(Return to archived mission updates list)
June 29, 2005
It's been an uncommonly good week so far for both rovers. It's funny with
these vehicles... we have some stretches of time where it seems
happens, or where various frustrating little glitches slow
us down in some way or another. And then we'll have other
where everything seems to work exactly the way we want it to.
This week has been one of the latter ones.
Our drive last weekend with Opportunity was perfect, and it put the
part of Purgatory Dune that we wanted to study right into the
arm's "work volume" -- the territory that the arm can reach.
We then developed a very aggressive three-sol plan to
learn everything we can about the dune: Microscopic Imager,
APXS and Moessbauer in the old wheel tracks,
MI and APXS out on the surface next to the tracks so we
have something to compare it to, and Mini-TES to tell us
about the thermal inertia of the soil. We're two sols into our
three-sol campaign now, and so far it's gone perfectly.
I wish I could really describe here the great job
the Opportunity engineering team has done this week, managing power
down to a tenth of an amp-hour each sol so we can squeeze
every available drop of science out of the vehicle.
The sol we planned today will wrap it up, and the sol we're
plan tomorrow will be the one we've waited two months
for... driving away from Purgatory Dune.
So, if you're watching our images, in another few days
you'll see Opportunity on the move again, at long last. And if you
watch closely, you'll see something that might freak you
out a little... we'll be driving north.
No, we haven't decided to turn tail and run away from
Erebus Crater! But after a careful study of all the
images we have, we've concluded that the best way to
map a path to the south is to start by going north a
little bit, and taking some pictures off toward both the
east and the west. Those images will complement ones
we have already, and should allow us to plan the best
possible southward path. So there'll be two or three drives to
the north first, a lot of imaging, and then the long
hard push south toward Erebus.
Over at Gusev, Spirit continues to shine. We've been really
nailing our drives there lately. It hasn't hurt that the
recent terrain has been just about the firmest ground we've
seen anywhere at Gusev crater. We don't really understand
this, frankly, but if you look at recent Hazcam and
Navcam images you'll see that we're barely even leaving
tracks, the ground is so hard. It makes for great
traction and great climbing. I'm still not confident
that we'll make it to the summit, since the images seem
to show a transition to softer ground with more loose
rocks ahead. But we're enjoying the conditions while we've
And to make things even better, we seem to have found
a nice piece of layered bedrock. This turned up right
underneath the rover early this week after one of our
long drives, and the timing was perfect. We've named
it "Independence Rock", and we've maneuvered into
position on it to do some arm work over the coming
holiday weekend. We like to try to give the operations
team a few days off on holidays, but of course we
need to keep the rovers busy every sol. If we're
trying to drive every sol we need to come to work and
plan every day, since the terrain around the rover
is always new and different. But when we're going
to be parked in one place for several sols, we can
plan multiple sols in advance and give people a little
time off. So the Spirit team
planned three sols yesterday and will be planning
three more tomorrow, giving everybody on Earth the
holiday off but keeping Spirit busy looking
Of course we're dying to know what Independence really
is. We haven't seen any MI images of it yet, but in the Pancam
images it's finely layered, with a strange kind of
porous texture. It looks a bit like Peace and
Alligator, and a bit like Methuselah. Methuselah was
one of the many high-titanium, high-phosphorous, low-chromium
outcrops we saw all over the place on Cumberland Ridge,
and Peace and Alligator were a couple of very weird sulfate-rich
outcrops that we found our climb up to Larry's Lookout.
I've felt all along that Peace and Alligator were probably the
most important rocks we've found at Gusev, and it would
be very cool to find another one like them.
If I had to bet money I'd
bet that Independence is
similar to Methuselah, but I've been fooled
by Mars so many times now that I think it's better not to make any
bets. We'll find out very soon. And then it'll be
time to resume the climb.
June 25, 2005
It's been slow going at Meridiani lately. We need to take a good hard
look at Purgatory Dune with the instrument arm, but we've also got to
show this dune a lot of respect... it got us once, and we don't want
it to get us again. So as we're maneuvering into position on it, we're
using a great deal of caution.
