BepiColombo First Venus FlyBy
The primary role of a flyby is to help the spacecraft saving fuel to reach its final target with a lighter launch configuration. In the case of BepiColombo, indeed, 9 flybys in total are planned before the spacecraft will reach its final orbit around Mercury. Two of the flybys will be performed at Venus, and are needed to decrease BepiColombo velocity (and, as a consequence, also the semi-major axis of the orbit) with respect to the Sun, and move closer to Mercury.
Planetary flybys are also a great occasion to test and calibrate the on-board instrumentation in well-known environments (this happened, for example, last April 10th 2020 during the Earth flyby).
Even more, planetary flybys are special orbiatal configurations to get valuable scientific observations of the environment of a planet and of some of its peculiar features.
This is exactly what will happen with Venus: given the BepiColombo instrumentation that may operate during cruise, and considering that it is specifically designed for a totally different environment like Mercury is, there are nevertheless two possible topics of investigation at Venus:
- Atmosphere - Venus thick atmosphere, with its super-rotating clouds, and complex chemistry (now including also phosphine, recently believed to be a potential trace of some form of life…)
- Ionosphere / Induced magnetosphere – having no intrinsic magnetic field to shield it, Venus atmosphere interacts directly with the solar wind, interplanetary magnetic field and radiation, creating a complex population of ionized particles and induced magnetic fields.
The trajectory of the first flyby is shown below. The spacecraft will approach Venus from the dayside at a velocity (with respect to Venus) of 8.3 km/s, and reach the minimum distance of 10720 km from its surface when being on the evening flank, on 15th October 2020 at 03:58 UTC.
At about this time it will also enter the bow shock, cross the magnetosheath and the ionospheric boundaries and enter into the magnetotail, where it will probably remain for the following days before exiting again in the solar wind (exact extent of the magnetic envelope depending on the in-situ conditions of solar wind and dynamic pressure, not known in advance).
The instruments that will operate are:
- Onboard MPO: ISA, MERTIS, MGNS, MORE, MPO-MAG, PHEBUS, SERENA (PICAM and MIPA sensors), SIXS, BERM
- Onboard MMO: MPPE, MGF, PWI
- Onboard MTM: MCAM 2 and 3, BERM
For further information, please, visit the ESA's Cosmos Venus Flyby page