 So for me, one of the great moments in life, you know, other than birth of my kids, getting married, you know, big things like that, was the time we were able to send a measurement system, an instrument to Mars orbit with the very creative name of Mola, the Mars orbiting laser altimeter. Mola happens to also be apparently a Latin name for a fish, but that's another thing. So we had this dream, not as big as the dreams of the great, you know, political leaders of this country, but a dream to measure the landscape of Mars at a scale where we could tell how it got to be the way it was, at scales where you could also land on future systems. And that dream was one of my first dreams when I got to NASA. I knew I needed that. I was inspired to ask that question by my professors at multiple universities. So I got together and I said, we've got to measure it at these scales in this way. And the engineer said, well, have you thought about this, Jim? I said, I like that, you know, but can it be done? Well, with risk, a lot of people told us we couldn't do it. But after a period of time, we were able to develop secure funding for, after competition, this instrument, and it was heretical. From a spacecraft in orbit around another planet, firing pulses of laser light and measuring the distance, round-trip travel time of a pulse of light to a billionth of a second, in the context of that moving spacecraft and a spinning planet around the sun, moving at kilometers per second, all around, all that stuff, putting it together and making a map of another world. Well, we did so. But what I remember most, aside from launching it, which was great, it ended up flying on a spacecraft about the size of a refrigerator called the Mars Global Surveyor, little old MGS. Sounds like something from a Chinese restaurant. But no, it was a spacecraft. Anyway, we got it to Mars in the fall of 1997. And we had a period of a couple of weeks before we had to do other work where we could try out our experiment. And I remember first light, we opened up the laser instrument, which has a telescope and a system that fires laser pulses, and we turned it on. And a few hours later, there's this packet of information back from Mars. Now, we looked at it, and all of a sudden we realized fundamental stuff. From the first little profile of Mars at this exquisite new scale, we saw how flat the landscape was in some places. For tens of miles, absolutely flat, not varying by more than a foot. That tells us something about how that landscape was, probably resulting from interaction of water making things flat as they do on Earth. We also flew over and measured the shape of a big volcanic center, like Hawaii. Only on Mars this one was called Elysium, and we saw the shapes of volcanoes. And very soon, my part of that experiment was measuring the shapes of landforms made by collision, impact landforms, craters. Lots of them on Mars and the moon, not so many on Earth. We got a cross section of this beautiful crater with all kinds of wild stuff that we hadn't expected, because we had never made the measurement before. So we were all pulling our hair off, celebrating, jumping up and down, and it was amazing. I need to just put that in context. A year and a half before, we flew a similar instrument, my experiment in this case, in the space shuttle, called the Shuttle Laser Altimeter, or SLA. Again, very originally named. I admit we could use some work there. Please help us. But anyway, we turned on our instrument on the space shuttle. We launched it from Florida. We were all here at the Goddard Space Flight Center amidst a major blizzard. 30-odd inches of snow was difficult even to get here. But we were there. We turned the laser on, had a crew. Everything's great in the shuttle endeavor, and the crew went to sleep because our laser was firing and it was not totally eye-safe. Anyway, we turned it on and the first day is coming back. Now Mars is a long way away, Earth orbit isn't, so it was coming back in real time. We're there looking at it with our team of scientists and engineers, great group of women and men. We're looking at it, it looks, you know, pretty ordinary, and then all of a sudden there's this huge bump and it comes down. And one of the engineers says, oh crap, the thing didn't work. Something's wrong. We can't figure it out. And one of my friends says, Jim, what's out in the middle of the Pacific Ocean? I said, oh, I don't know Hawaii. I don't know a lot of stuff. I mean, it's a big place. They said, our coordinates here look pretty good. We flew right over the biggest volcano on planet Earth, Monacaia. And we went up the side of the volcano, went down the other side, and there was an excursion of 4,000 meters of relief. We measured it absolutely perfectly. We realized, holy crap, this thing really works. And by doing a little work, we were able to tell the people on the space shuttle, with our instrument and a few other things, the orbit of the shuttle was good too, about a foot. Now, they actually don't even need to know that. But we needed to to make our data right. And the crew were very impressed. Wow, we didn't want to orbit this foot. It's usually good to a few thousand. We're good to a foot. Well, we needed that. But anyway, that mission got us ready for the big experiment at Mars, which from the late 90s into the early 2000s, mapped the whole planet and allowed us to land the rovers that we've now been landing, precisely because we know where the ground is, and to find the good places to go and to start to unravel the landscape history of Mars. So for me, that first light, those first pulses, talking to our experiment in Mars orbit and in Earth orbit, were just, you know, they were breakthrough moments in my scientific career that I'll never forget. I mean, they were the Eureka Yahoo moments.