The nation's Hayabusa2 space probe, launched in December 2014, will make its closest approach to the Earth on Thursday as it performs a swing-by to set it on a course toward its target asteroid, 300 million kilometers away.
The probe, which has until now had an orbit similar to the Earth's orbit around the sun, will reach an altitude of only 3,100 km shortly after 7 p.m., the space agency said. Gravity will then cause it to change direction and pick up speed — a method used by spacecraft to save fuel on long missions.
To put Hayabusa2 on the correct orbit with the swing-by requires precise maneuvering. This is like "aiming at a bug at the top of Mount Fuji from Tokyo," Hiroshi Takeuchi of the Japan Aerospace Exploration Agency said. The 3,776-meter mountain is Japan's highest peak.