Martian Chronicles X: On Our Way
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.
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.
February 15, 2003
This week we put to rest what may have been the worst remaining problem that stood between us and launch.
This one was looking very nasty for awhile. Back in December, we put the whole MER-2 rover into a big thermal chamber and took it down to cold martian temperatures. Almost everything worked right, but one thing was very, very wrong. When the rover got really cold, the pictures from one of our two Pancam cameras got bad. In fact, they were worse than bad, they were terrible. Imagine a TV picture with static so bad you can barely tell what you’re looking at. That’s what some of them were like. It only happened in that one camera, and it went away as soon as we warmed things up a bit. But it was pretty scary, because we didn’t know what was wrong.
|Viking image of Gusev Crater, an ancient proposed lakebed that will be targeted in forthcoming Mars Exploration Rover mission.|
We chased this one for a long time. The breakthrough came a few weeks ago, when Leo Bister at JPL took a really careful look at the cables that run to all the cameras at the top of the rover’s mast. Something just didn’t seem quite right to him, and when he dug into it he realized that we had built the cable wrong. That cable has a bunch of pairs of wires in it, with the pairs of them carefully twisted together. Problem was, the wrong wires had been paired up when they were twisted, letting signals from the camera become contaminated by signals in other wires. It was the kind of thing that would get worse when the cable got cold, and it was also the kind of thing that could really mess up a picture.
This had to be it, but you can’t be sure until you test. We built some new cables, replaced the old ones, and late last week we put the whole rover back into the chamber again, cooled it down, and held our breath. It worked. Every picture was clean and flawless, even at the coldest temperature. It was a huge relief, and a nice piece of detective work by Leo.
February 22, 2003
It’s that time again: Thermal-vac testing, this time for the MER-1 rover. Before each rover goes to Mars, we have to put it through all its paces under martian conditions. This means putting into a big "thermal vacuum" chamber, pumping the air out, cooling the walls down, and filling the chamber with a little bit of very cold gas to simulate the martian atmosphere. We then make the rover do just about every trick it knows, including operating all of the science instruments.
We did this with the MER-2 rover back in December, and it was a pretty exhausting experience. Thermal vac runs 24 hours a day until it’s over, and MER-2 thermal vac went on for something like ten days and nights. MER-1 has just gone into the chamber as I’m writing this, and the action should continue all this coming week. The first big hurdle will be to make sure that the Pancam "speckle" problem that hit us on MER-2 is really gone. And after that, we’ll just rock around the clock until all the tests are done.
March 1, 2003
Thermal vac testing of MER-1 is almost over. It’s been quite an experience. Back in December, when we put the MER-2 rover into a thermal vacuum chamber and ran it under martian conditions, it was quite a struggle. We got all the data we needed, but a lot of things also went wrong. The worst of them was the "speckle" problem in the right Pancam camera, which we finally killed off in a test on MER-2 last week.
For MER-1, though, thermal vac testing this past week has gone much more smoothly. Everything has gotten better over the past couple of months: hardware, software, and people. There was no speckling in the Pancam on this rover. We got tons of Mini-TES data, and the data showed that this instrument is just as good as the one on MER-2, or even a tad better. And we did the first full-up test at martian temperatures of the fix to the Mössbauer Spectrometer problem that turned up months ago. The Mössbauer data looked great, so that one is behind us now too.
As in the last test, two of the real standouts were the Instrument Deployment Device also known as the rover’s arm and the Microscopic Imager that it carries. Here’s a sequence of five Microscopic Imager pictures, taken as the arm slowly moved the camera to bring things into focus. Pretty cool, huh? Now imagine what it’ll be like next January when this same camera is taking close-up pictures of martian rocks.
March 8, 2003
Every now and then you catch a lucky break. We caught one this week that we still don’t completely understand, but we’ll take it. Our Rock Abrasion Tool (also known as the RAT) uses diamond grinding heads to wear away at martian rocks. Even though diamonds are the hardest materials known, they can still wear out, and we’ve been very concerned about how long the RAT grinding heads will last on Mars. We’ve done a lot of testing in the laboratory, and it looked like the RAT would do fine if martian rocks are soft. If the rocks turn out to be really hard, though, it seemed that the RAT would make it through just a handful of grindings before wearing out.
