The BepiColombo mission, a joint project between the European Space Agency and the Japan Aerospace Exploration Agency, has begun separating its science equipment from its transport module after launching in October 2018, according to the European Space Agency. The maneuver marks a critical phase in reaching Mercury, the least-explored planet in the inner solar system, with two instrument-heavy probes scheduled to begin gathering coordinated scientific data by April 2027.
BepiColombo Separates Transfer Module on Long Journey to Mercury
The Mercury Transfer Module separated from the spacecraft’s stack of two science orbiters, according to mission updates shared by the European Space Agency. Launched on an Ariane 5 rocket from Europe’s Spaceport near Kourou, French Guiana, the spacecraft has traveled more than 6 billion miles, according to mission data. Frank Budnik, flight dynamics manager for the mission at the European Space Agency, noted that reaching Mercury requires matching the planet’s exact velocity, making a direct path impossible without heavy energy investments.
To overcome this, the spacecraft relied on a combination of electric propulsion and nine gravitational flybys of Earth, Venus, and Mercury. Ignacio Tanco, head of Inner Solar System Mission Operations at the European Space Agency, compared the separation milestone to launching a completely new spacecraft around a distant world. Following the separation, the Mercury Transfer Module will remain in an orbit around the sun rather than impacting the planet, according to the mission’s flight dynamics team.
Two Independent Orbiters Target December Arrival
Gravity capture by Mercury will pull both the European Space Agency’s Mercury Planetary Orbiter and the Japan Aerospace Exploration Agency’s Mercury Magnetospheric Orbiter into orbit on November 21, according to mission schedules. The two spacecraft will then separate from each other between December 9 and 10. Santa Martinez, BepiColombo mission manager at the European Space Agency, explained that the Mercury Planetary Orbiter will focus on the planet itself, while the Mercury Magnetospheric Orbiter, or Mio, will examine the surrounding space environment, magnetosphere, and wispy atmosphere.
This configuration marks the first time a space mission has released two fully independent, fully operational separate spacecraft around another planet, according to Tanco. While some instruments gathered limited data during earlier flybys, the bulk of the science instruments remained inactive during the cruise phase due to spacecraft configuration. Full science operations will officially commence in April following orbital insertion maneuvers for both orbiters.
Solving Mysteries Left by Mariner 10 and MESSENGER
Mercury remains the least-explored planet in the inner solar system, having been visited by only two prior missions. NASA’s Mariner 10 completed three flybys in 1974 and 1975, followed decades later by NASA’s MESSENGER spacecraft, which arrived in 2011 and spent four years in orbit. Sean Solomon, a planetary scientist at Columbia University and principal investigator for MESSENGER, stated that while those missions mapped the surface and discovered unexpected volatiles and offset magnetic fields, fundamental questions about the planet’s formation remain unanswered.
Rachel Klima, a planetary geologist at the Johns Hopkins University Applied Physics Laboratory, noted that the upcoming observations will provide critical clarity on the planet’s mineral composition. Unlike MESSENGER, which relied on iron-rich rocks for mapping, the Mercury Planetary Orbiter carries advanced technology capable of reading surface minerals regardless of iron content. This capability is expected to shed light on how Mercury and the broader solar system formed.
Did you know?
Mercury is located about 36 million miles from the sun on average and completes one full orbit every 88 days, driving surface temperatures up to 800 degrees Fahrenheit during the day, according to NASA data.
Frequently Asked Questions
When will BepiColombo begin official science operations at Mercury?
Science operations are scheduled to officially begin in April, following the capture of both orbiters by Mercury’s gravity in November and their subsequent separation in December.
Which space agencies are responsible for the BepiColombo mission?
BepiColombo is a joint project of the European Space Agency and the Japan Aerospace Exploration Agency.
How many spacecraft make up the BepiColombo mission at Mercury?
The mission consists of two independent science orbiters: the European Mercury Planetary Orbiter and the Japanese Mercury Magnetospheric Orbiter.
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