The Lucy Mission is going to fly past seven asteroids in
twelve years with one spacecraft. We are going to an
amazing variety of objects with this mission, and it’s really
almost pure luck that allowed us to get as many rich targets as
we are. Literally, the planets were aligning to allow us to do
this mission. The Lucy Mission is named after the Lucy fossil,
the Australopithecus fossil, that was discovered in the 1970s
in Ethiopia. And just like the Lucy fossil transformed our
understanding of hominid evolution, the Lucy Mission will
transform our understanding of Solar System evolution. Trojan
Asteroids are an interesting population of small bodies that
are left over from the formation of the planets. And they lead or
follow Jupiter in its orbit by roughly sixty degrees. If you
just look at the gravitational attraction of the Sun and
Jupiter and put something exactly sixty degrees in front
of Jupiter, it’s stable forever. So, as a result these objects
are really the leftovers of planet formation. The stuff that
went into growing Jupiter and Saturn are now trapped in these
locations. The very first asteroid we get to is a main
belt asteroid named DonaldJohanson. We named that
asteroid in honor of the researcher who found the Lucy
fossil. We’re going to use that asteroid to do a rehearsal on
our spacecraft to make sure that everything is working properly
so that when we get to the Trojan asteroids, we’re ready to
go. We’re visiting both of the Trojan swarms. In the first
orbit, we’re going into the leading swarm and we’re going to
encounter four Trojan targets: Eurybates, Polymele, Leucus, and
Orus. And from this, we’re going to sample the diversity in
sizes, colors, and compositions. The first two flybys happen just
about thirty days apart, so it’s going to be a pretty busy
kickoff to the season of exploring the asteroids in the
L4 swarm. And then, we’ll fly past Earth again and out to the
L5 swarm. The final object we’re visiting, which I must admit is
my favorite, is a binary object. So, that’s two Trojans that
orbit a common center of mass, it’s called Patroclus and
Menoetius. These objects are nearly identical in size that
orbit one another. From the Lucy Mission we’re going to study the
diversity of our targets because that tells us something about
their origin and where they came from. The interesting thing
about small bodies in general is that they are the leftovers of
planet formation. If you look at the eight planets that we know
about, for example, they are highly processed because of
internal processing. These asteroids are objects that
really haven’t changed much from when the planets assembled
themselves. As a result, by studying them we can figure out
the physical conditions of the early Solar System as well as
how the planets grew and how they moved around early on. All
of that will help us form a detailed picture of what these
objects really look like because right now our best images are
just a point of light. Even using the Hubble Space Telescope
or adaptive optics on large, ground-based telescopes, we
can’t see surface details. And it’s going to take the Lucy
Mission to go to these targets and see what they’re really made
of and what they look like.