MER press briefing, February 4, 2004
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February 4, 2004
The press briefing is about to begin; notes when it's concluded.
Steve Squyres: Good morning. We've got some really nice stuff for you today. We've taken our first good look at soil in our crater, our home here at Meridiani. There's some really interesting things. Features we've never seen before. I said it was like a cool geologic fieldtrip. Welcome to our first stop. Here you see the Navcam image of the soil in front of the rover and we're zooming in to Pancam image. This caught our eye a couple of days ago. We knew, even from the Navcam images, that we're looking at soil with at least 2 components, at least. We saw a bunch offine grained soil with coarser material on top. The coarser material looked like gravel but when we looked closer, they looked darned round. The nice thing about distinctive characteristics is that every characteristic, a shape, a color, a texture, has a story to tell about how it formed. Only so many ways to make something round. Sort of round could be from tumbling. If they're really round, that narrows down the range of possibilities. Blobs of molten lava thrown in the air, an object accretes layers, ways you can do it. We were very interested to see just how round these stones in Pancam image were. So we stuck out our arm and took a look. We have this robotic arm with a number of instruments, one of which is a Microscopic Imager. MI on the end of the arm. See Hazcam images of arm going through motion of taking image of soil.
Ken Herkenhoff: You've seen pictures from all of Spirit's 10 cameras. Opportunity so far, just 9. Here's the 10th, the Microscopic Imager. Designed to emulate a geologist's 10x handlense. This graphic starts with Pancam view. Zooming in to MI frame. Full field of view is about 3cm across, a little more than an inch. Smallest particles we can resolve are about 1/10th mm across. The larger one is about 3 mm across. MI dust cover has an orange tinted window that can give us crude color information. This is an example of a merge of those two color frames. Zooming in on some particles. Sand grains about 1/10th mm. Various shapes and sizes from 1mm up to a few mm across. The entire image is in full shadow so no sunlight. There's a variety of shapes from spherical to angular. Next image will show an enhanced color version that emphasizes variation in color across these grains. Just right of upper center there's a rather red grain . Those are relatively rare here. Most gains are less red. The variety of particles and shapes here indicates a variety of sources. There are some holes probably from gas bubbles either by volcanic or impact processes that Steve mentioned.
Hap McSween: All of these features are interesting but the really intriguing ones are the round ones. There are a number of geologic process that can yield really round objects. First Pancam suggested little balls, little spheres. MI shows very few are actually spherical, many are flatter or broken and could be derived from the round ones. One process we considered is that grains on a seafloor or in moving water roll around and accrete or grow by adding layers of material. These are called oolites. And we got excited about the possibility that we might have found oolites. The problem is that very few of these objects are spherical balls, they have other shapes, and so they're unlikely to be oolites. Also oolites shouldn't have bubbles, holes we see. Other possibilities is that large meteors when they impact the planet melt some of the target materials and this rock is sprayed out as a fine jet of droplets of liquid, and as they fly through the air they make shapes like dumbbells, teardrops, sometimes buttons. I think I've seen all of those shapes looking at these MI images. They cool quickly into a glass but if a target rock had water, that could cause the gas bubble holes that we see. Volcanoes spew out liquid droplets. But more likely, with violent eruptions have ashes that are buoyed by hot gasses and as they are suspended they begin to coagulate together into rounded pellets we call lapilli. I think it's possible that these things may be lapilli. Also intriguing that many of these things may relate to the outcrop. If this is an ashbed we might be able to find some connections between that, maybe it's weathering and shedding the things that Ken has given us.
