Donna Shirley Interview (page: 6 / 7) Mars Exploration Program	Print Interview

What did it feel like when you guys landed successfully?

Get the Flash Player to see this video. Donna Shirley: It was great, it was absolutely great. We have video tape of the team jumping up and down and screaming and hugging each other. And, that was another thing that people really identified with Pathfinder because people were willing to show emotion and were willing to jump up and down and they weren't very -- they weren't wearing suits and ties. They just looked like real people.

A lot of that was a reflection of Tony Spear, who's a very emotional kind of a guy. He's a very charismatic kind of leader. His ability to tightly control budgets and schedules and everything is not strong, but boy, he can get a team around him and really get them fired up, and that's what he was good at. So when this team landed on Mars it was great.

Get the Flash Player to see this video. I was disappointed in a way because I had 25 years of experience communicating with the media and all that sort of stuff, so I was the one that was out in front of the TV cameras. My boss and I, Norm Haynes, were doing that, so that the reporters wouldn't be in bothering the people flying the mission. So, I'm out in front of CNN cameras and all I can see is this little monitor and it's a really hot, bright July 4th day, and so I can't see very well. And the anchor's saying, "What's going on? What's going on? I can't see what's going on! Get me a sunshade! And so I'd see them jumping up and down and I'd say, "Well, they must have made it." And, then we'd hear something on the earphones. So, I was experiencing this kind of vicariously, but I mean, it was just an incredibly emotional moment.

[ Key to Success ] Passion

Then we had trouble with the rover. You know, mothers love all their children equally, but the littlest one is kind of your pet. So, I was still very fond of the rover and the rover was having trouble getting off the petal. There's this petal with solar rays on it and the air bags were bunched up and blocking the ramp that the rover had to get off. So they had to pick up the petal and pull the air bags in some more and then put it down.

Then we were having problems communicating between the lander and the rover. It turned out the sun went down before we could get the rover off. So I had to spend a whole night wondering, what's going to happen? The next day, they fired up and the rover got off. It was really something.

Get the Flash Player to see this video. The lander camera could take pictures of the ramp the rover was coming down. And, there was a young scientist named Justin Mackie, who had figured out how to program the camera to turn, so that it would catch the rover as it was doing things. So, it would make a little -- like a jerky movie. And so, the camera -- the first picture comes back and there's just the ramp sitting there. And I'm thinking, "Oh, my God, the rover didn't get up," or whatever. And then, the next picture and then all of a sudden you see the ramp bend and then the rover comes into view. And then -- so there's six images for it to get down on the ground. And, this guy from Mission Control, Art Thompson says, "Six wheels on soil." And it was just the greatest experience, it was a terrific, really terrific high.

[ Key to Success ] Passion

Scientists often say they learn from failure, and it seems to me that this rover was a great success. What have you learned that will apply to the future rovers?

Donna Shirley: Every time we do a mission we have things that fail, no question. Mars Observer's failure had a huge impact. We had not lost a complete mission for 27 years. It was a shock and it forced them to reevaluate some of the things they'd done.

For instance, the belief system was, "Contractors build earth orbiting spacecraft, so just buy an earth orbiting spacecraft and ship it to Mars." It turned out that the conditions are very different. That was one thing that led to the failure. Also they said, "You can carry lots and lots of instruments." We said, "No, we really can't." They said, "Oh, sure you can," and we overran the budget because the instruments were too big. So you learn something from everything.

Out of the ashes of Mars Observer rose the Mars Exploration Program. Instead of doing one giant orgy of exploration every 20 years, we'd better do it every 26 months, when the planets line up right. We'll do two, so if we lose one, it's not such a big trauma.

Mars Global Surveyor was the first one of the Mars Observer replacements. Pathfinder happened to be going at the same time, so we had an orbiter and a lander. Now, from Pathfinder we learned that it's possible to use air bags to land on planets, but it also turned out that they were much heavier than we originally thought. We're being forced into smaller and smaller launch vehicles, so we can launch less and less mass. For the '98 lander, we're using retro-rockets, like Viking used, because they don't weigh as much.

