Today, I am going to talk to you about limits with a question mark.
Are there limits?
I am going to use two examples.
One is the orbiting and landing of an asteroid with NEAR spacecraft.
NEAR stands for Near-Earth-Asteroid-Rendezvous.
And the other is exiting the solar system with Voyager.
This is the kind of thing
that is very much in line with the theme of Uncharted Waters,
which, of course, is the theme of this conference.
You know that we don't know a lot about asteroids,
and we certainly did not fifteen years ago.
We didn't know if they were a solid body
or a rubble pile, a bunch of rocks.
Are they moving together in space?
So the idea is to leave Earth and go and orbit an asteroid
which is typically not spherical, by the way.
And nobody had orbited a non-spherical body.
So, asteroids, there are lot of them
that go orbiting in the vicinity of Earth.
As you can see here is the orbit of Mars
and here is the orbit of Earth,
and these are a few of the asteroids
that cross the path of Earth.
And, of course, we have been lucky
that we haven't had too many collisions.
There have been collisions as I am sure you have heard.
So the idea is to go to one of these,
orbit it and study it for a long period of time.
To do that you need the spacecraft.
We started the work two months before this picture was taken.
You see the spacecraft on top of what we called a shake-table.
Which means that we take the spacecraft, once it is finished,
and then we vibrate it to a level
which it is going to experience
as it goes up on top of the rocket,
through the atmosphere and then into space.
And it better survive that, otherwise it will not work.
So, that's what we did.
The spacecraft and we moved on to Cape Canaveral.
We put it on top of the rocket, as you can see here,
and you can also see there is a protective shell
which is called the heat-seal
simply because it protects the spacecraft
as the rocket moves through the atmosphere at a very high rate.
(Buzzing sound)
This is sort of my last walk
through the tower that surrounds the rocket.
By the way, the young lady that you see is the first program manager
that I appointed to a NASA planetary mission.
And I am very proud of having worked with ladies
who really know how to do it.
(Applause)
So this is the rocket and you can see the exhaust,
it's a little bigger than your car exhaust.
These are just the solid rockets
that surround the main body of the rocket.
And then, of course, when the fuel is exhausted from these,
they fall off and then we go on to the next main tank of the rocket
and it goes up.
This lasted a long time
so I am not going to tell you a lot more and spend time on it.
Finally we launched on February of 1996.
What you see in this ...
This is Eros, this is the asteroid.
We put the spacecraft around it into orbit,
and it rotated every about 6 1/2 hours, or so.
So the spacecraft is rotating
and watches the asteroid as it rotates around.
Getting there, of course, wasn't simple.
So we launched and then we went
by the asteroid Mathilde in 1997.
We came back to Earth to change the plane of the orbit
so that we could match the trajectory of the asteroid.
And then, something happened
just before we were ready to get into orbit.
That is, we fired the onboard rocket
and we lost the spacecraft.
No communication for almost 24 hours.
It's the worst thing.
It can ruin your whole day when you are in this business.
(Laughter)
But fortunately we had built enough redundancy into the system
that 24 hours later we got a weak signal
and we got the control of the spacecraft again.
We found out what happened,
and it turned out that the two computers on board had a disagreement.
The spacecraft computers couldn't agree with propulsion in engine computer
and we got in trouble.
We lost some fuel.
We went around the Sun once more and finally we got into orbit.
As we were approaching Eros, the asteroid,
on February 12, two days before Valentine's day, mind you.
Here was the picture,
it looked like a heart.
Of course we knew it was an optical illusion
and, of course, we never published the picture
because we would get into all kind of trouble.
And when we got close, as you will see,
what happened is that you had these three craters
that were arranged in a triangle,
and they looked with a kind of Sun angle and the shade,
it looked like a heart from a distance.
So, that is the kind of stuff that you see in the tabloids
that in the United States we pick out in supermarkets.
Supermarket counters.
You know ... "Heart on Eros" ...
So much for that.
It was big news that a NASA spacecraft orbited an asteroid on February 12.
CNN is very loud everywhere it goes,
including the United States.
(CNN Speaker): A close encounter
between a NASA satellite and an asteroid.
An unmanned spacecraft is now in orbit around an asteroid.
It's supposed to teach us about these giant rocks,
and perhaps help scientists to figure out
how to protect us from a possible collision.
That is our Trajectory Manager
who was making, he and his team, most of the calculation.
(CNN Video)
And this is the Senator of Maryland.
And now I am showing you the next episode,
after we were in orbit for a year.
We had charted the entire asteroid.
We were familiar with every little corner
and every little crater.
And we just had a little bit of fuel left.
And we said, "What are we going to do now?"
Because to maintain a spacecraft in orbit around an asteroid
that has this kind of shape, like a potato,
it's very hard and you have to really keep pushing
and adjusting the orbit by using fuel.
