It's the weekend and this is my 10th (I think) press briefing post. It feels like I've got enough notes to put together something of a "week in review" post. Maybe sometime after today's briefing. We'll see.
Press briefing seems to be delayed. It's after 9 am and NASA TV is playing some robot games thing.
Hrm. Maybe it's not delayed and NASA TV just isn't covering it on the weekends. What a disappointment. Anyone know the story or when NASA TV might replay the briefing? The schedule isn't really explicit.
Ahh, a commenter says it's one hour later. Thanks so much for the info. I guess today I'll get to post after I've had some coffee. Nice :-)
Briefing replay happening now.
Saturday morning press briefing notes:
Jennifer Trosper: After 7 months of being folded up, today is the day that it's unfolded completely. About 3 years ago, Chris and his team were given a huge challenge, essentially putting a square peg into a round hole. Today we get to celebrate the success of Chris and his team who fit our rover into this lander.
Chris Voorhees: It's been a very exciting couple of days for the spacecraft team. Spirit has spent most of the last 7 months crunched up inside of a tetrahedron shaped lander. Over the last couple of days spirit has undergone a reverse origami, an unfolding. Started yesterday performing standup part one and standup part two. This is a sequence of images that shows the first parts of standup raising into position and the front rockers have folded themselves out into their deployed position. Part of that process includes a couple of latches on the side of the vehicle that support the vehicle. There was then a re-raise to make sure those latches were locked in. As part of this morning's process we re-did the re-raise procedure to verify again that they were indeed successfully engaged. We got telemetry that says they were engaged so today we move into part three where spirit really gets into her own. Now the rover lift mechanism that lifted Spirit into her standup position has retracted and the rover is supporting herself. Once that was verified on the ground we went into standup part four, the deployment of the rear wheels. Her rear wheels have been nested against the middle wheels and have been dying to get out. We do that with two pyros that release the wheel and the wheel then deploys itself by driving along a cogged surface. This only takes a few seconds and increases Spirits wheelbase so she is more stable on the surface. The last slide shows our verification that process completed successfully. (hascam images of wheel position change). This latch check ensures that the wheels are deployed all the way out. To continue a tradition I'll do "standup by the numbers". There were 12 pyrotechnic devices, 9 motorized mechanisms, 6 structural latches, 2 sets of stereo hazard avoidance cameras, and numerous other and the other sensors reporting back. The other number is the scores of engineers, analysts, technicians, machinists, that allowed Spirit to perform one of the most complex sequences of deployment on a robotic spacecraft ever. Being successful, we've left spirit in a very comfortable position. She's asleep comfortably supported on all 6 wheels.
Jennifer: As if what Chris just described wasn't enough, we've transferred over 200 megabits of science mission (10 times all of what Pathfinder sent). Now that we're fully sit up, we're getting ready to egress (graphic 5, overhead shot). Tomorrow we're going to release the middle wheels. The other thing that we'll do is move the instrument deployment arm from its launch locked position to its stowed position. After we do that we'll fire cable cutter number 3, the final cable holding the rover to the lander. We've been looking at the egress paths and testers doing simulations in the testbed. We discovered that there is a possibility that as the rover drives down the front ramp the back of the right solar panel could brush up against the airbag. We made decision today to egress out the back. What we'll be doing is to turn the rover 120° and drive down the egress aids on the back of the lander. Turn on Monday night and egress on Tuesday - a bit earlier than we thought. The lander is very flat and we had talked about hyper-extending the petals into the ground to make the lander more level. We now don't believe that this will be necessary. Deck height of 40cm is actually egressable. End of the aid is about 15cm from the ground and that's the drop-off as the rover moves onto the ground.
Joy Crisp: Going back to that "six minutes of terror" and understanding the atmospheric conditions is crucial. Before we landed Spirit, we set up predictions. We've been busy checking our prediction against what Spirit saw. Atmospheric reconstructions is now completed. It was done to determine if any adjustments were needed for Opportunity. The accelerometer and gyro readings derived the profile. The yellow line is temperature. Before spirits landing David Kass and Tim Schofield prepared a predicted temperature. It was derived from recent MGS TES data. Models of the Martian atmosphere have a lot of uncertainty. On earth we take thousands of like measurements per day. On Mars, this is only our fourth time to take such measurements. We were thrilled to see those lines (predictions and actual) match so closely. This is just one piece of the whole analysis of EDL. Pete Theisinger reported yesterday that we're not going to be changing the Opportunity entry angle.
