The Hayabusa2 on Thursday released a robotic explorer bound for the surface of an asteroid in the probe's final task before returning to earth, the Japan Aerospace Exploration Agency (JAXA) said.

The Minerva-II2, a small rover attached to Hayabusa2, began its descent toward the surface of the Ryugu asteroid at around 1 a.m. Japan time. Its primary task will be to research the asteroid's gravity. Previous plans for surface observations were scrapped due to glitches, according to JAXA.

Observing the explorer's descent to the surface will be the last mission for the probe before it leaves the asteroid in November or December, the agency said.

Hayabusa2, which was tasked with gaining clues about the formation of the solar system and the origin of life, is scheduled to return to Earth around the end of 2020.

The rover, which was separated from the space probe at 1 kilometer above the asteroid's surface, will orbit Ryugu's equator about eight times over five days before touching down on the surface.

Hayabusa2 will remain approximately 8 to 10 km above the asteroid to take photographs.

The rover is the last of three explorers that make up the Minerva-II robot vehicles installed on Hayabusa2. The first two rovers successfully landed on the asteroid in September last year and took images of its rocky surface.

Launched in December 2014 from the Tanegashima Space Center in Kagoshima Prefecture, Hayabusa2 reached Ryugu in June last year.

The probe touched down on Ryugu twice and succeeded in collecting the first-ever subsurface asteroid samples in July after creating an artificial crater in April by shooting a copper projectile at the asteroid.