The big question, of course, was how things would work under the very cold, dry, low-pressure atmospheric conditions on Mars. We put a RAT into a test chamber recently, took it to real martian conditions for the first time, and got a very pleasant surprise. The rate at which our diamond-studded teeth wear away slowed way down! We’re still figuring out why, but it turns out that when you put this martian RAT into its natural environment, its teeth don’t wear down nearly as fast. So we should be able to grind into as many rocks as we want to on Mars, no matter how hard they turn out to be.
March 15, 2003
This week marked one of the most important milestones since we started this thing more than seven years ago. The second MER rover and its Athena payload arrived in Florida.
Since the summer of 1999 we’ve been putting weekly news updates on this web site. We’ve had a lot of ups and downs over that span, including some times when it looked like maybe we weren’t ever going to get our payload to the launch pad at all. And now, after years of effort by hundreds of scientists and engineers, everything is at Cape Canaveral. It’s an incredible feeling. This picture, taken by Goestar Klingelhoefer, shows the last of the trucks rolling through the gate at Kennedy Space Center… with me on my cell phone giving the news to the folks back home.
We’re now less than eleven weeks away from our first launch.
March 22, 2003
We’ve just been through two of the toughest weeks we’ve had in the past couple of years.
Problem number one was with our Mössbauer spectrometer. Each Mössbauer instrument is like four instruments in one… four separate sensors that each return data. When we got them to Florida, the MER-1 Mössbauer looked fine, but one of the four sensors on the MER-2 Mössbauer had gone totally dead. We spent almost a week troubleshooting it, and we finally traced the problem to one tiny electronic part, called a resistor, that had failed. We managed to figure out why it failed, and we confirmed that the problem shouldn’t affect any of the other sensors. Roberta Cerda flew out from JPL, put the broken hardware under a microscope, and fixed it. She is a true artist with a soldering iron, and the instrument is now ready to go.
Problem number two was with our APXS instrument, and this one looked even worse. Six hours into a test at JPL, the MER-1 APXS just plain died. Or at least it sure looked like it had. It suddenly stopped working, and when we made some quick measurements it was clear that a short circuit had developed somewhere inside the instrument. That kind of thing can be fatal for flight hardware, and most of us were pretty convinced we were going to have to fly one of our spare instruments. But Ralf Gellert didn’t give up on it. He took the instrument apart, and he found the problem. A tiny sliver of aluminum, probably stripped from a small screw, had gotten wedged in just the wrong part of the instrument and caused the short. That’s why we do tests, to find that kind of problem. The instrument wasn’t damaged, and when he took the sliver out everything started working fine again. You can bet we inspected the inside of the instrument really carefully to make sure there was nothing else like that inside it! So that one’s ready to go too.
When problems like this happen a year or two before launch, it can be easy enough to deal with them. But when they happen now, with both spacecraft at Cape Canaveral, it’s a different story. We really dodged a couple of bullets this week.
Ten weeks to go…
March 29, 2003
The Athena payload for the MER-2 rover is done.
At some point you have to be prepared to say goodbye to your hardware on a project like this, and that time is just about here. We have taken the last data we’ll ever take on this planet with the instruments on the MER-2 rover. We stowed everything for launch this week. The mast is locked down tight against the rover deck now, and the arm is tucked up against the front end of the rover. Our instruments have been turned off, and they’re going to stay that way for awhile. The next time we talk to them, the rover will be in deep space, on its way to Mars. And the next time we move the arm or the mast, or take any real pictures, we’ll be down on the martian surface.
That’s MER-2. MER-1 is still very busy, taking pictures, driving around, and going through its last bit of testing in Florida before we stow that one for launch too. But in another week or so, everything we’ve worked on for the past seven years is going to be ready to head into space.
