0:00:09.545,0:00:16.297
Today, I am going to talk to you about [br]limits with a question mark.

0:00:16.297,0:00:17.771
Are there limits?

0:00:17.776,0:00:21.868
I am going to use two examples.

0:00:21.868,0:00:27.246
One is the orbiting and landing [br]of an asteroid with NEAR spacecraft.

0:00:27.246,0:00:31.063
NEAR stands for [br]Near-Earth-Asteroid-Rendezvous.

0:00:31.066,0:00:36.159
And the other is exiting [br]the solar system with Voyager.

0:00:37.009,0:00:38.776
This is the kind of thing

0:00:38.776,0:00:42.894
that is very much in line with [br]the theme of Uncharted Waters,

0:00:42.894,0:00:46.708
which, of course, is the theme [br]of this conference.

0:00:48.379,0:00:52.433
You know that we don't know [br]a lot about asteroids,

0:00:52.454,0:00:56.206
and we certainly did not [br]fifteen years ago.

0:00:56.206,0:00:59.735
We didn't know [br]if they were a solid body

0:00:59.735,0:01:02.045
or a rubble pile, a bunch of rocks.

0:01:02.045,0:01:04.616
Are they moving together in space?

0:01:04.616,0:01:08.429
So the idea is to leave Earth[br]and go and orbit an asteroid

0:01:11.719,0:01:13.888
which is typically not spherical, by the way.

0:01:13.888,0:01:17.256
And nobody had orbited [br]a non-spherical body.

0:01:18.465,0:01:24.764
So, asteroids, there are lot of them

0:01:24.764,0:01:28.149
that go orbiting in the vicinity of Earth.

0:01:28.149,0:01:31.219
As you can see here is the orbit of Mars

0:01:31.219,0:01:32.856
and here is the orbit of Earth,

0:01:32.856,0:01:36.100
and these are a few of the asteroids

0:01:36.120,0:01:38.913
that cross the path of Earth.

0:01:38.913,0:01:41.343
And, of course, we have been lucky

0:01:41.343,0:01:43.840
that we haven't had too many collisions.

0:01:43.840,0:01:47.165
There have been collisions[br]as I am sure you have heard.

0:01:47.165,0:01:50.275
So the idea is to go to one of these,

0:01:50.275,0:01:53.276
orbit it and study it [br]for a long period of time.

0:01:53.276,0:01:56.275
To do that you need the spacecraft.

0:01:56.275,0:02:03.000
We started the work two months [br]before this picture was taken.

0:02:03.000,0:02:08.287
You see the spacecraft on top[br]of what we called a shake-table.

0:02:08.293,0:02:12.845
Which means that we take [br]the spacecraft, once it is finished,

0:02:12.845,0:02:15.814
and then we vibrate it to a level

0:02:15.844,0:02:18.186
which it is going to experience

0:02:18.186,0:02:20.815
as it goes up on top of the rocket,

0:02:20.815,0:02:23.462
through the atmosphere [br]and then into space.

0:02:23.462,0:02:27.666
And it better survive that, [br]otherwise it will not work.

0:02:27.666,0:02:31.002
So, that's what we did.

0:02:31.112,0:02:34.551
The spacecraft and we moved [br]on to Cape Canaveral.

0:02:34.551,0:02:38.751
We put it on top of the rocket, [br]as you can see here,

0:02:38.751,0:02:44.245
and you can also see [br]there is a protective shell

0:02:44.245,0:02:47.176
which is called the heat-seal

0:02:47.176,0:02:50.440
simply because it protects [br]the spacecraft

0:02:50.440,0:02:54.714
as the rocket moves through [br]the atmosphere at a very high rate.

0:02:54.714,0:02:56.048
(Buzzing sound)

0:02:56.048,0:02:59.012
This is sort of my last walk

0:02:59.012,0:03:04.462
through the tower [br]that surrounds the rocket.

