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Mission Update by Steve Squyres

(Return to archived mission updates list)

August 2005
August 31, 2005

Really sorry that I haven't done an update in so long!

As I think is pretty obvious, Spirit is now at the summit of Husband Hill. Tomorrow we're going to do a press briefing at NASA Headquarters to unveil the Pancam panorama taken from the summit. I think it will stand as one of the signature accomplishments of the mission.

As I write this, Spirit is now perched on a steep slope on the south side of the summit, and is starting to take what should be a spectacular Pancam panorama of the inner basin. Once that's done, we're going to do a little shimmy-step to the left and take the same panorama again, to get some "long-baseline stereo" coverage that we'll use to plan upcoming descent into the Inner Basin.

When will we head down the hill? I don't know yet. We've got a list of things we want to get done in the summit region, and it's pretty long! We're prioritizing, and within a week or so we should be able to set a date by which we'll be ready to start downhill. It all looks pretty tempting down there.

And for those of you who are really into the engineering details: On Sol 581 -- more than nineteen months after we landed -- the solar array output for Spirit was 956 watt-hours. Insane. We have to shut her down every afternoon these days so she won't overheat.

At Meridiani, you may have heard that we had a strange glitch with Opportunity the other day... a "reset", which is basically a reboot of the onboard computer. We're still working out why it happened, but all seems to be well now, and we're back in business and eager to get on to Erebus crater. I'll have a bit to say about some interesting recent science findings at Meridiani in tomorrow's press briefing.

August 17, 2005

Just a quick one today. We had a great drive with Spirit on Sol 576, and we're now approaching the summit region of Husband Hill. What we've learned from the latest images is that the thing we've been calling Summit 1 -- which we had thought from orbital images was the lower of the two summits -- is actually the higher one. So we're bound for Summit 1 now, instead of Summit 2. Near as we can tell, we're only about six vertical meters below it, and the path from here to there does not seem to present any impassable barriers.

The view is getting pretty spectacular, too, with the peaks south of Husband Hill now suddenly in sight. It shouldn't be long.

Oh, yeah, and the cobble we looked at with Opportunity isn't a meteorite, it's a martian rock... and one that's very different from anything we've ever seen before. Busy times...

August 14, 2005

After months of being the "other rover" as she struggled across some pretty barren plains of sand and blueberries, Opportunity has again taken center stage. One of the things we've been wondering about for awhile was whether the blueberries are the same everywhere, or whether they change from place to place if you travel far enough. We're now several kilometers south of Eagle and Endurance, and the answer is the the blueberries here are indeed different. Opportunity did our first RAT hole in quite a few months this week, and the MI images of it are different from anything we've seen before. The berries are more numerous here, and some seem to be smaller than any we've ever seen. And interestingly, some don't appear to be round. We're still debating what this means, but clearly the hematite is distributed a bit differently here than it has been in any other rocks we've seen at Meridiani.

If you've been following the images closely, you've probably noticed that something pretty weird happened to our RAT hole between Sol 546 and Sol 549. The images we got on 546 were pretty nice, and they showed that we had a nice clean RAT hole, but the floor of the hole was a little bit out of focus. So before we drove away, we decided to hit it one more time, on Sol 549. Those images, though, are a mess, with lots of crud in the hole. It looks as if we had never brushed it, though we always use the RAT brushes to remove the cuttings from a hole. What happened, apparently, is that there was a pretty substantial wind event sometime between Sols 546 and 549 that blew a bunch of cuttings back into the hole. So the 546 images are the best that we're going to get for this hole... that's life. And while this wind blast had quite an effect at ground level, it doesn't seem to have done much for Opportunity's solar arrays. That's okay, though, since we're currently in pretty good shape power-wise.

Opportunity has moved on, and we're now parked at what could turn out to be one of the more scientifically important spots that we've encountered in quite awhile. One mystery we've been dealing with for a long time is the origin of the little dark "cobbles" that we occasionally see out on the plains. There are two theories. One is that they're pieces of ejecta... stuff that has been thrown out of nearby craters by impacts. If so, that's really interesting, since they're clearly made of something different from the blueberry-laden sulfates we see everywhere. If they're ejecta, then presumably they're pieces of whatever lies below the blueberry-laden sulfates, which is a material we've never seen.

