Information in a nutshell


15 October 2020

10 August 2021 (*)

Closest approach

03:58 UTC

13:57 UTC (*)

Minimum Altitude

10720 km

552 km

Operation time

about 2 days before and 2 after Closest Approach

about 2 days before and 2 after Closest Approach

Payloads Operated






MTM: MCAM1/2/3

(*) minor changes in time of closest approach and trajectory may still occur for flyby #2. Consolidation after the next Solar Electric Propulsion Arc.


The images below show the flyby trajectories of BepiColombo at Venus on October 15th 2020 (Bepi I,red) and August 10th 2021 (Bepi II, blue). Figure 1 shows the projection onto the VSO X-Y plane (-Y up); Figure 2 shows the projection onto the X-Z plane. Numbers plotted along the orbits give the expected universal time. Green and cyan profiles show average positions of bow shock and ion composition boundary respectively (as modeled after Martinecz et al., 2009).

Figure1: Venus flybys trajectories in XY plan, VSO system (courtesy of Markus Fraenz, MPI, Goettingen, Germany). Note that Y axes in increasing downwards. Units are in Venusian Radii.

Figure 2: Venus flybys trajectories in XZ plan, VSO system (courtesy of Markus Fraenz, MPI, Goettingen, Germany). Units are in Venusian Radii.

Simulated ion mass fluxes are also mapped in the background as derived by using the code PLUTO (Mignone et al., 2007, 2012 ) for average solar wind conditions (orange circle, corresponding to a value of mass flux of about 5 10^8 p/cm^2 s), and ionospheric parameters as in the colorbar to the right.

BepiColombo Venus first flyby

After the instruments tests performed during the Earth flyby on April 10th 2020, the first Venus flyby will be the first occasion to use instruments for scientific purposes in a planetary environment.

The flyby at Venus will be on October 15th, 2020, almost 2 years after launch, at 03:58:31 UTC (Closest Approach, CA).

As Figure 1 shows, BepiColombo will approach the planet from the dayside and – given the retrograde rotation of Venus - it will have the closest approach on the evening side, almost at the time of crossing the bowshock.

Minimum distance from the center of the planet will be 16771.5 km (that is an altitude of 10720.5 km above the planet surface). Distance from the Earth will be 1.16 AU and from the Sun 0.71 AU.

Apparent angular size of the planet at closest approach will be about 42°.

Hence, the flyby will occur at an altitude of about 2 Venus radii, and the spacecraft is expected to cross the bowshock near the CA time; the ionopause, instead, will be crossed later, when already in the tail region for the first time, at < 10 RV (entrance), and a second time much later (exit). Exit from the bowshock is expected to occur even later.

The flyby#1 configuration is optimal for both atmospheric and ionospheric/magnetospheric investigations of the Venus close environment.

Instruments on board will operate in the days around the Venus closest approach (15th October 2020) according to the following timeline:


As it can be noted in the timeline, and for what concerns the planetary investigations of Venus, some instruments are acquiring data only in the hours around the flyby (the magnetometer and other sensors onboard MMO, PHEBUS, SERENA/MIPA and /PICAM, MERTIS, SIXS) while others like MAG, ISA, MGNS, BERM and MORE are operating almost continuously during the cruise.

The potential scientific outputs of these observations are discussed below in the Scientific Investigation [add link to section below].

BepiColombo Venus second flyby

The second flyby at Venus will be about 10 months later, on August 10th, 2021 (the detailed time still subject to minor changes). The much lower altitude above the surface (552 km) will allow a different range of investigations that will be addressed in detail in the next future. Another feature that mainly differs the second flyby from the first is that Venus will be approached from the nightside, even if still approaching the planet from the evening terminator.

Detailed analysis will be uploaded in the next months, after orbit consolidation.