There are dozens of safety checks we can use when we operate these
rovers. We can turn slip checking on, and we can abort a drive if
we see more slip than we want. We can monitor the rover tilt, or
the angles in the suspension system, or wheel currents, or you
name it... and abort a drive if we don't like what we see. The
big question in a situation like this is how tightly -- i.e., how
conservatively -- we should set our limits. Do you abort a drive
if you see more than 50% slip? Or 30%? or 20%? What about
tilt, what about motor current? We've got most of our safeguards
on as we approach Purgatory, and we've been setting the limits
very conservatively, to make sure we keep the vehicle safe
in this treacherous terrain.
Of course, the unavoidable consequence of staying safe in a
situation like this is that you also tend to go slowly...
occasionally tripping one of the limits and aborting a drive.
That has happened to us a couple of times recently, and we're
still a few tens of centimeters short now of the place where
we want to do the arm work. We're commanding another drive
over this weekend, and we'll see on Monday where it puts us.
Once we finally are in position, we're going to bang out the arm
work as quickly as we can, and then be on our way. It'll
feel very good finally to be moving again.
At Gusev, we're really moving... and it feels very good!
Our journey to the south side of Husband Hill is well under
way now. We've been
spiraling up and around the west side of the hill, heading
generally south and gaining elevation as we go. I've
been surprised, as I think the whole team has, at how well this
part of the climb has gone so far. Other parts of Husband
Hill have been very tough going, but for some reason we're
moving over this part of the hill very well. We've
knocked off several drives of 20+ meters lately, which
is really good for this kind of terrain, and there was
one drive where we gained about three meters in elevation.
Our drive paths have been nearly straight south lately,
but now we're starting to curl around toward the east,
more in the direction of the summit.
So now there are two big questions: Are we really going to go for
the summit? And what will we see once we get our first
good view to the south?
I really don't know about the summit. We all want it, of
course... who wouldn't? We're doing the first mountaineering
on another planet, and it would be a little frustrating fto get this
close and not make it to the top. (I'm a climber when I'm not
doing science, and Chris Leger, who has been the lead rover driver
for Spirit much of the time lately is a really accomplished
rock climber... so we both want this thing.)
Mountaineering is not the point of this mission, obviously!
We're here to do science, and we're only going to go to the summit
if it makes sense scientifically. But there's a good
chance that it will. The summit is directly between us and the terrain
to the south that we want to explore, so going over the
top may be a pretty efficient route to the good stuff. Also,
the summit really is going to offer a pretty good view. Geologists
in the field routinely climb to the top of the highest
hill to get a good look at their surroundings and plan
what they're going to do next, and we may want to do that
here as well.
What it ultimately comes down to, I guess, is how hard the
climb is. If we can get on top without wasting a lot of
sols on our trek to the south, then we're definitely going
to do it. But if we find the climbing is too hard and there's
a significantly faster route to the south side, then we'll
do that instead. So I simply don't know what's going to happen.
But for now the going is good, so it's east, up, and we'll
just take it sol by sol.
And then what will we see? We don't really know. The
views toward the south right now are enticing, but so
far we haven't seen much that we hadn't already
seen before, albeit from a lower elevation. Orbital
images of the south side of Husband Hill show some
terrace-like structures that might be exposed layers,
so those may be a major target once we get over there.
There's also a big dark area that we think is probably a
dune field, as many dark splotches on Mars are. And
there are other features that we're simply not going to
understand until we get a good look at them. The
downhill run into the Inner Basin should in principle
go pretty quickly once we start on it, but it gets
very steep in places, so we're going to have to be
careful. Anyway, we've got interesting times ahead, and
everybody on the team is pretty pumped up right now.
June 15, 2005
Spirit's on the move. We've finished up our work in the whole
Larry's Lookout/Jibsheet/Methuselah region and begun the long
climb up and around to the south side of Husband Hill.