The other theory is that they're meteorites. That'd be interesting too, though it'd tell us less about Mars than if they're martian rocks. Both theories make sense, and both have precedents... Bounce Rock, which we found just outside of Eagle Crater, was a piece of ejecta from a crater pretty far away. Heat Shield Rock, which we found just south of Endurance, was a meteorite.

Opportunity is parked right in front of a field of cobbles now, and we're spending the weekend taking APXS and Moessbauer data on a couple of them. So we should know soon enough.

The other puzzle we may be able to go after here are the mysterious "rinds" that we sometimes see on rocks at Meridiani. These look like hard outer shells on some parts of some outcrops, and they're darker and a little redder than the rock that they encrust. The outcrop right in front of Opportunity now has some beautiful rinds on it, among the best we've ever seen. So once we nail the cobble problem, we may go after the rinds next.

Over at Gusev, Spirit is on the move. We're done with our work in the Voltaire region, having just finished up a pretty thorough IDD investigation of a rock called Assemblee. This thing turned out to have a crazy composition, with by far the highest levels of chromium that we've ever seen on Mars. A weird one. So now we're headed toward the summit, and as I write this on Sunday afternoon we just finished a beautiful drive of something more than thirty meters. The end-of-drive Navcams from Sol 573 show a feature on the skyline that's either the summit or something very close to it. I think we're going to make it.

August 7, 2005 (later the same day)

Well, that's what I get for making a prediction! We've really dug into the APXS data from Assemblee over the past few hours, and it turns out that it has very little iron in it. It's like Independence in that respect, though it's quite different from Independence in others. Anyway, low iron is interesting, but it means a weak Moessbauer signal. So we now expect that the only way we can get a really good Moessbauer measurement on Assemblee may be to leave the instrument in place for two more sols, rather than heading toward the summit on Monday. We'll decide first thing tomorrow morning what we're actually going to do. Never a dull moment...

August 7, 2005

It'll have to be a quick one this week.

Spirit is just wrapping up work in the Voltaire region. We gave Voltaire the full treatment with all of the arm instruments at Bourgeoisie, and then we took a bunch of MI images of a rock right next door named Hausmann. Great stuff... rounded to angular pebbles embedded in a very fine-grained matrix. There's a chance this stuff is what you'd call an "impact breccia": the jumbled up debris thrown out from a high-velocity impact. But we're looking at a few other options as well. After Hausmann we moved on to Assemblee, another rock a few meters away that looked unusual to Mini-TES. We're collecting Moessbauer data on Assemblee as I write this, and we've just gotten down some very interesting APXS data and MI images. The MI images (which should be on the web pretty soon) show more small pebbles embedded in fine-grained matrix, but the APXS data look different from anything we've ever seen before. We'll be very interested in what the Moessbauer has to say about Hausmann.

Starting Monday, we'll be making our move toward the summit. This will go more slowly than we'd like, since we're in restricted sols with Spirit now... so for awhile we'll only be able to drive every other sol. But each drive will take us closer to the top, and closer to what we're all waiting for... that view down the south side of Husband Hill.

At Meridiani, Opportunity is on bedrock! It's the first bedrock that we've seen up close on that side of the planet in months, and it feels very good. We've just put in our first RAT hole in a very long time, and we'll be studying it for a little while before moving on.

With all this bedrock around us now, we've suddenly got a very long to-do list with Opportunity. Has the bedrock changed in chemistry since Vostok (which was the last place we saw rock)? Has it changed in mineralogy? What kind of layering do we see here? How did all of these polygonal fractures that we see in the rocks form?

And here's a big one: What is the composition of all those loose pebbles or cobbles we see lying around? We've been wondering about this one forever. Are they just pieces of sulfate-rich rock? Are they pieces of something different that's been excavated from deep below the surface... a rock unit we've never seen before? Or are they little pieces of meteorite? There's a lot of this stuff lying around here, and we're going to try to nail this question pretty soon.

So I'm not sure when we'll get to Erebus... there's so much new science right around us that we're not in a big hurry. We've been starving for a long time, and suddenly we've got a feast in front of us.

And I suppose that the biggest news of all is simply that there's so much bedrock here. Our fear as we approached the bright materials in the etched terrain was that it wouldn't be rock at all... that it'd simply be dust that would make our route southward tedious at best and impassable at worst. But it's not dust, it's rock. And now we believe that all the bright stuff to the south of us is rock as well. The etched terrain isn't going to be easy to get through, but it's not going to be the impossible quagmire that we had feared it might be. So southward we go... once we get a little science done.