Week Ending September 29, 2001
When you start testing hardware is when you start finding problems, and
we hit one this week. Believe it or not, it was with
Mini-TES, which has been the smoothest-running part
of the whole payload until now. It's a weird problem. The instrument
works fine when it's lying on its side, but goes bad when we turn it
rightside-up! The guys in Santa Barbara took it apart this week to
figure out what's wrong, and it looks like they found the problem.
It seems to be a simple one: some wires are routed wrong, in a way
that pulls the mirrors a tiny bit out of line when the instrument
is rotated. We should know for sure this week if that was the problem.
If it is it's an easy fix, but it will have taken us three weeks to
track it down and take care of it. Good thing Mini-TES was thirteen
weeks ahead of schedule before this happened!
Week Ending September 22, 2001
We're testing hardware now. It started this week, with vibration
tests on an engineering model of our APXS
instrument. An engineering model is a piece of hardware that is
pretty much identical to what we're going to fly, but that we
can test pretty severely to make sure the design is good. We took
the APXS to a test facility in Berlin this past week, and shook
in three different directions at levels more violent than anything
we should see in flight. We've still got a little more shaking
to do, but so far nothing has broken. The APXS uses a new design that
we've never tested before, so it'll be real good to have this set
of tests behind us.
Week Ending September 15, 2001
Like everyone else, our focus this week was on the tragic events
in New York, Washington and Pennsylvania. Our hearts go out to all
who suffered. We'll resume our weekly news updates next week.
Week Ending September 8, 2001
This was one of those weeks where so much was going on
that it's hard to decide what to write about. We're getting into real
hardware testing now, and things are starting to get intense. I
guess the biggest events of the week were the final preparations
for two critical tests. One is the first vibration test of our new
APXS design. In a "vibe" test,
you shake a piece of hardware to simulate the vibrations it'll
experience during launch. (Read more about this on our
science bite page.) We're going to
vibe the APXS in Berlin next week, and they're working very
hard over in Germany to get ready for it.
The other big test we prepared for this week is the first "thermal
vacuum" test of our latest Mini-TES
instrument. In a thermal vac test, you put the hardware into a
chamber with no air in it to simulate space, and then run it through
its paces at the kinds of temperatures it'll experience in flight.
This one's going to happen in Santa Barbara, and they're working
really hard there as well.
So it was a busy week. Next week should be a big one, as we run
both tests and hope that everything works.
Week Ending September 1, 2001
Our biggest problem this past week has been working out the details of how
our Pancam and
Mini-TES instruments will work together. The
Pancam cameras sit right at the top of the tall mast at the front of the
rover. The reason that the mast is so fat is that it also acts as a
periscope. Mini-TES sits down inside the rover and uses some mirrors near
the top of the mast to get almost the same view of the world that Pancam
It's that "almost" that's the problem. The Mini-TES
mirrors actually sit a little bit below the Pancam cameras, so they don't
quite have the same vantage point. Also, we couldn't get everything to fit
inside the lander until we turned the Mini-TES mirrors around so that they
look in exactly the opposite direction from Pancam. So
this means that we have to swing the mast around 180 degrees to look at
the same object with both instruments. The tricky part of all this is
building the hardware and software so that when we tell Mini-TES to look at
something that Pancam has already seen, we don't miss it, even by a little
bit. We're making progress, but this one is going to keep us busy for awhile.
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Week Ending August 25, 2001
The Critical Design Review is done. It was a long review and it made
for a long week, but we've got it behind us now. Of all the things
that we talked about at the review, the one that got the most attention
was our schedule. It's tight. Missions to the planets aren't like
other space missions. You can only launch when the alignment of the
planets is right. Miss a launch opportunity to Mars and you have to
wait 26 months for the next one. Our launches are in the summer of
2003. That's almost two years away, but two years is a very small
amount of time for all the work we need to get done. So we're going
to be watching our schedule very closely. One thing that's certain
is that the pace isn't going to ease up at all, any time between
now and the end of the mission.
