WEBVTT

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Today, I am going to talk to you about 
limits with a question mark.

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Are there limits?

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I am going to use two examples.

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One is the orbiting and landing 
of an asteroid with NEAR spacecraft.

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NEAR stands for 
Near-Earth-Asteroid-Rendezvous.

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And the other is exiting 
the solar system with Voyager.

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This is the kind of thing

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that is very much in line with 
the theme of Uncharted Waters,

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which, of course, is the theme 
of this conference.

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You know that we don't know 
a lot about asteroids,

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and we certainly did not 
fifteen years ago.

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We didn't know 
if they were a solid body

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or a rubble pile, a bunch of rocks.

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Are they moving together in space?

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So the idea is to leave Earth
and go and orbit an asteroid

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which is typically not spherical, by the way.

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And nobody had orbited 
a non-spherical body.

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So, asteroids, there are lot of them

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that go orbiting in the vicinity of Earth.

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As you can see here is the orbit of Mars

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and here is the orbit of Earth,

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and these are a few of the asteroids

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that cross the path of Earth.

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And, of course, we have been lucky

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that we haven't had too many collisions.

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There have been collisions
as I am sure you have heard.

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So the idea is to go to one of these,

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orbit it and study it 
for a long period of time.

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To do that you need the spacecraft.

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We started the work two months 
before this picture was taken.

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You see the spacecraft on top
of what we called a shake-table.

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Which means that we take 
the spacecraft, once it is finished,

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and then we vibrate it to a level

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which it is going to experience

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as it goes up on top of the rocket,

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through the atmosphere 
and then into space.

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And it better survive that, 
otherwise it will not work.

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So, that's what we did.

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The spacecraft and we moved 
on to Cape Canaveral.

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We put it on top of the rocket, 
as you can see here,

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and you can also see 
there is a protective shell

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which is called the heat-seal

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simply because it protects 
the spacecraft

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as the rocket moves through 
the atmosphere at a very high rate.

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(Buzzing sound)

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This is sort of my last walk

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through the tower 
that surrounds the rocket.

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By the way, the young lady that you see
is the first program manager

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that I appointed 
to a NASA planetary mission.

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And I am very proud 
of having worked with ladies

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who really know how to do it.

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(Applause)

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So this is the rocket and 
you can see the exhaust,

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it's a little bigger 
than your car exhaust.

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These are just the solid rockets

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that surround 
the main body of the rocket.

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And then, of course, when 
the fuel is exhausted from these,

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they fall off and then we go on
to the next main tank of the rocket

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and it goes up.

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This lasted a long time

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so I am not going to tell you a lot more
and spend time on it.

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Finally we launched on February of 1996.

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What you see in this ...

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This is Eros, this is the asteroid.

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We put the spacecraft around it into orbit,

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and it rotated every 
about 6 1/2 hours, or so.

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So the spacecraft is rotating

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and watches the asteroid 
as it rotates around.

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Getting there, of course, 
wasn't simple.

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So we launched and then we went

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by the asteroid Mathilde in 1997.

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We came back to Earth 
to change the plane of the orbit

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so that we could match 
the trajectory of the asteroid.

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And then, something happened

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just before we were 
ready to get into orbit.

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That is, we fired the onboard rocket

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and we lost the spacecraft.

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No communication
for almost 24 hours.

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It's the worst thing.

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It can ruin your whole day
when you are in this business.

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(Laughter)

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But fortunately we had built 
enough redundancy into the system

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that 24 hours later 
we got a weak signal

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and we got the control 
of the spacecraft again.

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We found out what happened,

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and it turned out that the two computers 
on board had a disagreement.

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The spacecraft computers couldn't 
agree with propulsion in engine computer

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and we got in trouble.

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We lost some fuel.

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We went around the Sun once more 
and finally we got into orbit.

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As we were approaching Eros, the asteroid,

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on February 12, two days 
before Valentine's day, mind you.

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Here was the picture,

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it looked like a heart.

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Of course we knew 
it was an optical illusion

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and, of course, 
we never published the picture

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because we would get 
into all kind of trouble.

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And when we got close, 
as you will see,

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what happened is that 
you had these three craters

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that were arranged in a triangle,

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and they looked with 
a kind of Sun angle and the shade,

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it looked like a heart from a distance.

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So, that is the kind of stuff 
that you see in the tabloids

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that in the United States 
we pick out in supermarkets.