0:03:04.659,0:03:10.892
By the way, the young lady that you see[br]is the first program manager

0:03:10.892,0:03:14.390
that I appointed [br]to a NASA planetary mission.

0:03:14.425,0:03:21.119
And I am very proud [br]of having worked with ladies

0:03:21.119,0:03:25.632
who really know how to do it.

0:03:25.632,0:03:28.989
(Applause)

0:03:28.989,0:03:32.197
So this is the rocket and [br]you can see the exhaust,

0:03:32.197,0:03:35.231
it's a little bigger [br]than your car exhaust.

0:03:35.231,0:03:38.430
These are just the solid rockets

0:03:38.430,0:03:41.480
that surround [br]the main body of the rocket.

0:03:41.480,0:03:46.969
And then, of course, when [br]the fuel is exhausted from these,

0:03:46.969,0:03:53.074
they fall off and then we go on[br]to the next main tank of the rocket

0:03:53.074,0:03:54.363
and it goes up.

0:03:54.363,0:03:55.788
This lasted a long time

0:03:55.788,0:04:01.083
so I am not going to tell you a lot more[br]and spend time on it.

0:04:01.083,0:04:06.061
Finally we launched on February of 1996.

0:04:06.061,0:04:09.906
What you see in this ...

0:04:10.618,0:04:14.128
This is Eros, this is the asteroid.

0:04:14.128,0:04:17.689
We put the spacecraft around it into orbit,

0:04:17.689,0:04:23.037
and it rotated every [br]about 6 1/2 hours, or so.

0:04:23.087,0:04:25.234
So the spacecraft is rotating

0:04:25.234,0:04:28.010
and watches the asteroid [br]as it rotates around.

0:04:28.230,0:04:30.384
Getting there, of course, [br]wasn't simple.

0:04:30.384,0:04:35.020
So we launched and then we went

0:04:35.020,0:04:38.304
by the asteroid Mathilde in 1997.

0:04:38.304,0:04:42.371
We came back to Earth [br]to change the plane of the orbit

0:04:42.371,0:04:46.689
so that we could match [br]the trajectory of the asteroid.

0:04:46.799,0:04:52.341
And then, something happened

0:04:52.341,0:04:55.545
just before we were [br]ready to get into orbit.

0:04:55.545,0:04:58.317
That is, we fired the onboard rocket

0:04:58.317,0:05:00.942
and we lost the spacecraft.

0:05:00.972,0:05:06.980
No communication[br]for almost 24 hours.

0:05:06.980,0:05:08.841
It's the worst thing.

0:05:08.951,0:05:11.728
It can ruin your whole day[br]when you are in this business.

0:05:11.728,0:05:12.854
(Laughter)

0:05:12.854,0:05:17.375
But fortunately we had built [br]enough redundancy into the system

0:05:17.375,0:05:21.861
that 24 hours later [br]we got a weak signal

0:05:21.861,0:05:24.949
and we got the control [br]of the spacecraft again.

0:05:24.949,0:05:26.431
We found out what happened,

0:05:26.431,0:05:30.019
and it turned out that the two computers [br]on board had a disagreement.

0:05:30.019,0:05:35.131
The spacecraft computers couldn't [br]agree with propulsion in engine computer

0:05:35.131,0:05:37.196
and we got in trouble.

0:05:37.196,0:05:38.833
We lost some fuel.

0:05:38.833,0:05:46.129
We went around the Sun once more [br]and finally we got into orbit.

0:05:46.129,0:05:50.517
As we were approaching Eros, the asteroid,

0:05:50.517,0:05:55.245
on February 12, two days [br]before Valentine's day, mind you.

0:05:55.258,0:05:57.721
Here was the picture,

0:05:57.721,0:06:00.426
it looked like a heart.

0:06:02.046,0:06:04.617
Of course we knew [br]it was an optical illusion

0:06:04.617,0:06:07.196
and, of course, [br]we never published the picture

0:06:07.196,0:06:08.871
because we would get [br]into all kind of trouble.