Nine weeks until we launch…
April 5, 2003
It took awhile, but we finally did it. We finally got a chance to take a picture that shows what our Pancam cameras are really capable of.
|The new Pancam design has a camera bar that contains Pancam and Navcam (navigation camera) heads. A "visor" changes the elevation of the cameras so the rover can look up or down.|
Credit: Cornell University
We’ve been incredibly busy with pre-launch testing, and there hasn’t been much time to just play around with the hardware and show what it can do. But this past week, during an overnight "graveyard shift", Justin Maki pretty much had the MER-1 rover all to himself. He put the opportunity to good use, taking the first really big panorama that we’ve gotten with Pancam. We’re calling it the Midnight Pan, because that’s when Justin took it.
Here it is. It’s a full 360 panorama around the room at Cape Canaveral where the rovers are being readied for flight. You can see the solar arrays of the MER-1 rover itself at the lower left and lower right corners of the image, and a whole lot of other hardware all over the room.
This is just a low resolution version of the image, though… we had to shrink it down by a factor of eight in both directions to make it small enough to download. In order show what full resolution looks like, we’ve drawn five red boxes on the image. Click on any one of them, and the full-resolution version of the image will pop up. The whole image is that good.
There still are some things about this picture that aren’t like our Mars images will be. We did just a quick-and-dirty job of putting the individual frames together, so you can see "seams" in the image, particularly for things close to the camera. We’ll take care of that in the martian images. There are some weird glints in this image off of really shiny metallic surfaces; we don’t expect to see stuff like that on Mars. And of course on Mars we’ll take a lot of our images in color rather than black and white. Still, this gives you a feel for the kind of look at Mars that Pancam will give us.
Less than eight weeks until our first launch…
April 12, 2003
What a week! We passed two of the biggest milestones in the history of our project… not just in the same week, but on the same day.
The first milestone is that the Athena payload is now done. We have been working on this thing since 1995, and on Thursday of this past week the last piece was put in place. Both masts are stowed, both arms are stowed, and all the testing is done. The next time any of our hardware gets deployed, it’ll be on Mars.
The other milestone is that NASA has selected our landing sites. Not only that, they’re the two sites that practically everybody in the Mars science business has been hoping we’d get: Meridiani Planum and Gusev Crater. Meridiani is a place where there’s a large concentration of a mineral called coarse crystalline hematite… stuff that on Earth usually forms in the presence of liquid water. And Gusev is a large impact crater with an big dried-up riverbed flowing into it. Long ago there was a lake in Gusev Crater, and the crater must still be full of sediments. They’re both great sites… in fact, they’re the two best sites you could possibly find for a mission like this. We’re thrilled with them.
So now it’s a race to the finish, trying to get both spacecraft to their launch pads on time. We have less than seven weeks to go before our first launch.
April 19, 2003
It’s been a pretty crazy week. We’re getting very close to launch now, and the focus is starting to shift from our spacecraft to our rockets.
Of course, the spacecraft story isn’t over yet. You saw in a news flash here last week that the spacecraft team down in Florida found a wiring problem that required taking both rovers apart and fixing an electronics board inside them. That work is done now, and it went very smoothly. But it set us back a little, and the MER-A launch is now scheduled for June 6th, instead of the original date of May 30th. It’s a headache we could have done without.
The rocket story isn’t entirely simple either. For MER-A, it’s pretty straightforward. MER-A launches from pad 17-A, which is clear now and ready to have our first rocket put on it. For MER-B, though, which is due to launch on June 25th, it’s more complicated.
Right now, pad 17-B, which is where MER-B will launch from, has somebody else’s rocket on it. It’s the launch vehicle for a mission called the Space Infrared Telescope Facility, or SIRTF. SIRTF is a very cool mission… a giant telescope to scan the universe at infrared wavelengths, just like the Hubble Space Telescope has done at visible wavelengths. Thing is, there’s a problem with one of the nine solid rocket motors on the SIRTF launch vehicle. It’s a minor problem, but NASA is playing it safe, and they’ve decided not to launch SIRTF until that motor can be replaced. Replacing a motor isn’t hard, but it takes time, and time is something the SIRTF team doesn’t have… because of us.
