Joint Mission to Mercury makes a ‘goodbye flyby’ of Earth

The joint European Space Agency (ESA) and Japanese Space Agency (JAXA) BepiColombo mission to Mercury was launched in 2018 and is currently in orbit around the sun at a similar distance to Earth. But it needs to change its course to reach another planet, so to help it along its journey it will get a gravity assist from Earth as it passes by the planet this week.

It will approach to within less than 8,000 miles of Earth, and as the craft swings by the planet, its gravitational pull can be used to adjust the craft’s trajectory and send it on its way toward the center of the solar system.

Artist’s impression of the BepiColombo spacecraft in cruise configuration, flying past Earth and with the Sun in the background.
Artist’s impression of the BepiColombo spacecraft in cruise configuration, flying past Earth and with the Sun in the background. ESA/ATG medialab

The flyby is visible with a small telescope

The flyby is scheduled for 9:25 p.m. PT on Thursday, April 9. BepiColombo will even come close enough that amateur astronomers should be able to spot it if they live in certain locations.

“BepiColombo should be visible with a small telescope, accessible to amateur astronomers in the southern hemisphere or in southern parts of the northern hemisphere,” Joe Zender, ESA BepiColombo Deputy Project Scientist, said in a statement. “If you live in southern Europe — south of Rome or Madrid, for example — you might be able to glimpse it for a moment, and the further south you are, the longer you should be able to see it. If something appears as a moving star in the field of view of your telescope or camera, that will be Bepi.”

About the BepiColombo craft

The BepiColumbo mission consists of three parts: Two spacecraft and one transfer module. The Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO) will both go into orbit around the planet Mercury to collect information from orbit, while the Mercury Transfer Module (MTM) will provide propulsion for the craft on its journey to Mercury. Together, the three parts are known as the Mercury Composite Spacecraft (MCS), and will perform the flyby of Earth as one.

BepiColombo cartoon characters 'hug' Earth ahead of the spacecraft's flyby, scheduled on 10 April.
BepiColombo cartoon characters ‘hug’ Earth ahead of the spacecraft’s flyby, scheduled on 10 April. On the left is the Mercury Planetary Orbiter (MTO), in the middle is the Mercury Magnetospheric Orbiter (MMO), and on the right is the Mercury Transfer Module (MTM). ESA

This will be the only flyby of Earth that BepiColombo performs on its journey, so it will soon head off and out of sight, which is leaving the mission team with mixed emotions. “The flyby has an emotional effect,” said Johannes Benkhoff, BepiColombo Project Scientist at ESA. “It’s the last time that we can see the spacecraft from Earth, so we are inviting amateur and professional astronomers to observe it before it goes.”

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