0:06:08.871,0:06:13.153
And when we got close, [br]as you will see,

0:06:13.153,0:06:16.874
what happened is that [br]you had these three craters

0:06:16.874,0:06:20.452
that were arranged in a triangle,

0:06:20.452,0:06:27.871
and they looked with [br]a kind of Sun angle and the shade,

0:06:27.871,0:06:30.549
it looked like a heart from a distance.

0:06:30.549,0:06:34.602
So, that is the kind of stuff [br]that you see in the tabloids

0:06:34.602,0:06:37.361
that in the United States [br]we pick out in supermarkets.

0:06:37.361,0:06:39.582
Supermarket counters.

0:06:39.582,0:06:41.803
You know ... "Heart on Eros" ...

0:06:41.803,0:06:44.024
So much for that.

0:06:44.764,0:06:55.095
It was big news that a NASA spacecraft [br]orbited an asteroid on February 12.

0:06:55.593,0:06:59.392
CNN is very loud everywhere it goes,

0:06:59.392,0:07:01.018
including the United States.

0:07:01.418,0:07:03.177
(CNN Speaker): A close encounter

0:07:03.177,0:07:05.805
between a NASA satellite and an asteroid.

0:07:05.805,0:07:09.648
An unmanned spacecraft is now [br]in orbit around an asteroid.

0:07:09.648,0:07:12.114
It's supposed to teach us [br]about these giant rocks,

0:07:12.114,0:07:14.223
and perhaps help scientists to figure out

0:07:14.223,0:07:16.854
how to protect us from a possible collision.

0:07:21.104,0:07:23.763
That is our Trajectory Manager

0:07:23.763,0:07:28.656
who was making, he and his team, [br]most of the calculation.

0:07:28.656,0:07:36.074
(CNN Video)

0:07:36.074,0:07:39.588
And this is the Senator of Maryland.

0:07:39.593,0:07:43.394
And now I am showing you [br]the next episode,

0:07:43.394,0:07:46.107
after we were in orbit for a year.

0:07:46.107,0:07:50.299
We had charted the entire asteroid.

0:07:50.299,0:07:54.272
We were familiar [br]with every little corner

0:07:54.272,0:07:55.928
and every little crater.

0:07:55.928,0:07:58.916
And we just had a little bit of fuel left.

0:07:58.916,0:08:00.663
And we said, "What are [br]we going to do now?"

0:08:00.663,0:08:07.051
Because to maintain a spacecraft[br]in orbit around an asteroid

0:08:07.051,0:08:09.856
that has this kind of shape, [br]like a potato,

0:08:09.856,0:08:14.241
it's very hard and you have [br]to really keep pushing

0:08:14.241,0:08:17.849
and adjusting the orbit by using fuel.

0:08:17.849,0:08:20.223
And we were at the end of the fuel.

0:08:20.223,0:08:24.611
So what would happen is that [br]the spacecraft would drift away.

0:08:24.611,0:08:27.717
So what we did is, I went to NASA

0:08:27.717,0:08:31.054
and persuaded the administrator that

0:08:31.054,0:08:39.635
we were going to try to easy down[br]on the surface of the asteroid.

0:08:39.938,0:08:44.532
He eventually agreed to let us do it.

0:08:44.532,0:08:50.385
So the day came, again it was [br]as I mentioned the year later.

0:08:50.385,0:08:55.685
We had already calculated what [br]the trajectory was going to be like.

0:08:55.685,0:09:01.125
What you see here is [br]the calculated trajectory,

0:09:01.125,0:09:03.048
[it] is the black line.

0:09:03.048,0:09:06.156
And the points are the real-time data.

0:09:06.186,0:09:08.955
We had the laser altimeter [br]that measured

0:09:08.955,0:09:10.770
the distance of the spacecraft [br]from the ground

0:09:10.790,0:09:13.197
by signing a laser, [br]getting the reflection

0:09:13.197,0:09:16.922
and measuring the distance with [br]the precision of about a centimeter.

0:09:16.922,0:09:19.563
So we knew what was happening.

