The ESA-JAXA mission BepiColombo has completed the first of two flybys of Venus needed to put it on course for the innermost planet of the solar system, Mercury. The closest approach to the Earth’s hot sister took place this morning (15. 10.) at 03:58 GMT at a distance of about 10 720 km from the planet’s surface.

Launched on 20 October 2018, the spacecraft will require nine gravity assist fly-bys – one to Earth, two to Venus and six to Mercury – before it can enter orbit around Mercury in 2025. The flybys will use the gravitational pull of the planets to change the spacecraft’s speed and direction, and together with the spacecraft’s solar-electric propulsion system, will help BepiColombo reduce its speed to a level that will allow it to reach Mercury’s orbit.

The probe has also photographed Venus as it passes by. However, little new information is expected from this. «The flyby itself was very successful,» says Elsa Montagnon, ESA operations manager for the BepiColombo spacecraft. «The only difference to normal operation during the cruise phase is that, near Venus, we have to temporarily close the aperture of one of the launchers. You could be blinded by the planet, just like closing your eyes to avoid looking at the sun».

Two of the three surveillance cameras on board the Mercury Transfer Module were activated during the 20 hours prior to the approach up to 15 minutes later. From a distance, Venus can be seen as a small disk in the field of view of the camera, which is located near the spacecraft body. During the close approach phase the planet dominates the view, it «rises» behind the magnetometer boom of the Mercury planetary orbiter.

Seven of the eleven scientific instruments on board the European Mercury planetary orbiter and its radiation monitor, as well as three of five on board the Japanese Mercury magnetosphere orbiter were active during the flyby. While the sensors are designed to study Mercury’s rocky, atmosphere-free environment, the flyby provided a unique opportunity to collect scientific data on Venus.

«After the successful flyby of Earth, during which our instruments worked even better than expected, we are excited to see what will come out of the flyby of Venus», says Johannes Benkhoff, ESA scientist on the BepiColombo project.

«We have to be patient while our Venus specialists carefully examine the data, but we hope to be able to provide some temperature and density profiles of the atmosphere, information about the chemical composition and cloud cover, and the interaction of the magnetic environment between the Sun and Venus. But we expect more results in the coming year, given the closer flyby distance». During the 2021 flyby, which is scheduled for August 10, the spacecraft will pass the planet’s surface at a distance of only 550 km.