Week Ending December 29, 2001
No mission update for the week ending December 29, 2001.
Week Ending December 22, 2001
We've made good progress with the latest round of Mini-TES
testing. After all the problems
we had with Mini-TES 2 not working right when it was tilted,
we decided a few weeks ago that we had better pull Mini-TES 1 out
of storage and make sure that it was okay. We shipped it up to
Santa Barbara (carefully!), and the guys there have spent the last
couple of weeks checking it out. It's fine, as it turns out...
everything works as it should. So now we know that both instruments
for both rovers will behave themselves properly no matter how we tilt
them. We don't want to fly instruments that won't work right if the
rover is parked on a hill!
Everybody on the project is going to take a well-deserved rest
for the coming week, so the next weekly update will be after the
first of the new year. Happy holidays to one and all.
Week Ending December 15, 2001
A long-standing problem with the rover's arm was solved this week.
The arm's job is to place several of our instruments onto martian
rocks. Time on Mars is a precious commodity, so to keep from wasting
time we'll often use the arm at night. But it gets really
cold at night on Mars. So the motors on the arm need to have heaters
on them, allowing the arm to move properly even when it's really
The problem is this: What happens if we make a mistake and leave
the heaters on in the daytime? The answer, unfortunately, is that
the motors could get overheated -- cooked, really -- and be permanently
damaged. Not good. For awhile there, it looked like maybe we were
going to have to use much weaker heaters, which would have been safe
but which would not have worked well at night. Instead, someone at
JPL came up with a very slick design in which the motors are
automatically protected from overheating by a thermostat. If a
heater goes on at night then everything is fine, but if we leave it
on accidentally in the daytime, the thermostat will automatically
shut it off. So we can use the arm at night after all.
Oh yes, and I almost forgot... the Mission System Critical Design
Review was a big success!
Week Ending December 8, 2001
It's time for yet another big Critical Design Review. This one is
the Mission System CDR, scheduled for Tuesday through Thursday of this
coming week. A project like MER is divided into two big parts, called
the Flight System and the Mission System. The Flight System is the
hardware... the stuff that actually goes to Mars. The Mission System
is the stuff on the ground, back here on Earth. It's just as important
as the Flight System, because it's everything that makes the Flight
System work. Computers. Software. People... lots of 'em. People to
train the people. And so forth. For the past week (and for many weeks
before that), a huge amount of our time and effort has been spent getting
ready for a big review of the design of the MER Mission System. And
now it's time to do it. Let's hope it goes as well as our other CDRs
Week Ending December 1, 2001
The Mini-TES saga continues. We
found out some time back that the instrument wasn't quite working
right when we tilted it in certain directions. That's a big deal,
because the rover won't always park on level ground! It has been
a long road to track this one down, but we seem to be almost there.
Part of it was a problem with some wiring, but that wasn't all there
was to it. There was also a subtle problem in the electronics. We've
been testing the living daylights out of the instrument in Santa
Barbara lately, and with some minor tweaks to the electronics design
it now seems to be behaving itself nicely at every crazy angle the
rover could find itself at.
The instrument we've been doing this to has been our second
Mini-TES... the one that's still not finished. So now, just to be
safe, we have to test the one that we built a couple of years
ago and make sure that it works properly at all angles too.
This coming week, we're going to ship it (very carefully!) from
JPL up to Santa Barbara, and make real sure that it's behaving
itself as well.
Week Ending November 24, 2001
There's been bad news about our cameras lately, but there's been some
really good news too. Two weeks ago we were dealing with problems with
the electronics for Pancam and the
Microscopic Imager, and we're still dealing
with them. But this past week we got the first really good look
at the CCD's that we'll use for our cameras, and they're incredibly
good. CCD stands for "charge coupled device", and it's the detector
that lies at the heart of a digital camera -- the device that forms
the image, just as film does in a film camera. When CCD's are built,
it's typical for them to vary in quality. So normally you build a
bunch of them, and then put a lot of work into picking the few best ones
to fly. It didn't quite work that way with the CCD's for our cameras.
We built a whole bunch of them, alright, but now that we've checked
them out, we've found to our surprise they're nearly all about as close
to perfect as a CCD can be. The camera guys on our team are scratching
their heads now over which ones to fly, because they can hardly even
tell them apart. There are bad problems and good problems to have, and
this one's a good problem!
Week Ending November 17, 2001
We've had a hang-up with our cameras lately. The lenses are fine,
the detectors are fine, and all the mechanical pieces are fine.
