Japan's space agency made history.

It became the first country to land not one,

but two rovers onto an asteroid,

and already, the two unmanned rovers have sent back

the first images while on the surface.

And no, so far, it's looking like there are no alien cities

on its surface, but this mission, called Hayabusa2,

could ultimately help solve one

of the grandest scientific mysteries of all,

where did life on Earth come from?

(gentle orchestral music)

Scientists have been studying asteroids for years.

NASA, for example, landed its NEAR Shoemaker spacecraft

on Asteroid Eros in 2001,

but it's Japan's space agency that is the first

to deploy a pair of rovers to explore an asteroid's surface.

Japan launched the Hayabusa2 mission in December 2014,

so, it has already been about 3 1/2 years in the making.

The spacecraft rendezvoused with its target in June 2018,

snapping a series of pictures

that revealed the asteroid's shape.

The asteroid of choice was 162173 Ryugu,

or Ryugu for short.

In Japanese, it refers to a magical, underwater

dragon palace.

Now, the asteroid flies through space

around the sun every 16 months,

conveniently, between the orbits of Earth and Mars,

making it an ideal target for this mission,

which, if all goes according to plan,

it will return a sample of the asteroid to Earth

by the early 2020s.

As the spacecraft flew closer to the asteroid's surface,

it prepared to deploy its first two unmanned rovers.

But these guys aren't your typical space rover.

They're slightly bigger than the size of a large iPhone,

measuring just 7 by 18 centimeters,

and they won't be driving around on the asteroid's surface.

They'll be hopping.

Yeah, you heard that right, hopping.

Japan designed the rovers with a spinning cylinder

inside that gives it the power to hop

about a few meters at a time.

This reduces the risk of getting stuck

on the rocky, uneven surface,

but it doesn't come without its own risks.

Asteroids are relatively small

and therefore, have a weak gravitational pull,

and even by asteroid standards, Ryugu is tiny.

It's less than a kilometer across,

making it no larger than a few city blocks.

So, if the rovers hop too high,

they could potentially go flying off into space.

But, so far, the mission looks good.

The rovers have already achieved their first hop.

Now, this may be the first time Japan has landed

on an asteroid, but it won't be the last.

These two rovers are just the first of four

that Japan aims to land on Ryugu.

The other two rovers are scheduled to land

within the next year.

In the process, Japan hopes to collect and return

a sample of Ryugu to Earth,

so that scientists can study it in more detail,

looking for traces of water and organic material.

If it turns out that asteroids like Ryugu

contain similar material that we see on Earth,

it would be strong evidence for the idea

that life on Earth first came from asteroids

billions of years ago.

But this is a mystery that we can only answer

if we study asteroids directly.