0:09:19.563,0:09:25.022
And we figured that it would take about [br]45 minutes to get down to the ground.

0:09:25.557,0:09:29.339
It seemed like it was going very well.

0:09:29.339,0:09:33.247
I will show you a simulation[br]of what we had done

0:09:33.257,0:09:36.763
with the spacecraft as you see it.

0:09:36.763,0:09:41.866
And in fact, the spacecraft landed

0:09:41.912,0:09:45.143
with the solar panels pointing [br]in the direction of the Sun,

0:09:45.153,0:09:47.729
with the antenna pointing [br]in the direction of Earth,

0:09:47.729,0:09:49.699
and we kept getting data.

0:09:49.699,0:09:51.715
And it went on for a number of days.

0:09:51.715,0:09:57.901
What you see is the pictures [br]that were taken by the spacecraft

0:09:57.901,0:10:02.880
as it was moving into closer [br]and closer to the surface of Eros.

0:10:02.880,0:10:10.485
And at the end we had a resolution[br]which was actually quite good.

0:10:10.485,0:10:14.375
You can see here, [br]this is the last image we had.

0:10:14.375,0:10:18.277
You can discriminate and see rocks

0:10:18.277,0:10:22.779
that were of the order [br]of a few centimeters across.

0:10:22.786,0:10:25.615
Well, that wasn't all.

0:10:26.485,0:10:28.750
We had the opportunity [br]to do other things.

0:10:28.750,0:10:33.124
This is the announcement [br]that we had actually landed.

0:10:33.124,0:10:38.782
And Mr.Goldin, who was [br]the NASA administrator at the time,

0:10:38.782,0:10:42.532
was exceptionally anxious because

0:10:42.532,0:10:46.409
NASA had just crashed [br]a spacecraft on Mars a month before.

0:10:46.409,0:10:50.926
And he was very worried about [br]what was going to happen,

0:10:50.926,0:10:54.185
if this happened again, [br]to NASA's reputation.

0:10:54.185,0:10:56.648
But he was very happy.

0:10:56.648,0:11:01.659
Then, I wanted to show you [br]another thing, here,

0:11:01.659,0:11:05.005
about the details of the surface.

0:11:05.005,0:11:07.183
There is a crater

0:11:07.183,0:11:10.578
that the International Astronomical Union

0:11:10.578,0:11:14.873
in its wisdom decided to name Hios,

0:11:14.873,0:11:18.718
which was the love child of [br]Poseidon and the nymph Hiona.

0:11:18.718,0:11:23.870
So we have a crater on Eros [br]by the name of Hios.

0:11:24.480,0:11:27.160
Nothing to do with the fact [br]that I am from Chios, mind you.

0:11:27.160,0:11:29.629
(Laughter)

0:11:30.221,0:11:37.328
The most important thing, however, [br]is that we finished the project

0:11:37.347,0:11:39.671
and we didn't spend all the money.

0:11:39.671,0:11:44.483
Which had never happened [br]in the history of NASA.

0:11:44.483,0:11:47.275
We had a little ceremony,

0:11:47.275,0:11:52.388
the down payment to NASA of[br]the remainder of 3.6 million dollars.

0:11:52.388,0:11:55.087
In the end we gave them [br]back about 30 million.

0:11:55.087,0:11:59.804
Needless to say, we got a lot of abuse[br]from my other colleagues at NASA centers

0:11:59.804,0:12:02.452
who said, "You never give back [br]money to the government.

0:12:02.462,0:12:04.022
"Shame on you", and so and so .

0:12:04.022,0:12:06.858
But we overcame.

0:12:06.858,0:12:10.604
Now let me tell you about the other part

0:12:10.604,0:12:14.826
of the things that go [br]on uncharted waters.

0:12:14.826,0:12:19.322
What you see here is [br]a view of the solar system.

0:12:19.322,0:12:21.936
Each one of our planets [br]of the solar system

0:12:21.936,0:12:25.709
has already been imaged by spacecrafts.