Matt Golombek: Selection of these landing sites took place over 3 years. The two most important things in making the selection were, one, safety, safety, safety, and two, you want it to be scientifically interesting. In the evaluation we made use of, for the first time ever, data from two spacecraft in orbit around Mars, MGS and Odyssey, and they collected enormous amounts of data about these sites. They are the best imaged, the best studied sites anywhere on Mars. We looked at 3-meter MOC images, thermal, radar, albedo, etc. And from that data, we made three broad predictions. 1. The site would be safe - and it was. 2. The site would be trafficable and safe for driving rover - we'll find out soon. And 3. We said it would have substantially fewer rocks than the previous 3 landing sites (turned out to be 3% compared to 20% average at the others). What does remote sensing - thermal, inertial, albedo, topography - say about that area. It's smoother and flatter at 1km, 100m and 5m scales than two other sites we've landed at. In the location we came to rest, a low albedo region, we said it would be less dusty than where we've been before and that seems to have been the case. Pancam is healthy. This new image, panorama looking to south west, relatively smooth and flat surface, sparsely rocky, small circular depressions filled in with dust and light sediment, flat horizon, not much in the way of relief. It's the smoothest, flattest place we've landed on Mars with the possible except of Viking 2. Looking to southwest we see that hill in background, it's being used to try to infer where we landed in the ellipse. Pancam is acquiring images for mini-TES as well as the first spectral spot. 93% of mission success panorama has been acquired and we hope to release that pretty darn soon. (Slide tour of other landing sites) Pathfinder site: Substantially rockier plane. Brighter albedo from dust coating. Viking 1 site: Substantial rocks and dust and drift deposits, raises albedo and makes it a brighter looking place. rolling surface. Viking L2 site: Lots of rock, dust, high albedo, about as smooth and flat as spirit site at the 1km scale but Spirit site has fewer rocks. We predicted that Meridiani will look completely different from the 4 other sites, with substantially lower albedo, very little dust, a dark gray rolling plane.
Mark Lemmon: From the very first images we could tell there was a great deal of dust in the sky. Dust can be a nuisance for getting power but also can be studied from a science point of view. We're getting a good handle on the atmospheric data. In this image see the yellowish brown sky. Also notice in this image and in more distance peaks, dust substantially impacts the visibility of the features at the sight. More distant features are more obscured. Dust makes visibility something like a smoggy summer day in a big city but not the worst smog you've ever seen. We're trying to get a good handle on the dust properties. We're putting that atmospheric data together with information from other sources like the photos of the camera calibration target or dust falling on the magnets. We want to better understand how dust impacts exploration on other planets. We started with measurements from orbit using thermal imaging. We take pictures of the sun to see dimming by dust. It's .9 to 1 on the opacity scale which is a bit more than the estimates we're getting based on the thermal infrared instruments. Solar panels are OK. Also doing evaluations of the coloring of the sky. Imaging teams are making adjustments. Looking at the right in that image (calibration target) you can see a very bright shadow. See that the shadow is maybe 50% as bright as non-shadowed area. Much of the time we're imaging Mars, half of the light is coming from the colored sky and not directly from the sun. See also the mirrors showing Martian sky color. Pathfinder observed several dust devils (images). Gusev crater has perhaps 10 times the dust devil activity as the pathfinder site. We will be observing in the early afternoon hours when it is warm out and dust devil activity should be high. Not seeing many yet. We will get measurements of convection and our team will be describing what's happening at the lower levels of the Martian atmosphere.
Q. Drive off questions. Toward the northeast? What time Tuesday evening? Command path?
Jennifer: Northwest. We continue to command through x-band even though we could use UHF if we chose to. Egress command will be sent a little before midnight (late Tuesday evening).
Q. Rolloff questions: Elevation of lander is 40cm? How far is it gonna roll before all 6 wheels on soil and what is the angle of decline?
Jennifer: The height is about 40 cm on average. The highest point on the lander settled recently (the rear petal) from about 56 cm down to 47 cm. The whole lander has settled a bit since we started retracting airbags. Angle is 30-45° and as the rover weights it down it gets steeper. We'll drive till we get all 6 wheels on the ground, probably half a meter.
Q. Am I right that the lander becomes "just so much metal" when you cut the cable, and can you talk more about that Pancam image?
Jennifer: yes, lander becomes space debris.
Matt: we believe that is ridge/trough topography leading up to those far hills about 2.5 km away. It's reminiscent in some ways to what we saw at the Pathfinder site. At pathfinder we believe it was the result of fluvial activity. We're more reserved about making judgement about the Spirit site this soon. Other evidence of fluvial activity, rounding, concentrations of boulders at tops of ridges the so-called "boulder bars", but we wanna wait a bit before making that judgement.