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Supermarket counters.

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You know ... "Heart on Eros" ...

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So much for that.

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It was big news that a NASA spacecraft 
orbited an asteroid on February 12.

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CNN is very loud everywhere it goes,

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including the United States.

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(CNN Speaker): A close encounter

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between a NASA satellite and an asteroid.

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An unmanned spacecraft is now 
in orbit around an asteroid.

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It's supposed to teach us 
about these giant rocks,

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and perhaps help scientists to figure out

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how to protect us from a possible collision.

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That is our Trajectory Manager

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who was making, he and his team, 
most of the calculation.

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(CNN Video)

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And this is the Senator of Maryland.

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And now I am showing you 
the next episode,

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after we were in orbit for a year.

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We had charted the entire asteroid.

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We were familiar 
with every little corner

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and every little crater.

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And we just had a little bit of fuel left.

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And we said, "What are 
we going to do now?"

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Because to maintain a spacecraft
in orbit around an asteroid

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that has this kind of shape, 
like a potato,

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it's very hard and you have 
to really keep pushing

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and adjusting the orbit by using fuel.

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And we were at the end of the fuel.

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So what would happen is that 
the spacecraft would drift away.

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So what we did is, I went to NASA

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and persuaded the administrator that

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we were going to try to easy down
on the surface of the asteroid.

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He eventually agreed to let us do it.

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So the day came, again it was 
as I mentioned the year later.

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We had already calculated what 
the trajectory was going to be like.

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What you see here is 
the calculated trajectory,

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[it] is the black line.

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And the points are the real-time data.

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We had the laser altimeter 
that measured

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the distance of the spacecraft 
from the ground

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by signing a laser, 
getting the reflection

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and measuring the distance with 
the precision of about a centimeter.

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So we knew what was happening.

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And we figured that it would take about 
45 minutes to get down to the ground.

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It seemed like it was going very well.

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I will show you a simulation
of what we had done

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with the spacecraft as you see it.

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And in fact, the spacecraft landed

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with the solar panels pointing 
in the direction of the Sun,

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with the antenna pointing 
in the direction of Earth,

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and we kept getting data.

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And it went on for a number of days.

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What you see is the pictures 
that were taken by the spacecraft

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as it was moving into closer 
and closer to the surface of Eros.

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And at the end we had a resolution
which was actually quite good.

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You can see here, 
this is the last image we had.

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You can discriminate and see rocks

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that were of the order 
of a few centimeters across.

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Well, that wasn't all.

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We had the opportunity 
to do other things.

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This is the announcement 
that we had actually landed.

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And Mr.Goldin, who was 
the NASA administrator at the time,

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was exceptionally anxious because

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NASA had just crashed 
a spacecraft on Mars a month before.

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And he was very worried about 
what was going to happen,

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if this happened again, 
to NASA's reputation.

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But he was very happy.

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Then, I wanted to show you 
another thing, here,

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about the details of the surface.

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There is a crater

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that the International Astronomical Union

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in its wisdom decided to name Hios,

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which was the love child of 
Poseidon and the nymph Hiona.

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So we have a crater on Eros 
by the name of Hios.

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Nothing to do with the fact 
that I am from Chios, mind you.

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(Laughter)

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The most important thing, however, 
is that we finished the project

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and we didn't spend all the money.

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Which had never happened 
in the history of NASA.

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We had a little ceremony,

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the down payment to NASA of
the remainder of 3.6 million dollars.

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In the end we gave them 
back about 30 million.

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Needless to say, we got a lot of abuse
from my other colleagues at NASA centers

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who said, "You never give back 
money to the government.

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"Shame on you", and so and so .

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But we overcame.

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Now let me tell you about the other part

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of the things that go 
on uncharted waters.

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What you see here is 
a view of the solar system.

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Each one of our planets 
of the solar system

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has already been imaged by spacecrafts.

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The four planets you see here,

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Jupiter, Saturn, Uranus, Neptune

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are all, of course, pictures 
from the Voyager mission.

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The Voyager mission started 
in 1977, ladies and gentlemen.

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It was 36 years ago, 
in a couple of months.

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The original plan was to go 
to Jupiter and to Saturn.

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It was going to be a four year mission.

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But then it turned out that it was possible

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using gravity assist 
from Jupiter to go on to Saturn,

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but then also using gravity assist

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from Saturn to go on to Uranus

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and from Uranus to Neptune.

