WEBVTT FILE

1
00:00:00.000 --> 00:00:03.003
[music throughout]

2
00:00:18.551 --> 00:00:20.887
The Trojan asteroids
are found in Lagrange points,

3
00:00:21.321 --> 00:00:25.058
which are these special places that lead
or follow a planet in its orbit

4
00:00:25.392 --> 00:00:30.230
by 60 degrees, and it's sort of where
the gravitational force of the planet

5
00:00:30.230 --> 00:00:33.733
and the gravitational force
of the Sun all cancel out.

6
00:00:33.767 --> 00:00:37.504
So if you put an object there,
it will stay there for a long period

7
00:00:37.504 --> 00:00:38.905
of time, basically forever.

8
00:00:38.905 --> 00:00:42.375
So when we see objects there,
these are objects

9
00:00:42.375 --> 00:00:45.945
that we know were in place
a very long time ago.

10
00:00:48.081 --> 00:00:49.182
So if you just take

11
00:00:49.182 --> 00:00:52.685
a random asteroid
and just put it in the outer Solar System,

12
00:00:52.685 --> 00:00:54.421
the gravitational force

13
00:00:54.421 --> 00:00:58.291
of the four outer planets will just clear
them out in a very short period of time.

14
00:00:58.925 --> 00:01:00.727
So they'll basically be gone.

15
00:01:00.727 --> 00:01:04.564
So the only places
it turns out in the outer Solar System

16
00:01:04.564 --> 00:01:08.368
where you can find stable regions
are these Lagrange points.

17
00:01:08.401 --> 00:01:13.173
Lucy in particular,
is going to go after the Jupiter Trojans.

18
00:01:13.473 --> 00:01:16.276
We're trying to see a type of object

19
00:01:16.643 --> 00:01:21.448
that represents and constrains
the formation of the outer planets.

20
00:01:21.915 --> 00:01:26.820
And you need to go to these Lagrange
points in order to see that kind of thing.

21
00:01:28.221 --> 00:01:29.722
One of the really groovy

22
00:01:29.722 --> 00:01:35.662
aspects of our mission is its trajectory,
because we're visiting

23
00:01:35.929 --> 00:01:39.399
a record number of objects
like these Trojans.

24
00:01:39.899 --> 00:01:43.903
And we do that with this very complicated
dance, particularly in the beginning,

25
00:01:43.970 --> 00:01:49.642
where we are using the earth
actually as a gravitational slingshot.

26
00:01:49.876 --> 00:01:53.580
So Lucy will start off in an orbit
very similar to the Earth,

27
00:01:53.847 --> 00:01:58.518
and then gravitational encounters
with the Earth will actually pump it up.

28
00:01:58.518 --> 00:02:02.422
So it gets out to the Lagrange points
near Jupiter's orbit.

29
00:02:03.323 --> 00:02:06.493
So if you're going to understand
how planets like the Earth formed,

30
00:02:07.327 --> 00:02:09.762
you have to understand
how the bigger planets

31
00:02:09.762 --> 00:02:13.233
which sort of dominated
the whole process came to be.

32
00:02:13.233 --> 00:02:15.435
And that's what Lucy is going to do.