A mission like SIRTF can launch at just about any time, as long as the rocket and the spacecraft are ready. But a Mars mission like MER-B has to go in a specific "launch window": a brief period of time when Earth and Mars are aligned properly to get from one to the other. Our launch window is coming up soon, and that doesn’t give the SIRTF guys enough time to fix their problem and get off the ground before we need to move onto pad 17-B. We’re the ones with the tight schedule, but it’s SIRTF that has to take the hit, getting bumped to late summer to make room for us. We feel bad about it… SIRTF has been waiting for their ride into space even longer than we have. But Mars won’t wait. So SIRTF goes back to the hangar for awhile, and we’re up next.
April 26, 2003
|Artist conception of dramatic airbag landing Credit: NASA.|
It’s pretty much impossible to have a week of nothing but smooth sailing on a project as complicated as this one, but the past week was about as close as we come. The science payload on both rovers is all done. The fix of the cable problem that made us delay our first launch a couple of weeks ago is done too. And it went so well that the launch date for MER-A has moved forward by a day, from June 6th to June 5th.
The second rover is on its lander now. The first rover is even farther along, folded up inside its lander and about to be tucked up inside its protective aeroshell… where it will stay until it falls out of a pink sky over Gusev Crater next January.
And coolest of all, our first rocket is coming together now. The first stage of the MER-A launcher was put up on launch pad 17-A at Cape Canaveral on Wednesday, and the second stage will follow shortly. So there’s most of a real Mars rocket down in Florida now, almost ready to have our first spacecraft to put on it.
May 3, 2003
The rovers are all done, the rockets are on the launch pads, and it’s time now for the science team to turn our attention from how to build these things to how to operate them.
For years now, our focus has been on building the Athena payload and getting it to the launch pad. But now, with all that behind us, we need to start earning our martian drivers licenses. It’s a complicated process. These are very complex machines, and operating them will take a team of more than a hundred scientists working around the clock for months, starting next January.
This coming week, we’ll take one of our first steps toward learning how to do it. It’s called a "thread test". Think of it as being like the first walk-through by the cast members in a play. We don’t know all our lines yet. We don’t know where the props are. And we sure aren’t ready to perform in front of an audience. But over the next week we’re going to try walking slowly through all the things that we’ll have to do over the course of a couple of martian days once our rovers are on the surface.
All of this is going to happen in the brand-new MER Project Mission Support Area at JPL. The paint’s barely dry yet! They were still moving furniture in late last week. So it’s not just the scientists that aren’t ready yet, it’s the facilities too. We’ll start working the bugs out this week.
May 10, 2003
Well, we had our first big rover operations test this week. It wasn’t pretty, but it was a lot of fun. This was the first test in which we actually walked through the procedures that we’ll use to do science operations once the rovers are on Mars. The thing that made it really interesting was that we did it in our new MER Mission Support Area at JPL. It’s a great facility, but everything was very new to us. It was sort of like the first day in a new school… you could almost hear people saying "Where’s my homeroom? What’s my locker combination?" It took a little while to figure out where everything was.
Over three days we practiced two martian days, or sols, worth of surface operations. The first sol was an "approach sol" where we drive the rover to a rock that we’ve selected. The second one was a "spectroscopy sol" where we use the instruments on the arm to look at the rock in detail. The first sol was pretty ragged, frankly… everything was new and we had a lot to learn. The second sol went a lot better, and that one probably would have actually worked out pretty well if we had been doing it for real on Mars. So we’re learning.
This kind of rehearsing is most of what we’ll be doing over the next eight months or so. And by the time we land next January, we’re going to have to be very, very good at doing geology with robots on another planet. It’s a somewhat specialized skill, I guess, but it’s one we’re going to have to learn.
