Week Ending March 30, 2002
We had a real good week, for a change. The first piece of good
news is that the Mössbauer problem
that popped up during vibration testing a couple of weeks ago is
easy to fix. Bodo and Goestar have already fixed the one broken
instrument in Germany, and the next time they come over they're
going to apply the same fix to the two good instruments already
at JPL, just to be on the safe side.
The second piece of good news is that our second Mini-TES is now officially delivered to
JPL. If you're keeping score, that's three and a half of our
twelve payload elements delivered (two Mini-TESes and one
and a half Moessbauers -- we've delivered two Moessbauer sensor
heads, but only one of the electronics boards). Lots more to
Week Ending March 23, 2002
Our landing site situation just changed again. Sometime in the next couple
of months we were due to recommend our two final landing site choices to
NASA. But now we've had a delay, and for once a delay in our schedule is
a good thing.
The longer we can wait to pick our landing sites, the more we'll know
about Mars. The Mars
Odyssey spacecraft is just beginning to collect data at Mars, and
it has started to return some fantastic new data for some of our
possible sites. There has been very little time to study the data,
and there's much more data to be taken. So if we can give Odyssey some
more time, we'll know a lot more about Mars when the time comes to
And it turns out that we have some more time. For months we have
been very worried that the mass of our spacecraft might be too
high. But lately, as we have gotten more and more hardware built and
weighed, that has become less of a worry. So with a little breathing
room now, we've realized we can add a little bit more rocket fuel
to the design. And with that extra fuel aboard, we can now target each
spacecraft to land just about anywhere we want on the planet. The bottom
line is that instead of having to pick our sites soon and stick with
them, we've got almost another whole year before we have to make up
Week Ending March 16, 2002
This was Mössbauer week at
JPL, and it was pretty wild. Goestar and Bodo brought over the
sensor heads for both instruments. (The sensor head is the part
that goes out on the rover's arm.) The big job for the week was
to put them through vibration tests that simulate a rocket
launch, and other tests that simulate the jolt of an airbag
landing on Mars.
These tests are quite something to watch. It's a lot like what
they say about being a pilot: hours of boredom interspersed with
moments of sheer terror. The hours of boredom are all the work
of setting up for each test, and the moments of sheer terror come
when your precious hardware gets subjected to such violent
The uncanny thing about a vibration test is how much it sounds
like a rocket launch. Of course, that makes perfect sense when
you think about it. The vibration facility is really nothing other
than a gigantic loudspeaker, and the electronics that make it work
are nothing other than a gigantic synthesizer. And the song that the
synthesizer was playing last week was simply the sound of a Delta
rocket heading for space.
We passed nearly all of the tests. Both instruments passed the
landing test, and one of them passed the vibration test. The other
one had an electronics board that wasn't quite fastened down
right, and it shook loose during vibe. This is why you do tests!
We'll fix it up and test it again in a few weeks.
Week Ending March 9, 2002
It's crunch time for the Mössbauer
Spectrometer. The nasty "ringing" problem we had last week has
definitely been solved, so it looks like we dodged that bullet. The
latest problem is that one of the Mössbauer electronics boards -- the
part of the instrument that lives inside the rover body -- is getting
a little flakey on us when we run it at cold temperatures. It doesn't
look like a serious problem, but it's going to take a little time
to fix it.
The Mössbauer sensor heads, though -- the parts that go out at the
end of the rover's arm -- are ready to go. So we're going to deliver
the instruments to JPL in two parts. This week Goestar is going to
come over from Germany with the sensor heads, and spend the week at
JPL putting them through a bunch of tests. We're going to shake them
as hard as they'll be shaken during launch, whack them as hard as
they'll get whacked when we land, vibrate them like they'll vibrate
when the RAT is working, and so on.
And once that's done, the sensor heads will be officially ready to
go to Mars. Meanwhile, back in Germany, the rest of the guys will be
running down the last of the electronics problems. So then, a few
weeks from now, we'll get to do the same thing all over again with
the electronics boards.
