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