afternoon there was 118 megabits, estimated, for a UHF pass, and then, what would have been, I assume, very early on sol 739, another 160 megabits. Roughly how much of the imagery, I mean you've touched on this with the priority idea, roughly how much of it do you get down, or how much do you need to get down to successfully be able to plan for the following sol?

JB: Yeah, you've hit on exactly on the kinds of discussions and calculations that we have to do every day. We try very hard to make sure that whatever we need for the decision to drive tomorrow comes down in what is typically that 100 megabits. That number varies between 60 and 150 depending on the details of the Odyssey pass. But we try to make sure that within that roughly 100 megabits at the end of every sol we can get down, sent to us, all the information we need to make tomorrow's drive decision. Because waiting for the morning Odyssey pass is too late. We have to have all the commands built, and that's a process that happens while the rovers sleep at night, and that takes many hours. There's people time, and actually writing the sequences, there has to be validation and checking to make sure we're not gonna send up some command that's going to do something bad. So all of that takes time, and if we waited until the morning Odyssey pass, that's too late. So we have to get all the critical drive stuff like that Navcam data, like the Pancam data, like the Hazcam images that are post-drive that will allow us to look at the work volume. Microscope images that will tell us that we got these beautiful pictures, that there weren't any problems and it wasn't out of focus. Anything that's critical has to come down in that pass. There's one cool trick that we developed a long time ago, and that's these things called thumbnails - I don't know if you know about thumbnails...

DE: The very first Pancam images we ever saw...

JB: Yes, yes,

DE: Was the tiny, tiny,

JB: Yup, yup

DE: 64 x 64 thumbnail color image.

JB: Yup, yup. And those were developed so that we would have a clue that the lower priority stuff that isn't sent down in that critical pass was taken and is OK. So we take these beautiful pancam images, 1024 x 1024, 1/3 of a milliradian per pixel and we compress them down into these unbelievable 64 x 64 ugly products. But at least they tell us "Yes, we took it, we targetted it correctly, the rock is in the center of the frame, we got it at the time of day we wanted, the sequence executed successfully". And we can send that tiny number of kilobits down in the critical pass. So I had this nightmare scenario that I went back and forth with Steve Squyres about before we landed saying "we're sending these beautiful cameras and what happens if we just get the thumbnail down and we don't survive the night, or we don't get that second orbiter pass, all we'll have to show for this spectactular resolution is a 64 x 64 image! Aaaah!"

DE: [laughs]

JB: But luckily everything worked out just fine. But having those thumbnails is a wonderful little insurance policy that you know that what you wanted is in there, it's safe, it's sitting at a lower priority and eventually it'll come down.

DE: And they are, data volume wise, they're absolutely tiny, just a fraction of a full frame.

JB: Yeah, they're 5-10 kilobits, around that size. Just tiny.

DE: Jim, we'll leave it there, I'm sure we'll speak again soon, and thank you very much for answering these questions.

JB: You're very welcome, it's great talking to you.

DE: So that's it for this Pancam update. I'd like to thank Jim for taking the time to answer our questions, I'd like to thank The Planetary Society for hosting this file, and Emily Lakdawalla for managing the questions for me. If you have a question you'd like asked in the next Pancam update, then please e-mail it to Emily at blog@planetary.org, and I'll speak to you again soon.