The BepiColombo spacecraft, operated by the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA), can feel the heat even before it reaches its destination: Mercury. Thanks to a bug, the spacecraft’s thrusters are no longer operating at full power. The team has not yet determined how this will affect upcoming maneuvers, such as the Mercury flyby scheduled for later this year.
Destined to become only the second mission to orbit Mercury in December 2025, BepiColombo consists of two probes and something called a “Mercury Transfer Module” that scientists hope will answer many perplexing questions about the world’s smallest planet. our solar system. (To be clear, BepiColombo has made flybys of Mercury before, but has yet to enter Mercury’s orbit.)
These questions include things like how Mercury can be so hot yet still have ice in its polar craters, why the planet has a weak magnetic field, and what are the mysterious cavities observed on its surface.
The 48 million mile (77 million kilometer) journey to Mercury is far from easy for BepiColombo; the spacecraft will make a total of nine planetary flybys before being inserted into the relatively small planet’s orbit. And as ESA reports, the problem experienced by the spacecraft on April 26 complicated that journey further.
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BepiColombo, which launched on October 20, 2018 from ESA’s launch facility in Kourou, French Guiana, atop an Ariane 5 rocket, experienced a problem while preparing to perform an in-space maneuver that would help it prepare for its fourth flyby of Mercury on September 5, 2024.
The Mercury Transfer Module is equipped with solar arrays and an electric propulsion system used to generate thrust. As the spacecraft was about to begin its maneuver on April 26, however, operators discovered that the transfer module had failed to deliver enough electrical power to its thrusters.
As soon as the failure was identified, ESA operators set about fixing it. By May 7, the team had restored power to the thrusters so they reached 90% full capacity, but the power available from the Mercury Transfer Module was still below what it should be. This means that BepiColombo continues to operate without its full capacity.
ESA said the BepiColombo team’s main priorities right now are to keep the spacecraft’s thrust stable at its current suboptimal levels and to work out how the spacecraft will handle upcoming maneuvers at less than full propulsion. Operators are also working to determine what caused the power outage and determine whether full power can indeed be restored.
During its journey to Mercury, BepiColombo performed 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 for 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, with its second and third flybys following on June 23, 2022 and June 19, 2023. As mentioned above, the fourth flyby of Mercury is scheduled for September 5 this year, with the fifth and sixth flybys of the first planet from the sun set for December 2, 2024 and January 9, 2025.
ESA has not yet disclosed if and how the thruster failure will affect these operations or the overall timeline of the mission, which is due to end on May 1, 2028, after BepiColumbo will have spent 10 years on Mercury orbiting the small planet.
