Japan hopes to land a spacecraft on an asteroid -- and has successfully begun orbiting it

Artist concept of Haybusa2 approaching asteroid 162173 Ryugu. Picture: JAXA/Akihiro Ikeshita

A previous version of this story suggested the spacecraft would land on 162173 Ryugu immediately. Hayabusa2 will first orbit the asteroid for an unspecified time to find suitable landing and experimentation sites.

Japan hopes to land a spacecraft on an asteroid 3.2 billion kilometres away, and it’s letting people on Earth watch the approach, live.

Coverage starts around 4.30pm AEST as Hayabusa2 approaches asteroid 162173 Ryugu after a voyage through space that began on December 3, 2014.

This is the latest image of Ryugu, taken from 40km away on June 24:

Picture: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, Aizu University, AIST

Although this image of a lonely rock in space is probably more striking:

Picture: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, Aizu University, AIST

The first thing researchers at the Japan Aerospace Exploration Agency (JAXA) have noted is Ryugu actually looks more like a diamond than a sphere. Or an eight-sided dice, if you’re into that.

JAXA prefers to think of it as similar to that of a firefly gemstone, or fluorite, which are popular in Japan. It says that particular shape is “scientifically surprising and also poses a few engineering challenges”.

“First of all, the rotation axis of the asteroid is perpendicular to the orbit. This fact increases the degrees of freedom for landing and the rover descent operations,” it notes.

“On the other hand, there is a peak in the vicinity of the equator and a number of large craters, which makes the selection of the landing points both interesting and difficult.”

And because of the asteroid’s angular shape, the “direction of the gravitational force on the wide areas of the asteroid surface to not point directly down”.

However, “morale is rising” at the prospect of the challenge JAXA faces, and it’s happy to let the world watch.

Despite the 3.2 billion kilometre journey, the pair will rendezvous just 280 million kilometres from Earth, and Hayabusa2 is right now preparing to deploy a range of vehicles to the surface of Ryugu.

During the next one and a half years, four probes will be dropped and freefall to Ryugu from 60 metres. One container will deploy two 18 centimetre-diameter rovers which move in hops created by internal rotations and use stereo and wide angle camera, and thermometers.

The other container will deploy a similar hopping rover that will use LEDs to illuminate and detect dust particles.

The biggest rover, MASCOT, is still tiny — about 30 centimetres all round. It’s a German/French co-operative effort that carries an infrared spectrometer, a magnetometer, a radiometer and a camera.

How to make a hole in an asteroid

Hayabusa2 itself will collect surface samples and return them to Earth for analysis toward the end of 2020. How it does that is where things get interesting for the rest of us.

Hayabusa2 is carrying a “collision device”. Sometime around autumn next year, it will deploy the device along with a separate small camera.

As the mother ship evacuates to the other side of the asteroid, the collision device will explode just above the surface of Ryugu, driving a two kilogram chunk of copper into Ryugu’s surface.

Picture: JAXA

That impact will hopefully create a small crater on the surface. JAXA is counting on the deployed camera to catch this all in action.

If all goes well, Hayabusa2 can descend to the crater and examine the underground makeup of Ryugu.

The countdown is on, so if you want to watch a landing 280 million kilometres away in space, stayed tuned in here:

If it successfully completes its mission, Hayabusa2 will be only the second time a spacecraft has returned samples from an asteroid to Earth. JAXA also owns the honour of being the first to achieve that feat, when the original Hayabusa brought back chunks of 25143 Itokawa in 2010.

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