Japan's Historic Asteroid Space Probe Is Heading Back to Earth

After making history more than 180 million miles from Earth, Japan's asteroid mission space probe is on its way back — the first to collect samples from under an asteroid's surface, reports Nature. The spacecraft is expected to arrive in late 2020.

It's just the latest in a string of successes for JAXA (Japan Aerospace Exploration Agency) and the asteroid-exploring project.

In July, in one of the final chapters of a years-long mission, the agency landed its Hayabusa-2 spacecraft on the asteroid Ryugu to collect sub-surface samples from the asteroid.

"We've collected a part of the solar system's history," project manager Yuichi Tsuda said after the successful landing was confirmed. "We have never gathered sub-surface material from a celestial body further away than the moon."

Earlier this year in February, Hayabusa-2 landed on the asteroid for the first time, collecting samples from the surface.

You can see that touchdown moment in the video below.

To retrieve the samples, the spacecraft fired a metal "bullet" towards the surface to catch particles from the impact. Hayabusa-2 used a sampler horn to collect any airborne particles.

The reason JAXA is so interested in Ryugu is because it's a carbon-rich (C-type) asteroid from the early days of our solar system and contains valuable minerals that can be beneficial for life here on Earth.

"We think we understand how carbon-rich asteroids migrate from the asteroid belt to become near-Earth asteroids, but the samples from Ryugu will allow its history to be explored," Alan Fitzsimmons of Queen's University Belfast told BBC News. "We believe carbon-rich (C-type) asteroids may have significant amounts of water locked up in their rocks. It's possible such asteroids may have brought to Earth both the water and the organic material necessary for life to start...These samples will be crucial in investigating this possibility."

But sample collection isn't the only mission on Ryugu.

Rovers capture first images

On Sept. 22, JAXA announced that Hayabusa-2 had successfully dispatched and landed two small Minerva-II1 rovers on the surface of the 1-kilometer-wide asteroid. The first pictures sent back, while the rovers themselves were "bouncing" over the surface, are blurry, but nonetheless remarkable.

The rovers explored its surface and collected data. Each was equipped with wide-angle and stereo cameras, as well as motor-powered internal rotors that allowed them to "hop" from location to location.

Just several days after landing on the asteroid, the two rovers transmitted clearer images and a short video that showed the landscape and topography in greater detail.

"The project team is fascinated by the appearance of Ryugu and morale is rising at the prospect of this challenge," project manager Yuichi Tsuda said in a JAXA press release. "Together with all of you, we have become the first eyewitnesses to see asteroid Ryugu. I feel this is an amazing honor as we proceed with mission operations."

Surface party to grow

Two more robotic spacecraft also touched down on Ryugu's surface. The first, called Rover 2, used optical and ultraviolet LEDs to analyze lingering dust over the surface of the asteroid. The second, called MASCOT, studied the magnetic properties of Ryugu and non-invasively analyzes its mineral composition.

MASCOT successfully landed on Oct. 3 and also tweeted, "And then I found myself in a place like no place on Earth. A land full of wonder, mystery and danger! I landed on asteroid Ryugu!"

The rover's life was short-lived and only last 17 hours, which was expected. But during that time, it was busy measuring magnetic fields, determining surface temperatures and capturing images at different wavelengths.

You can see an animation of MASCOT's landing below.

A prelude to asteroid mining?

Scientifically, Ryugu is an attractive candidate to researchers because it's thought to contain primitive materials that could shed light not only on the origins and evolution of our own solar system, but also life in general. For the nascent asteroid mining industry, the mission also stands as an interesting case study in the retrieval and return of samples back to Earth.

According to the Asterank website, operated by mining company Planetary Resources, Ryugu's rich composition of nickel, iron, cobalt, water, nitrogen, hydrogen and ammonia make it worth $82.76 billion.

"Learning about asteroids is important for the future of space exploration," project manager Hitoshi Kuninaka said in an interview with Spaceflight Now. "This is a difficult mission, but in order for humans to expand from Earth into space, it will be necessary to meet challenges. We need a lot of technology and information about the solar system, and Hayabusa2 will make a big step in these areas to help us be ready to plan and collaborate in the next step of space exploration."