Our last big activity before we left was to check out the rock
we named Backstay. This turned out really well, and it was a
great example of how this machine works. First we used
Pancam to survey the whole scene around the rover and figure
out what was where. That showed us where Backstay was and
what it looked like. Next we used Mini-TES to check out
a lot of the interesting-looking rocks in the Pancam scene,
to get a handle on what they
might be made of. That gave us a hint that Backstay might
be something new, and made us decide to go after it.
Then we used the rover's mobility system
to drive over to Backstay and put it within reach of the arm.
After that we used the RAT to clean off the rock's surface,
followed by MI, APXS and Moessbauer on it to see
what it was really like. And the answer, to everyone's
delight (particularly the Mini-TES guys, who had been the
advocates for going to Backstay in the first place) was that it is indeed
a martian rock type that we'd never seen before.
It's a basalt, as you might guess just from looking at the
pictures, but one with more titanium, more aluminum, less
iron and more potassium in it than the basalts we saw out on
the plains. We can't tell where it came from, of course,
since it's probably a piece of impact ejecta, and maybe one
that's pretty far from home. But it's definitely something
new and interesting for the geochemists to puzzle over.
And with that, we're off into unknown territory once more.
It really does feel good to be on the road again. (In fact,
somebody put up a picture of Willie Nelson at today's
Spirit SOWG meeting just for that reason!)
The current plan is pretty much just
drive-drive-drive for awhile unless something interesting
and unexpected pops up in the images. So look for nice new
vistas to the south as we work our way around the hill.
Good progress too at Meridiani, though we're being slowed down
a bit right now by being in the period we call "restricted
sols". This is what happens when Earth time and Mars time
line up inconveniently, so that we have to plan each sol
on the basis of what happened on Mars not yestersol, but the sol
before. Despite being in restricted sols, we've gotten Opportunity
through most of the three-point turn we're using to get her
facing back toward Purgatory Dune. The next step will
be to get into a safe position on the dune to try some
arm work on it before we move on.
And dust is down a little at both sites, and Mini-TES on Opportunty
seems happy and healthy. So life is good.
June 11, 2005
We've had a good weekend so far at Meridiani. Our objective at the
moment is to turn Opportunity around so that we can safely approach
Purgatory Dune and investigate it with the instrument arm and with
our Mini-TES instrument. Rather than do a 180-degree turn in place --
which is possible but a little funky with a stuck right front steering
actuator -- we're doing a three-point turn instead. We're
partway through it now, and it's going really well... there has
been very little slip, and much of the fine-grained debris
that had been adhering loosely to the wheels has now fallen
off. So we're very pleased with the progress so far. More
progress should follow shortly.
So wait a minute, you may be thinking... Mini-TES? Wasn't the
Mini-TES instrument on Opportunity malfunctioning? You may recall
that the Mini-TES on Opportunity wasn't working properly
presumably due to the dangerously cold temperatures it sees
each time we use Deep Sleep. But we've been keeping an eye
on Mini-TES, and the last few times we've used it, the thing has
worked just fine. Something's wrong inside the instrument,
but whatever it is,
the problem is an intermittent one, and right now the instrument
seems to be okay. We're confident that
using the instrument won't make matters worse, and in a situation
like that the thing to do is to use it... aggressively. So for
now the Opportunity Mini-TES is back in business. We'll see
And in the "it's always something" department... we are now
facing a new threat to both vehicles. It is dust storm
season on Mars. Dust storm season happens once per martian
year, during the southern summer when the input of solar energy
into the martian atmosphere is highest. And southern summer is
now upon us. The atmospheric
dust levels at both of our landing sites are
high and climbing, and in fact the dust level at the Opportunity
site is the highest we've ever encountered. It's not a
serious threat yet, but it's a worry, and we're watching the
dust levels in the atmosphere very closely.
