Japan's Hayabusa2 space probe is descending toward the asteroid Ryugu for an unprecedented mission collecting underground rock samples. The landing is scheduled to take place Thursday morning Japan time.
Hayabusa2 began its descent from an altitude of 20,000 meters shortly before 11:00 a.m. on Wednesday, at a speed of 40 centimeters per second.
After about 10 hours, as the probe was 5,000 meters above Ryugu, it slowed its rate of descent to 10 centimeters per second as planned.
Mission controllers believe Hayabusa2 had descended to an altitude of 1,700 meters as of 6:00 a.m. on Thursday. It will attempt a landing at around 10:05 a.m.
The probe made its first touchdown in February. The Japan Aerospace Exploration Agency believes it successfully collected surface rock samples from the asteroid.
This time, Hayabusa2 will try to collect rocks from below the surface, which are believed to be unaffected by cosmic rays. Scientists believe such unaltered rocks will shed more light on the origins of life and the formation of the solar system.
In April, Hayabusa2 fired a metal object into Ryugu's surface and created a crater. The probe will land near the crater to collect rocks ejected by the impact.
JAXA says it is the first-ever attempt to probe the inside of an asteroid. But the agency said the mission is difficult as the landing site is only about seven meters in diameter.