(Return to archived mission updates list)
October 24, 2005
Opportunity was the star of the show this week. One piece of news, of course,
is that we're really driving again. Erebus is a nasty place to work, with
widely-separated outcrops of rock separated by lots of dunes and drifts,
some of which look like they could be
real rover-eaters. But we're getting the hang
of driving in this stuff, and we made some very solid progress toward
the Mogollon Rim this past week.
On top of that, Opportunity has stumbled onto something really new and
different lately... the blueberries seem to be gone! We've been seeing
smaller and smaller berries in the rocks since all the way back at
Strawberry and Lemon Rind, two of the rocks we looked at before we
got on the Erebus Highway. So we've known something was going on
for awhile. But if you look at the most recent images --
the front Hazcams from Sol 617 are a great example -- you'll see that
the rocks here appear to be lacking berries altogether. We can't say
that they're gone completely... we really need some better imaging,
including MI images, to do that. But this sure doesn't look
anything like the berry population back at Eagle or Endurance.
We haven't done any IDD work on this stuff yet, but that'll be
coming soon. And it's such a new discovery that it's too early yet to
say exactly what it means. But one possible guess at this point is
that we have moved "up section" in geologic terms -- to rocks
that are higher up in this stack of layered sediments -- and that
the rocks at this level never experienced the concretion-forming
process. It's an interesting hypothesis with interesting implications,
and it's also one that could explain a few other odd things we've
been thinking about ever since Eagle crater. We're not jumping to
any conclusions, but everybody is itching to get the IDD onto this
stuff as soon as we get the chance.
At Gusev, Spirit is working her way nicely down the upper portion
of Haskin Ridge. We're within a few tens of meters of the top of
the step now, and we've stopped for a bit of IDD work on a new
outcrop called Kansas. No idea what it's made of yet, but we should
get some clues over the next couple of days.
October 16, 2005
It's been ten days of high drama on the Spirit side of the planet.
As we were completing the Everest pan, we decided that the one thing we
still had to do before leaving the summit was some IDD work on Hillary.
Easier said than done, it turns out. What was happening
on Mars may have looked fairly benign
as the Hazcam images were coming down, but this IDD campaign was
one of the hairier things we've ever tried with either rover.
The initial approach wasn't too bad. We were on familiar ground, and the
rover planners managed to put Hillary within reach of the
arm with just a couple of very sweet drives down off the summit. But
our position at the end of that second drive looked pretty dodgy: A
very steep slope (we were pitched up more than 27 degrees) and some
very loose-looking crud under the wheels.
In a position like this, nobody was real comfortable about deploying
the IDD, because we had no way of knowing how stable the vehicle
was. Swinging the IDD out changes the center of gravity of the
rover, and if you're on really unstable ground that could cause
unanticipated motion of the vehicle, potentially whacking delicate
components (like the instruments on the arm) into rocks.
So, before deploying the IDD, we did a set of "wheel wiggles"...
turning the front and rear steering actuators back and forth, just
to make sure the thing had settled properly. Unfortunately, with
each wiggle, the rover moved! It shimmied back down the slope something
like 2 cm with each wiggle. A little motion isn't unexpected when
you wiggle wheels on a slope this steep, of course, but it wasn't
exactly a confidence-builder. We weren't sure whether it was safe
to put the instruments on Hillary or not.
So what to do? This was a crucial rock, and we really didn't want to
back off from it. At the same time, we had to know whether or not it
was 100% safe to put the IDD instruments onto it. The scheme we came
up with, in a very long day of planning, was to deploy the IDD
partway -- to a position where it was extended, but where there was
zero chance of the instruments touching the rock even if the rover
shifted. Then, the next morning, we'd see how much of a shift there
had been, and make a go/no-go decision regarding the actual measurements.
The go/no-go came last Saturday, with members of the team calling
in from airports, cars, everywhere (I was in my car on the way to
Boston at the time). The news was great... the rover tilted only
0.005 degrees as a result of deploying the arm, and it did not slip
by any discernable amount. So we were go for the deploy, and over the
next several days we did two detailed IDD campaigns on Hillary...
one at a spot called Khumjung and the other at a spot called
Namche Bazaar. It all worked, and we got everything we hoped for
out of it.
The science result, in a nutshell, is that the summit rocks are
nearly indistinguishable from rocks we found near Jibsheet,
hundreds of meters from here. That includes how they look, and
also what they're made of. And the rocks here are tilted
at a very different angle from the ones at Jibsheet. All in all,
it was a crucial piece of the puzzle in trying to work out the
geology of Husband Hill.
From where I sat, the Hillary campaign
was one of the MER uplink team's finest hours.
In a situation like that, perched on loose ground at a 27-degree
angle, at the summit of a mountain on Mars, we're right at the
ragged edge of the vehicle's performance capability. The
team thought it through carefully, kept the vehicle safe, got the science,
and in the process nudged outward the performance envelope of
what you can achieve with a robot on another planet. It was
a pretty cool thing to watch.
So now we're on our way again, starting the descent of Haskin
Ridge. The first move was a very nice, pulling back
from Hillary, shooting a little more data on it, and then
driving 41 meters to the east. We're on new ground now, and
we're going to be seeing some new sights. Spirit has really been
on a roll lately.
Unfortunately, it was a week of frustration over on the
Opportunity side of Mars. You get good luck and bad luck in
this game, just like anything else, and we've had more than our
share of bad luck at Meridiani lately.
