The European Space Agency (ESA) announced during the night last night (April 10, 2020) that the BepiColombo spacecraft had successfully completed the first of nine planetary flybys – in this case of our own planet, Earth – coming less than 8,000 miles (12,700 km) from Earth’s surface at 04:25 UTC (12:25 a.m. EDT). Translate UTC to your time. The tug of Earth’s gravity finely altered the spacecraft’s speed and direction, steering it subtly toward its final destination, Mercury. ESA said:
Images gathered just before closest approach portray our planet shining through darkness, during one of humankind’s most challenging times in recent history.
ESA said the flybys:
… together with the onboard solar propulsion system, will help the spacecraft reach its target orbit around Mercury. The next two flybys will take place at Venus and a further six at Mercury itself.
ESA said the flyby didn’t require any active operations from the BepiColombo ground team, such as firing thrusters. But it did include 34 critical minutes shortly after BepiColombo’s closest approach to our planet, when the spacecraft flew through Earth’s shadow. Elsa Montagnon, BepiColombo Spacecraft Operations Manager for ESA, explained why the team needed to be on hand at ESA’s mission control center in Darmstadt, Germany, for this maneuver:
This eclipse phase was the most delicate part of the flyby, with the spacecraft passing through the shadow of our planet and not receiving any direct sunlight for the first time after launch.
It is always nerve-wracking to know a spacecraft’s solar panels are not bathed in sunlight. When we saw the solar cells had restarted to generate electrical current, we knew BepiColombo was finally out of Earth’s shadow and ready to proceed on its interplanetary journey.
As BepiColombo swung by our planet, most scientific instruments on ESA’s Mercury Planetary Orbiter – one of the two science spacecraft that make up the mission – were switched on. Several sensors were also active on the second component of the mission, including JAXA’s Mercury Magnetospheric Orbiter, also known as Mio.
Launched in 2018, BepiColombo is on a seven-year journey to Mercury, the smallest and innermost planet orbiting the sun. Read more: Top 5 Mercury mysteries that BepiColombo will solve.
Bottom line: The BepiColombo spacecraft – en route to Mercury – successfully used Earth’s gravity last night to fine-tune its journey to the innermost part of the solar system. During the close flyby, BepiColombo captured images of Earth.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.