Week Ending August 18, 2001
We've been having a lot of reviews lately... projects like this one
tend to attract a lot of attention! But this coming week is the
review of all reviews: the Project Critical Design Review. It
literally is the review of all our other reviews, actually. We've
had reviews of just about everything you can imagine on this
project, from some of the smallest electronic parts all the way up
to the whole spacecraft. Every piece of the payload has been through
it too, of course, most of them several times. And now it all
comes together this week at a three-day review of the whole MER
project. It's no fun... preparing for these reviews is a lot of
work. But reviewers from outside the project bring a fresh
perspective, and that means that they sometimes catch things
that we don't. Once this review is behind us, though, we've got
to really step on the gas. Assembly and test of the first
spacecraft begins in February, just five and a half months from
Week Ending August 11, 2001
We had a little bit of a scare this week. A problem popped up early
in the week that looked pretty stupid, but maybe also real. Our
payload includes several magnets,
whose job it is to gather magnetic mineral grains from the martian
atmosphere. We'll look at these minerals with the instruments,
including our Mössbauer
Spectrometer. The Mössbauer, as it turns out, is built with a
fair amount of magnetic metal in it. This metal gets attracted to
the magnet, of course, when we bring the instrument close to it.
Early in the week, some calculations suggested that the arm that
the Mössbauer is mounted on might not be strong enough to pull the
Mössbauer back off the magnet once it has touched it! Imagine going
all the way to Mars, using the Mössbauer to look at the magnet
sometime early in the mission, and then getting it stuck there.
Not good. We spent a couple of days worrying about it before
concluding that we can fix things by making a pretty simple change
in the way the arm is controlled for that one maneuver.
Week Ending August 4, 2001
Believe it or not, our biggest worry this week has been ghosts.
Or, to be more specific, we've been worried about what are called
One of the most important jobs for our Pancam camera will be to
take pictures of the sun. Part of the reason we're going to do
this is to figure out how dusty the martian atmosphere is: the
more dust there is in the sky, the darker the sun will look. The
really important reason, though, is to figure out which way is north.
Mars doesn't have a magnetic field, so we can't use a compass
to figure out directions. Instead, we use Pancam to see where
the sun is in the sky, and then use that information to work out
which way is which.
Taking pictures of the sun isn't all that hard: we just have to
give Pancam special dark filters. They're sunglasses for our
rover, really. But even with the filters, all that sunlight can
sometimes bounce around inside the camera in funny ways, creating the
"ghost images" we were worried about. But after lots of good work
by the optics experts at JPL this week, we've concluded that it
shouldn't be a problem. So we're not afraid of ghosts any more.
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Week Ending July 28, 2001
It's CDR time. CDR stands for Critical Design Review, and it's a pivotal
event in the life of any space mission. No project team does its work
without a lot of help. MER is no exception; in fact, we seem to be
getting more help than most. A Critical Design Review can be one of
the most helpful events of all. At a CDR, we bring together a panel
of outside experts, and we have them go over everything we're doing.
Their questions can cover anything from the detailed design of the
smallest component to the overall health of the project. Actually, we
don't have just one CDR, but a whole series of them, culminating in the
Flight System CDR this coming week (that's a review of the whole
spacecraft, including the instruments), and the Project CDR a couple
of weeks after that. We've spent months getting ready for this, and
we're really hoping it's going to go well.
Week Ending July 21, 2001
It's always something. We just came across a dumb little problem that
could have caused a lot of headaches in the months ahead.
There are an awful lot of cameras on this rover... ten on each. Most of
them are in pairs, but how do we keep them all straight? In going through
our documents this week, we realized that there was a lot of potential
for confusion. There's one pair of cameras on the front of the rover,
pointing forward. Another pair is on the back, pointing backward. Four
more are on top of a rotating mast. So how do we name the cameras in
each pair? Camera 1 and camera 2? If so, which is which? Port and
starboard, like on a ship? If so, then what about the ones that rotate?
It sounds trivial, but this is the kind of thing that can lead to
wiring mistakes and all kinds of other goofups if you're not careful.
We decided to keep it simple... name the cameras in each pair left and
right, as if they were eyeballs in somebody's head. That way it's
clear which is which, no matter which direction the cameras point.
So three years from now when you see a martian picture from the
rover's "Left Rear Hazcam", there shouldn't be any question about
which camera really took the picture.
Week Ending July 14, 2001
Mini-TES 2 is now a real instrument!
Well, maybe not quite, but we're getting there. We hooked the electronics
up to the optics and the motor last week.
It still has a long way to go, of course. Right now the electronics
boards are "fanned out", which means that they're hanging out where
they're easy to get to, rather than tucked neatly inside the Mini-TES
box where they belong. And we still have more pieces to put inside the
box before the instrument is really done. Most importantly, there's
enormous amount of testing that still has to happen. But what was just
a bunch of parts a few months ago is now starting to look very much
like a real scientific instrument.
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