- Three, two, one! (hands clapping)
- [Narrator] A spacecraft intentionally crashed
into an asteroid on September 26th.
- Oh, wow. (scientist laughs)
(group applauds)
- [Narrator] As part of a roughly $325 million mission.
(group applauds) - [Scientist] All right!
- [Narrator] The collision was part
of NASA's Double Asteroid Redirection Test,
also known as DART.
- This is a first for humankind.
- [Narrator] So why did NASA crash
a multimillion dollar spacecraft into an asteroid
and what will scientists learn from it?
There are currently over one million known asteroids,
according to NASA.
They vary in size, shape, and composition
and move in different orbits around the sun.
Some even cross paths with Earth's orbit,
but typically don't pose a threat to our planet.
But asteroid impacts have occurred
throughout Earth's history.
Scientists believe an asteroid impact
led to the extinction of dinosaurs.
In order to test one type of technology
that can mitigate a possible future asteroid impact,
NASA launched DART.
- [Scientist] Three, two, one.
(rocket flare roars)
And lift-off of the Falcon 9 and DART.
- [Narrator] The DART spacecraft
launched into outer space almost 10 months ago.
The school bus-sized spacecraft
traveled millions of miles through space
and eventually collided with an asteroid
about the size of the Washington Monument.
This is NASA's first ever planetary defense test mission.
- Planetary defense in general
is aimed at finding out what's out there,
figuring out if anything is out there
that we need to worry about,
and when we need to worry about it.
- [Narrator] Andy Rivkin,
an investigation lead on the DART team,
identifies asteroids and develops methods
to mitigate the risk they pose to planet Earth.
He says this real-world experiment
will prepare defense methods
against future hazardous asteroids.
- It's the first time that we are rearranging
a celestial body's orbit.
- [Narrator] DART targeted
the binary asteroid system Didymos,
which is composed of two asteroids,
Didymos, the larger asteroid,
and its smaller moonlet, Dimorphos.
This is what scientists call kinetic impactor technology,
which involves using spacecraft
designed to deflect a near-Earth object
to change its orbit so that it misses our planet.
According to NASA,
DART collided into the asteroid
at roughly 14,000 miles per hour
and the impact occurred
around seven million miles away from Earth.
But navigating a small spacecraft
leaves little room for error.
- You can't sit there with a joystick
and steer yourself in that fast.
- [Narrator] This is why NASA created SMART Nav,
a new technology system that allows the spacecraft
to direct itself entirely on its own,
without human intervention.
Little was known about the composition of Dimorphos
before the collision;
only pixelated telescopic and radar images
have provided small clues about its surface.
But now scientists will be able to study images of the crash
which were captured by an Italian CubeSat called LICIACube.
The images will help scientists determine
what kind of impact DART had on Dimorphos,
including a potential crater on the surface of the asteroid.
Scientists are also researching
how the impact changes the asteroid's orbit.
Before impact, it took Dimorphos
approximately 11 hours and 54 minutes to orbit Didymos,
but that is likely to change now.
- We don't know if it will change it
to more like 11 hours and 42 minutes
or 11 hours and 46 minutes.
- [Narrator] In order to measure a change to the orbit,
Rivkin and his team will collect data
on the asteroid system's light curves,
which are measurements of a celestial body's brightness
at certain intervals.
Using the light curves,
scientists will be able to compare
the new orbit to the old orbit,
showing how much impact DART made during the collision.
In October 2024,
the European Space Agency will launch a mission called Hera
which will reach Dimorphos in 2026
to conduct detailed post-impact surveys on the asteroid.
Hera will advance scientists' understanding
of Dimorphos' internal properties
and the outcome of the DART test.
Though DART is only a test
and Dimorphos isn't a threat to planet Earth,
carrying out a real-world test will inform scientists
whether this type of planetary defense
is a reliable option against future asteroids
headed towards Earth.
- We don't wanna add to people's anxieties,
we want to demonstrate
that we can handle asteroid deflections.
(bright music)