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News Update Archive

December 2000

Week Ending December 30, 2000

It's been a quiet week for a change! Work doesn't stop completely over the holidays, but things have slowed down a good deal. It's the calm before the storm. January is wall-to-wall with design reviews. Highlights over the next few weeks include preliminary design reviews (we call 'em PDRs) for the RAT and the instrument arm, along with what's called the "delta" PDR for the whole MER project... a review where we'll clean up the issues that were left open after the big project PDR we had back in October. Another thing coming up soon is our first landing site workshop, where several dozen Mars scientists will get together to start to narrow down the many possibilities for where we'll land. So we're kicking off this century about like we ended the last one... in high gear.

Week Ending December 16, 2000

The big deal this week has been radiation. One of our instruments, the Mössbauer Spectrometer, has a little bit of radioactive cobalt-57 in it. The radiation output is small, but it turns out that it may be enough that we need to worry about what it could do to some of our other instruments. The Microscopic Imager sits very close to the Mössbauer, and it hassome electronic components in it that don't like radiation much. We've now measured how much radiation the Mössbauer produces, and the next step is going to be to figure out exactly where the Mössbauer will sit with respect to the Microscopic Imager. If it ends up so close that the MI doesn't like it, we'll wrap a little shielding around the Mössbauer to keep the MI safe from the radiation.

Week Ending December 9, 2000

The big issue this week has been what's called the "purge" for the Mini-TES instrument. Mini-TES is a great piece of hardware, but it's got some touchy components. One of the ones we have to worry about most is deep inside the instrument... a piece of optics called a beamsplitter. What it does is pretty simple, but it's made out of a very special material called potassium bromide. Potassium bromide is great stuff, but it has one very nasty characteristic: If it ever gets exposed to too much humidity, it turns cloudy and is ruined forever. That's not a big deal in the laboratory or on Mars, but it's a major problem at launch... the launch site in Florida is in the middle of a swamp! So we're wrestling with the best way to make sure it'll stay nice and dry while we're waiting to light the rocket off. Sending a steady "purge" of dry nitrogen gas through the instrument is the way to go. But do we take the easy way out and turn the purge off hours before launch? Or do we do it the hard way and try to keep the purge going right up to T-minus-zero? We're still working on this one...

Week Ending December 2, 2000

We're making real progress with the RAT -- our Rock Abrasion Tool. Honeybee Robotics (where the RAT is being built) is in Manhattan, and a few weeks ago a bunch of the guys from Honeybee piled into a pickup truck, drove to New Jersey, and dug up a few hundred pounds of Palisades basalt. This is very tough rock... as tough as anything we expect to find on Mars. We've now got an early version of the RAT working, and it can grind very nicely into this stuff-- (click here for an image). The next version of the RAT will be even nicer, and will get rid of that little "island" of rock that you can see in the picture.
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November 2000

Week Ending November 25, 2000

The big issue this week has been how we're going to provide power to our two German instruments -- the APXS and the Mössbauer Spectrometer. The rover solar arrays provide power at about 28 volts, but these instruments need other voltages: 6 volts for the Mössbauer, 5 and 12 volts for the APXS. So we have to convert from what the rover provides to what we need. Converting voltages isn't particularly hard for most kinds of electronics, but we have to use something that will work reliably in the radiation environment of space, and that will use power as efficiently as possible... we don't have much power to spare! After working on this for weeks, it looks like we're finally on the track of something that will work.

Week Ending November 18, 2000

The big issue this week has been how we're going to provide power to our two German instruments -- the APXS and the Mössbauer Spectrometer. The rover solar arrays provide power at about 28 volts, but these instruments need other voltages: 6 volts for the Mössbauer, 5 and 12 volts for the APXS. So we have to convert from what the rover provides to what we need. Converting voltages isn't particularly hard for most kinds of electronics, but we have to use something that will work reliably in the radiation environment of space, and that will use power as efficiently as possible... we don't have much power to spare! After working on this for weeks, it looks like we're finally on the track of something that will work.

Week Ending November 11, 2000

We've made an important change to the RAT... our Rock Abrasion Tool. The RAT uses a set of grinding wheels to work its way into martian rocks, exposing subsurface materials for the instruments to look at. The old design had a spike down the center to hold the RAT in place while the grinding wheels did their work. This was fine, but it left a small "island" of unabraded rock still standing after the RAT was done. Tom Myrick at Honeybee Robotics finally came up with a solution to this problem this week: a ring around the outside of the RAT instead, with a built-in pivot that allows it to adjust to the shape of the rock. With this change, the island is gone, and the instruments should see a smooth, flat surface of fresh rock each time the RAT has finished its work.

Week Ending November 4, 2000

We've been dealing with lots of odds and ends this week -- nothing momentous, just the day-to-day stuff that in the end will determine whether or not this mission will really work. What kind of power converters to use in the Mössbauer spectrometer? How to make sure that the interior of the Mini-TES stays nice and dry in the humid Florida summer when it's time to launch? How far apart should the Pancam cameras be spaced? What kind of material to use in the RAT grinding wheels? With the Preliminary Design Review behind us now, it's now time to get all these issues settled. And it's going to be time to start building hardware again before too long...
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October 2000

Week Ending October 21, 2000

Well, we survived our Preliminary Design Review. This was a very big deal... there were nearly 250 people there! (Someone was joking that we may have to rent out the Rose Bowl when it's time for the Critical Design Review.) Anyway, it went pretty well. We've got a long way to go, and it's going to be a challenge to get this whole thing to work... especially to land a spacecraft this heavy using the Pathfinder airbag system. But it looks like we'll make it, and there was no question that the science payload is in pretty good shape for this stage of the game.

Work has been going on even while the review was happening. The biggest development of the past week is that we have changed the design of the Microscopic Imager optics slightly. This is stuff that's familiar to any photographer: We've decided to "stop down" our lens to get more depth of field. We'll need to take somewhat longer exposures to make it work, but the net result is that this camera should be a lot easier to focus than it would have been with the previous design.

Week Ending October 14, 2000

It's PDR Week... time for the Preliminary Design Review. Everybody on the project has been spending weeks in preparation for this. NASA has put together what sounds like a very high-powered review board to check us out, and we're going to be spending three days showing them what we've got. Just about everything gets reviewed... hardware designs, schedules, budgets, the works. There won't be any time to rest once it's over, but no matter how it comes out it's going to be good to get this one under our belts.

Week Ending October 7, 2000

Things are happening so fast, and on so many fronts, that it's almost impossible to keep track. Here are just two examples of the dozens of things we've been thinking about this past week. One is where to put the calibration target for Mini-TES. This target is what we look at with Mini-TES to figure out how well the instrument is working. After some thought, we've decided to put it on the back side of the rover's main radio antenna... the one we'll use to talk to Earth. The nice thing about this is that putting target there doesn't take up space on the rover's solar array, which is our only source of electrical power. But the bad thing is that it means that we can't look at the target and talk to Earth at the same time.

A second issue is how to protect the APXS from martian dust. We have a dust cover designed... it's a set of doors on the front of the instrument that can open and close. But how to open and close the doors? A separate motor would be complicated, so we want to just use the arm to press the doors against some surface, moving the doors. The new concept, courtesy of Steve Kondos at JPL, is a mechanism like the one in a ball-point pen... one click to open the doors, and another to close them. Clever idea... now all we have to do is design it!
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