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And that's exactly what 
we did with Voyager 2

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while we sent Voyager 1 
away from the Sun

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and towards the north ecliptic.

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That was a very well planned program,

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it worked well, it provided 
essentially all new information.

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And I just want to show you

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the spacecraft which 
is about this size.

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This is the antenna,
it points in the direction of Earth.

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It transmits information.

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These here is the instrument 
from my team.

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And I am pointing it out loud

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because it did some other things 
that we were very proud of.

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I am showing you this picture

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with President Herbert Walker Bush.

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Not the new one,
not the son, the father.

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He had a lot of brains, the father.

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(Laughter)

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He invited us to the White House

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as had done Mr. Reagan before him.

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And I am showing you 
that simply because

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to point out that the American 
government, the politicians,

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really appreciate what science 
does for the country.

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And it is not just NASA,

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it's the National Institute of Health,

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it's all kind of national science foundations.

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And they show it. Effectively.

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With this kind of things,

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by inviting us to lunch, 
and things like that.

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Anyway. This, after Voyager went 
past all these four planets.

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This is a simulation, 
that I am showing you,

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where it was moving away 
from the Sun

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passed the last planet, 
the orbit of Pluto.

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And we expected that someday

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we were going to run into this boundary

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and then eventually 
cross another boundary

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that would lead us into the galaxy.

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The problem was that nobody knew
how far these boundaries were.

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We were sort of going in blind.

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There were suggestions that it could be

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a year away, five years away,
ten years away.

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Nobody really knew.

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So, how to find it out?

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We had four instruments 
that were working.

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This is the one that I pointed out 
before, our team had built.

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And another thing that we did

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is to put a little stepper motor

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that rotated the entire platform 
back and forth.

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I'll show you a very short video.

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(Buzzing sound)

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That is the kind of sound it made 
in the laboratory, when it rotated.

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I did this little video for the press

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right after the Neptune encounter.

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I did have hair at one time, you noticed? 
(Laughter).

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We had this little stepper motor

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that was rotating the detectors.

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Just like this simulation shows.

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And you see the colors here.

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You can't see them 
because of these lights.

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But by rotating around 
it was possible for us

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to measure the speed and the direction 
of the hot wind from the Sun,

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which moves at the speed of about
1.5 million Km per hour.

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Now, you say, "OK, you told us 
about these instruments,

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what did you find by rotating this?"

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What we found...

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Here it is, we kept going 
and going and going.

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The idea was that once 
we cross this boundary

00:17:02.685 --> 00:17:04.692
we would be out in the galaxy.

00:17:04.692 --> 00:17:08.715
What we found instead
is that we ran into a place

00:17:08.715 --> 00:17:14.058
where the solar wind no longer
moved away from the Sun.

00:17:14.058 --> 00:17:18.206
And we called that 
the Stagnation Region.

00:17:18.206 --> 00:17:21.838
We published it in 2011.

00:17:21.838 --> 00:17:24.683
It was not predicted by theory.

00:17:24.683 --> 00:17:30.016
However some models were suggesting 
that what happens to this wind

00:17:30.024 --> 00:17:34.849
is that it goes to the north direction
towards the ecliptic pole.

00:17:34.914 --> 00:17:38.879
Our instrument, however, 
was only rotating in one plane

00:17:38.879 --> 00:17:42.271
and we couldn't measure 
the speed up and down.

00:17:42.271 --> 00:17:45.703
So, I asked the engineering team,

00:17:45.703 --> 00:17:50.900
I said "Why don't we turn the spacecraft 
90 degrees, now and then?

00:17:50.900 --> 00:17:53.685
And then we can measure 
the north-south direction."

00:17:53.685 --> 00:17:56.251
Mind you, this is a spacecraft

00:17:56.251 --> 00:18:01.162
that had been in space 
for 34 years already.

00:18:01.162 --> 00:18:05.085
And it is just like getting 
a dog that's about to die

00:18:05.085 --> 00:18:07.385
trying to teach him new tricks.

00:18:07.385 --> 00:18:09.680
However, what happened is

00:18:09.680 --> 00:18:13.330
that we were able 
to send the commands,

00:18:13.330 --> 00:18:14.918
and by guiding the spacecraft

00:18:14.918 --> 00:18:18.097
it executed every command perfectly.

