Week Ending March 31, 2001
The big event this past week was our first test of Mars Exploration Rover operations. We did it using the FIDO
rover, which is an early prototype of the rovers we'll be launching in 2003. The test was a pretty wild experience:
a couple of dozen scientists and engineers spending two solid days in a detailed simulation of everything we'll do
once the MER rovers are on Mars. We learned a lot! We'll have to do it a lot more, too. The way to train for space
flight has always been to do plenty of simulations ahead of time, and this project is no exception. Our next test
will be two weeks from now.
Week Ending March 17, 2001
We had a great week! On Wednesday, we pulled Mini-TES 1 out of storage and fired it up in what is called an
"aliveness test". This is just what it sounds like: a test to see if the instrument is still alive. We didn't
expect anything bad, but any time you pull five million bucks worth of hardware out of storage after nine months,
there's a little bit of anxiety the first time you hit that power switch. As it turns out, there was no cause for
worry -- Mini-TES 1 works just as well now as it did the last time we used it. It's a good thing, too, since it's
going to have to go in one of the rovers. Now all we have to do is build another Mini-TES to go in the other one...
Week Ending March 10, 2001
We had a very good week... one of those weeks where you make progress on a dozen different things at once. We've
now got a design for the door that will protect the APXS from dust. We've almost got the design worked out for the
"contact sensor" that will tell us when the Mössbauer Spectrometer has touched a target. The new Pancam electronics
are coming together. And we seem to have finally decided how we're going to keep the insides of the Mini-TES as dry
as they need to be in the humidity of Florida when it's time to launch. That's the good news. The bad news is that
we're going to have to keep making progress at close to this pace if we're going to make it to the launch pad in time.
Week Ending March 3, 2001
We made a really major change this week: We added a dust cover to the Microscopic Imager. That may not sound like
a big deal, but at this stage of the game, it is. The reason we did it, obviously, is that Mars is a very dusty
place, and we were worried that at some point we might accidentally push the microscopic imager into the dirt. The
reason it's a big deal is that it adds more complexity to an already complex system: another motor, more wires, the
mass of the cover, the software to make it all work, the testing to prove that it works, and so forth. But it was
the right thing to do, and now we feel comfortable that we'll be able to keep that lens as clean as we need it to be.
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Week Ending February 24, 2001
The guys at Honeybee Robotics have been making a lot of progress lately on the Rock Abrasion tool, also known as
the RAT. The RAT is the one really new invention on our payload for 2003, so we're devoting a lot of attention to
making sure we get it right. We held a Preliminary Design Review for it several weeks ago, the result of which was
a thumbs-up to go forward with the detailed design work. The mechanical design of the RAT is pretty far along now,
and much of the focus this past week has been on the electronics that go with it. This thing has a lot of wires,
and we're building a full-scale mockup of it to help us figure out exactly where to run them all. We're also testing
what are called "breadboard" electronics -- electronics that do the same things that the final version will, but
that are built so that they're easy to take apart and change while we're still figuring out how to get it all to work.
Week Ending February 17, 2001
With the recent round of reviews now behind us, we're starting to turn our attention to the business of practicing
rover operations. This spring we're planning to do three tests with JPL's FIDO rover. There will be a couple of
two-day tests in the JPL "Mars Yard" in late March and mid-April. The Mars Yard is an outdoor facility at JPL that
looks enough like Mars that it's a good place to take a rover for a spin. Then, at the beginning of May, we're going
to do a 10-day field test. We don't know where the field site is -- or at least most of us don't. It'll be a "blind"
test, where the location is unknown to the operations team. We do it this way so that we'll be almost as ignorant
about the landing site as we'll be with the real rovers once they land on Mars.
Watch this website for news on the upcoming tests, and lots of pictures once they start to happen!
Week Ending February 10, 2001
We've been starting to think hard lately about what's called "fault protection". This is basically the business of
making sure you don't break a very expensive piece of equipment once you get it to Mars! A good example of what we've
been working on is Mini-TES. It's a great instrument, but if you accidentally point it straight at the Sun you could
be in big trouble. Mini-TES isn't built to handle that much heat and light, and if we stare right at the Sun for too
long with it we could damage it, maybe permanently. So we have to make the rover smart enough not to accidentally
point Mini-TES at the Sun. We know how to do this: The rover has a special camera for figuring out where the Sun is,
and the onboard computer uses this information to keep Mini-TES safe. But it's one more thing to worry about on a
very complicated machine.