First there was the unexpected drive partway into something
we called Telluride Dune, a little drift that was nasty enough
that it triggered our slip-check alarm and stopped a drive. Fair
enough; that's the way things are supposed to work when the
going gets dangerous in this kind of terrain. No sooner did we
back out of that, though, than we got hit by another of the mystery
reboots that Opportunity has encountered a few times in the
past several months. This was different from what hit us on Sol 596...
that one we understand and can trace to a simple bug in the
software. But this one we don't understand yet, and it
cost us a couple more sols. And then, just as soon as we
recovered from that, we had a minor problem at one of the Deep
Space Network stations and lost two more sols. Not
a good week.
Each event was benign individually, and each was unrelated to the
others. So it really was nothing other than a run of bad luck, for a
rover that's had more than its share of good luck. Still,
the end result was a week in which we made zero progress toward
the Mogollon Rim, so we're going to try to really get things
moving in the week ahead. One good piece of news is that this
latest mystery reboot was almost identical to one that happened
a couple of months ago... and somewhere in that fact may lie the
clue that'll help us figure it out. The reboots do no harm
to the vehicle, and we've gotten very good at recovering from
them. But they cost us sols when they happen, and that's never
a good thing. So we're working hard on this one.
October 4, 2005
Sorry it's been a little longer than usual since I've done one of these... we
had a server down for a couple of days.
Spirit's doing well. The big event of the past week, of course, was that we
finally reached the true summit of Husband Hill. There are several rocks
up here that we've had our eyes on for possible IDD work, including ones
named Whittaker, Tenzing and Hillary. But first we had to climb to the
highest point on the hill, to get the lay of the land around us and to
take some images that'll let us determine the tilt (what geologists
call "strike and dip") of the layers in the summit rocks. And rather
than name the single highest rock on the hill after any particular
mountaineer, we simply called it "Everest".
So that's it for the mountaineering names.
Don't ask me what names we'll use if we ever get to the summit of McCool Hill!
While we were on top, it made sense to bang out one more
big Pancam panorama... which we called the "Everest Pan". It's coming
down now, and it's going to be quite a picture once it's all stitched
Having looked at all the summit rocks, the one that we like best for
IDD work is definitely Hillary. So right now we're driving back
around to the face of Hillary for what should be a pretty solid IDD
campaign there. And with that, the summit campaign on Husband Hill should
be done, unless something unexpected pops up.
The seasons are changing, and it's time to get a move on.
The big news, I guess, is that we've decided where we're going to
go next. We've been studying possible descent routes for a couple
of weeks now, and we've settled on one, at least for the first
part of the descent.
Extending eastward from the summit of Husband Hill is a broad
ridge that we've named Haskin Ridge. It trends ENE from the
summit, does a little dog-leg to the right, and then trends
ESE for a bit. Right at the dog-leg there's a pretty steep
step, which we're not certain we can get down. So we're going
to descend the upper portion of the ridge, right to where
the step is, and assess the situation. If we can see a safe
route, then we'll continue down onto the lower portion of
Haskin Ridge. If not, then we'll think about what to do next!
But either way, we should get a good view of the East Basin, which
is something of a mystery at the moment. And we all think our
chances of finding a way down that step are pretty good.
If we can get down onto the lower part of the
ridge, we'll eventually hang a hard right turn and head south,
toward Home Plate, crossing some interesting-looking terraces
and passing just to the east of a dark patch of sand as we do.
But that's for the future. Right now our
focus is upper Haskin Ridge, and whatever the view is going
to be from the top of that step.
I should also mention that we've just given some interesting names to
the rocks just east of the summit: names like "Montagsdemo",
"Nikolaikirche" and "Wiedervereinigung". Yesterday was the
Tag der Deutschen Einheit (German Unity Day), celebrating the
re-unification of Germany. We have a lot of German scientists
on our team, and two of our instruments -- the Moessbauer
Spectrometer and the APXS -- came from Germany. So to celebrate
we gave a number of rocks names inspired by German
re-unification. You can find more information
Over at Meridiani, Opportunity is doing fine. She gave us a little
bit of a scare a week or so ago, returning no data at all for 24
hours. I of course was having high-stress flashbacks to the big
anomaly we had on Sol 18 of the Spirit mission, but as it turns out
everything was just fine. What really happened was that we had been
hit again by a benign little software bug that had also given us
trouble twice before, on Spirit sols 131 and 209. This time it
hit us at just the wrong moment, the result being that we got no
data at all for a sol. We fired up a high-priority comm window
first thing in the morning (Mars time) on Sol 597 -- at about
5:00 AM on the east coast of the US -- and Opportunity woke up
smartly and greeted us with a smile. However stressed-out we were
here on Earth, on Mars things were just fine.
Sometimes I think these
rovers are smarter than we are.
So Opportunity continues westward, picking her way carefully along
the outside of Erebus crater. This is treacherous stuff we're
driving through, as a look at the Sol 603 Hazcams will show. But
we've got our driving safeguards on, and Opportunity is able now
to sense when her wheels are slipping and stop moving before we
get into another Purgatory-like predicament. It's a good thing.
As the rover moves forward, we're in the process of starting to
plan what we call the Erebus campaign. Getting some vertical rock
here would be great, if we can pull it off, and we're going to
try. But above all we want
to get past Erebus quickly and continue on our way. Victoria
crater beckons, and whether we can reach it or not, we have to