Steve: we don't quite know what these things are yet but we've made significant progress in narrowing down the possibilities. The good news is that with the plans we have ahead, in the coming sols we think we can unravel these mysteries. I want to step back for a minute and refresh everybody on the big picture. Recall that the thing that brought us here was the hematite, a mineral that is closely associated with liquid water. Recall also that we're trying to do is to read the geologic record, look at all the different terrain types, look at the different materials, and try to put together using all our tools we have at our disposal, a comprehensive picture of what happened here long ago and whether or not water was involved and whether it was a habitable place. Somewhat cliche, but I've likened this process to the parable of the blind man and the elephant. What we've seen is one small part of the story. We've got to fold that in with other patches of soil, the outcrop, what's above the outcrop, all the other pieces. We have gotten another interesting clue. We're getting more information about composition. This is mini-TES data. Very nice instrument that has provided us some great data. This is one of our images overlayed in color with the concentration of hematite. First mineral map from the surface of another planet. The blue stuff is low in hematite. The red is height in hematite. Tremendous variation. Hematite is fairly low in that rock outcrop. Very high in the material above the outcrop and the material below it. As you get closer to where we sit, you see less and less, particularly at our airbag bounce marks. The place that we have taken the soil measurement is not in this image, it's over way to the right side in the very low-hematite stuff. We've looked at this soil with MI, Mossbauer and we're looking right now as we speak with APXS. We know that from this hematite concentration map that we're looking at a place where we don't expect to see much hematite. In order to see the hematite we're gonna have to move. That's next. The next thing we're gonna do with this rover is to start to head to that outcrop. As we work from right to left across the face of that outcrop initially into an area that is relatively hematite poor but as we head across that outcrop, we're going to be moving into materials that are progressively more and more rich in hematite, we're going to be seeing other pieces of this very complicated scientific elephant. Over to Franz Renz who will be presenting the findings of the Mossbauer spectrometer.
Franz Renz: O have good news. We see a magnetic compound but the bad news is that we don't know which one it is. It will take us a few days to see which one it is. Not as easy because concentration is quite low. The image: Here you see Mossbauer spectra. You see the magnetic phase. You see the signal to noise is very low. That's why we can't identify it yet. It will take us a few days. In the middle you see a feature we've actually seen before on the other side of the planet, a basaltic structure with olivine inside. Olivine has some iron which has lost two electrons. If you're not familiar with this, look at a green wine bottle there the iron which has lost two electrons gives it the green color. The Olivine is green as well. If it grows nicely in color you'll actually get a gemstone called peridot which was the favorite gem of Cleopatra the queen of Egypt who was actually of Greek descendence, but that's a different story (laughter). And besides that we have one iron that's lost three electrons. If you look at a beer bottle, the brown color comes from an iron that's lost 3 electrons with silicates around. It's a basaltic structure as we've seen before and we're happy with this.
Mark Adler: Opportunity has had a very, very productive couple of days. On sol 10 mini-TES checked out and is working well and we've taken a quite a few spectra with that as you can see from the wonderful mineral map of the hematite taken at the Opportunity site. The Mossbaur began its 24 hr integration on sol 10 and completed it on sol 11. That data was collected on sol 11. And we put the APXS down for a 14 hour integration overnight and so that's ongoing right now. It's about 8PM at the Opportunity site right now and it's about 8am at the Sprit site. At Spirit, we're engaged right now on the formatting operation. On sol 30 we attempted to do some science operations. We had a day where we were testing format operation in the testbed so we were going to continue our arm operations on Adirondack, take some MI images and a spectra. Unfortunately at the beginning of that day we tried a sunfind. Didn't succeed, wasn't able to complete the sunfind operation and so activities not allowed to continue because vehicle was not certain of its attitude. So we had to recover from that and later in the day we got a sunfind to succeed. Failure related either to activities ongoing at the spacecraft at the time or a file in the flash corrupted. Bolsters our desire to format flash filesystem and get ourselves back into a clean state. On sol 31 we did preparation for the format operation. Go to sleep early, skip overnight comm passes, get the cold as possible with as much power in batteries as possible. Poor rover woken up early at 6am. Rebooted into cripple mode which does not use flash memory. Flash operations underway. A 4 hour process started about 20 minutes ago that will erase all contents of flash and check hardware, check all the chips. We don't think hardware, but being safe so checking it all. Going through all the 224 (?) megabytes of the flash memory system and erasing it over the next couple of hours. Next we'll reboot and reformat the flash file system. After that we should be in normal operation and we will reintroduce Odyssey pass overnight and tomorrow morning we'll go back to science operation.
Q. Segregation of materials in mini-TES suggests that unlike Gusev, there's very little mixing of fine material. What does that tell you about surface.
