OK - here's the last of the 1/31 Pancam update transcription. This update should be ready for "stitching"
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.
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!"
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 firstname.lastname@example.org, and I'll speak to you again soon.