BepiColombo has been on a lengthy journey since its launch. The space probe, named after Italian scientist Giuseppe Colombo, who developed the gravity assist method for interplanetary travel, was originally set to arrive at Mercury in 2025. However, a propulsion malfunction required a change in course, delaying the arrival by nearly a year. After eight years in space, BepiColombo is now beginning its descent to low orbit around Mercury.
On September 3, ground control confirmed the successful separation of the propulsion module from the main craft, marking the final phase of the joint mission between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). The probe has traveled over 200 million kilometers from Earth, with transmissions indicating a smooth operation.
Mercury has been explored only twice before, both by NASA probes. Its proximity to the sun makes it particularly challenging to reach, as spacecraft must manage gravitational forces effectively to avoid falling into the sun. BepiColombo has utilized nine gravity assist maneuvers, swinging around Earth once, Venus twice, and Mercury six times, to control its speed.
Mercury's surface experiences extreme temperatures, exceeding 800 degrees Fahrenheit (430 degrees Celsius) during the day and dropping to -290 degrees Fahrenheit (-180 degrees Celsius) at night due to its lack of atmosphere. BepiColombo must withstand these temperature fluctuations.
Upon reaching its destination, BepiColombo will separate into two spacecraft: the Mercury Planetary Orbiter (MPO), which will analyze Mercury's surface and internal structure, and the Mercury Magnetospheric Orbiter (Mio), which will study the planet's magnetic field and atmosphere. This mission marks the first instance of multiple probes orbiting Mercury simultaneously, aiming to provide a more detailed understanding than a single probe could achieve.
Following the spacecraft's preparation for scientific observations, full-scale observations are set to commence in April 2027. Mio will enter a higher elliptical orbit, while MPO will lower its altitude to reach its final orbit by March 2027. Prior to scientific observations, several procedures, including the deployment of Mio's sunshield, must be completed.
The mission aims to address several key questions about Mercury, including the reasons behind its large iron core, the presence of ice in shadowed craters, its unique magnetic field, and the nature of surface depressions known as 'hollows.' The findings are expected to provide insights into the formation and evolution of terrestrial planets, including Earth. Additionally, precise orbital data from the mission will be used to test Einstein's general theory of relativity, as Mercury's proximity to the sun makes it an ideal location for studying gravitational effects on spacetime.