And we were at the end of the fuel.
So what would happen is that the spacecraft would drift away.
So what we did is, I went to NASA
and persuaded the administrator that
we were going to try to easy down on the surface of the asteroid.
He eventually agreed to let us do it.
So the day came, again it was as I mentioned the year later.
We had already calculated what the trajectory was going to be like.
What you see here is the calculated trajectory,
[it] is the black line.
And the points are the real-time data.
We had the laser altimeter that measured
the distance of the spacecraft from the ground
by signing a laser, getting the reflection
and measuring the distance with the precision of about a centimeter.
So we knew what was happening.
And we figured that it would take about 45 minutes to get down to the ground.
It seemed like it was going very well.
I will show you a simulation of what we had done
with the spacecraft as you see it.
And in fact, the spacecraft landed
with the solar panels pointing in the direction of the Sun,
with the antenna pointing in the direction of Earth,
and we kept getting data.
And it went on for a number of days.
What you see is the pictures that were taken by the spacecraft
as it was moving into closer and closer to the surface of Eros.
And at the end we had a resolution which was actually quite good.
You can see here, this is the last image we had.
You can discriminate and see rocks
that were of the order of a few centimeters across.
Well, that wasn't all.
We had the opportunity to do other things.
This is the announcement that we had actually landed.
And Mr.Goldin, who was the NASA administrator at the time,
was exceptionally anxious because
NASA had just crashed a spacecraft on Mars a month before.
And he was very worried about what was going to happen,
if this happened again, to NASA's reputation.
But he was very happy.
Then, I wanted to show you another thing, here,
about the details of the surface.
There is a crater
that the International Astronomical Union
in its wisdom decided to name Hios,
which was the love child of Poseidon and the nymph Hiona.
So we have a crater on Eros by the name of Hios.
Nothing to do with the fact that I am from Chios, mind you.
(Laughter)
The most important thing, however, is that we finished the project
and we didn't spend all the money.
Which had never happened in the history of NASA.
We had a little ceremony,
the down payment to NASA of the remainder of 3.6 million dollars.
In the end we gave them back about 30 million.
Needless to say, we got a lot of abuse from my other colleagues at NASA centers
who said, "You never give back money to the government.
"Shame on you", and so and so .
But we overcame.
Now let me tell you about the other part
of the things that go on uncharted waters.
What you see here is a view of the solar system.
Each one of our planets of the solar system
has already been imaged by spacecrafts.
The four planets you see here,
Jupiter, Saturn, Uranus, Neptune
are all, of course, pictures from the Voyager mission.
The Voyager mission started in 1977, ladies and gentlemen.
It was 36 years ago, in a couple of months.
The original plan was to go to Jupiter and to Saturn.
It was going to be a four year mission.
But then it turned out that it was possible
using gravity assist from Jupiter to go on to Saturn,
but then also using gravity assist
from Saturn to go on to Uranus
and from Uranus to Neptune.
And that's exactly what we did with Voyager 2
while we sent Voyager 1 away from the Sun
and towards the north ecliptic.
That was a very well planned program,
it worked well, it provided essentially all new information.
And I just want to show you
the spacecraft which is about this size.
This is the antenna, it points in the direction of Earth.
It transmits information.
These here is the instrument from my team.
And I am pointing it out loud
because it did some other things that we were very proud of.
I am showing you this picture
with President Herbert Walker Bush.
Not the new one, not the son, the father.
He had a lot of brains, the father.
(Laughter)
He invited us to the White House
as had done Mr. Reagan before him.
And I am showing you that simply because
to point out that the American government, the politicians,
really appreciate what science does for the country.
And it is not just NASA,
it's the National Institute of Health,
it's all kind of national science foundations.
And they show it. Effectively.
With this kind of things,
by inviting us to lunch, and things like that.
Anyway. This, after Voyager went past all these four planets.
This is a simulation, that I am showing you,
where it was moving away from the Sun
passed the last planet, the orbit of Pluto.
And we expected that someday
we were going to run into this boundary
and then eventually cross another boundary
that would lead us into the galaxy.
The problem was that nobody knew how far these boundaries were.
We were sort of going in blind.
There were suggestions that it could be
a year away, five years away, ten years away.
Nobody really knew.
So, how to find it out?
We had four instruments that were working.
This is the one that I pointed out before, our team had built.
And another thing that we did
is to put a little stepper motor
that rotated the entire platform back and forth.
I'll show you a very short video.
(Buzzing sound)
That is the kind of sound it made in the laboratory, when it rotated.
I did this little video for the press
right after the Neptune encounter.
I did have hair at one time, you noticed? (Laughter).
We had this little stepper motor
that was rotating the detectors.
Just like this simulation shows.
And you see the colors here.