Week Ending February 3, 2001
With the landing site work done for now, the focus is back on hardware issues this week. One of the things we're
dealing with now is what's called "contact sensing". Two of our instruments, Pancam and Mini-TES, will look at Mars
from atop a mast on each rover. They don't need to actually touch the rocks and soils that they're looking at. The
other four pieces of the payload, though, need to touch the surface, which is why they're all on the end of an arm.
But how do you tell when they're actually in contact with the surface? Taking pictures would do it, of course, but
that would mean taking the time to transmit the pictures to Earth and look at them, which we don't want to do.
Instead, we're equipping each instrument with contact sensors -- little switches that close when the instrument
gets pressed against a rock, telling the rover that the instrument is where it needs to be.
Of course, it's not quite that simple. Each instrument is different, so the kinds of contact sensors tend to be
different too. And we don't know how strong some of our targets will be... you might press an instrument against
a target, only to find that it's very soft, fluffy soil, so that the switch doesn't close. But we seem to be making
good progress. As of this week, we've got all of the contact sensors figured out except for the one for the
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Week Ending January 27, 2001
The big event of this past week was the Mars landing site workshop at NASA's Ames Research Center. Nearly a hundred
people came to this workshop to help select landing sites for our two rovers. At the beginning of the workshop there
were 185 candidate sites. By the end, nine highest-priority sites had been chosen, along with a number of others.
Among the nine are some fantastic places: sites with weird minerals on the surface, sites with old sediments that
may have been laid down in ancient lakes, sites inside the biggest canyon in the solar system. The next step is
going to be for the Mars Global Surveyor spacecraft to spend several months taking high-resolution pictures of all
the top sites. Then we'll see what we see.
Week Ending January 20, 2001
A big issue for us this week has been dust... or more specifically, how to protect the APXS instrument from dust.
The APXS has some pretty sensitive parts in it, particularly the detectors that we'll use to figure out what martian
rocks are made of. If those detectors get too dirty then they won't work... and Mars is a pretty dirty place. Our
plan has been to have some protective doors over the instrument that will open when we want to use it, and close to
protect it from dust when we don't. But how to open and close the doors? We thought about a motor, but motors tend
to be heavy and also would require more wires running up the instrument arm. So instead, it looks like we're going
to design a little gizmo that's sort of like the clicker on a ballpoint pen. Use the arm to press the instrument
once against a hard surface and click, the door will pop open. Make the measurement and then press it again and
click, the door pops closed again. The hard surface can be someplace on the rover, or it can be a martian rock.
This way we'll get the dust protection we need, but we'll avoid new wires and motors.
Week Ending January 13, 2001
It was a very busy week, with two big events. The first was the Preliminary Design Review for the RAT. The review
turned up the usual number of little technical issues, but no major problems. Our next step will be to build the
"brassboard" RAT, which is a preliminary version that will look and work very much like the flight units.
The second big event of the week was a workshop where we invited in a number of the world's leading sleep
researchers to meet with some of the team. The martian day is about 24.6 hours long -- a little bit longer than
the Earth's 24 hours. During operations, the whole flight team is going to have to live on Mars time, not Earth
time, and if we're not careful it's going to wreak havoc with people's schedules. The sleep researchers gave us
lots of good advice on how to adapt to that kind of crazy work schedule for months on end. From the sound if it,
it's going to be an interesting experience!
Week Ending January 6, 2001
Things are back in full swing after the holidays. There's been a lot happening this past week. Perhaps the most
significant thing is that we've now got a good idea how much radiation the radioactive material in the Mössbauer
Spectrometer will produce, and how much damage the radiation might do to some of the cameras on the rover,
including the Microscopic Imager. The answer, unfortunately isn't simple. The amount is not so tiny that we can
ignore it, nor is it so great that we clearly have to fix it. It's in that uncomfortable in-between zone, where
we still don't know for sure if we need to do something in the design to account for it. So there's still more
work to be done.
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