Martian Chronicles VIII: Torture Tests
Three spacecrafts are now hurtling toward the Red Planet to look for evidence that it might once have been wet enough to sustain life. Orbital projections of where Europe’s Mars Express and the two NASA Mars Exploration Rovers (MER) are right now, can be continuously monitored over their half-year journeys. Experiments performed by the MERs will help to determine whether water might have once existed in volume on the red planet. The two Mars Exploration Rovers are targeting what imagery indicates might have been ancient dry lake beds and other geologically interesting sites in early 2004.
|A simulated image of the new Mars rover carrying the Athena science instruments.|
The Martian Chronicles series gives an inside view of what it takes for scientists to deliver a complex mars mission. The journal entries are from Cornell’s Steve Squyres, the Principal Investigator for the Mars Exploration Rovers’ scientific package called Athena. The chronicles begin sequentially from the beginning of July 1999, four years before launch, and will culminate in the dramatic landing of the twin rovers on Mars in January 2004. The expected mission time roaming the red planet is ninety days, from January to April.
The chronicles include an insider’s view of hardware tests and site selection to problem solving and science planning on the surface of Mars.
June 8, 2002
We had a breakthrough in the development of our RAT this week. RAT stands for Rock Abrasion Tool, and it’s what we’ll use to grind the dusty and weathered surfaces off of martian rocks, exposing fresh rock underneath. It works well, and the RAT can grind about half a centimeter into even very hard rock. The problem, though, is that sometimes the dust created by all that grinding winds up filling the hole. And that’s not exactly where we want dust to be, since the whole point of the RAT is to expose the clean rock underneath.
So what to do? We’re running out of time, and big design changes are out of the question at this point. The guys at Honeybee Robotics went to work on it, and came up with a simple solution that sounded like it ought to work: A new brush built into the RAT. The RAT already has a part that revolves slowly as the grinding takes place, and if we mounted a brush to this part and then spun it for awhile after the grinding was done, we figured that maybe that would do the trick. Turns out that it does. On Thursday we ran a test that was a duplicate of one we had done several weeks ago that had filled the hole with dust. The new brush cleared things right out, producing a nice clean rock surface. And it’s a good thing it worked, too, since we’ve got to start bolting RATs onto rovers in not too many more weeks. It doesn’t matter how clever you are if you run out of time before you run out of ideas.
June 15, 2002
We have finally finished torturing Mini-TES.
Before you can put anything on top of a rocket, you have to test it to make sure it can withstand all the rigors of spaceflight. It’s necessary, but that doesn’t mean it’s fun. Over the past couple of weeks, we’ve finally finished doing all the testing we need to do on Mini-TES. It’s scary stuff. The week before last, we did a test where we simulate what happens when you fire a "pyrotechnic" device on the rover. These are little explosive devices that are used to do things like release the instrument arm or the camera mast right after we land. They’re very small explosions, but they’re explosions nonetheless, and we have to make sure that when we fire them off we won’t hurt Mini-TES. We simulated it, and nothing broke.
|A simulated image of the Mars rover carrying the Athena science instruments against the horizon of the Mars rust-colored sky.|
Just as scary was the test that simulates landing. Even though our lander is cushioned by airbags, it still hits the martian surface pretty hard. So, of course, we have to make sure Mini-TES can survive that too. We don’t do this by putting it in a lander and dropping it… we do it by putting it into a giant centrifuge, and spinning it until it feels stresses even worse than what it’ll feel on landing. We survived that too, thank goodness, and the torture testing of Mini-TES is now over.
Except, of course, next year when we put ‘em both on real rockets and send them off to Mars…
June 22, 2002
What a week… the APXS is done and Pancam is taking pictures!
After a huge amount of work over in Germany, Rudi and Ralf came over with two completed APXS instruments this week. The electronics boards for each one are the ones that are actually going to Mars, and the team at JPL should start working with them sometime this week. The sensor heads — the part that goes out on the arm — that they brought over are spare units. We can fly these spares if we have to, but we’re planning on flying sensor heads that are still back in Germany and about to begin months of testing. If all that testing goes well, we’ll swap the spare sensor head with the flight units sometime in the fall.