0:12:25.709,0:12:28.044
The four planets you see here,

0:12:28.044,0:12:30.306
Jupiter, Saturn, Uranus, Neptune

0:12:30.306,0:12:34.186
are all, of course, pictures [br]from the Voyager mission.

0:12:34.186,0:12:39.404
The Voyager mission started [br]in 1977, ladies and gentlemen.

0:12:39.404,0:12:43.727
It was 36 years ago, [br]in a couple of months.

0:12:43.727,0:12:49.991
The original plan was to go [br]to Jupiter and to Saturn.

0:12:49.991,0:12:53.161
It was going to be a four year mission.

0:12:53.161,0:12:55.487
But then it turned out that it was possible

0:12:55.487,0:13:00.023
using gravity assist [br]from Jupiter to go on to Saturn,

0:13:00.023,0:13:01.868
but then also using gravity assist

0:13:01.868,0:13:03.713
from Saturn to go on to Uranus

0:13:03.713,0:13:05.560
and from Uranus to Neptune.

0:13:05.560,0:13:08.266
And that's exactly what [br]we did with Voyager 2

0:13:08.266,0:13:12.333
while we sent Voyager 1 [br]away from the Sun

0:13:12.333,0:13:14.833
and towards the north ecliptic.

0:13:15.363,0:13:22.179
That was a very well planned program,

0:13:22.179,0:13:27.038
it worked well, it provided [br]essentially all new information.

0:13:27.038,0:13:28.536
And I just want to show you

0:13:28.536,0:13:33.970
the spacecraft which [br]is about this size.

0:13:33.970,0:13:36.711
This is the antenna,[br]it points in the direction of Earth.

0:13:36.711,0:13:38.483
It transmits information.

0:13:38.483,0:13:42.325
These here is the instrument [br]from my team.

0:13:43.029,0:13:45.276
And I am pointing it out loud

0:13:45.276,0:13:50.544
because it did some other things [br]that we were very proud of.

0:13:51.100,0:13:53.413
I am showing you this picture

0:13:53.413,0:13:59.295
with President Herbert Walker Bush.

0:13:59.774,0:14:03.291
Not the new one,[br]not the son, the father.

0:14:03.317,0:14:06.115
He had a lot of brains, the father.

0:14:06.115,0:14:07.363
(Laughter)

0:14:07.363,0:14:12.425
He invited us to the White House

0:14:12.425,0:14:17.119
as had done Mr. Reagan before him.

0:14:17.140,0:14:20.456
And I am showing you [br]that simply because

0:14:20.456,0:14:27.757
to point out that the American [br]government, the politicians,

0:14:27.757,0:14:32.792
really appreciate what science [br]does for the country.

0:14:32.792,0:14:34.964
And it is not just NASA,

0:14:34.964,0:14:37.010
it's the National Institute of Health,

0:14:37.020,0:14:39.839
it's all kind of national science foundations.

0:14:39.849,0:14:42.963
And they show it. Effectively.

0:14:42.963,0:14:44.322
With this kind of things,

0:14:44.322,0:14:47.472
by inviting us to lunch, [br]and things like that.

0:14:47.752,0:14:53.487
Anyway. This, after Voyager went [br]past all these four planets.

0:14:53.487,0:14:56.793
This is a simulation, [br]that I am showing you,

0:14:56.793,0:14:59.730
where it was moving away [br]from the Sun

0:14:59.730,0:15:03.618
passed the last planet, [br]the orbit of Pluto.

0:15:03.618,0:15:05.978
And we expected that someday

0:15:05.978,0:15:08.994
we were going to run into this boundary

0:15:08.994,0:15:12.588
and then eventually [br]cross another boundary

0:15:12.588,0:15:15.115
that would lead us into the galaxy.

0:15:15.398,0:15:20.477
The problem was that nobody knew[br]how far these boundaries were.

0:15:20.477,0:15:23.018
We were sort of going in blind.