You can't see them because of these lights.
But by rotating around it was possible for us
to measure the speed and the direction of the hot wind from the Sun,
which moves at the speed of about 1.5 million Km per hour.
Now, you say, "OK, you told us about these instruments,
what did you find by rotating this?"
What we found...
Here it is, we kept going and going and going.
The idea was that once we cross this boundary
we would be out in the galaxy.
What we found instead is that we ran into a place
where the solar wind no longer moved away from the Sun.
And we called that the Stagnation Region.
We published it in 2011.
It was not predicted by theory.
However some models were suggesting that what happens to this wind
is that it goes to the north direction towards the ecliptic pole.
Our instrument, however, was only rotating in one plane
and we couldn't measure the speed up and down.
So, I asked the engineering team,
I said "Why don't we turn the spacecraft 90 degrees, now and then?
And then we can measure the north-south direction."
Mind you, this is a spacecraft
that had been in space for 34 years already.
And it is just like getting a dog that's about to die
trying to teach him new tricks.
However, what happened is
that we were able to send the commands,
and by guiding the spacecraft
it executed every command perfectly.
And for two years we have been doing this every two months.
We rotated the spacecraft in this direction.
What we found out is that, in fact,
even this model was also wrong.
There was no flow of the wind in the north direction
or in the south direction for that matter.
So theory failed us again.
We actually wrote this up and were publishing it
until we found something very strange that happened last year.
What you see here,
and it is the only data that I will show you,
is the curve for cosmic rays, the intensity.
And you see that they started increasing right about early May of 2012.
These are the so-called Galactic Cosmic Rays.
These are particles that were actually generated by explosions of Supernovae
millions of years ago in the vicinity of the Sun,
and were coming from outside the galaxy into our solar system.
And they began to go up.
And then, eventually, at about the same time,
after two or three increases,
the material that was coming from the Sun,
never mind what these are, protons and heliums and what we have here, oxygen
dropped at the same time.
In other words, the solar material disappears
and the stuff that was supposed to be coming
from outside the galaxy -- that's what we believed --
appeared and increased.
So we said, "Aha! We actually got out of the solar system and into the galaxy!"
But we lacked some data.
This is a picture from a press event
at the Jet Propulsion Laboratory in Pasadena.
We were trying to interpret the data
a few days after we had made that observation.
Here we have the model of the spacecraft.
But we didn't have all the data that we needed.
Namely, we couldn't measure the density of the atmosphere of the galaxy,
if I can put it that way.
Until April of this year.
I don't know if you can hear the sound,
maybe you can turn it up a little bit?
(Whistling sound)
OK. Now, what are these,
is, we have some antennas on the spacecraft.
And in the vicinity of the spacecraft something happened
and all these electrons began to oscillate back and forth.
When the electrons oscillate in a magnetic field
they produce sounds.
And when they produce this sound
we are able to determine the density of the material
around the spacecraft.
What you see here is that we were able to determine
that it was 0.1 per cubic centimeter.
You would say, "What does that mean?"
Well, it was 50 times what we had before.
When we were in the solar wind, inside our solar atmosphere.
And because most models predict
that the density in the galaxy is about 0.1,
we knew that we had actually arrived.
So, we had a meeting at my lab back in Johns Hopkins in September.
We looked at all the data and we finally decided
that it was safe to issue a press release
that actually we had crossed
the boundary with the galaxy on August 25 of 2012.
So, think about this:
a hundred and ten years ago,
it was when the Wright brothers
flew a... you could call it an airplane
-- that's what they called it --
at an altitude of few meters for about 30 seconds.
And then about 50 years later
there was the launch of the first Earth satellite, Sputnik.
It went outside the Earth's atmosphere for the first time ever
in our history, in humanity's history.
And it got to an altitude of 946 km, to be exact.
And then another 55, or so, years later,
we had the exit of the first spacecraft, Voyager 1
from the atmosphere of the Sun at an altitude of 18.2 billion kilometers.
To give you an idea:
the signal that we get from Voyager,
when it leaves Voyager, it travels with the speed of light,
and it takes 17 hours and 20 minutes to get from there to Earth.
The light from the Sun to come to Earth only takes 8 1/2 minutes.
So you can imagine how far this spacecraft is.
To give you the bottom line, so to speak.
Here we are. Voyager 1 is in the galaxy.
Voyager 2 is not there yet, it is a little slower,
so we expect it will go out at some point.
Finally, I can imagine that there was a rooster there
that said "People of Earth, welcome to the galaxy!",
(Laughter)
on August 25, 2012.
I posed the question in the beginning: "Are there limits?"
I think you can imagine that my answer to that is "No, of course no."
I think limits constrain our imagination
and retard progress, I think.
So, we don't need any limits.
And there are none.
Thank you very much.
(Applause)