And the Pancam pictures are beautiful! We just got the first Pancam put together early last week, and it took a perfect picture the first time we pushed the button. Amazing. This one is an engineering model, so it’s not going to Mars either. But the flight cameras are identical to it, and those will be coming together over the next few weeks. As soon as we have some good pictures from those, we’ll put ‘em on this web site for the world to see.
June 29, 2002
We’ve just gotten the first pictures taken by our Microscopic Imager, and they’re fantastic! The picture that you see shows the surface of a rock, and covers an area about 3 centimeters (a little over an inch) across. You can see features in the images down to considerably less than 100 micrometers in size… less than the width of a human hair. It’s really exciting to start seeing data like this, and we can’t help but think what it’s going to feel like the first time we see Mars at this scale
July 6, 2002
We had another big week camera-wise! Last week it was the Engineering Model of the Miscroscopic Imager. This week, it was the first flight Pancams. It takes awhile to get these things ready, that’s for sure. But Dave Thiessen and the rest of the camera crew at JPL put in some very long hours last week, and we now have the first real flight Pancams — ones that are going to Mars — in our hands. They’re beautiful! It’ll be a little while before they’re taking pictures of anything interesting, but as soon as we have something to show we’ll post them here on this site.
And there have been big rover developments lately too. For a look at some recent progress, here’s a picture of the Dynamic Test Model rover. This one isn’t going to Mars — it’s a test model that we’ll use to make sure that the ones that really are going can withstand all the rigors of flight. But it looks very much like what part of each flight rover will look like when it’s folded up and stowed inside it’s lander.
July 20, 2002
As we get closer and closer to flight, our attention is gradually shifting away from the individual instruments, and more toward the business of putting the rovers together. We’re almost "done" now with many of the instruments on an individual basis. The flight Mini-TES and Moessbauer instruments really are done. The flight APXS instruments are half-done, and the parts that aren’t done yet are coming together quickly in Germany. The RATs should be done in a few weeks, and we now have the first flight Pancams and Microscopic Imagers in our hands and taking pictures. There’s still plenty more work ahead, of course, but we really are getting to the point where getting ready to put things into the rovers is the main focus.
And so we’re very interested in how the rovers are doing! Fortunately, they seem to be doing pretty well. This past week, the Dynamic Test Model rover did its very first "mobility test". In other words, our baby took its first steps! It didn’t go far, and the test wasn’t without a glitch or two. But we have a real test rover now that can move, and that’s a huge accomplishment.
July 27, 2002
Shake a science camera and you might kick up some dust. That’s what happened to the Microscopic Imager after a vibration test this week. When a delicate science instrument undergoes such a test, more tests are conducted "post-vibe" to make sure it is still functioning properly. One of these functional tests showed that small dust particles somewhere in the optics of the MI had moved slightly during vibration. This was not unexpected and we were able to confirm that we still have a healthy MI producing excellent images. But we want to take care of the dust problem and the good news is that it can be easily corrected.
August 3, 2002
We just completed a test that lasted for an entire month. That may be your definition of a nightmare, but it’s our way of learning how to avoid trouble when we’re on the surface Mars. They are called "thread tests," and there will be several of them over the next few months. During the most recent exercise, we practiced the "uplink" procedure. That’s when we send information from Earth to Mars to command the rovers. We used images of the Martian landscape taken from the Pathfinder mission to formulate our uplink plan. If this were the real thing, we’d be working with images sent to us from the rovers. We studied surface features, selected rock targets, and created a list of commands. We practiced using all the procedures, processes and software that we will use for an uplink during the actual mission. As with any test, there were glitches along the way. But they helped us identify what needs to be corrected before we land on Mars.
