We had a real good week, for a change. The first piece of good news is that the Mössbauer problem that popped up during vibration testing a couple of weeks ago is easy to fix. Bodo and Goestar have already fixed the one broken instrument in Germany, and the next time they come over they're going to apply the same fix to the two good instruments already at JPL, just to be on the safe side.

The second piece of good news is that our second Mini-TES is now officially delivered to JPL. If you're keeping score, that's three and a half of our twelve payload elements delivered (two Mini-TESes and one and a half Moessbauers -- we've delivered two Moessbauer sensor heads, but only one of the electronics boards). Lots more to go!

Our landing site situation just changed again. Sometime in the next couple of months we were due to recommend our two final landing site choices to NASA. But now we've had a delay, and for once a delay in our schedule is a good thing.

The longer we can wait to pick our landing sites, the more we'll know about Mars. The Mars Odyssey spacecraft is just beginning to collect data at Mars, and it has started to return some fantastic new data for some of our possible sites. There has been very little time to study the data, and there's much more data to be taken. So if we can give Odyssey some more time, we'll know a lot more about Mars when the time comes to choose.

And it turns out that we have some more time. For months we have been very worried that the mass of our spacecraft might be too high. But lately, as we have gotten more and more hardware built and weighed, that has become less of a worry. So with a little breathing room now, we've realized we can add a little bit more rocket fuel to the design. And with that extra fuel aboard, we can now target each spacecraft to land just about anywhere we want on the planet. The bottom line is that instead of having to pick our sites soon and stick with them, we've got almost another whole year before we have to make up our minds.

This was Mössbauer week at JPL, and it was pretty wild. Goestar and Bodo brought over the sensor heads for both instruments. (The sensor head is the part that goes out on the rover's arm.) The big job for the week was to put them through vibration tests that simulate a rocket launch, and other tests that simulate the jolt of an airbag landing on Mars.

These tests are quite something to watch. It's a lot like what they say about being a pilot: hours of boredom interspersed with moments of sheer terror. The hours of boredom are all the work of setting up for each test, and the moments of sheer terror come when your precious hardware gets subjected to such violent treatment.

The uncanny thing about a vibration test is how much it sounds like a rocket launch. Of course, that makes perfect sense when you think about it. The vibration facility is really nothing other than a gigantic loudspeaker, and the electronics that make it work are nothing other than a gigantic synthesizer. And the song that the synthesizer was playing last week was simply the sound of a Delta rocket heading for space.

We passed nearly all of the tests. Both instruments passed the landing test, and one of them passed the vibration test. The other one had an electronics board that wasn't quite fastened down right, and it shook loose during vibe. This is why you do tests! We'll fix it up and test it again in a few weeks.

It's crunch time for the Mössbauer Spectrometer. The nasty "ringing" problem we had last week has definitely been solved, so it looks like we dodged that bullet. The latest problem is that one of the Mössbauer electronics boards -- the part of the instrument that lives inside the rover body -- is getting a little flakey on us when we run it at cold temperatures. It doesn't look like a serious problem, but it's going to take a little time to fix it.

The Mössbauer sensor heads, though -- the parts that go out at the end of the rover's arm -- are ready to go. So we're going to deliver the instruments to JPL in two parts. This week Goestar is going to come over from Germany with the sensor heads, and spend the week at JPL putting them through a bunch of tests. We're going to shake them as hard as they'll be shaken during launch, whack them as hard as they'll get whacked when we land, vibrate them like they'll vibrate when the RAT is working, and so on. And once that's done, the sensor heads will be officially ready to go to Mars. Meanwhile, back in Germany, the rest of the guys will be running down the last of the electronics problems. So then, a few weeks from now, we'll get to do the same thing all over again with the electronics boards.

We had what looked like a pretty serious problem with our Mössbauer Spectrometers this week. We're now doing thermal testing, which means making sure that the instruments work properly at the temperatures that we'll actually see on Mars. The Mössbauers were behaving fine at room temperature, but when they got cold they started doing what we call "ringing". Each Mössbauer has a little drive system inside it that vibrates back and forth about 20 times a second. It's supposed to vibrate in a controlled way, but when it "rings" it's sort of like what happens when you put a microphone near a speaker and get feedback... it vibrates out of control. And if that happens, we don't get Mössbauer data.

At mid-week it looked like we might have a pretty bad problem, but the guys in Germany -- Goestar and Bodo and Daniel -- have really hunkered down and worked hard on it over the past few days and nights. They traced the problem to one part in the electronics, and with a change to that part one of the two instruments is now behaving itself down to temperatures as cold as -120 C. We still have to finish the testing and then fix the other one (once everybody catches up on some sleep!), but right now things are looking pretty good.

This is it. On Monday, February 25th, we're about to begin ATLO: Assembly, Test, and Launch Operations for the rovers.

Every space project has several critical phases in its life, and ATLO is one of them. ATLO is the process of actually putting the flight hardware together, making sure it works, and shooting it off to wherever it's going. For us, ATLO starts now.

It's a funny feeling. On the one hand, we barely feel ready for it. Time is precious, and a few more weeks to get better prepared for a job this difficult would be nice. On the other hand, we've been waiting for this for so many years, it feels great to finally be doing it! These rovers have been in the planning stages -- and have been at the very center of our professional lives -- for more than six years now. And seeing the real flight hardware finally start coming together after all that time is a thrill that far outweighs whatever nervousness we might have.