Week Ending March 2, 2002
We had what looked like a pretty serious problem with our
this week. We're now doing thermal testing, which means making sure
that the instruments work properly at the temperatures that we'll
actually see on Mars. The Mössbauers were behaving fine at
room temperature, but when they got cold they started doing
what we call "ringing". Each Mössbauer has a little drive
system inside it that vibrates back and forth about 20 times a
second. It's supposed to vibrate in a controlled way, but when
it "rings" it's sort of like what happens when you put a microphone
near a speaker and get feedback... it vibrates out of control.
And if that happens, we don't get Mössbauer data.
At mid-week it looked like we might have a pretty bad problem,
but the guys in Germany -- Goestar and Bodo and Daniel -- have
really hunkered down and worked hard on it over the past few
days and nights. They traced the problem to one part in the
electronics, and with a change to that part one of the two
instruments is now behaving itself down to temperatures as cold
as -120 C. We still have to finish the testing and then fix the
other one (once everybody catches up on some sleep!), but right
now things are looking pretty good.
Week Ending February 23, 2002
This is it. On Monday, February 25th, we're about to begin ATLO:
Assembly, Test, and Launch Operations for the rovers.
Every space project has several critical phases in its life,
and ATLO is one of them. ATLO is the process of actually
putting the flight hardware together, making sure it works,
and shooting it off to wherever it's going. For us, ATLO
It's a funny feeling. On the one hand, we barely feel ready
for it. Time is precious, and a few more weeks to get better
prepared for a job this difficult would be nice. On the other
hand, we've been waiting for this for so many years, it feels
great to finally be doing it! These rovers have been in the
planning stages -- and have been at the very center of our
professional lives -- for more than six years now. And seeing
the real flight hardware finally start coming together after
all that time is a thrill that far outweighs whatever
nervousness we might have.
Week Ending February 16, 2002
Our schedule is so tight that even minor delays seem major, and
we had a bunch of them this week. The camera electronics got
set back a week because one of the cables in the design was bent
a little more sharply than it ought to be, meaning that we had
to change things once again to fix it. There's a minor problem with
noise in the APXS electronics that's
had everybody working crazy hours in Germany. And for some weird
reason we've been having a terrible time lately just trying to
ship stuff around. Electronics parts are "in the mail" for what
seems like forever on their way to Mainz. Magnets on their way
from Copenhagen to LA get hung up in Paris. Calibration targets
vanish for a week while being shipped between Arizona and
Colorado. It's maddening. Nothing's gotten lost permanentely,
and if time weren't so precious, stuff like this wouldn't matter
at all. In fact, the delays really haven't been all that serious.
But when something's moving as fast as this project is, it can
seem like the rest of the world is going in slow motion.
Week Ending February 9, 2002
We had a great week -- Mini-TES
2 passed its vibe test! Vibration testing is one of the crucial
events in the life of any piece of space flight hardware. You can
read more about vibe testing on our Science Bites
page. We had shaken Mini-TES
1 pretty hard some time ago, so we knew that the basic Mini-TES
design was solid. This vibe test on Mini-TES 2 was what is sometimes
called a "workmanship" test. We already knew it was designed well;
this test showed us that this particular Mini-TES is also put
together well. The guys in Santa Barbara put it through its paces
right after the vibe, and everything checked out fine.
So now it's on to the next test...
Week Ending February 2, 2002
We made a major change to our
plans this week. A few months ago,
we narrowed our choices down to just four places on Mars, and
since then all four have been under some really intense study.
Unfortunately, that study has turned up what could be a real
problem with one of them.
The one that may be dangerous is the one we call Athabasca.
It's a great site, but recently we've looked at some radar data that look really scary.
You can bounce radar signals off of Mars from Earth, and when
you do the signals that come back from Athabasca look like what
you'd expect if the surface there were really rough.
Not only that, but the roughness seems to be just about the
same size as our wheels are. That's not good!
