The BepiColombo mission cleared a major milestone this week in the final stretch of an eight-year interplanetary voyage to Mercury, the hard-to-reach, scorching hot iron world at the Solar System’s innermost frontier.

The robotic science mission, with a price tag of nearly $2 billion, is led by the European Space Agency with contributions from Japan and the United States. Since its launch in 2018, BepiColombo has spiraled closer to the Sun using a combination of plasma propulsion and a series of flybys of Earth, Venus, and Mercury. The maneuvers changed the spacecraft’s velocity and steered it toward a final encounter with Mercury later this year.