BepiColombo Begins Tricky Arrival Phase at Mercury After 8-Year Journey

The BepiColombo spacecraft began its months-long, high-risk approach to Mercury on Thursday, marking a critical transition in the joint European and Japanese mission to study the Solar System’s smallest and least understood rocky planet, according to reporting by CNN and Yahoo.

Launched in 2018, the mission arrived roughly 63 million kilometers from the Sun and 200 million kilometers from Earth on Thursday, as reported by Yahoo. Because of the vast distance, commands from ground control encounter an approximate 30-minute delay, forcing the spacecraft to execute its initial maneuvers autonomously.

The European Space Agency (ESA) described the arrival phase as its most operationally challenging planetary arrival sequences ever attempted, according to Yahoo. Mercury possesses a relatively tiny mass, making it only slightly bigger than the Moon. That weak gravitational pull compared to the Sun complicates orbital insertion, as spacecraft risk being incinerated or lost in space without careful trajectory management.

Spacecraft Reconfiguration and Probe Separation

To reach its destination, the spacecraft traveled more than 10 billion kilometers and completed nine flybys to adjust its speed and trajectory, according to Yahoo. On Thursday, the transfer module propelled the two attached science probes away from the main propulsion unit in what ESA head of inner solar system mission operations Ignacio Tanco compared to launching a new spacecraft around a different planet, as reported by Yahoo.

The spacecraft autonomously cut four mechanical struts connecting the orbiters to the module, allowing spring mechanisms to push the probes away at a speed of 40 centimeters per second. Mission controllers in Darmstadt, Germany, received telemetry confirming the successful separation at 1353 GMT on Thursday.

The spacecraft has completed its reconfiguration as expected,

— Elsa Montagnon, in charge of module operations at ESA

Upcoming Orbital Insertion Milestones

Following the successful separation phase, the probes are scheduled to enter Mercury’s orbit on November 21, according to Yahoo. A subsequent operational phase will take place on December 9 and 10, when the two probes separate from each other to enter their respective individual orbits.

Science operations are slated to begin in April. The ESA Mercury Planetary Orbiter (MPO) will study the planet with unprecedented precision, passing as close as 480 kilometers from the surface, according to Yahoo. Meanwhile, the Japanese Mercury Magnetospheric Orbiter (Mio) will use an elliptical orbit reaching up to 11,000 kilometers away to analyze the planet’s space environment and magnetic field.

Mercury remains the least studied of the four rocky, innermost planets in the solar system, following prior visits by NASA’s Mariner 10 in 1974 and the MESSENGER orbiter in 2011, according to Yahoo. Supported by 16 scientific instruments and a 1.7-billion-euro budget, the BepiColombo mission aims to clarify lingering mysteries surrounding the planet’s iron core, magnetic field, and hollow-marked surface.