But we're having some difficulties with the electronics. Both
of our cameras, Pancam and the
Microscopic Imager, use the same
electronics design. We got all our electronics boards built a
couple of weeks ago, but when we looked at them carefully we
realized that there was a problem. It's simple stuff, really:
the points where we have to attach little parts called
resistors to the boards are spaced too close together, and the
resistors won't fit. So now we have to have another set of
boards built, which is going to delay our camera schedule a
couple of weeks. This isn't a particularly big deal; stuff like
this happens all the time. But it's the kind of thing you spend
a lot of time worrying about when you get to this stage
in a space project.
Week Ending November 10, 2001
We learned something very interesting about the
RAT in the past couple of weeks. The RAT is our Rock
Abrasion Tool, and we'll use it on Mars to grind into rocks so that
we can see what's inside them. In all the RAT tests that we had
done until now, the grinding produced a lot of dust. Not only
that, but the dust formed a kind of "plume"... rising almost like
smoke as we'd grind away at the rock. This isn't good, since the
dust in the plume could contaminate some of our instruments. To
prevent contamination, we've put a "skirt" around the RAT, to
catch the dust.
Just recently, we did our first tests of the RAT in a special
chamber that creates Mars-like environmental conditions. The very good
news is that we saw no dust plume at all! Mars has a much less dense
atmosphere than Earth does, and apparently the dust particles that
the RAT creates are large enough that the martian atmosphere can't
suspend them. We'll still need a dust skirt, since the RAT could
always stir up martian dust, which we know is very fine. But now we
know that the dust created by the RAT itself is unlikely to create
much of a problem for us.
Week Ending November 3, 2001
Landing sites were a big focus again this week. We settled on our
landing sites in general terms at a meeting a couple of weeks ago.
We're down to four prime sites and two backups now, and they're all
really good. But it's not enough to pick the general areas where we
think we might want to land. Mars Global Surveyor is up there
taking pictures of these sites for us, and we need to tell them
exactly where to take those pictures so they know where
to point their camera. So this week we dialed in the exact positions
of the sites, and passed them along to the Mars Global Surveyor
folks. Now we have to be patient for a few months while MGS gets
those shots for us. Fortunately we've got until next spring before
we have to "downselect" to the final two sites.
Week Ending October 27, 2001
Mars Odyssey is in orbit!
The orbit insertion maneuver took place early this week,
and it went flawlessly. This is a huge step forward for NASA's
Mars exploration program, and our congratulations go out to
the Odyssey team. Odyssey will map Mars for several years, providing
new information about what the planet's surface materials are made
Odyssey is more than a scientific spacecraft. It's also a communication
satellite, and that's what makes it big news for us. Once our rovers
are on the martian surface, Odyssey will fly over each one twice
per day, collecting data from them by radio and relaying it to Earth.
We'll get roughly half of our data through Odyssey, so it feels very
good to have it safely in it's natural environment -- in orbit
Week Ending October 20, 2001
This was a huge week for us. We began this project over a year
ago with something like 185 possible landing sites for our rovers.
Now we're down to the Final Four. There was a big landing
site selection meeting this week, and dozens of scientists
who have spent their careers studying Mars were there. The
four sites that came out on top are the Meridiani "Hematite"
site, Melas Chasma in the Valles Marineris, Gusev Crater, and
a place called Athabasca Vallis in the Elysium region. They're
all great sites! Check out our landing site page
for more on all of them except Athabasca. (Athabasca was a bit of
a dark horse, and we don't have a map of it ready yet.
We'll provide an update with details soon.)
We have a big week ahead of us, too. On Tuesday evening, the
spacecraft is scheduled to go into orbit around Mars. This
is a terrific new science mission, and it also will be a
key communication satellite for our rovers once we get there
Week Ending October 13, 2001
The guys at Raytheon found and fixed our Mini-TES
problem this week. It was what we expected: a
cable had been put in the wrong place, and it caused a sensitive
part of the instrument to bend very slightly when we turned it
rightside-up. It wasn't much of a bend, but it was enough to cause
the trouble we were seeing. We opened the instrument up, re-routed
the cable, fastened everything back together, and then ran it through
its paces sideways, upside-down, and rightside-up. And now it works
right no matter which way we're tilted.
So now it's on to the next problem... whatever that turns out to
Week Ending October 6, 2001
Probably the most exciting thing going on this past week has been the
progress on our cameras: Pancam and
the Microscopic Imager. These were
problem areas for awhile, but they really seem to be coming around.
On a payload this big there's bound to be something that lags behind
everything else, and for us it has been the cameras. But the camera
work has really been going well lately. All of the mechanical
parts -- things like camera housings -- are now done. All of the
electronics boards should be done in another week and a half. And
the lenses are basically done too. So it's not going to be too long
now before we can start putting some real Mars cameras together...
and taking real pictures with them.