So we learn something even from our successes. The air bags were incredibly successful. Now if we ever want to go someplace that's really rugged, we can go back and use the air bags. We'll have to use the bigger launch vehicles and that's the way it is.

From the rover we learned that small rovers really can operate. Nobody believed this, but the microelectronics revolution over the last 20 years has enabled very small computers, very small sensors, charge-coupled device cameras and things like that. We used a lot of commercial stuff in the rover because we could. Viking cost so much because they had to invent everything. Because 20 years ago there weren't small computers, there weren't good sensors, nobody knew how to build a mass spectrometer that would fly to Mars and so on. Now we can take advantage of the technology that's been developed by the military and the commercial technology. That's how we were able to do Pathfinder and the rover so cheaply.

There's still a problem because these technologies are not designed for space. We were lucky Pathfinder flew during a low solar cycle, low sun spot time. Now we're going into a high solar cycle and there's a lot more radiation and charged particles around. Are commercial parts qualified for this harder environment? Probably not, so do we use commercial parts and if so how do we protect them? There are always new challenges.

But we learned that small rovers work, they can do useful science, they can carry instruments. It's possible for a fairly stupid robot to really do something. The rover has about the same intelligence as a bug. When a bug comes up to a rock, it doesn't say, "This is a rock, I will now look over here and go around this rock." The bug keeps bumping into it until it gets around it. That's kind of the way the rover works, except that we don't have to touch the rock, because the rover has laser light stripers in front that stripe light out onto the ground. It has cameras and it has a computer brain. So the cameras look at the stripes and if the stripes are nice and flat and straight, the computer interprets that as, okay, you can move ahead, it's safe. If the stripes wrinkle, then the computer knows there's a rock, and then it's programmed to turn and keep going until it can no longer see this obstacle. Then it will turn around it and go back in the direction it was told to go in the first place, very simple intelligence.

If the rover tilts suddenly, or tilts past a certain degree it stops. Our first Mars traffic accident was when Sojourner was backing up to Yogi, the big rock. It's really difficult to calculate exactly how many turns of the wheels you need, because you slip a little bit in the dirt. Jack Morrison, the operator, backed up a little too much, and one of the rover's wheels went up on the rock. As soon as the wheel gets too tilted, the rover knows to stop.

Get the Flash Player to see this video. We were stuck with this wheel on the rock. And then, we had a communication problem with the lander, between the lander and the earth. And so, we couldn't get commands into the rover because the rover only talks to the lander, and the lander talks to the earth. So, we sent commands to the rover, "Okay, move forward a little bit," but they didn't get there. So, here's the rover, wheels stuck on the rock, and they were trying to take -- they'd just finished taking one panorama called the "Gallery Panorama," and now they were going to take the "Presidential Panorama." This was going to be better. More colors, you know, better resolution. Here's the rover, with the wheel up on the rock. And, I'm saying, "You can't send a picture to the President with a rover with her wheels stuck up on the rock!" And the guys were kidding me because they say, "See, it's a male rover after all."

Fortunately they were having enough communication problems rushing to get this picture for the President. By the time they actually took a picture of that area the rover was already down and they'd gotten the communication problems worked out. So it was a nice decorous picture of the rover in the big panorama that everybody sees.

Another thing we learned was that operating on Mars with solar power is really difficult. For one thing it's a 24 hour and 37 minute day, so you're in night a lot of the time. That means you have to have batteries. Batteries don't like cold weather and it's very cold on Mars. So there's all kinds of problems with how you power the thing and keep it warm.

There's another thing we discovered. The rover had a little a solar cell that was covered with a cover. So, once a day we'd move the cover off the solar cell and measure the difference between the power coming from the clean cell and the dirty cells that had dust falling on them. We discovered that the solar panel was degraded by .2 percent per day just from dust filtering out of the atmosphere and falling on this solar array. So we don't know how to make a mission on Mars last more than 90 days, just because of the amount of dust falling. We don't know how to design little brooms to clean off solar arrays and we don't know if it's because of the static electricity that's generated. So there's a whole new challenge that we have to solve for the next set of missions.

You learn things. That's the whole idea of the program. You learn something from this mission, you apply it to the next mission. That's how risk management is done. It's a gradual process of building up your knowledge, instead of trying to do everything at once.

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