00:18:18.097 --> 00:18:21.835
And for two years we have been 
doing this every two months.

00:18:21.835 --> 00:18:24.686
We rotated the spacecraft 
in this direction.

00:18:24.686 --> 00:18:28.223
What we found out is that, in fact,

00:18:28.223 --> 00:18:30.456
even this model was also wrong.

00:18:30.456 --> 00:18:34.021
There was no flow of the wind 
in the north direction

00:18:34.021 --> 00:18:36.086
or in the south direction 
for that matter.

00:18:36.086 --> 00:18:39.381
So theory failed us again.

00:18:40.420 --> 00:18:44.868
We actually wrote this up
and were publishing it

00:18:44.868 --> 00:18:50.838
until we found something very strange
that happened last year.

00:18:50.838 --> 00:18:53.495
What you see here,

00:18:53.495 --> 00:18:56.936
and it is the only data that I will show you,

00:18:56.936 --> 00:19:01.704
is the curve for cosmic rays, the intensity.

00:19:01.704 --> 00:19:09.973
And you see that they started increasing
right about early May of 2012.

00:19:10.009 --> 00:19:12.826
These are the so-called 
Galactic Cosmic Rays.

00:19:12.826 --> 00:19:18.678
These are particles that were actually 
generated by explosions of Supernovae

00:19:18.678 --> 00:19:21.895
millions of years ago
in the vicinity of the Sun,

00:19:21.895 --> 00:19:25.939
and were coming from outside 
the galaxy into our solar system.

00:19:25.939 --> 00:19:28.124
And they began to go up.

00:19:28.124 --> 00:19:32.923
And then, eventually, 
at about the same time,

00:19:32.923 --> 00:19:35.711
after two or three increases,

00:19:35.711 --> 00:19:38.869
the material that was coming from the Sun,

00:19:38.869 --> 00:19:43.419
never mind what these are, protons and 
heliums and what we have here, oxygen  

00:19:43.419 --> 00:19:45.146
dropped at the same time.

00:19:45.146 --> 00:19:48.292
In other words, 
the solar material disappears

00:19:48.292 --> 00:19:50.547
and the stuff that was supposed to be coming

00:19:50.547 --> 00:19:52.927
from outside the galaxy 
-- that's what we believed --

00:19:52.927 --> 00:19:55.794
appeared and increased.

00:19:55.794 --> 00:20:01.960
So we said, "Aha! We actually got out of 
the solar system and into the galaxy!"

00:20:02.016 --> 00:20:03.888
But we lacked some data.

00:20:03.888 --> 00:20:06.564
This is a picture from a press event

00:20:06.564 --> 00:20:10.225
at the Jet Propulsion 
Laboratory in Pasadena.

00:20:10.225 --> 00:20:13.270
We were trying to interpret the data

00:20:13.270 --> 00:20:16.756
a few days after 
we had made that observation.

00:20:16.756 --> 00:20:20.086
Here we have the model 
of the spacecraft.

00:20:20.086 --> 00:20:23.532
But we didn't have 
all the data that we needed.

00:20:23.532 --> 00:20:28.282
Namely, we couldn't measure the density
of the atmosphere of the galaxy,

00:20:28.282 --> 00:20:30.471
if I can put it that way.

00:20:30.471 --> 00:20:35.142
Until April of this year.

00:20:35.142 --> 00:20:36.687
I don't know if you can hear the sound,

00:20:36.687 --> 00:20:39.882
maybe you can turn it up a little bit?

00:20:39.882 --> 00:20:41.295
(Whistling sound)

00:20:41.295 --> 00:20:44.747
OK. Now, what are these,

00:20:44.747 --> 00:20:49.008
is, we have some antennas on the spacecraft.

00:20:49.008 --> 00:20:52.661
And in the vicinity of the spacecraft
something happened

00:20:52.661 --> 00:20:56.011
and all these electrons 
began to oscillate back and forth.

00:20:56.011 --> 00:20:57.956
When the electrons oscillate 
in a magnetic field

00:20:57.956 --> 00:20:59.792
they produce sounds.

00:20:59.792 --> 00:21:02.358
And when they produce this sound

00:21:02.358 --> 00:21:07.086
we are able to determine 
the density of the material

00:21:07.086 --> 00:21:08.480
around the spacecraft.