0:15:23.018,0:15:26.410
There were suggestions that it could be

0:15:26.410,0:15:29.691
a year away, five years away,[br]ten years away.

0:15:29.691,0:15:31.264
Nobody really knew.

0:15:32.508,0:15:35.142
So, how to find it out?

0:15:35.142,0:15:38.123
We had four instruments [br]that were working.

0:15:38.123,0:15:43.794
This is the one that I pointed out [br]before, our team had built.

0:15:43.794,0:15:45.618
And another thing that we did

0:15:45.618,0:15:47.717
is to put a little stepper motor

0:15:47.717,0:15:51.024
that rotated the entire platform [br]back and forth.

0:15:51.024,0:15:53.755
I'll show you a very short video.

0:15:53.755,0:15:54.858
(Buzzing sound)

0:15:54.866,0:15:59.681
That is the kind of sound it made [br]in the laboratory, when it rotated.

0:15:59.681,0:16:03.478
I did this little video for the press

0:16:03.478,0:16:08.684
right after the Neptune encounter.

0:16:08.916,0:16:13.141
I did have hair at one time, you noticed? [br](Laughter).

0:16:13.940,0:16:18.086
We had this little stepper motor

0:16:18.086,0:16:19.916
that was rotating the detectors.

0:16:19.916,0:16:22.927
Just like this simulation shows.

0:16:22.927,0:16:24.498
And you see the colors here.

0:16:24.498,0:16:28.056
You can't see them [br]because of these lights.

0:16:28.056,0:16:32.993
But by rotating around [br]it was possible for us

0:16:32.993,0:16:40.634
to measure the speed and the direction [br]of the hot wind from the Sun,

0:16:40.634,0:16:48.332
which moves at the speed of about[br]1.5 million Km per hour.

0:16:48.332,0:16:51.364
Now, you say, "OK, you told us [br]about these instruments,

0:16:51.364,0:16:54.591
what did you find by rotating this?"

0:16:54.591,0:16:55.684
What we found...

0:16:55.684,0:16:59.357
Here it is, we kept going [br]and going and going.

0:16:59.357,0:17:02.685
The idea was that once [br]we cross this boundary

0:17:02.685,0:17:04.692
we would be out in the galaxy.

0:17:04.692,0:17:08.715
What we found instead[br]is that we ran into a place

0:17:08.715,0:17:14.058
where the solar wind no longer[br]moved away from the Sun.

0:17:14.058,0:17:18.206
And we called that [br]the Stagnation Region.

0:17:18.206,0:17:21.838
We published it in 2011.

0:17:21.838,0:17:24.683
It was not predicted by theory.

0:17:24.683,0:17:30.016
However some models were suggesting [br]that what happens to this wind

0:17:30.024,0:17:34.849
is that it goes to the north direction[br]towards the ecliptic pole.

0:17:34.914,0:17:38.879
Our instrument, however, [br]was only rotating in one plane

0:17:38.879,0:17:42.271
and we couldn't measure [br]the speed up and down.

0:17:42.271,0:17:45.703
So, I asked the engineering team,

0:17:45.703,0:17:50.900
I said "Why don't we turn the spacecraft [br]90 degrees, now and then?

0:17:50.900,0:17:53.685
And then we can measure [br]the north-south direction."

0:17:53.685,0:17:56.251
Mind you, this is a spacecraft

0:17:56.251,0:18:01.162
that had been in space [br]for 34 years already.

0:18:01.162,0:18:05.085
And it is just like getting [br]a dog that's about to die

0:18:05.085,0:18:07.385
trying to teach him new tricks.

0:18:07.385,0:18:09.680
However, what happened is

0:18:09.680,0:18:13.330
that we were able [br]to send the commands,

0:18:13.330,0:18:14.918
and by guiding the spacecraft

0:18:14.918,0:18:18.097
it executed every command perfectly.

0:18:18.097,0:18:21.835
And for two years we have been [br]doing this every two months.

