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| Our Future in Space |
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Peter Smith Titan was scary. I was lucky enough to be in the control room over in Germany, at Darmstadt, where they have the European Operations Center. Of course everybody knew exactly what time the signals were supposed to arrive. As that time came and went, the signals weren’t arriving. Poor Marty was pacing. On the probe there are two antennae, A and B. They were sending redundant signals, and the idea is, if you lose one, you don’t lose the whole mission. After checking the command sequence, they finally realized that somebody forget to turn on the receiver to receive the signals from channel A. They’re realizing this a few minutes after the signals were supposed to come: “I don’t see the command to turn on the receivers.” Everybody in the room wanted to know, “What about B?” “Well, that’s turned on, but we’re not getting anything.” I think six minutes went by, and then the signals started to come. In those six minutes, we died a thousand deaths. All the reporters were there, people from all over Europe and the United States, everyone waiting to see data coming down. Finally, of course, data did come down on side B. We’re looking at the pictures, and the strange thing was, the surface images looked like the coast of Italy. There was a lake—little rivers coming down off a hill into what looked like a lake. That’s unbelievable. What a thrill. You don’t know what to expect from Titan but you don’t expect rivers flowing down hills into lakes. Martin Tomasko Well, with the pressure of going to reviews, and the pressure of a different team of guys actually doing everything a different way, somebody left out a command. The command to select the ultra-stable oscillator was included, but the command to actually turn the receiver on was omitted. So now we’ve got two receivers, but only one is working. The other receiver just isn’t turned on. |
We’ve got all our redundant data, because it worked on that channel, but on the images, we’ve got 350 instead of 700. Even a little bit worse for us was the fact that the probe says, “Hey, both channels are working peachy. I’m just going to divvy them up between here and here and here and here.” That means we’re missing every other image. My images aren’t a consistent set the way I was expecting, but have holes in them—half the images are missing. That makes my life, trying to put those images together to make that nice mosaic, a little bit difficult. In fact, it makes it especially difficult because, at the same time, the probe dynamics in this new atmosphere was not what was expected. The probe is bobbing and weaving much faster than what was expected, and at higher rates. The probe rotated in the intended direction for first ten minutes, and for the next two and a half hours it rotated the wrong way. It wiggled and shook and did all of these things. Now you’ve got this set of 350 images that you’ve got to put together. It’s like a puzzle. You don’t have a picture on the front of the box; you don’t know what it’s supposed to look like. Half the pieces are missing. Every time the probe tips and turns, the footprint of the image on the ground changes, so the pieces change. The shape of the pieces change, half the pieces are missing, and the clock is going around backwards so you don’t know where you are. The housekeeping data to tell you where the image is pointed isn’t there. So to prevent people from being too proud, the dynamics were really screwy, and somebody just left out the command to turn on the other receiver. But we got most of the data that we needed. The whole story is, the Lord gives and the Lord takes away. It’s only by the grace of God that you get what you want. We planned on getting about five times what we needed, and we got about 95% of what we needed. So we almost have the whole mission done exactly right. |
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