Paris (AFP)

The BepiColombo satellite dedicated to the exploration of Mercury flew over Earth on Friday and took advantage of its gravity to redirect its trajectory and continue its long journey to the planet closest to the Sun, announced the European Space Agency (ESA).

The probes of the European (ESA) and Japanese (JAXA) space agencies on board the satellite passed 12,700 kilometers from the surface of the Earth at 4:25 GMT, above the Southern hemisphere, to be redirected to their final destination, after a gravitational assistance maneuver.

Launched in October 2018, the BepiColombo mission has been in orbit around the Sun for a year, at a distance similar to that of Earth. It must be placed in orbit around Mercury in 2025 only, at the end of a complex trajectory, because the smallest of the planets in the solar system is very difficult to reach.

If the satellite had been launched directly towards Mercury, it would have arrived at "a speed such that it would have been necessary to carry out a gigantic braking maneuver to succeed in placing it in orbit, so much the attraction of the Sun is strong", explained to AFP Elsa Montagnon, who steers operations from the ESA control center in Darmstadt, Germany.

This braking would have supposed to embark too much fuel for a spacecraft of this size. Hence the choice to take a roundabout path, and to use the natural gravity of the Earth, then of Venus, which will allow it to slow down "naturally" during its journey.

During the gravitational assistance maneuver on Friday - the first since its launch - the spacecraft was attracted to the Earth, whose gravity made it "lose energy", which allowed it to brake, detailed the operations manager, adding that the overflight of the Earth had "gone well".

For around thirty minutes, BepiColombo then went into an eclipse phase, in the shadow of the Earth, a delicate period to manage, but one that went well, detailed Elsa Montagnon.

"It's always very stressful to know that the solar panels of a spacecraft are not flooded with sun. When we saw that the solar cells restarted to generate electric current, we knew that BepiColombo had finally come out of the shadow of the Earth and ready to continue its interplanetary journey, "she added.

The satellite is now heading towards Venus, which it will fly over twice this year, before propelling itself towards its final destination.

Its scientific instruments must study the composition of Mercury in order to solve the mystery of the formation of this burnt planet, the least explored of the four rocky planets of the solar system, and to understand the evolution of this entire system.

© 2020 AFP