Venus flybys scientific investigations

Given the BepiColombo instrumentation that may operate during cruise (see table on top of the page), and considering attitude and field of view limitations due to the stack configuration of Bepi during the cruise, the possible topics of investigation at Venus are the following:

  • Atmosphere: In the 2020 and 2021 close encounter periods, and in selected periods where BepiColombo is between 0.3 and 0.8 AU from Venus, Venus’s atmosphere will be observed by MERTIS (the 7-14 µm infrared spectrometer and 7-40 µm radiometer) and PHEBUS (the 4-channel UV spectrometer). In October 2020 MERTIS will observe Venus’ dayside near-continuously over the 55-hour period leading up to closest approach. MERTIS will sense Venus’ middle atmosphere and cloud layers, providing temperature profiles and detecting CO2, SO2, H2SO4 cloud aerosol properties. MERTIS observations will contribute to studies of Venus’ radiative balance, atmospheric structure, cloud level chemical processes, and the impact of global-scale atmospheric waves on Venus’ weather patterns. At closest approach on 15 October, 2020 the PHEBUS spectrometer will be used to complete nightside atmosphere stellar occultations in the FUV channel (145-315 nm) providing density profiles of bulk and trace gas species, and detecting NO emission on Venus’ nightside. These data will be used to study the atmospheric structure between 80 and 200 km altitude, and the zonal transport processes in the thermosphere (at about 110 km). The MGNS neutron and gamma spectrometers will also contribute to the investigation of Venus’ atmospheric chemistry and dynamics by detecting elemental composition in terms of C, O, N and H2O. The Bepi enabled Venus Atmosphere investigations will be further supported by complementary observations completed by the Akatsuki spacecraft presently orbiting around Venus, and other Earth-based telescopes, expanding the scope of study to Venus' climate.
    To learn more click here


  • Ionosphere – Induced magnetosphere: Venus has no intrinsic dipole magnetic field and thus the solar wind plasma can easily approach the planet and interact directly with the upper atmosphere, leading to the formation of an ionosphere, ion plasma boundaries and induced magnetosphere.
    During the BepiColombo passage, the investigation of the extended region from the outer unperturbed solar wind, through the bowshock, the magnetosheath, ionosphere and magnetotail, can be performed by several instruments onboard. First of all, the two magnetometers (MAG and MGF) may provide magnetic field measurements along the whole period. Then, a wide set of ion, electron and plasma sensors at different energy ranges of the particles suites: SERENA, PWI, MPPE. Their joint measurements will be fundamental to detect the position of the different plasma boundaries and composition of the different layers of the complex ionized environment. Moreover, detection of draped dayside magnetic fields, low frequency wave activity in the ion composition boundary, flux ropes and tail lobes polarity are all interesting potential measurements. In addition, measurements of energetic neutral atoms as derived from solar wind ion sputtering over the exobase, electron shielding effects and detection of atmospheric pick-up ions could help to relate the ionized and neutral components of the Venus environment, hence the induced magnetosphere with the atmosphere themselves.
    To learn more click here

Venus flybys WORKING GROUP

The Venus Flybys Working group (VFBWG) aims to promote discussion on Venus science as related to the BepiColombo passages nearby the planet, and focus on the synergy of the different instrumentation onboard and its possible contribution to Venus science.

In addition, coordination among the BepiColombo instrumentation and other spacecraft at Venus (i.e. Akatsuki from JAXA) and Earth-based observation campaign is the other focus of the working group.

Venus flybys working group splinters are organized now monthly, usually the same day of the BepiColombo SWT meetings (now virtual), right after it, or a day after. The participation to the working group splinters is open to all BepiColombo team members and welcome to all Venus experts.


Any scientist interested to the Venus science to be performed by BepiColombo may contact us:

  • WG Chair: Valeria Mangano, INAF-IAPS Roma, Italy (email: name.surname at
  • Guest scientist: Kandis Lea Jessup, SWRI Boulder, CO, USA
  • Guest scientist: Yeon Joo Lee, Technische Universität Berlin, Germany




WG Chair: Valeria Mangano, INAF-IAPS Roma, Italy email


Guest scientist: Kandis Lea Jessup, SWRI Boulder, CO, USA email


Guest scientist: Yeon Joo Lee, Technische Universität Berlin, Germany email