A spacecraft launched nearly a decade ago is finally closing in on Mercury, the solar system's smallest and least explored planet. The BepiColombo mission, a joint effort between the European Space Agency and Japan's space agency JAXA, is on its final approach after a 9 billion kilometer trek that included multiple flybys of Earth, Venus, and Mercury itself. Mission controllers have called the upcoming orbital insertion a "brilliant moment" after years of patience and precision flying.
A decade of detours and gravity assists
BepiColombo left Earth in October 2018, but it has not taken a direct path to Mercury. The spacecraft has used nine planetary flybys to slow down and adjust its trajectory, because Mercury's proximity to the Sun makes it notoriously difficult to reach. The probe has already sent back striking images of the planet's cratered surface during those close passes, giving scientists their first fresh look at Mercury in decades.
The mission is named after Giuseppe Colombo, the Italian mathematician who first explained Mercury's rotational resonance with the Sun. BepiColombo is actually two orbiters in one: the Mercury Planetary Orbiter and the Mercury Magnetospheric Orbiter, both designed to study the planet from complementary angles once they separate in orbit.
What happens when it arrives
In December 2025, the spacecraft is scheduled to fire its thrusters to enter Mercury's orbit, a maneuver that will end its long cruise phase and begin the primary science mission. Once in orbit, the two probes will study Mercury's magnetic field, its thin exosphere, and the mysterious composition of its surface, which is rich in volatile elements that should not survive so close to the Sun.
For the scientists and engineers who have worked on BepiColombo for over two decades, the arrival is the payoff for years of waiting. The mission has already survived technical glitches, including a propulsion problem that forced controllers to improvise with alternative thruster settings. Despite those hurdles, the spacecraft remains on track for its historic rendezvous.
Why this matters to people on Earth
Mercury is a world of extremes, with daytime temperatures hot enough to melt lead and nighttime cold enough to freeze nitrogen. Understanding how such a planet formed and evolved can reveal clues about the early solar system, including how rocky planets like Earth came to be. For Japan, which has contributed key instruments and expertise to the mission, the arrival is a point of national pride in its growing deep-space portfolio.
The orbital insertion will be a tense moment, but the mission team has prepared for every scenario. If all goes well, BepiColombo will become only the second spacecraft ever to orbit Mercury, following NASA's Messenger probe, which ended its mission in 2015. The data it collects over its planned two-year mission could rewrite textbooks on planetary science.
As the spacecraft makes its final approach, the world will be watching a journey that began with a launch in French Guiana and will end with a delicate dance around a scorched, cratered world. The decade of waiting is almost over, and the payoff promises to be extraordinary.
