Japan's Hayabusa-2 spacecraft mission has started its journey back to Earth after an exploration of the asteroid Ryugu. The probe will land on Earth sometime in December 2020, with eagerly awaited samples of the surface of the asteroid.

The Japan Aerospace Exploration Agency, JAXA, started the process of the return journey on November 13. The probe is expected to break free of the asteroidโ€™s gravity on November 18, after which its ion engine will start for its return.

Hayabusa-2 was deployed in December 2014 to explore the asteroid Ryugu, which is some 300 million kilometres from Earth. Several probes were dispersed after landing to collect samples and pictures of the asteroid. Prominent among them was the French-German Mobile Asteroid Surface Scout or MASCOT.

Source: JAXA

MASCOT is equipped with sensors and can take images at multiple wavelengths. It carries a microscope to help investigate the material collected and can gauge the surface temperature and measure the magnetic fields. The battery life of MASCOT is 16 hours, which is more than enough to collect enough data for the scientists. Two smaller rovers, MINERVA-!! Micro-rovers were also dropped on the surface of asteroid Ryugu. The magnetic field on the asteroid is low, which enabled the rovers to jump longer and higher. It is believed the probes were able to travel 49 feet in one jump and stay above the surface for more than 15 minutes.

The excavation of the inner samples was done by firing an impactor, which exploded above the surface of the asteroid, firing two-kilo copper bullets to form a crater on the surface, making it easier to collect the inner samples with a robotic arm. Hayabusa-2 was able to touch down on the surface of the asteroid twice to collect the sample material.

Hayabusa-2 has been beaming images of the surface back to JAXA of the asteroid for months. The pictures have become clearer and bigger with the probe getting nearer to its surface.

Hayabusa-2 was almost 18 months on the asteroid and will now take another year to reach the earth before scientists can take a look at the collected samples.

JAXA has launched an imaging campaign, Goodbye Ryugu, in reverse now, which will last for 5 days till November 18. The space mission will host a new image sent by the probe every half hour on its website. As Hayabusa2 nears the earth, it will eject a capsule containing the samples. The capsule will land in the Australian Outback, the same place where its predecessor, Hayabasu, landed with its samples. Hayabusa-2 will not burn out and will be used for another mission later, though JAXA has not revealed any plans for it yet.

The material collected by the probe is expected to contain carbon and other organic matter. This will help scientists to know more about the formation of asteroids and the solar system. It will help throw light on the formation of life in the universe and even how elements from space helped form life on Earth. Hayabusa-2, the size of a big refrigerator, is the successor of Hayabusa, which means falcon in Japanese. It was the first asteroid explorer by JAXA to be sent into space.

The Hayabusa-2 mission cost around 30 billion yen ($260 million), according to sources.