NASA is planning to land its OSIRIS-REx probe on the asteroid Bennu, which is more than 120 million kilometers from Earth, in July 2020.

The NASA scientists aim to collect rock and sand samples from the asteroid. But they say it will be difficult to find a safe landing site because Bennu is covered with more boulders than they expected.

The Hayabusa2 probe landed on the asteroid Ryugu in February in similar rocky conditions. The probe made a pinpoint landing in a target area with a diameter of about 6 meters.

The Hayabusa2 team gave the NASA researchers advice on how to make a precision-guided landing of a spacecraft.

University of Arizona Professor Dante Lauretta is the leader of the OSIRIS-REx mission.