[Music]
There are many important reasons for studying asteroids
like the target of OSIRIS-REx, asteroid Bennu.
First and foremost, for me especially, they're geologic
remnants from the dawn of our solar system.
They're literally the first material that formed around our
star, and they represent the building blocks of planets, and
we hope, in the case of Bennu of life, and the reason that Earth
may be a habitable planet in the form of delivering water and
other important volatile material.
When we look at asteroids which are these primitive objects,
these little leftover pieces from solar system formation, and
we find they may have organics, then that tells us perhaps the
conditions for life could have erupted anywhere in the solar
system, and Earth was just right.
When we study meteorites, we think they represent these
asteroids and their different histories, but they've all
interacted with the Earth's atmosphere, its biosphere, its
hydrosphere, and so we don't know what effect just
interacting with the Earth has had on these meteorites.
We really want to get samples that are pristine, and so we can
do all of those things through this mission.
OSIRIS-REx is a mission in the NASA New Frontiers Program.
Our objective is to travel out to a near-Earth asteroid named
Bennu, survey that object in great detail to understand its
geology, its mineralogy and composition, ultimately select a
single location on the asteroid's surface to acquire a
sample, and return that material back to the Earth for scientific
analysis.
Asteroid Bennu is a fragment of the early solar system, an
un-melted, unaltered piece of the origin of the solar system.
It preserves the ingredients, the raw materials that went into
the formation of planets, the formation of life.
By bringing a sample back to the Earth, such as OSIRIS-REx will
do with samples of Bennu in 2023. we'll be able to look at
the samples in laboratories around the world, to understand
in great detail the nature of the sample and its place in the
origin of the solar system.
The OSIRIS-REx spacecraft launched in 2016, and it's
actually taken us two years to get to the asteroid Bennu, and
in that time we had an Earth flyby.
So, we used an Earth flyby in 2017 to change the plane of our
orbit to match Bennu's orbit plane, and it's also provided a
great opportunity from a flight dynamics perspective to really
calibrate our models and learn how to fly the spacecraft which
will help us in the really challenging part of the mission,
which is orbiting in the low-gravity environment of the
asteroid.
Over the past few months, the flight dynamics team has been
getting images of the asteroid Bennu, and it started out as
just a very small point source in the camera, and it's been
getting bigger and bigger and bigger in the field of view.
And that's allowed us to perform optical navigation, to refine
our prediction of the asteroid's orbit, and allow us to more
precisely navigate and target our approach to the asteroid.
As OSIRIS-REx approaches the asteroid, we've done a series of
braking maneuvers called Asteroid Approach Maneuvers to
slow down the spacecraft, so that we can get into orbit
around the asteroid later this year.
We're also taking lots of images of Bennu to understand its
rotation, look for natural satellites, and potential dust
plumes.
This is an extremely exciting time on OSIRIS-REx as we're just
poised at arrival at Bennu.
And one of the most exciting things to us, and relieving too
to the engineers, is how closely the asteroid has resembled what
we had predicted.
Early on our science team, prior to launch, had come up with of a
model of what they thought the asteroid would look like, based
purely on ground-based radar observations from Arecibo, and
from that they created a reference asteroid that we used
as the requirements to design the mission against.
But no one could be sure that the asteroid would really look
like the scientists had predicted, so it's been a
tremendous relief to us to find that the actual Bennu is very
similar to what the scientists had predicted.
So, the science team really nailed it.
Well right now as we're approaching asteroid Bennu,
we're looking for debris or other objects that are orbiting
the asteroid just in case we need to avoid those.
And then once we arrive on December 3 we'll perform
Preliminary Survey, and in Preliminary Survey we fly over
the north pole, south pole, and the middle of the asteroid.
This helps us to map the gravity of the asteroid and understand
how to operate near such a small body.
Additionally, this will be the first time that we get close-up
pictures of the surface, and we'll know how smooth or rocky
the surface that we're going to study is.
As we get closer to asteroid Bennu, we'll begin to map its
surface in higher detail.
What we'll be able to do is first identify the distribution
of rocks and particles that might pose a hazard to the
sampling mechanism on the spacecraft, and we'll also get a
better sense of what the shape of Bennu is like at smaller
scales.
Looking at Bennu in more and more detail is going to help us
identify all the areas that we shouldn't go to grab a sample
from.
Throughout 2019 we'll be doing global characterization of the
asteroid, basically making maps of the entire surface.
We're interested in its topography.
Are there craters?
Where are the boulders, the valleys, the mountains of the
asteroid?
And then we want to understand the distribution of geologic
materials: are we finding different patches of minerals in
one location versus another, and why are certain areas that have
a composition and others maybe different?
We're going to be looking most importantly for areas where we
can collect a sample.
OSIRIS-REx will collect a sample from Bennu using our TAGSAM,
which is the Touch And Go Sample Acquisition Mechanism.
What that is, is an arm connected to this sampler head
that you see here.
This is similar in size to an air filter from a car.
How this mechanism works is there's compressed gas that is
released that will stir up the regolith from Bennu, store it
into this canister, which we will then put inside of our
sample release capsule and bring back to Earth.
We will collect the sample of Bennu in 2020 and return it to
Earth in 2023.
Once we're in the vicinity of our home world, about
four-and-a-half hours before impacting the top of the
atmosphere, the spacecraft spins up and releases that sample
return capsule.
The spacecraft fires its engines to perform a deflection burn,
going off into orbit around the sun, and the return capsule
enters the Earth's atmosphere, targeting a landing in the Utah
desert.
I'll be there on site when we open that capsule up and we see
those samples for the first time, and science begins at that
point on the next phase of the mission, the sample analysis
period.
[Music]
[Satellite beeping]