[meteorite-list] Opportunity Mars Rover Is Free!

[Ron Baalke]

http://athena.cornell.edu/news/mubss/

MER Mission Update by Steve Squyres
June 4, 2005 

We're out! The Sol 484 downlink from Opportunity just hit the ground, and all 
six wheels are on top of soil. More later when I've got some details, but I 
wanted to get the news out now while it's hot. We've been confident all along 
that thi s would happen but still... what a relief!

Boy, this has been a good day. 

We've had a feeling over the past several days that this was coming. 
On each of the last few drives, the rover slipped a little bit less 
than it had been for most of the extraction. In addition, the right 
bogey (the part of the suspension that the right middle and right 
wheels are mounted on) recently started moving in a way that 
suggested that the wheels were finally coming over the crest of the 
dune. And we knew from all our earth-based testing that when a stuck 
rover breaks free, it tends to do it very abruptly. So all the signs 
were suggesting that the big breakout was almost upon us. Still, it's 
hard to describe how good it felt to check out the downlink this 
morning and see all six wheels back on solid ground again. You develop 
pretty strong feelings for these vehicles once you've spent enough time 
with them, and when one of them gets into trouble you really sweat it 
until the trouble is over. 

So what comes next? The first thing we're going to do is simply take a 
very hard look at the stuff we were stuck in. Much of the worst terrain 
was under the belly of the rover through all of this, down where we 
couldn't see it. From our new position, everything that was under us 
for all those weeks is now visible. So we're going to take a little 
while just to look at where we were. We may also turn to take a look 
at our tracks (or trenches, or whatever you want to call them) with 
some of the instruments on the arm. But we'll see about that one... 
we'll only do it if we're convinced it's safe. 

After that -- and there is no timetable for any of this -- we will 
begin a cautious set of moves to get us on our way again. And just so 
there's no doubt about it, this little incident is not going to deter 
us from continuing our southward exploration. South is where we think 
the best science is, and we're not going to turn tail and run because 
of one unfortunate episode. Now if we find after continued driving that 
the southward road is simply impossible, then it'll be time to start 
thinking about something else. But for now, south is where we plan to go. 

And lest I forget our other baby in all the excitement... Spirit is 
doing very nicely. We were just about to hit the gas and head on out of 
here, but in the last couple of days something interesting and unexpected 
came up. Mini-TES, our infrared spectrometer, is a very nice 
compositional survey instrument. In other words, it's a tool we can use 
quickly to look around and learn something about what rocks are made of. 
We've been doing lots of Mini-TES observations on the rocks around Spirit 
for awhile now, it's gotten to the point that nearly every rock type is 
pretty familiar. But late last week, we came across a rock called Backstay 
that looks, to Mini-TES, a bit different from anything we've ever seen 
before. It's a loose rock, not bedrock, so it may be a piece of impact 
ejecta from someplace far away. The Mini-TES spectrum is nothing wildly 
exotic... the thing certainly seems to be some kind of basalt. But if 
it's a flavor of basalt we haven't seen before, then it's definitely 
worth a quick look. And luckily, a quick look is possible. Just about 
the time that we realized that Backstay was something interesting, our 
most recent drive had put us just four meters away from it. So the plan 
for the next few sols is to drive to Backstay and figure out what it is 
before moving on to anything new. 

Time to go celebrate...