The BepiColombo spacecraft, operated by the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA), could feel the heat even before it reaches its destination: Mercury. Thanks to a malfunction, the spacecraft’s thrusters are no longer operating at full power. The team has yet to determine how this will affect upcoming maneuvers, such as a Mercury flyby scheduled for later this year.
BepiColombo is destined to become only the second mission to orbit Mercury, in December 2025. It consists of two probes and something called the ‘Mercury Transfer Module’, which scientists hope will answer many confusing questions about the smallest planet in our solar system will answer. (To be clear, BepiColombo has performed Mercury flybys before, but has yet to actually enter Mercury’s orbit.)
These questions include things like how Mercury can be so blisteringly hot and still have ice in its polar craters, why the planet has a weak magnetic field, and what the mysterious cavities on its surface are.
The 77 million kilometer journey to Mercury is far from easy for BepiColombo; The spacecraft will make a total of nine planetary flybys before being placed into the relatively small planet’s orbit. And as ESA reports, the malfunction the spacecraft experienced on April 26 has made this journey even more complicated.
Related: Venus leaks carbon and oxygen, according to a cursory visit by BepiColombo
BepiColombo, launched on October 20, 2018 from ESA’s launch site in Kourou, French Guiana, atop an Ariane 5 rocket, encountered the problem as it prepared to perform an in-space maneuver that would help prepare it for its fourth flight past Mercury on September 5, 2024.
The Mercury Transfer Module is equipped with solar panels and an electric propulsion system used to generate thrust. As the spacecraft was about to begin its April 26 maneuver, operators discovered that the transfer module had failed to provide sufficient electrical power to the thrusters.
Once the fault was identified, ESA operators got to work fixing it. By May 7, the team had restored power to the thrusters so that they reached 90% of full capacity, but the available power from the Mercury Transfer Module is still lower than it should be. This means that BepiColombo continues to operate at full capacity.
ESA said the BepiColombo team’s main priorities at the moment are to keep the spacecraft’s thrust stable at its current suboptimal level, and to find out how the spacecraft will handle upcoming maneuvers with less than full propulsion. Operators are also trying to determine what caused the power drop and to assess whether full power can indeed be restored.
During its journey to Mercury, BepiColombo completed one flyby of Earth on April 10, 2020, and two flybys of Venus on October 15, 2020 and August 10, 2021. During these later flybys, the spacecraft collected important scientific data about Venus, which is the second planet from the sun and the hottest world in the solar system.
BepiColombo made its first flyby of Mercury on October 1, 2021, followed by the second and third flybys on June 23, 2022 and June 19, 2023. As mentioned above, the fourth flyby is scheduled for September 5 this year. with a fifth and sixth flyby of the first planet from sunset on December 2, 2024 and January 9, 2025.
ESA has yet to reveal if and how the thrust failure will affect these operations or the overall timeline of the mission, which will end on May 1, 2028, after BepiColumbo will have spent 10 Mercury years in orbit around the small planet.