Steve: We're still looking. Story we're putting together is that we have a number of different components. We've got the big grains. Starting to narrowing it down what those might be. That they're so strikingly spherical points in very specific directions. We have something that's very red and very fine grained exposed in bounce marks and doesn't seem to have much hematite. Then we've got this sand. Based on Mossbauer and mini-TES and MI, that looks like some finely ground up basaltic sand. That's at least 3 different components there and they're mixed in different ratios in different places. Looking for correlations there. No complete story yet. I'm interested in finding a place with as high as possible concentration of little pebbles and slapping the Mossbauer, APXS, and MI down on those. Find out what just those pebbles are made of. That's going to be interesting. And we're going to dig a hole, in the next few sols, drive to a place where there's some of this stuff and dig a hole with the wheels and see what's below the surface. It's going to take us a while to piece this together. The main thing that I'm getting out of this is that there are several components to this soil and they're unevenly distributed around the crater and who knows what's outside of the crater. that could get even more interesting.
Q. Intriguing things is some seemed to be layered, a rich hematite above bedrock, some seems much patchier.
Steve: Fine particles can be blown by the wind. Little round particles can roll. I'm interested in concentration of these little guys as we get closer to the outcrop. Are they coming from the outcrop? Maybe they're weathering and falling out of the outcrop. I don't know but we have the tools to find out. If we work our way through this problem and piece it together clue by clue, we're gonna get it.
Q. How far traverse from current spot then how far will that be from the outcrop.
Steve: I don't have a really good answer because that was being decided in a meeting I wasn't at. I'm actually off duty today. I think... (off-camera: "three meters and three meters".)
Hap: the trench location is three meters from where we are and the outcrop is about another three meters from that. Relatively short distance.
Q. Steve, a day or two ago a colleague was discussing a parallel traverse along the outcrop.
Steve: Yes. We're going to head towards the right hand side of the outcrop stopping part way along to do some soil investigations, and then we're going to go right up to the outcrop and work our way across it from the right to left, shooting down and to the right with Pancam as we go, getting very, very high-res Pancam and Mini-TES. We've been preparing for this. Mark was taking about managing flash. One thing we've been doing for days now is we've been taking fewer pictures than we'd like, taking fewer spectra than we'd like to take, leaving lots and lots of room in flash memory. Because when we get to that outcrop we're going to hammer on this thing with Pancam in a very big way. We're going to take hundreds and hundreds of megabits of data and fill up that flash real quick.
Q. When I do the stuff on my computer that you're doing on Spirit it scares me to death.
Mark: There might be a reason that we spent last 4 days testing that in the testbed. Not an operation we do lightly. We've reconstructed the environment in testbed as accurately as possible and we've verified also that there's not other possible side effects that the operation could have on the vehicle. For example, we store our flight software images in another area of flash that's separate from the flash file system. We've verified in fact that when we erase that there's no way to corrupt the flight software. The sequence we've developed that's running today checks at every step of the way to make sure that doesn't happen. It is an operation you don't do willy nilly and you've got to make sure that it's done right.
Q. Steve, this is first mineral map done on another planet? What about Spirit's map? What's the outlook for water having existed here?
Steve: Sprit mini-TES produced maps of temperature. These are actual maps of mineral composition. That's a first for this mission. Extrapolating from a few grains of sand to water on Mars, a little hard to do at this point. Stuff we're looking with instruments on the arm at this particular point doesn't really tell us much from a mineralogical standpoint, from a chemical standpoint doesn't tell us much about water. Not until we get to the hematite. There's hardly any hematite in Franz' spectrum. We need to use our mobility to get to where there's more hematite. We're going to have to piece this together bit by bit. Still very early in the mission to do that.
Q. Explain what you hope to tease out of data over the next couple of days. How does hematite vanish in bounce marks?
Hap: We're looking for hematite. It has magnetic fingerprint. That's why we're looking in the region. We don't know yet. We have to carefully evaluate the spectra. Hopefully in a couple of days we can give you an answer.
Steve: We haven't looked at a bounce mark up close yet. One hypothesis, an idea is that the hematite is carried in some of the coarser grains, maybe the really round guys, and there's fines beneath it that doesn't have much hematite in it and bouncing pushes the coarse stuff underneath the fines and Phil's instrument can't see them any more. The MI picture is a 3cm/3cm square. Only a fraction of that surface area is covered by bigger grains. Most of it is that basalt sand. Mossbauer doesn't see that whole 3cm square are. It sees a smaller 1.5cm circular region, probably near the center. It's seeing whatever happens to be in its field of view. We're interested to find out where that was. When you push it down, it may leave an actual imprint. We'll take another MI after moving APXS away to see if we can see a Mossbauer nose-print. Possible that it didn't even hit one of those pebbles. We need to piece this together bit by bit.