Q. Question about reconstruction of atmospheric data, you tweaked on Spirit's parachute, is that part of the strategy for Opportunity. And can you talk more about dust on solar panels?
Joy: The team is thinking of increasing dynamic pressure of the parachute opening just like we did on Spirit. This would be a minor adjustments. Part of the picture is monitoring the decay of the dust storm.
Mark: What we know about dust falling on the solar panels is still just a model. Over the course of the mission we'll actually measure that with cameras looking at panels and calibration target.
Jennifer: We spend the first week of the mission working on our power model and with a tau of about .9 we get our predicts to match our actuals so there's a little bit less energy but not significant and as the tau clears up we'll get even more. We don't use all our batteries each day anyway so there's margin there.
Q. About that new panorama segment, there seems to be a craterlike depression that looks like it might have exposure on the far rim. Do you see that?
Matt: There is what appears, - there are literally dozens of these and my personal interpretation is that they are secondary craters, add a little bit of windblown dust and that could be what you are seeing - there is one in that scene that appears more rugged with a higher rim. It could be fresher, a more recent crater, or could be a primary crater. I have not noticed any outcrop in that rim. Precious little "outcrop" except for those far hills two and a half kilometers away.
Q. It looked like at the top of one of those hills there's a tilted bedding.
Matt: There's quite a bit of attention being paid to those far hills. A couple of reasons for that. We've narrowed down our location, those hills are the nearest "different" thing from where we are now. Could be older material that's not eroded and that's the closest "etched material" so there's a debate whether or not that's within rover range (optimistic laughter). One, we've got a stereo fix on those hills from previous orbital camera images. We have a wondrous 2-D model and we believe they're 100m above the plane (not the 50m that we previously thought). In terms of a long-range plan, many of us think that might be a good place to get the rover driving.
Q. If I spent 7 months cramped up like that I'd have cricks and creaks. Is that the case for the rover, maybe metal memory, or is it the case that what you have is what you have?
Chris: For the most part, what you have is what you have. The rover has a slight innate sag that you would see under Martian gravity. In some cases the sag was appropriate and useful to have. That sag has probably developed as we deployed the bogey wheels (last night). The only other thing is that all of the deployments went exceedingly well, drew currents that were lower than expected, which bodes well for the general health and hardware. Standup got us from a lander into a rover and it also works well as a healthcheck for the systems that will be getting us around.
Q. You mentioned an estimate of rock area is about 3%. Isn't that less than orbital predictions which pegged it at about 9% and what does that say about Meridiani? What about that white rock, doesn't look like dust but rather the intrinsic coloring of the rock?
Matt: Yeah, Viking data predicted 7% with a margin of error of 5% (ed. not sure if I got that right. Matt talks really fast) We think that there are areas that have a higher rock concentration, some of those "boulder bars", so I'd call that a match. And yeah, the science team is specifically looking at a family of lighter rocks. Some places you see darker material coming out from underneath that, other places you don't see that. Spectral properties are differ from the reddish ground and dark rocks. It could be a real target.
Q. Tuesday night, what day of the sol is that? Is the science data coming back the same day
Jennifer: That's sol 11. When we egress depends a little bit on testing over the next couple of days. We want to confirm we're moving exactly as we want to be. Will likely do more than one move, multiple decision cycles. A decision cycle is the sending of the command and the return of telemetry/imagery confirming the success of the command. We'll have 2, maybe 3 of those. We don't' expect a delay but it's possible.
Q. I'm delighted that you may egress earlier. Why?
Jennifer: We talked about hyperextension of the petal to level the egress path and we now think that's not necessary so that's one day we don't have to spend moving the lander around to adjust its position. We also didn't plan decision cycles around the UHF paths to the orbiting satellites. We planned on 2 decision cycles per day via DTE comm. Right now we're using the afternoon Odyssey pass to enable a 3rd decision cycle. We did that today and got an unbelievable amount of activity.
emcee note: as usual, we will replay all the images after the briefing, and we plan on a morning briefing Sunday at 9am.
Q. How does the weather compare to anything on Earth. When you talk about dusty is it anything like what we would consider dusty here.
Mark: First, "dust devils" is a somewhat misleading term. They're bigger than tornados are on Earth. They tower above our tornados. Some might be 100m across. In terms of the amount of dust in the atmosphere, it would look like a very dusty day here. Not like the middle of a Sahara desert dust storm but definitely dusty.