0:18:21.835,0:18:24.686
We rotated the spacecraft [br]in this direction.

0:18:24.686,0:18:28.223
What we found out is that, in fact,

0:18:28.223,0:18:30.456
even this model was also wrong.

0:18:30.456,0:18:34.021
There was no flow of the wind [br]in the north direction

0:18:34.021,0:18:36.086
or in the south direction [br]for that matter.

0:18:36.086,0:18:39.381
So theory failed us again.

0:18:40.420,0:18:44.868
We actually wrote this up[br]and were publishing it

0:18:44.868,0:18:50.838
until we found something very strange[br]that happened last year.

0:18:50.838,0:18:53.495
What you see here,

0:18:53.495,0:18:56.936
and it is the only data that I will show you,

0:18:56.936,0:19:01.704
is the curve for cosmic rays, the intensity.

0:19:01.704,0:19:09.973
And you see that they started increasing[br]right about early May of 2012.

0:19:10.009,0:19:12.826
These are the so-called [br]Galactic Cosmic Rays.

0:19:12.826,0:19:18.678
These are particles that were actually [br]generated by explosions of Supernovae

0:19:18.678,0:19:21.895
millions of years ago[br]in the vicinity of the Sun,

0:19:21.895,0:19:25.939
and were coming from outside [br]the galaxy into our solar system.

0:19:25.939,0:19:28.124
And they began to go up.

0:19:28.124,0:19:32.923
And then, eventually, [br]at about the same time,

0:19:32.923,0:19:35.711
after two or three increases,

0:19:35.711,0:19:38.869
the material that was coming from the Sun,

0:19:38.869,0:19:43.419
never mind what these are, protons and [br]heliums and what we have here, oxygen

0:19:43.419,0:19:45.146
dropped at the same time.

0:19:45.146,0:19:48.292
In other words, [br]the solar material disappears

0:19:48.292,0:19:50.547
and the stuff that was supposed to be coming

0:19:50.547,0:19:52.927
from outside the galaxy [br]-- that's what we believed --

0:19:52.927,0:19:55.794
appeared and increased.

0:19:55.794,0:20:01.960
So we said, "Aha! We actually got out of [br]the solar system and into the galaxy!"

0:20:02.016,0:20:03.888
But we lacked some data.

0:20:03.888,0:20:06.564
This is a picture from a press event

0:20:06.564,0:20:10.225
at the Jet Propulsion [br]Laboratory in Pasadena.

0:20:10.225,0:20:13.270
We were trying to interpret the data

0:20:13.270,0:20:16.756
a few days after [br]we had made that observation.

0:20:16.756,0:20:20.086
Here we have the model [br]of the spacecraft.

0:20:20.086,0:20:23.532
But we didn't have [br]all the data that we needed.

0:20:23.532,0:20:28.282
Namely, we couldn't measure the density[br]of the atmosphere of the galaxy,

0:20:28.282,0:20:30.471
if I can put it that way.

0:20:30.471,0:20:35.142
Until April of this year.

0:20:35.142,0:20:36.687
I don't know if you can hear the sound,

0:20:36.687,0:20:39.882
maybe you can turn it up a little bit?

0:20:39.882,0:20:41.295
(Whistling sound)

0:20:41.295,0:20:44.747
OK. Now, what are these,

0:20:44.747,0:20:49.008
is, we have some antennas on the spacecraft.

0:20:49.008,0:20:52.661
And in the vicinity of the spacecraft[br]something happened

0:20:52.661,0:20:56.011
and all these electrons [br]began to oscillate back and forth.

0:20:56.011,0:20:57.956
When the electrons oscillate [br]in a magnetic field

0:20:57.956,0:20:59.792
they produce sounds.

0:20:59.792,0:21:02.358
And when they produce this sound

0:21:02.358,0:21:07.086
we are able to determine [br]the density of the material

0:21:07.086,0:21:08.480
around the spacecraft.

0:21:08.480,0:21:13.423
What you see here is that [br]we were able to determine

0:21:13.423,0:21:17.767
that it was 0.1 per cubic centimeter.