Q. Adirondack and arm operations status?
Mark: operations did not complete, the RAT checkout and arm move. Position of arm and Mossbauer exactly where it was before the anomaly started. We'll start again after the format.
Q. When you turn a rock over it's sometimes even more interesting sometimes. Any plans for that? Wouldn't that be interesting?
Mark: We are going to do a trenching with Opportunity.
Steve: Best way is by moving wheels. Trenching operations should push small pebbles. We don't have an arm that can pick up a rock and look underneath. If we find a compelling reason to do so, we might find some clever ways to look at it in ways that the hardware was not necessarily designed for and I'm sure that if I was to propose something like that, I'd have to go to my mission manager and have a long heart to heart talk ;-) Oh man, but there are so many things that are interesting here. I could think of a thousand things that are but there are only so many sols in the mission. But I can assure you that if we find a compelling reason to turn a rock over, Mark and I will have that conversation.
Q. Seems to be some uncertainty of shape of these round rocks, spherical or flattened. Could you nudge them with the arm and see the shape?
Steve: We will see these things move as we contact them with instruments. Mossbauer has a plate that goes to contact with the soil. The thing that will help the most is taking pictures of lots and lots of these things. Unlike the APXS and Mossbauer, MI can do quick photos, about 5 minutes. We can do "touch and go" every day, a quick look at the soil and then go about our business. We should be able to take dozens of MI pictures of the soil over the course of this mission so we could get a statistical characterization. In the MI picture we showed you, there's a grand total of only 2 of those spherical rocks. There might be a range, some broken ones. What do you see if you find a broken one. You can have things that freeze in air or that grow up layer by layer. If we find concentric structure in a broken one, than we're headed down that path. We need to sol by sol take lots and lots and lots of pictures and build up a library.
Ken: We can also do stereo with MI. We can use the arm to place the MI in a couple of different places and where they overlap.... (lost connection). Steve: ....some of the are really, really round.
Q. Mossbauer has narrower field of view. Can you get Mossbauer of specific objects?
Steve: APXS even bigger, 38mm diameter, almost an entire MI field of view. You could try to get really cute, really fancy with positioning. That's hard, man. This is a 5° of freedom robotic manipulator on the surface of another planet that's sort of flexible and has got wheels that can slip in the soil. Right way to do it is to just find a place where there are a whole lot of these things. There are places where there are a bunch of them, much better chance of hitting one.
Q. Trenching 101. Tomorrow, which wheel, how deep, how long?
Steve: Tomorrow is drive, not trench. Mark: Usually front right or front left turns while the other wheels are positioned to prevent rover from moving. Usually direction that pushes dirt in front of the rover. Then we carefully back the rover out of the hole so as not to disturb it and then we're in a position to get the instruments over the hole as well as being able to look at it with Pancam and Mini-TES. It doesn't take very long, typically rotate wheels a couple of dozen times. We take an image after each rotation. Could take an hour or two.
Steve: Worth pointing out too that there's a dual purpose. One purpose is to expose sub-surface material for science value. Also has engineering value. We're in a whole in the ground, a crater. We've got to climb out. Mobility people want to know more about the soil properties. They will get a lot of data to help plan drives. Serves both purposes.
Q. One of the most striking features are impact craters. Heat shields have impacted. Nay plans to visit these two impact craters?
Mark: we have an idea where heat shield impacted crater at Spirit site. We're headed to south side. Impact is north side. That's not our target. Might have done some digging but not the kind that these folks are looking for.
Q. Schedule over the next few days? When will we see Spirit brushing and RATting. When trenching for Opportunity.
Mark: It's sol 32 on Spirit now. Tomorrow we plan to do arm operations, brush operation and MI, and one or both spectrometers. On the following sol we'll repeat that sequence with a grind operation, MI and spectrometers. That would be sol 34. On sol 35 we'll start our drive out. We'll probably drive to north side of lander and point ourselves in a straight line to Bonneville crater. On Opportunity we expect trenching on sol 14. Tomorrow go 3 meters of 6 to the outcrop and do our trenching. Then do the move to outcrop.
Steve: We'll do the trench, take a sol or two to investigate the trench then drive to outcrop and drive across the face of outcrop, probably slap the arm down and look for a day. We'll spend a couple or three sols driving along the front edge of the outcrop taking pictures. Then we have to figure out how to attack the outcrop. We've got a lot more than the outcrop to do. How long we study outcrop depends on that initial data.
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