August 10, 2002
It’s been almost impossible to even write a news update this week, since we’ve been so busy. We’re in the middle of a test with the FIDO rover. FIDO is a rover similar to the ones that we’ll be sending to Mars, and it’s one that we can send out into real field settings to do real geology. Right now it’s somewhere in the American Southwest (I don’t know where), and we’re driving it every day as if it were on Mars. The reason I don’t know where it is is that this is a "blind" test. When we run the real rovers on Mars we’re not going to know very much at all about where they really are, so making the test blind like this — not telling the science team where the rover is — is the only realistic way to do the test.
We’re three days into a 10-day test as I write this, and it’s going wonderfully so far. The geology at the "landing site" is fantastic, the rover is working well, and the team is working well together. Watch this website for updates… as soon as we have some images from the test that we can post, we’ll put ‘em here.
August 24, 2002
Well, if the last couple of weeks weren’t enough to teach us how to do science with a rover on Mars, there isn’t much hope for us. We’ve just finished a ten-day test using the FIDO rover to simulate twenty martian days of MER operations. The FIDO guys took their baby out to a site somewhere out in the American Southwest, and we drove it from JPL just like we’ll drive the real MER rovers when they’re on Mars. The "landing site" was fantastic, with no vegetation, great rocks, and many geologic puzzles for us to solve. Very Mars-like!
In our twenty "sols" of operations, we drove the rover more than 200 meters, made a bunch of detailed measurements of the chemistry of the rocks, and took a lot of spectacular pictures. Most importantly, the whole team learned an enormous amount about how to do this kind of thing on Mars. We have some great field geologists on our team, but they’re used to doing geology in their own boots, with their own eyes and hands. FIDO has helped them to re-learn their trade, teaching them how to do field geology through the eyes of a robot.
We made some mistakes, of course, which in a way was the best news of all. We’re going to have to do this for real in about a year and a half, so it’s good to make mistakes we can learn from now!
August 31, 2002
It’s alive! Our first rover arm has been delivered, and it’s working beautifully.
Each MER rover will carry a robotic arm that we’ll use to position four of our scientific instruments: the Microscopic Imager, the APXS, the Moessbauer Spectrometer, and the RAT. The arm is the same size as a human arm, and like a human arm has a shoulder, an elbow, and a wrist.
Our first flight arm — one of the ones that’s going to Mars — recently arrived at JPL, and we’ve been putting it through its paces. We haven’t put any of the instruments on it yet, though that’ll happen soon. What we’ve done this past week has been to mount the arm on a rack, hook it up to the rover’s electronics, and start seeing how well it moves. The real question on our minds has been how well the arm will be able to position the instruments, and the preliminary answer seems to be very well indeed. We still have to actually mount it on the rover body and run it at real martian temperatures, but all the indications so far are that it will be able to put the instruments where we want them every bit as accurately as we had hoped, or maybe even better.
And on top of that, it’s really something to see as the arm moves all its joints and reaches out toward some imaginary martian rock. It’ll be doing the real thing soon enough.
September 7, 2002
This has been another one of those weeks where there’s so much happening that it’s hard to decide what to write about. It’s likely to be like that from here to the launch pads.
We officially finished our first Microscopic Imager this week. It’s built, tested, and delivered. Only five more science cameras to go!
This newly-delivered Microscopic Imager now joins our two Moessbauer Spectrometers, our two APX Spectrometers, our two Mini-TESes, and the first of our two Rock Abrasion Tools as pieces of hardware that are ready to go to Mars. The second RAT should be ready to go in another week or two, and the other five cameras aren’t far behind.
It won’t be long before some of the instruments are in place, either. The first of our two instrument arms has now completed its testing and is ready to take on some instruments. Within another week or so, we may have a whole bunch of them mounted onto an arm for the first time.
And there’s so much more going on, too. The first Mini-TES is mounted to its rover deck. The first Pancam Mast Assembly (the big mast that supports both Mini-TES and Pancam is done and is about to be mounted to the same deck. And the first assembled rover has been mounted to its lander and is ready for testing. We’re cookin’!