To be honest, we're not 100% certain what the radar data really
mean, and we can't prove beyond a shadow of a doubt that Athabasca's
not perfectly safe. But it looks scary, and we're not about to
take any big chances with these rovers. So Athabasca is off the
list, and we've replaced it with a site in a place called
Isidis. We still have several
months before we have to pick the final two sites, and the work
Week Ending January 26, 2002
Murphy's Law seems to be one of the guiding principles behind space
missions, but every now and then something goes right. We had two
of 'em this week.
Several weeks ago, we discovered that we had a problem with
Mini-TES number two. The
instrument worked fine in most ways, but the results we were
getting were more "noisy" than they should have been... a little
like too much static in a TV picture. The guys in Santa Barbara
tracked this one down and thought that they had fixed it. We
did some tests last week, and it turns out that they did more
than just fix it... Mini-TES 2 is now even less noisy than
Mini-TES 1 is.
The other one had to do with our cameras. For a couple of months
now we've been wrestling with a problem where the voltage of
the electrical power delivered to the cameras wasn't coming out
quite right. We found a fix, but it didn't look like a very
elegant one. Even though it clearly would work, it looked like
it could really increase the amount of power it would take to
run each camera. And electrical power is really precious on
a solar-powered rover! The JPL electronics guys have worked really
hard to fix this, and this week we did some tests that showed
that in reality the power usage of the cameras will be
much lower than we had feared it would be... which
means we can use that extra power to take more pictures.
So this week was a combination of some great design work and a
little bit of luck. Occasionally things go your way.
Week Ending January 19, 2002
It's always something. This week we discovered another one of those
dumb mistakes that could really have gotten us into trouble us if we
hadn't caught it now.
One of the things we have to be very careful about is what's called
"Planetary Protection." For us, Planetary Protection means not
contaminating the surface of Mars with bacteria from Earth. There
are all kinds of good reasons to be careful about this!
One way to do Planetary Protection is to sterilize the hardware
we fly, and we do that with much of what we build. But some things,
like electronics, are not easy to sterilize. So the other thing we
do sometimes is clean our hardware carefully, and then seal it up
really tight so nothing bad can possibly get out.
Of course, it's not that simple. Everything is full of air when
we launch from Florida, and the air has to get out as we
ascend into space. We can't let any bacteria leak out with the
air, so we put special filters in place that let the air out
while keeping the bugs in. And it all works really well.
But there's a problem, as we just learned: These filters don't
just let air through them... they can also let light through them.
And we have them in our cameras! Let extra light leak into a camera,
and you can take some very bad pictures.
So now we're designing little "hats" to go over the filters. Air
can still get out, but light can't get in. Problem solved.
But like I said, it's always something...
Week Ending January 12, 2002
The whole project is about to shift gears pretty soon, in a very big
way. In only about a month, we start what's called "ATLO"... short for
"Assembly, Test, and Launch Operations". ATLO is NASA-ese for the
process of putting it together, making sure it works, and shooting
And that's what we're about to start doing. For a very long time now
we've been planning, designing, and building bits and pieces of things.
The planning is finished, the design is all done, and lots of bits
and pieces are built. So starting next month, we begin to put it all
This shift to the start of ATLO is one of the biggest changes that
a space project goes through, so of course we have to have another
review before we do it! Next up is our "ATLO Readiness Review", where
we try to convince a review board (and ourselves) that we're ready
to get on with it. The past week has mostly been spent getting ready
for this review, and the next one will as well.
After all these years, it's going to feel good to start actually
building these things.
Week Ending January 5, 2002
We've got an awful lot of testing to do, but sometimes real-world problems
get in the way. This was supposed to be the week that we were going to
do some important
vibration testing on our
Mössbauer spectrometer. It didn't work out that way. Everything needs
maintenance and refurbishment from time to time, including vibration
test facilities. We've had to postpone tests that we were ready for
a couple of times recently because the test facilities weren't ready for
us. It's easy to get a little impatient when this happens. But that's
why we've got margin in our schedule!