0:21:17.767,0:21:19.347
You would say, [br]"What does that mean?"

0:21:19.347,0:21:24.049
Well, it was 50 times [br]what we had before.

0:21:24.049,0:21:28.776
When we were in the solar wind,[br]inside our solar atmosphere.

0:21:28.785,0:21:31.567
And because most models predict

0:21:31.567,0:21:35.330
that the density in the galaxy is about 0.1,

0:21:35.330,0:21:38.865
we knew that we had actually arrived.

0:21:38.865,0:21:46.449
So, we had a meeting at my lab[br]back in Johns Hopkins in September.

0:21:46.524,0:21:50.089
We looked at all the data [br]and we finally decided

0:21:50.089,0:21:53.588
that it was safe [br]to issue a press release

0:21:53.588,0:21:59.128
that actually we had crossed

0:21:59.128,0:22:05.687
the boundary with the galaxy[br]on August 25 of 2012.

0:22:05.687,0:22:09.100
So, think about this:

0:22:09.101,0:22:11.785
a hundred and ten years ago,

0:22:11.785,0:22:14.880
it was when the Wright brothers

0:22:14.880,0:22:19.068
flew a... you could call it an airplane

0:22:19.068,0:22:21.881
-- that's what they called it --

0:22:21.881,0:22:25.221
at an altitude of few meters[br]for about 30 seconds.

0:22:25.221,0:22:28.664
And then about 50 years later

0:22:28.664,0:22:33.527
there was the launch [br]of the first Earth satellite, Sputnik.

0:22:33.527,0:22:38.423
It went outside the Earth's [br]atmosphere for the first time ever

0:22:38.423,0:22:42.189
in our history, in humanity's history.

0:22:42.189,0:22:49.114
And it got to an altitude [br]of 946 km, to be exact.

0:22:49.114,0:22:54.932
And then another 55, or so, years later,

0:22:54.932,0:22:58.731
we had the exit of the first [br]spacecraft, Voyager 1

0:22:58.731,0:23:07.604
from the atmosphere of the Sun[br]at an altitude of 18.2 billion kilometers.

0:23:07.604,0:23:09.479
To give you an idea:

0:23:09.479,0:23:12.191
the signal that we get from Voyager,

0:23:12.191,0:23:15.130
when it leaves Voyager, [br]it travels with the speed of light,

0:23:15.130,0:23:20.148
and it takes 17 hours and 20 minutes[br]to get from there to Earth.

0:23:20.148,0:23:24.313
The light from the Sun to come to Earth[br]only takes 8 1/2 minutes.

0:23:24.313,0:23:27.547
So you can imagine [br]how far this spacecraft is.

0:23:27.550,0:23:31.986
To give you the bottom line, so to speak.

0:23:31.986,0:23:35.025
Here we are. [br]Voyager 1 is in the galaxy.

0:23:35.025,0:23:38.212
Voyager 2 is not there yet, [br]it is a little slower,

0:23:38.212,0:23:42.080
so we expect it will go out at some point.

0:23:43.590,0:23:48.088
Finally, I can imagine that [br]there was a rooster there

0:23:48.088,0:23:50.701
that said "People of Earth, [br]welcome to the galaxy!",

0:23:50.701,0:23:52.384
(Laughter)

0:23:52.384,0:23:55.147
on August 25, 2012.

0:23:56.387,0:24:01.047
I posed the question in the beginning: [br]"Are there limits?"

0:24:01.234,0:24:06.902
I think you can imagine that my answer [br]to that is "No, of course no."

0:24:06.902,0:24:12.314
I think limits constrain our imagination

0:24:12.314,0:24:16.093
and retard progress, I think.

0:24:16.101,0:24:20.263
So, we don't need any limits.

0:24:20.263,0:24:21.551
And there are none.

0:24:21.554,0:24:23.134
Thank you very much.

0:24:23.134,0:24:31.761
(Applause)