The thing to realize about dust storms is that the threat is
not high winds, nor is the primary threat dust buildup on
arrays. Instead, the primary threat is simply the attenuation of
sunlight by dust that is suspended very high in the atmosphere,
and the resultant loss of power
from our solar arrays. RIght now we've got power to spare on
both vehicles, and there is no imminent danger. But martian
dust storms are notoriously hard to predict. In some years
things are pretty quiet, and in other years what starts out
as a small regional storm can blow up quickly into a monster
that covers the whole planet, with solar attenuation that could
be very bad for our vehicles. We have no way of knowing
what's going to
happen this year.
With both vehicles in such good shape, and with the solar arrays
as clean as they are at the moment, we can handle a lot of
atmospheric dust and come through it okay. And even if things
do get very bad, there are a number of tricks we can use to
save power and ride it out until the atmosphere clears. Still,
we've learned that exploring Mars involves nearly constant peril, and
dust storm season is looming as the next
significant peril we may have to face.
June 9, 2005
Today is something of a landmark for us. As of the end of today's
MER-B Command Approval Meeting, which will take place late this
evening on the west coast of the US, and probably close to midnight
here on the east coast, we will have planned one thousand sols
on the surface of
Mars... 490 for Opportunity and 510 for Spirit.
The uplink process for these vehicles is intense, engrossing and
exhausting. At some point I probably should sit down and describe
it in these pages. For today, though, I'll just tip my hat to all
of my friends, colleagues and comrades -- engineer and scientist
alike -- on the MER uplink team. 1000 sols is a remarkable accomplishment.
Good things are happening on both sides of the planet. At Meridiani,
we'll soon begin our first maneuvers to reorient the rover so that
we can study the feature that got us and then be on our way again.
And the feature that got us now has a name: Purgatory Dune. We
weren't calling it anything back when we were stuck in it, but
now that we're out, it seemed there ought to be a name for
At Gusev, Spirit is parked at Backstay and crankin' away.
Once we're done with Backstay, we're going to do a quick
drive-by of Methuselah to get a little more imaging on it
that'll help tell us which way the rocks are tilting. And
with that done we'll be ready to move on.
If you've been reading these pages, you'll note that I haven't
said yet where we're going after Methuselah. I wasn't playing
games... the reality was that we hadn't decided. It's a
much tougher call than you might think, because there are some
very interesting outcrops down in Tennessee Valley, and some
really good-looking stuff on the far wall of the valley.
But after a lot of thought we have finally decided, and the
decision is to head up Husband Hill. We're not going to try
a frontal assault this time. Instead, we're going to spiral
up and to the right, working both upslope and also cross-slope
Whether we'll actually reach the summit is an open question
at this point. But we're convinced that the route we've
chosen offers the quickest path to a view of whatever's
on the south side of the hill... and that's what we want
to see next.
June 4, 2005
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 rear 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
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
moving on to anything new.
Time to go celebrate...
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 this
would happen but still... what a relief!
June 2, 2005
Steady progress on both sides of the planet.
At Meridiani, we've picked up the tempo a little bit. On each of
the last two sols we've commanded 20 meters worth of wheel turns,
and on each we've seen about 12 cm worth of motion. That's encouraging; it's
a rate of progress at or above anything we've seen so far. Perhaps
more significantly, we're starting to see some changes in the
geometry of the rover's suspension that suggest that we're
making real progress over the crest of the ripple, which we
were straddling back when all this started. The right rear
wheel is starting to come up now with respect to other parts of the
means that the right middle wheel (which we can't see) has
to be going down. And if the right middle wheel is going
down, that probably means that it has crossed the crest of
the ripple and is starting to go down the other side.
I'm still not ready to guess when we'll be on our
way again, but it's really heartening to see the kinds of
changes that we knew we'd need to see before we could get
Over at Gusev, we've finished up our work on Larry's Lookout.
In fact, we've only got a few odds and ends to tie off now
before we leave this region for good. The most important of
those will be to motor back toward Methuselah and get one
more set of Pancam images there, aimed primarily at allowing
us to make some fairly precise calculations of the orientation of the
layering... what geologists call strike and dip.
Once that's done, we'll be ready to leave the whole
Lookout/Jibsheet/Methuselah region behind, and strike out
toward new territory.