00:21:08.480 --> 00:21:13.423
What you see here is that 
we were able to determine

00:21:13.423 --> 00:21:17.767
that it was 0.1 per cubic centimeter.

00:21:17.767 --> 00:21:19.347
You would say, 
"What does that mean?"

00:21:19.347 --> 00:21:24.049
Well, it was 50 times 
what we had before.

00:21:24.049 --> 00:21:28.776
When we were in the solar wind,
inside our solar atmosphere.

00:21:28.785 --> 00:21:31.567
And because most models predict

00:21:31.567 --> 00:21:35.330
that the density in the galaxy is about 0.1,

00:21:35.330 --> 00:21:38.865
we knew that we had actually arrived.

00:21:38.865 --> 00:21:46.449
So, we had a meeting at my lab
back in Johns Hopkins in September.

00:21:46.524 --> 00:21:50.089
We looked at all the data 
and we finally decided

00:21:50.089 --> 00:21:53.588
that it was safe 
to issue a press release

00:21:53.588 --> 00:21:59.128
that actually we had crossed

00:21:59.128 --> 00:22:05.687
the boundary with the galaxy
on August 25 of 2012.

00:22:05.687 --> 00:22:09.100
So, think about this:

00:22:09.101 --> 00:22:11.785
a hundred and ten years ago,

00:22:11.785 --> 00:22:14.880
it was when the Wright brothers

00:22:14.880 --> 00:22:19.068
flew a... you could call it an airplane

00:22:19.068 --> 00:22:21.881
-- that's what they called it --

00:22:21.881 --> 00:22:25.221
at an altitude of few meters
for about 30 seconds.

00:22:25.221 --> 00:22:28.664
And then about 50 years later

00:22:28.664 --> 00:22:33.527
there was the launch 
of the first Earth satellite, Sputnik.

00:22:33.527 --> 00:22:38.423
It went outside the Earth's 
atmosphere for the first time ever

00:22:38.423 --> 00:22:42.189
in our history, in humanity's history.

00:22:42.189 --> 00:22:49.114
And it got to an altitude 
of 946 km, to be exact.

00:22:49.114 --> 00:22:54.932
And then another 55, or so, years later,

00:22:54.932 --> 00:22:58.731
we had the exit of the first 
spacecraft, Voyager 1

00:22:58.731 --> 00:23:07.604
from the atmosphere of the Sun
at an altitude of 18.2 billion kilometers.

00:23:07.604 --> 00:23:09.479
To give you an idea:

00:23:09.479 --> 00:23:12.191
the signal that we get from Voyager,

00:23:12.191 --> 00:23:15.130
when it leaves Voyager, 
it travels with the speed of light,

00:23:15.130 --> 00:23:20.148
and it takes 17 hours and 20 minutes
to get from there to Earth.

00:23:20.148 --> 00:23:24.313
The light from the Sun to come to Earth
only takes 8 1/2 minutes.

00:23:24.313 --> 00:23:27.547
So you can imagine 
how far this spacecraft is.

00:23:27.550 --> 00:23:31.986
To give you the bottom line, so to speak.

00:23:31.986 --> 00:23:35.025
Here we are. 
Voyager 1 is in the galaxy.

00:23:35.025 --> 00:23:38.212
Voyager 2 is not there yet, 
it is a little slower,

00:23:38.212 --> 00:23:42.080
so we expect it will go out at some point.

00:23:43.590 --> 00:23:48.088
Finally, I can imagine that 
there was a rooster there

00:23:48.088 --> 00:23:50.701
that said "People of Earth, 
welcome to the galaxy!",

00:23:50.701 --> 00:23:52.384
(Laughter)

00:23:52.384 --> 00:23:55.147
on August 25, 2012.

00:23:56.387 --> 00:24:01.047
I posed the question in the beginning: 
"Are there limits?"

00:24:01.234 --> 00:24:06.902
I think you can imagine that my answer 
to that is "No, of course no."

00:24:06.902 --> 00:24:12.314
I think limits constrain our imagination

00:24:12.314 --> 00:24:16.093
and retard progress, I think.

00:24:16.101 --> 00:24:20.263
So, we don't need any limits.

00:24:20.263 --> 00:24:21.551
And there are none.

00:24:21.554 --> 00:24:23.134
Thank you very much.

00:24:23.134 --> 00:24:31.761
(Applause)