May 17, 2003
It’s getting very close now. The rockets are on the launch pads, and you can almost feel the pace accelerating. This week, the solid rocket motors were put onto the outside of the Delta II rocket that will launch MER-A. This picture shows our first rocket on pad 17A at Kennedy Space Center. In the background you can see three of the white motors already on the vehicle. One more can be seen on the cart in the foreground, about ready to go onto it. Once everything is all put together, there will be nine of those white motors, all clustered around the base of the rocket. See our launch pages to learn more.
|Rocket-camera, Delta launch rocket for MER mission, as imaged during Monday’s successful take-off. Opportunity could have launched as late as July 15th, with a 24 hour turnaround to troubleshoot any problems with its Delta rocket. But after the fifteenth, a stand-down of four years would have been needed for the same mission profile to reach Mars as efficiently. In a nail-biting series of finishing fixes, five launch delays pushed the take-off to late Monday night, when its spectacular take-off finally illuminated the Florida Space Coast.|
Of course, you’ll notice that something’s not quite right in that picture… there’s no spacecraft on top of the rocket yet! So far, only the first and second stages of the vehicle are out on the launch pad. The MER-A spacecraft will be mated with the third stage late this coming week. It won’t be until early the week after that that it gets taken out to the pad and hoisted on top of that beautiful blue-green spaceship you see in the picture.
May 24, 2003
We’re less than two weeks from our first launch now, and the final preparation of the hardware for flight is almost done. The big event of this past week was the mating of the MER-A spacecraft to the third stage of the Delta II rocket. This isn’t done out at the launch pad. Instead, they bring the whole third stage of the Delta indoors, into what’s called the Payload Hazardous Servicing Facility at Kennedy Space Center. The fact that they bring a whole live rocket motor into the room is why it’s called the hazardous servicing facility! The MER-A spacecraft, which will be the first to launch, was mated to the third stage on Friday, without a hitch. And early this coming week the whole spacecraft-plus-third-stage "stack" will be driven slowly and carefully out to launch pad 17A, hoisted up the tower by a big crane, and mounted on top of the rocket.
May 31, 2003
This is it: show time for MER-A. The spacecraft is on the launch pad, healthy and ready to fly. The protective fairing that goes around it at the top of the rocket was put in place over the weekend. We’re working our way through all the pre-launch paperwork and reviews… you can’t be too careful about this kind of thing! But once that’s all done, we’ll be ready to go. And when it happens, years of work in preparation for flight will come to a thundering conclusion as our first Delta II climbs off of pad 17A. I know what it’s going to look like, since I’ve been to Delta launches before. But I have no idea how it’s going to feel.
June 7, 2003
|Delta launch rocket for MER mission.|
Well, we scrubbed today. That happens a lot in the rocket business. A scrub is when you have to cancel a launch late in the countdown and try again another day. Scrubs happen for all kinds of reasons. Usually it’s weather, and that’s what got us today.
Early this morning it was beautiful on the Florida coast. I watched dawn come up over Pad 17A, and as the sun’s first rays hit the rocket it was a lovely thing to see.
It would have been nice if we could have gone right then, but you can’t just launch a rocket whenever you want to. Because the Earth is always spinning, you need to wait until it’s at just the right point in its spin to launch it. Otherwise, you’d be headed off in the wrong direction. For us, the right time of day today to go to Mars was 2:05:55 PM Eastern Daylight Time. But when the weather guys looked at their radars a couple of hours before liftoff, they could see some very bad stuff headed our way, and a scrub was called. And sure enough, when launch time came around there were some very nasty clouds hanging over the pad.
You might think it’d be frustrating when something like this happens, but it really isn’t. We’ve waited so long to fly these things that another day doesn’t seem like much. And with $400 million worth of hardware out on the pad, the thing we really don’t want anybody to do is take chances. So we’ll try again tomorrow.
June 10, 2003
Spirit lifted off into a hazy blue sky right on time this afternoon. The Delta II gave us a beautiful ride, and Canberra picked up the spacecraft on schedule. Last I heard we had good attitude, good power from the arrays, batteries coming up, and strong telemetry. We’re on our way to Mars.