Our schedule is so tight that even minor delays seem major, and we had a bunch of them this week. The camera electronics got set back a week because one of the cables in the design was bent a little more sharply than it ought to be, meaning that we had to change things once again to fix it. There's a minor problem with noise in the APXS electronics that's had everybody working crazy hours in Germany. And for some weird reason we've been having a terrible time lately just trying to ship stuff around. Electronics parts are "in the mail" for what seems like forever on their way to Mainz. Magnets on their way from Copenhagen to LA get hung up in Paris. Calibration targets vanish for a week while being shipped between Arizona and Colorado. It's maddening. Nothing's gotten lost permanentely, and if time weren't so precious, stuff like this wouldn't matter at all. In fact, the delays really haven't been all that serious. But when something's moving as fast as this project is, it can seem like the rest of the world is going in slow motion.

We had a great week -- Mini-TES 2 passed its vibe test! Vibration testing is one of the crucial events in the life of any piece of space flight hardware. You can read more about vibe testing on our Science Bites page. We had shaken Mini-TES 1 pretty hard some time ago, so we knew that the basic Mini-TES design was solid. This vibe test on Mini-TES 2 was what is sometimes called a "workmanship" test. We already knew it was designed well; this test showed us that this particular Mini-TES is also put together well. The guys in Santa Barbara put it through its paces right after the vibe, and everything checked out fine.

So now it's on to the next test...

We made a major change to our landing site plans this week. A few months ago, we narrowed our choices down to just four places on Mars, and since then all four have been under some really intense study. Unfortunately, that study has turned up what could be a real problem with one of them.

The one that may be dangerous is the one we call Athabasca. It's a great site, but recently we've looked at some radar data that look really scary. You can bounce radar signals off of Mars from Earth, and when you do the signals that come back from Athabasca look like what you'd expect if the surface there were really rough. Not only that, but the roughness seems to be just about the same size as our wheels are. That's not good!

To be honest, we're not 100% certain what the radar data really mean, and we can't prove beyond a shadow of a doubt that Athabasca's not perfectly safe. But it looks scary, and we're not about to take any big chances with these rovers. So Athabasca is off the list, and we've replaced it with a site in a place called Isidis. We still have several months before we have to pick the final two sites, and the work continues.

Murphy's Law seems to be one of the guiding principles behind space missions, but every now and then something goes right. We had two of 'em this week.

Several weeks ago, we discovered that we had a problem with Mini-TES number two. The instrument worked fine in most ways, but the results we were getting were more "noisy" than they should have been... a little like too much static in a TV picture. The guys in Santa Barbara tracked this one down and thought that they had fixed it. We did some tests last week, and it turns out that they did more than just fix it... Mini-TES 2 is now even less noisy than Mini-TES 1 is.

The other one had to do with our cameras. For a couple of months now we've been wrestling with a problem where the voltage of the electrical power delivered to the cameras wasn't coming out quite right. We found a fix, but it didn't look like a very elegant one. Even though it clearly would work, it looked like it could really increase the amount of power it would take to run each camera. And electrical power is really precious on a solar-powered rover! The JPL electronics guys have worked really hard to fix this, and this week we did some tests that showed that in reality the power usage of the cameras will be much lower than we had feared it would be... which means we can use that extra power to take more pictures.

So this week was a combination of some great design work and a little bit of luck. Occasionally things go your way.

It's always something. This week we discovered another one of those dumb mistakes that could really have gotten us into trouble us if we hadn't caught it now.

One of the things we have to be very careful about is what's called "Planetary Protection." For us, Planetary Protection means not contaminating the surface of Mars with bacteria from Earth. There are all kinds of good reasons to be careful about this!

One way to do Planetary Protection is to sterilize the hardware we fly, and we do that with much of what we build. But some things, like electronics, are not easy to sterilize. So the other thing we do sometimes is clean our hardware carefully, and then seal it up really tight so nothing bad can possibly get out.

Of course, it's not that simple. Everything is full of air when we launch from Florida, and the air has to get out as we ascend into space. We can't let any bacteria leak out with the air, so we put special filters in place that let the air out while keeping the bugs in. And it all works really well.

But there's a problem, as we just learned: These filters don't just let air through them... they can also let light through them. And we have them in our cameras! Let extra light leak into a camera, and you can take some very bad pictures.

So now we're designing little "hats" to go over the filters. Air can still get out, but light can't get in. Problem solved.

But like I said, it's always something...

The whole project is about to shift gears pretty soon, in a very big way. In only about a month, we start what's called "ATLO"... short for "Assembly, Test, and Launch Operations". ATLO is NASA-ese for the process of putting it together, making sure it works, and shooting it off.

And that's what we're about to start doing. For a very long time now we've been planning, designing, and building bits and pieces of things. The planning is finished, the design is all done, and lots of bits and pieces are built. So starting next month, we begin to put it all together.

This shift to the start of ATLO is one of the biggest changes that a space project goes through, so of course we have to have another review before we do it! Next up is our "ATLO Readiness Review", where we try to convince a review board (and ourselves) that we're ready to get on with it. The past week has mostly been spent getting ready for this review, and the next one will as well.

After all these years, it's going to feel good to start actually building these things.

We've got an awful lot of testing to do, but sometimes real-world problems get in the way. This was supposed to be the week that we were going to do some important vibration testing on our Mössbauer spectrometer. It didn't work out that way. Everything needs maintenance and refurbishment from time to time, including vibration test facilities. We've had to postpone tests that we were ready for a couple of times recently because the test facilities weren't ready for us. It's easy to get a little impatient when this happens. But that's why we've got margin in our schedule!

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