Week Ending June 30, 2001
We've had a problem come up regarding two of our instruments: the Mössbauer Spectrometer
and the APXS. The sensor heads for both of these instruments sit right next to one another,
on the end of our instrument arm. The problem is that the Mssbauer spectrometer has a little
bit of radioactive material in it (it's cobalt-57), and the APXS electronics are sensitive to
radiation. We did a test this past week with the two instruments together, and it appears that
the APXS electronics are indeed having some radiation problems. The solution is going to be to
protect the APXS with a little bit of radiation shielding, using a material called tantalum.
Week Ending June 23, 2001
The slang that's always used in the space business to mean that you have started building some
hardware is to say that you've started "cutting metal". Well, we've started to cut metal on all our
cameras now, literally. The drawings of all the metal parts for Pancam and the Microscopic Imager
were completed last week, and they've now been sent to the machine shops for the building to begin.
These are the same machine shops that will be cutting metal for both rovers before long, so we
figured we'd better get our order in early! It shouldn't be long before we have the real flight
camera bodies in our hands.
Week Ending June 9, 2001
The star of the show lately has been Mini-TES. We
learned a lot when we built the first
one, and we're using what we learned now as we build Mini-TES 2. Not only are we weeks
ahead of schedule, it's starting to look like a real instrument. It'll be on its way to
Mars in just two more years.
The other Mini-TES news is that we've figured out how we're going to keep from pointing
it at the sun accidentally, which we were worried about last week. The best answer turns
out to be the simplest one. The rover always knows roughly which way it's pointed, and
also what time it is... which means that it can figure out where the sun is. So we keep
Mini-TES pointed away from where the rover thinks the sun is, and we keep it far enough
away that even if the rover's off by a little, Mini-TES will be safe anyway.
Week Ending June 2, 2001
We've got another problem on our hands this week. We did some calculations a while ago,
and they showed that if we were ever to point Mini-TES at the sun we could damage the
instrument. That's not bad news scientifically... there's no reason we'd want to look at
the sun with Mini-TES anyway. But what if we did it accidentally? We could have a toasted
spectrometer on our hands.
So now we have to figure out how to keep such an accident from ever happening. It shouldn't
be hard... it's easy to calculate where the sun will be in the sky, and we'll just make sure
that we don't point Mini-TES in a dangerous direction. But it's one more thing to put in the
software, and time is getting tight. As of this week, we're less than two years away from launch.
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Week Ending May 26, 2001
We've had a little bit of a problem lately. Our rovers are big
machines, and they each have to be folded up in a complicated way
to fit inside their lander. After landing, we need to fold out lots
of important pieces: the wheels, the antenna, the camera mast, and
so forth. Each of these pieces needs to be held firmly in place
before it folds out, so that vibrations during launch and
landing don't do any damage. The difficulty is figuring out
how to release each piece. The usual way you do this on a spacecraft
is with what's called a "pyro": a little explosive device. Pyros
are very simple and reliable. Problem is, this rover is folded up
so tight that we'd have to set these little explosions off right
next to our instruments, and some recent calculations have suggested
that the shock might be so great that instruments could be damaged.
So we're looking for a better way to do it.
Week Ending May 19, 2001
The Rock Abrasion Tool (a.k.a. The RAT)
passed an important milestone this week: its Critical Design Review.
We still have one or two odds and ends to work out, but with this
review behind us now it means that we're ready to start building
the real RATs that will go to Mars.
Week Ending May 12, 2001
We conducted an enormously successful test this past week with the
FIDO rover. This is a prototype of
the MER rovers, and we used it to simulate twenty days worth of
rover operations on the surface of Mars. The rover itself was in
the Mojave Desert, and we operated it "in the blind" from the
Jet Propulsion Laboratory, just as we will with the real rovers
at Mars. We investigated a number of rocks and soils, took lots
of images and spectra, and drove over 120 meters. Most importantly,
we learned a lot about how we'll operate the MER rovers
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Week Ending April 28, 2001
Rocket launches are pretty violent events, with lots of noise and lots of vibration. All of our hardware has to
survive launch, so we spent a lot of time thinking about how to make sure our designs are sturdy enough to take
it. The real proof, though, is testing. This past week our APXS instrument faced its first vibration test. Vibe
tests can be a little scary. You put the instrument on a "shake table" that vibrates it as violently as a launch
will (or even harder). Sometimes things break. The APXS passed with flying colors, though, so it looks like we've
got a solid design.
Week Ending April 21, 2001
We made a little change to the payload this week. The RAT is a very cool little machine, and we expect it to work
really well. There's just one problem. While we're confident that the RAT will be able to grind into hard martian
rocks just fine, we're worried about soft rocks. The grinding wheels on the RAT are a little like sandpaper, and
when we grind into really soft rock we've found that they can get "gummed up". It's simple, really -- tiny particles
of rock get caught between the little diamonds that do the grinding, and if too much of that happens the RAT just
can't work well any more. It's a low-tech problem, and we're using a low-tech solution: putting a stiff wire brush
on the rover that we can use to clean the RAT off after each use.
Who says rocket science is complicated?
Week Ending April 14, 2001
This week we finished up our second operations test with the FIDO rover. Just like two weeks ago, we spent Thursday
and Friday simulating four martian days of rover operations. These past two tests have taken place with the rover
in the "Mars Yard" at JPL... an outdoor facility that looks like a little bit of Mars. The test this week went
really well, and we feel now like maybe we're ready for something bigger. We'd better be. Just two weeks from now
we'll begin a 10-day test with the rover somewhere out in the desert.
Week Ending April 7, 2001
This was a landmark week for our project: the Mars Odyssey orbiter was launched! Odyssey is a great mission by
itself, and it's also very important to our rovers. The rovers can transmit some of their data directly to Earth,
but a lot of it -- including many of the best pictures -- will be relayed to Earth by an orbiter overhead. And Mars
Odyssey is that orbiter. The launch was picture-perfect. The weather was as good as it gets, and Boeing's Delta II
rocket gave Odyssey a flawless ride. So Odyssey's on its way to Mars now, and should be waiting there for us when
we arrive in 2004.
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