September 14, 2002
One of the things about our mission is that we’re "hardware rich"; we have a lot of stuff going to Mars. It’s a blessing, but it can also be a curse.
This week, we mounted our first two completed Pancams to the camera bar that goes at the top of the rover’s mast. These are two out of the total of four Pancams that we have built, and out of the eighteen cameras in all that will go on both rovers. That’s a lot of cameras.
Here’s a nice picture of the two Pancams, along with two Navigation Cameras, as they were mounted on the camera bar. We spent about eight hours getting these suckers properly mounted, precisely aligned, and ready to go. Took a good look at our handiwork, congratulated ourselves on a job well done… and then noticed we had ‘em reversed: right camera on the left, and left camera on the right. Ouch.
The Pancams look almost identical from the outside, but they’re not. Each has a wheel containing eight color filters, and the filter sets are very different in the two cameras.
So why not just leave them where they were? Well, for one thing, we’ve got an awful lot of software already written that expects one set of filters to be on the left and the other to be on the right. And it would have taken a lot more time to rewrite and re-test all that software than whatever it was going to take to switch the cameras. So off they came. We’ve got it right now, and you can bet we’re going to get it right the first time when we do the next camera bar!
September 21, 2002
We had a million things happen this week, but it all pales in comparison to the news from the parachute test.
Landing on Mars is hard, and one of the toughest parts of this job has been figuring out how to get our rovers down safely. The airbags that we use to cushion our impact on the surface gave us fits for quite a while, and it was only several months ago that we finally found an airbag design that we’re confident will work.
The parachute problem has been even worse. We did a set of chute tests back in May and June, and they did not go well. The chutes would deploy just fine, but as soon as they completely filled with air the pressure on them was too much. It gives you a pretty sick feeling to watch the parachute that you hoped was going to land you safely on Mars rip to shreds!
Over the past several months, Adam Steltzner, Wayne Lee, and the rest of our EDL team have been working on the chute problem. The moment of truth for the newest chute design came this past Thursday, at NASA’s Ames Research Center. Ames has an enormous wind tunnel. It’s big enough to put a small airliner in, and it’s easily big enough to do a full-scale deployment of our parachute. They cranked the fans up, popped the chute… and it worked! There was no damage at all. Just a big, solid, beautiful bowl of a parachute.
We don’t have to start building our flight chutes until November, so we’re going to spend another several weeks doing more testing, to make sure that whatever we fly is as good ast it can be. But this problem, which frankly had some of us pretty worried, now finally seems to be under control. This week we took a crucial step forward on the road to Mars.
September 21, 2002
It’s said that one picture is worth a thousand words. Here’s one that’s worth that and more. Click here to see a picture that we recently took with the Pancam camera on the MER-2 rover. It’s a pretty simple picture, just looking across the room at the cruise stage for the MER-1 spacecraft. But it’s the first image that we’ve taken that really gives a sense of how good our pictures of Mars will be. This is just a single Pancam image, but consider this: A full Pancam panorama of Mars will be four of these images high, and twenty-four of these images around! We’re not going to see anything that looks like this cruise stage when we get there, but we’re going to get quite a spectacular view of the surface of Mars.
October 5, 2002
You have good times and bad times on any project; the past few weeks may have been the best times we’ve had since we started this thing years ago.
Right now the momentum and the morale on the MER project are the highest they’ve ever been. The two biggest technical challenges that we once faced — finding airbag and parachute designs that will work — are now finally behind us. All of the instruments have been built and delivered. And, best of all, we’re starting to see fully assembled hardware.
Here is a picture of the MER-1 spacecraft all put together and ready for testing. You can see the heatshield at the bottom, the backshell that protects the lander above that, and then the cruise stage at the top. There’s a lander inside this thing, and inside that there’s a rover! The whole vehicle is almost ready to go "up the hill", as we say… to be moved to the facilities where it will go through tests to simulate the vibration, noise, temperatures, and other effects of launch and flight to Mars.