Chapter 1: The Laser Is Better
Narration: Lauren Ward
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The laser: a useful tool
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in industry, science and medicine.
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When it comes down to it, a laser is just a light with extreme focus.
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It's both elegantly simple and extremely complicated,
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and it changed the way we literally see the dimensions of our Earth,
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our Moon, the planets, asteroids and beyond.
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But it was a long road to get there.
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Back in the 1980s at NASA, using lasers to measure
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physical features from space was too experimental, too risky.
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Fortunately, it was also a time of change and risk
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taking at Goddard Space Flight Center.
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In the 1960s, there was probably not much question
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when a science or applications mission came up.
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For the most part, it went to Goddard
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and we we've got to do a better job of selling ourselves
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and being sure that we're responsive to what headquarters is looking for
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in terms of the competition between ourselves and other NASA centers.
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I came here as a hired by the center director,
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Noel Hinners in '85, and he said, So what do you want to do?
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I said, I want to map the topography of Mars, you know, at this scale, not
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the scale of buildings.
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How do we do that?
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He goes, Well, we've got folks. They do stuff.
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And so I met a few of them very quickly, and that was Jim Abshire, John
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Degnan, Jack Bufton.
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We started working with laser remote sensing instrumentation.
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It was the same type of instrumentation that communicated
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from ground to satellites and satellite laser ranging.
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We could do a little airborne laser remote
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sensing, and Garvin and I sort of found each other through that.
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You know, I said, Come on down to Wallops and we'll fly this.
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And he said, Oh, topography, Earth, yes, I want to measure it.
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We literally took a T-39 training aircraft that was
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put together by the Wallops Team really impressively
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and bolted in a big telescope with a laser
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and went flying out in northern Arizona where I had done some field work.
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So out there we have Meteor Crater, we have volcanoes
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and we have the Grand Canyon and other the Painted Desert.
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So we figured in one place we could study all this.
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And it was on the strength of that, that the Jim Garvin became interested
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and put him in a position to when Dave Smith found
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that his radar altimeter was canceled because it was $30 million instead of ten.
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They kept talking to me about, you know,
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look, we're really close to getting a laser altimeter working.
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And I've been in lasers actually for 20 odd years before that,
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if you know what I mean.
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But laser ranging from the ground to spacecraft.
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So I was very familiar with the lasers and I wasn't averse to it, on the contrary.
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But NASA offered me a situation that said, look,
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we've got a certain amount of money for you
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willing to spend $10 million on this instrument.
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But, you know, there has to be some sort of competition.
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You need to choose which instrument
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you would like to fly to measure the altimetry.
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And there were four candidates.
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Three of them are
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radar and one the laser that we call MOLA
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There was no one in their right mind that would bid
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a laser altimeter seriously.
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And I was all gung ho.
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I was a young guy, you know, no gray hair.
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There was a lot of reticence.
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There was so little trust that this could be done.
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NASA's made a monumental achievement
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in both radar, radar and visible near infrared
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imaging of the surfaces of Earth and other planets.
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But those are flat field views.
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And the missing dimension,
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the hidden dimension, which drives where energy goes, where the water flows,
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stability of landscapes is the third dimension we take for granted the map.
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Sometimes you need the map to do with beyond the map.
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Making those maps with that crucial third dimension is
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what laser altimetry or LiDAR is best at.
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And over the decades
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Goddard's gotten pretty good at explaining just how laser altimetry works.
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This is a laser altimeter.
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What it does is it sends a short pulse of light.
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From a moving platform that's observing a surface, an airplane, a satellite.
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Gets a reflection straight back off the surface.
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We record that reflection and the time very precisely.
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Of the pulse from the spacecraft down to the surface and back again.
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Which allows us to measure the range to the surface.
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When that's done repeatedly in orbit, you can build up a map.
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The fast rate of
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light pulses and the small footprint allow lidar
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to measure with a much finer scale than traditional radars.
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They had a big review and the leading radar guy
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that had flown radars to Venus, Gordon Pettengil, at the end said, well,
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I don't know about you folks, the laser is better.
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In time, Goddard would become a leader in lidar
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in mapping our earth and planets with unprecedented precision.
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But for now, they had to actually build the first one.
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The requirements were, of course, we were at a much higher orbit,
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and orbit was faster than going around the Moon So we needed a larger telescope,
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needed a more sensitive detector, we needed more laser energy.
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So in order to put our concept together, we had to gather a team
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and then we
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had to convince the management that this was not a crazy idea
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and that we actually had a realistic chance of making this happen.
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We worked a lot of hours.
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I can remember
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Jim talking about, you know, working ten hour days and I was doing about the same.
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But, you know, it really it really didn't matter
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because it was so exciting
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to to be working on something that was going to actually map Mars.
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I was fresh out of getting my master's degree in computer engineering.
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I was young.
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I mean, I was it was I had to really dive in deep.
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I had to spend about two years working with the team on algorithms.
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How were we going to find the surface of the of Mars, how we were going
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to track it, how we're going to compute all the precise ranges.
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And we were just we were sort of making our way.
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We were we were defining the rules as we went.
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We finished the instrument pretty much on time.
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And certainly, as they said in the letter to me, look,
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if you don't make it on time and in budget, we will fly a brick instead.
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Okay? We're not going to hold this mission up.
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I mean, I knew about planetary missions.
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They have to go within certain windows.
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But anyway, we made it alright.
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Five, four, three, two, one.
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Liftoff of the Titan.
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Three rocket with the Mars Observer and America's return to the Red Planet.
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And the vehicle has cleared the tower.
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We've got X-band launch at Canberra.
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A very happy crew.
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The Mars Observer is on the way to Mars.
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Trajectory is right on the money.
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that the spacecraft properly executed its orbit insertion sequence,
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and we presume the spacecraft is in orbit about Mars.
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But we have no positive confirmation of that because as for the last three days,
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we have no communication with the spacecraft.
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--That is to say you simply don't know what happened to that.
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It could be in orbit. It could have flown past the planet.
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What are the scientists doing to relieve the tension in there?
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Screaming loudly, probably.
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We still don't have communication with the spacecraft.
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However, we are very hopeful and we're cautiously optimistic
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that communication-- --Every day we restore without communications
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clearly lessons our probability of success.
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--Though, you know, we give up?
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We have not given up.
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You know but I was not concerned about the spacecraft.
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It never crossed my mind. The spacecraft would let us down.
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So this was a blow in the sense of, wow,
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something I completely didn't expect.