Solar system generic
A transit of Mercury across the Sun takes place when the planet Mercury passes directly (transits) between the Sun and a superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Mercury appears as a tiny black dot moving across the disk of the Sun. Image Credit: Pixabay

Dubai: While much has been reported of recent explorations to Mars and the Moon, a joint European-Japanese mission has just completed a crucial manoeuvre on its journey to Mercury – swinging past Earth.

The spacecraft, BepiColombo, on a mission launched in October 2018, is trying to achieve an orbit around the innermost planet, a task which will require a seven-year trajectory, reported. The spacecraft came 12,963km away from Earth on Friday, approaching at an angle designed to slightly reduce its speed with respect to the sun. That adjustment will allow BepiColombo to head deeper into the solar system, the website said.

The mission needs to make sure it isn't travelling too fast when it arrives at Mercury in 2025 or it won't be able to go into orbit around the diminutive world, BBC reported.

"It would be so nice if we could take an express transfer and then we'd be there in a few months, but that doesn't work for this mission," Elsa Montagnon, the flight controller in charge of BepiColombo at the European Space Agency (Esa), told BBC News.

Apart from this flyby of Earth, the spacecraft needs to execute eight other manoeuvres – two at Venus and six at Mercury between 2021 and 2025 before the planet’s gravity traps the probe in December 2025.

What will BepiColombo do on Mercury?

Once BepiColombo arrives on Mercury, it will split into two constituent spacecraft. The first probe will orbit relatively high above Mercury's surface and focus on studying the magnetosphere, the region of space governed by the planet’s magnetic field

The second BepiColombo probe will approach closer to Mercury's surface and will focus on analysing the planet's composition. Scientists hope this work will help them understand how Mercury - and, in turn, the entire solar system - formed.

It is hoped the parallel observations can finally resolve the many puzzles about the hot little world. One of the key ones concerns the object's oversized iron core, which represents 60 per cent of Mercury's mass. Science cannot yet explain why the planet only has a thin layer of rocks, BBC reported.

Have there been other attempts to study Mercury?

This is only the third mission to study Mercury up close, a difficult task given its proximity to the sun. Nasa’s Mariner10 spacecraft flew past the tiny world three times in the 1970s, while Nasa’s Messenger spacecraft orbited Mercury from 2011 to 2015.

How much will it cost?

The mission which was launched in October 2018 costs around 3 billion euros (Dh11.9 billion).